diff --git a/toolchain/check/import_cpp.cpp b/toolchain/check/import_cpp.cpp
index f2921bc6a941..cee1da4272ec 100644
--- a/toolchain/check/import_cpp.cpp
+++ b/toolchain/check/import_cpp.cpp
@@ -497,6 +497,37 @@ static auto BuildClassDecl(Context& context,
   return {class_decl.class_id, context.types().GetAsTypeInstId(class_decl_id)};
 }
 
+// Determines the Carbon inheritance kind to use for a C++ class definition.
+static auto GetInheritanceKind(clang::CXXRecordDecl* class_def)
+    -> SemIR::Class::InheritanceKind {
+  if (class_def->isUnion()) {
+    // Treat all unions as final classes to match their C++ semantics. While we
+    // could support this, the author of a C++ union has no way to mark their
+    // type as `final` to prevent it, and so we assume the intent was to
+    // disallow inheritance.
+    return SemIR::Class::Final;
+  }
+
+  if (class_def->hasAttr<clang::FinalAttr>()) {
+    // The class is final in C++; don't allow Carbon types to derive from it.
+    // Note that such a type might also be abstract in C++; we treat final as
+    // taking precedence.
+    //
+    // We could also treat classes with a final destructor as being final, as
+    // Clang does when determining whether a class is "effectively final", but
+    // to keep our rules simpler we do not.
+    return SemIR::Class::Final;
+  }
+
+  if (class_def->isAbstract()) {
+    // If the class has any abstract members, it's abstract.
+    return SemIR::Class::Abstract;
+  }
+
+  // Allow inheritance from any other C++ class type.
+  return SemIR::Class::Base;
+}
+
 // Checks that the specified finished class definition is valid and builds and
 // returns a corresponding complete type witness instruction.
 // TODO: Remove recursion into mapping field types.
@@ -685,6 +716,8 @@ static auto BuildClassDefinition(Context& context,
 
   context.inst_block_stack().Push();
 
+  class_info.inheritance_kind = GetInheritanceKind(clang_def);
+
   // Compute the class's object representation.
   auto object_repr_id = ImportClassObjectRepr(
       context, class_id, import_ir_inst_id, class_inst_id, clang_def);
diff --git a/toolchain/check/testdata/interop/cpp/class/abstract.carbon b/toolchain/check/testdata/interop/cpp/class/abstract.carbon
new file mode 100644
index 000000000000..6b93cd5a515a
--- /dev/null
+++ b/toolchain/check/testdata/interop/cpp/class/abstract.carbon
@@ -0,0 +1,138 @@
+// 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
+//
+// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/destroy.carbon
+// EXTRA-ARGS: --clang-arg=-Wno-abstract-final-class
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/interop/cpp/class/abstract.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/class/abstract.carbon
+
+// --- abstract.h
+
+struct A {
+  virtual void f() = 0;
+};
+
+// --- derive_base_from_abstract.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "abstract.h";
+
+base class B {
+  extend base: Cpp.A;
+}
+
+// --- todo_fail_derive_final_from_abstract.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "abstract.h";
+
+class C {
+  // TODO: We should reject this because `f` is not implemented.
+  extend base: Cpp.A;
+}
+
+// --- fail_todo_impl_abstract_member.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "abstract.h";
+
+class C {
+  extend base: Cpp.A;
+  // CHECK:STDERR: fail_todo_impl_abstract_member.carbon:[[@LINE+4]]:3: error: impl without compatible virtual in base class [ImplWithoutVirtualInBase]
+  // CHECK:STDERR:   impl fn f[addr self: Self*]() {}
+  // CHECK:STDERR:   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  impl fn f[addr self: Self*]() {}
+}
+
+// --- abstract_final.h
+
+// C++ allows a class to be both abstract and final.
+struct AbstractFinal final {
+  virtual void f() = 0;
+};
+
+// --- fail_derive_from_abstract_final.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "abstract_final.h";
+
+class C {
+  // CHECK:STDERR: fail_derive_from_abstract_final.carbon:[[@LINE+4]]:16: error: deriving from final type `AbstractFinal`; base type must be an `abstract` or `base` class [BaseIsFinal]
+  // CHECK:STDERR:   extend base: Cpp.AbstractFinal;
+  // CHECK:STDERR:                ^~~~~~~~~~~~~~~~~
+  // CHECK:STDERR:
+  extend base: Cpp.AbstractFinal;
+}
+
+// --- use_abstract_final.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "abstract_final.h";
+
+// We model an abstract final class as being final, rather than abstract. This
+// prevents inheritance from it, and there's no actual way to initialize an
+// instance of the type, but that does not prevent defining a function that
+// returns the type by value. Make sure that doesn't crash.
