diff --git a/toolchain/check/import_cpp.cpp b/toolchain/check/import_cpp.cpp
index 2d567ec6bd75..fcbf942429eb 100644
--- a/toolchain/check/import_cpp.cpp
+++ b/toolchain/check/import_cpp.cpp
@@ -618,6 +618,12 @@ static auto ImportCXXRecordDecl(Context& context, SemIR::LocId loc_id,
     return SemIR::ErrorInst::InstId;
   }
 
+  if (clang_def->isUnion() && !clang_def->fields().empty()) {
+    context.TODO(loc_id, "Unsupported: Non-empty union");
+    MarkFailedDecl(context, clang_decl);
+    return SemIR::ErrorInst::InstId;
+  }
+
   auto [class_id, class_def_id] =
       BuildClassDefinition(context, parent_scope_id, name_id, clang_def);
 
@@ -662,8 +668,7 @@ static auto MapBuiltinType(Context& context, const clang::BuiltinType& type)
     default:
       break;
   }
-  return {.inst_id = SemIR::ErrorInst::TypeInstId,
-          .type_id = SemIR::ErrorInst::TypeId};
+  return {.inst_id = SemIR::TypeInstId::None, .type_id = SemIR::TypeId::None};
 }
 
 // Maps a C++ record type to a Carbon type.
@@ -671,52 +676,52 @@ static auto MapBuiltinType(Context& context, const clang::BuiltinType& type)
 static auto MapRecordType(Context& context, SemIR::LocId loc_id,
                           const clang::RecordType& type) -> TypeExpr {
   auto* record_decl = clang::dyn_cast<clang::CXXRecordDecl>(type.getDecl());
-  if (record_decl && !record_decl->isUnion()) {
-    auto& clang_decls = context.sem_ir().clang_decls();
-    SemIR::InstId record_inst_id = SemIR::InstId::None;
-    if (auto record_clang_decl_id = clang_decls.Lookup(record_decl);
-        record_clang_decl_id.has_value()) {
-      record_inst_id = clang_decls.Get(record_clang_decl_id).inst_id;
-    } else {
-      auto parent_inst_id =
-          AsCarbonNamespace(context, record_decl->getDeclContext());
-      auto parent_name_scope_id =
-          context.insts().GetAs<SemIR::Namespace>(parent_inst_id).name_scope_id;
-      SemIR::NameId record_name_id =
-          AddIdentifierName(context, record_decl->getName());
-      record_inst_id = ImportCXXRecordDecl(
-          context, loc_id, parent_name_scope_id, record_name_id, record_decl);
-      AddNameToScope(context, parent_name_scope_id, record_name_id,
-                     record_inst_id);
-    }
-    SemIR::TypeInstId record_type_inst_id =
-        context.types().GetAsTypeInstId(record_inst_id);
-    return {
-        .inst_id = record_type_inst_id,
-        .type_id = context.types().GetTypeIdForTypeInstId(record_type_inst_id)};
+  if (!record_decl) {
+    return {.inst_id = SemIR::TypeInstId::None, .type_id = SemIR::TypeId::None};
   }
 
-  return {.inst_id = SemIR::ErrorInst::TypeInstId,
-          .type_id = SemIR::ErrorInst::TypeId};
+  auto& clang_decls = context.sem_ir().clang_decls();
+  SemIR::InstId record_inst_id = SemIR::InstId::None;
+  if (auto record_clang_decl_id = clang_decls.Lookup(record_decl);
+      record_clang_decl_id.has_value()) {
+    record_inst_id = clang_decls.Get(record_clang_decl_id).inst_id;
+  } else {
+    auto parent_inst_id =
+        AsCarbonNamespace(context, record_decl->getDeclContext());
+    auto parent_name_scope_id =
+        context.insts().GetAs<SemIR::Namespace>(parent_inst_id).name_scope_id;
+    SemIR::NameId record_name_id =
+        AddIdentifierName(context, record_decl->getName());
+    record_inst_id = ImportCXXRecordDecl(context, loc_id, parent_name_scope_id,
+                                         record_name_id, record_decl);
+  }
+  SemIR::TypeInstId record_type_inst_id =
+      context.types().GetAsTypeInstId(record_inst_id);
+  return {
+      .inst_id = record_type_inst_id,
+      .type_id = context.types().GetTypeIdForTypeInstId(record_type_inst_id)};
 }
 
