diff --git a/core/prelude/operators.carbon b/core/prelude/operators.carbon
index 4d156f2866e1..a24bb255a583 100644
--- a/core/prelude/operators.carbon
+++ b/core/prelude/operators.carbon
@@ -6,5 +6,6 @@ package Core library "prelude/operators";
 
 export import library "prelude/operators/arithmetic";
 export import library "prelude/operators/as";
+export import library "prelude/operators/index";
 export import library "prelude/operators/bitwise";
 export import library "prelude/operators/comparison";
diff --git a/core/prelude/operators/index.carbon b/core/prelude/operators/index.carbon
new file mode 100644
index 000000000000..9582c9313b0a
--- /dev/null
+++ b/core/prelude/operators/index.carbon
@@ -0,0 +1,9 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+package Core library "prelude/operators/index";
+
+interface IndexWith(SubscriptType:! type, ElementType:! type) {
+  fn At[self: Self](subscript: SubscriptType) -> ElementType;
+}
diff --git a/toolchain/check/BUILD b/toolchain/check/BUILD
index 7d217b2a8e27..caaea7ce223b 100644
--- a/toolchain/check/BUILD
+++ b/toolchain/check/BUILD
@@ -126,6 +126,7 @@ cc_library(
         "//toolchain/parse:node_kind",
         "//toolchain/parse:tree",
         "//toolchain/parse:tree_node_diagnostic_converter",
+        "//toolchain/sem_ir:builtin_inst_kind",
         "//toolchain/sem_ir:entry_point",
         "//toolchain/sem_ir:file",
         "//toolchain/sem_ir:ids",
diff --git a/toolchain/check/handle_index.cpp b/toolchain/check/handle_index.cpp
index ec94efb466af..ca38e137ab22 100644
--- a/toolchain/check/handle_index.cpp
+++ b/toolchain/check/handle_index.cpp
@@ -2,11 +2,17 @@
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 
+#include <optional>
+
 #include "toolchain/base/kind_switch.h"
 #include "toolchain/check/context.h"
 #include "toolchain/check/convert.h"
 #include "toolchain/check/handle.h"
+#include "toolchain/check/operator.h"
+#include "toolchain/diagnostics/diagnostic.h"
+#include "toolchain/sem_ir/builtin_inst_kind.h"
 #include "toolchain/sem_ir/inst.h"
+#include "toolchain/sem_ir/typed_insts.h"
 
 namespace Carbon::Check {
 
@@ -16,17 +22,113 @@ auto HandleParseNode(Context& /*context*/, Parse::IndexExprStartId /*node_id*/)
   return true;
 }
 
+// Returns the argument values of the `IndexWith` interface. Arguments
+// correspond to the `SubscriptType` and the `ElementType`. If no arguments are
+// used to define `IndexWith`, this returns an empty array reference. If the
+// class does not implement the said interface, this returns a `std::nullopt`.
+// TODO: Switch to using an associated type instead of a parameter for the
+// `ElementType`.
+static auto GetIndexWithArgs(Context& context, Parse::NodeId node_id,
+                             SemIR::TypeId self_id)
+    -> std::optional<llvm::ArrayRef<SemIR::InstId>> {
+  auto index_with_inst_id = context.LookupNameInCore(node_id, "IndexWith");
+  // If the `IndexWith` interface doesn't have generic arguments then return an
+  // empty reference.
+  if (context.insts().Is<SemIR::InterfaceType>(index_with_inst_id)) {
+    return llvm::ArrayRef<SemIR::InstId>();
+  }
+
+  auto index_with_inst =
+      context.insts().TryGetAsIfValid<SemIR::StructValue>(index_with_inst_id);
+  if (!index_with_inst) {
+    return std::nullopt;
+  }
+
+  auto index_with_interface =
+      context.types().TryGetAs<SemIR::GenericInterfaceType>(
+          index_with_inst->type_id);
+  if (!index_with_interface) {
+    return std::nullopt;
+  }
+
+  for (const auto& impl : context.impls().array_ref()) {
+    auto impl_self_type_id = context.GetTypeIdForTypeInst(impl.self_id);
+    auto impl_constraint_type_id =
+        context.GetTypeIdForTypeInst(impl.constraint_id);
+
+    if (impl_self_type_id != self_id) {
+      continue;
+    }
+    auto interface_type =
+        context.types().TryGetAs<SemIR::InterfaceType>(impl_constraint_type_id);
+    if (!interface_type) {
+      continue;
+    }
+
+    if (index_with_interface->interface_id != interface_type->interface_id) {
+      continue;
+    }
+
+    return context.inst_blocks().GetOrEmpty(
+        context.specifics().Get(interface_type->specific_id).args_id);
+  }
+
+  return std::nullopt;
+}
+
+// Performs an index with base expression `operand_inst_id` and
+// `operand_type_id` for types that are not an array. This checks if
+// the base expression implements the `IndexWith` interface; if so, uses the
+// `At` associative method, otherwise prints a diagnostic.
+static auto PerformIndexWith(Context& context, Parse::NodeId node_id,
+                             SemIR::InstId operand_inst_id,
+                             SemIR::TypeId operand_type_id,
+                             SemIR::InstId index_inst_id) -> SemIR::InstId {
+  auto args = GetIndexWithArgs(context, node_id, operand_type_id);
+
+  // If the type does not implement the `IndexWith` interface, then return
+  // an error.
+  if (!args) {
+    CARBON_DIAGNOSTIC(TypeNotIndexable, Error,
+                      "type {0} does not support indexing", SemIR::TypeId);
+    context.emitter().Emit(node_id, TypeNotIndexable, operand_type_id);
+    return SemIR::InstId::BuiltinError;
+  }
+
+  Operator op{
+      .interface_name = "IndexWith",
+      .interface_args_ref = *args,
+      .op_name = "At",
+  };
+
+  // IndexWith is defined without generic arguments.
+  if (args->empty()) {
+    return BuildBinaryOperator(context, node_id, op, operand_inst_id,
+                               index_inst_id);
+  }
+
+  // The first argument of the `IndexWith` interface corresponds to the
+  // `SubscriptType`, so first cast `index_inst_id` to that type.
+  auto subscript_type_id = context.GetTypeIdForTypeInst((*args)[0]);
+  auto cast_index_id =
+      ConvertToValueOfType(context, node_id, index_inst_id, subscript_type_id);
+
+  return BuildBinaryOperator(context, node_id, op, operand_inst_id,
+                             cast_index_id);
+}
+
 auto HandleParseNode(Context& context, Parse::IndexExprId node_id) -> bool {
   auto index_inst_id = context.node_stack().PopExpr();
   auto operand_inst_id = context.node_stack().PopExpr();
   operand_inst_id = ConvertToValueOrRefExpr(context, operand_inst_id);
   auto operand_inst = context.insts().Get(operand_inst_id);
   auto operand_type_id = operand_inst.type_id();
+
   CARBON_KIND_SWITCH(context.types().GetAsInst(operand_type_id)) {
     case CARBON_KIND(SemIR::ArrayType array_type): {
-      auto index_node_id = context.insts().GetLocId(index_inst_id);
+      auto index_loc_id = context.insts().GetLocId(index_inst_id);
       auto cast_index_id = ConvertToValueOfType(
-          context, index_node_id, index_inst_id,
+          context, index_loc_id, index_inst_id,
           context.GetBuiltinType(SemIR::BuiltinInstKind::IntType));
       auto array_cat =
           SemIR::GetExprCategory(context.sem_ir(), operand_inst_id);
@@ -52,13 +154,14 @@ auto HandleParseNode(Context& context, Parse::IndexExprId node_id) -> bool {
       context.node_stack().Push(node_id, elem_id);
       return true;
     }
+
     default: {
+      auto elem_id = SemIR::InstId::BuiltinError;
       if (operand_type_id != SemIR::TypeId::Error) {
-        CARBON_DIAGNOSTIC(TypeNotIndexable, Error,
-                          "type {0} does not support indexing", TypeOfInstId);
-        context.emitter().Emit(node_id, TypeNotIndexable, operand_inst_id);
+        elem_id = PerformIndexWith(context, node_id, operand_inst_id,
+                                   operand_type_id, index_inst_id);
       }
-      context.node_stack().Push(node_id, SemIR::InstId::BuiltinError);
+      context.node_stack().Push(node_id, elem_id);
       return true;
     }
   }
diff --git a/toolchain/check/testdata/alias/fail_bool_value.carbon b/toolchain/check/testdata/alias/fail_bool_value.carbon
index e4c2f1140ee0..c27e7bc6615b 100644
--- a/toolchain/check/testdata/alias/fail_bool_value.carbon
+++ b/toolchain/check/testdata/alias/fail_bool_value.carbon
@@ -31,6 +31,7 @@ let a_test: bool = a;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/alias/fail_builtins.carbon b/toolchain/check/testdata/alias/fail_builtins.carbon
index b9866e56b4a6..55c3dc0c84b8 100644
--- a/toolchain/check/testdata/alias/fail_builtins.carbon
+++ b/toolchain/check/testdata/alias/fail_builtins.carbon
@@ -38,6 +38,7 @@ alias b = bool;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/alias/fail_control_flow.carbon b/toolchain/check/testdata/alias/fail_control_flow.carbon
index a8fab92e5672..1f744167ab8c 100644
--- a/toolchain/check/testdata/alias/fail_control_flow.carbon
+++ b/toolchain/check/testdata/alias/fail_control_flow.carbon
@@ -35,6 +35,7 @@ alias a = true or false;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/array_in_place.carbon b/toolchain/check/testdata/array/array_in_place.carbon
index a49fc8769ea2..906a73394e86 100644
--- a/toolchain/check/testdata/array/array_in_place.carbon
+++ b/toolchain/check/testdata/array/array_in_place.carbon
@@ -43,6 +43,7 @@ fn G() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/array_vs_tuple.carbon b/toolchain/check/testdata/array/array_vs_tuple.carbon
index db72c1074038..f8f35442da0a 100644
--- a/toolchain/check/testdata/array/array_vs_tuple.carbon
+++ b/toolchain/check/testdata/array/array_vs_tuple.carbon
@@ -43,6 +43,7 @@ fn G() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/assign_return_value.carbon b/toolchain/check/testdata/array/assign_return_value.carbon
index 0e7eb9c13984..c34c5012ae97 100644
--- a/toolchain/check/testdata/array/assign_return_value.carbon
+++ b/toolchain/check/testdata/array/assign_return_value.carbon
@@ -41,6 +41,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/assign_var.carbon b/toolchain/check/testdata/array/assign_var.carbon
index 6012794da1d5..ce6306b57f07 100644
--- a/toolchain/check/testdata/array/assign_var.carbon
+++ b/toolchain/check/testdata/array/assign_var.carbon
@@ -37,6 +37,7 @@ var b: [i32; 3] = a;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/base.carbon b/toolchain/check/testdata/array/base.carbon
index ae72a9f381f8..a10d8698f964 100644
--- a/toolchain/check/testdata/array/base.carbon
+++ b/toolchain/check/testdata/array/base.carbon
@@ -53,6 +53,7 @@ var c: [(); 5] = ((), (), (), (), (),);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/canonicalize_index.carbon b/toolchain/check/testdata/array/canonicalize_index.carbon
index ad8c6d962801..88df6961cc90 100644
--- a/toolchain/check/testdata/array/canonicalize_index.carbon
+++ b/toolchain/check/testdata/array/canonicalize_index.carbon
@@ -39,6 +39,7 @@ let b: [i32; 3]* = &a;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/fail_bound_negative.carbon b/toolchain/check/testdata/array/fail_bound_negative.carbon
index 9262583098aa..8ba5147eed3f 100644
--- a/toolchain/check/testdata/array/fail_bound_negative.carbon
+++ b/toolchain/check/testdata/array/fail_bound_negative.carbon
@@ -35,6 +35,7 @@ var a: [i32; Negate(1)];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/fail_bound_overflow.carbon b/toolchain/check/testdata/array/fail_bound_overflow.carbon
index 380d9648dddb..db7ae434657b 100644
--- a/toolchain/check/testdata/array/fail_bound_overflow.carbon
+++ b/toolchain/check/testdata/array/fail_bound_overflow.carbon
@@ -64,6 +64,7 @@ var b: [1; 39999999999999999993];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/fail_incomplete_element.carbon b/toolchain/check/testdata/array/fail_incomplete_element.carbon
index 78947d0ca791..bba27999a0c9 100644
--- a/toolchain/check/testdata/array/fail_incomplete_element.carbon
+++ b/toolchain/check/testdata/array/fail_incomplete_element.carbon
@@ -37,6 +37,7 @@ var p: Incomplete* = &a[0];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/fail_invalid_type.carbon b/toolchain/check/testdata/array/fail_invalid_type.carbon
index 340b9d8995c8..a47ab2d36b87 100644
--- a/toolchain/check/testdata/array/fail_invalid_type.carbon
+++ b/toolchain/check/testdata/array/fail_invalid_type.carbon
@@ -48,6 +48,7 @@ var a: [1; 1];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/fail_out_of_bound.carbon b/toolchain/check/testdata/array/fail_out_of_bound.carbon
index a083c7e4d3ba..9f96538fc788 100644
--- a/toolchain/check/testdata/array/fail_out_of_bound.carbon
+++ b/toolchain/check/testdata/array/fail_out_of_bound.carbon
@@ -35,6 +35,7 @@ var a: [i32; 1] = (1, 2, 3);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/fail_out_of_bound_non_literal.carbon b/toolchain/check/testdata/array/fail_out_of_bound_non_literal.carbon
index 2d5b1e84030c..09fe2781b645 100644
--- a/toolchain/check/testdata/array/fail_out_of_bound_non_literal.carbon
+++ b/toolchain/check/testdata/array/fail_out_of_bound_non_literal.carbon
@@ -40,6 +40,7 @@ var b: i32 = a[{.index = 3}.index];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/fail_type_mismatch.carbon b/toolchain/check/testdata/array/fail_type_mismatch.carbon
index 8ead3a7b4951..ee800c28a459 100644
--- a/toolchain/check/testdata/array/fail_type_mismatch.carbon
+++ b/toolchain/check/testdata/array/fail_type_mismatch.carbon
@@ -89,6 +89,7 @@ var d: [i32; 3] = t2;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/function_param.carbon b/toolchain/check/testdata/array/function_param.carbon
index ce6c240736d2..ccee40a57fdb 100644
--- a/toolchain/check/testdata/array/function_param.carbon
+++ b/toolchain/check/testdata/array/function_param.carbon
@@ -44,6 +44,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/generic_empty.carbon b/toolchain/check/testdata/array/generic_empty.carbon
index 5ad21c5736be..6204b08b37df 100644
--- a/toolchain/check/testdata/array/generic_empty.carbon
+++ b/toolchain/check/testdata/array/generic_empty.carbon
@@ -34,6 +34,7 @@ fn G(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/index_not_literal.carbon b/toolchain/check/testdata/array/index_not_literal.carbon
index a261952196f8..7aea8be1b629 100644
--- a/toolchain/check/testdata/array/index_not_literal.carbon
+++ b/toolchain/check/testdata/array/index_not_literal.carbon
@@ -37,6 +37,7 @@ var b: i32 = a[{.index = 2}.index];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/array/nine_elements.carbon b/toolchain/check/testdata/array/nine_elements.carbon
index ff32df7596a6..6b898dc1ed6c 100644
--- a/toolchain/check/testdata/array/nine_elements.carbon
+++ b/toolchain/check/testdata/array/nine_elements.carbon
@@ -40,6 +40,7 @@ var a: [i32; 9] = (1, 2, 3, 4, 5, 6, 7, 8, 9);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/as/adapter_conversion.carbon b/toolchain/check/testdata/as/adapter_conversion.carbon
index ec98ea37f006..e7cad908a427 100644
--- a/toolchain/check/testdata/as/adapter_conversion.carbon
+++ b/toolchain/check/testdata/as/adapter_conversion.carbon
@@ -134,6 +134,7 @@ var b: B = {.x = 1} as B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -274,6 +275,7 @@ var b: B = {.x = 1} as B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -349,6 +351,7 @@ var b: B = {.x = 1} as B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -443,6 +446,7 @@ var b: B = {.x = 1} as B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -577,6 +581,7 @@ var b: B = {.x = 1} as B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/as/as_type.carbon b/toolchain/check/testdata/as/as_type.carbon
index 1efb4fbed761..a9c74b197fb1 100644
--- a/toolchain/check/testdata/as/as_type.carbon
+++ b/toolchain/check/testdata/as/as_type.carbon
@@ -28,6 +28,7 @@ let t: type = (i32, i32) as type;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/as/basic.carbon b/toolchain/check/testdata/as/basic.carbon
index 837936c4516b..7685b1c77c64 100644
--- a/toolchain/check/testdata/as/basic.carbon
+++ b/toolchain/check/testdata/as/basic.carbon
@@ -31,6 +31,7 @@ fn Main() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/as/fail_no_conversion.carbon b/toolchain/check/testdata/as/fail_no_conversion.carbon
index ac3d148fea00..0392eeafaf05 100644
--- a/toolchain/check/testdata/as/fail_no_conversion.carbon
+++ b/toolchain/check/testdata/as/fail_no_conversion.carbon
@@ -54,6 +54,7 @@ let n: (i32, i32) = 1 as (i32, i32);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/as/fail_not_type.carbon b/toolchain/check/testdata/as/fail_not_type.carbon
index 9948d99e5057..f04de0c2c3f8 100644
--- a/toolchain/check/testdata/as/fail_not_type.carbon
+++ b/toolchain/check/testdata/as/fail_not_type.carbon
@@ -52,6 +52,7 @@ let n: i32 = 1 as 2;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/as/identity.carbon b/toolchain/check/testdata/as/identity.carbon
index badf6e283535..4a9b5ea45b22 100644
--- a/toolchain/check/testdata/as/identity.carbon
+++ b/toolchain/check/testdata/as/identity.carbon
@@ -54,6 +54,7 @@ fn Initializing() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/as/overloaded.carbon b/toolchain/check/testdata/as/overloaded.carbon
index 5b3bd0345f4a..dd111e2bfb53 100644
--- a/toolchain/check/testdata/as/overloaded.carbon
+++ b/toolchain/check/testdata/as/overloaded.carbon
@@ -74,6 +74,7 @@ let n: i32 = ((4 as i32) as X) as i32;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/builtin_types.carbon b/toolchain/check/testdata/basics/builtin_types.carbon
index abf6d2f74418..353e15f50f26 100644
--- a/toolchain/check/testdata/basics/builtin_types.carbon
+++ b/toolchain/check/testdata/basics/builtin_types.carbon
@@ -37,6 +37,7 @@ var test_type: type = i32;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/fail_bad_run.carbon b/toolchain/check/testdata/basics/fail_bad_run.carbon
index cd96dba4dea7..8594408782ed 100644
--- a/toolchain/check/testdata/basics/fail_bad_run.carbon
+++ b/toolchain/check/testdata/basics/fail_bad_run.carbon
@@ -33,6 +33,7 @@ fn Run() -> String {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/fail_bad_run_2.carbon b/toolchain/check/testdata/basics/fail_bad_run_2.carbon
index f9df8625ade3..f2365e9f3a31 100644
--- a/toolchain/check/testdata/basics/fail_bad_run_2.carbon
+++ b/toolchain/check/testdata/basics/fail_bad_run_2.carbon
@@ -31,6 +31,7 @@ fn Run(n: i32) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/fail_non_type_as_type.carbon b/toolchain/check/testdata/basics/fail_non_type_as_type.carbon
index 322a8d7fdf19..4537565eb47d 100644
--- a/toolchain/check/testdata/basics/fail_non_type_as_type.carbon
+++ b/toolchain/check/testdata/basics/fail_non_type_as_type.carbon
@@ -48,6 +48,7 @@ var x: type = 42;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/fail_numeric_literal_overflow.carbon b/toolchain/check/testdata/basics/fail_numeric_literal_overflow.carbon
index e227bbabb8f8..ef2d393c79b4 100644
--- a/toolchain/check/testdata/basics/fail_numeric_literal_overflow.carbon
+++ b/toolchain/check/testdata/basics/fail_numeric_literal_overflow.carbon
@@ -57,6 +57,7 @@ let e: f64 = 5.0e39999999999999999993;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/fail_qualifier_unsupported.carbon b/toolchain/check/testdata/basics/fail_qualifier_unsupported.carbon
index e2dc134fd759..149b72f21446 100644
--- a/toolchain/check/testdata/basics/fail_qualifier_unsupported.carbon
+++ b/toolchain/check/testdata/basics/fail_qualifier_unsupported.carbon
@@ -30,6 +30,7 @@ var y: i32 = x.b;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/multifile.carbon b/toolchain/check/testdata/basics/multifile.carbon
index 3a195adba8f7..0e37089ad685 100644
--- a/toolchain/check/testdata/basics/multifile.carbon
+++ b/toolchain/check/testdata/basics/multifile.carbon
@@ -33,6 +33,7 @@ fn B() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -68,6 +69,7 @@ fn B() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/numeric_literals.carbon b/toolchain/check/testdata/basics/numeric_literals.carbon
index 7a3a0954224d..03e400d249ec 100644
--- a/toolchain/check/testdata/basics/numeric_literals.carbon
+++ b/toolchain/check/testdata/basics/numeric_literals.carbon
@@ -75,6 +75,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/parens.carbon b/toolchain/check/testdata/basics/parens.carbon
index 40417c4730b7..61125c9f7d8c 100644
--- a/toolchain/check/testdata/basics/parens.carbon
+++ b/toolchain/check/testdata/basics/parens.carbon
@@ -29,6 +29,7 @@ var b: i32 = ((2));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/run.carbon b/toolchain/check/testdata/basics/run.carbon
index a7e275cf2e7b..1f61027a2d95 100644
--- a/toolchain/check/testdata/basics/run.carbon
+++ b/toolchain/check/testdata/basics/run.carbon
@@ -25,6 +25,7 @@ fn Run() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/run_i32.carbon b/toolchain/check/testdata/basics/run_i32.carbon
index 8e657962c5bb..04c2ea8bddab 100644
--- a/toolchain/check/testdata/basics/run_i32.carbon
+++ b/toolchain/check/testdata/basics/run_i32.carbon
@@ -29,6 +29,7 @@ fn Run() -> i32 { return 0; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/basics/type_literals.carbon b/toolchain/check/testdata/basics/type_literals.carbon
index c828b9d0e029..7d72cc9d5868 100644
--- a/toolchain/check/testdata/basics/type_literals.carbon
+++ b/toolchain/check/testdata/basics/type_literals.carbon
@@ -149,6 +149,7 @@ var test_f128: f128;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -225,6 +226,7 @@ var test_f128: f128;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/big_int/make_type.carbon b/toolchain/check/testdata/builtins/big_int/make_type.carbon
index 783f11bfd762..d28fea742add 100644
--- a/toolchain/check/testdata/builtins/big_int/make_type.carbon
+++ b/toolchain/check/testdata/builtins/big_int/make_type.carbon
@@ -37,6 +37,7 @@ var i: BigInt();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -76,6 +77,7 @@ var i: BigInt();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/bool/make_type.carbon b/toolchain/check/testdata/builtins/bool/make_type.carbon
index bcc67090aee4..0f96a41f36ac 100644
--- a/toolchain/check/testdata/builtins/bool/make_type.carbon
+++ b/toolchain/check/testdata/builtins/bool/make_type.carbon
@@ -37,6 +37,7 @@ var b: Bool() = false;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -77,6 +78,7 @@ var b: Bool() = false;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/add.carbon b/toolchain/check/testdata/builtins/float/add.carbon
index 069b49d6242f..1c0f625aa2c4 100644
--- a/toolchain/check/testdata/builtins/float/add.carbon
+++ b/toolchain/check/testdata/builtins/float/add.carbon
@@ -74,6 +74,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -210,6 +211,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/div.carbon b/toolchain/check/testdata/builtins/float/div.carbon
index 85c6137c132c..6abdc3856c5c 100644
--- a/toolchain/check/testdata/builtins/float/div.carbon
+++ b/toolchain/check/testdata/builtins/float/div.carbon
@@ -80,6 +80,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -240,6 +241,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/eq.carbon b/toolchain/check/testdata/builtins/float/eq.carbon
index 153918b2074b..00b388fa17d1 100644
--- a/toolchain/check/testdata/builtins/float/eq.carbon
+++ b/toolchain/check/testdata/builtins/float/eq.carbon
@@ -68,6 +68,7 @@ fn WrongResult(a: f64, b: f64) -> f64 = "float.eq";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -248,6 +249,7 @@ fn WrongResult(a: f64, b: f64) -> f64 = "float.eq";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/greater.carbon b/toolchain/check/testdata/builtins/float/greater.carbon
index 5ac20481f95f..50e00d7a5fca 100644
--- a/toolchain/check/testdata/builtins/float/greater.carbon
+++ b/toolchain/check/testdata/builtins/float/greater.carbon
@@ -67,6 +67,7 @@ fn RuntimeCall(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/greater_eq.carbon b/toolchain/check/testdata/builtins/float/greater_eq.carbon
index c8e23c333323..84a446300219 100644
--- a/toolchain/check/testdata/builtins/float/greater_eq.carbon
+++ b/toolchain/check/testdata/builtins/float/greater_eq.carbon
@@ -67,6 +67,7 @@ fn RuntimeCall(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/less.carbon b/toolchain/check/testdata/builtins/float/less.carbon
index a66d9956e67a..22eec2cd2c70 100644
--- a/toolchain/check/testdata/builtins/float/less.carbon
+++ b/toolchain/check/testdata/builtins/float/less.carbon
@@ -67,6 +67,7 @@ fn RuntimeCall(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/less_eq.carbon b/toolchain/check/testdata/builtins/float/less_eq.carbon
index a0f293324223..a8cb49eb4063 100644
--- a/toolchain/check/testdata/builtins/float/less_eq.carbon
+++ b/toolchain/check/testdata/builtins/float/less_eq.carbon
@@ -67,6 +67,7 @@ fn RuntimeCall(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/make_type.carbon b/toolchain/check/testdata/builtins/float/make_type.carbon
index c8bdb3e4ef75..ef09f5cddd1e 100644
--- a/toolchain/check/testdata/builtins/float/make_type.carbon
+++ b/toolchain/check/testdata/builtins/float/make_type.carbon
@@ -62,6 +62,7 @@ var dyn: Float(dyn_size);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -118,6 +119,7 @@ var dyn: Float(dyn_size);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -199,6 +201,7 @@ var dyn: Float(dyn_size);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/mul.carbon b/toolchain/check/testdata/builtins/float/mul.carbon
index d1dd7735229d..3a8738327064 100644
--- a/toolchain/check/testdata/builtins/float/mul.carbon
+++ b/toolchain/check/testdata/builtins/float/mul.carbon
@@ -74,6 +74,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -210,6 +211,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/negate.carbon b/toolchain/check/testdata/builtins/float/negate.carbon
index 82fb60758240..7ebd932f6f0f 100644
--- a/toolchain/check/testdata/builtins/float/negate.carbon
+++ b/toolchain/check/testdata/builtins/float/negate.carbon
@@ -94,6 +94,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -220,6 +221,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/neq.carbon b/toolchain/check/testdata/builtins/float/neq.carbon
index 000eda85b1cb..fc879eb94a19 100644
--- a/toolchain/check/testdata/builtins/float/neq.carbon
+++ b/toolchain/check/testdata/builtins/float/neq.carbon
@@ -68,6 +68,7 @@ fn WrongResult(a: f64, b: f64) -> f64 = "float.neq";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -248,6 +249,7 @@ fn WrongResult(a: f64, b: f64) -> f64 = "float.neq";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/float/sub.carbon b/toolchain/check/testdata/builtins/float/sub.carbon
index f03074aedc52..c0f6e3bc5e37 100644
--- a/toolchain/check/testdata/builtins/float/sub.carbon
+++ b/toolchain/check/testdata/builtins/float/sub.carbon
@@ -74,6 +74,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -210,6 +211,7 @@ fn RuntimeCallBadReturnType(a: f64, b: f64) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/and.carbon b/toolchain/check/testdata/builtins/int/and.carbon
index 4716b17f363b..89686369b772 100644
--- a/toolchain/check/testdata/builtins/int/and.carbon
+++ b/toolchain/check/testdata/builtins/int/and.carbon
@@ -44,6 +44,7 @@ fn RuntimeCall(a: i32, b: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/complement.carbon b/toolchain/check/testdata/builtins/int/complement.carbon
index ae206411ce5c..94df15896cb6 100644
--- a/toolchain/check/testdata/builtins/int/complement.carbon
+++ b/toolchain/check/testdata/builtins/int/complement.carbon
@@ -48,6 +48,7 @@ fn RuntimeCall(a: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/eq.carbon b/toolchain/check/testdata/builtins/int/eq.carbon
index e1a0dd7b1517..002a7853c6fa 100644
--- a/toolchain/check/testdata/builtins/int/eq.carbon
+++ b/toolchain/check/testdata/builtins/int/eq.carbon
@@ -67,6 +67,7 @@ fn WrongResult(a: i32, b: i32) -> i32 = "int.eq";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -242,6 +243,7 @@ fn WrongResult(a: i32, b: i32) -> i32 = "int.eq";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/greater.carbon b/toolchain/check/testdata/builtins/int/greater.carbon
index 26209d8635e9..55f21d111f25 100644
--- a/toolchain/check/testdata/builtins/int/greater.carbon
+++ b/toolchain/check/testdata/builtins/int/greater.carbon
@@ -66,6 +66,7 @@ fn RuntimeCall(a: i32, b: i32) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/greater_eq.carbon b/toolchain/check/testdata/builtins/int/greater_eq.carbon
index d7fa8ac249c8..71c2814a79b9 100644
--- a/toolchain/check/testdata/builtins/int/greater_eq.carbon
+++ b/toolchain/check/testdata/builtins/int/greater_eq.carbon
@@ -66,6 +66,7 @@ fn RuntimeCall(a: i32, b: i32) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/left_shift.carbon b/toolchain/check/testdata/builtins/int/left_shift.carbon
index 171caa9acf7d..efba95cd6144 100644
--- a/toolchain/check/testdata/builtins/int/left_shift.carbon
+++ b/toolchain/check/testdata/builtins/int/left_shift.carbon
@@ -88,6 +88,7 @@ let negative: i32 = LeftShift(1, Negate(1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -221,6 +222,7 @@ let negative: i32 = LeftShift(1, Negate(1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/less.carbon b/toolchain/check/testdata/builtins/int/less.carbon
index 871bcf80b6f9..492f887c039f 100644
--- a/toolchain/check/testdata/builtins/int/less.carbon
+++ b/toolchain/check/testdata/builtins/int/less.carbon
@@ -66,6 +66,7 @@ fn RuntimeCall(a: i32, b: i32) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/less_eq.carbon b/toolchain/check/testdata/builtins/int/less_eq.carbon
index 993821202734..3fe6b10ad523 100644
--- a/toolchain/check/testdata/builtins/int/less_eq.carbon
+++ b/toolchain/check/testdata/builtins/int/less_eq.carbon
@@ -66,6 +66,7 @@ fn RuntimeCall(a: i32, b: i32) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/make_type_32.carbon b/toolchain/check/testdata/builtins/int/make_type_32.carbon
index d151bbdc843d..7fd15b52c34f 100644
--- a/toolchain/check/testdata/builtins/int/make_type_32.carbon
+++ b/toolchain/check/testdata/builtins/int/make_type_32.carbon
@@ -37,6 +37,7 @@ var i: Int() = 0;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -77,6 +78,7 @@ var i: Int() = 0;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/make_type_signed.carbon b/toolchain/check/testdata/builtins/int/make_type_signed.carbon
index e7f286df556a..41974206d256 100644
--- a/toolchain/check/testdata/builtins/int/make_type_signed.carbon
+++ b/toolchain/check/testdata/builtins/int/make_type_signed.carbon
@@ -87,6 +87,7 @@ var m: Int(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -152,6 +153,7 @@ var m: Int(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -294,6 +296,7 @@ var m: Int(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -342,6 +345,7 @@ var m: Int(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -411,6 +415,7 @@ var m: Int(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/make_type_unsigned.carbon b/toolchain/check/testdata/builtins/int/make_type_unsigned.carbon
index d9a7d41f9f64..eddd7814d103 100644
--- a/toolchain/check/testdata/builtins/int/make_type_unsigned.carbon
+++ b/toolchain/check/testdata/builtins/int/make_type_unsigned.carbon
@@ -87,6 +87,7 @@ var m: UInt(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -152,6 +153,7 @@ var m: UInt(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -294,6 +296,7 @@ var m: UInt(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -342,6 +345,7 @@ var m: UInt(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -411,6 +415,7 @@ var m: UInt(1000000000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/neq.carbon b/toolchain/check/testdata/builtins/int/neq.carbon
index fce1a3dc9921..5eb4dfa29ead 100644
--- a/toolchain/check/testdata/builtins/int/neq.carbon
+++ b/toolchain/check/testdata/builtins/int/neq.carbon
@@ -58,6 +58,7 @@ fn RuntimeCall(a: i32, b: i32) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/or.carbon b/toolchain/check/testdata/builtins/int/or.carbon
index 2934eb479ed8..2d9edfd00dd4 100644
--- a/toolchain/check/testdata/builtins/int/or.carbon
+++ b/toolchain/check/testdata/builtins/int/or.carbon
@@ -44,6 +44,7 @@ fn RuntimeCall(a: i32, b: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/right_shift.carbon b/toolchain/check/testdata/builtins/int/right_shift.carbon
index 9d623e752a20..7f05167f3a4d 100644
--- a/toolchain/check/testdata/builtins/int/right_shift.carbon
+++ b/toolchain/check/testdata/builtins/int/right_shift.carbon
@@ -89,6 +89,7 @@ let negative: i32 = RightShift(1, Negate(1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -225,6 +226,7 @@ let negative: i32 = RightShift(1, Negate(1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -377,6 +379,7 @@ let negative: i32 = RightShift(1, Negate(1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/sadd.carbon b/toolchain/check/testdata/builtins/int/sadd.carbon
index 0c5638d5ccd9..ae295cdd1783 100644
--- a/toolchain/check/testdata/builtins/int/sadd.carbon
+++ b/toolchain/check/testdata/builtins/int/sadd.carbon
@@ -114,6 +114,7 @@ let b: i32 = Add(0x7FFFFFFF, 1);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -255,6 +256,7 @@ let b: i32 = Add(0x7FFFFFFF, 1);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -547,6 +549,7 @@ let b: i32 = Add(0x7FFFFFFF, 1);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/sdiv.carbon b/toolchain/check/testdata/builtins/int/sdiv.carbon
index b8741da54a2b..a3eeabd7453f 100644
--- a/toolchain/check/testdata/builtins/int/sdiv.carbon
+++ b/toolchain/check/testdata/builtins/int/sdiv.carbon
@@ -82,6 +82,7 @@ let b: i32 = Div(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -214,6 +215,7 @@ let b: i32 = Div(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -392,6 +394,7 @@ let b: i32 = Div(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/smod.carbon b/toolchain/check/testdata/builtins/int/smod.carbon
index 7e0bf41c7cad..3744a3a27b5d 100644
--- a/toolchain/check/testdata/builtins/int/smod.carbon
+++ b/toolchain/check/testdata/builtins/int/smod.carbon
@@ -85,6 +85,7 @@ let b: i32 = Mod(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -218,6 +219,7 @@ let b: i32 = Mod(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -396,6 +398,7 @@ let b: i32 = Mod(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/smul.carbon b/toolchain/check/testdata/builtins/int/smul.carbon
index 0ecee8930e2f..692871c1036e 100644
--- a/toolchain/check/testdata/builtins/int/smul.carbon
+++ b/toolchain/check/testdata/builtins/int/smul.carbon
@@ -56,6 +56,7 @@ let b: i32 = Mul(0x8000, 0x10000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -184,6 +185,7 @@ let b: i32 = Mul(0x8000, 0x10000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/snegate.carbon b/toolchain/check/testdata/builtins/int/snegate.carbon
index a62afd8aa9ae..4ff6d8ec21ab 100644
--- a/toolchain/check/testdata/builtins/int/snegate.carbon
+++ b/toolchain/check/testdata/builtins/int/snegate.carbon
@@ -142,6 +142,7 @@ let b: i32 = Negate(Sub(Negate(0x7FFFFFFF), 1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -287,6 +288,7 @@ let b: i32 = Negate(Sub(Negate(0x7FFFFFFF), 1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -540,6 +542,7 @@ let b: i32 = Negate(Sub(Negate(0x7FFFFFFF), 1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/ssub.carbon b/toolchain/check/testdata/builtins/int/ssub.carbon
index 1b4d801bdab4..eef053492b34 100644
--- a/toolchain/check/testdata/builtins/int/ssub.carbon
+++ b/toolchain/check/testdata/builtins/int/ssub.carbon
@@ -57,6 +57,7 @@ let c: i32 = Sub(Sub(0, 0x7FFFFFFF), 2);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -186,6 +187,7 @@ let c: i32 = Sub(Sub(0, 0x7FFFFFFF), 2);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/uadd.carbon b/toolchain/check/testdata/builtins/int/uadd.carbon