+//@dump-sem-ir-begin
+fn F() -> Cpp.AbstractFinal {
+  return F();
+}
+//@dump-sem-ir-end
+
+// CHECK:STDOUT: --- use_abstract_final.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %AbstractFinal: type = class_type @AbstractFinal [concrete]
+// CHECK:STDOUT:   %pattern_type.2e0: type = pattern_type %AbstractFinal [concrete]
+// CHECK:STDOUT:   %F.type: type = fn_type @F [concrete]
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %F: %F.type = struct_value () [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.type.4da: type = fn_type @T.as.Destroy.impl.Op, @T.as.Destroy.impl(%AbstractFinal) [concrete]
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.0fa: %T.as.Destroy.impl.Op.type.4da = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.d4c: type = ptr_type %AbstractFinal [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .AbstractFinal = %AbstractFinal.decl
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %AbstractFinal.decl: type = class_decl @AbstractFinal [concrete = constants.%AbstractFinal] {} {}
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: file {
+// CHECK:STDOUT:   %F.decl: %F.type = fn_decl @F [concrete = constants.%F] {
+// CHECK:STDOUT:     %return.patt: %pattern_type.2e0 = return_slot_pattern [concrete]
+// CHECK:STDOUT:     %return.param_patt: %pattern_type.2e0 = out_param_pattern %return.patt, call_param0 [concrete]
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %AbstractFinal.ref: type = name_ref AbstractFinal, imports.%AbstractFinal.decl [concrete = constants.%AbstractFinal]
+// CHECK:STDOUT:     %return.param: ref %AbstractFinal = out_param call_param0
+// CHECK:STDOUT:     %return: ref %AbstractFinal = return_slot %return.param
+// CHECK:STDOUT:   }
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() -> %return.param: %AbstractFinal {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %F.ref: %F.type = name_ref F, file.%F.decl [concrete = constants.%F]
+// CHECK:STDOUT:   %.loc11: ref %AbstractFinal = splice_block %return {}
+// CHECK:STDOUT:   %F.call: init %AbstractFinal = call %F.ref() to %.loc11
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.bound: <bound method> = bound_method %.loc11, constants.%T.as.Destroy.impl.Op.0fa
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %bound_method: <bound method> = bound_method %.loc11, %T.as.Destroy.impl.Op.specific_fn
+// CHECK:STDOUT:   %addr: %ptr.d4c = addr_of %.loc11
+// CHECK:STDOUT:   %T.as.Destroy.impl.Op.call: init %empty_tuple.type = call %bound_method(%addr)
+// CHECK:STDOUT:   return %F.call to %return
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
diff --git a/toolchain/check/testdata/interop/cpp/class/base.carbon b/toolchain/check/testdata/interop/cpp/class/base.carbon
index bee72302efe4..718624b08048 100644
--- a/toolchain/check/testdata/interop/cpp/class/base.carbon
+++ b/toolchain/check/testdata/interop/cpp/class/base.carbon
@@ -3,7 +3,6 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 // INCLUDE-FILE: toolchain/testing/testdata/min_prelude/primitives.carbon
-// EXTRA-ARGS: --dump-sem-ir-ranges=ignore
 //
 // AUTOUPDATE
 // TIP: To test this file alone, run:
@@ -182,16 +181,47 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
   return p;
 }
 
+// --- final.h
+
+struct A final {};
+
+// --- fail_derive_from_final.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "final.h";
+
+class B {
+  // CHECK:STDERR: fail_derive_from_final.carbon:[[@LINE+4]]:16: error: deriving from final type `A`; base type must be an `abstract` or `base` class [BaseIsFinal]
+  // CHECK:STDERR:   extend base: Cpp.A;
+  // CHECK:STDERR:                ^~~~~
+  // CHECK:STDERR:
+  extend base: Cpp.A;
+}
+
+// --- union.h
+
+union U {};
+
+// --- fail_derive_from_union.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "union.h";
+
+class V {
+  // CHECK:STDERR: fail_derive_from_union.carbon:[[@LINE+4]]:16: error: deriving from final type `U`; base type must be an `abstract` or `base` class [BaseIsFinal]
+  // CHECK:STDERR:   extend base: Cpp.U;
+  // CHECK:STDERR:                ^~~~~
+  // CHECK:STDERR:
+  extend base: Cpp.U;
+}
+
 // CHECK:STDOUT: --- use_derived_to_base_conversion.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %Derived: type = class_type @Derived [concrete]
 // CHECK:STDOUT:   %Base: type = class_type @Base [concrete]
-// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
-// CHECK:STDOUT:   %complete_type.357: <witness> = complete_type_witness %empty_struct_type [concrete]
-// CHECK:STDOUT:   %Derived.elem: type = unbound_element_type %Derived, %Base [concrete]
-// CHECK:STDOUT:   %.52d: type = custom_layout_type {size=1, align=1, .base@0: %Base} [concrete]
-// CHECK:STDOUT:   %complete_type.fd1: <witness> = complete_type_witness %.52d [concrete]
 // CHECK:STDOUT:   %ptr.ddb: type = ptr_type %Derived [concrete]
 // CHECK:STDOUT:   %pattern_type.5c8: type = pattern_type %ptr.ddb [concrete]
 // CHECK:STDOUT:   %ptr.fb2: type = ptr_type %Base [concrete]
@@ -199,7 +229,6 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:   %ConvertPtr.type: type = fn_type @ConvertPtr [concrete]
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
 // CHECK:STDOUT:   %ConvertPtr: %ConvertPtr.type = struct_value () [concrete]
-// CHECK:STDOUT:   %pattern_type.a3a: type = pattern_type %Base [concrete]
 // CHECK:STDOUT:   %AcceptVal.type: type = fn_type @AcceptVal [concrete]
 // CHECK:STDOUT:   %AcceptVal: %AcceptVal.type = struct_value () [concrete]
 // CHECK:STDOUT:   %pattern_type.5de: type = pattern_type %Derived [concrete]
@@ -208,10 +237,6 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [concrete] {
-// CHECK:STDOUT:     import Core//prelude
-// CHECK:STDOUT:     import Core//prelude/...
-// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .Derived = %Derived.decl
 // CHECK:STDOUT:     .Base = %Base.decl
@@ -222,17 +247,6 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {
-// CHECK:STDOUT:   package: <namespace> = namespace [concrete] {
-// CHECK:STDOUT:     .Core = imports.%Core
-// CHECK:STDOUT:     .Cpp = imports.%Cpp
-// CHECK:STDOUT:     .ConvertPtr = %ConvertPtr.decl
-// CHECK:STDOUT:     .AcceptVal = %AcceptVal.decl
-// CHECK:STDOUT:     .ConvertVal = %ConvertVal.decl
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import = import Core
-// CHECK:STDOUT:   %Cpp.import_cpp = import_cpp {
-// CHECK:STDOUT:     import Cpp "derived_to_base_conversion.h"
-// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %ConvertPtr.decl: %ConvertPtr.type = fn_decl @ConvertPtr [concrete = constants.%ConvertPtr] {
 // CHECK:STDOUT:     %d.patt: %pattern_type.5c8 = binding_pattern d [concrete]
 // CHECK:STDOUT:     %d.param_patt: %pattern_type.5c8 = value_param_pattern %d.patt, call_param0 [concrete]
@@ -252,17 +266,6 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:     %return.param: ref %ptr.fb2 = out_param call_param1
 // CHECK:STDOUT:     %return: ref %ptr.fb2 = return_slot %return.param
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %AcceptVal.decl: %AcceptVal.type = fn_decl @AcceptVal [concrete = constants.%AcceptVal] {
-// CHECK:STDOUT:     %b.patt: %pattern_type.a3a = binding_pattern b [concrete]
-// CHECK:STDOUT:     %b.param_patt: %pattern_type.a3a = value_param_pattern %b.patt, call_param0 [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %b.param: %Base = value_param call_param0
-// CHECK:STDOUT:     %.loc12: type = splice_block %Base.ref [concrete = constants.%Base] {
-// CHECK:STDOUT:       %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:       %Base.ref: type = name_ref Base, imports.%Base.decl [concrete = constants.%Base]
-// CHECK:STDOUT:     }
-// CHECK:STDOUT:     %b: %Base = bind_name b, %b.param
-// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %ConvertVal.decl: %ConvertVal.type = fn_decl @ConvertVal [concrete = constants.%ConvertVal] {
 // CHECK:STDOUT:     %d.patt: %pattern_type.5de = binding_pattern d [concrete]
 // CHECK:STDOUT:     %d.param_patt: %pattern_type.5de = value_param_pattern %d.patt, call_param0 [concrete]
@@ -276,27 +279,6 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: class @Derived {
-// CHECK:STDOUT:   %.1: %Derived.elem = base_decl imports.%Base.decl, element0 [concrete]
-// CHECK:STDOUT:   %.2: type = custom_layout_type {size=1, align=1, .base@0: %Base} [concrete = constants.%.52d]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %.2 [concrete = constants.%complete_type.fd1]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%Derived
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @Base {
-// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete = constants.%empty_struct_type]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %empty_struct_type [concrete = constants.%complete_type.357]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%Base
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConvertPtr(%d.param: %ptr.ddb) -> %ptr.fb2 {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %d.ref: %ptr.ddb = name_ref d, %d
@@ -307,8 +289,6 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:   return %.loc8_11.3
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: fn @AcceptVal(%b.param: %Base);
-// CHECK:STDOUT:
 // CHECK:STDOUT: fn @ConvertVal(%d.param: %Derived) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %AcceptVal.ref: %AcceptVal.type = name_ref AcceptVal, file.%AcceptVal.decl [concrete = constants.%AcceptVal]
@@ -323,27 +303,16 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT: --- use_static_member.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %MyF.type: type = fn_type @MyF [concrete]
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
-// CHECK:STDOUT:   %MyF: %MyF.type = struct_value () [concrete]
 // CHECK:STDOUT:   %Base: type = class_type @Base [concrete]
-// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
-// CHECK:STDOUT:   %complete_type.357: <witness> = complete_type_witness %empty_struct_type [concrete]
 // CHECK:STDOUT:   %Base.base_fn.type: type = fn_type @Base.base_fn [concrete]
 // CHECK:STDOUT:   %Base.base_fn: %Base.base_fn.type = struct_value () [concrete]
 // CHECK:STDOUT:   %Derived: type = class_type @Derived [concrete]
-// CHECK:STDOUT:   %Derived.elem: type = unbound_element_type %Derived, %Base [concrete]
-// CHECK:STDOUT:   %.52d: type = custom_layout_type {size=1, align=1, .base@0: %Base} [concrete]
-// CHECK:STDOUT:   %complete_type.fd1: <witness> = complete_type_witness %.52d [concrete]
 // CHECK:STDOUT:   %Derived.derived_fn.type: type = fn_type @Derived.derived_fn [concrete]
 // CHECK:STDOUT:   %Derived.derived_fn: %Derived.derived_fn.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [concrete] {
-// CHECK:STDOUT:     import Core//prelude
-// CHECK:STDOUT:     import Core//prelude/...
-// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .Base = %Base.decl
 // CHECK:STDOUT:     .Derived = %Derived.decl
@@ -355,43 +324,6 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:   %Derived.derived_fn.decl: %Derived.derived_fn.type = fn_decl @Derived.derived_fn [concrete = constants.%Derived.derived_fn] {} {}
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: file {
-// CHECK:STDOUT:   package: <namespace> = namespace [concrete] {
-// CHECK:STDOUT:     .Core = imports.%Core
-// CHECK:STDOUT:     .Cpp = imports.%Cpp
-// CHECK:STDOUT:     .MyF = %MyF.decl
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import = import Core
-// CHECK:STDOUT:   %Cpp.import_cpp = import_cpp {
-// CHECK:STDOUT:     import Cpp "static_member.h"
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %MyF.decl: %MyF.type = fn_decl @MyF [concrete = constants.%MyF] {} {}
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @Base {
-// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete = constants.%empty_struct_type]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %empty_struct_type [concrete = constants.%complete_type.357]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%Base
-// CHECK:STDOUT:   .base_fn = imports.%Base.base_fn.decl
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @Derived {
-// CHECK:STDOUT:   %.1: %Derived.elem = base_decl imports.%Base.decl, element0 [concrete]
-// CHECK:STDOUT:   %.2: type = custom_layout_type {size=1, align=1, .base@0: %Base} [concrete = constants.%.52d]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %.2 [concrete = constants.%complete_type.fd1]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%Derived
-// CHECK:STDOUT:   .base_fn = imports.%Base.base_fn.decl
-// CHECK:STDOUT:   .derived_fn = imports.%Derived.derived_fn.decl
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
 // CHECK:STDOUT: fn @MyF() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref.loc8: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
@@ -406,43 +338,20 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:   %Derived.ref.loc10: type = name_ref Derived, imports.%Derived.decl [concrete = constants.%Derived]