 // Maps a C++ non-pointer type to a Carbon type.
 // TODO: Support more types.
 static auto MapNonPointerType(Context& context, SemIR::LocId loc_id,
                               clang::QualType type) -> TypeExpr {
-  type = type.getCanonicalType();
+  if (type.hasQualifiers()) {
+    // TODO: Support type qualifiers.
+    return {.inst_id = SemIR::TypeInstId::None, .type_id = SemIR::TypeId::None};
+  }
+
   CARBON_CHECK(!type->isPointerType());
 
-  if (const auto* builtin_type = dyn_cast<clang::BuiltinType>(type)) {
+  if (const auto* builtin_type = type->getAs<clang::BuiltinType>()) {
     return MapBuiltinType(context, *builtin_type);
   }
 
-  if (const auto* record_type = clang::dyn_cast<clang::RecordType>(type)) {
+  if (const auto* record_type = type->getAs<clang::RecordType>()) {
     return MapRecordType(context, loc_id, *record_type);
   }
 
-  return {.inst_id = SemIR::ErrorInst::TypeInstId,
-          .type_id = SemIR::ErrorInst::TypeId};
+  return {.inst_id = SemIR::TypeInstId::None, .type_id = SemIR::TypeId::None};
 }
 
 // Maps a C++ pointer type to a Carbon pointer type.
@@ -744,10 +749,8 @@ static auto MapPointerType(Context& context, SemIR::LocId loc_id,
   }
 
   TypeExpr pointee_type_expr = MapNonPointerType(context, loc_id, pointee_type);
-  if (pointee_type_expr.inst_id == SemIR::ErrorInst::InstId ||
-      pointee_type_expr.type_id == SemIR::ErrorInst::TypeId) {
-    return {.inst_id = SemIR::ErrorInst::TypeInstId,
-            .type_id = SemIR::ErrorInst::TypeId};
+  if (!pointee_type_expr.inst_id.has_value()) {
+    return {.inst_id = SemIR::TypeInstId::None, .type_id = SemIR::TypeId::None};
   }
 
   SemIR::TypeId pointer_type_id =
@@ -770,7 +773,7 @@ static auto MapType(Context& context, SemIR::LocId loc_id, clang::QualType type)
 // Returns a block id for the explicit parameters of the given function
 // declaration. If the function declaration has no parameters, it returns
 // `SemIR::InstBlockId::Empty`. In the case of an unsupported parameter type, it
-// returns `SemIR::InstBlockId::None`.
+// produces an error and returns `SemIR::InstBlockId::None`.
 // TODO: Consider refactoring to extract and reuse more logic from
 // `HandleAnyBindingPattern()`.
 static auto MakeParamPatternsBlockId(Context& context, SemIR::LocId loc_id,
@@ -794,7 +797,7 @@ static auto MakeParamPatternsBlockId(Context& context, SemIR::LocId loc_id,
     SemIR::ExprRegionId type_expr_region_id =
         EndSubpatternAsExpr(context, type_inst_id);
 
-    if (type_id == SemIR::ErrorInst::TypeId) {
+    if (!type_id.has_value()) {
       context.TODO(loc_id, llvm::formatv("Unsupported: parameter type: {0}",
                                          param_type.getAsString()));
       return SemIR::InstBlockId::None;
@@ -830,7 +833,8 @@ static auto MakeParamPatternsBlockId(Context& context, SemIR::LocId loc_id,
 }
 
 // Returns the return type of the given function declaration. In case of an
-// unsupported return type, it returns `SemIR::ErrorInst::InstId`.
+// unsupported return type, it produces a diagnostic and returns
+// `SemIR::ErrorInst::InstId`.
 // TODO: Support more return types.
 static auto GetReturnType(Context& context, SemIR::LocId loc_id,
                           const clang::FunctionDecl* clang_decl)
@@ -841,7 +845,7 @@ static auto GetReturnType(Context& context, SemIR::LocId loc_id,
   }
 