index 5805455601d9..d31693dd12f1 100644
--- a/toolchain/check/testdata/builtins/int/uadd.carbon
+++ b/toolchain/check/testdata/builtins/int/uadd.carbon
@@ -111,6 +111,7 @@ let b: i32 = Add(0x7FFFFFFF, 1);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -252,6 +253,7 @@ let b: i32 = Add(0x7FFFFFFF, 1);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -544,6 +546,7 @@ let b: i32 = Add(0x7FFFFFFF, 1);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/udiv.carbon b/toolchain/check/testdata/builtins/int/udiv.carbon
index d8749a2b60b2..3b287a8ad977 100644
--- a/toolchain/check/testdata/builtins/int/udiv.carbon
+++ b/toolchain/check/testdata/builtins/int/udiv.carbon
@@ -78,6 +78,7 @@ let b: i32 = Div(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -211,6 +212,7 @@ let b: i32 = Div(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -389,6 +391,7 @@ let b: i32 = Div(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/umod.carbon b/toolchain/check/testdata/builtins/int/umod.carbon
index a61e107d5d63..ca6d95694fcd 100644
--- a/toolchain/check/testdata/builtins/int/umod.carbon
+++ b/toolchain/check/testdata/builtins/int/umod.carbon
@@ -80,6 +80,7 @@ let b: i32 = Mod(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -213,6 +214,7 @@ let b: i32 = Mod(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -391,6 +393,7 @@ let b: i32 = Mod(0, 0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/umul.carbon b/toolchain/check/testdata/builtins/int/umul.carbon
index 077d8ae660a4..0394d5830df1 100644
--- a/toolchain/check/testdata/builtins/int/umul.carbon
+++ b/toolchain/check/testdata/builtins/int/umul.carbon
@@ -53,6 +53,7 @@ let b: i32 = Mul(0x8000, 0x10000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -181,6 +182,7 @@ let b: i32 = Mul(0x8000, 0x10000);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/unegate.carbon b/toolchain/check/testdata/builtins/int/unegate.carbon
index fe2f88561954..9efa74afb789 100644
--- a/toolchain/check/testdata/builtins/int/unegate.carbon
+++ b/toolchain/check/testdata/builtins/int/unegate.carbon
@@ -138,6 +138,7 @@ let b: i32 = Negate(Sub(Negate(0x7FFFFFFF), 1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -283,6 +284,7 @@ let b: i32 = Negate(Sub(Negate(0x7FFFFFFF), 1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -536,6 +538,7 @@ let b: i32 = Negate(Sub(Negate(0x7FFFFFFF), 1));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/usub.carbon b/toolchain/check/testdata/builtins/int/usub.carbon
index a80ccbb1a942..8555026d26f7 100644
--- a/toolchain/check/testdata/builtins/int/usub.carbon
+++ b/toolchain/check/testdata/builtins/int/usub.carbon
@@ -54,6 +54,7 @@ let c: i32 = Sub(Sub(0, 0x7FFFFFFF), 2);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -183,6 +184,7 @@ let c: i32 = Sub(Sub(0, 0x7FFFFFFF), 2);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/int/xor.carbon b/toolchain/check/testdata/builtins/int/xor.carbon
index 77daf634c7c8..4e17a7fbf663 100644
--- a/toolchain/check/testdata/builtins/int/xor.carbon
+++ b/toolchain/check/testdata/builtins/int/xor.carbon
@@ -44,6 +44,7 @@ fn RuntimeCall(a: i32, b: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/builtins/print.carbon b/toolchain/check/testdata/builtins/print.carbon
index 0c8013f8baf7..4cd379683712 100644
--- a/toolchain/check/testdata/builtins/print.carbon
+++ b/toolchain/check/testdata/builtins/print.carbon
@@ -41,12 +41,13 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %import_ref.1: %Int32.type = import_ref Core//prelude/types, inst+15, loaded [template = constants.%Int32]
-// CHECK:STDOUT:   %import_ref.2: %Print.type.2 = import_ref Core//prelude, inst+48, loaded [template = constants.%Print.2]
+// CHECK:STDOUT:   %import_ref.2: %Print.type.2 = import_ref Core//prelude, inst+49, loaded [template = constants.%Print.2]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
diff --git a/toolchain/check/testdata/class/access_modifers.carbon b/toolchain/check/testdata/class/access_modifers.carbon
index b22def829966..b000fd5bb9cb 100644
--- a/toolchain/check/testdata/class/access_modifers.carbon
+++ b/toolchain/check/testdata/class/access_modifers.carbon
@@ -175,6 +175,7 @@ class A {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -300,6 +301,7 @@ class A {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -371,6 +373,7 @@ class A {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -490,6 +493,7 @@ class A {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -554,6 +558,7 @@ class A {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -631,6 +636,7 @@ class A {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/adapt.carbon b/toolchain/check/testdata/class/adapt.carbon
index c15d14c82158..b57b47c265da 100644
--- a/toolchain/check/testdata/class/adapt.carbon
+++ b/toolchain/check/testdata/class/adapt.carbon
@@ -69,6 +69,7 @@ fn F(a: AdaptNotExtend) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -155,6 +156,7 @@ fn F(a: AdaptNotExtend) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/base.carbon b/toolchain/check/testdata/class/base.carbon
index 368887933710..09b7bda8aac4 100644
--- a/toolchain/check/testdata/class/base.carbon
+++ b/toolchain/check/testdata/class/base.carbon
@@ -67,6 +67,7 @@ fn Access(d: Derived) -> (i32, i32) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/base_field.carbon b/toolchain/check/testdata/class/base_field.carbon
index f6acb815faf8..423403bee33c 100644
--- a/toolchain/check/testdata/class/base_field.carbon
+++ b/toolchain/check/testdata/class/base_field.carbon
@@ -58,6 +58,7 @@ fn Access(p: Derived*) -> i32* {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/base_function_unqualified.carbon b/toolchain/check/testdata/class/base_function_unqualified.carbon
index d2c8916c8218..765cc37498ff 100644
--- a/toolchain/check/testdata/class/base_function_unqualified.carbon
+++ b/toolchain/check/testdata/class/base_function_unqualified.carbon
@@ -50,6 +50,7 @@ fn Derived.H() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/base_method.carbon b/toolchain/check/testdata/class/base_method.carbon
index dc0ae6ad7d22..aaed85c10b3c 100644
--- a/toolchain/check/testdata/class/base_method.carbon
+++ b/toolchain/check/testdata/class/base_method.carbon
@@ -60,6 +60,7 @@ fn Call(p: Derived*) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/base_method_qualified.carbon b/toolchain/check/testdata/class/base_method_qualified.carbon
index 81c9a6356df7..b72c99c832a4 100644
--- a/toolchain/check/testdata/class/base_method_qualified.carbon
+++ b/toolchain/check/testdata/class/base_method_qualified.carbon
@@ -81,6 +81,7 @@ fn PassDerivedToBaseIndirect(p: Derived*) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/base_method_shadow.carbon b/toolchain/check/testdata/class/base_method_shadow.carbon
index 76cde627d4dd..08f252fb5d3e 100644
--- a/toolchain/check/testdata/class/base_method_shadow.carbon
+++ b/toolchain/check/testdata/class/base_method_shadow.carbon
@@ -76,6 +76,7 @@ fn Call(a: A*, b: B*, c: C*, d: D*) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/basic.carbon b/toolchain/check/testdata/class/basic.carbon
index 9e8fb185c8aa..b4c34bd4d9c2 100644
--- a/toolchain/check/testdata/class/basic.carbon
+++ b/toolchain/check/testdata/class/basic.carbon
@@ -54,6 +54,7 @@ fn Run() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/complete_in_member_fn.carbon b/toolchain/check/testdata/class/complete_in_member_fn.carbon
index 5f1089f5d32f..5c79f1a21266 100644
--- a/toolchain/check/testdata/class/complete_in_member_fn.carbon
+++ b/toolchain/check/testdata/class/complete_in_member_fn.carbon
@@ -37,6 +37,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/compound_field.carbon b/toolchain/check/testdata/class/compound_field.carbon
index 36b8e12783ec..4dd135e439b1 100644
--- a/toolchain/check/testdata/class/compound_field.carbon
+++ b/toolchain/check/testdata/class/compound_field.carbon
@@ -76,6 +76,7 @@ fn AccessBaseIndirect(p: Derived*) -> i32* {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/cross_package_import.carbon b/toolchain/check/testdata/class/cross_package_import.carbon
index 9d58e26bf4e1..40cdba5e1043 100644
--- a/toolchain/check/testdata/class/cross_package_import.carbon
+++ b/toolchain/check/testdata/class/cross_package_import.carbon
@@ -114,6 +114,7 @@ var c: Other.C = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -149,6 +150,7 @@ var c: Other.C = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -181,6 +183,7 @@ var c: Other.C = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -219,6 +222,7 @@ var c: Other.C = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -273,6 +277,7 @@ var c: Other.C = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -325,6 +330,7 @@ var c: Other.C = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -385,6 +391,7 @@ var c: Other.C = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/derived_to_base.carbon b/toolchain/check/testdata/class/derived_to_base.carbon
index 7de4441754ce..d8a682982752 100644
--- a/toolchain/check/testdata/class/derived_to_base.carbon
+++ b/toolchain/check/testdata/class/derived_to_base.carbon
@@ -98,6 +98,7 @@ fn ConvertInit() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/extend_adapt.carbon b/toolchain/check/testdata/class/extend_adapt.carbon
index ac5f3806c0f4..b8f46da3f9c3 100644
--- a/toolchain/check/testdata/class/extend_adapt.carbon
+++ b/toolchain/check/testdata/class/extend_adapt.carbon
@@ -127,6 +127,7 @@ class StructAdapter {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -266,6 +267,7 @@ class StructAdapter {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -444,6 +446,7 @@ class StructAdapter {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -607,6 +610,7 @@ class StructAdapter {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_abstract.carbon b/toolchain/check/testdata/class/fail_abstract.carbon
index e887fdcd9016..c2ca87b22d6d 100644
--- a/toolchain/check/testdata/class/fail_abstract.carbon
+++ b/toolchain/check/testdata/class/fail_abstract.carbon
@@ -206,6 +206,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -259,6 +260,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -310,6 +312,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -367,6 +370,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -421,6 +425,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -505,6 +510,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -593,6 +599,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -687,6 +694,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -778,6 +786,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -831,6 +840,7 @@ fn CallReturnAbstract() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_adapt_bad_decl.carbon b/toolchain/check/testdata/class/fail_adapt_bad_decl.carbon
index f32ba22144b3..377c5f73945d 100644
--- a/toolchain/check/testdata/class/fail_adapt_bad_decl.carbon
+++ b/toolchain/check/testdata/class/fail_adapt_bad_decl.carbon
@@ -137,6 +137,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -284,6 +285,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -414,6 +416,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -472,6 +475,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_adapt_bad_type.carbon b/toolchain/check/testdata/class/fail_adapt_bad_type.carbon
index deac8d1c0c8e..9d389cf2ec72 100644
--- a/toolchain/check/testdata/class/fail_adapt_bad_type.carbon
+++ b/toolchain/check/testdata/class/fail_adapt_bad_type.carbon
@@ -38,6 +38,7 @@ class AdaptIncomplete {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_adapt_modifiers.carbon b/toolchain/check/testdata/class/fail_adapt_modifiers.carbon
index 0e91378d0731..4b9e32ade20e 100644
--- a/toolchain/check/testdata/class/fail_adapt_modifiers.carbon
+++ b/toolchain/check/testdata/class/fail_adapt_modifiers.carbon
@@ -78,6 +78,7 @@ class C5 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_adapt_with_base.carbon b/toolchain/check/testdata/class/fail_adapt_with_base.carbon
index b86c5676165d..2c4c8ea32edd 100644
--- a/toolchain/check/testdata/class/fail_adapt_with_base.carbon
+++ b/toolchain/check/testdata/class/fail_adapt_with_base.carbon
@@ -39,6 +39,7 @@ base class AdaptWithVirtual {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_adapt_with_subobjects.carbon b/toolchain/check/testdata/class/fail_adapt_with_subobjects.carbon
index 38d960b3663b..d491ad8aff38 100644
--- a/toolchain/check/testdata/class/fail_adapt_with_subobjects.carbon
+++ b/toolchain/check/testdata/class/fail_adapt_with_subobjects.carbon
@@ -96,6 +96,7 @@ class AdaptWithBaseAndFields {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -157,6 +158,7 @@ class AdaptWithBaseAndFields {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -240,6 +242,7 @@ class AdaptWithBaseAndFields {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_addr_not_self.carbon b/toolchain/check/testdata/class/fail_addr_not_self.carbon
index 7cbdfb854b16..7a3ac2f4d2c2 100644
--- a/toolchain/check/testdata/class/fail_addr_not_self.carbon
+++ b/toolchain/check/testdata/class/fail_addr_not_self.carbon
@@ -44,6 +44,7 @@ class Class {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_addr_self.carbon b/toolchain/check/testdata/class/fail_addr_self.carbon
index 091a9243b896..20722a4e2958 100644
--- a/toolchain/check/testdata/class/fail_addr_self.carbon
+++ b/toolchain/check/testdata/class/fail_addr_self.carbon
@@ -58,6 +58,7 @@ fn F(c: Class, p: Class*) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_base_bad_type.carbon b/toolchain/check/testdata/class/fail_base_bad_type.carbon
index 5bab8a1e6b4f..4209671b0434 100644
--- a/toolchain/check/testdata/class/fail_base_bad_type.carbon
+++ b/toolchain/check/testdata/class/fail_base_bad_type.carbon
@@ -198,6 +198,7 @@ fn AccessMemberWithInvalidBaseFinal_NoMember(p: DeriveFromFinal*) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -291,6 +292,7 @@ fn AccessMemberWithInvalidBaseFinal_NoMember(p: DeriveFromFinal*) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -458,6 +460,7 @@ fn AccessMemberWithInvalidBaseFinal_NoMember(p: DeriveFromFinal*) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -658,6 +661,7 @@ fn AccessMemberWithInvalidBaseFinal_NoMember(p: DeriveFromFinal*) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -861,6 +865,7 @@ fn AccessMemberWithInvalidBaseFinal_NoMember(p: DeriveFromFinal*) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1063,6 +1068,7 @@ fn AccessMemberWithInvalidBaseFinal_NoMember(p: DeriveFromFinal*) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1250,6 +1256,7 @@ fn AccessMemberWithInvalidBaseFinal_NoMember(p: DeriveFromFinal*) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_base_method_define.carbon b/toolchain/check/testdata/class/fail_base_method_define.carbon
index 4d39d8566c18..0367248ba071 100644
--- a/toolchain/check/testdata/class/fail_base_method_define.carbon
+++ b/toolchain/check/testdata/class/fail_base_method_define.carbon
@@ -61,6 +61,7 @@ fn D.C.F() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_base_modifiers.carbon b/toolchain/check/testdata/class/fail_base_modifiers.carbon
index c3a1516118a4..2652f8404e59 100644
--- a/toolchain/check/testdata/class/fail_base_modifiers.carbon
+++ b/toolchain/check/testdata/class/fail_base_modifiers.carbon
@@ -78,6 +78,7 @@ class C4 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_base_no_extend.carbon b/toolchain/check/testdata/class/fail_base_no_extend.carbon
index 65094b337430..46bd442732f0 100644
--- a/toolchain/check/testdata/class/fail_base_no_extend.carbon
+++ b/toolchain/check/testdata/class/fail_base_no_extend.carbon
@@ -38,6 +38,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_base_repeated.carbon b/toolchain/check/testdata/class/fail_base_repeated.carbon
index 6ec9d805c320..a96d64196a14 100644
--- a/toolchain/check/testdata/class/fail_base_repeated.carbon
+++ b/toolchain/check/testdata/class/fail_base_repeated.carbon
@@ -59,6 +59,7 @@ class D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_base_unbound.carbon b/toolchain/check/testdata/class/fail_base_unbound.carbon
index 654dd7500ad0..eaa170e32634 100644
--- a/toolchain/check/testdata/class/fail_base_unbound.carbon
+++ b/toolchain/check/testdata/class/fail_base_unbound.carbon
@@ -42,6 +42,7 @@ let b: B = C.base;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_compound_type_mismatch.carbon b/toolchain/check/testdata/class/fail_compound_type_mismatch.carbon
index 827fee42f81a..f171e97decf5 100644
--- a/toolchain/check/testdata/class/fail_compound_type_mismatch.carbon
+++ b/toolchain/check/testdata/class/fail_compound_type_mismatch.carbon
@@ -72,6 +72,7 @@ fn AccessBInA(a: A) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_convert_to_invalid.carbon b/toolchain/check/testdata/class/fail_convert_to_invalid.carbon
index 05a011043156..39cd5f86e4f9 100644
--- a/toolchain/check/testdata/class/fail_convert_to_invalid.carbon
+++ b/toolchain/check/testdata/class/fail_convert_to_invalid.carbon
@@ -37,6 +37,7 @@ fn Make() -> C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_derived_to_base.carbon b/toolchain/check/testdata/class/fail_derived_to_base.carbon
index 7469b248ad52..53713318c61a 100644
--- a/toolchain/check/testdata/class/fail_derived_to_base.carbon
+++ b/toolchain/check/testdata/class/fail_derived_to_base.carbon
@@ -103,6 +103,7 @@ fn ConvertIncomplete(p: Incomplete*) -> A2* { return p; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_extend_cycle.carbon b/toolchain/check/testdata/class/fail_extend_cycle.carbon
index 8f4e78ea8504..1d0d177e9468 100644
--- a/toolchain/check/testdata/class/fail_extend_cycle.carbon
+++ b/toolchain/check/testdata/class/fail_extend_cycle.carbon
@@ -54,6 +54,7 @@ base class A {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_field_modifiers.carbon b/toolchain/check/testdata/class/fail_field_modifiers.carbon
index 9bb3f1e2e9e8..2b77fa82e36b 100644
--- a/toolchain/check/testdata/class/fail_field_modifiers.carbon
+++ b/toolchain/check/testdata/class/fail_field_modifiers.carbon
@@ -56,6 +56,7 @@ class Class {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_generic_method.carbon b/toolchain/check/testdata/class/fail_generic_method.carbon
index e6b1af786375..500c210945f5 100644
--- a/toolchain/check/testdata/class/fail_generic_method.carbon
+++ b/toolchain/check/testdata/class/fail_generic_method.carbon
@@ -61,6 +61,7 @@ fn Class(N:! i32).F[self: Self](n: T) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_import_misuses.carbon b/toolchain/check/testdata/class/fail_import_misuses.carbon
index 66d7bb809536..e7876fd228fb 100644
--- a/toolchain/check/testdata/class/fail_import_misuses.carbon
+++ b/toolchain/check/testdata/class/fail_import_misuses.carbon
@@ -59,6 +59,7 @@ var a: Incomplete;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -104,6 +105,7 @@ var a: Incomplete;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_incomplete.carbon b/toolchain/check/testdata/class/fail_incomplete.carbon
index 53c7a0b70c28..0f3563d3a6a5 100644
--- a/toolchain/check/testdata/class/fail_incomplete.carbon
+++ b/toolchain/check/testdata/class/fail_incomplete.carbon
@@ -195,6 +195,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -404,6 +405,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_init.carbon b/toolchain/check/testdata/class/fail_init.carbon
index 29e745152415..261e070724a7 100644
--- a/toolchain/check/testdata/class/fail_init.carbon
+++ b/toolchain/check/testdata/class/fail_init.carbon
@@ -59,6 +59,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_init_as_inplace.carbon b/toolchain/check/testdata/class/fail_init_as_inplace.carbon
index 3d9d3f0bd2f5..d95f6081e546 100644
--- a/toolchain/check/testdata/class/fail_init_as_inplace.carbon
+++ b/toolchain/check/testdata/class/fail_init_as_inplace.carbon
@@ -55,6 +55,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_memaccess_category.carbon b/toolchain/check/testdata/class/fail_memaccess_category.carbon
index cfd19e49e362..26897275f2e2 100644
--- a/toolchain/check/testdata/class/fail_memaccess_category.carbon
+++ b/toolchain/check/testdata/class/fail_memaccess_category.carbon
@@ -66,6 +66,7 @@ fn F(s: {.a: A}, b: B) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_member_of_let.carbon b/toolchain/check/testdata/class/fail_member_of_let.carbon
index 3c76f31becdb..125c5bc30991 100644
--- a/toolchain/check/testdata/class/fail_member_of_let.carbon
+++ b/toolchain/check/testdata/class/fail_member_of_let.carbon
@@ -48,6 +48,7 @@ fn T.F() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_method.carbon b/toolchain/check/testdata/class/fail_method.carbon
index 329b725502b4..5979171aa37b 100644
--- a/toolchain/check/testdata/class/fail_method.carbon
+++ b/toolchain/check/testdata/class/fail_method.carbon
@@ -69,6 +69,7 @@ fn F(c: Class) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_method_modifiers.carbon b/toolchain/check/testdata/class/fail_method_modifiers.carbon
index c30bb644a7fe..84d7ce2184ac 100644
--- a/toolchain/check/testdata/class/fail_method_modifiers.carbon
+++ b/toolchain/check/testdata/class/fail_method_modifiers.carbon
@@ -83,6 +83,7 @@ base class BaseClass {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_method_redefinition.carbon b/toolchain/check/testdata/class/fail_method_redefinition.carbon
index d5bc9770d394..e451b80810e3 100644
--- a/toolchain/check/testdata/class/fail_method_redefinition.carbon
+++ b/toolchain/check/testdata/class/fail_method_redefinition.carbon
@@ -37,6 +37,7 @@ class Class {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_modifiers.carbon b/toolchain/check/testdata/class/fail_modifiers.carbon
index 1414099a8784..b47a68a9a7ca 100644
--- a/toolchain/check/testdata/class/fail_modifiers.carbon
+++ b/toolchain/check/testdata/class/fail_modifiers.carbon
@@ -127,6 +127,7 @@ fn AbstractWithDefinition.G() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_out_of_line_decl.carbon b/toolchain/check/testdata/class/fail_out_of_line_decl.carbon
index 80e64a4cd232..63304989e206 100644
--- a/toolchain/check/testdata/class/fail_out_of_line_decl.carbon
+++ b/toolchain/check/testdata/class/fail_out_of_line_decl.carbon
@@ -33,6 +33,7 @@ fn C.F() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_redeclaration_scope.carbon b/toolchain/check/testdata/class/fail_redeclaration_scope.carbon
index eefc699a9ddd..f51e532b1cc1 100644
--- a/toolchain/check/testdata/class/fail_redeclaration_scope.carbon
+++ b/toolchain/check/testdata/class/fail_redeclaration_scope.carbon
@@ -46,6 +46,7 @@ class Y {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_redefinition.carbon b/toolchain/check/testdata/class/fail_redefinition.carbon
index 29647e15b2e0..cf342bc85063 100644
--- a/toolchain/check/testdata/class/fail_redefinition.carbon
+++ b/toolchain/check/testdata/class/fail_redefinition.carbon
@@ -73,6 +73,7 @@ fn Class.I() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_scope.carbon b/toolchain/check/testdata/class/fail_scope.carbon
index 2517ca2ad960..d20a9513230c 100644
--- a/toolchain/check/testdata/class/fail_scope.carbon
+++ b/toolchain/check/testdata/class/fail_scope.carbon
@@ -45,6 +45,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_self.carbon b/toolchain/check/testdata/class/fail_self.carbon
index 9c1c1000ca5b..56948c8d2ae7 100644
--- a/toolchain/check/testdata/class/fail_self.carbon
+++ b/toolchain/check/testdata/class/fail_self.carbon
@@ -99,6 +99,7 @@ fn CallWrongSelf(ws: WrongSelf) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_self_param.carbon b/toolchain/check/testdata/class/fail_self_param.carbon
index df630f757459..cf71151b8ad5 100644
--- a/toolchain/check/testdata/class/fail_self_param.carbon
+++ b/toolchain/check/testdata/class/fail_self_param.carbon
@@ -35,6 +35,7 @@ var v: C(0);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_unbound_field.carbon b/toolchain/check/testdata/class/fail_unbound_field.carbon
index 55766c6ee464..c606f75feefd 100644
--- a/toolchain/check/testdata/class/fail_unbound_field.carbon
+++ b/toolchain/check/testdata/class/fail_unbound_field.carbon
@@ -51,6 +51,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/fail_unknown_member.carbon b/toolchain/check/testdata/class/fail_unknown_member.carbon
index 349ed34d79da..ef78df85b2ef 100644
--- a/toolchain/check/testdata/class/fail_unknown_member.carbon
+++ b/toolchain/check/testdata/class/fail_unknown_member.carbon
@@ -43,6 +43,7 @@ fn G(c: Class) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/field_access.carbon b/toolchain/check/testdata/class/field_access.carbon
index c41db1e32565..64f6589e1da4 100644
--- a/toolchain/check/testdata/class/field_access.carbon
+++ b/toolchain/check/testdata/class/field_access.carbon
@@ -46,6 +46,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/field_access_in_value.carbon b/toolchain/check/testdata/class/field_access_in_value.carbon
index 11a1667cbdcf..13b0306f1c59 100644
--- a/toolchain/check/testdata/class/field_access_in_value.carbon
+++ b/toolchain/check/testdata/class/field_access_in_value.carbon
@@ -47,6 +47,7 @@ fn Test() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/forward_declared.carbon b/toolchain/check/testdata/class/forward_declared.carbon
index c1be5a4c5dc2..44707d6b367f 100644
--- a/toolchain/check/testdata/class/forward_declared.carbon
+++ b/toolchain/check/testdata/class/forward_declared.carbon
@@ -29,6 +29,7 @@ fn F(p: Class*) -> Class* { return p; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic.carbon b/toolchain/check/testdata/class/generic.carbon
index 792313b41dd7..6d516446990b 100644
--- a/toolchain/check/testdata/class/generic.carbon
+++ b/toolchain/check/testdata/class/generic.carbon
@@ -26,6 +26,7 @@ class C[]();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/basic.carbon b/toolchain/check/testdata/class/generic/basic.carbon
index 5ac27cbd7b80..c6d6e4c1e400 100644
--- a/toolchain/check/testdata/class/generic/basic.carbon
+++ b/toolchain/check/testdata/class/generic/basic.carbon
@@ -55,6 +55,7 @@ class Declaration(T:! type);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/call.carbon b/toolchain/check/testdata/class/generic/call.carbon
index e2777b7147f7..15584e2fbea3 100644
--- a/toolchain/check/testdata/class/generic/call.carbon
+++ b/toolchain/check/testdata/class/generic/call.carbon
@@ -116,6 +116,7 @@ class Outer(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -232,6 +233,7 @@ class Outer(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -322,6 +324,7 @@ class Outer(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -431,6 +434,7 @@ class Outer(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -616,6 +620,7 @@ class Outer(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/field.carbon b/toolchain/check/testdata/class/generic/field.carbon
index f30d3075b70e..967127df62d8 100644
--- a/toolchain/check/testdata/class/generic/field.carbon
+++ b/toolchain/check/testdata/class/generic/field.carbon
@@ -68,6 +68,7 @@ fn H(U:! type, c: Class(U)) -> U {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/import.carbon b/toolchain/check/testdata/class/generic/import.carbon
index ef765194ccea..de200d88205d 100644
--- a/toolchain/check/testdata/class/generic/import.carbon
+++ b/toolchain/check/testdata/class/generic/import.carbon
@@ -118,6 +118,7 @@ class Class(U:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -289,6 +290,7 @@ class Class(U:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -468,6 +470,7 @@ class Class(U:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -676,6 +679,7 @@ class Class(U:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -883,6 +887,7 @@ class Class(U:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/init.carbon b/toolchain/check/testdata/class/generic/init.carbon
index 669233d1ff40..383b183e86bf 100644
--- a/toolchain/check/testdata/class/generic/init.carbon
+++ b/toolchain/check/testdata/class/generic/init.carbon
@@ -77,6 +77,7 @@ fn InitFromAdaptedSpecific(x: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -278,6 +279,7 @@ fn InitFromAdaptedSpecific(x: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/member_access.carbon b/toolchain/check/testdata/class/generic/member_access.carbon
index 7fa848f5c447..538def6c2b60 100644
--- a/toolchain/check/testdata/class/generic/member_access.carbon
+++ b/toolchain/check/testdata/class/generic/member_access.carbon
@@ -96,6 +96,7 @@ fn StaticMemberFunctionCall(T:! type) -> Class(T) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -436,6 +437,7 @@ fn StaticMemberFunctionCall(T:! type) -> Class(T) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/member_inline.carbon b/toolchain/check/testdata/class/generic/member_inline.carbon
index db64eb057fc7..246498b64811 100644
--- a/toolchain/check/testdata/class/generic/member_inline.carbon
+++ b/toolchain/check/testdata/class/generic/member_inline.carbon
@@ -64,6 +64,7 @@ class C(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -226,6 +227,7 @@ class C(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/member_out_of_line.carbon b/toolchain/check/testdata/class/generic/member_out_of_line.carbon
index cf5a89321a7e..9dd617e13141 100644
--- a/toolchain/check/testdata/class/generic/member_out_of_line.carbon
+++ b/toolchain/check/testdata/class/generic/member_out_of_line.carbon
@@ -133,6 +133,7 @@ fn Generic(T:! ()).WrongType() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -332,6 +333,7 @@ fn Generic(T:! ()).WrongType() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -506,6 +508,7 @@ fn Generic(T:! ()).WrongType() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -577,6 +580,7 @@ fn Generic(T:! ()).WrongType() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -666,6 +670,7 @@ fn Generic(T:! ()).WrongType() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -775,6 +780,7 @@ fn Generic(T:! ()).WrongType() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/method_deduce.carbon b/toolchain/check/testdata/class/generic/method_deduce.carbon
index d588aa1fcf67..40a3e1ddf912 100644
--- a/toolchain/check/testdata/class/generic/method_deduce.carbon
+++ b/toolchain/check/testdata/class/generic/method_deduce.carbon
@@ -74,6 +74,7 @@ fn CallGenericMethodWithNonDeducedParam(c: Class(A)) -> (A, B) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/redeclare.carbon b/toolchain/check/testdata/class/generic/redeclare.carbon
index f4c4453d28b1..743394f094b0 100644
--- a/toolchain/check/testdata/class/generic/redeclare.carbon
+++ b/toolchain/check/testdata/class/generic/redeclare.carbon
@@ -107,6 +107,7 @@ class E(U:! type) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -175,6 +176,7 @@ class E(U:! type) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -248,6 +250,7 @@ class E(U:! type) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -351,6 +354,7 @@ class E(U:! type) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -452,6 +456,7 @@ class E(U:! type) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -542,6 +547,7 @@ class E(U:! type) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic/self.carbon b/toolchain/check/testdata/class/generic/self.carbon
index 55f22f60505e..eddfa7cd2c3b 100644
--- a/toolchain/check/testdata/class/generic/self.carbon
+++ b/toolchain/check/testdata/class/generic/self.carbon
@@ -49,6 +49,7 @@ class Class(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/generic_method.carbon b/toolchain/check/testdata/class/generic_method.carbon
index dd954971fa2e..6624c1f1a4a6 100644
--- a/toolchain/check/testdata/class/generic_method.carbon
+++ b/toolchain/check/testdata/class/generic_method.carbon
@@ -40,6 +40,7 @@ fn Class(T:! type).F[self: Self](n: T) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/import.carbon b/toolchain/check/testdata/class/import.carbon
index e875fb152e56..6d40f5fb3733 100644
--- a/toolchain/check/testdata/class/import.carbon
+++ b/toolchain/check/testdata/class/import.carbon
@@ -79,6 +79,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -198,6 +199,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/import_base.carbon b/toolchain/check/testdata/class/import_base.carbon
index af14c23824d0..caae774a0706 100644
--- a/toolchain/check/testdata/class/import_base.carbon
+++ b/toolchain/check/testdata/class/import_base.carbon
@@ -65,6 +65,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -171,6 +172,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/import_forward_decl.carbon b/toolchain/check/testdata/class/import_forward_decl.carbon
index a504c375e1f1..aa8cb938766e 100644
--- a/toolchain/check/testdata/class/import_forward_decl.carbon
+++ b/toolchain/check/testdata/class/import_forward_decl.carbon
@@ -34,6 +34,7 @@ class ForwardDecl {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -67,6 +68,7 @@ class ForwardDecl {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/import_indirect.carbon b/toolchain/check/testdata/class/import_indirect.carbon
index d6b82dadf8a7..fbda4cc0f140 100644
--- a/toolchain/check/testdata/class/import_indirect.carbon
+++ b/toolchain/check/testdata/class/import_indirect.carbon
@@ -115,6 +115,7 @@ var ptr: E* = &val;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -157,6 +158,7 @@ var ptr: E* = &val;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -222,6 +224,7 @@ var ptr: E* = &val;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -290,6 +293,7 @@ var ptr: E* = &val;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -358,6 +362,7 @@ var ptr: E* = &val;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -428,6 +433,7 @@ var ptr: E* = &val;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -500,6 +506,7 @@ var ptr: E* = &val;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/import_member_cycle.carbon b/toolchain/check/testdata/class/import_member_cycle.carbon
index 16352e6a924f..7c6a2b2d25be 100644
--- a/toolchain/check/testdata/class/import_member_cycle.carbon
+++ b/toolchain/check/testdata/class/import_member_cycle.carbon
@@ -43,6 +43,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -89,6 +90,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/import_struct_cyle.carbon b/toolchain/check/testdata/class/import_struct_cyle.carbon
index 15e50b42aa37..cab6eaa127a0 100644
--- a/toolchain/check/testdata/class/import_struct_cyle.carbon
+++ b/toolchain/check/testdata/class/import_struct_cyle.carbon
@@ -49,6 +49,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -107,6 +108,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/inheritance_access.carbon b/toolchain/check/testdata/class/inheritance_access.carbon
index 39fd189139c7..de692232331a 100644
--- a/toolchain/check/testdata/class/inheritance_access.carbon
+++ b/toolchain/check/testdata/class/inheritance_access.carbon
@@ -258,6 +258,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -390,6 +391,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -516,6 +518,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -645,6 +648,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -732,6 +736,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -792,6 +797,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -858,6 +864,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -936,6 +943,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1020,6 +1028,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1159,6 +1168,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1248,6 +1258,7 @@ class B {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/init.carbon b/toolchain/check/testdata/class/init.carbon