 // CHECK:STDOUT:   %derived_fn.ref: %Derived.derived_fn.type = name_ref derived_fn, imports.%Derived.derived_fn.decl [concrete = constants.%Derived.derived_fn]
 // CHECK:STDOUT:   %Derived.derived_fn.call: init %empty_tuple.type = call %derived_fn.ref()
-// CHECK:STDOUT:   return
+// CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: fn @Base.base_fn();
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @Derived.derived_fn();
-// CHECK:STDOUT:
 // CHECK:STDOUT: --- use_base_field.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %Derived: type = class_type @Derived [concrete]
 // CHECK:STDOUT:   %Base: type = class_type @Base [concrete]
 // CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
-// CHECK:STDOUT:   %Int.type: type = generic_class_type @Int [concrete]
-// CHECK:STDOUT:   %Int.generic: %Int.type = struct_value () [concrete]
 // CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
 // CHECK:STDOUT:   %Base.elem: type = unbound_element_type %Base, %i32 [concrete]
-// CHECK:STDOUT:   %.807: type = custom_layout_type {size=8, align=4, .a@0: %i32, .b@4: %i32} [concrete]
-// CHECK:STDOUT:   %complete_type.e3e: <witness> = complete_type_witness %.807 [concrete]
-// CHECK:STDOUT:   %Derived.elem.b4e: type = unbound_element_type %Derived, %Base [concrete]
-// CHECK:STDOUT:   %Derived.elem.16d: type = unbound_element_type %Derived, %i32 [concrete]
-// CHECK:STDOUT:   %.f26: type = custom_layout_type {size=12, align=4, .base@0: %Base, .b@8: %i32} [concrete]
-// CHECK:STDOUT:   %complete_type.0bc: <witness> = complete_type_witness %.f26 [concrete]
-// CHECK:STDOUT:   %pattern_type.5de: type = pattern_type %Derived [concrete]
-// CHECK:STDOUT:   %pattern_type.7ce: type = pattern_type %i32 [concrete]
-// CHECK:STDOUT:   %AccessDirect.type: type = fn_type @AccessDirect [concrete]
-// CHECK:STDOUT:   %AccessDirect: %AccessDirect.type = struct_value () [concrete]
-// CHECK:STDOUT:   %AccessQualified.type: type = fn_type @AccessQualified [concrete]
-// CHECK:STDOUT:   %AccessQualified: %AccessQualified.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [concrete] {
-// CHECK:STDOUT:     .Int = %Core.Int
-// CHECK:STDOUT:     import Core//prelude
-// CHECK:STDOUT:     import Core//prelude/...
-// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .Derived = %Derived.decl
 // CHECK:STDOUT:     .Base = %Base.decl
@@ -450,86 +359,6 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Derived.decl: type = class_decl @Derived [concrete = constants.%Derived] {} {}
 // CHECK:STDOUT:   %Base.decl: type = class_decl @Base [concrete = constants.%Base] {} {}
-// CHECK:STDOUT:   %Core.Int: %Int.type = import_ref Core//prelude/parts/int, Int, loaded [concrete = constants.%Int.generic]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: file {
-// CHECK:STDOUT:   package: <namespace> = namespace [concrete] {
-// CHECK:STDOUT:     .Core = imports.%Core
-// CHECK:STDOUT:     .Cpp = imports.%Cpp
-// CHECK:STDOUT:     .AccessDirect = %AccessDirect.decl
-// CHECK:STDOUT:     .AccessQualified = %AccessQualified.decl
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import = import Core
-// CHECK:STDOUT:   %Cpp.import_cpp = import_cpp {
-// CHECK:STDOUT:     import Cpp "base_field.h"
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %AccessDirect.decl: %AccessDirect.type = fn_decl @AccessDirect [concrete = constants.%AccessDirect] {
-// CHECK:STDOUT:     %d.patt: %pattern_type.5de = binding_pattern d [concrete]
-// CHECK:STDOUT:     %d.param_patt: %pattern_type.5de = value_param_pattern %d.patt, call_param0 [concrete]
-// CHECK:STDOUT:     %return.patt: %pattern_type.7ce = return_slot_pattern [concrete]
-// CHECK:STDOUT:     %return.param_patt: %pattern_type.7ce = out_param_pattern %return.patt, call_param1 [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %int_32: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:     %i32: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:     %d.param: %Derived = value_param call_param0
-// CHECK:STDOUT:     %.loc6: type = splice_block %Derived.ref [concrete = constants.%Derived] {
-// CHECK:STDOUT:       %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:       %Derived.ref: type = name_ref Derived, imports.%Derived.decl [concrete = constants.%Derived]
-// CHECK:STDOUT:     }
-// CHECK:STDOUT:     %d: %Derived = bind_name d, %d.param
-// CHECK:STDOUT:     %return.param: ref %i32 = out_param call_param1
-// CHECK:STDOUT:     %return: ref %i32 = return_slot %return.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %AccessQualified.decl: %AccessQualified.type = fn_decl @AccessQualified [concrete = constants.%AccessQualified] {
-// CHECK:STDOUT:     %d.patt: %pattern_type.5de = binding_pattern d [concrete]
-// CHECK:STDOUT:     %d.param_patt: %pattern_type.5de = value_param_pattern %d.patt, call_param0 [concrete]
-// CHECK:STDOUT:     %return.patt: %pattern_type.7ce = return_slot_pattern [concrete]
-// CHECK:STDOUT:     %return.param_patt: %pattern_type.7ce = out_param_pattern %return.patt, call_param1 [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %int_32: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:     %i32: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:     %d.param: %Derived = value_param call_param0
-// CHECK:STDOUT:     %.loc12: type = splice_block %Derived.ref [concrete = constants.%Derived] {
-// CHECK:STDOUT:       %Cpp.ref.loc12: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:       %Derived.ref: type = name_ref Derived, imports.%Derived.decl [concrete = constants.%Derived]
-// CHECK:STDOUT:     }
-// CHECK:STDOUT:     %d: %Derived = bind_name d, %d.param
-// CHECK:STDOUT:     %return.param: ref %i32 = out_param call_param1
-// CHECK:STDOUT:     %return: ref %i32 = return_slot %return.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @Derived {
-// CHECK:STDOUT:   %.1: %Derived.elem.b4e = base_decl imports.%Base.decl, element0 [concrete]
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:   %.2: %Derived.elem.16d = field_decl b, element1 [concrete]
-// CHECK:STDOUT:   %.3: type = custom_layout_type {size=12, align=4, .base@0: %Base, .b@8: %i32} [concrete = constants.%.f26]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %.3 [concrete = constants.%complete_type.0bc]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%Derived
-// CHECK:STDOUT:   .a = @Base.%.1
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @Base {
-// CHECK:STDOUT:   %int_32.1: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:   %i32.1: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:   %.1: %Base.elem = field_decl a, element0 [concrete]
-// CHECK:STDOUT:   %int_32.2: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:   %i32.2: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:   %.2: %Base.elem = field_decl b, element1 [concrete]
-// CHECK:STDOUT:   %.3: type = custom_layout_type {size=8, align=4, .a@0: %i32, .b@4: %i32} [concrete = constants.%.807]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %.3 [concrete = constants.%complete_type.e3e]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%Base
-// CHECK:STDOUT:   .b = %.2
-// CHECK:STDOUT:   import Cpp//...
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @AccessDirect(%d.param: %Derived) -> %i32 {
@@ -561,29 +390,14 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %Derived: type = class_type @Derived [concrete]
 // CHECK:STDOUT:   %Base: type = class_type @Base [concrete]
-// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
-// CHECK:STDOUT:   %complete_type.357: <witness> = complete_type_witness %empty_struct_type [concrete]
-// CHECK:STDOUT:   %Derived.elem: type = unbound_element_type %Derived, %Base [concrete]
-// CHECK:STDOUT:   %.52d: type = custom_layout_type {size=1, align=1, .base@0: %Base} [concrete]
-// CHECK:STDOUT:   %complete_type.fd1: <witness> = complete_type_witness %.52d [concrete]
-// CHECK:STDOUT:   %pattern_type.5de: type = pattern_type %Derived [concrete]
-// CHECK:STDOUT:   %CallDirect.type: type = fn_type @CallDirect [concrete]
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
-// CHECK:STDOUT:   %CallDirect: %CallDirect.type = struct_value () [concrete]
-// CHECK:STDOUT:   %pattern_type.a3a: type = pattern_type %Base [concrete]
 // CHECK:STDOUT:   %Base.f.type: type = fn_type @Base.f [concrete]
 // CHECK:STDOUT:   %Base.f: %Base.f.type = struct_value () [concrete]
-// CHECK:STDOUT:   %CallQualified.type: type = fn_type @CallQualified [concrete]
-// CHECK:STDOUT:   %CallQualified: %CallQualified.type = struct_value () [concrete]
 // CHECK:STDOUT:   %Base.g.type: type = fn_type @Base.g [concrete]
 // CHECK:STDOUT:   %Base.g: %Base.g.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [concrete] {
-// CHECK:STDOUT:     import Core//prelude
-// CHECK:STDOUT:     import Core//prelude/...
-// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .Derived = %Derived.decl
 // CHECK:STDOUT:     .Base = %Base.decl
@@ -592,79 +406,17 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:   %Derived.decl: type = class_decl @Derived [concrete = constants.%Derived] {} {}
 // CHECK:STDOUT:   %Base.decl: type = class_decl @Base [concrete = constants.%Base] {} {}
 // CHECK:STDOUT:   %Base.f.decl: %Base.f.type = fn_decl @Base.f [concrete = constants.%Base.f] {
-// CHECK:STDOUT:     %self.patt: %pattern_type.a3a = binding_pattern self [concrete]
-// CHECK:STDOUT:     %self.param_patt: %pattern_type.a3a = value_param_pattern %self.patt, call_param0 [concrete]
+// CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %self.param: %Base = value_param call_param0
-// CHECK:STDOUT:     %self: %Base = bind_name self, %self.param
+// CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Base.g.decl: %Base.g.type = fn_decl @Base.g [concrete = constants.%Base.g] {
-// CHECK:STDOUT:     %self.patt: %pattern_type.a3a = binding_pattern self [concrete]
-// CHECK:STDOUT:     %self.param_patt: %pattern_type.a3a = value_param_pattern %self.patt, call_param0 [concrete]
+// CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %self.param: %Base = value_param call_param0
-// CHECK:STDOUT:     %self: %Base = bind_name self, %self.param
+// CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: file {
-// CHECK:STDOUT:   package: <namespace> = namespace [concrete] {
-// CHECK:STDOUT:     .Core = imports.%Core
-// CHECK:STDOUT:     .Cpp = imports.%Cpp
-// CHECK:STDOUT:     .CallDirect = %CallDirect.decl
-// CHECK:STDOUT:     .CallQualified = %CallQualified.decl
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import = import Core
-// CHECK:STDOUT:   %Cpp.import_cpp = import_cpp {
-// CHECK:STDOUT:     import Cpp "base_method.h"
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %CallDirect.decl: %CallDirect.type = fn_decl @CallDirect [concrete = constants.%CallDirect] {
-// CHECK:STDOUT:     %d.patt: %pattern_type.5de = binding_pattern d [concrete]
-// CHECK:STDOUT:     %d.param_patt: %pattern_type.5de = value_param_pattern %d.patt, call_param0 [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %d.param: %Derived = value_param call_param0
-// CHECK:STDOUT:     %.loc6: type = splice_block %Derived.ref [concrete = constants.%Derived] {
-// CHECK:STDOUT:       %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:       %Derived.ref: type = name_ref Derived, imports.%Derived.decl [concrete = constants.%Derived]
-// CHECK:STDOUT:     }
-// CHECK:STDOUT:     %d: %Derived = bind_name d, %d.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %CallQualified.decl: %CallQualified.type = fn_decl @CallQualified [concrete = constants.%CallQualified] {
-// CHECK:STDOUT:     %d.patt: %pattern_type.5de = binding_pattern d [concrete]
-// CHECK:STDOUT:     %d.param_patt: %pattern_type.5de = value_param_pattern %d.patt, call_param0 [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %d.param: %Derived = value_param call_param0
-// CHECK:STDOUT:     %.loc12: type = splice_block %Derived.ref [concrete = constants.%Derived] {
-// CHECK:STDOUT:       %Cpp.ref.loc12: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:       %Derived.ref: type = name_ref Derived, imports.%Derived.decl [concrete = constants.%Derived]
-// CHECK:STDOUT:     }
-// CHECK:STDOUT:     %d: %Derived = bind_name d, %d.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @Derived {
-// CHECK:STDOUT:   %.1: %Derived.elem = base_decl imports.%Base.decl, element0 [concrete]
-// CHECK:STDOUT:   %.2: type = custom_layout_type {size=1, align=1, .base@0: %Base} [concrete = constants.%.52d]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %.2 [concrete = constants.%complete_type.fd1]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%Derived
-// CHECK:STDOUT:   .f = imports.%Base.f.decl