index 2c2b56683d2c..98fa67abe3b3 100644
--- a/toolchain/check/testdata/class/init.carbon
+++ b/toolchain/check/testdata/class/init.carbon
@@ -49,6 +49,7 @@ fn MakeReorder(n: i32, next: Class*) -> Class {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/init_adapt.carbon b/toolchain/check/testdata/class/init_adapt.carbon
index 504e05bac712..4075b9a43338 100644
--- a/toolchain/check/testdata/class/init_adapt.carbon
+++ b/toolchain/check/testdata/class/init_adapt.carbon
@@ -121,6 +121,7 @@ var e: C = MakeAdaptC();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -298,6 +299,7 @@ var e: C = MakeAdaptC();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/init_as.carbon b/toolchain/check/testdata/class/init_as.carbon
index eba1fb2da604..0feeb6d9bf4a 100644
--- a/toolchain/check/testdata/class/init_as.carbon
+++ b/toolchain/check/testdata/class/init_as.carbon
@@ -43,6 +43,7 @@ fn F() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/init_nested.carbon b/toolchain/check/testdata/class/init_nested.carbon
index 9667099708fd..36fc6c96bbd1 100644
--- a/toolchain/check/testdata/class/init_nested.carbon
+++ b/toolchain/check/testdata/class/init_nested.carbon
@@ -56,6 +56,7 @@ fn MakeOuter() -> Outer {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/method.carbon b/toolchain/check/testdata/class/method.carbon
index acba24d5e28e..982ec49496f3 100644
--- a/toolchain/check/testdata/class/method.carbon
+++ b/toolchain/check/testdata/class/method.carbon
@@ -104,6 +104,7 @@ fn CallGOnInitializingExpr() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/nested.carbon b/toolchain/check/testdata/class/nested.carbon
index 678daddbc48a..de1d696bbfbe 100644
--- a/toolchain/check/testdata/class/nested.carbon
+++ b/toolchain/check/testdata/class/nested.carbon
@@ -84,6 +84,7 @@ fn F(a: Outer*) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/nested_name.carbon b/toolchain/check/testdata/class/nested_name.carbon
index d6fae7db57f8..1af2f19b4237 100644
--- a/toolchain/check/testdata/class/nested_name.carbon
+++ b/toolchain/check/testdata/class/nested_name.carbon
@@ -51,6 +51,7 @@ fn G(o: Outer) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/raw_self.carbon b/toolchain/check/testdata/class/raw_self.carbon
index 67ba33807f7f..cb077ac47002 100644
--- a/toolchain/check/testdata/class/raw_self.carbon
+++ b/toolchain/check/testdata/class/raw_self.carbon
@@ -51,6 +51,7 @@ fn Class.G[self: Self](r#self: i32) -> (i32, i32) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/raw_self_type.carbon b/toolchain/check/testdata/class/raw_self_type.carbon
index 5575ccbb58e6..f1472d377b30 100644
--- a/toolchain/check/testdata/class/raw_self_type.carbon
+++ b/toolchain/check/testdata/class/raw_self_type.carbon
@@ -47,6 +47,7 @@ fn MemberNamedSelf.F(x: Self, y: r#Self) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/redeclaration.carbon b/toolchain/check/testdata/class/redeclaration.carbon
index d469e66bf773..88884cecab11 100644
--- a/toolchain/check/testdata/class/redeclaration.carbon
+++ b/toolchain/check/testdata/class/redeclaration.carbon
@@ -38,6 +38,7 @@ fn Class.F[self: Self](b: bool) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/redeclaration_introducer.carbon b/toolchain/check/testdata/class/redeclaration_introducer.carbon
index 614b6ce466c0..bf36b192702a 100644
--- a/toolchain/check/testdata/class/redeclaration_introducer.carbon
+++ b/toolchain/check/testdata/class/redeclaration_introducer.carbon
@@ -33,6 +33,7 @@ abstract class C {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/reenter_scope.carbon b/toolchain/check/testdata/class/reenter_scope.carbon
index 82449eb9bcd1..1cf1af8045a9 100644
--- a/toolchain/check/testdata/class/reenter_scope.carbon
+++ b/toolchain/check/testdata/class/reenter_scope.carbon
@@ -42,6 +42,7 @@ fn Class.F() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/reorder.carbon b/toolchain/check/testdata/class/reorder.carbon
index 16c86a1496c5..a01b36f4f57e 100644
--- a/toolchain/check/testdata/class/reorder.carbon
+++ b/toolchain/check/testdata/class/reorder.carbon
@@ -43,6 +43,7 @@ class Class {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/reorder_qualified.carbon b/toolchain/check/testdata/class/reorder_qualified.carbon
index 0e26ae6ae8b5..5ea5420fca13 100644
--- a/toolchain/check/testdata/class/reorder_qualified.carbon
+++ b/toolchain/check/testdata/class/reorder_qualified.carbon
@@ -100,6 +100,7 @@ class A {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/scope.carbon b/toolchain/check/testdata/class/scope.carbon
index a7387df5f979..183ee7763dc4 100644
--- a/toolchain/check/testdata/class/scope.carbon
+++ b/toolchain/check/testdata/class/scope.carbon
@@ -57,6 +57,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/self.carbon b/toolchain/check/testdata/class/self.carbon
index 5981b519acab..709fb578cdc2 100644
--- a/toolchain/check/testdata/class/self.carbon
+++ b/toolchain/check/testdata/class/self.carbon
@@ -74,6 +74,7 @@ class Class {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -225,6 +226,7 @@ class Class {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/self_conversion.carbon b/toolchain/check/testdata/class/self_conversion.carbon
index 59345dfc76ec..dde6def3ffd0 100644
--- a/toolchain/check/testdata/class/self_conversion.carbon
+++ b/toolchain/check/testdata/class/self_conversion.carbon
@@ -68,6 +68,7 @@ fn Call(p: Derived*) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/self_type.carbon b/toolchain/check/testdata/class/self_type.carbon
index f3edc1d3d369..bd0c8c77cec0 100644
--- a/toolchain/check/testdata/class/self_type.carbon
+++ b/toolchain/check/testdata/class/self_type.carbon
@@ -48,6 +48,7 @@ fn Class.F[self: Self]() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/static_method.carbon b/toolchain/check/testdata/class/static_method.carbon
index 9d3d9977cb72..971da3cb8cb1 100644
--- a/toolchain/check/testdata/class/static_method.carbon
+++ b/toolchain/check/testdata/class/static_method.carbon
@@ -41,6 +41,7 @@ fn Run() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/syntactic_merge_literal.carbon b/toolchain/check/testdata/class/syntactic_merge_literal.carbon
index 65224371225e..d259ccf913ee 100644
--- a/toolchain/check/testdata/class/syntactic_merge_literal.carbon
+++ b/toolchain/check/testdata/class/syntactic_merge_literal.carbon
@@ -59,6 +59,7 @@ class D(b:! C(1_000)) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -184,6 +185,7 @@ class D(b:! C(1_000)) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/todo_access_modifiers.carbon b/toolchain/check/testdata/class/todo_access_modifiers.carbon
index dc47efd098f7..45da43f9443c 100644
--- a/toolchain/check/testdata/class/todo_access_modifiers.carbon
+++ b/toolchain/check/testdata/class/todo_access_modifiers.carbon
@@ -43,6 +43,7 @@ class Access {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/class/virtual_modifiers.carbon b/toolchain/check/testdata/class/virtual_modifiers.carbon
index 90bb99063f73..3380e7dbb4c6 100644
--- a/toolchain/check/testdata/class/virtual_modifiers.carbon
+++ b/toolchain/check/testdata/class/virtual_modifiers.carbon
@@ -79,6 +79,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -154,6 +155,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -223,6 +225,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/const/basic.carbon b/toolchain/check/testdata/const/basic.carbon
index 68f93c10880d..77482061c0b4 100644
--- a/toolchain/check/testdata/const/basic.carbon
+++ b/toolchain/check/testdata/const/basic.carbon
@@ -41,6 +41,7 @@ fn B(p: const (i32*)) -> const (i32*) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/const/collapse.carbon b/toolchain/check/testdata/const/collapse.carbon
index 322446ae66d8..62a672ad8373 100644
--- a/toolchain/check/testdata/const/collapse.carbon
+++ b/toolchain/check/testdata/const/collapse.carbon
@@ -37,6 +37,7 @@ fn F(p: const i32**) -> const (const i32)** {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/const/fail_collapse.carbon b/toolchain/check/testdata/const/fail_collapse.carbon
index 9b875ac62277..54ad49593f63 100644
--- a/toolchain/check/testdata/const/fail_collapse.carbon
+++ b/toolchain/check/testdata/const/fail_collapse.carbon
@@ -63,6 +63,7 @@ fn G(p: const (const i32)**) -> i32** {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/const/import.carbon b/toolchain/check/testdata/const/import.carbon
index efae6dc201b1..3a31b08700ac 100644
--- a/toolchain/check/testdata/const/import.carbon
+++ b/toolchain/check/testdata/const/import.carbon
@@ -46,6 +46,7 @@ var a_ptr: const i32* = a_ptr_ref;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -123,6 +124,7 @@ var a_ptr: const i32* = a_ptr_ref;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/deduce/array.carbon b/toolchain/check/testdata/deduce/array.carbon
index 7c57f88b5db1..f6dac18a9066 100644
--- a/toolchain/check/testdata/deduce/array.carbon
+++ b/toolchain/check/testdata/deduce/array.carbon
@@ -132,6 +132,7 @@ fn G() -> C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -285,6 +286,7 @@ fn G() -> C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -430,6 +432,7 @@ fn G() -> C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -593,6 +596,7 @@ fn G() -> C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -818,6 +822,7 @@ fn G() -> C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/deduce/generic_type.carbon b/toolchain/check/testdata/deduce/generic_type.carbon
index 14aa1b2ab8a4..2a68bf5055c1 100644
--- a/toolchain/check/testdata/deduce/generic_type.carbon
+++ b/toolchain/check/testdata/deduce/generic_type.carbon
@@ -95,6 +95,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -278,6 +279,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -476,6 +478,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -775,6 +778,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/deduce/int_float.carbon b/toolchain/check/testdata/deduce/int_float.carbon
index 5217f8c97719..6f874a37b662 100644
--- a/toolchain/check/testdata/deduce/int_float.carbon
+++ b/toolchain/check/testdata/deduce/int_float.carbon
@@ -65,6 +65,7 @@ fn G(a: f64) -> Core.BigInt() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -202,6 +203,7 @@ fn G(a: f64) -> Core.BigInt() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/deduce/tuple.carbon b/toolchain/check/testdata/deduce/tuple.carbon
index 519c57a53a36..9a03242d4c01 100644
--- a/toolchain/check/testdata/deduce/tuple.carbon
+++ b/toolchain/check/testdata/deduce/tuple.carbon
@@ -86,6 +86,7 @@ fn G(pair: (C, D)) -> D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -263,6 +264,7 @@ fn G(pair: (C, D)) -> D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -468,6 +470,7 @@ fn G(pair: (C, D)) -> D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/deduce/type_operator.carbon b/toolchain/check/testdata/deduce/type_operator.carbon
index b28227aa4b29..0fd3750da502 100644
--- a/toolchain/check/testdata/deduce/type_operator.carbon
+++ b/toolchain/check/testdata/deduce/type_operator.carbon
@@ -89,6 +89,7 @@ fn G(p: C*) -> const C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -228,6 +229,7 @@ fn G(p: C*) -> const C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -372,6 +374,7 @@ fn G(p: C*) -> const C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -512,6 +515,7 @@ fn G(p: C*) -> const C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/eval/aggregate.carbon b/toolchain/check/testdata/eval/aggregate.carbon
index c5b144e8c2bf..1e91aa82492b 100644
--- a/toolchain/check/testdata/eval/aggregate.carbon
+++ b/toolchain/check/testdata/eval/aggregate.carbon
@@ -60,6 +60,7 @@ var struct_access: [i32; 1] = (0,) as [i32; {.a = 3, .b = 1}.b];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/eval/fail_aggregate.carbon b/toolchain/check/testdata/eval/fail_aggregate.carbon
index 09a2852bc315..e9986889bac2 100644
--- a/toolchain/check/testdata/eval/fail_aggregate.carbon
+++ b/toolchain/check/testdata/eval/fail_aggregate.carbon
@@ -46,6 +46,7 @@ var array_index: [i32; 1] = (0,) as [i32; ((5, 7, 1, 9) as [i32; 4])[2]];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/eval/fail_symbolic.carbon b/toolchain/check/testdata/eval/fail_symbolic.carbon
index 6bc70fef8c79..60b8625fb22d 100644
--- a/toolchain/check/testdata/eval/fail_symbolic.carbon
+++ b/toolchain/check/testdata/eval/fail_symbolic.carbon
@@ -36,6 +36,7 @@ fn G(N:! i32) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/eval/symbolic.carbon b/toolchain/check/testdata/eval/symbolic.carbon
index 20d2227ddeae..7cf99395b502 100644
--- a/toolchain/check/testdata/eval/symbolic.carbon
+++ b/toolchain/check/testdata/eval/symbolic.carbon
@@ -42,6 +42,7 @@ fn F(T:! type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/expr_category/in_place_tuple_init.carbon b/toolchain/check/testdata/expr_category/in_place_tuple_init.carbon
index 7dd00f3f4eb9..779f900bade6 100644
--- a/toolchain/check/testdata/expr_category/in_place_tuple_init.carbon
+++ b/toolchain/check/testdata/expr_category/in_place_tuple_init.carbon
@@ -46,6 +46,7 @@ fn H() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/builtin/call.carbon b/toolchain/check/testdata/function/builtin/call.carbon
index dd3923cb937d..56f952b2d201 100644
--- a/toolchain/check/testdata/function/builtin/call.carbon
+++ b/toolchain/check/testdata/function/builtin/call.carbon
@@ -35,6 +35,7 @@ var arr: [i32; Add(1, 2)];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/builtin/definition.carbon b/toolchain/check/testdata/function/builtin/definition.carbon
index a0c5196e408c..e4b4282824ac 100644
--- a/toolchain/check/testdata/function/builtin/definition.carbon
+++ b/toolchain/check/testdata/function/builtin/definition.carbon
@@ -28,6 +28,7 @@ fn Add(a: i32, b: i32) -> i32 = "int.sadd";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/builtin/fail_redefined.carbon b/toolchain/check/testdata/function/builtin/fail_redefined.carbon
index 54e0b4a90ae7..64056696e36e 100644
--- a/toolchain/check/testdata/function/builtin/fail_redefined.carbon
+++ b/toolchain/check/testdata/function/builtin/fail_redefined.carbon
@@ -59,6 +59,7 @@ fn C(n: i32, m: i32) -> i32 = "int.sadd";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/builtin/fail_unknown.carbon b/toolchain/check/testdata/function/builtin/fail_unknown.carbon
index 8d588dfe61a1..042c3c0471d1 100644
--- a/toolchain/check/testdata/function/builtin/fail_unknown.carbon
+++ b/toolchain/check/testdata/function/builtin/fail_unknown.carbon
@@ -28,6 +28,7 @@ fn UnknownBuiltin() = "unknown.builtin.name";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/builtin/method.carbon b/toolchain/check/testdata/function/builtin/method.carbon
index c82caf073b57..47f916c908af 100644
--- a/toolchain/check/testdata/function/builtin/method.carbon
+++ b/toolchain/check/testdata/function/builtin/method.carbon
@@ -49,6 +49,7 @@ var arr: [i32; 1.(I.F)(2)];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/fail_not_callable.carbon b/toolchain/check/testdata/function/call/fail_not_callable.carbon
index 53bad7b4a495..f97f52d3bb8e 100644
--- a/toolchain/check/testdata/function/call/fail_not_callable.carbon
+++ b/toolchain/check/testdata/function/call/fail_not_callable.carbon
@@ -35,6 +35,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/fail_param_count.carbon b/toolchain/check/testdata/function/call/fail_param_count.carbon
index 4c3aa4679272..2972c5a15080 100644
--- a/toolchain/check/testdata/function/call/fail_param_count.carbon
+++ b/toolchain/check/testdata/function/call/fail_param_count.carbon
@@ -90,6 +90,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/fail_param_type.carbon b/toolchain/check/testdata/function/call/fail_param_type.carbon
index ab63e351dfbe..bb635ee95f2f 100644
--- a/toolchain/check/testdata/function/call/fail_param_type.carbon
+++ b/toolchain/check/testdata/function/call/fail_param_type.carbon
@@ -62,6 +62,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/fail_return_type_mismatch.carbon b/toolchain/check/testdata/function/call/fail_return_type_mismatch.carbon
index 87e6ab101ac8..c2307e3ff108 100644
--- a/toolchain/check/testdata/function/call/fail_return_type_mismatch.carbon
+++ b/toolchain/check/testdata/function/call/fail_return_type_mismatch.carbon
@@ -63,6 +63,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/i32.carbon b/toolchain/check/testdata/function/call/i32.carbon
index c38b3b94a7d3..9b85af3779dc 100644
--- a/toolchain/check/testdata/function/call/i32.carbon
+++ b/toolchain/check/testdata/function/call/i32.carbon
@@ -37,6 +37,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/more_param_ir.carbon b/toolchain/check/testdata/function/call/more_param_ir.carbon
index d83974e86fbc..dbd329c97249 100644
--- a/toolchain/check/testdata/function/call/more_param_ir.carbon
+++ b/toolchain/check/testdata/function/call/more_param_ir.carbon
@@ -42,6 +42,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/params_one.carbon b/toolchain/check/testdata/function/call/params_one.carbon
index 19f4dd694ee1..8cf53d401aef 100644
--- a/toolchain/check/testdata/function/call/params_one.carbon
+++ b/toolchain/check/testdata/function/call/params_one.carbon
@@ -35,6 +35,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/params_one_comma.carbon b/toolchain/check/testdata/function/call/params_one_comma.carbon
index 487df15148ee..479d0add0f22 100644
--- a/toolchain/check/testdata/function/call/params_one_comma.carbon
+++ b/toolchain/check/testdata/function/call/params_one_comma.carbon
@@ -36,6 +36,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/params_two.carbon b/toolchain/check/testdata/function/call/params_two.carbon
index f931494eb24e..4e924ea6ef96 100644
--- a/toolchain/check/testdata/function/call/params_two.carbon
+++ b/toolchain/check/testdata/function/call/params_two.carbon
@@ -36,6 +36,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/call/params_two_comma.carbon b/toolchain/check/testdata/function/call/params_two_comma.carbon
index 346746298347..957f1a233afa 100644
--- a/toolchain/check/testdata/function/call/params_two_comma.carbon
+++ b/toolchain/check/testdata/function/call/params_two_comma.carbon
@@ -37,6 +37,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/declaration/fail_param_in_type.carbon b/toolchain/check/testdata/function/declaration/fail_param_in_type.carbon
index d844410e12a7..18827517ef1d 100644
--- a/toolchain/check/testdata/function/declaration/fail_param_in_type.carbon
+++ b/toolchain/check/testdata/function/declaration/fail_param_in_type.carbon
@@ -31,6 +31,7 @@ fn F(n: i32, a: [i32; n]*);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/declaration/fail_param_redecl.carbon b/toolchain/check/testdata/function/declaration/fail_param_redecl.carbon
index a6323d43060c..8f8fb9cf0be2 100644
--- a/toolchain/check/testdata/function/declaration/fail_param_redecl.carbon
+++ b/toolchain/check/testdata/function/declaration/fail_param_redecl.carbon
@@ -34,6 +34,7 @@ fn F(n: i32, n: i32);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/declaration/import.carbon b/toolchain/check/testdata/function/declaration/import.carbon
index 9a85d3668e14..b3c908ca9dcd 100644
--- a/toolchain/check/testdata/function/declaration/import.carbon
+++ b/toolchain/check/testdata/function/declaration/import.carbon
@@ -284,6 +284,7 @@ import library "extern_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -387,6 +388,7 @@ import library "extern_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -500,6 +502,7 @@ import library "extern_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -626,6 +629,7 @@ import library "extern_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -782,6 +786,7 @@ import library "extern_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -942,6 +947,7 @@ import library "extern_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1072,6 +1078,7 @@ import library "extern_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1176,6 +1183,7 @@ import library "extern_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1213,6 +1221,7 @@ import library "extern_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/declaration/param_same_name.carbon b/toolchain/check/testdata/function/declaration/param_same_name.carbon
index bf574645b96d..91c07d979905 100644
--- a/toolchain/check/testdata/function/declaration/param_same_name.carbon
+++ b/toolchain/check/testdata/function/declaration/param_same_name.carbon
@@ -32,6 +32,7 @@ fn G(a: i32);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/definition/import.carbon b/toolchain/check/testdata/function/definition/import.carbon
index c04075c372a4..5ccaf4dd944d 100644
--- a/toolchain/check/testdata/function/definition/import.carbon
+++ b/toolchain/check/testdata/function/definition/import.carbon
@@ -137,6 +137,7 @@ fn D() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -235,6 +236,7 @@ fn D() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -282,6 +284,7 @@ fn D() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -370,6 +373,7 @@ fn D() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -427,6 +431,7 @@ fn D() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -468,6 +473,7 @@ fn D() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/definition/import_access.carbon b/toolchain/check/testdata/function/definition/import_access.carbon
index 96d945a97979..f594c80877a1 100644
--- a/toolchain/check/testdata/function/definition/import_access.carbon
+++ b/toolchain/check/testdata/function/definition/import_access.carbon
@@ -150,6 +150,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -185,6 +186,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -221,6 +223,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -254,6 +257,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -298,6 +302,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -337,6 +342,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -384,6 +390,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -428,6 +435,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -467,6 +475,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -514,6 +523,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -562,6 +572,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -601,6 +612,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -647,6 +659,7 @@ private fn Redecl() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/definition/params_one.carbon b/toolchain/check/testdata/function/definition/params_one.carbon
index 3e46d3eeee07..da520fcb3498 100644
--- a/toolchain/check/testdata/function/definition/params_one.carbon
+++ b/toolchain/check/testdata/function/definition/params_one.carbon
@@ -28,6 +28,7 @@ fn Foo(a: i32) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/definition/params_one_comma.carbon b/toolchain/check/testdata/function/definition/params_one_comma.carbon
index 829d2c37fa0e..3374466939ed 100644
--- a/toolchain/check/testdata/function/definition/params_one_comma.carbon
+++ b/toolchain/check/testdata/function/definition/params_one_comma.carbon
@@ -28,6 +28,7 @@ fn Foo(a: i32,) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/definition/params_two.carbon b/toolchain/check/testdata/function/definition/params_two.carbon
index b276cbb40cc7..9d2cf2fbdd53 100644
--- a/toolchain/check/testdata/function/definition/params_two.carbon
+++ b/toolchain/check/testdata/function/definition/params_two.carbon
@@ -28,6 +28,7 @@ fn Foo(a: i32, b: i32) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/definition/params_two_comma.carbon b/toolchain/check/testdata/function/definition/params_two_comma.carbon
index ec0624124092..a36198bb5293 100644
--- a/toolchain/check/testdata/function/definition/params_two_comma.carbon
+++ b/toolchain/check/testdata/function/definition/params_two_comma.carbon
@@ -28,6 +28,7 @@ fn Foo(a: i32, b: i32,) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/generic/deduce.carbon b/toolchain/check/testdata/function/generic/deduce.carbon
index 1027ae7062fd..f9cecf7a0681 100644
--- a/toolchain/check/testdata/function/generic/deduce.carbon
+++ b/toolchain/check/testdata/function/generic/deduce.carbon
@@ -161,6 +161,7 @@ fn CallImplicitNotDeducible() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -343,6 +344,7 @@ fn CallImplicitNotDeducible() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -485,6 +487,7 @@ fn CallImplicitNotDeducible() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -624,6 +627,7 @@ fn CallImplicitNotDeducible() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -764,6 +768,7 @@ fn CallImplicitNotDeducible() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -867,6 +872,7 @@ fn CallImplicitNotDeducible() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -952,6 +958,7 @@ fn CallImplicitNotDeducible() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1034,6 +1041,7 @@ fn CallImplicitNotDeducible() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/generic/fail_todo_param_in_type.carbon b/toolchain/check/testdata/function/generic/fail_todo_param_in_type.carbon
index 215e028b9bb6..235ec387ed38 100644
--- a/toolchain/check/testdata/function/generic/fail_todo_param_in_type.carbon
+++ b/toolchain/check/testdata/function/generic/fail_todo_param_in_type.carbon
@@ -33,6 +33,7 @@ fn F(N:! i32, a: [i32; N]*);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/generic/redeclare.carbon b/toolchain/check/testdata/function/generic/redeclare.carbon
index 15b0cd172736..b758cdb8c524 100644
--- a/toolchain/check/testdata/function/generic/redeclare.carbon
+++ b/toolchain/check/testdata/function/generic/redeclare.carbon
@@ -109,6 +109,7 @@ fn F(U:! type, T:! type) -> U* {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -209,6 +210,7 @@ fn F(U:! type, T:! type) -> U* {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -327,6 +329,7 @@ fn F(U:! type, T:! type) -> U* {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -445,6 +448,7 @@ fn F(U:! type, T:! type) -> U* {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/generic/resolve_used.carbon b/toolchain/check/testdata/function/generic/resolve_used.carbon
index 836e796646e8..431e5e9467e7 100644
--- a/toolchain/check/testdata/function/generic/resolve_used.carbon
+++ b/toolchain/check/testdata/function/generic/resolve_used.carbon
@@ -57,6 +57,7 @@ fn CallNegative() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/generic/return_slot.carbon b/toolchain/check/testdata/function/generic/return_slot.carbon
index a0b5567d01a2..3d7228008ea8 100644
--- a/toolchain/check/testdata/function/generic/return_slot.carbon
+++ b/toolchain/check/testdata/function/generic/return_slot.carbon
@@ -70,6 +70,7 @@ fn G() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/function/generic/undefined.carbon b/toolchain/check/testdata/function/generic/undefined.carbon
index ede87f397027..a166d63f51ce 100644
--- a/toolchain/check/testdata/function/generic/undefined.carbon
+++ b/toolchain/check/testdata/function/generic/undefined.carbon
@@ -74,6 +74,7 @@ fn CallUndefined() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -180,6 +181,7 @@ fn CallUndefined() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -302,6 +304,7 @@ fn CallUndefined() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/global/class_obj.carbon b/toolchain/check/testdata/global/class_obj.carbon
index e32d0292f988..4a86c727e326 100644
--- a/toolchain/check/testdata/global/class_obj.carbon
+++ b/toolchain/check/testdata/global/class_obj.carbon
@@ -29,6 +29,7 @@ var a: A = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/global/class_with_fun.carbon b/toolchain/check/testdata/global/class_with_fun.carbon
index 52e1de6123bc..0e25d279961e 100644
--- a/toolchain/check/testdata/global/class_with_fun.carbon
+++ b/toolchain/check/testdata/global/class_with_fun.carbon
@@ -35,6 +35,7 @@ var a: A = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/global/decl.carbon b/toolchain/check/testdata/global/decl.carbon
index 851ff00dfd0d..60a31e13e951 100644
--- a/toolchain/check/testdata/global/decl.carbon
+++ b/toolchain/check/testdata/global/decl.carbon
@@ -25,6 +25,7 @@ var a: i32;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/global/simple_init.carbon b/toolchain/check/testdata/global/simple_init.carbon
index 65039dadf03e..6be38e7804ee 100644
--- a/toolchain/check/testdata/global/simple_init.carbon
+++ b/toolchain/check/testdata/global/simple_init.carbon
@@ -26,6 +26,7 @@ var a: i32 = 0;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/global/simple_with_fun.carbon b/toolchain/check/testdata/global/simple_with_fun.carbon
index 04e66c7e98b0..38626bdc2414 100644
--- a/toolchain/check/testdata/global/simple_with_fun.carbon
+++ b/toolchain/check/testdata/global/simple_with_fun.carbon
@@ -33,6 +33,7 @@ var a: i32 = test_a();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if/else.carbon b/toolchain/check/testdata/if/else.carbon
index fcd788385b1b..fa878853c8e9 100644
--- a/toolchain/check/testdata/if/else.carbon
+++ b/toolchain/check/testdata/if/else.carbon
@@ -45,6 +45,7 @@ fn If(b: bool) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if/fail_reachable_fallthrough.carbon b/toolchain/check/testdata/if/fail_reachable_fallthrough.carbon
index a3fae2436044..dfe85299ba71 100644
--- a/toolchain/check/testdata/if/fail_reachable_fallthrough.carbon
+++ b/toolchain/check/testdata/if/fail_reachable_fallthrough.carbon
@@ -66,6 +66,7 @@ fn If3(b: bool) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if/fail_scope.carbon b/toolchain/check/testdata/if/fail_scope.carbon
index c0914dfeb9d7..7eb6ee555fab 100644
--- a/toolchain/check/testdata/if/fail_scope.carbon
+++ b/toolchain/check/testdata/if/fail_scope.carbon
@@ -41,6 +41,7 @@ fn VarScope(b: bool) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if/no_else.carbon b/toolchain/check/testdata/if/no_else.carbon
index be1ce4a08621..a6b0a489751c 100644
--- a/toolchain/check/testdata/if/no_else.carbon
+++ b/toolchain/check/testdata/if/no_else.carbon
@@ -40,6 +40,7 @@ fn If(b: bool) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if/unreachable_fallthrough.carbon b/toolchain/check/testdata/if/unreachable_fallthrough.carbon
index 6bc941228aa8..aba0a11249fd 100644
--- a/toolchain/check/testdata/if/unreachable_fallthrough.carbon
+++ b/toolchain/check/testdata/if/unreachable_fallthrough.carbon
@@ -40,6 +40,7 @@ fn If(b: bool) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if_expr/basic.carbon b/toolchain/check/testdata/if_expr/basic.carbon
index 4774f071bb0d..6dae484fcc0a 100644
--- a/toolchain/check/testdata/if_expr/basic.carbon
+++ b/toolchain/check/testdata/if_expr/basic.carbon
@@ -40,6 +40,7 @@ fn F(b: bool, n: i32, m: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if_expr/constant_condition.carbon b/toolchain/check/testdata/if_expr/constant_condition.carbon
index 281ce5518c45..ad835dbcb041 100644
--- a/toolchain/check/testdata/if_expr/constant_condition.carbon
+++ b/toolchain/check/testdata/if_expr/constant_condition.carbon
@@ -64,6 +64,7 @@ fn PartiallyConstant(t: type) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if_expr/control_flow.carbon b/toolchain/check/testdata/if_expr/control_flow.carbon
index e1e265365725..06ecc6b3fcc4 100644
--- a/toolchain/check/testdata/if_expr/control_flow.carbon
+++ b/toolchain/check/testdata/if_expr/control_flow.carbon
@@ -42,6 +42,7 @@ fn F(b: bool) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if_expr/fail_not_in_function.carbon b/toolchain/check/testdata/if_expr/fail_not_in_function.carbon
index e4b37dff0db4..e202a5ce45a2 100644
--- a/toolchain/check/testdata/if_expr/fail_not_in_function.carbon
+++ b/toolchain/check/testdata/if_expr/fail_not_in_function.carbon
@@ -64,6 +64,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if_expr/fail_partial_constant.carbon b/toolchain/check/testdata/if_expr/fail_partial_constant.carbon
index 74528338243a..cf3a575d23b8 100644
--- a/toolchain/check/testdata/if_expr/fail_partial_constant.carbon
+++ b/toolchain/check/testdata/if_expr/fail_partial_constant.carbon
@@ -61,6 +61,7 @@ fn ChosenBranchIsNonConstant(t: type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -138,6 +139,7 @@ fn ChosenBranchIsNonConstant(t: type) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if_expr/nested.carbon b/toolchain/check/testdata/if_expr/nested.carbon
index 1bcb43742aa1..3e01a72a8a51 100644
--- a/toolchain/check/testdata/if_expr/nested.carbon
+++ b/toolchain/check/testdata/if_expr/nested.carbon
@@ -37,6 +37,7 @@ fn F(a: bool, b: bool, c: bool) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/if_expr/struct.carbon b/toolchain/check/testdata/if_expr/struct.carbon
index 216a8af8cca7..f9f810ab29ad 100644
--- a/toolchain/check/testdata/if_expr/struct.carbon
+++ b/toolchain/check/testdata/if_expr/struct.carbon
@@ -43,6 +43,7 @@ fn F(cond: bool) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/compound.carbon b/toolchain/check/testdata/impl/compound.carbon
index 6bd79fd70e4a..dc65fcbe46ec 100644
--- a/toolchain/check/testdata/impl/compound.carbon
+++ b/toolchain/check/testdata/impl/compound.carbon
@@ -74,6 +74,7 @@ fn InstanceCallIndirect(p: i32*) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/declaration.carbon b/toolchain/check/testdata/impl/declaration.carbon
index cdb63e4f4ed8..58eec6e5a856 100644
--- a/toolchain/check/testdata/impl/declaration.carbon
+++ b/toolchain/check/testdata/impl/declaration.carbon
@@ -30,6 +30,7 @@ impl i32 as I;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/empty.carbon b/toolchain/check/testdata/impl/empty.carbon
index f278612ec1bc..87a76f97d288 100644
--- a/toolchain/check/testdata/impl/empty.carbon
+++ b/toolchain/check/testdata/impl/empty.carbon
@@ -33,6 +33,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/extend_impl.carbon b/toolchain/check/testdata/impl/extend_impl.carbon
index 5b602424dadf..1158613c976e 100644
--- a/toolchain/check/testdata/impl/extend_impl.carbon
+++ b/toolchain/check/testdata/impl/extend_impl.carbon
@@ -51,6 +51,7 @@ fn G(c: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_call_invalid.carbon b/toolchain/check/testdata/impl/fail_call_invalid.carbon
index 461f6b2c60d2..9ad6cfba5f88 100644
--- a/toolchain/check/testdata/impl/fail_call_invalid.carbon
+++ b/toolchain/check/testdata/impl/fail_call_invalid.carbon
@@ -49,6 +49,7 @@ fn InstanceCall(n: i32) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_extend_impl_forall.carbon b/toolchain/check/testdata/impl/fail_extend_impl_forall.carbon
index 0e9e85ec9cd4..21f261635c34 100644
--- a/toolchain/check/testdata/impl/fail_extend_impl_forall.carbon
+++ b/toolchain/check/testdata/impl/fail_extend_impl_forall.carbon
@@ -51,6 +51,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_extend_impl_scope.carbon b/toolchain/check/testdata/impl/fail_extend_impl_scope.carbon
index 33dc19781c60..f503b97580a7 100644
--- a/toolchain/check/testdata/impl/fail_extend_impl_scope.carbon
+++ b/toolchain/check/testdata/impl/fail_extend_impl_scope.carbon
@@ -34,6 +34,7 @@ extend impl i32 as I {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_extend_impl_type_as.carbon b/toolchain/check/testdata/impl/fail_extend_impl_type_as.carbon
index 3e3fc6da405a..a8037cc72428 100644
--- a/toolchain/check/testdata/impl/fail_extend_impl_type_as.carbon