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @Base {
-// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete = constants.%empty_struct_type]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %empty_struct_type [concrete = constants.%complete_type.357]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%Base
-// CHECK:STDOUT:   .g = imports.%Base.g.decl
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
 // CHECK:STDOUT: fn @CallDirect(%d.param: %Derived) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %d.ref: %Derived = name_ref d, %d
@@ -674,11 +426,9 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:   %.loc8_3.2: ref %Base = converted %d.ref, %.loc8_3.1
 // CHECK:STDOUT:   %.loc8_3.3: %Base = bind_value %.loc8_3.2
 // CHECK:STDOUT:   %Base.f.call: init %empty_tuple.type = call %Base.f.bound(%.loc8_3.3)
-// CHECK:STDOUT:   return
+// CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: fn @Base.f(%self.param: %Base);
-// CHECK:STDOUT:
 // CHECK:STDOUT: fn @CallQualified(%d.param: %Derived) {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %d.ref: %Derived = name_ref d, %d
@@ -690,265 +440,6 @@ fn Convert(p: Cpp.B*) -> Cpp.A* {
 // CHECK:STDOUT:   %.loc14_3.2: ref %Base = converted %d.ref, %.loc14_3.1
 // CHECK:STDOUT:   %.loc14_3.3: %Base = bind_value %.loc14_3.2
 // CHECK:STDOUT:   %Base.g.call: init %empty_tuple.type = call %Base.g.bound(%.loc14_3.3)
-// CHECK:STDOUT:   return
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @Base.g(%self.param: %Base);
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_use_multiple_inheritance.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %C: type = class_type @C [concrete]
-// CHECK:STDOUT:   %A: type = class_type @A [concrete]
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
-// CHECK:STDOUT:   %Int.type: type = generic_class_type @Int [concrete]
-// CHECK:STDOUT:   %Int.generic: %Int.type = struct_value () [concrete]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
-// CHECK:STDOUT:   %A.elem: type = unbound_element_type %A, %i32 [concrete]
-// CHECK:STDOUT:   %.79a: type = custom_layout_type {size=4, align=4, .a@0: %i32} [concrete]
-// CHECK:STDOUT:   %complete_type.33a: <witness> = complete_type_witness %.79a [concrete]
-// CHECK:STDOUT:   %C.elem.1e5: type = unbound_element_type %C, %A [concrete]
-// CHECK:STDOUT:   %B: type = class_type @B [concrete]
-// CHECK:STDOUT:   %B.elem: type = unbound_element_type %B, %i32 [concrete]
-// CHECK:STDOUT:   %.903: type = custom_layout_type {size=4, align=4, .b@0: %i32} [concrete]
-// CHECK:STDOUT:   %complete_type.fb9: <witness> = complete_type_witness %.903 [concrete]
-// CHECK:STDOUT:   %C.elem.874: type = unbound_element_type %C, %B [concrete]
-// CHECK:STDOUT:   %.dba: type = custom_layout_type {size=8, align=4, .base@0: %A, .base@4: %B} [concrete]
-// CHECK:STDOUT:   %complete_type.1ad: <witness> = complete_type_witness %.dba [concrete]
-// CHECK:STDOUT:   %ptr.d9e: type = ptr_type %C [concrete]
-// CHECK:STDOUT:   %pattern_type.a31: type = pattern_type %ptr.d9e [concrete]
-// CHECK:STDOUT:   %ptr.270: type = ptr_type %A [concrete]
-// CHECK:STDOUT:   %pattern_type.bcf: type = pattern_type %ptr.270 [concrete]
-// CHECK:STDOUT:   %ConvertA.type: type = fn_type @ConvertA [concrete]
-// CHECK:STDOUT:   %ConvertA: %ConvertA.type = struct_value () [concrete]
-// CHECK:STDOUT:   %ImplicitAs.type.cc7: type = generic_interface_type @ImplicitAs [concrete]
-// CHECK:STDOUT:   %ImplicitAs.generic: %ImplicitAs.type.cc7 = struct_value () [concrete]
-// CHECK:STDOUT:   %ptr.a04: type = ptr_type %B [concrete]
-// CHECK:STDOUT:   %pattern_type.837: type = pattern_type %ptr.a04 [concrete]
-// CHECK:STDOUT:   %ConvertB.type: type = fn_type @ConvertB [concrete]
-// CHECK:STDOUT:   %ConvertB: %ConvertB.type = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [concrete] {
-// CHECK:STDOUT:     .Int = %Core.Int
-// CHECK:STDOUT:     .ImplicitAs = %Core.ImplicitAs
-// CHECK:STDOUT:     import Core//prelude
-// CHECK:STDOUT:     import Core//prelude/...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .C = %C.decl
-// CHECK:STDOUT:     .A = %A.decl
-// CHECK:STDOUT:     .B = %B.decl
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %C.decl: type = class_decl @C [concrete = constants.%C] {} {}
-// CHECK:STDOUT:   %A.decl: type = class_decl @A [concrete = constants.%A] {} {}
-// CHECK:STDOUT:   %Core.Int: %Int.type = import_ref Core//prelude/parts/int, Int, loaded [concrete = constants.%Int.generic]
-// CHECK:STDOUT:   %B.decl: type = class_decl @B [concrete = constants.%B] {} {}
-// CHECK:STDOUT:   %Core.ImplicitAs: %ImplicitAs.type.cc7 = import_ref Core//prelude/parts/as, ImplicitAs, loaded [concrete = constants.%ImplicitAs.generic]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: file {
-// CHECK:STDOUT:   package: <namespace> = namespace [concrete] {
-// CHECK:STDOUT:     .Core = imports.%Core
-// CHECK:STDOUT:     .Cpp = imports.%Cpp
-// CHECK:STDOUT:     .ConvertA = %ConvertA.decl
-// CHECK:STDOUT:     .ConvertB = %ConvertB.decl
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import = import Core
-// CHECK:STDOUT:   %Cpp.import_cpp = import_cpp {
-// CHECK:STDOUT:     import Cpp "multiple_inheritance.h"
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %ConvertA.decl: %ConvertA.type = fn_decl @ConvertA [concrete = constants.%ConvertA] {
-// CHECK:STDOUT:     %p.patt: %pattern_type.a31 = binding_pattern p [concrete]
-// CHECK:STDOUT:     %p.param_patt: %pattern_type.a31 = value_param_pattern %p.patt, call_param0 [concrete]