+++ b/toolchain/check/testdata/impl/fail_extend_impl_type_as.carbon
@@ -63,6 +63,7 @@ class E {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_extend_non_interface.carbon b/toolchain/check/testdata/impl/fail_extend_non_interface.carbon
index 7004059742c6..45c023895664 100644
--- a/toolchain/check/testdata/impl/fail_extend_non_interface.carbon
+++ b/toolchain/check/testdata/impl/fail_extend_non_interface.carbon
@@ -34,6 +34,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_extend_partially_defined_interface.carbon b/toolchain/check/testdata/impl/fail_extend_partially_defined_interface.carbon
index 6ff9ec5f9787..ffca24094c82 100644
--- a/toolchain/check/testdata/impl/fail_extend_partially_defined_interface.carbon
+++ b/toolchain/check/testdata/impl/fail_extend_partially_defined_interface.carbon
@@ -38,6 +38,7 @@ interface I {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_extend_undefined_interface.carbon b/toolchain/check/testdata/impl/fail_extend_undefined_interface.carbon
index 9fbd8770159c..95b396a9e543 100644
--- a/toolchain/check/testdata/impl/fail_extend_undefined_interface.carbon
+++ b/toolchain/check/testdata/impl/fail_extend_undefined_interface.carbon
@@ -36,6 +36,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_impl_as_scope.carbon b/toolchain/check/testdata/impl/fail_impl_as_scope.carbon
index 47ca6f34f7ec..2981cc508231 100644
--- a/toolchain/check/testdata/impl/fail_impl_as_scope.carbon
+++ b/toolchain/check/testdata/impl/fail_impl_as_scope.carbon
@@ -41,6 +41,7 @@ impl as Simple {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_impl_bad_assoc_const.carbon b/toolchain/check/testdata/impl/fail_impl_bad_assoc_const.carbon
index 2c6dace5f392..e4da1177736e 100644
--- a/toolchain/check/testdata/impl/fail_impl_bad_assoc_const.carbon
+++ b/toolchain/check/testdata/impl/fail_impl_bad_assoc_const.carbon
@@ -35,6 +35,7 @@ impl bool as I {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon b/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon
index 560bdddeca01..d46b45fa3749 100644
--- a/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon
+++ b/toolchain/check/testdata/impl/fail_impl_bad_assoc_fn.carbon
@@ -310,6 +310,7 @@ class SelfNestedBadReturnType {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_impl_bad_interface.carbon b/toolchain/check/testdata/impl/fail_impl_bad_interface.carbon
index f5e5c8480b91..e0ec60ce9fdc 100644
--- a/toolchain/check/testdata/impl/fail_impl_bad_interface.carbon
+++ b/toolchain/check/testdata/impl/fail_impl_bad_interface.carbon
@@ -55,6 +55,7 @@ impl i32 as false {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_redefinition.carbon b/toolchain/check/testdata/impl/fail_redefinition.carbon
index 04fabb3f1674..1dafbaa5649c 100644
--- a/toolchain/check/testdata/impl/fail_redefinition.carbon
+++ b/toolchain/check/testdata/impl/fail_redefinition.carbon
@@ -39,6 +39,7 @@ impl i32 as I {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/fail_todo_impl_assoc_const.carbon b/toolchain/check/testdata/impl/fail_todo_impl_assoc_const.carbon
index 2a69521c6ecd..58482e589f1d 100644
--- a/toolchain/check/testdata/impl/fail_todo_impl_assoc_const.carbon
+++ b/toolchain/check/testdata/impl/fail_todo_impl_assoc_const.carbon
@@ -61,6 +61,7 @@ impl bool as I where .T = bool {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/impl_as.carbon b/toolchain/check/testdata/impl/impl_as.carbon
index c4e87e4273cd..6c6943a781d1 100644
--- a/toolchain/check/testdata/impl/impl_as.carbon
+++ b/toolchain/check/testdata/impl/impl_as.carbon
@@ -48,6 +48,7 @@ class C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/impl_forall.carbon b/toolchain/check/testdata/impl/impl_forall.carbon
index 41edeae70e5f..177a46351b96 100644
--- a/toolchain/check/testdata/impl/impl_forall.carbon
+++ b/toolchain/check/testdata/impl/impl_forall.carbon
@@ -40,6 +40,7 @@ impl forall [T:! type] T as Simple {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/lookup/alias.carbon b/toolchain/check/testdata/impl/lookup/alias.carbon
index e35bf09891cd..f4b7e50495c1 100644
--- a/toolchain/check/testdata/impl/lookup/alias.carbon
+++ b/toolchain/check/testdata/impl/lookup/alias.carbon
@@ -53,6 +53,7 @@ fn G(c: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/lookup/fail_alias_impl_not_found.carbon b/toolchain/check/testdata/impl/lookup/fail_alias_impl_not_found.carbon
index 8ff5dc0287fb..ad4973c78a79 100644
--- a/toolchain/check/testdata/impl/lookup/fail_alias_impl_not_found.carbon
+++ b/toolchain/check/testdata/impl/lookup/fail_alias_impl_not_found.carbon
@@ -53,6 +53,7 @@ fn F(c: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/lookup/fail_todo_undefined_impl.carbon b/toolchain/check/testdata/impl/lookup/fail_todo_undefined_impl.carbon
index 0c21538ec610..232645a4be2a 100644
--- a/toolchain/check/testdata/impl/lookup/fail_todo_undefined_impl.carbon
+++ b/toolchain/check/testdata/impl/lookup/fail_todo_undefined_impl.carbon
@@ -59,6 +59,7 @@ impl C as I {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/lookup/generic.carbon b/toolchain/check/testdata/impl/lookup/generic.carbon
index 30746ccc4a38..1bffc1c7aaaf 100644
--- a/toolchain/check/testdata/impl/lookup/generic.carbon
+++ b/toolchain/check/testdata/impl/lookup/generic.carbon
@@ -152,6 +152,7 @@ fn G(x: A) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -307,6 +308,7 @@ fn G(x: A) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -520,6 +522,7 @@ fn G(x: A) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -730,6 +733,7 @@ fn G(x: A) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -949,6 +953,7 @@ fn G(x: A) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1105,6 +1110,7 @@ fn G(x: A) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/lookup/instance_method.carbon b/toolchain/check/testdata/impl/lookup/instance_method.carbon
index 90818a0c2141..6860a0b7b306 100644
--- a/toolchain/check/testdata/impl/lookup/instance_method.carbon
+++ b/toolchain/check/testdata/impl/lookup/instance_method.carbon
@@ -55,6 +55,7 @@ fn F(c: C) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/impl/redeclaration.carbon b/toolchain/check/testdata/impl/redeclaration.carbon
index cd5f92d6b2da..e4572c4c2308 100644
--- a/toolchain/check/testdata/impl/redeclaration.carbon
+++ b/toolchain/check/testdata/impl/redeclaration.carbon
@@ -40,6 +40,7 @@ impl i32 as I {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/index/array_element_access.carbon b/toolchain/check/testdata/index/array_element_access.carbon
index 2fdde70bf98c..d3c49e0226c4 100644
--- a/toolchain/check/testdata/index/array_element_access.carbon
+++ b/toolchain/check/testdata/index/array_element_access.carbon
@@ -38,6 +38,7 @@ var d: i32 = a[b];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/index/expr_category.carbon b/toolchain/check/testdata/index/expr_category.carbon
index 6e45e72d1c92..bf2154e8b299 100644
--- a/toolchain/check/testdata/index/expr_category.carbon
+++ b/toolchain/check/testdata/index/expr_category.carbon
@@ -60,6 +60,7 @@ fn ValueBinding(b: [i32; 3]) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/index/fail_array_large_index.carbon b/toolchain/check/testdata/index/fail_array_large_index.carbon
index 9f439925fcee..dfbf2dcf9f49 100644
--- a/toolchain/check/testdata/index/fail_array_large_index.carbon
+++ b/toolchain/check/testdata/index/fail_array_large_index.carbon
@@ -45,6 +45,7 @@ var c: i32 = a[0x7FFF_FFFF];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/index/fail_array_non_int_indexing.carbon b/toolchain/check/testdata/index/fail_array_non_int_indexing.carbon
index c815b3f6786e..5ea860ef26fd 100644
--- a/toolchain/check/testdata/index/fail_array_non_int_indexing.carbon
+++ b/toolchain/check/testdata/index/fail_array_non_int_indexing.carbon
@@ -59,6 +59,7 @@ var b: i32 = a[2.6];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/index/fail_array_out_of_bound_access.carbon b/toolchain/check/testdata/index/fail_array_out_of_bound_access.carbon
index 961fdf5c6ae1..180b668d7684 100644
--- a/toolchain/check/testdata/index/fail_array_out_of_bound_access.carbon
+++ b/toolchain/check/testdata/index/fail_array_out_of_bound_access.carbon
@@ -37,6 +37,7 @@ var b: i32 = a[1];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/index/fail_expr_category.carbon b/toolchain/check/testdata/index/fail_expr_category.carbon
index fc2cf82fb0a8..21ccd85db57c 100644
--- a/toolchain/check/testdata/index/fail_expr_category.carbon
+++ b/toolchain/check/testdata/index/fail_expr_category.carbon
@@ -62,6 +62,7 @@ fn G(b: [i32; 3]) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/index/fail_invalid_base.carbon b/toolchain/check/testdata/index/fail_invalid_base.carbon
index be9a64028733..050d751a6776 100644
--- a/toolchain/check/testdata/index/fail_invalid_base.carbon
+++ b/toolchain/check/testdata/index/fail_invalid_base.carbon
@@ -47,21 +47,41 @@ var d: i32 = {.a: i32, .b: i32}[0];
 // CHECK:STDOUT:   %.5: type = struct_type {.a: i32, .b: i32} [template]
 // CHECK:STDOUT:   %.6: type = ptr_type %.5 [template]
 // CHECK:STDOUT:   %struct: %.5 = struct_value (%.3, %.4) [template]
+// CHECK:STDOUT:   %IndexWith.type.1: type = generic_interface_type @IndexWith [template]
+// CHECK:STDOUT:   %IndexWith: %IndexWith.type.1 = struct_value () [template]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.2: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2) = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %Self.2: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %At.type: type = fn_type @At, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %At: %At.type = struct_value () [symbolic]
+// CHECK:STDOUT:   %.7: type = assoc_entity_type %IndexWith.type.2, %At.type [symbolic]
+// CHECK:STDOUT:   %.8: %.7 = assoc_entity element0, imports.%import_ref.6 [symbolic]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
-// CHECK:STDOUT:     .Int32 = %import_ref
+// CHECK:STDOUT:     .Int32 = %import_ref.1
+// CHECK:STDOUT:     .IndexWith = %import_ref.2
 // CHECK:STDOUT:     import Core//prelude
 // CHECK:STDOUT:     import Core//prelude/operators
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %import_ref: %Int32.type = import_ref Core//prelude/types, inst+15, loaded [template = constants.%Int32]
+// CHECK:STDOUT:   %import_ref.1: %Int32.type = import_ref Core//prelude/types, inst+15, loaded [template = constants.%Int32]
+// CHECK:STDOUT:   %import_ref.2: %IndexWith.type.1 = import_ref Core//prelude/operators/index, inst+13, loaded [template = constants.%IndexWith]
+// CHECK:STDOUT:   %import_ref.3 = import_ref Core//prelude/operators/index, inst+22, unloaded
+// CHECK:STDOUT:   %import_ref.4 = import_ref Core//prelude/operators/index, inst+50, unloaded
+// CHECK:STDOUT:   %import_ref.5 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT:   %import_ref.6 = import_ref Core//prelude/operators/index, inst+42, unloaded
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
@@ -99,10 +119,41 @@ var d: i32 = {.a: i32, .b: i32}[0];
 // CHECK:STDOUT:   %d: ref i32 = bind_name d, %d.var
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: generic interface @IndexWith(constants.%SubscriptType: type, constants.%ElementType: type) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic = %SubscriptType.patt (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic = %ElementType.patt (constants.%ElementType.patt)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:   %At.type: type = fn_type @At, @IndexWith(%SubscriptType, %ElementType) [symbolic = %At.type (constants.%At.type)]
+// CHECK:STDOUT:   %At: @IndexWith.%At.type (%At.type) = struct_value () [symbolic = %At (constants.%At)]
+// CHECK:STDOUT:   %.1: type = assoc_entity_type @IndexWith.%IndexWith.type (%IndexWith.type.2), @IndexWith.%At.type (%At.type) [symbolic = %.1 (constants.%.7)]
+// CHECK:STDOUT:   %.2: @IndexWith.%.1 (%.7) = assoc_entity element0, imports.%import_ref.6 [symbolic = %.2 (constants.%.8)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   interface {
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = imports.%import_ref.3
+// CHECK:STDOUT:     .At = imports.%import_ref.4
+// CHECK:STDOUT:     witness = (imports.%import_ref.5)
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
 // CHECK:STDOUT: fn @Int32() -> type = "int.make_type_32";
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F();
 // CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @At(constants.%SubscriptType: type, constants.%ElementType: type, constants.%Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2)) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn[%self.param_patt: @At.%Self (%Self.2)](%subscript.param_patt: @At.%SubscriptType (%SubscriptType)) -> @At.%ElementType (%ElementType);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
 // CHECK:STDOUT: fn @__global_init() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %N.ref: <namespace> = name_ref N, file.%N [template = file.%N]
@@ -130,3 +181,31 @@ var d: i32 = {.a: i32, .b: i32}[0];
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType, constants.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@IndexWith.%SubscriptType, @IndexWith.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@At.%SubscriptType, @At.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At(constants.%SubscriptType, constants.%ElementType, constants.%Self.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.2
+// CHECK:STDOUT:   %Self => constants.%Self.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
diff --git a/toolchain/check/testdata/index/fail_name_not_found.carbon b/toolchain/check/testdata/index/fail_name_not_found.carbon
index 18cc48b891be..4ddbe19980e7 100644
--- a/toolchain/check/testdata/index/fail_name_not_found.carbon
+++ b/toolchain/check/testdata/index/fail_name_not_found.carbon
@@ -34,6 +34,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/index/fail_negative_indexing.carbon b/toolchain/check/testdata/index/fail_negative_indexing.carbon
index 1cb9582dcb87..61999cd80835 100644
--- a/toolchain/check/testdata/index/fail_negative_indexing.carbon
+++ b/toolchain/check/testdata/index/fail_negative_indexing.carbon
@@ -47,6 +47,7 @@ var d: i32 = c[-10];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/index/fail_non_tuple_access.carbon b/toolchain/check/testdata/index/fail_non_tuple_access.carbon
index 7a3045982876..54fe5543e5db 100644
--- a/toolchain/check/testdata/index/fail_non_tuple_access.carbon
+++ b/toolchain/check/testdata/index/fail_non_tuple_access.carbon
@@ -23,19 +23,39 @@ fn Main() {
 // CHECK:STDOUT:   %Main: %Main.type = struct_value () [template]
 // CHECK:STDOUT:   %.2: i32 = int_literal 0 [template]
 // CHECK:STDOUT:   %.3: i32 = int_literal 1 [template]
+// CHECK:STDOUT:   %IndexWith.type.1: type = generic_interface_type @IndexWith [template]
+// CHECK:STDOUT:   %IndexWith: %IndexWith.type.1 = struct_value () [template]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.2: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2) = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %Self.2: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %At.type: type = fn_type @At, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %At: %At.type = struct_value () [symbolic]
+// CHECK:STDOUT:   %.4: type = assoc_entity_type %IndexWith.type.2, %At.type [symbolic]
+// CHECK:STDOUT:   %.5: %.4 = assoc_entity element0, imports.%import_ref.5 [symbolic]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
+// CHECK:STDOUT:     .IndexWith = %import_ref.1
 // CHECK:STDOUT:     import Core//prelude
 // CHECK:STDOUT:     import Core//prelude/operators
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %import_ref.1: %IndexWith.type.1 = import_ref Core//prelude/operators/index, inst+13, loaded [template = constants.%IndexWith]
+// CHECK:STDOUT:   %import_ref.2 = import_ref Core//prelude/operators/index, inst+22, unloaded
+// CHECK:STDOUT:   %import_ref.3 = import_ref Core//prelude/operators/index, inst+50, unloaded
+// CHECK:STDOUT:   %import_ref.4 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT:   %import_ref.5 = import_ref Core//prelude/operators/index, inst+42, unloaded
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
@@ -47,6 +67,28 @@ fn Main() {
 // CHECK:STDOUT:   %Main.decl: %Main.type = fn_decl @Main [template = constants.%Main] {} {}
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: generic interface @IndexWith(constants.%SubscriptType: type, constants.%ElementType: type) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic = %SubscriptType.patt (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic = %ElementType.patt (constants.%ElementType.patt)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:   %At.type: type = fn_type @At, @IndexWith(%SubscriptType, %ElementType) [symbolic = %At.type (constants.%At.type)]
+// CHECK:STDOUT:   %At: @IndexWith.%At.type (%At.type) = struct_value () [symbolic = %At (constants.%At)]
+// CHECK:STDOUT:   %.1: type = assoc_entity_type @IndexWith.%IndexWith.type (%IndexWith.type.2), @IndexWith.%At.type (%At.type) [symbolic = %.1 (constants.%.4)]
+// CHECK:STDOUT:   %.2: @IndexWith.%.1 (%.4) = assoc_entity element0, imports.%import_ref.5 [symbolic = %.2 (constants.%.5)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   interface {
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = imports.%import_ref.2
+// CHECK:STDOUT:     .At = imports.%import_ref.3
+// CHECK:STDOUT:     witness = (imports.%import_ref.4)
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
 // CHECK:STDOUT: fn @Main() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %.loc15_3: i32 = int_literal 0 [template = constants.%.2]
@@ -54,3 +96,40 @@ fn Main() {
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @At(constants.%SubscriptType: type, constants.%ElementType: type, constants.%Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2)) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn[%self.param_patt: @At.%Self (%Self.2)](%subscript.param_patt: @At.%SubscriptType (%SubscriptType)) -> @At.%ElementType (%ElementType);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType, constants.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@IndexWith.%SubscriptType, @IndexWith.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@At.%SubscriptType, @At.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At(constants.%SubscriptType, constants.%ElementType, constants.%Self.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.2
+// CHECK:STDOUT:   %Self => constants.%Self.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
diff --git a/toolchain/check/testdata/interface/assoc_const.carbon b/toolchain/check/testdata/interface/assoc_const.carbon
index c800141ea392..065ed6b18205 100644
--- a/toolchain/check/testdata/interface/assoc_const.carbon
+++ b/toolchain/check/testdata/interface/assoc_const.carbon
@@ -35,6 +35,7 @@ interface I {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/interface/fail_assoc_const_bad_default.carbon b/toolchain/check/testdata/interface/fail_assoc_const_bad_default.carbon
index 1e6602ab3f46..ab316921cf15 100644
--- a/toolchain/check/testdata/interface/fail_assoc_const_bad_default.carbon
+++ b/toolchain/check/testdata/interface/fail_assoc_const_bad_default.carbon
@@ -54,6 +54,7 @@ interface I {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/interface/fail_todo_assoc_const_default.carbon b/toolchain/check/testdata/interface/fail_todo_assoc_const_default.carbon
index 4569ecc6bbee..4566a48a1ff1 100644
--- a/toolchain/check/testdata/interface/fail_todo_assoc_const_default.carbon
+++ b/toolchain/check/testdata/interface/fail_todo_assoc_const_default.carbon
@@ -45,6 +45,7 @@ interface I {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/interface/fail_todo_define_default_fn_inline.carbon b/toolchain/check/testdata/interface/fail_todo_define_default_fn_inline.carbon
index 993d81fb1014..12176afd7f14 100644
--- a/toolchain/check/testdata/interface/fail_todo_define_default_fn_inline.carbon
+++ b/toolchain/check/testdata/interface/fail_todo_define_default_fn_inline.carbon
@@ -47,6 +47,7 @@ interface Interface {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/interface/fail_todo_define_default_fn_out_of_line.carbon b/toolchain/check/testdata/interface/fail_todo_define_default_fn_out_of_line.carbon
index a9fbc475cbb8..a671618a27d1 100644
--- a/toolchain/check/testdata/interface/fail_todo_define_default_fn_out_of_line.carbon
+++ b/toolchain/check/testdata/interface/fail_todo_define_default_fn_out_of_line.carbon
@@ -93,6 +93,7 @@ fn Interface.C.F[self: Self](U:! type, u: U) -> U { return u; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -230,6 +231,7 @@ fn Interface.C.F[self: Self](U:! type, u: U) -> U { return u; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/interface/todo_define_not_default.carbon b/toolchain/check/testdata/interface/todo_define_not_default.carbon
index 579477a5d827..09dfb2bf42b3 100644
--- a/toolchain/check/testdata/interface/todo_define_not_default.carbon
+++ b/toolchain/check/testdata/interface/todo_define_not_default.carbon
@@ -52,6 +52,7 @@ interface I {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/ir/duplicate_name_same_line.carbon b/toolchain/check/testdata/ir/duplicate_name_same_line.carbon
index de6ea37db9aa..18f046ff1ab0 100644
--- a/toolchain/check/testdata/ir/duplicate_name_same_line.carbon
+++ b/toolchain/check/testdata/ir/duplicate_name_same_line.carbon
@@ -31,6 +31,7 @@ fn A() { if (true) { var n: i32 = 1; } if (true) { var n: i32 = 2; } }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/compile_time_bindings.carbon b/toolchain/check/testdata/let/compile_time_bindings.carbon
index c26c495adca8..a5976c9a5d03 100644
--- a/toolchain/check/testdata/let/compile_time_bindings.carbon
+++ b/toolchain/check/testdata/let/compile_time_bindings.carbon
@@ -181,6 +181,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -245,6 +246,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -320,6 +322,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -504,6 +507,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -568,6 +572,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -628,6 +633,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -716,6 +722,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -858,6 +865,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -917,6 +925,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -974,6 +983,7 @@ impl i32 as Empty {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/convert.carbon b/toolchain/check/testdata/let/convert.carbon
index 9081a5dfb1ac..581d016d22f0 100644
--- a/toolchain/check/testdata/let/convert.carbon
+++ b/toolchain/check/testdata/let/convert.carbon
@@ -40,6 +40,7 @@ fn F() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/fail_duplicate_decl.carbon b/toolchain/check/testdata/let/fail_duplicate_decl.carbon
index d2318f96dbed..71a180e6f583 100644
--- a/toolchain/check/testdata/let/fail_duplicate_decl.carbon
+++ b/toolchain/check/testdata/let/fail_duplicate_decl.carbon
@@ -39,6 +39,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/fail_generic.carbon b/toolchain/check/testdata/let/fail_generic.carbon
index 324d2d527204..a32c62961301 100644
--- a/toolchain/check/testdata/let/fail_generic.carbon
+++ b/toolchain/check/testdata/let/fail_generic.carbon
@@ -71,6 +71,7 @@ fn F(a: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/fail_generic_import.carbon b/toolchain/check/testdata/let/fail_generic_import.carbon
index 084e45c2172f..85c02b03a628 100644
--- a/toolchain/check/testdata/let/fail_generic_import.carbon
+++ b/toolchain/check/testdata/let/fail_generic_import.carbon
@@ -44,6 +44,7 @@ let a: T = 0;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -84,6 +85,7 @@ let a: T = 0;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/fail_missing_value.carbon b/toolchain/check/testdata/let/fail_missing_value.carbon
index 8c8beab0a92a..2960f8b9ab37 100644
--- a/toolchain/check/testdata/let/fail_missing_value.carbon
+++ b/toolchain/check/testdata/let/fail_missing_value.carbon
@@ -39,6 +39,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/fail_modifiers.carbon b/toolchain/check/testdata/let/fail_modifiers.carbon
index 7b9dfde77c9c..c3a443b8f7b9 100644
--- a/toolchain/check/testdata/let/fail_modifiers.carbon
+++ b/toolchain/check/testdata/let/fail_modifiers.carbon
@@ -100,6 +100,7 @@ protected protected let i: i32 = 1;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/fail_use_in_init.carbon b/toolchain/check/testdata/let/fail_use_in_init.carbon
index 5d6f24dcfcc4..d6f26b899b03 100644
--- a/toolchain/check/testdata/let/fail_use_in_init.carbon
+++ b/toolchain/check/testdata/let/fail_use_in_init.carbon
@@ -33,6 +33,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/generic.carbon b/toolchain/check/testdata/let/generic.carbon
index 43393ce59955..a1768753b480 100644
--- a/toolchain/check/testdata/let/generic.carbon
+++ b/toolchain/check/testdata/let/generic.carbon
@@ -34,6 +34,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/generic_import.carbon b/toolchain/check/testdata/let/generic_import.carbon
index e4f40124239b..525d94eb78c0 100644
--- a/toolchain/check/testdata/let/generic_import.carbon
+++ b/toolchain/check/testdata/let/generic_import.carbon
@@ -48,6 +48,7 @@ var b: T = *a;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -84,6 +85,7 @@ var b: T = *a;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/global.carbon b/toolchain/check/testdata/let/global.carbon
index f4f53395a25c..a324f80164e8 100644
--- a/toolchain/check/testdata/let/global.carbon
+++ b/toolchain/check/testdata/let/global.carbon
@@ -31,6 +31,7 @@ fn F() -> i32 { return n; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/local.carbon b/toolchain/check/testdata/let/local.carbon
index 0a33e6307a65..78c90d6b6bbd 100644
--- a/toolchain/check/testdata/let/local.carbon
+++ b/toolchain/check/testdata/let/local.carbon
@@ -31,6 +31,7 @@ fn F(a: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/let/shadowed_decl.carbon b/toolchain/check/testdata/let/shadowed_decl.carbon
index 0022f44a46c0..5179ef56127f 100644
--- a/toolchain/check/testdata/let/shadowed_decl.carbon
+++ b/toolchain/check/testdata/let/shadowed_decl.carbon
@@ -33,6 +33,7 @@ fn F(a: i32) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/add_to_import.carbon b/toolchain/check/testdata/namespace/add_to_import.carbon
index 44aefbd72dc4..6d0d2615a92f 100644
--- a/toolchain/check/testdata/namespace/add_to_import.carbon
+++ b/toolchain/check/testdata/namespace/add_to_import.carbon
@@ -31,6 +31,7 @@ var a: i32 = NS.A();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -69,6 +70,7 @@ var a: i32 = NS.A();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/alias.carbon b/toolchain/check/testdata/namespace/alias.carbon
index b7d2f022c67a..79098248a481 100644
--- a/toolchain/check/testdata/namespace/alias.carbon
+++ b/toolchain/check/testdata/namespace/alias.carbon
@@ -43,6 +43,7 @@ fn D() -> i32 { return C(); }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_conflict_after_merge.carbon b/toolchain/check/testdata/namespace/fail_conflict_after_merge.carbon
index 67cce27602e8..222064a71ba1 100644
--- a/toolchain/check/testdata/namespace/fail_conflict_after_merge.carbon
+++ b/toolchain/check/testdata/namespace/fail_conflict_after_merge.carbon
@@ -56,6 +56,7 @@ fn NS();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -90,6 +91,7 @@ fn NS();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_first.carbon b/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_first.carbon
index f35a81488139..80038c06d0ae 100644
--- a/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_first.carbon
+++ b/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_first.carbon
@@ -40,6 +40,7 @@ fn NS.Foo();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -76,6 +77,7 @@ fn NS.Foo();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_nested.carbon b/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_nested.carbon
index 375316e7dbf1..abc839537a3f 100644
--- a/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_nested.carbon
+++ b/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_nested.carbon
@@ -42,6 +42,7 @@ fn Other.Nested.F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -72,6 +73,7 @@ fn Other.Nested.F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_second.carbon b/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_second.carbon
index 95d486bc2339..75014c3914b5 100644
--- a/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_second.carbon
+++ b/toolchain/check/testdata/namespace/fail_conflict_imported_namespace_second.carbon
@@ -54,6 +54,7 @@ fn NS.Foo();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -89,6 +90,7 @@ fn NS.Foo();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_conflict_in_imports_namespace_first.carbon b/toolchain/check/testdata/namespace/fail_conflict_in_imports_namespace_first.carbon
index 4d1e94bf0d63..a4211b651e5f 100644
--- a/toolchain/check/testdata/namespace/fail_conflict_in_imports_namespace_first.carbon
+++ b/toolchain/check/testdata/namespace/fail_conflict_in_imports_namespace_first.carbon
@@ -53,6 +53,7 @@ fn NS.Bar() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -91,6 +92,7 @@ fn NS.Bar() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -133,6 +135,7 @@ fn NS.Bar() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_conflict_in_imports_namespace_second.carbon b/toolchain/check/testdata/namespace/fail_conflict_in_imports_namespace_second.carbon
index f2a7b2e20a2b..03996a387434 100644
--- a/toolchain/check/testdata/namespace/fail_conflict_in_imports_namespace_second.carbon
+++ b/toolchain/check/testdata/namespace/fail_conflict_in_imports_namespace_second.carbon
@@ -53,6 +53,7 @@ fn NS.Bar() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -88,6 +89,7 @@ fn NS.Bar() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -133,6 +135,7 @@ fn NS.Bar() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_decl_in_alias.carbon b/toolchain/check/testdata/namespace/fail_decl_in_alias.carbon
index 1e233065c4dc..b6ea14f15661 100644
--- a/toolchain/check/testdata/namespace/fail_decl_in_alias.carbon
+++ b/toolchain/check/testdata/namespace/fail_decl_in_alias.carbon
@@ -40,6 +40,7 @@ fn ns.A() -> i32 { return 0; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_duplicate.carbon b/toolchain/check/testdata/namespace/fail_duplicate.carbon
index 0a0391f45114..ff77cad2016e 100644
--- a/toolchain/check/testdata/namespace/fail_duplicate.carbon
+++ b/toolchain/check/testdata/namespace/fail_duplicate.carbon
@@ -37,6 +37,7 @@ fn Foo.Baz() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_modifiers.carbon b/toolchain/check/testdata/namespace/fail_modifiers.carbon
index b276bdc10e81..1056980b1073 100644
--- a/toolchain/check/testdata/namespace/fail_modifiers.carbon
+++ b/toolchain/check/testdata/namespace/fail_modifiers.carbon
@@ -63,6 +63,7 @@ extern namespace C;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_params.carbon b/toolchain/check/testdata/namespace/fail_params.carbon
index 5a627d7025f3..b7986ca7feb3 100644
--- a/toolchain/check/testdata/namespace/fail_params.carbon
+++ b/toolchain/check/testdata/namespace/fail_params.carbon
@@ -61,6 +61,7 @@ fn D(T:! type).F() {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/fail_unresolved_scope.carbon b/toolchain/check/testdata/namespace/fail_unresolved_scope.carbon
index e975f653f330..fe4fe26fc231 100644
--- a/toolchain/check/testdata/namespace/fail_unresolved_scope.carbon
+++ b/toolchain/check/testdata/namespace/fail_unresolved_scope.carbon
@@ -29,6 +29,7 @@ fn Foo.Baz() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/function.carbon b/toolchain/check/testdata/namespace/function.carbon
index 9702fd86be25..f380af262cff 100644
--- a/toolchain/check/testdata/namespace/function.carbon
+++ b/toolchain/check/testdata/namespace/function.carbon
@@ -40,6 +40,7 @@ fn Bar() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/imported.carbon b/toolchain/check/testdata/namespace/imported.carbon
index db35a14298da..8e6315fe1043 100644
--- a/toolchain/check/testdata/namespace/imported.carbon
+++ b/toolchain/check/testdata/namespace/imported.carbon
@@ -45,6 +45,7 @@ var package_b: () = package.NS.ChildNS.B();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -100,6 +101,7 @@ var package_b: () = package.NS.ChildNS.B();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/imported_indirect.carbon b/toolchain/check/testdata/namespace/imported_indirect.carbon
index ecf281c0b69b..453bd1df3af0 100644
--- a/toolchain/check/testdata/namespace/imported_indirect.carbon
+++ b/toolchain/check/testdata/namespace/imported_indirect.carbon
@@ -51,6 +51,7 @@ var e: () = A.B.C.D();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -79,6 +80,7 @@ var e: () = A.B.C.D();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -112,6 +114,7 @@ var e: () = A.B.C.D();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -155,6 +158,7 @@ var e: () = A.B.C.D();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -204,6 +208,7 @@ var e: () = A.B.C.D();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/merging.carbon b/toolchain/check/testdata/namespace/merging.carbon
index 1e319f3b0aaf..3aa3a651be99 100644
--- a/toolchain/check/testdata/namespace/merging.carbon
+++ b/toolchain/check/testdata/namespace/merging.carbon
@@ -61,6 +61,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -101,6 +102,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -168,6 +170,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/merging_with_indirections.carbon b/toolchain/check/testdata/namespace/merging_with_indirections.carbon
index 6b06159b1378..b5dcf4f5679c 100644
--- a/toolchain/check/testdata/namespace/merging_with_indirections.carbon
+++ b/toolchain/check/testdata/namespace/merging_with_indirections.carbon
@@ -56,6 +56,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -108,6 +109,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -180,6 +182,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/nested.carbon b/toolchain/check/testdata/namespace/nested.carbon
index 086da226af27..f5a2dc339923 100644
--- a/toolchain/check/testdata/namespace/nested.carbon
+++ b/toolchain/check/testdata/namespace/nested.carbon
@@ -35,6 +35,7 @@ fn Foo.Bar.Baz() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/shadow.carbon b/toolchain/check/testdata/namespace/shadow.carbon
index a97145e48ba9..6606f92948ba 100644
--- a/toolchain/check/testdata/namespace/shadow.carbon
+++ b/toolchain/check/testdata/namespace/shadow.carbon
@@ -51,6 +51,7 @@ fn N.M.B() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/namespace/unqualified_lookup.carbon b/toolchain/check/testdata/namespace/unqualified_lookup.carbon
index 525c64bb34fd..2d44de93f9f5 100644
--- a/toolchain/check/testdata/namespace/unqualified_lookup.carbon
+++ b/toolchain/check/testdata/namespace/unqualified_lookup.carbon
@@ -55,6 +55,7 @@ fn OuterN.InnerN.CallABC() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/and.carbon b/toolchain/check/testdata/operators/builtin/and.carbon
index 4c3ff6174de5..403607b1850b 100644
--- a/toolchain/check/testdata/operators/builtin/and.carbon
+++ b/toolchain/check/testdata/operators/builtin/and.carbon
@@ -55,6 +55,7 @@ fn PartialConstant(x: bool) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/assignment.carbon b/toolchain/check/testdata/operators/builtin/assignment.carbon
index 2241edd9d94f..49ca47f31108 100644
--- a/toolchain/check/testdata/operators/builtin/assignment.carbon
+++ b/toolchain/check/testdata/operators/builtin/assignment.carbon
@@ -62,6 +62,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/fail_and_or_not_in_function.carbon b/toolchain/check/testdata/operators/builtin/fail_and_or_not_in_function.carbon
index ab9d14de4faa..7a9f9330676d 100644
--- a/toolchain/check/testdata/operators/builtin/fail_and_or_not_in_function.carbon
+++ b/toolchain/check/testdata/operators/builtin/fail_and_or_not_in_function.carbon
@@ -68,6 +68,7 @@ var or_: F(true or true);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/fail_and_or_partial_constant.carbon b/toolchain/check/testdata/operators/builtin/fail_and_or_partial_constant.carbon
index 2d5ac11d30b3..3173b750c00f 100644
--- a/toolchain/check/testdata/operators/builtin/fail_and_or_partial_constant.carbon
+++ b/toolchain/check/testdata/operators/builtin/fail_and_or_partial_constant.carbon
@@ -63,6 +63,7 @@ fn KnownValueButNonConstantCondition(x: bool) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -170,6 +171,7 @@ fn KnownValueButNonConstantCondition(x: bool) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/fail_assignment_to_error.carbon b/toolchain/check/testdata/operators/builtin/fail_assignment_to_error.carbon
index 482b6ff75d84..cc3a3ff85497 100644
--- a/toolchain/check/testdata/operators/builtin/fail_assignment_to_error.carbon
+++ b/toolchain/check/testdata/operators/builtin/fail_assignment_to_error.carbon
@@ -36,6 +36,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/fail_assignment_to_non_assignable.carbon b/toolchain/check/testdata/operators/builtin/fail_assignment_to_non_assignable.carbon
index 78d39a85c7d4..594ad9e83396 100644
--- a/toolchain/check/testdata/operators/builtin/fail_assignment_to_non_assignable.carbon
+++ b/toolchain/check/testdata/operators/builtin/fail_assignment_to_non_assignable.carbon
@@ -92,6 +92,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/fail_redundant_compound_access.carbon b/toolchain/check/testdata/operators/builtin/fail_redundant_compound_access.carbon
index a907e0ab2cf1..87b303a2ed9d 100644
--- a/toolchain/check/testdata/operators/builtin/fail_redundant_compound_access.carbon
+++ b/toolchain/check/testdata/operators/builtin/fail_redundant_compound_access.carbon
@@ -45,6 +45,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/fail_type_mismatch.carbon b/toolchain/check/testdata/operators/builtin/fail_type_mismatch.carbon
index 8e77d43d888a..4935648b0f33 100644
--- a/toolchain/check/testdata/operators/builtin/fail_type_mismatch.carbon
+++ b/toolchain/check/testdata/operators/builtin/fail_type_mismatch.carbon
@@ -55,6 +55,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/fail_type_mismatch_assignment.carbon b/toolchain/check/testdata/operators/builtin/fail_type_mismatch_assignment.carbon
index 482ab2589d9c..721f95ce6c64 100644
--- a/toolchain/check/testdata/operators/builtin/fail_type_mismatch_assignment.carbon
+++ b/toolchain/check/testdata/operators/builtin/fail_type_mismatch_assignment.carbon
@@ -57,6 +57,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/fail_type_mismatch_once.carbon b/toolchain/check/testdata/operators/builtin/fail_type_mismatch_once.carbon
index 1fb5cbe04680..c16ec2d5a265 100644
--- a/toolchain/check/testdata/operators/builtin/fail_type_mismatch_once.carbon
+++ b/toolchain/check/testdata/operators/builtin/fail_type_mismatch_once.carbon
@@ -48,6 +48,7 @@ fn Main() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/fail_unimplemented_op.carbon b/toolchain/check/testdata/operators/builtin/fail_unimplemented_op.carbon
index ab40a157d635..698620e7a2cb 100644
--- a/toolchain/check/testdata/operators/builtin/fail_unimplemented_op.carbon
+++ b/toolchain/check/testdata/operators/builtin/fail_unimplemented_op.carbon
@@ -42,6 +42,7 @@ fn Main() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/or.carbon b/toolchain/check/testdata/operators/builtin/or.carbon
index 9fe2b05d3460..cc0018d86223 100644
--- a/toolchain/check/testdata/operators/builtin/or.carbon
+++ b/toolchain/check/testdata/operators/builtin/or.carbon
@@ -55,6 +55,7 @@ fn PartialConstant(x: bool) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/builtin/unary_op.carbon b/toolchain/check/testdata/operators/builtin/unary_op.carbon
index 26ba2f5e8e9a..b53bfd00739d 100644
--- a/toolchain/check/testdata/operators/builtin/unary_op.carbon
+++ b/toolchain/check/testdata/operators/builtin/unary_op.carbon
@@ -43,6 +43,7 @@ fn Constant() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/add.carbon b/toolchain/check/testdata/operators/overloaded/add.carbon
index 63d3961303fb..20d5bec1f910 100644
--- a/toolchain/check/testdata/operators/overloaded/add.carbon
+++ b/toolchain/check/testdata/operators/overloaded/add.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/bit_and.carbon b/toolchain/check/testdata/operators/overloaded/bit_and.carbon
index 4d72e88fe98c..d40789349c42 100644
--- a/toolchain/check/testdata/operators/overloaded/bit_and.carbon
+++ b/toolchain/check/testdata/operators/overloaded/bit_and.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/bit_complement.carbon b/toolchain/check/testdata/operators/overloaded/bit_complement.carbon
index 4bef6e43adbd..69708216e829 100644
--- a/toolchain/check/testdata/operators/overloaded/bit_complement.carbon
+++ b/toolchain/check/testdata/operators/overloaded/bit_complement.carbon
@@ -54,6 +54,7 @@ fn TestOp(a: C) -> C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/bit_or.carbon b/toolchain/check/testdata/operators/overloaded/bit_or.carbon
index dc59f15c08a4..72aed3746f7c 100644
--- a/toolchain/check/testdata/operators/overloaded/bit_or.carbon
+++ b/toolchain/check/testdata/operators/overloaded/bit_or.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/bit_xor.carbon b/toolchain/check/testdata/operators/overloaded/bit_xor.carbon
index f14f80f3c220..fda14e9f7135 100644
--- a/toolchain/check/testdata/operators/overloaded/bit_xor.carbon
+++ b/toolchain/check/testdata/operators/overloaded/bit_xor.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/dec.carbon b/toolchain/check/testdata/operators/overloaded/dec.carbon
index bf845553ef19..f71bffafc2e1 100644
--- a/toolchain/check/testdata/operators/overloaded/dec.carbon
+++ b/toolchain/check/testdata/operators/overloaded/dec.carbon
@@ -55,6 +55,7 @@ fn TestOp() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/div.carbon b/toolchain/check/testdata/operators/overloaded/div.carbon
index 1d3ac5933627..1017add6f151 100644
--- a/toolchain/check/testdata/operators/overloaded/div.carbon
+++ b/toolchain/check/testdata/operators/overloaded/div.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/eq.carbon b/toolchain/check/testdata/operators/overloaded/eq.carbon
index 36399d996db6..58154a1ce0b0 100644
--- a/toolchain/check/testdata/operators/overloaded/eq.carbon
+++ b/toolchain/check/testdata/operators/overloaded/eq.carbon
@@ -122,6 +122,7 @@ fn TestLhsBad(a: D, b: C) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -352,6 +353,7 @@ fn TestLhsBad(a: D, b: C) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -530,6 +532,7 @@ fn TestLhsBad(a: D, b: C) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/fail_assign_non_ref.carbon b/toolchain/check/testdata/operators/overloaded/fail_assign_non_ref.carbon
index cf160b7ce1f2..2459879eeb63 100644
--- a/toolchain/check/testdata/operators/overloaded/fail_assign_non_ref.carbon
+++ b/toolchain/check/testdata/operators/overloaded/fail_assign_non_ref.carbon
@@ -84,6 +84,7 @@ fn TestAddAssignNonRef(a: C, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/fail_no_impl.carbon b/toolchain/check/testdata/operators/overloaded/fail_no_impl.carbon
index b8645819e091..d93afdc19928 100644
--- a/toolchain/check/testdata/operators/overloaded/fail_no_impl.carbon
+++ b/toolchain/check/testdata/operators/overloaded/fail_no_impl.carbon
@@ -95,6 +95,7 @@ fn TestRef(b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/fail_no_impl_for_arg.carbon b/toolchain/check/testdata/operators/overloaded/fail_no_impl_for_arg.carbon
index d78dc9ac4b96..640e715b20e6 100644
--- a/toolchain/check/testdata/operators/overloaded/fail_no_impl_for_arg.carbon
+++ b/toolchain/check/testdata/operators/overloaded/fail_no_impl_for_arg.carbon
@@ -111,6 +111,7 @@ fn TestAssign(b: D) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/implicit_as.carbon b/toolchain/check/testdata/operators/overloaded/implicit_as.carbon
index 47c2e30353ea..53ff999e8ede 100644
--- a/toolchain/check/testdata/operators/overloaded/implicit_as.carbon
+++ b/toolchain/check/testdata/operators/overloaded/implicit_as.carbon
@@ -94,6 +94,7 @@ fn Test() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/inc.carbon b/toolchain/check/testdata/operators/overloaded/inc.carbon
index e75bcfe2d5f8..e1f5bf6efb03 100644
--- a/toolchain/check/testdata/operators/overloaded/inc.carbon
+++ b/toolchain/check/testdata/operators/overloaded/inc.carbon
@@ -55,6 +55,7 @@ fn TestOp() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/index.carbon b/toolchain/check/testdata/operators/overloaded/index.carbon
new file mode 100644
index 000000000000..8e70a847d299
--- /dev/null
+++ b/toolchain/check/testdata/operators/overloaded/index.carbon
@@ -0,0 +1,1053 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/operators/overloaded/index.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/operators/overloaded/index.carbon
+
+// --- overloaded_index.carbon
+
+library "[[@TEST_NAME]]";
+
+class C {}
+class ElementType {}
+class SubscriptType {}
+
+impl C as Core.IndexWith(SubscriptType, ElementType) {
+  fn At[self: Self](subscript: SubscriptType) -> ElementType {
+    return {};
+  }
+}
+
+let s: SubscriptType = {};
+let c: C = {};
+let x: ElementType = c[s];
+
+// --- overloaded_builtin.carbon
+
+library "[[@TEST_NAME]]";
+
+impl (i32, i32) as Core.IndexWith(i32, i32) {
+  fn At[self: Self](subscript: i32) -> i32 {
+    return self.0;
+  }
+}
+
+let s: (i32, i32) = (1, 5);
+let e: i32 = s[0];
+
+// --- fail_invalid_subscript_type.carbon
+
+library "[[@TEST_NAME]]";
+
+class C { }
+class ElementType {}
+class SubscriptType {}
+
+impl C as Core.IndexWith(SubscriptType, ElementType) {
+  fn At[self: Self](subscript: SubscriptType) -> ElementType {
+    return {};
+  }
+}
+
+let c: C = {};
+// CHECK:STDERR: fail_invalid_subscript_type.carbon:[[@LINE+7]]:22: error: cannot implicitly convert from `i32` to `SubscriptType` [ImplicitAsConversionFailure]
+// CHECK:STDERR: let x: ElementType = c[0];
+// CHECK:STDERR:                      ^~~~
+// CHECK:STDERR: fail_invalid_subscript_type.carbon:[[@LINE+4]]:22: note: type `i32` does not implement interface `ImplicitAs` [MissingImplInMemberAccessNote]
+// CHECK:STDERR: let x: ElementType = c[0];
+// CHECK:STDERR:                      ^~~~
+// CHECK:STDERR:
+let x: ElementType = c[0];
+
+// --- fail_index_with_not_implemented.carbon
+
+library "[[@TEST_NAME]]";
+
+class C { }
+
+let c: C = {};
+// CHECK:STDERR: fail_index_with_not_implemented.carbon:[[@LINE+3]]:14: error: type `C` does not support indexing [TypeNotIndexable]
+// CHECK:STDERR: let x: i32 = c[0];
+// CHECK:STDERR:              ^~~~
+let x: i32 = c[0];
+
+
+// CHECK:STDOUT: --- overloaded_index.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %C: type = class_type @C [template]
+// CHECK:STDOUT:   %.1: type = struct_type {} [template]
+// CHECK:STDOUT:   %.2: <witness> = complete_type_witness %.1 [template]
+// CHECK:STDOUT:   %ElementType.1: type = class_type @ElementType [template]
+// CHECK:STDOUT:   %SubscriptType.1: type = class_type @SubscriptType [template]
+// CHECK:STDOUT:   %IndexWith.type.1: type = generic_interface_type @IndexWith [template]
+// CHECK:STDOUT:   %.3: type = tuple_type () [template]
+// CHECK:STDOUT:   %IndexWith: %IndexWith.type.1 = struct_value () [template]
+// CHECK:STDOUT:   %ElementType.2: type = bind_symbolic_name ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.2: type = bind_symbolic_name SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.2: type = interface_type @IndexWith, @IndexWith(%SubscriptType.2, %ElementType.2) [symbolic]
+// CHECK:STDOUT:   %Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2) = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %Self.2: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %At.type.1: type = fn_type @At.1, @IndexWith(%SubscriptType.2, %ElementType.2) [symbolic]
+// CHECK:STDOUT:   %At.1: %At.type.1 = struct_value () [symbolic]
+// CHECK:STDOUT:   %.4: type = assoc_entity_type %IndexWith.type.2, %At.type.1 [symbolic]
+// CHECK:STDOUT:   %.5: %.4 = assoc_entity element0, imports.%import_ref.5 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.3: type = interface_type @IndexWith, @IndexWith(%SubscriptType.1, %ElementType.1) [template]
+// CHECK:STDOUT:   %At.type.2: type = fn_type @At.2 [template]
+// CHECK:STDOUT:   %At.2: %At.type.2 = struct_value () [template]
+// CHECK:STDOUT:   %At.type.3: type = fn_type @At.1, @IndexWith(%SubscriptType.1, %ElementType.1) [template]
+// CHECK:STDOUT:   %At.3: %At.type.3 = struct_value () [template]
+// CHECK:STDOUT:   %.6: type = assoc_entity_type %IndexWith.type.3, %At.type.3 [template]
+// CHECK:STDOUT:   %.7: %.6 = assoc_entity element0, imports.%import_ref.5 [template]
+// CHECK:STDOUT:   %.8: <witness> = interface_witness (%At.2) [template]
+// CHECK:STDOUT:   %.9: type = ptr_type %.1 [template]
+// CHECK:STDOUT:   %struct.1: %ElementType.1 = struct_value () [template]
+// CHECK:STDOUT:   %struct.2: %SubscriptType.1 = struct_value () [template]
+// CHECK:STDOUT:   %struct.3: %C = struct_value () [template]
+// CHECK:STDOUT:   %.10: %.4 = assoc_entity element0, imports.%import_ref.6 [symbolic]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
+// CHECK:STDOUT:     .IndexWith = %import_ref.1
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/operators
+// CHECK:STDOUT:     import Core//prelude/types
+// CHECK:STDOUT:     import Core//prelude/operators/arithmetic
+// CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
+// CHECK:STDOUT:     import Core//prelude/operators/bitwise
+// CHECK:STDOUT:     import Core//prelude/operators/comparison
+// CHECK:STDOUT:     import Core//prelude/types/bool
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %import_ref.1: %IndexWith.type.1 = import_ref Core//prelude/operators/index, inst+13, loaded [template = constants.%IndexWith]
+// CHECK:STDOUT:   %import_ref.2 = import_ref Core//prelude/operators/index, inst+22, unloaded
+// CHECK:STDOUT:   %import_ref.3: @IndexWith.%.1 (%.4) = import_ref Core//prelude/operators/index, inst+50, loaded [symbolic = @IndexWith.%.2 (constants.%.10)]
+// CHECK:STDOUT:   %import_ref.4: @IndexWith.%At.type (%At.type.1) = import_ref Core//prelude/operators/index, inst+42, loaded [symbolic = @IndexWith.%At (constants.%At.1)]
+// CHECK:STDOUT:   %import_ref.5 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT:   %import_ref.6 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = imports.%Core
+// CHECK:STDOUT:     .C = %C.decl
+// CHECK:STDOUT:     .ElementType = %ElementType.decl
+// CHECK:STDOUT:     .SubscriptType = %SubscriptType.decl
+// CHECK:STDOUT:     .s = @__global_init.%s
+// CHECK:STDOUT:     .c = @__global_init.%c
+// CHECK:STDOUT:     .x = @__global_init.%x
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   %C.decl: type = class_decl @C [template = constants.%C] {} {}
+// CHECK:STDOUT:   %ElementType.decl: type = class_decl @ElementType [template = constants.%ElementType.1] {} {}
+// CHECK:STDOUT:   %SubscriptType.decl: type = class_decl @SubscriptType [template = constants.%SubscriptType.1] {} {}
+// CHECK:STDOUT:   impl_decl @impl [template] {} {
+// CHECK:STDOUT:     %C.ref: type = name_ref C, file.%C.decl [template = constants.%C]
+// CHECK:STDOUT:     %Core.ref: <namespace> = name_ref Core, imports.%Core [template = imports.%Core]
+// CHECK:STDOUT:     %IndexWith.ref: %IndexWith.type.1 = name_ref IndexWith, imports.%import_ref.1 [template = constants.%IndexWith]
+// CHECK:STDOUT:     %SubscriptType.ref: type = name_ref SubscriptType, file.%SubscriptType.decl [template = constants.%SubscriptType.1]
+// CHECK:STDOUT:     %ElementType.ref: type = name_ref ElementType, file.%ElementType.decl [template = constants.%ElementType.1]
+// CHECK:STDOUT:     %IndexWith.type: type = interface_type @IndexWith, @IndexWith(constants.%SubscriptType.1, constants.%ElementType.1) [template = constants.%IndexWith.type.3]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %SubscriptType.ref: type = name_ref SubscriptType, %SubscriptType.decl [template = constants.%SubscriptType.1]
+// CHECK:STDOUT:   %C.ref: type = name_ref C, %C.decl [template = constants.%C]
+// CHECK:STDOUT:   %ElementType.ref: type = name_ref ElementType, %ElementType.decl [template = constants.%ElementType.1]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic interface @IndexWith(constants.%SubscriptType.2: type, constants.%ElementType.2: type) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType.2)]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic = %SubscriptType.patt (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType.2)]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic = %ElementType.patt (constants.%ElementType.patt)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:   %At.type: type = fn_type @At.1, @IndexWith(%SubscriptType, %ElementType) [symbolic = %At.type (constants.%At.type.1)]
+// CHECK:STDOUT:   %At: @IndexWith.%At.type (%At.type.1) = struct_value () [symbolic = %At (constants.%At.1)]
+// CHECK:STDOUT:   %.1: type = assoc_entity_type @IndexWith.%IndexWith.type (%IndexWith.type.2), @IndexWith.%At.type (%At.type.1) [symbolic = %.1 (constants.%.4)]
+// CHECK:STDOUT:   %.2: @IndexWith.%.1 (%.4) = assoc_entity element0, imports.%import_ref.5 [symbolic = %.2 (constants.%.5)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   interface {
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = imports.%import_ref.2
+// CHECK:STDOUT:     .At = imports.%import_ref.3
+// CHECK:STDOUT:     witness = (imports.%import_ref.4)
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: impl @impl: %C.ref as %IndexWith.type {
+// CHECK:STDOUT:   %At.decl: %At.type.2 = fn_decl @At.2 [template = constants.%At.2] {
+// CHECK:STDOUT:     %self.patt: %C = binding_pattern self
+// CHECK:STDOUT:     %self.param_patt: %C = value_param_pattern %self.patt, runtime_param0
+// CHECK:STDOUT:     %subscript.patt: %SubscriptType.1 = binding_pattern subscript
+// CHECK:STDOUT:     %subscript.param_patt: %SubscriptType.1 = value_param_pattern %subscript.patt, runtime_param1
+// CHECK:STDOUT:     %return.patt: %ElementType.1 = return_slot_pattern
+// CHECK:STDOUT:     %return.param_patt: %ElementType.1 = out_param_pattern %return.patt, runtime_param2
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %Self.ref: type = name_ref Self, @impl.%C.ref [template = constants.%C]
+// CHECK:STDOUT:     %SubscriptType.ref: type = name_ref SubscriptType, file.%SubscriptType.decl [template = constants.%SubscriptType.1]
+// CHECK:STDOUT:     %ElementType.ref: type = name_ref ElementType, file.%ElementType.decl [template = constants.%ElementType.1]
+// CHECK:STDOUT:     %self.param: %C = value_param runtime_param0
+// CHECK:STDOUT:     %self: %C = bind_name self, %self.param
+// CHECK:STDOUT:     %subscript.param: %SubscriptType.1 = value_param runtime_param1
+// CHECK:STDOUT:     %subscript: %SubscriptType.1 = bind_name subscript, %subscript.param
+// CHECK:STDOUT:     %return.param: ref %ElementType.1 = out_param runtime_param2
+// CHECK:STDOUT:     %return: ref %ElementType.1 = return_slot %return.param
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc8: <witness> = interface_witness (%At.decl) [template = constants.%.8]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .At = %At.decl
+// CHECK:STDOUT:   witness = %.loc8
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @C {
+// CHECK:STDOUT:   %.loc4: <witness> = complete_type_witness %.1 [template = constants.%.2]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%C
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @ElementType {
+// CHECK:STDOUT:   %.loc5: <witness> = complete_type_witness %.1 [template = constants.%.2]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%ElementType.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @SubscriptType {
+// CHECK:STDOUT:   %.loc6: <witness> = complete_type_witness %.1 [template = constants.%.2]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%SubscriptType.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @At.1(constants.%SubscriptType.2: type, constants.%ElementType.2: type, constants.%Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2)) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType.2)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType.2)]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn[%self.param_patt: @At.1.%Self (%Self.2)](%subscript.param_patt: @At.1.%SubscriptType (%SubscriptType.2)) -> @At.1.%ElementType (%ElementType.2);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @At.2[%self.param_patt: %C](%subscript.param_patt: %SubscriptType.1) -> %return: %ElementType.1 {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc10_13.1: %.1 = struct_literal ()
+// CHECK:STDOUT:   %.loc10_13.2: init %ElementType.1 = class_init (), %return [template = constants.%struct.1]
+// CHECK:STDOUT:   %.loc10_14: init %ElementType.1 = converted %.loc10_13.1, %.loc10_13.2 [template = constants.%struct.1]
+// CHECK:STDOUT:   return %.loc10_14 to %return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @__global_init() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc14_25.1: %.1 = struct_literal ()
+// CHECK:STDOUT:   %.loc14_25.2: ref %SubscriptType.1 = temporary_storage
+// CHECK:STDOUT:   %.loc14_25.3: init %SubscriptType.1 = class_init (), %.loc14_25.2 [template = constants.%struct.2]
+// CHECK:STDOUT:   %.loc14_25.4: ref %SubscriptType.1 = temporary %.loc14_25.2, %.loc14_25.3
+// CHECK:STDOUT:   %.loc14_26.1: ref %SubscriptType.1 = converted %.loc14_25.1, %.loc14_25.4
+// CHECK:STDOUT:   %.loc14_26.2: %SubscriptType.1 = bind_value %.loc14_26.1
+// CHECK:STDOUT:   %s: %SubscriptType.1 = bind_name s, %.loc14_26.2
+// CHECK:STDOUT:   %.loc15_13.1: %.1 = struct_literal ()
+// CHECK:STDOUT:   %.loc15_13.2: ref %C = temporary_storage
+// CHECK:STDOUT:   %.loc15_13.3: init %C = class_init (), %.loc15_13.2 [template = constants.%struct.3]
+// CHECK:STDOUT:   %.loc15_13.4: ref %C = temporary %.loc15_13.2, %.loc15_13.3
+// CHECK:STDOUT:   %.loc15_14.1: ref %C = converted %.loc15_13.1, %.loc15_13.4
+// CHECK:STDOUT:   %.loc15_14.2: %C = bind_value %.loc15_14.1
+// CHECK:STDOUT:   %c: %C = bind_name c, %.loc15_14.2
+// CHECK:STDOUT:   %c.ref: %C = name_ref c, %c
+// CHECK:STDOUT:   %s.ref: %SubscriptType.1 = name_ref s, %s
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(constants.%SubscriptType.1, constants.%ElementType.1) [template = constants.%IndexWith.type.3]
+// CHECK:STDOUT:   %.loc16_25.1: %.6 = specific_constant imports.%import_ref.3, @IndexWith(constants.%SubscriptType.1, constants.%ElementType.1) [template = constants.%.7]
+// CHECK:STDOUT:   %At.ref: %.6 = name_ref At, %.loc16_25.1 [template = constants.%.7]
+// CHECK:STDOUT:   %.loc16_25.2: %At.type.3 = interface_witness_access constants.%.8, element0 [template = constants.%At.2]
+// CHECK:STDOUT:   %.loc16_25.3: <bound method> = bound_method %c.ref, %.loc16_25.2
+// CHECK:STDOUT:   %.loc16_25.4: ref %ElementType.1 = temporary_storage
+// CHECK:STDOUT:   %At.call: init %ElementType.1 = call %.loc16_25.3(%c.ref, %s.ref) to %.loc16_25.4
+// CHECK:STDOUT:   %.loc16_25.5: ref %ElementType.1 = temporary %.loc16_25.4, %At.call
+// CHECK:STDOUT:   %.loc16_25.6: %ElementType.1 = bind_value %.loc16_25.5
+// CHECK:STDOUT:   %x: %ElementType.1 = bind_name x, %.loc16_25.6
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType.2, constants.%ElementType.2) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.2
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType.2
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.2
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType.2
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@IndexWith.%SubscriptType, @IndexWith.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.2
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType.2
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.2
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType.2
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@At.1.%SubscriptType, @At.1.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.2
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType.2
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.2
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType.2
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At.1(constants.%SubscriptType.2, constants.%ElementType.2, constants.%Self.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.2
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.2
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.2
+// CHECK:STDOUT:   %Self => constants.%Self.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType.1, constants.%ElementType.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.1
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType.1
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.1
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType.1
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.3
+// CHECK:STDOUT:   %Self => constants.%Self.2
+// CHECK:STDOUT:   %At.type => constants.%At.type.3
+// CHECK:STDOUT:   %At => constants.%At.3
+// CHECK:STDOUT:   %.1 => constants.%.6
+// CHECK:STDOUT:   %.2 => constants.%.7
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At.1(constants.%SubscriptType.1, constants.%ElementType.1, constants.%C) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.1
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.1
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.3
+// CHECK:STDOUT:   %Self => constants.%C
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- overloaded_builtin.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %Int32.type: type = fn_type @Int32 [template]
+// CHECK:STDOUT:   %.1: type = tuple_type () [template]
+// CHECK:STDOUT:   %Int32: %Int32.type = struct_value () [template]
+// CHECK:STDOUT:   %.2: type = tuple_type (type, type) [template]
+// CHECK:STDOUT:   %.3: type = tuple_type (i32, i32) [template]
+// CHECK:STDOUT:   %IndexWith.type.1: type = generic_interface_type @IndexWith [template]
+// CHECK:STDOUT:   %IndexWith: %IndexWith.type.1 = struct_value () [template]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.2: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2) = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %Self.2: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %At.type.1: type = fn_type @At.1, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %At.1: %At.type.1 = struct_value () [symbolic]
+// CHECK:STDOUT:   %.4: type = assoc_entity_type %IndexWith.type.2, %At.type.1 [symbolic]
+// CHECK:STDOUT:   %.5: %.4 = assoc_entity element0, imports.%import_ref.6 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.3: type = interface_type @IndexWith, @IndexWith(i32, i32) [template]
+// CHECK:STDOUT:   %At.type.2: type = fn_type @At.2 [template]
+// CHECK:STDOUT:   %At.2: %At.type.2 = struct_value () [template]
+// CHECK:STDOUT:   %At.type.3: type = fn_type @At.1, @IndexWith(i32, i32) [template]
+// CHECK:STDOUT:   %At.3: %At.type.3 = struct_value () [template]
+// CHECK:STDOUT:   %.6: type = assoc_entity_type %IndexWith.type.3, %At.type.3 [template]
+// CHECK:STDOUT:   %.7: %.6 = assoc_entity element0, imports.%import_ref.6 [template]
+// CHECK:STDOUT:   %.8: <witness> = interface_witness (%At.2) [template]
+// CHECK:STDOUT:   %.9: type = ptr_type %.3 [template]
+// CHECK:STDOUT:   %.10: i32 = int_literal 0 [template]
+// CHECK:STDOUT:   %.11: i32 = int_literal 1 [template]
+// CHECK:STDOUT:   %.12: i32 = int_literal 5 [template]
+// CHECK:STDOUT:   %tuple: %.3 = tuple_value (%.11, %.12) [template]
+// CHECK:STDOUT:   %.13: %.4 = assoc_entity element0, imports.%import_ref.7 [symbolic]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
+// CHECK:STDOUT:     .Int32 = %import_ref.1
+// CHECK:STDOUT:     .IndexWith = %import_ref.2
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/operators
+// CHECK:STDOUT:     import Core//prelude/types
+// CHECK:STDOUT:     import Core//prelude/operators/arithmetic
+// CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
+// CHECK:STDOUT:     import Core//prelude/operators/bitwise
+// CHECK:STDOUT:     import Core//prelude/operators/comparison
+// CHECK:STDOUT:     import Core//prelude/types/bool
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %import_ref.1: %Int32.type = import_ref Core//prelude/types, inst+15, loaded [template = constants.%Int32]
+// CHECK:STDOUT:   %import_ref.2: %IndexWith.type.1 = import_ref Core//prelude/operators/index, inst+13, loaded [template = constants.%IndexWith]
+// CHECK:STDOUT:   %import_ref.3 = import_ref Core//prelude/operators/index, inst+22, unloaded
+// CHECK:STDOUT:   %import_ref.4: @IndexWith.%.1 (%.4) = import_ref Core//prelude/operators/index, inst+50, loaded [symbolic = @IndexWith.%.2 (constants.%.13)]
+// CHECK:STDOUT:   %import_ref.5: @IndexWith.%At.type (%At.type.1) = import_ref Core//prelude/operators/index, inst+42, loaded [symbolic = @IndexWith.%At (constants.%At.1)]
+// CHECK:STDOUT:   %import_ref.6 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT:   %import_ref.7 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = imports.%Core
+// CHECK:STDOUT:     .s = @__global_init.%s
+// CHECK:STDOUT:     .e = @__global_init.%e
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   impl_decl @impl [template] {} {
+// CHECK:STDOUT:     %int.make_type_32.loc4_7: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:     %int.make_type_32.loc4_12: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:     %.loc4_15.1: %.2 = tuple_literal (%int.make_type_32.loc4_7, %int.make_type_32.loc4_12)
+// CHECK:STDOUT:     %.loc4_15.2: type = value_of_initializer %int.make_type_32.loc4_7 [template = i32]
+// CHECK:STDOUT:     %.loc4_15.3: type = converted %int.make_type_32.loc4_7, %.loc4_15.2 [template = i32]
+// CHECK:STDOUT:     %.loc4_15.4: type = value_of_initializer %int.make_type_32.loc4_12 [template = i32]
+// CHECK:STDOUT:     %.loc4_15.5: type = converted %int.make_type_32.loc4_12, %.loc4_15.4 [template = i32]
+// CHECK:STDOUT:     %.loc4_15.6: type = converted %.loc4_15.1, constants.%.3 [template = constants.%.3]
+// CHECK:STDOUT:     %Core.ref: <namespace> = name_ref Core, imports.%Core [template = imports.%Core]
+// CHECK:STDOUT:     %IndexWith.ref: %IndexWith.type.1 = name_ref IndexWith, imports.%import_ref.2 [template = constants.%IndexWith]
+// CHECK:STDOUT:     %int.make_type_32.loc4_35: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:     %int.make_type_32.loc4_40: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:     %.loc4_34.1: type = value_of_initializer %int.make_type_32.loc4_35 [template = i32]
+// CHECK:STDOUT:     %.loc4_34.2: type = converted %int.make_type_32.loc4_35, %.loc4_34.1 [template = i32]
+// CHECK:STDOUT:     %.loc4_34.3: type = value_of_initializer %int.make_type_32.loc4_40 [template = i32]
+// CHECK:STDOUT:     %.loc4_34.4: type = converted %int.make_type_32.loc4_40, %.loc4_34.3 [template = i32]
+// CHECK:STDOUT:     %IndexWith.type: type = interface_type @IndexWith, @IndexWith(i32, i32) [template = constants.%IndexWith.type.3]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %int.make_type_32.loc10_9: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:   %int.make_type_32.loc10_14: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:   %.loc10_17.1: %.2 = tuple_literal (%int.make_type_32.loc10_9, %int.make_type_32.loc10_14)
+// CHECK:STDOUT:   %.loc10_17.2: type = value_of_initializer %int.make_type_32.loc10_9 [template = i32]
+// CHECK:STDOUT:   %.loc10_17.3: type = converted %int.make_type_32.loc10_9, %.loc10_17.2 [template = i32]
+// CHECK:STDOUT:   %.loc10_17.4: type = value_of_initializer %int.make_type_32.loc10_14 [template = i32]
+// CHECK:STDOUT:   %.loc10_17.5: type = converted %int.make_type_32.loc10_14, %.loc10_17.4 [template = i32]
+// CHECK:STDOUT:   %.loc10_17.6: type = converted %.loc10_17.1, constants.%.3 [template = constants.%.3]
+// CHECK:STDOUT:   %int.make_type_32.loc11: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:   %.loc11_8.1: type = value_of_initializer %int.make_type_32.loc11 [template = i32]
+// CHECK:STDOUT:   %.loc11_8.2: type = converted %int.make_type_32.loc11, %.loc11_8.1 [template = i32]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic interface @IndexWith(constants.%SubscriptType: type, constants.%ElementType: type) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic = %SubscriptType.patt (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic = %ElementType.patt (constants.%ElementType.patt)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:   %At.type: type = fn_type @At.1, @IndexWith(%SubscriptType, %ElementType) [symbolic = %At.type (constants.%At.type.1)]
+// CHECK:STDOUT:   %At: @IndexWith.%At.type (%At.type.1) = struct_value () [symbolic = %At (constants.%At.1)]
+// CHECK:STDOUT:   %.1: type = assoc_entity_type @IndexWith.%IndexWith.type (%IndexWith.type.2), @IndexWith.%At.type (%At.type.1) [symbolic = %.1 (constants.%.4)]
+// CHECK:STDOUT:   %.2: @IndexWith.%.1 (%.4) = assoc_entity element0, imports.%import_ref.6 [symbolic = %.2 (constants.%.5)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   interface {
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = imports.%import_ref.3
+// CHECK:STDOUT:     .At = imports.%import_ref.4
+// CHECK:STDOUT:     witness = (imports.%import_ref.5)
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: impl @impl: %.loc4_15.6 as %IndexWith.type {
+// CHECK:STDOUT:   %At.decl: %At.type.2 = fn_decl @At.2 [template = constants.%At.2] {
+// CHECK:STDOUT:     %self.patt: %.3 = binding_pattern self
+// CHECK:STDOUT:     %self.param_patt: %.3 = value_param_pattern %self.patt, runtime_param0
+// CHECK:STDOUT:     %subscript.patt: i32 = binding_pattern subscript
+// CHECK:STDOUT:     %subscript.param_patt: i32 = value_param_pattern %subscript.patt, runtime_param1
+// CHECK:STDOUT:     %return.patt: i32 = return_slot_pattern
+// CHECK:STDOUT:     %return.param_patt: i32 = out_param_pattern %return.patt, runtime_param2
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %Self.ref: type = name_ref Self, @impl.%.loc4_15.6 [template = constants.%.3]
+// CHECK:STDOUT:     %int.make_type_32.loc5_32: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:     %.loc5_32.1: type = value_of_initializer %int.make_type_32.loc5_32 [template = i32]
+// CHECK:STDOUT:     %.loc5_32.2: type = converted %int.make_type_32.loc5_32, %.loc5_32.1 [template = i32]