-// CHECK:STDOUT:     %return.patt: %pattern_type.bcf = return_slot_pattern [concrete]
-// CHECK:STDOUT:     %return.param_patt: %pattern_type.bcf = out_param_pattern %return.patt, call_param1 [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %Cpp.ref.loc6_27: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:     %A.ref: type = name_ref A, imports.%A.decl [concrete = constants.%A]
-// CHECK:STDOUT:     %ptr.loc6_32: type = ptr_type %A.ref [concrete = constants.%ptr.270]
-// CHECK:STDOUT:     %p.param: %ptr.d9e = value_param call_param0
-// CHECK:STDOUT:     %.loc6: type = splice_block %ptr.loc6_21 [concrete = constants.%ptr.d9e] {
-// CHECK:STDOUT:       %Cpp.ref.loc6_16: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:       %C.ref: type = name_ref C, imports.%C.decl [concrete = constants.%C]
-// CHECK:STDOUT:       %ptr.loc6_21: type = ptr_type %C.ref [concrete = constants.%ptr.d9e]
-// CHECK:STDOUT:     }
-// CHECK:STDOUT:     %p: %ptr.d9e = bind_name p, %p.param
-// CHECK:STDOUT:     %return.param: ref %ptr.270 = out_param call_param1
-// CHECK:STDOUT:     %return: ref %ptr.270 = return_slot %return.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %ConvertB.decl: %ConvertB.type = fn_decl @ConvertB [concrete = constants.%ConvertB] {
-// CHECK:STDOUT:     %p.patt: %pattern_type.a31 = binding_pattern p [concrete]
-// CHECK:STDOUT:     %p.param_patt: %pattern_type.a31 = value_param_pattern %p.patt, call_param0 [concrete]
-// CHECK:STDOUT:     %return.patt: %pattern_type.837 = return_slot_pattern [concrete]
-// CHECK:STDOUT:     %return.param_patt: %pattern_type.837 = out_param_pattern %return.patt, call_param1 [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %Cpp.ref.loc17_27: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:     %B.ref: type = name_ref B, imports.%B.decl [concrete = constants.%B]
-// CHECK:STDOUT:     %ptr.loc17_32: type = ptr_type %B.ref [concrete = constants.%ptr.a04]
-// CHECK:STDOUT:     %p.param: %ptr.d9e = value_param call_param0
-// CHECK:STDOUT:     %.loc17: type = splice_block %ptr.loc17_21 [concrete = constants.%ptr.d9e] {
-// CHECK:STDOUT:       %Cpp.ref.loc17_16: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:       %C.ref: type = name_ref C, imports.%C.decl [concrete = constants.%C]
-// CHECK:STDOUT:       %ptr.loc17_21: type = ptr_type %C.ref [concrete = constants.%ptr.d9e]
-// CHECK:STDOUT:     }
-// CHECK:STDOUT:     %p: %ptr.d9e = bind_name p, %p.param
-// CHECK:STDOUT:     %return.param: ref %ptr.a04 = out_param call_param1
-// CHECK:STDOUT:     %return: ref %ptr.a04 = return_slot %return.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @C {
-// CHECK:STDOUT:   %.1: %C.elem.1e5 = base_decl imports.%A.decl, element0 [concrete]
-// CHECK:STDOUT:   %.2: %C.elem.874 = base_decl imports.%B.decl, element1 [concrete]
-// CHECK:STDOUT:   %.3: type = custom_layout_type {size=8, align=4, .base@0: %A, .base@4: %B} [concrete = constants.%.dba]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %.3 [concrete = constants.%complete_type.1ad]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%C
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @A {
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:   %.1: %A.elem = field_decl a, element0 [concrete]
-// CHECK:STDOUT:   %.2: type = custom_layout_type {size=4, align=4, .a@0: %i32} [concrete = constants.%.79a]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %.2 [concrete = constants.%complete_type.33a]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%A
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @B {
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:   %.1: %B.elem = field_decl b, element0 [concrete]
-// CHECK:STDOUT:   %.2: type = custom_layout_type {size=4, align=4, .b@0: %i32} [concrete = constants.%.903]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %.2 [concrete = constants.%complete_type.fb9]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%B
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @ConvertA(%p.param: %ptr.d9e) -> %ptr.270 {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %p.ref: %ptr.d9e = name_ref p, %p
-// CHECK:STDOUT:   %.loc14: %ptr.270 = converted %p.ref, <error> [concrete = <error>]
-// CHECK:STDOUT:   return <error>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @ConvertB(%p.param: %ptr.d9e) -> %ptr.a04 {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %p.ref: %ptr.d9e = name_ref p, %p
-// CHECK:STDOUT:   %.loc25: %ptr.a04 = converted %p.ref, <error> [concrete = <error>]
-// CHECK:STDOUT:   return <error>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_use_virtual_inheritance.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %B: type = class_type @B [concrete]
-// CHECK:STDOUT:   %ptr.a04: type = ptr_type %B [concrete]
-// CHECK:STDOUT:   %pattern_type.837: type = pattern_type %ptr.a04 [concrete]
-// CHECK:STDOUT:   %A: type = class_type @A [concrete]
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
-// CHECK:STDOUT:   %Int.type: type = generic_class_type @Int [concrete]
-// CHECK:STDOUT:   %Int.generic: %Int.type = struct_value () [concrete]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
-// CHECK:STDOUT:   %A.elem: type = unbound_element_type %A, %i32 [concrete]
-// CHECK:STDOUT:   %.79a: type = custom_layout_type {size=4, align=4, .a@0: %i32} [concrete]
-// CHECK:STDOUT:   %complete_type.33a: <witness> = complete_type_witness %.79a [concrete]
-// CHECK:STDOUT:   %ptr.270: type = ptr_type %A [concrete]