+// CHECK:STDOUT:     %int.make_type_32.loc5_40: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:     %.loc5_40.1: type = value_of_initializer %int.make_type_32.loc5_40 [template = i32]
+// CHECK:STDOUT:     %.loc5_40.2: type = converted %int.make_type_32.loc5_40, %.loc5_40.1 [template = i32]
+// CHECK:STDOUT:     %self.param: %.3 = value_param runtime_param0
+// CHECK:STDOUT:     %self: %.3 = bind_name self, %self.param
+// CHECK:STDOUT:     %subscript.param: i32 = value_param runtime_param1
+// CHECK:STDOUT:     %subscript: i32 = bind_name subscript, %subscript.param
+// CHECK:STDOUT:     %return.param: ref i32 = out_param runtime_param2
+// CHECK:STDOUT:     %return: ref i32 = return_slot %return.param
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc4_45: <witness> = interface_witness (%At.decl) [template = constants.%.8]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .At = %At.decl
+// CHECK:STDOUT:   witness = %.loc4_45
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @Int32() -> type = "int.make_type_32";
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @At.1(constants.%SubscriptType: type, constants.%ElementType: type, constants.%Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2)) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn[%self.param_patt: @At.1.%Self (%Self.2)](%subscript.param_patt: @At.1.%SubscriptType (%SubscriptType)) -> @At.1.%ElementType (%ElementType);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @At.2[%self.param_patt: %.3](%subscript.param_patt: i32) -> i32 {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %self.ref: %.3 = name_ref self, %self
+// CHECK:STDOUT:   %.loc6_17: i32 = int_literal 0 [template = constants.%.10]
+// CHECK:STDOUT:   %.loc6_16: i32 = tuple_access %self.ref, element0
+// CHECK:STDOUT:   return %.loc6_16
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @__global_init() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc10_22: i32 = int_literal 1 [template = constants.%.11]
+// CHECK:STDOUT:   %.loc10_25: i32 = int_literal 5 [template = constants.%.12]
+// CHECK:STDOUT:   %.loc10_26: %.3 = tuple_literal (%.loc10_22, %.loc10_25)
+// CHECK:STDOUT:   %tuple: %.3 = tuple_value (%.loc10_22, %.loc10_25) [template = constants.%tuple]
+// CHECK:STDOUT:   %.loc10_27: %.3 = converted %.loc10_26, %tuple [template = constants.%tuple]
+// CHECK:STDOUT:   %s: %.3 = bind_name s, %.loc10_27
+// CHECK:STDOUT:   %s.ref: %.3 = name_ref s, %s
+// CHECK:STDOUT:   %.loc11_16: i32 = int_literal 0 [template = constants.%.10]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(i32, i32) [template = constants.%IndexWith.type.3]
+// CHECK:STDOUT:   %.loc11_17.1: %.6 = specific_constant imports.%import_ref.4, @IndexWith(i32, i32) [template = constants.%.7]
+// CHECK:STDOUT:   %At.ref: %.6 = name_ref At, %.loc11_17.1 [template = constants.%.7]
+// CHECK:STDOUT:   %.loc11_17.2: %At.type.3 = interface_witness_access constants.%.8, element0 [template = constants.%At.2]
+// CHECK:STDOUT:   %.loc11_17.3: <bound method> = bound_method %s.ref, %.loc11_17.2
+// CHECK:STDOUT:   %At.call: init i32 = call %.loc11_17.3(%s.ref, %.loc11_16)
+// CHECK:STDOUT:   %.loc11_18.1: i32 = value_of_initializer %At.call
+// CHECK:STDOUT:   %.loc11_18.2: i32 = converted %At.call, %.loc11_18.1
+// CHECK:STDOUT:   %e: i32 = bind_name e, %.loc11_18.2
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType, constants.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@IndexWith.%SubscriptType, @IndexWith.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@At.1.%SubscriptType, @At.1.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At.1(constants.%SubscriptType, constants.%ElementType, constants.%Self.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.2
+// CHECK:STDOUT:   %Self => constants.%Self.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(i32, i32) {
+// CHECK:STDOUT:   %SubscriptType => i32
+// CHECK:STDOUT:   %SubscriptType.patt => i32
+// CHECK:STDOUT:   %ElementType => i32
+// CHECK:STDOUT:   %ElementType.patt => i32
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.3
+// CHECK:STDOUT:   %Self => constants.%Self.2
+// CHECK:STDOUT:   %At.type => constants.%At.type.3
+// CHECK:STDOUT:   %At => constants.%At.3
+// CHECK:STDOUT:   %.1 => constants.%.6
+// CHECK:STDOUT:   %.2 => constants.%.7
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At.1(i32, i32, constants.%.3) {
+// CHECK:STDOUT:   %SubscriptType => i32
+// CHECK:STDOUT:   %ElementType => i32
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.3
+// CHECK:STDOUT:   %Self => constants.%.3
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_invalid_subscript_type.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %C: type = class_type @C [template]
+// CHECK:STDOUT:   %.1: type = struct_type {} [template]
+// CHECK:STDOUT:   %.2: <witness> = complete_type_witness %.1 [template]
+// CHECK:STDOUT:   %ElementType.1: type = class_type @ElementType [template]
+// CHECK:STDOUT:   %SubscriptType.1: type = class_type @SubscriptType [template]
+// CHECK:STDOUT:   %IndexWith.type.1: type = generic_interface_type @IndexWith [template]
+// CHECK:STDOUT:   %.3: type = tuple_type () [template]
+// CHECK:STDOUT:   %IndexWith: %IndexWith.type.1 = struct_value () [template]
+// CHECK:STDOUT:   %ElementType.2: type = bind_symbolic_name ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.2: type = bind_symbolic_name SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.2: type = interface_type @IndexWith, @IndexWith(%SubscriptType.2, %ElementType.2) [symbolic]
+// CHECK:STDOUT:   %Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2) = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %Self.2: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %At.type.1: type = fn_type @At.1, @IndexWith(%SubscriptType.2, %ElementType.2) [symbolic]
+// CHECK:STDOUT:   %At.1: %At.type.1 = struct_value () [symbolic]
+// CHECK:STDOUT:   %.4: type = assoc_entity_type %IndexWith.type.2, %At.type.1 [symbolic]
+// CHECK:STDOUT:   %.5: %.4 = assoc_entity element0, imports.%import_ref.5 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.3: type = interface_type @IndexWith, @IndexWith(%SubscriptType.1, %ElementType.1) [template]
+// CHECK:STDOUT:   %At.type.2: type = fn_type @At.2 [template]
+// CHECK:STDOUT:   %At.2: %At.type.2 = struct_value () [template]
+// CHECK:STDOUT:   %At.type.3: type = fn_type @At.1, @IndexWith(%SubscriptType.1, %ElementType.1) [template]
+// CHECK:STDOUT:   %At.3: %At.type.3 = struct_value () [template]
+// CHECK:STDOUT:   %.6: type = assoc_entity_type %IndexWith.type.3, %At.type.3 [template]
+// CHECK:STDOUT:   %.7: %.6 = assoc_entity element0, imports.%import_ref.5 [template]
+// CHECK:STDOUT:   %.8: <witness> = interface_witness (%At.2) [template]
+// CHECK:STDOUT:   %.9: type = ptr_type %.1 [template]
+// CHECK:STDOUT:   %struct.1: %ElementType.1 = struct_value () [template]
+// CHECK:STDOUT:   %struct.2: %C = struct_value () [template]
+// CHECK:STDOUT:   %.10: i32 = int_literal 0 [template]
+// CHECK:STDOUT:   %ImplicitAs.type.1: type = generic_interface_type @ImplicitAs [template]
+// CHECK:STDOUT:   %ImplicitAs: %ImplicitAs.type.1 = struct_value () [template]
+// CHECK:STDOUT:   %Dest: type = bind_symbolic_name Dest, 0 [symbolic]
+// CHECK:STDOUT:   %ImplicitAs.type.2: type = interface_type @ImplicitAs, @ImplicitAs(%Dest) [symbolic]
+// CHECK:STDOUT:   %Self.3: @ImplicitAs.%ImplicitAs.type (%ImplicitAs.type.2) = bind_symbolic_name Self, 1 [symbolic]
+// CHECK:STDOUT:   %Dest.patt: type = symbolic_binding_pattern Dest, 0 [symbolic]
+// CHECK:STDOUT:   %Self.4: %ImplicitAs.type.2 = bind_symbolic_name Self, 1 [symbolic]
+// CHECK:STDOUT:   %Convert.type.1: type = fn_type @Convert, @ImplicitAs(%Dest) [symbolic]
+// CHECK:STDOUT:   %Convert.1: %Convert.type.1 = struct_value () [symbolic]
+// CHECK:STDOUT:   %.11: type = assoc_entity_type %ImplicitAs.type.2, %Convert.type.1 [symbolic]
+// CHECK:STDOUT:   %.12: %.11 = assoc_entity element0, imports.%import_ref.10 [symbolic]
+// CHECK:STDOUT:   %ImplicitAs.type.3: type = interface_type @ImplicitAs, @ImplicitAs(%SubscriptType.1) [template]
+// CHECK:STDOUT:   %Convert.type.2: type = fn_type @Convert, @ImplicitAs(%SubscriptType.1) [template]
+// CHECK:STDOUT:   %Convert.2: %Convert.type.2 = struct_value () [template]
+// CHECK:STDOUT:   %.13: type = assoc_entity_type %ImplicitAs.type.3, %Convert.type.2 [template]
+// CHECK:STDOUT:   %.14: %.13 = assoc_entity element0, imports.%import_ref.10 [template]
+// CHECK:STDOUT:   %.15: %.11 = assoc_entity element0, imports.%import_ref.11 [symbolic]
+// CHECK:STDOUT:   %.16: %.4 = assoc_entity element0, imports.%import_ref.12 [symbolic]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
+// CHECK:STDOUT:     .IndexWith = %import_ref.1
+// CHECK:STDOUT:     .ImplicitAs = %import_ref.6
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/operators
+// CHECK:STDOUT:     import Core//prelude/types
+// CHECK:STDOUT:     import Core//prelude/operators/arithmetic
+// CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
+// CHECK:STDOUT:     import Core//prelude/operators/bitwise
+// CHECK:STDOUT:     import Core//prelude/operators/comparison
+// CHECK:STDOUT:     import Core//prelude/types/bool
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %import_ref.1: %IndexWith.type.1 = import_ref Core//prelude/operators/index, inst+13, loaded [template = constants.%IndexWith]
+// CHECK:STDOUT:   %import_ref.2 = import_ref Core//prelude/operators/index, inst+22, unloaded
+// CHECK:STDOUT:   %import_ref.3: @IndexWith.%.1 (%.4) = import_ref Core//prelude/operators/index, inst+50, loaded [symbolic = @IndexWith.%.2 (constants.%.16)]
+// CHECK:STDOUT:   %import_ref.4: @IndexWith.%At.type (%At.type.1) = import_ref Core//prelude/operators/index, inst+42, loaded [symbolic = @IndexWith.%At (constants.%At.1)]
+// CHECK:STDOUT:   %import_ref.5 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT:   %import_ref.6: %ImplicitAs.type.1 = import_ref Core//prelude/operators/as, inst+49, loaded [template = constants.%ImplicitAs]
+// CHECK:STDOUT:   %import_ref.7 = import_ref Core//prelude/operators/as, inst+55, unloaded
+// CHECK:STDOUT:   %import_ref.8: @ImplicitAs.%.1 (%.11) = import_ref Core//prelude/operators/as, inst+77, loaded [symbolic = @ImplicitAs.%.2 (constants.%.15)]
+// CHECK:STDOUT:   %import_ref.9 = import_ref Core//prelude/operators/as, inst+70, unloaded
+// CHECK:STDOUT:   %import_ref.10 = import_ref Core//prelude/operators/as, inst+70, unloaded
+// CHECK:STDOUT:   %import_ref.11 = import_ref Core//prelude/operators/as, inst+70, unloaded
+// CHECK:STDOUT:   %import_ref.12 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = imports.%Core
+// CHECK:STDOUT:     .C = %C.decl
+// CHECK:STDOUT:     .ElementType = %ElementType.decl
+// CHECK:STDOUT:     .SubscriptType = %SubscriptType.decl
+// CHECK:STDOUT:     .c = @__global_init.%c
+// CHECK:STDOUT:     .x = @__global_init.%x
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   %C.decl: type = class_decl @C [template = constants.%C] {} {}
+// CHECK:STDOUT:   %ElementType.decl: type = class_decl @ElementType [template = constants.%ElementType.1] {} {}
+// CHECK:STDOUT:   %SubscriptType.decl: type = class_decl @SubscriptType [template = constants.%SubscriptType.1] {} {}
+// CHECK:STDOUT:   impl_decl @impl [template] {} {
+// CHECK:STDOUT:     %C.ref: type = name_ref C, file.%C.decl [template = constants.%C]
+// CHECK:STDOUT:     %Core.ref: <namespace> = name_ref Core, imports.%Core [template = imports.%Core]
+// CHECK:STDOUT:     %IndexWith.ref: %IndexWith.type.1 = name_ref IndexWith, imports.%import_ref.1 [template = constants.%IndexWith]
+// CHECK:STDOUT:     %SubscriptType.ref: type = name_ref SubscriptType, file.%SubscriptType.decl [template = constants.%SubscriptType.1]
+// CHECK:STDOUT:     %ElementType.ref: type = name_ref ElementType, file.%ElementType.decl [template = constants.%ElementType.1]
+// CHECK:STDOUT:     %IndexWith.type: type = interface_type @IndexWith, @IndexWith(constants.%SubscriptType.1, constants.%ElementType.1) [template = constants.%IndexWith.type.3]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %C.ref: type = name_ref C, %C.decl [template = constants.%C]
+// CHECK:STDOUT:   %ElementType.ref: type = name_ref ElementType, %ElementType.decl [template = constants.%ElementType.1]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic interface @IndexWith(constants.%SubscriptType.2: type, constants.%ElementType.2: type) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType.2)]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic = %SubscriptType.patt (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType.2)]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic = %ElementType.patt (constants.%ElementType.patt)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:   %At.type: type = fn_type @At.1, @IndexWith(%SubscriptType, %ElementType) [symbolic = %At.type (constants.%At.type.1)]
+// CHECK:STDOUT:   %At: @IndexWith.%At.type (%At.type.1) = struct_value () [symbolic = %At (constants.%At.1)]
+// CHECK:STDOUT:   %.1: type = assoc_entity_type @IndexWith.%IndexWith.type (%IndexWith.type.2), @IndexWith.%At.type (%At.type.1) [symbolic = %.1 (constants.%.4)]
+// CHECK:STDOUT:   %.2: @IndexWith.%.1 (%.4) = assoc_entity element0, imports.%import_ref.5 [symbolic = %.2 (constants.%.5)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   interface {
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = imports.%import_ref.2
+// CHECK:STDOUT:     .At = imports.%import_ref.3
+// CHECK:STDOUT:     witness = (imports.%import_ref.4)
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic interface @ImplicitAs(constants.%Dest: type) {
+// CHECK:STDOUT:   %Dest: type = bind_symbolic_name Dest, 0 [symbolic = %Dest (constants.%Dest)]
+// CHECK:STDOUT:   %Dest.patt: type = symbolic_binding_pattern Dest, 0 [symbolic = %Dest.patt (constants.%Dest.patt)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %ImplicitAs.type: type = interface_type @ImplicitAs, @ImplicitAs(%Dest) [symbolic = %ImplicitAs.type (constants.%ImplicitAs.type.2)]
+// CHECK:STDOUT:   %Self: %ImplicitAs.type.2 = bind_symbolic_name Self, 1 [symbolic = %Self (constants.%Self.4)]
+// CHECK:STDOUT:   %Convert.type: type = fn_type @Convert, @ImplicitAs(%Dest) [symbolic = %Convert.type (constants.%Convert.type.1)]
+// CHECK:STDOUT:   %Convert: @ImplicitAs.%Convert.type (%Convert.type.1) = struct_value () [symbolic = %Convert (constants.%Convert.1)]
+// CHECK:STDOUT:   %.1: type = assoc_entity_type @ImplicitAs.%ImplicitAs.type (%ImplicitAs.type.2), @ImplicitAs.%Convert.type (%Convert.type.1) [symbolic = %.1 (constants.%.11)]
+// CHECK:STDOUT:   %.2: @ImplicitAs.%.1 (%.11) = assoc_entity element0, imports.%import_ref.10 [symbolic = %.2 (constants.%.12)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   interface {
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = imports.%import_ref.7
+// CHECK:STDOUT:     .Convert = imports.%import_ref.8
+// CHECK:STDOUT:     witness = (imports.%import_ref.9)
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: impl @impl: %C.ref as %IndexWith.type {
+// CHECK:STDOUT:   %At.decl: %At.type.2 = fn_decl @At.2 [template = constants.%At.2] {
+// CHECK:STDOUT:     %self.patt: %C = binding_pattern self
+// CHECK:STDOUT:     %self.param_patt: %C = value_param_pattern %self.patt, runtime_param0
+// CHECK:STDOUT:     %subscript.patt: %SubscriptType.1 = binding_pattern subscript
+// CHECK:STDOUT:     %subscript.param_patt: %SubscriptType.1 = value_param_pattern %subscript.patt, runtime_param1
+// CHECK:STDOUT:     %return.patt: %ElementType.1 = return_slot_pattern
+// CHECK:STDOUT:     %return.param_patt: %ElementType.1 = out_param_pattern %return.patt, runtime_param2
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %Self.ref: type = name_ref Self, @impl.%C.ref [template = constants.%C]
+// CHECK:STDOUT:     %SubscriptType.ref: type = name_ref SubscriptType, file.%SubscriptType.decl [template = constants.%SubscriptType.1]
+// CHECK:STDOUT:     %ElementType.ref: type = name_ref ElementType, file.%ElementType.decl [template = constants.%ElementType.1]
+// CHECK:STDOUT:     %self.param: %C = value_param runtime_param0
+// CHECK:STDOUT:     %self: %C = bind_name self, %self.param
+// CHECK:STDOUT:     %subscript.param: %SubscriptType.1 = value_param runtime_param1
+// CHECK:STDOUT:     %subscript: %SubscriptType.1 = bind_name subscript, %subscript.param
+// CHECK:STDOUT:     %return.param: ref %ElementType.1 = out_param runtime_param2
+// CHECK:STDOUT:     %return: ref %ElementType.1 = return_slot %return.param
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc8: <witness> = interface_witness (%At.decl) [template = constants.%.8]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .At = %At.decl
+// CHECK:STDOUT:   witness = %.loc8
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @C {
+// CHECK:STDOUT:   %.loc4: <witness> = complete_type_witness %.1 [template = constants.%.2]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%C
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @ElementType {
+// CHECK:STDOUT:   %.loc5: <witness> = complete_type_witness %.1 [template = constants.%.2]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%ElementType.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @SubscriptType {
+// CHECK:STDOUT:   %.loc6: <witness> = complete_type_witness %.1 [template = constants.%.2]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%SubscriptType.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @At.1(constants.%SubscriptType.2: type, constants.%ElementType.2: type, constants.%Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2)) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType.2)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType.2)]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn[%self.param_patt: @At.1.%Self (%Self.2)](%subscript.param_patt: @At.1.%SubscriptType (%SubscriptType.2)) -> @At.1.%ElementType (%ElementType.2);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @At.2[%self.param_patt: %C](%subscript.param_patt: %SubscriptType.1) -> %return: %ElementType.1 {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc10_13.1: %.1 = struct_literal ()
+// CHECK:STDOUT:   %.loc10_13.2: init %ElementType.1 = class_init (), %return [template = constants.%struct.1]
+// CHECK:STDOUT:   %.loc10_14: init %ElementType.1 = converted %.loc10_13.1, %.loc10_13.2 [template = constants.%struct.1]
+// CHECK:STDOUT:   return %.loc10_14 to %return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @Convert(constants.%Dest: type, constants.%Self.3: @ImplicitAs.%ImplicitAs.type (%ImplicitAs.type.2)) {
+// CHECK:STDOUT:   %Dest: type = bind_symbolic_name Dest, 0 [symbolic = %Dest (constants.%Dest)]
+// CHECK:STDOUT:   %ImplicitAs.type: type = interface_type @ImplicitAs, @ImplicitAs(%Dest) [symbolic = %ImplicitAs.type (constants.%ImplicitAs.type.2)]
+// CHECK:STDOUT:   %Self: %ImplicitAs.type.2 = bind_symbolic_name Self, 1 [symbolic = %Self (constants.%Self.4)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn[%self.param_patt: @Convert.%Self (%Self.4)]() -> @Convert.%Dest (%Dest);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @__global_init() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc14_13.1: %.1 = struct_literal ()
+// CHECK:STDOUT:   %.loc14_13.2: ref %C = temporary_storage
+// CHECK:STDOUT:   %.loc14_13.3: init %C = class_init (), %.loc14_13.2 [template = constants.%struct.2]
+// CHECK:STDOUT:   %.loc14_13.4: ref %C = temporary %.loc14_13.2, %.loc14_13.3
+// CHECK:STDOUT:   %.loc14_14.1: ref %C = converted %.loc14_13.1, %.loc14_13.4
+// CHECK:STDOUT:   %.loc14_14.2: %C = bind_value %.loc14_14.1
+// CHECK:STDOUT:   %c: %C = bind_name c, %.loc14_14.2
+// CHECK:STDOUT:   %c.ref: %C = name_ref c, %c
+// CHECK:STDOUT:   %.loc22_24: i32 = int_literal 0 [template = constants.%.10]
+// CHECK:STDOUT:   %ImplicitAs.type: type = interface_type @ImplicitAs, @ImplicitAs(constants.%SubscriptType.1) [template = constants.%ImplicitAs.type.3]
+// CHECK:STDOUT:   %.loc22_25.1: %.13 = specific_constant imports.%import_ref.8, @ImplicitAs(constants.%SubscriptType.1) [template = constants.%.14]
+// CHECK:STDOUT:   %Convert.ref: %.13 = name_ref Convert, %.loc22_25.1 [template = constants.%.14]
+// CHECK:STDOUT:   %.loc22_25.2: %SubscriptType.1 = converted %.loc22_24, <error> [template = <error>]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(constants.%SubscriptType.1, constants.%ElementType.1) [template = constants.%IndexWith.type.3]
+// CHECK:STDOUT:   %.loc22_25.3: %.6 = specific_constant imports.%import_ref.3, @IndexWith(constants.%SubscriptType.1, constants.%ElementType.1) [template = constants.%.7]
+// CHECK:STDOUT:   %At.ref: %.6 = name_ref At, %.loc22_25.3 [template = constants.%.7]
+// CHECK:STDOUT:   %.loc22_25.4: %At.type.3 = interface_witness_access constants.%.8, element0 [template = constants.%At.2]
+// CHECK:STDOUT:   %.loc22_25.5: <bound method> = bound_method %c.ref, %.loc22_25.4
+// CHECK:STDOUT:   %.loc22_25.6: ref %ElementType.1 = temporary_storage
+// CHECK:STDOUT:   %At.call: init %ElementType.1 = call %.loc22_25.5(<invalid>) [template = <error>]
+// CHECK:STDOUT:   %.loc22_25.7: ref %ElementType.1 = temporary_storage
+// CHECK:STDOUT:   %.loc22_25.8: ref %ElementType.1 = temporary %.loc22_25.7, %At.call
+// CHECK:STDOUT:   %.loc22_25.9: %ElementType.1 = bind_value %.loc22_25.8
+// CHECK:STDOUT:   %x: %ElementType.1 = bind_name x, %.loc22_25.9
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType.2, constants.%ElementType.2) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.2
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType.2
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.2
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType.2
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@IndexWith.%SubscriptType, @IndexWith.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.2
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType.2
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.2
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType.2
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@At.1.%SubscriptType, @At.1.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.2
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType.2
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.2
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType.2
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At.1(constants.%SubscriptType.2, constants.%ElementType.2, constants.%Self.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.2
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.2
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.2
+// CHECK:STDOUT:   %Self => constants.%Self.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType.1, constants.%ElementType.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.1
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType.1
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.1
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType.1
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.3
+// CHECK:STDOUT:   %Self => constants.%Self.2
+// CHECK:STDOUT:   %At.type => constants.%At.type.3
+// CHECK:STDOUT:   %At => constants.%At.3
+// CHECK:STDOUT:   %.1 => constants.%.6
+// CHECK:STDOUT:   %.2 => constants.%.7
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At.1(constants.%SubscriptType.1, constants.%ElementType.1, constants.%C) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType.1
+// CHECK:STDOUT:   %ElementType => constants.%ElementType.1
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.3
+// CHECK:STDOUT:   %Self => constants.%C
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @ImplicitAs(constants.%Dest) {
+// CHECK:STDOUT:   %Dest => constants.%Dest
+// CHECK:STDOUT:   %Dest.patt => constants.%Dest
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @ImplicitAs(@ImplicitAs.%Dest) {
+// CHECK:STDOUT:   %Dest => constants.%Dest
+// CHECK:STDOUT:   %Dest.patt => constants.%Dest
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @ImplicitAs(@Convert.%Dest) {
+// CHECK:STDOUT:   %Dest => constants.%Dest
+// CHECK:STDOUT:   %Dest.patt => constants.%Dest
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @Convert(constants.%Dest, constants.%Self.3) {
+// CHECK:STDOUT:   %Dest => constants.%Dest
+// CHECK:STDOUT:   %ImplicitAs.type => constants.%ImplicitAs.type.2
+// CHECK:STDOUT:   %Self => constants.%Self.3
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @ImplicitAs(constants.%SubscriptType.1) {
+// CHECK:STDOUT:   %Dest => constants.%SubscriptType.1
+// CHECK:STDOUT:   %Dest.patt => constants.%SubscriptType.1
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %ImplicitAs.type => constants.%ImplicitAs.type.3
+// CHECK:STDOUT:   %Self => constants.%Self.4
+// CHECK:STDOUT:   %Convert.type => constants.%Convert.type.2
+// CHECK:STDOUT:   %Convert => constants.%Convert.2
+// CHECK:STDOUT:   %.1 => constants.%.13
+// CHECK:STDOUT:   %.2 => constants.%.14
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_index_with_not_implemented.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %C: type = class_type @C [template]
+// CHECK:STDOUT:   %.1: type = struct_type {} [template]
+// CHECK:STDOUT:   %.2: <witness> = complete_type_witness %.1 [template]
+// CHECK:STDOUT:   %.3: type = tuple_type () [template]
+// CHECK:STDOUT:   %.4: type = ptr_type %.1 [template]
+// CHECK:STDOUT:   %struct: %C = struct_value () [template]
+// CHECK:STDOUT:   %Int32.type: type = fn_type @Int32 [template]
+// CHECK:STDOUT:   %Int32: %Int32.type = struct_value () [template]
+// CHECK:STDOUT:   %.5: i32 = int_literal 0 [template]
+// CHECK:STDOUT:   %IndexWith.type.1: type = generic_interface_type @IndexWith [template]
+// CHECK:STDOUT:   %IndexWith: %IndexWith.type.1 = struct_value () [template]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.2: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2) = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %Self.2: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %At.type: type = fn_type @At, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %At: %At.type = struct_value () [symbolic]
+// CHECK:STDOUT:   %.6: type = assoc_entity_type %IndexWith.type.2, %At.type [symbolic]
+// CHECK:STDOUT:   %.7: %.6 = assoc_entity element0, imports.%import_ref.6 [symbolic]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
+// CHECK:STDOUT:     .Int32 = %import_ref.1
+// CHECK:STDOUT:     .IndexWith = %import_ref.2
+// CHECK:STDOUT:     import Core//prelude
+// CHECK:STDOUT:     import Core//prelude/operators
+// CHECK:STDOUT:     import Core//prelude/types
+// CHECK:STDOUT:     import Core//prelude/operators/arithmetic
+// CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
+// CHECK:STDOUT:     import Core//prelude/operators/bitwise
+// CHECK:STDOUT:     import Core//prelude/operators/comparison
+// CHECK:STDOUT:     import Core//prelude/types/bool
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %import_ref.1: %Int32.type = import_ref Core//prelude/types, inst+15, loaded [template = constants.%Int32]
+// CHECK:STDOUT:   %import_ref.2: %IndexWith.type.1 = import_ref Core//prelude/operators/index, inst+13, loaded [template = constants.%IndexWith]
+// CHECK:STDOUT:   %import_ref.3 = import_ref Core//prelude/operators/index, inst+22, unloaded
+// CHECK:STDOUT:   %import_ref.4 = import_ref Core//prelude/operators/index, inst+50, unloaded
+// CHECK:STDOUT:   %import_ref.5 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT:   %import_ref.6 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = imports.%Core
+// CHECK:STDOUT:     .C = %C.decl
+// CHECK:STDOUT:     .c = @__global_init.%c
+// CHECK:STDOUT:     .x = @__global_init.%x
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import = import Core
+// CHECK:STDOUT:   %C.decl: type = class_decl @C [template = constants.%C] {} {}
+// CHECK:STDOUT:   %C.ref: type = name_ref C, %C.decl [template = constants.%C]
+// CHECK:STDOUT:   %int.make_type_32: init type = call constants.%Int32() [template = i32]
+// CHECK:STDOUT:   %.loc10_8.1: type = value_of_initializer %int.make_type_32 [template = i32]
+// CHECK:STDOUT:   %.loc10_8.2: type = converted %int.make_type_32, %.loc10_8.1 [template = i32]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic interface @IndexWith(constants.%SubscriptType: type, constants.%ElementType: type) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic = %SubscriptType.patt (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic = %ElementType.patt (constants.%ElementType.patt)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:   %At.type: type = fn_type @At, @IndexWith(%SubscriptType, %ElementType) [symbolic = %At.type (constants.%At.type)]
+// CHECK:STDOUT:   %At: @IndexWith.%At.type (%At.type) = struct_value () [symbolic = %At (constants.%At)]
+// CHECK:STDOUT:   %.1: type = assoc_entity_type @IndexWith.%IndexWith.type (%IndexWith.type.2), @IndexWith.%At.type (%At.type) [symbolic = %.1 (constants.%.6)]
+// CHECK:STDOUT:   %.2: @IndexWith.%.1 (%.6) = assoc_entity element0, imports.%import_ref.6 [symbolic = %.2 (constants.%.7)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   interface {
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = imports.%import_ref.3
+// CHECK:STDOUT:     .At = imports.%import_ref.4
+// CHECK:STDOUT:     witness = (imports.%import_ref.5)
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @C {
+// CHECK:STDOUT:   %.loc4: <witness> = complete_type_witness %.1 [template = constants.%.2]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%C
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @Int32() -> type = "int.make_type_32";
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @At(constants.%SubscriptType: type, constants.%ElementType: type, constants.%Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2)) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn[%self.param_patt: @At.%Self (%Self.2)](%subscript.param_patt: @At.%SubscriptType (%SubscriptType)) -> @At.%ElementType (%ElementType);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @__global_init() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc6_13.1: %.1 = struct_literal ()
+// CHECK:STDOUT:   %.loc6_13.2: ref %C = temporary_storage
+// CHECK:STDOUT:   %.loc6_13.3: init %C = class_init (), %.loc6_13.2 [template = constants.%struct]
+// CHECK:STDOUT:   %.loc6_13.4: ref %C = temporary %.loc6_13.2, %.loc6_13.3
+// CHECK:STDOUT:   %.loc6_14.1: ref %C = converted %.loc6_13.1, %.loc6_13.4
+// CHECK:STDOUT:   %.loc6_14.2: %C = bind_value %.loc6_14.1
+// CHECK:STDOUT:   %c: %C = bind_name c, %.loc6_14.2
+// CHECK:STDOUT:   %c.ref: %C = name_ref c, %c
+// CHECK:STDOUT:   %.loc10: i32 = int_literal 0 [template = constants.%.5]
+// CHECK:STDOUT:   %x: i32 = bind_name x, <error>
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType, constants.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@IndexWith.%SubscriptType, @IndexWith.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@At.%SubscriptType, @At.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At(constants.%SubscriptType, constants.%ElementType, constants.%Self.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.2
+// CHECK:STDOUT:   %Self => constants.%Self.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
diff --git a/toolchain/check/testdata/operators/overloaded/left_shift.carbon b/toolchain/check/testdata/operators/overloaded/left_shift.carbon
index 19e6544379bb..8a07d2b0c4b6 100644
--- a/toolchain/check/testdata/operators/overloaded/left_shift.carbon
+++ b/toolchain/check/testdata/operators/overloaded/left_shift.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/mod.carbon b/toolchain/check/testdata/operators/overloaded/mod.carbon
index 57f6879f4c74..780cb7bbe1df 100644
--- a/toolchain/check/testdata/operators/overloaded/mod.carbon
+++ b/toolchain/check/testdata/operators/overloaded/mod.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/mul.carbon b/toolchain/check/testdata/operators/overloaded/mul.carbon
index 6998d87c5ee2..d1bde84121c6 100644
--- a/toolchain/check/testdata/operators/overloaded/mul.carbon
+++ b/toolchain/check/testdata/operators/overloaded/mul.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/negate.carbon b/toolchain/check/testdata/operators/overloaded/negate.carbon
index c91cada978ee..623f469c548c 100644
--- a/toolchain/check/testdata/operators/overloaded/negate.carbon
+++ b/toolchain/check/testdata/operators/overloaded/negate.carbon
@@ -54,6 +54,7 @@ fn TestOp(a: C) -> C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/no_prelude/index.carbon b/toolchain/check/testdata/operators/overloaded/no_prelude/index.carbon
new file mode 100644
index 000000000000..feda6ff13601
--- /dev/null
+++ b/toolchain/check/testdata/operators/overloaded/no_prelude/index.carbon
@@ -0,0 +1,316 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/operators/overloaded/no_prelude/index.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/operators/overloaded/no_prelude/index.carbon
+
+// --- fail_wrong_index_with.carbon
+
+library "[[@TEST_NAME]]";
+
+namespace Core;
+class Core.IndexWith {}
+// CHECK:STDERR: fail_wrong_index_with.carbon:[[@LINE+4]]:10: error: type `i32` does not support indexing [TypeNotIndexable]
+// CHECK:STDERR: fn F() { 0[1]; }
+// CHECK:STDERR:          ^~~~
+// CHECK:STDERR:
+fn F() { 0[1]; }
+
+// --- fail_missing_index_with.carbon
+
+library "[[@TEST_NAME]]";
+
+// CHECK:STDERR: fail_missing_index_with.carbon:[[@LINE+7]]:10: error: package `Core` implicitly referenced here, but not found [CoreNotFound]
+// CHECK:STDERR: fn F() { 0[1]; }
+// CHECK:STDERR:          ^~~~
+// CHECK:STDERR:
+// CHECK:STDERR: fail_missing_index_with.carbon:[[@LINE+3]]:10: error: type `i32` does not support indexing [TypeNotIndexable]
+// CHECK:STDERR: fn F() { 0[1]; }
+// CHECK:STDERR:          ^~~~
+fn F() { 0[1]; }
+
+// --- wrong_arg_count.carbon
+
+library "[[@TEST_NAME]]";
+
+namespace Core;
+interface Core.IndexWith(SubscriptType:! type) {
+  fn At[self: Self](subscript: SubscriptType) -> ();
+}
+
+impl () as Core.IndexWith(()) {
+  fn At[self: Self](subscript: ()) -> () {
+    return ();
+  }
+}
+
+fn F() { ()[()]; }
+
+// CHECK:STDOUT: --- fail_wrong_index_with.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %IndexWith: type = class_type @IndexWith [template]
+// CHECK:STDOUT:   %.1: type = struct_type {} [template]
+// CHECK:STDOUT:   %.2: <witness> = complete_type_witness %.1 [template]
+// CHECK:STDOUT:   %F.type: type = fn_type @F [template]
+// CHECK:STDOUT:   %.3: type = tuple_type () [template]
+// CHECK:STDOUT:   %F: %F.type = struct_value () [template]
+// CHECK:STDOUT:   %.4: i32 = int_literal 0 [template]
+// CHECK:STDOUT:   %.5: i32 = int_literal 1 [template]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = %Core
+// CHECK:STDOUT:     .F = %F.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .IndexWith = %IndexWith.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %IndexWith.decl: type = class_decl @IndexWith [template = constants.%IndexWith] {} {}
+// CHECK:STDOUT:   %F.decl: %F.type = fn_decl @F [template = constants.%F] {} {}
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: class @IndexWith {
+// CHECK:STDOUT:   %.loc5: <witness> = complete_type_witness %.1 [template = constants.%.2]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .Self = constants.%IndexWith
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc10_10: i32 = int_literal 0 [template = constants.%.4]
+// CHECK:STDOUT:   %.loc10_12: i32 = int_literal 1 [template = constants.%.5]
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_missing_index_with.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %F.type: type = fn_type @F [template]
+// CHECK:STDOUT:   %.1: type = tuple_type () [template]
+// CHECK:STDOUT:   %F: %F.type = struct_value () [template]
+// CHECK:STDOUT:   %.2: i32 = int_literal 0 [template]
+// CHECK:STDOUT:   %.3: i32 = int_literal 1 [template]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .F = %F.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %F.decl: %F.type = fn_decl @F [template = constants.%F] {} {}
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc11_10: i32 = int_literal 0 [template = constants.%.2]
+// CHECK:STDOUT:   %.loc11_12: i32 = int_literal 1 [template = constants.%.3]
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- wrong_arg_count.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.1: type = generic_interface_type @IndexWith [template]
+// CHECK:STDOUT:   %.1: type = tuple_type () [template]
+// CHECK:STDOUT:   %IndexWith: %IndexWith.type.1 = struct_value () [template]
+// CHECK:STDOUT:   %IndexWith.type.2: type = interface_type @IndexWith, @IndexWith(%SubscriptType) [symbolic]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 1 [symbolic]
+// CHECK:STDOUT:   %At.type.1: type = fn_type @At.1, @IndexWith(%SubscriptType) [symbolic]
+// CHECK:STDOUT:   %At.1: %At.type.1 = struct_value () [symbolic]
+// CHECK:STDOUT:   %.2: type = assoc_entity_type %IndexWith.type.2, %At.type.1 [symbolic]
+// CHECK:STDOUT:   %.3: %.2 = assoc_entity element0, @IndexWith.%At.decl [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.3: type = interface_type @IndexWith, @IndexWith(%.1) [template]
+// CHECK:STDOUT:   %At.type.2: type = fn_type @At.2 [template]
+// CHECK:STDOUT:   %At.2: %At.type.2 = struct_value () [template]
+// CHECK:STDOUT:   %At.type.3: type = fn_type @At.1, @IndexWith(%.1) [template]
+// CHECK:STDOUT:   %At.3: %At.type.3 = struct_value () [template]
+// CHECK:STDOUT:   %.4: type = assoc_entity_type %IndexWith.type.3, %At.type.3 [template]
+// CHECK:STDOUT:   %.5: %.4 = assoc_entity element0, @IndexWith.%At.decl [template]
+// CHECK:STDOUT:   %.6: <witness> = interface_witness (%At.2) [template]
+// CHECK:STDOUT:   %tuple: %.1 = tuple_value () [template]
+// CHECK:STDOUT:   %F.type: type = fn_type @F [template]
+// CHECK:STDOUT:   %F: %F.type = struct_value () [template]
+// CHECK:STDOUT:   %.7: <bound method> = bound_method %tuple, %At.2 [template]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   package: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .Core = %Core
+// CHECK:STDOUT:     .F = %F.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core: <namespace> = namespace [template] {
+// CHECK:STDOUT:     .IndexWith = %IndexWith.decl
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %IndexWith.decl: %IndexWith.type.1 = interface_decl @IndexWith [template = constants.%IndexWith] {
+// CHECK:STDOUT:     %SubscriptType.patt.loc5_26.1: type = symbolic_binding_pattern SubscriptType, 0 [symbolic = %SubscriptType.patt.loc5_26.2 (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:     %SubscriptType.param_patt: type = value_param_pattern %SubscriptType.patt.loc5_26.1, runtime_param<invalid> [symbolic = %SubscriptType.patt.loc5_26.2 (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %SubscriptType.param: type = value_param runtime_param<invalid>
+// CHECK:STDOUT:     %SubscriptType.loc5_26.1: type = bind_symbolic_name SubscriptType, 0, %SubscriptType.param [symbolic = %SubscriptType.loc5_26.2 (constants.%SubscriptType)]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   impl_decl @impl [template] {} {
+// CHECK:STDOUT:     %.loc9_7.1: %.1 = tuple_literal ()
+// CHECK:STDOUT:     %.loc9_7.2: type = converted %.loc9_7.1, constants.%.1 [template = constants.%.1]
+// CHECK:STDOUT:     %Core.ref: <namespace> = name_ref Core, file.%Core [template = file.%Core]
+// CHECK:STDOUT:     %IndexWith.ref: %IndexWith.type.1 = name_ref IndexWith, file.%IndexWith.decl [template = constants.%IndexWith]
+// CHECK:STDOUT:     %.loc9_28: %.1 = tuple_literal ()
+// CHECK:STDOUT:     %.loc9_26: type = converted %.loc9_28, constants.%.1 [template = constants.%.1]
+// CHECK:STDOUT:     %IndexWith.type: type = interface_type @IndexWith, @IndexWith(constants.%.1) [template = constants.%IndexWith.type.3]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %F.decl: %F.type = fn_decl @F [template = constants.%F] {} {}
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic interface @IndexWith(%SubscriptType.loc5_26.1: type) {
+// CHECK:STDOUT:   %SubscriptType.loc5_26.2: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType.loc5_26.2 (constants.%SubscriptType)]
+// CHECK:STDOUT:   %SubscriptType.patt.loc5_26.2: type = symbolic_binding_pattern SubscriptType, 0 [symbolic = %SubscriptType.patt.loc5_26.2 (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType.loc5_26.2) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self.2: %IndexWith.type.2 = bind_symbolic_name Self, 1 [symbolic = %Self.2 (constants.%Self)]
+// CHECK:STDOUT:   %At.type: type = fn_type @At.1, @IndexWith(%SubscriptType.loc5_26.2) [symbolic = %At.type (constants.%At.type.1)]
+// CHECK:STDOUT:   %At: @IndexWith.%At.type (%At.type.1) = struct_value () [symbolic = %At (constants.%At.1)]
+// CHECK:STDOUT:   %.loc6_52.2: type = assoc_entity_type @IndexWith.%IndexWith.type (%IndexWith.type.2), @IndexWith.%At.type (%At.type.1) [symbolic = %.loc6_52.2 (constants.%.2)]
+// CHECK:STDOUT:   %.loc6_52.3: @IndexWith.%.loc6_52.2 (%.2) = assoc_entity element0, %At.decl [symbolic = %.loc6_52.3 (constants.%.3)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   interface {
+// CHECK:STDOUT:     %Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2) = bind_symbolic_name Self, 1 [symbolic = %Self.2 (constants.%Self)]
+// CHECK:STDOUT:     %At.decl: @IndexWith.%At.type (%At.type.1) = fn_decl @At.1 [symbolic = @IndexWith.%At (constants.%At.1)] {
+// CHECK:STDOUT:       %self.patt: @At.1.%Self (%Self) = binding_pattern self
+// CHECK:STDOUT:       %self.param_patt: @At.1.%Self (%Self) = value_param_pattern %self.patt, runtime_param0
+// CHECK:STDOUT:       %subscript.patt: @At.1.%SubscriptType (%SubscriptType) = binding_pattern subscript
+// CHECK:STDOUT:       %subscript.param_patt: @At.1.%SubscriptType (%SubscriptType) = value_param_pattern %subscript.patt, runtime_param1
+// CHECK:STDOUT:       %return.patt: %.1 = return_slot_pattern
+// CHECK:STDOUT:       %return.param_patt: %.1 = out_param_pattern %return.patt, runtime_param2
+// CHECK:STDOUT:     } {
+// CHECK:STDOUT:       %.loc6_15.1: @At.1.%IndexWith.type (%IndexWith.type.2) = specific_constant @IndexWith.%Self.1, @IndexWith(constants.%SubscriptType) [symbolic = %Self (constants.%Self)]
+// CHECK:STDOUT:       %Self.ref: @At.1.%IndexWith.type (%IndexWith.type.2) = name_ref Self, %.loc6_15.1 [symbolic = %Self (constants.%Self)]
+// CHECK:STDOUT:       %.loc6_15.2: type = facet_type_access %Self.ref [symbolic = %Self (constants.%Self)]
+// CHECK:STDOUT:       %.loc6_15.3: type = converted %Self.ref, %.loc6_15.2 [symbolic = %Self (constants.%Self)]
+// CHECK:STDOUT:       %SubscriptType.ref: type = name_ref SubscriptType, @IndexWith.%SubscriptType.loc5_26.1 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:       %.loc6_51.1: %.1 = tuple_literal ()
+// CHECK:STDOUT:       %.loc6_51.2: type = converted %.loc6_51.1, constants.%.1 [template = constants.%.1]
+// CHECK:STDOUT:       %self.param: @At.1.%Self (%Self) = value_param runtime_param0
+// CHECK:STDOUT:       %self: @At.1.%Self (%Self) = bind_name self, %self.param
+// CHECK:STDOUT:       %subscript.param: @At.1.%SubscriptType (%SubscriptType) = value_param runtime_param1
+// CHECK:STDOUT:       %subscript: @At.1.%SubscriptType (%SubscriptType) = bind_name subscript, %subscript.param
+// CHECK:STDOUT:       %return.param: ref %.1 = out_param runtime_param2
+// CHECK:STDOUT:       %return: ref %.1 = return_slot %return.param
+// CHECK:STDOUT:     }
+// CHECK:STDOUT:     %.loc6_52.1: @IndexWith.%.loc6_52.2 (%.2) = assoc_entity element0, %At.decl [symbolic = %.loc6_52.3 (constants.%.3)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = %Self.1
+// CHECK:STDOUT:     .At = %.loc6_52.1
+// CHECK:STDOUT:     witness = (%At.decl)
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: impl @impl: %.loc9_7.2 as %IndexWith.type {
+// CHECK:STDOUT:   %At.decl: %At.type.2 = fn_decl @At.2 [template = constants.%At.2] {
+// CHECK:STDOUT:     %self.patt: %.1 = binding_pattern self
+// CHECK:STDOUT:     %self.param_patt: %.1 = value_param_pattern %self.patt, runtime_param0
+// CHECK:STDOUT:     %subscript.patt: %.1 = binding_pattern subscript
+// CHECK:STDOUT:     %subscript.param_patt: %.1 = value_param_pattern %subscript.patt, runtime_param1
+// CHECK:STDOUT:     %return.patt: %.1 = return_slot_pattern
+// CHECK:STDOUT:     %return.param_patt: %.1 = out_param_pattern %return.patt, runtime_param2
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %Self.ref: type = name_ref Self, @impl.%.loc9_7.2 [template = constants.%.1]
+// CHECK:STDOUT:     %.loc10_33.1: %.1 = tuple_literal ()
+// CHECK:STDOUT:     %.loc10_33.2: type = converted %.loc10_33.1, constants.%.1 [template = constants.%.1]
+// CHECK:STDOUT:     %.loc10_40.1: %.1 = tuple_literal ()
+// CHECK:STDOUT:     %.loc10_40.2: type = converted %.loc10_40.1, constants.%.1 [template = constants.%.1]
+// CHECK:STDOUT:     %self.param: %.1 = value_param runtime_param0
+// CHECK:STDOUT:     %self: %.1 = bind_name self, %self.param
+// CHECK:STDOUT:     %subscript.param: %.1 = value_param runtime_param1
+// CHECK:STDOUT:     %subscript: %.1 = bind_name subscript, %subscript.param
+// CHECK:STDOUT:     %return.param: ref %.1 = out_param runtime_param2
+// CHECK:STDOUT:     %return: ref %.1 = return_slot %return.param
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %.loc9_31: <witness> = interface_witness (%At.decl) [template = constants.%.6]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !members:
+// CHECK:STDOUT:   .At = %At.decl
+// CHECK:STDOUT:   witness = %.loc9_31
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @At.1(@IndexWith.%SubscriptType.loc5_26.1: type, @IndexWith.%Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2)) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 1 [symbolic = %Self (constants.%Self)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn[%self.param_patt: @At.1.%Self (%Self)](%subscript.param_patt: @At.1.%SubscriptType (%SubscriptType)) -> %.1;
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @At.2[%self.param_patt: %.1](%subscript.param_patt: %.1) -> %.1 {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc11_13: %.1 = tuple_literal ()
+// CHECK:STDOUT:   %tuple: %.1 = tuple_value () [template = constants.%tuple]
+// CHECK:STDOUT:   %.loc11_14: %.1 = converted %.loc11_13, %tuple [template = constants.%tuple]
+// CHECK:STDOUT:   return %.loc11_14
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %.loc15_11.1: %.1 = tuple_literal ()
+// CHECK:STDOUT:   %.loc15_14: %.1 = tuple_literal ()
+// CHECK:STDOUT:   %tuple.loc15_11: %.1 = tuple_value () [template = constants.%tuple]
+// CHECK:STDOUT:   %.loc15_11.2: %.1 = converted %.loc15_11.1, %tuple.loc15_11 [template = constants.%tuple]
+// CHECK:STDOUT:   %tuple.loc15_14: %.1 = tuple_value () [template = constants.%tuple]
+// CHECK:STDOUT:   %.loc15_15.1: %.1 = converted %.loc15_14, %tuple.loc15_14 [template = constants.%tuple]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(constants.%.1) [template = constants.%IndexWith.type.3]
+// CHECK:STDOUT:   %.loc15_15.2: %.4 = specific_constant @IndexWith.%.loc6_52.1, @IndexWith(constants.%.1) [template = constants.%.5]
+// CHECK:STDOUT:   %At.ref: %.4 = name_ref At, %.loc15_15.2 [template = constants.%.5]
+// CHECK:STDOUT:   %.loc15_15.3: %At.type.3 = interface_witness_access constants.%.6, element0 [template = constants.%At.2]
+// CHECK:STDOUT:   %.loc15_15.4: <bound method> = bound_method %.loc15_11.2, %.loc15_15.3 [template = constants.%.7]
+// CHECK:STDOUT:   %At.call: init %.1 = call %.loc15_15.4(%.loc15_11.2, %.loc15_15.1)
+// CHECK:STDOUT:   return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType) {
+// CHECK:STDOUT:   %SubscriptType.loc5_26.2 => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt.loc5_26.2 => constants.%SubscriptType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@At.1.%SubscriptType) {
+// CHECK:STDOUT:   %SubscriptType.loc5_26.2 => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt.loc5_26.2 => constants.%SubscriptType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At.1(constants.%SubscriptType, constants.%Self) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.2
+// CHECK:STDOUT:   %Self => constants.%Self
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@IndexWith.%SubscriptType.loc5_26.2) {
+// CHECK:STDOUT:   %SubscriptType.loc5_26.2 => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt.loc5_26.2 => constants.%SubscriptType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%.1) {
+// CHECK:STDOUT:   %SubscriptType.loc5_26.2 => constants.%.1
+// CHECK:STDOUT:   %SubscriptType.patt.loc5_26.2 => constants.%.1
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.3
+// CHECK:STDOUT:   %Self.2 => constants.%Self
+// CHECK:STDOUT:   %At.type => constants.%At.type.3
+// CHECK:STDOUT:   %At => constants.%At.3
+// CHECK:STDOUT:   %.loc6_52.2 => constants.%.4
+// CHECK:STDOUT:   %.loc6_52.3 => constants.%.5
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At.1(constants.%.1, constants.%.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%.1
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.3
+// CHECK:STDOUT:   %Self => constants.%.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
diff --git a/toolchain/check/testdata/operators/overloaded/ordered.carbon b/toolchain/check/testdata/operators/overloaded/ordered.carbon
index a156472f6447..d400f6b9812a 100644
--- a/toolchain/check/testdata/operators/overloaded/ordered.carbon
+++ b/toolchain/check/testdata/operators/overloaded/ordered.carbon
@@ -130,6 +130,7 @@ fn TestGreaterEqual(a: D, b: D) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -522,6 +523,7 @@ fn TestGreaterEqual(a: D, b: D) -> bool {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/right_shift.carbon b/toolchain/check/testdata/operators/overloaded/right_shift.carbon
index 55f4882ca614..29a67015ec64 100644
--- a/toolchain/check/testdata/operators/overloaded/right_shift.carbon
+++ b/toolchain/check/testdata/operators/overloaded/right_shift.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/operators/overloaded/sub.carbon b/toolchain/check/testdata/operators/overloaded/sub.carbon
index faca34551d74..1e854ec8d889 100644
--- a/toolchain/check/testdata/operators/overloaded/sub.carbon
+++ b/toolchain/check/testdata/operators/overloaded/sub.carbon
@@ -75,6 +75,7 @@ fn TestAssign(a: C*, b: C) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/package_expr/fail_not_found.carbon b/toolchain/check/testdata/package_expr/fail_not_found.carbon
index 86dac2afe296..628f67cf114a 100644
--- a/toolchain/check/testdata/package_expr/fail_not_found.carbon
+++ b/toolchain/check/testdata/package_expr/fail_not_found.carbon
@@ -33,6 +33,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/package_expr/syntax.carbon b/toolchain/check/testdata/package_expr/syntax.carbon
index 2c1b9908dddc..1d7d34312a2e 100644
--- a/toolchain/check/testdata/package_expr/syntax.carbon
+++ b/toolchain/check/testdata/package_expr/syntax.carbon
@@ -58,6 +58,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -117,6 +118,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -190,6 +192,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/explicit_imports.carbon b/toolchain/check/testdata/packages/explicit_imports.carbon
index f40df9067239..27cc24e15752 100644
--- a/toolchain/check/testdata/packages/explicit_imports.carbon
+++ b/toolchain/check/testdata/packages/explicit_imports.carbon
@@ -47,6 +47,7 @@ import library "main_lib_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -69,6 +70,7 @@ import library "main_lib_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -91,6 +93,7 @@ import library "main_lib_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -114,6 +117,7 @@ import library "main_lib_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -142,6 +146,7 @@ import library "main_lib_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -164,6 +169,7 @@ import library "main_lib_api";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_api_not_found.carbon b/toolchain/check/testdata/packages/fail_api_not_found.carbon
index d604aeae39cc..4ae77761a0f8 100644
--- a/toolchain/check/testdata/packages/fail_api_not_found.carbon
+++ b/toolchain/check/testdata/packages/fail_api_not_found.carbon
@@ -40,6 +40,7 @@ impl library "[[@TEST_NAME]]";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -64,6 +65,7 @@ impl library "[[@TEST_NAME]]";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -88,6 +90,7 @@ impl library "[[@TEST_NAME]]";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_conflict_no_namespaces.carbon b/toolchain/check/testdata/packages/fail_conflict_no_namespaces.carbon
index a6c9b28c988f..21878fa59164 100644
--- a/toolchain/check/testdata/packages/fail_conflict_no_namespaces.carbon
+++ b/toolchain/check/testdata/packages/fail_conflict_no_namespaces.carbon
@@ -50,6 +50,7 @@ import library "var";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -83,6 +84,7 @@ import library "var";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -116,6 +118,7 @@ import library "var";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_cycle.carbon b/toolchain/check/testdata/packages/fail_cycle.carbon
index 8b890ce387f3..3baf97fa43cc 100644
--- a/toolchain/check/testdata/packages/fail_cycle.carbon
+++ b/toolchain/check/testdata/packages/fail_cycle.carbon
@@ -64,6 +64,7 @@ import B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -91,6 +92,7 @@ import B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -118,6 +120,7 @@ import B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -145,6 +148,7 @@ import B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -169,6 +173,7 @@ import B;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_duplicate_api.carbon b/toolchain/check/testdata/packages/fail_duplicate_api.carbon
index fb5623bacff2..d874cdce8904 100644
--- a/toolchain/check/testdata/packages/fail_duplicate_api.carbon
+++ b/toolchain/check/testdata/packages/fail_duplicate_api.carbon
@@ -58,6 +58,7 @@ package Package library "lib";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -80,6 +81,7 @@ package Package library "lib";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -102,6 +104,7 @@ package Package library "lib";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -124,6 +127,7 @@ package Package library "lib";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -146,6 +150,7 @@ package Package library "lib";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -168,6 +173,7 @@ package Package library "lib";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -190,6 +196,7 @@ package Package library "lib";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -212,6 +219,7 @@ package Package library "lib";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_extension.carbon b/toolchain/check/testdata/packages/fail_extension.carbon
index d3e2b8ad43c3..97092740332c 100644
--- a/toolchain/check/testdata/packages/fail_extension.carbon
+++ b/toolchain/check/testdata/packages/fail_extension.carbon
@@ -93,6 +93,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -115,6 +116,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -137,6 +139,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -159,6 +162,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -183,6 +187,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -205,6 +210,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -229,6 +235,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -251,6 +258,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -275,6 +283,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -297,6 +306,7 @@ impl package SwappedExt;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_import_default.carbon b/toolchain/check/testdata/packages/fail_import_default.carbon
index 2d76ba3132e5..df53ddcdf1c3 100644
--- a/toolchain/check/testdata/packages/fail_import_default.carbon
+++ b/toolchain/check/testdata/packages/fail_import_default.carbon
@@ -54,6 +54,7 @@ import library default;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -76,6 +77,7 @@ import library default;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -100,6 +102,7 @@ import library default;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -122,6 +125,7 @@ import library default;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_import_invalid.carbon b/toolchain/check/testdata/packages/fail_import_invalid.carbon
index 4de0fa10f500..c5d412aea34f 100644
--- a/toolchain/check/testdata/packages/fail_import_invalid.carbon
+++ b/toolchain/check/testdata/packages/fail_import_invalid.carbon
@@ -103,6 +103,7 @@ import ImportNotFound;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -125,6 +126,7 @@ import ImportNotFound;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -147,6 +149,7 @@ import ImportNotFound;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -169,6 +172,7 @@ import ImportNotFound;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -191,6 +195,7 @@ import ImportNotFound;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -213,6 +218,7 @@ import ImportNotFound;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -237,6 +243,7 @@ import ImportNotFound;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -259,6 +266,7 @@ import ImportNotFound;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -283,6 +291,7 @@ import ImportNotFound;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_import_repeat.carbon b/toolchain/check/testdata/packages/fail_import_repeat.carbon
index ef1dd72dceb5..647776aa0f43 100644
--- a/toolchain/check/testdata/packages/fail_import_repeat.carbon
+++ b/toolchain/check/testdata/packages/fail_import_repeat.carbon
@@ -74,6 +74,7 @@ import library default;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -96,6 +97,7 @@ import library default;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -118,6 +120,7 @@ import library default;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -140,6 +143,7 @@ import library default;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -169,6 +173,7 @@ import library default;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_import_type_error.carbon b/toolchain/check/testdata/packages/fail_import_type_error.carbon
index d066ab75778e..f74355006258 100644
--- a/toolchain/check/testdata/packages/fail_import_type_error.carbon
+++ b/toolchain/check/testdata/packages/fail_import_type_error.carbon
@@ -52,6 +52,7 @@ var d: i32 = d_ref;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -104,6 +105,7 @@ var d: i32 = d_ref;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_name_with_import_failure.carbon b/toolchain/check/testdata/packages/fail_name_with_import_failure.carbon
index faf91ab44053..5b9e9fccc879 100644
--- a/toolchain/check/testdata/packages/fail_name_with_import_failure.carbon
+++ b/toolchain/check/testdata/packages/fail_name_with_import_failure.carbon
@@ -30,6 +30,7 @@ var a: () = A();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/fail_package_main.carbon b/toolchain/check/testdata/packages/fail_package_main.carbon
index b1da8dbc95b2..de79e6d05330 100644
--- a/toolchain/check/testdata/packages/fail_package_main.carbon
+++ b/toolchain/check/testdata/packages/fail_package_main.carbon
@@ -49,6 +49,7 @@ package Main library "[[@TEST_NAME]]";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -71,6 +72,7 @@ package Main library "[[@TEST_NAME]]";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -93,6 +95,7 @@ package Main library "[[@TEST_NAME]]";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -115,6 +118,7 @@ package Main library "[[@TEST_NAME]]";
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/implicit_imports_prelude.carbon b/toolchain/check/testdata/packages/implicit_imports_prelude.carbon
index f0c64338ae7a..de806bbdb591 100644
--- a/toolchain/check/testdata/packages/implicit_imports_prelude.carbon
+++ b/toolchain/check/testdata/packages/implicit_imports_prelude.carbon
@@ -39,6 +39,7 @@ var b: i32 = a;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -85,6 +86,7 @@ var b: i32 = a;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/loaded_global.carbon b/toolchain/check/testdata/packages/loaded_global.carbon
index 3b5bcb2a0a18..d7810e72a3b4 100644
--- a/toolchain/check/testdata/packages/loaded_global.carbon
+++ b/toolchain/check/testdata/packages/loaded_global.carbon
@@ -53,6 +53,7 @@ var package_b: () = package.B();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -86,6 +87,7 @@ var package_b: () = package.B();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -141,6 +143,7 @@ var package_b: () = package.B();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -174,6 +177,7 @@ var package_b: () = package.B();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/packages/unused_lazy_import.carbon b/toolchain/check/testdata/packages/unused_lazy_import.carbon
index 2c32f64e3f7c..e88fcca20154 100644
--- a/toolchain/check/testdata/packages/unused_lazy_import.carbon
+++ b/toolchain/check/testdata/packages/unused_lazy_import.carbon
@@ -33,6 +33,7 @@ impl package Implicit;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -60,6 +61,7 @@ impl package Implicit;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/address_of_deref.carbon b/toolchain/check/testdata/pointer/address_of_deref.carbon
index 0049c4d8e3bf..76c53e714753 100644
--- a/toolchain/check/testdata/pointer/address_of_deref.carbon
+++ b/toolchain/check/testdata/pointer/address_of_deref.carbon
@@ -33,6 +33,7 @@ fn F() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/address_of_lvalue.carbon b/toolchain/check/testdata/pointer/address_of_lvalue.carbon
index 1e7aaeb0b4d0..df012033c73a 100644
--- a/toolchain/check/testdata/pointer/address_of_lvalue.carbon
+++ b/toolchain/check/testdata/pointer/address_of_lvalue.carbon
@@ -49,6 +49,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/arrow.carbon b/toolchain/check/testdata/pointer/arrow.carbon
index 3777122311ed..06a3f81f5db1 100644
--- a/toolchain/check/testdata/pointer/arrow.carbon
+++ b/toolchain/check/testdata/pointer/arrow.carbon
@@ -46,6 +46,7 @@ fn Foo(ptr: C*) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/basic.carbon b/toolchain/check/testdata/pointer/basic.carbon
index fa9e7896a6f4..f505a87b523d 100644
--- a/toolchain/check/testdata/pointer/basic.carbon
+++ b/toolchain/check/testdata/pointer/basic.carbon
@@ -35,6 +35,7 @@ fn F() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/fail_address_of_error.carbon b/toolchain/check/testdata/pointer/fail_address_of_error.carbon
index 349c70a86e42..d46defd2a0f1 100644
--- a/toolchain/check/testdata/pointer/fail_address_of_error.carbon
+++ b/toolchain/check/testdata/pointer/fail_address_of_error.carbon
@@ -39,6 +39,7 @@ fn Test() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/fail_address_of_value.carbon b/toolchain/check/testdata/pointer/fail_address_of_value.carbon
index b2a3eb21d173..9a262e65286c 100644
--- a/toolchain/check/testdata/pointer/fail_address_of_value.carbon
+++ b/toolchain/check/testdata/pointer/fail_address_of_value.carbon
@@ -151,6 +151,7 @@ fn AddressOfParam(param: i32) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/fail_deref_error.carbon b/toolchain/check/testdata/pointer/fail_deref_error.carbon
index 8bcefd8fb5a0..bf52476e77ee 100644
--- a/toolchain/check/testdata/pointer/fail_deref_error.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_error.carbon
@@ -34,6 +34,7 @@ let n2: i32 = undeclared->foo;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/fail_deref_function.carbon b/toolchain/check/testdata/pointer/fail_deref_function.carbon
index 1196a7669a87..def0b04704c4 100644
--- a/toolchain/check/testdata/pointer/fail_deref_function.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_function.carbon
@@ -35,6 +35,7 @@ fn A() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/fail_deref_namespace.carbon b/toolchain/check/testdata/pointer/fail_deref_namespace.carbon
index 5015002daa06..4c88727d0f71 100644
--- a/toolchain/check/testdata/pointer/fail_deref_namespace.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_namespace.carbon
@@ -37,6 +37,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/fail_deref_not_pointer.carbon b/toolchain/check/testdata/pointer/fail_deref_not_pointer.carbon
index 0f02e7ee599c..633537165fd7 100644
--- a/toolchain/check/testdata/pointer/fail_deref_not_pointer.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_not_pointer.carbon
@@ -61,6 +61,7 @@ fn Deref(n: i32) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/fail_deref_type.carbon b/toolchain/check/testdata/pointer/fail_deref_type.carbon
index c0e248d5607a..8f0007229c0b 100644
--- a/toolchain/check/testdata/pointer/fail_deref_type.carbon
+++ b/toolchain/check/testdata/pointer/fail_deref_type.carbon
@@ -37,6 +37,7 @@ var p2: i32->foo;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/fail_type_mismatch.carbon b/toolchain/check/testdata/pointer/fail_type_mismatch.carbon
index c80118e91cb7..3f49544f8308 100644
--- a/toolchain/check/testdata/pointer/fail_type_mismatch.carbon
+++ b/toolchain/check/testdata/pointer/fail_type_mismatch.carbon
@@ -56,6 +56,7 @@ fn ConstMismatch(p: const {}*) -> const ({}*) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/import.carbon b/toolchain/check/testdata/pointer/import.carbon
index 36d53180be6d..4dba088e232c 100644
--- a/toolchain/check/testdata/pointer/import.carbon
+++ b/toolchain/check/testdata/pointer/import.carbon
@@ -39,6 +39,7 @@ var a: i32* = a_ref;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -97,6 +98,7 @@ var a: i32* = a_ref;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/nested_const.carbon b/toolchain/check/testdata/pointer/nested_const.carbon
index 023c3267a4d5..bf36526d9b74 100644
--- a/toolchain/check/testdata/pointer/nested_const.carbon
+++ b/toolchain/check/testdata/pointer/nested_const.carbon
@@ -36,6 +36,7 @@ fn F(p: const (const (const i32*)*)) -> const i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/pointer/types.carbon b/toolchain/check/testdata/pointer/types.carbon
index 6856828f52f8..7c455c88a026 100644
--- a/toolchain/check/testdata/pointer/types.carbon
+++ b/toolchain/check/testdata/pointer/types.carbon
@@ -39,6 +39,7 @@ fn ConstPtr(p: const i32*) -> (const i32)* {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/code_after_return.carbon b/toolchain/check/testdata/return/code_after_return.carbon
index 21bcb30960e3..c7d463a1e22d 100644
--- a/toolchain/check/testdata/return/code_after_return.carbon
+++ b/toolchain/check/testdata/return/code_after_return.carbon
@@ -32,6 +32,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/code_after_return_value.carbon b/toolchain/check/testdata/return/code_after_return_value.carbon
index 1ed8c1f7959b..565f308ba611 100644
--- a/toolchain/check/testdata/return/code_after_return_value.carbon
+++ b/toolchain/check/testdata/return/code_after_return_value.carbon
@@ -46,6 +46,7 @@ fn F(b: bool) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_call_in_type.carbon b/toolchain/check/testdata/return/fail_call_in_type.carbon
index 0c63f5f00bce..309f4f0c3657 100644
--- a/toolchain/check/testdata/return/fail_call_in_type.carbon
+++ b/toolchain/check/testdata/return/fail_call_in_type.carbon
@@ -37,6 +37,7 @@ fn Six() -> ReturnType() { return 6; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_error_in_type.carbon b/toolchain/check/testdata/return/fail_error_in_type.carbon
index f50987dab4ce..2f4010a27a83 100644
--- a/toolchain/check/testdata/return/fail_error_in_type.carbon
+++ b/toolchain/check/testdata/return/fail_error_in_type.carbon
@@ -28,6 +28,7 @@ fn Six() -> x;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_missing_return.carbon b/toolchain/check/testdata/return/fail_missing_return.carbon
index 7faab33dc1e3..0992333624a2 100644
--- a/toolchain/check/testdata/return/fail_missing_return.carbon
+++ b/toolchain/check/testdata/return/fail_missing_return.carbon
@@ -32,6 +32,7 @@ fn Main() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_missing_return_empty_tuple.carbon b/toolchain/check/testdata/return/fail_missing_return_empty_tuple.carbon
index d24ac84a3c37..0b9382374c11 100644
--- a/toolchain/check/testdata/return/fail_missing_return_empty_tuple.carbon
+++ b/toolchain/check/testdata/return/fail_missing_return_empty_tuple.carbon
@@ -29,6 +29,7 @@ fn F() -> () {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_return_var_no_returned_var.carbon b/toolchain/check/testdata/return/fail_return_var_no_returned_var.carbon
index ad1df16ed419..353497d8511e 100644
--- a/toolchain/check/testdata/return/fail_return_var_no_returned_var.carbon
+++ b/toolchain/check/testdata/return/fail_return_var_no_returned_var.carbon
@@ -33,6 +33,7 @@ fn Procedure() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_return_with_returned_var.carbon b/toolchain/check/testdata/return/fail_return_with_returned_var.carbon
index 4eeb70bef27c..4e8a3cd0b90d 100644
--- a/toolchain/check/testdata/return/fail_return_with_returned_var.carbon
+++ b/toolchain/check/testdata/return/fail_return_with_returned_var.carbon
@@ -61,6 +61,7 @@ fn G() -> C {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_returned_var_no_return_type.carbon b/toolchain/check/testdata/return/fail_returned_var_no_return_type.carbon
index 1f529bd3dd18..ecfc8b5bdc9a 100644
--- a/toolchain/check/testdata/return/fail_returned_var_no_return_type.carbon
+++ b/toolchain/check/testdata/return/fail_returned_var_no_return_type.carbon
@@ -34,6 +34,7 @@ fn Procedure() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_returned_var_shadow.carbon b/toolchain/check/testdata/return/fail_returned_var_shadow.carbon
index 500f7572ee7f..6255b516338e 100644
--- a/toolchain/check/testdata/return/fail_returned_var_shadow.carbon
+++ b/toolchain/check/testdata/return/fail_returned_var_shadow.carbon
@@ -62,6 +62,7 @@ fn DifferentScopes() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_returned_var_type.carbon b/toolchain/check/testdata/return/fail_returned_var_type.carbon
index a0e933d50073..3ba01f92db30 100644
--- a/toolchain/check/testdata/return/fail_returned_var_type.carbon
+++ b/toolchain/check/testdata/return/fail_returned_var_type.carbon
@@ -42,6 +42,7 @@ fn Mismatch() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_type_mismatch.carbon b/toolchain/check/testdata/return/fail_type_mismatch.carbon