-// CHECK:STDOUT:   %pattern_type.bcf: type = pattern_type %ptr.270 [concrete]
-// CHECK:STDOUT:   %Convert.type: type = fn_type @Convert [concrete]
-// CHECK:STDOUT:   %Convert: %Convert.type = struct_value () [concrete]
-// CHECK:STDOUT:   %ImplicitAs.type.cc7: type = generic_interface_type @ImplicitAs [concrete]
-// CHECK:STDOUT:   %ImplicitAs.generic: %ImplicitAs.type.cc7 = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Core: <namespace> = namespace file.%Core.import, [concrete] {
-// CHECK:STDOUT:     .Int = %Core.Int
-// CHECK:STDOUT:     .ImplicitAs = %Core.ImplicitAs
-// CHECK:STDOUT:     import Core//prelude
-// CHECK:STDOUT:     import Core//prelude/...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .B = %B.decl
-// CHECK:STDOUT:     .A = %A.decl
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %B.decl: type = class_decl @B [concrete = constants.%B] {} {}
-// CHECK:STDOUT:   %A.decl: type = class_decl @A [concrete = constants.%A] {} {}
-// CHECK:STDOUT:   %Core.Int: %Int.type = import_ref Core//prelude/parts/int, Int, loaded [concrete = constants.%Int.generic]
-// CHECK:STDOUT:   %Core.ImplicitAs: %ImplicitAs.type.cc7 = import_ref Core//prelude/parts/as, ImplicitAs, loaded [concrete = constants.%ImplicitAs.generic]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: file {
-// CHECK:STDOUT:   package: <namespace> = namespace [concrete] {
-// CHECK:STDOUT:     .Core = imports.%Core
-// CHECK:STDOUT:     .Cpp = imports.%Cpp
-// CHECK:STDOUT:     .Convert = %Convert.decl
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import = import Core
-// CHECK:STDOUT:   %Cpp.import_cpp = import_cpp {
-// CHECK:STDOUT:     import Cpp "virtual_inheritance.h"
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Convert.decl: %Convert.type = fn_decl @Convert [concrete = constants.%Convert] {
-// CHECK:STDOUT:     %p.patt: %pattern_type.837 = binding_pattern p [concrete]
-// CHECK:STDOUT:     %p.param_patt: %pattern_type.837 = value_param_pattern %p.patt, call_param0 [concrete]
-// CHECK:STDOUT:     %return.patt: %pattern_type.bcf = return_slot_pattern [concrete]
-// CHECK:STDOUT:     %return.param_patt: %pattern_type.bcf = out_param_pattern %return.patt, call_param1 [concrete]
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     %Cpp.ref.loc12_26: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:     %A.ref: type = name_ref A, imports.%A.decl [concrete = constants.%A]
-// CHECK:STDOUT:     %ptr.loc12_31: type = ptr_type %A.ref [concrete = constants.%ptr.270]
-// CHECK:STDOUT:     %p.param: %ptr.a04 = value_param call_param0
-// CHECK:STDOUT:     %.loc12: type = splice_block %ptr.loc12_20 [concrete = constants.%ptr.a04] {
-// CHECK:STDOUT:       %Cpp.ref.loc12_15: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:       %B.ref: type = name_ref B, imports.%B.decl [concrete = constants.%B]
-// CHECK:STDOUT:       %ptr.loc12_20: type = ptr_type %B.ref [concrete = constants.%ptr.a04]
-// CHECK:STDOUT:     }
-// CHECK:STDOUT:     %p: %ptr.a04 = bind_name p, %p.param
-// CHECK:STDOUT:     %return.param: ref %ptr.270 = out_param call_param1
-// CHECK:STDOUT:     %return: ref %ptr.270 = return_slot %return.param
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @B {
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness <error> [concrete = <error>]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%B
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: class @A {
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete = constants.%int_32]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(constants.%int_32) [concrete = constants.%i32]
-// CHECK:STDOUT:   %.1: %A.elem = field_decl a, element0 [concrete]
-// CHECK:STDOUT:   %.2: type = custom_layout_type {size=4, align=4, .a@0: %i32} [concrete = constants.%.79a]
-// CHECK:STDOUT:   %complete_type: <witness> = complete_type_witness %.2 [concrete = constants.%complete_type.33a]
-// CHECK:STDOUT:   complete_type_witness = %complete_type
-// CHECK:STDOUT:
-// CHECK:STDOUT: !members:
-// CHECK:STDOUT:   .Self = constants.%A
-// CHECK:STDOUT:   import Cpp//...
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @Convert(%p.param: %ptr.a04) -> %ptr.270 {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %p.ref: %ptr.a04 = name_ref p, %p
-// CHECK:STDOUT:   %.loc20: %ptr.270 = converted %p.ref, <error> [concrete = <error>]
-// CHECK:STDOUT:   return <error>
+// CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/check/testdata/interop/cpp/class/union.carbon b/toolchain/check/testdata/interop/cpp/class/union.carbon
index d872822cc803..c40a036451ce 100644
--- a/toolchain/check/testdata/interop/cpp/class/union.carbon
+++ b/toolchain/check/testdata/interop/cpp/class/union.carbon
@@ -161,32 +161,6 @@ fn MyF(bar : Cpp.Bar*) {
 }
 //@dump-sem-ir-end
 
-// ============================================================================
-// To inherit public
-// ============================================================================
-
-// --- to_inherit_public.h
-
-union Bar {
- public:
-  static auto foo() -> void;
-};
-
-// --- todo_fail_import_to_inherit_public.carbon
-
-library "[[@TEST_NAME]]";
-
-import Cpp library "to_inherit_public.h";
-
-class Derived {
-  // TODO: Presumably we should disallow deriving from a union.
-  extend base: Cpp.Bar;
-}
-
-fn MyF() {
-  Derived.foo();
-}
-
 // ============================================================================
 // Template
 // ============================================================================