index f454662c0542..5297d9187be4 100644
--- a/toolchain/check/testdata/return/fail_type_mismatch.carbon
+++ b/toolchain/check/testdata/return/fail_type_mismatch.carbon
@@ -55,6 +55,7 @@ fn Main() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_value_disallowed.carbon b/toolchain/check/testdata/return/fail_value_disallowed.carbon
index 3a486949caea..d82a5bd6d794 100644
--- a/toolchain/check/testdata/return/fail_value_disallowed.carbon
+++ b/toolchain/check/testdata/return/fail_value_disallowed.carbon
@@ -34,6 +34,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_value_missing.carbon b/toolchain/check/testdata/return/fail_value_missing.carbon
index 31b9f7ffaeff..7cbcc16de2c3 100644
--- a/toolchain/check/testdata/return/fail_value_missing.carbon
+++ b/toolchain/check/testdata/return/fail_value_missing.carbon
@@ -36,6 +36,7 @@ fn Main() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/fail_var_in_type.carbon b/toolchain/check/testdata/return/fail_var_in_type.carbon
index 2e181b931d90..30501660c863 100644
--- a/toolchain/check/testdata/return/fail_var_in_type.carbon
+++ b/toolchain/check/testdata/return/fail_var_in_type.carbon
@@ -33,6 +33,7 @@ fn Six() -> x { return 6; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/missing_return_no_return_type.carbon b/toolchain/check/testdata/return/missing_return_no_return_type.carbon
index 08b4a8441ab6..cb2ac0d60dc8 100644
--- a/toolchain/check/testdata/return/missing_return_no_return_type.carbon
+++ b/toolchain/check/testdata/return/missing_return_no_return_type.carbon
@@ -26,6 +26,7 @@ fn F() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/no_value.carbon b/toolchain/check/testdata/return/no_value.carbon
index 70d4292bd08c..9c21fa0fd203 100644
--- a/toolchain/check/testdata/return/no_value.carbon
+++ b/toolchain/check/testdata/return/no_value.carbon
@@ -27,6 +27,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/returned_var.carbon b/toolchain/check/testdata/return/returned_var.carbon
index 73ba04ce10a2..ddef9f7cb3f0 100644
--- a/toolchain/check/testdata/return/returned_var.carbon
+++ b/toolchain/check/testdata/return/returned_var.carbon
@@ -52,6 +52,7 @@ fn G() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/returned_var_scope.carbon b/toolchain/check/testdata/return/returned_var_scope.carbon
index ee2b4bd731bf..961edb1fe702 100644
--- a/toolchain/check/testdata/return/returned_var_scope.carbon
+++ b/toolchain/check/testdata/return/returned_var_scope.carbon
@@ -53,6 +53,7 @@ fn EnclosingButAfter(b: bool) -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/struct.carbon b/toolchain/check/testdata/return/struct.carbon
index bfa89002a67d..e2cac278caef 100644
--- a/toolchain/check/testdata/return/struct.carbon
+++ b/toolchain/check/testdata/return/struct.carbon
@@ -33,6 +33,7 @@ fn Main() -> {.a: i32} {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/tuple.carbon b/toolchain/check/testdata/return/tuple.carbon
index 26b91f10cfdd..850cb55d4729 100644
--- a/toolchain/check/testdata/return/tuple.carbon
+++ b/toolchain/check/testdata/return/tuple.carbon
@@ -37,6 +37,7 @@ fn Main() -> (i32, i32) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/return/value.carbon b/toolchain/check/testdata/return/value.carbon
index 42dada9f959c..4325bfb2bd0b 100644
--- a/toolchain/check/testdata/return/value.carbon
+++ b/toolchain/check/testdata/return/value.carbon
@@ -31,6 +31,7 @@ fn Main() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_access_into_invalid.carbon b/toolchain/check/testdata/struct/fail_access_into_invalid.carbon
index dbb345176a61..9184c930b24b 100644
--- a/toolchain/check/testdata/struct/fail_access_into_invalid.carbon
+++ b/toolchain/check/testdata/struct/fail_access_into_invalid.carbon
@@ -29,6 +29,7 @@ fn F() { a.b; }
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_assign_empty.carbon b/toolchain/check/testdata/struct/fail_assign_empty.carbon
index 16c948904e6b..a8790f418998 100644
--- a/toolchain/check/testdata/struct/fail_assign_empty.carbon
+++ b/toolchain/check/testdata/struct/fail_assign_empty.carbon
@@ -31,6 +31,7 @@ var x: {.a: i32} = {};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_assign_to_empty.carbon b/toolchain/check/testdata/struct/fail_assign_to_empty.carbon
index 521bcc844bca..42394041e5ac 100644
--- a/toolchain/check/testdata/struct/fail_assign_to_empty.carbon
+++ b/toolchain/check/testdata/struct/fail_assign_to_empty.carbon
@@ -29,6 +29,7 @@ var x: {} = {.a = 1};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_duplicate_name.carbon b/toolchain/check/testdata/struct/fail_duplicate_name.carbon
index fcfcef9afdbd..0f7b3126b0cb 100644
--- a/toolchain/check/testdata/struct/fail_duplicate_name.carbon
+++ b/toolchain/check/testdata/struct/fail_duplicate_name.carbon
@@ -77,6 +77,7 @@ var y: {.b: i32, .c: i32} = {.b = 3, .b = 4};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_field_name_mismatch.carbon b/toolchain/check/testdata/struct/fail_field_name_mismatch.carbon
index 735c41bc940c..4b59f9604f78 100644
--- a/toolchain/check/testdata/struct/fail_field_name_mismatch.carbon
+++ b/toolchain/check/testdata/struct/fail_field_name_mismatch.carbon
@@ -38,6 +38,7 @@ var y: {.b: i32} = x;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_field_type_mismatch.carbon b/toolchain/check/testdata/struct/fail_field_type_mismatch.carbon
index 5701ad37e917..665995ff524b 100644
--- a/toolchain/check/testdata/struct/fail_field_type_mismatch.carbon
+++ b/toolchain/check/testdata/struct/fail_field_type_mismatch.carbon
@@ -32,6 +32,7 @@ var x: {.a: i32} = {.b = 1.0};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_member_access_type.carbon b/toolchain/check/testdata/struct/fail_member_access_type.carbon
index d284dd777b0f..0e6703ce0af9 100644
--- a/toolchain/check/testdata/struct/fail_member_access_type.carbon
+++ b/toolchain/check/testdata/struct/fail_member_access_type.carbon
@@ -37,6 +37,7 @@ var y: i32 = x.b;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_member_of_function.carbon b/toolchain/check/testdata/struct/fail_member_of_function.carbon
index 5283124e6098..cf5132401e1f 100644
--- a/toolchain/check/testdata/struct/fail_member_of_function.carbon
+++ b/toolchain/check/testdata/struct/fail_member_of_function.carbon
@@ -30,6 +30,7 @@ fn A() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_non_member_access.carbon b/toolchain/check/testdata/struct/fail_non_member_access.carbon
index 4ab2f8c96412..e3710b06f894 100644
--- a/toolchain/check/testdata/struct/fail_non_member_access.carbon
+++ b/toolchain/check/testdata/struct/fail_non_member_access.carbon
@@ -33,6 +33,7 @@ var y: i32 = x.b;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_too_few_values.carbon b/toolchain/check/testdata/struct/fail_too_few_values.carbon
index 368cf4ec1bad..1d1ab50e3514 100644
--- a/toolchain/check/testdata/struct/fail_too_few_values.carbon
+++ b/toolchain/check/testdata/struct/fail_too_few_values.carbon
@@ -33,6 +33,7 @@ var x: {.a: i32, .b: i32} = {.a = 1};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_type_assign.carbon b/toolchain/check/testdata/struct/fail_type_assign.carbon
index 8494a399d6ba..6b7cd2e58144 100644
--- a/toolchain/check/testdata/struct/fail_type_assign.carbon
+++ b/toolchain/check/testdata/struct/fail_type_assign.carbon
@@ -51,6 +51,7 @@ var x: {.a: i32} = {.a: i32};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/fail_value_as_type.carbon b/toolchain/check/testdata/struct/fail_value_as_type.carbon
index 069ee282fb8c..66566d722362 100644
--- a/toolchain/check/testdata/struct/fail_value_as_type.carbon
+++ b/toolchain/check/testdata/struct/fail_value_as_type.carbon
@@ -50,6 +50,7 @@ var x: {.a = 1};
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/import.carbon b/toolchain/check/testdata/struct/import.carbon
index 3fab69c9a678..4a879ea6d69a 100644
--- a/toolchain/check/testdata/struct/import.carbon
+++ b/toolchain/check/testdata/struct/import.carbon
@@ -95,6 +95,7 @@ var c_bad: C({.a = 3, .b = 4}) = F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -264,6 +265,7 @@ var c_bad: C({.a = 3, .b = 4}) = F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -418,6 +420,7 @@ var c_bad: C({.a = 3, .b = 4}) = F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -535,6 +538,7 @@ var c_bad: C({.a = 3, .b = 4}) = F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/literal_member_access.carbon b/toolchain/check/testdata/struct/literal_member_access.carbon
index 3c9e3cb4420e..179e70616224 100644
--- a/toolchain/check/testdata/struct/literal_member_access.carbon
+++ b/toolchain/check/testdata/struct/literal_member_access.carbon
@@ -41,6 +41,7 @@ fn F() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/member_access.carbon b/toolchain/check/testdata/struct/member_access.carbon
index c864f65d19d5..21accb6263c4 100644
--- a/toolchain/check/testdata/struct/member_access.carbon
+++ b/toolchain/check/testdata/struct/member_access.carbon
@@ -37,6 +37,7 @@ var z: i32 = y;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/nested_struct_in_place.carbon b/toolchain/check/testdata/struct/nested_struct_in_place.carbon
index 7fee4f529c0e..8579ef9b032d 100644
--- a/toolchain/check/testdata/struct/nested_struct_in_place.carbon
+++ b/toolchain/check/testdata/struct/nested_struct_in_place.carbon
@@ -40,6 +40,7 @@ fn G() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/one_entry.carbon b/toolchain/check/testdata/struct/one_entry.carbon
index a5e23c303c39..e1d282d62c49 100644
--- a/toolchain/check/testdata/struct/one_entry.carbon
+++ b/toolchain/check/testdata/struct/one_entry.carbon
@@ -30,6 +30,7 @@ var y: {.a: i32} = x;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/reorder_fields.carbon b/toolchain/check/testdata/struct/reorder_fields.carbon
index e8f09dc315d2..28c303ae97f0 100644
--- a/toolchain/check/testdata/struct/reorder_fields.carbon
+++ b/toolchain/check/testdata/struct/reorder_fields.carbon
@@ -47,6 +47,7 @@ fn F() -> {.a: i32, .b: f64} {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/tuple_as_element.carbon b/toolchain/check/testdata/struct/tuple_as_element.carbon
index ac1564a214aa..9efeaae31f17 100644
--- a/toolchain/check/testdata/struct/tuple_as_element.carbon
+++ b/toolchain/check/testdata/struct/tuple_as_element.carbon
@@ -35,6 +35,7 @@ var y: {.a: i32, .b: (i32,)} = x;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/struct/two_entries.carbon b/toolchain/check/testdata/struct/two_entries.carbon
index 9911606b9213..04148a028167 100644
--- a/toolchain/check/testdata/struct/two_entries.carbon
+++ b/toolchain/check/testdata/struct/two_entries.carbon
@@ -35,6 +35,7 @@ var y: {.a: i32, .b: i32} = x;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/element_access.carbon b/toolchain/check/testdata/tuple/access/element_access.carbon
index ba72b3ecf721..de2be4a60a9c 100644
--- a/toolchain/check/testdata/tuple/access/element_access.carbon
+++ b/toolchain/check/testdata/tuple/access/element_access.carbon
@@ -33,6 +33,7 @@ var c: i32 = b.0;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/fail_access_error.carbon b/toolchain/check/testdata/tuple/access/fail_access_error.carbon
index b27f9ddf38dd..f033f77bf851 100644
--- a/toolchain/check/testdata/tuple/access/fail_access_error.carbon
+++ b/toolchain/check/testdata/tuple/access/fail_access_error.carbon
@@ -36,6 +36,7 @@ var b: i32 = a.(oops);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/fail_empty_access.carbon b/toolchain/check/testdata/tuple/access/fail_empty_access.carbon
index 448b666eab98..db6802fca9bc 100644
--- a/toolchain/check/testdata/tuple/access/fail_empty_access.carbon
+++ b/toolchain/check/testdata/tuple/access/fail_empty_access.carbon
@@ -35,6 +35,7 @@ fn Run() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/fail_large_index.carbon b/toolchain/check/testdata/tuple/access/fail_large_index.carbon
index d03ae27b2c65..f2f066e308a4 100644
--- a/toolchain/check/testdata/tuple/access/fail_large_index.carbon
+++ b/toolchain/check/testdata/tuple/access/fail_large_index.carbon
@@ -42,6 +42,7 @@ var d: i32 = b.(0x7FFF_FFFF);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/fail_negative_indexing.carbon b/toolchain/check/testdata/tuple/access/fail_negative_indexing.carbon
index d7cba1ce3a18..8d3f86b9fbe0 100644
--- a/toolchain/check/testdata/tuple/access/fail_negative_indexing.carbon
+++ b/toolchain/check/testdata/tuple/access/fail_negative_indexing.carbon
@@ -44,6 +44,7 @@ var b: i32 = a.(-10);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/fail_non_deterministic_type.carbon b/toolchain/check/testdata/tuple/access/fail_non_deterministic_type.carbon
index 6001d23b9579..bc419b24b85d 100644
--- a/toolchain/check/testdata/tuple/access/fail_non_deterministic_type.carbon
+++ b/toolchain/check/testdata/tuple/access/fail_non_deterministic_type.carbon
@@ -38,6 +38,7 @@ var c: i32 = a.(b);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/fail_non_int_indexing.carbon b/toolchain/check/testdata/tuple/access/fail_non_int_indexing.carbon
index 039741959e55..5f85c91df10f 100644
--- a/toolchain/check/testdata/tuple/access/fail_non_int_indexing.carbon
+++ b/toolchain/check/testdata/tuple/access/fail_non_int_indexing.carbon
@@ -58,6 +58,7 @@ var b: i32 = a.(2.6);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/fail_non_tuple_access.carbon b/toolchain/check/testdata/tuple/access/fail_non_tuple_access.carbon
index 8d2f790404b5..7a82e9d2c456 100644
--- a/toolchain/check/testdata/tuple/access/fail_non_tuple_access.carbon
+++ b/toolchain/check/testdata/tuple/access/fail_non_tuple_access.carbon
@@ -30,29 +30,49 @@ fn Main() {
 // CHECK:STDOUT:   %Main: %Main.type = struct_value () [template]
 // CHECK:STDOUT:   %.2: i32 = int_literal 0 [template]
 // CHECK:STDOUT:   %.3: i32 = int_literal 1 [template]
+// CHECK:STDOUT:   %IndexWith.type.1: type = generic_interface_type @IndexWith [template]
+// CHECK:STDOUT:   %IndexWith: %IndexWith.type.1 = struct_value () [template]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %IndexWith.type.2: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2) = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic]
+// CHECK:STDOUT:   %Self.2: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic]
+// CHECK:STDOUT:   %At.type: type = fn_type @At, @IndexWith(%SubscriptType, %ElementType) [symbolic]
+// CHECK:STDOUT:   %At: %At.type = struct_value () [symbolic]
+// CHECK:STDOUT:   %.4: type = assoc_entity_type %IndexWith.type.2, %At.type [symbolic]
+// CHECK:STDOUT:   %.5: %.4 = assoc_entity element0, imports.%import_ref.5 [symbolic]
 // CHECK:STDOUT:   %Int32.type: type = fn_type @Int32 [template]
 // CHECK:STDOUT:   %Int32: %Int32.type = struct_value () [template]
-// CHECK:STDOUT:   %.4: i32 = int_literal 2 [template]
-// CHECK:STDOUT:   %.5: type = array_type %.4, i32 [template]
-// CHECK:STDOUT:   %.6: type = ptr_type %.5 [template]
-// CHECK:STDOUT:   %.7: i32 = int_literal 5 [template]
-// CHECK:STDOUT:   %.8: type = tuple_type (i32, i32) [template]
-// CHECK:STDOUT:   %array: %.5 = tuple_value (%.7, %.7) [template]
+// CHECK:STDOUT:   %.6: i32 = int_literal 2 [template]
+// CHECK:STDOUT:   %.7: type = array_type %.6, i32 [template]
+// CHECK:STDOUT:   %.8: type = ptr_type %.7 [template]
+// CHECK:STDOUT:   %.9: i32 = int_literal 5 [template]
+// CHECK:STDOUT:   %.10: type = tuple_type (i32, i32) [template]
+// CHECK:STDOUT:   %array: %.7 = tuple_value (%.9, %.9) [template]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [template] {
-// CHECK:STDOUT:     .Int32 = %import_ref
+// CHECK:STDOUT:     .IndexWith = %import_ref.1
+// CHECK:STDOUT:     .Int32 = %import_ref.6
 // CHECK:STDOUT:     import Core//prelude
 // CHECK:STDOUT:     import Core//prelude/operators
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %import_ref: %Int32.type = import_ref Core//prelude/types, inst+15, loaded [template = constants.%Int32]
+// CHECK:STDOUT:   %import_ref.1: %IndexWith.type.1 = import_ref Core//prelude/operators/index, inst+13, loaded [template = constants.%IndexWith]
+// CHECK:STDOUT:   %import_ref.2 = import_ref Core//prelude/operators/index, inst+22, unloaded
+// CHECK:STDOUT:   %import_ref.3 = import_ref Core//prelude/operators/index, inst+50, unloaded
+// CHECK:STDOUT:   %import_ref.4 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT:   %import_ref.5 = import_ref Core//prelude/operators/index, inst+42, unloaded
+// CHECK:STDOUT:   %import_ref.6: %Int32.type = import_ref Core//prelude/types, inst+15, loaded [template = constants.%Int32]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
@@ -64,39 +84,98 @@ fn Main() {
 // CHECK:STDOUT:   %Main.decl: %Main.type = fn_decl @Main [template = constants.%Main] {} {}
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: generic interface @IndexWith(constants.%SubscriptType: type, constants.%ElementType: type) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %SubscriptType.patt: type = symbolic_binding_pattern SubscriptType, 0 [symbolic = %SubscriptType.patt (constants.%SubscriptType.patt)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %ElementType.patt: type = symbolic_binding_pattern ElementType, 1 [symbolic = %ElementType.patt (constants.%ElementType.patt)]
+// CHECK:STDOUT:
+// CHECK:STDOUT: !definition:
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:   %At.type: type = fn_type @At, @IndexWith(%SubscriptType, %ElementType) [symbolic = %At.type (constants.%At.type)]
+// CHECK:STDOUT:   %At: @IndexWith.%At.type (%At.type) = struct_value () [symbolic = %At (constants.%At)]
+// CHECK:STDOUT:   %.1: type = assoc_entity_type @IndexWith.%IndexWith.type (%IndexWith.type.2), @IndexWith.%At.type (%At.type) [symbolic = %.1 (constants.%.4)]
+// CHECK:STDOUT:   %.2: @IndexWith.%.1 (%.4) = assoc_entity element0, imports.%import_ref.5 [symbolic = %.2 (constants.%.5)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   interface {
+// CHECK:STDOUT:   !members:
+// CHECK:STDOUT:     .Self = imports.%import_ref.2
+// CHECK:STDOUT:     .At = imports.%import_ref.3
+// CHECK:STDOUT:     witness = (imports.%import_ref.4)
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
 // CHECK:STDOUT: fn @Main() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %.loc16_3: i32 = int_literal 0 [template = constants.%.2]
 // CHECK:STDOUT:   %.loc16_5: i32 = int_literal 1 [template = constants.%.3]
 // CHECK:STDOUT:   %int.make_type_32.loc18: init type = call constants.%Int32() [template = i32]
-// CHECK:STDOUT:   %.loc18_24: i32 = int_literal 2 [template = constants.%.4]
+// CHECK:STDOUT:   %.loc18_24: i32 = int_literal 2 [template = constants.%.6]
 // CHECK:STDOUT:   %.loc18_19.1: type = value_of_initializer %int.make_type_32.loc18 [template = i32]
 // CHECK:STDOUT:   %.loc18_19.2: type = converted %int.make_type_32.loc18, %.loc18_19.1 [template = i32]
-// CHECK:STDOUT:   %.loc18_25: type = array_type %.loc18_24, i32 [template = constants.%.5]
-// CHECK:STDOUT:   %non_tuple.var: ref %.5 = var non_tuple
-// CHECK:STDOUT:   %non_tuple: ref %.5 = bind_name non_tuple, %non_tuple.var
-// CHECK:STDOUT:   %.loc18_30: i32 = int_literal 5 [template = constants.%.7]
-// CHECK:STDOUT:   %.loc18_33: i32 = int_literal 5 [template = constants.%.7]
-// CHECK:STDOUT:   %.loc18_34.1: %.8 = tuple_literal (%.loc18_30, %.loc18_33)
+// CHECK:STDOUT:   %.loc18_25: type = array_type %.loc18_24, i32 [template = constants.%.7]
+// CHECK:STDOUT:   %non_tuple.var: ref %.7 = var non_tuple
+// CHECK:STDOUT:   %non_tuple: ref %.7 = bind_name non_tuple, %non_tuple.var
+// CHECK:STDOUT:   %.loc18_30: i32 = int_literal 5 [template = constants.%.9]
+// CHECK:STDOUT:   %.loc18_33: i32 = int_literal 5 [template = constants.%.9]
+// CHECK:STDOUT:   %.loc18_34.1: %.10 = tuple_literal (%.loc18_30, %.loc18_33)
 // CHECK:STDOUT:   %.loc18_34.2: i32 = int_literal 0 [template = constants.%.2]
 // CHECK:STDOUT:   %.loc18_34.3: ref i32 = array_index %non_tuple.var, %.loc18_34.2
-// CHECK:STDOUT:   %.loc18_34.4: init i32 = initialize_from %.loc18_30 to %.loc18_34.3 [template = constants.%.7]
+// CHECK:STDOUT:   %.loc18_34.4: init i32 = initialize_from %.loc18_30 to %.loc18_34.3 [template = constants.%.9]
 // CHECK:STDOUT:   %.loc18_34.5: i32 = int_literal 1 [template = constants.%.3]
 // CHECK:STDOUT:   %.loc18_34.6: ref i32 = array_index %non_tuple.var, %.loc18_34.5
-// CHECK:STDOUT:   %.loc18_34.7: init i32 = initialize_from %.loc18_33 to %.loc18_34.6 [template = constants.%.7]
-// CHECK:STDOUT:   %.loc18_34.8: init %.5 = array_init (%.loc18_34.4, %.loc18_34.7) to %non_tuple.var [template = constants.%array]
-// CHECK:STDOUT:   %.loc18_35: init %.5 = converted %.loc18_34.1, %.loc18_34.8 [template = constants.%array]
+// CHECK:STDOUT:   %.loc18_34.7: init i32 = initialize_from %.loc18_33 to %.loc18_34.6 [template = constants.%.9]
+// CHECK:STDOUT:   %.loc18_34.8: init %.7 = array_init (%.loc18_34.4, %.loc18_34.7) to %non_tuple.var [template = constants.%array]
+// CHECK:STDOUT:   %.loc18_35: init %.7 = converted %.loc18_34.1, %.loc18_34.8 [template = constants.%array]
 // CHECK:STDOUT:   assign %non_tuple.var, %.loc18_35
 // CHECK:STDOUT:   %int.make_type_32.loc22: init type = call constants.%Int32() [template = i32]
 // CHECK:STDOUT:   %.loc22_14.1: type = value_of_initializer %int.make_type_32.loc22 [template = i32]
 // CHECK:STDOUT:   %.loc22_14.2: type = converted %int.make_type_32.loc22, %.loc22_14.1 [template = i32]
 // CHECK:STDOUT:   %first.var: ref i32 = var first
 // CHECK:STDOUT:   %first: ref i32 = bind_name first, %first.var
-// CHECK:STDOUT:   %non_tuple.ref: ref %.5 = name_ref non_tuple, %non_tuple
+// CHECK:STDOUT:   %non_tuple.ref: ref %.7 = name_ref non_tuple, %non_tuple
 // CHECK:STDOUT:   %.loc22_30: i32 = int_literal 0 [template = constants.%.2]
 // CHECK:STDOUT:   assign %first.var, <error>
 // CHECK:STDOUT:   return
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
+// CHECK:STDOUT: generic fn @At(constants.%SubscriptType: type, constants.%ElementType: type, constants.%Self.1: @IndexWith.%IndexWith.type (%IndexWith.type.2)) {
+// CHECK:STDOUT:   %SubscriptType: type = bind_symbolic_name SubscriptType, 0 [symbolic = %SubscriptType (constants.%SubscriptType)]
+// CHECK:STDOUT:   %ElementType: type = bind_symbolic_name ElementType, 1 [symbolic = %ElementType (constants.%ElementType)]
+// CHECK:STDOUT:   %IndexWith.type: type = interface_type @IndexWith, @IndexWith(%SubscriptType, %ElementType) [symbolic = %IndexWith.type (constants.%IndexWith.type.2)]
+// CHECK:STDOUT:   %Self: %IndexWith.type.2 = bind_symbolic_name Self, 2 [symbolic = %Self (constants.%Self.2)]
+// CHECK:STDOUT:
+// CHECK:STDOUT:   fn[%self.param_patt: @At.%Self (%Self.2)](%subscript.param_patt: @At.%SubscriptType (%SubscriptType)) -> @At.%ElementType (%ElementType);
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
 // CHECK:STDOUT: fn @Int32() -> type = "int.make_type_32";
 // CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(constants.%SubscriptType, constants.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@IndexWith.%SubscriptType, @IndexWith.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @IndexWith(@At.%SubscriptType, @At.%ElementType) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %SubscriptType.patt => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %ElementType.patt => constants.%ElementType
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: specific @At(constants.%SubscriptType, constants.%ElementType, constants.%Self.1) {
+// CHECK:STDOUT:   %SubscriptType => constants.%SubscriptType
+// CHECK:STDOUT:   %ElementType => constants.%ElementType
+// CHECK:STDOUT:   %IndexWith.type => constants.%IndexWith.type.2
+// CHECK:STDOUT:   %Self => constants.%Self.1
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
diff --git a/toolchain/check/testdata/tuple/access/fail_out_of_bound_access.carbon b/toolchain/check/testdata/tuple/access/fail_out_of_bound_access.carbon
index abcb9fb73a5c..b9c3a2659196 100644
--- a/toolchain/check/testdata/tuple/access/fail_out_of_bound_access.carbon
+++ b/toolchain/check/testdata/tuple/access/fail_out_of_bound_access.carbon
@@ -37,6 +37,7 @@ var b: i32 = a.2;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/fail_out_of_bound_not_literal.carbon b/toolchain/check/testdata/tuple/access/fail_out_of_bound_not_literal.carbon
index b073d93fd6f2..f9ad35262cfe 100644
--- a/toolchain/check/testdata/tuple/access/fail_out_of_bound_not_literal.carbon
+++ b/toolchain/check/testdata/tuple/access/fail_out_of_bound_not_literal.carbon
@@ -39,6 +39,7 @@ var b: i32 = a.({.index = 2}.index);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/index_not_literal.carbon b/toolchain/check/testdata/tuple/access/index_not_literal.carbon
index 562413656b06..e315ed4de5f4 100644
--- a/toolchain/check/testdata/tuple/access/index_not_literal.carbon
+++ b/toolchain/check/testdata/tuple/access/index_not_literal.carbon
@@ -36,6 +36,7 @@ var b: i32 = a.({.index = 1}.index);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/access/return_value_access.carbon b/toolchain/check/testdata/tuple/access/return_value_access.carbon
index 5f71c473b805..6898804ed34a 100644
--- a/toolchain/check/testdata/tuple/access/return_value_access.carbon
+++ b/toolchain/check/testdata/tuple/access/return_value_access.carbon
@@ -38,6 +38,7 @@ fn Run() -> i32 {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/fail_assign_nested.carbon b/toolchain/check/testdata/tuple/fail_assign_nested.carbon
index fa39231d5634..729151e04f6c 100644
--- a/toolchain/check/testdata/tuple/fail_assign_nested.carbon
+++ b/toolchain/check/testdata/tuple/fail_assign_nested.carbon
@@ -44,6 +44,7 @@ var x: ((i32, i32), (i32, i32)) = ((1, 2, 3), (4, 5, 6));
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/fail_element_type_mismatch.carbon b/toolchain/check/testdata/tuple/fail_element_type_mismatch.carbon
index 8d42b46d0dcd..a69fd3cfa654 100644
--- a/toolchain/check/testdata/tuple/fail_element_type_mismatch.carbon
+++ b/toolchain/check/testdata/tuple/fail_element_type_mismatch.carbon
@@ -56,6 +56,7 @@ var x: (i32, i32) = (2, 65.89);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/fail_nested_incomplete.carbon b/toolchain/check/testdata/tuple/fail_nested_incomplete.carbon
index 3be959802825..148f354bd5fe 100644
--- a/toolchain/check/testdata/tuple/fail_nested_incomplete.carbon
+++ b/toolchain/check/testdata/tuple/fail_nested_incomplete.carbon
@@ -41,6 +41,7 @@ var p: Incomplete* = &t[1];
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/fail_too_few_element.carbon b/toolchain/check/testdata/tuple/fail_too_few_element.carbon
index 5976a3f486e7..4364cb086d18 100644
--- a/toolchain/check/testdata/tuple/fail_too_few_element.carbon
+++ b/toolchain/check/testdata/tuple/fail_too_few_element.carbon
@@ -34,6 +34,7 @@ var x: (i32, i32) = (2, );
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/fail_type_assign.carbon b/toolchain/check/testdata/tuple/fail_type_assign.carbon
index e53265e9bb48..d7c34b7fe781 100644
--- a/toolchain/check/testdata/tuple/fail_type_assign.carbon
+++ b/toolchain/check/testdata/tuple/fail_type_assign.carbon
@@ -52,6 +52,7 @@ var x: (i32, ) = (i32, );
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/fail_value_as_type.carbon b/toolchain/check/testdata/tuple/fail_value_as_type.carbon
index 953e86d1018f..97d5e8d1091a 100644
--- a/toolchain/check/testdata/tuple/fail_value_as_type.carbon
+++ b/toolchain/check/testdata/tuple/fail_value_as_type.carbon
@@ -49,6 +49,7 @@ var x: (1, );
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/import.carbon b/toolchain/check/testdata/tuple/import.carbon
index c87f03192543..1a3759232506 100644
--- a/toolchain/check/testdata/tuple/import.carbon
+++ b/toolchain/check/testdata/tuple/import.carbon
@@ -100,6 +100,7 @@ var c_bad: C((3, 4)) = F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -287,6 +288,7 @@ var c_bad: C((3, 4)) = F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -458,6 +460,7 @@ var c_bad: C((3, 4)) = F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -576,6 +579,7 @@ var c_bad: C((3, 4)) = F();
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/nested_tuple.carbon b/toolchain/check/testdata/tuple/nested_tuple.carbon
index 3388635d6e3b..bb9bffabe034 100644
--- a/toolchain/check/testdata/tuple/nested_tuple.carbon
+++ b/toolchain/check/testdata/tuple/nested_tuple.carbon
@@ -38,6 +38,7 @@ var x: ((i32, i32), i32) = ((12, 76), 6);
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/nested_tuple_in_place.carbon b/toolchain/check/testdata/tuple/nested_tuple_in_place.carbon
index b845b4c916b9..3f277cca8075 100644
--- a/toolchain/check/testdata/tuple/nested_tuple_in_place.carbon
+++ b/toolchain/check/testdata/tuple/nested_tuple_in_place.carbon
@@ -53,6 +53,7 @@ fn H() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/one_element.carbon b/toolchain/check/testdata/tuple/one_element.carbon
index 52a63f4eb89b..2bdea47b79c9 100644
--- a/toolchain/check/testdata/tuple/one_element.carbon
+++ b/toolchain/check/testdata/tuple/one_element.carbon
@@ -31,6 +31,7 @@ var y: (i32,) = x;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/tuple/two_elements.carbon b/toolchain/check/testdata/tuple/two_elements.carbon
index 1c42fa66fc4d..36a7cacd0669 100644
--- a/toolchain/check/testdata/tuple/two_elements.carbon
+++ b/toolchain/check/testdata/tuple/two_elements.carbon
@@ -36,6 +36,7 @@ var y: (i32, i32) = x;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/var/fail_not_copyable.carbon b/toolchain/check/testdata/var/fail_not_copyable.carbon
index 3b607940e03b..178a24a04a79 100644
--- a/toolchain/check/testdata/var/fail_not_copyable.carbon
+++ b/toolchain/check/testdata/var/fail_not_copyable.carbon
@@ -48,6 +48,7 @@ fn F(x: X) {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/var/fail_storage_is_literal.carbon b/toolchain/check/testdata/var/fail_storage_is_literal.carbon
index ad134336e7f1..5e7c44477c91 100644
--- a/toolchain/check/testdata/var/fail_storage_is_literal.carbon
+++ b/toolchain/check/testdata/var/fail_storage_is_literal.carbon
@@ -52,6 +52,7 @@ fn Main() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/var/fail_todo_control_flow_init.carbon b/toolchain/check/testdata/var/fail_todo_control_flow_init.carbon
index ffd5f2cf149f..51e41be377ca 100644
--- a/toolchain/check/testdata/var/fail_todo_control_flow_init.carbon
+++ b/toolchain/check/testdata/var/fail_todo_control_flow_init.carbon
@@ -74,6 +74,7 @@ var y2: bool = false or true;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/where_expr/constraints.carbon b/toolchain/check/testdata/where_expr/constraints.carbon
index 2923ad213498..3f73c06e227f 100644
--- a/toolchain/check/testdata/where_expr/constraints.carbon
+++ b/toolchain/check/testdata/where_expr/constraints.carbon
@@ -203,6 +203,7 @@ let B: type where .Self impls A = D;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -374,6 +375,7 @@ let B: type where .Self impls A = D;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -546,6 +548,7 @@ let B: type where .Self impls A = D;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -739,6 +742,7 @@ let B: type where .Self impls A = D;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -909,6 +913,7 @@ let B: type where .Self impls A = D;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1056,6 +1061,7 @@ let B: type where .Self impls A = D;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1188,6 +1194,7 @@ let B: type where .Self impls A = D;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1287,6 +1294,7 @@ let B: type where .Self impls A = D;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -1486,6 +1494,7 @@ let B: type where .Self impls A = D;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/where_expr/designator.carbon b/toolchain/check/testdata/where_expr/designator.carbon
index 8079321336ff..5e72667f9310 100644
--- a/toolchain/check/testdata/where_expr/designator.carbon
+++ b/toolchain/check/testdata/where_expr/designator.carbon
@@ -117,6 +117,7 @@ class D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -247,6 +248,7 @@ class D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -316,6 +318,7 @@ class D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -364,6 +367,7 @@ class D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -412,6 +416,7 @@ class D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -467,6 +472,7 @@ class D {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/where_expr/fail_not_facet.carbon b/toolchain/check/testdata/where_expr/fail_not_facet.carbon
index 4fd94346119f..57c1d9671920 100644
--- a/toolchain/check/testdata/where_expr/fail_not_facet.carbon
+++ b/toolchain/check/testdata/where_expr/fail_not_facet.carbon
@@ -69,6 +69,7 @@ var v: e where .x = 3;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -138,6 +139,7 @@ var v: e where .x = 3;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
@@ -195,6 +197,7 @@ var v: e where .x = 3;
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/where_expr/non_generic.carbon b/toolchain/check/testdata/where_expr/non_generic.carbon
index 1bad09dbd92d..3de2111806d5 100644
--- a/toolchain/check/testdata/where_expr/non_generic.carbon
+++ b/toolchain/check/testdata/where_expr/non_generic.carbon
@@ -36,6 +36,7 @@ fn NotGenericF(U: I where .T == i32) {}
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/while/break_continue.carbon b/toolchain/check/testdata/while/break_continue.carbon
index d2968636f3c1..08ef887cc9f6 100644
--- a/toolchain/check/testdata/while/break_continue.carbon
+++ b/toolchain/check/testdata/while/break_continue.carbon
@@ -64,6 +64,7 @@ fn While() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/while/fail_bad_condition.carbon b/toolchain/check/testdata/while/fail_bad_condition.carbon
index 3831f1a1e548..3c9512218194 100644
--- a/toolchain/check/testdata/while/fail_bad_condition.carbon
+++ b/toolchain/check/testdata/while/fail_bad_condition.carbon
@@ -53,6 +53,7 @@ fn While() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/while/fail_break_continue.carbon b/toolchain/check/testdata/while/fail_break_continue.carbon
index 913d7b5d6ce1..d6d3e5f16d50 100644
--- a/toolchain/check/testdata/while/fail_break_continue.carbon
+++ b/toolchain/check/testdata/while/fail_break_continue.carbon
@@ -50,6 +50,7 @@ fn While() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/while/unreachable_end.carbon b/toolchain/check/testdata/while/unreachable_end.carbon
index f05d1a8a45b2..c85101df623b 100644
--- a/toolchain/check/testdata/while/unreachable_end.carbon
+++ b/toolchain/check/testdata/while/unreachable_end.carbon
@@ -49,6 +49,7 @@ fn While() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool
diff --git a/toolchain/check/testdata/while/while.carbon b/toolchain/check/testdata/while/while.carbon
index 3fa9c8b30178..5a57d423e664 100644
--- a/toolchain/check/testdata/while/while.carbon
+++ b/toolchain/check/testdata/while/while.carbon
@@ -48,6 +48,7 @@ fn While() {
 // CHECK:STDOUT:     import Core//prelude/types
 // CHECK:STDOUT:     import Core//prelude/operators/arithmetic
 // CHECK:STDOUT:     import Core//prelude/operators/as
+// CHECK:STDOUT:     import Core//prelude/operators/index
 // CHECK:STDOUT:     import Core//prelude/operators/bitwise
 // CHECK:STDOUT:     import Core//prelude/operators/comparison
 // CHECK:STDOUT:     import Core//prelude/types/bool