   auto [type_inst_id, type_id] = MapType(context, loc_id, ret_type);
-  if (type_id == SemIR::ErrorInst::TypeId) {
+  if (!type_inst_id.has_value()) {
     context.TODO(loc_id, llvm::formatv("Unsupported: return type: {0}",
                                        ret_type.getAsString()));
     return SemIR::ErrorInst::InstId;
@@ -878,8 +882,8 @@ struct FunctionParamsInsts {
 // to create the Call parameters instructions block. Currently the implicit
 // parameter patterns are not taken into account. Returns the parameter patterns
 // block id, the return slot pattern id, and the call parameters block id.
-// Returns `std::nullopt` if the function declaration has an unsupported
-// parameter type.
+// Produces a diagnostic and returns `std::nullopt` if the function declaration
+// has an unsupported parameter type.
 static auto CreateFunctionParamsInsts(Context& context, SemIR::LocId loc_id,
                                       const clang::FunctionDecl* clang_decl)
     -> std::optional<FunctionParamsInsts> {
@@ -992,10 +996,15 @@ static auto ImportNameDecl(Context& context, SemIR::LocId loc_id,
     return ImportNamespaceDecl(context, scope_id, name_id,
                                clang_namespace_decl);
   }
-  if (auto* clang_record_decl =
-          clang::dyn_cast<clang::CXXRecordDecl>(clang_decl)) {
-    return ImportCXXRecordDecl(context, loc_id, scope_id, name_id,
-                               clang_record_decl);
+  if (auto* type_decl = clang::dyn_cast<clang::TypeDecl>(clang_decl)) {
+    auto type = type_decl->getASTContext().getTypeDeclType(type_decl);
+    auto type_inst_id = MapType(context, loc_id, type).inst_id;
+    if (!type_inst_id.has_value()) {
+      context.TODO(loc_id, llvm::formatv("Unsupported: Type declaration: {0}",
+                                         type.getAsString()));
+      return SemIR::ErrorInst::InstId;
+    }
+    return type_inst_id;
   }
 
   context.TODO(loc_id, llvm::formatv("Unsupported: Declaration type {0}",
diff --git a/toolchain/check/testdata/interop/cpp/function/class.carbon b/toolchain/check/testdata/interop/cpp/function/class.carbon
index bb219c128b91..c113ecf15065 100644
--- a/toolchain/check/testdata/interop/cpp/function/class.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/class.carbon
@@ -27,14 +27,7 @@ library "[[@TEST_NAME]]";
 import Cpp library "decl_value_param_type.h";
 
 fn F() {
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: C` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo({});
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -63,13 +56,6 @@ fn F() {
   // CHECK:STDERR:               ^
   // CHECK:STDERR:
   let c: Cpp.C;
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type_previously_imported.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: C` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(c);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type_previously_imported.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo(c);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo(c);
 }
 
@@ -91,14 +77,7 @@ library "[[@TEST_NAME]]";
 import Cpp library "double_decl_value_param_type.h";
 
 fn F() {
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo1({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo1` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo1({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: C` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo1({});
   // CHECK:STDERR:   ^~~~~~~~
   // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo1` [InCppNameLookup]
@@ -106,13 +85,6 @@ fn F() {
   // CHECK:STDERR:   ^~~~~~~~
   // CHECK:STDERR:
   Cpp.foo1({});
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: C` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo2({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo2` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo2({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR:
   Cpp.foo2({});
 }
 
@@ -300,13 +272,6 @@ import Cpp library "decl_pointer_param_type.h";
 // CHECK:STDERR:
 fn F(c: Cpp.C*) {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_decl_pointer_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: C * _Nonnull` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(c);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_pointer_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo(c);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo(c);
   //@dump-sem-ir-end
 }
@@ -350,14 +315,7 @@ library "[[@TEST_NAME]]";
 import Cpp library "decl_value_return_type.h";
 
 fn F() {
-  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: return type: C` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo();
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -407,14 +365,7 @@ import Cpp library "decl_pointer_return_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: return type: C * _Nonnull` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo();
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -473,10 +424,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .C = %C.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %C.decl: type = class_decl @C [concrete = constants.%C] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -532,10 +481,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .C = %C.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %C.decl: type = class_decl @C [concrete = constants.%C] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -591,10 +538,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .C = %C.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %C.decl: type = class_decl @C [concrete = constants.%C] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -879,21 +824,30 @@ fn F() {
 // CHECK:STDOUT: --- fail_todo_import_decl_pointer_param_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .C = <error>
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F(%c.param: <error>) {
 // CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %Cpp.ref.loc22: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %Cpp.ref.loc15: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %c.ref: <error> = name_ref c, %c
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -954,10 +908,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .C = %C.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %C.decl: type = class_decl @C [concrete = constants.%C] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -986,20 +938,27 @@ fn F() {
 // CHECK:STDOUT: --- fail_todo_import_decl_pointer_return_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
-// CHECK:STDOUT:     .C = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %foo.call: init <error> = call %foo.ref()
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1015,10 +974,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .C = %C.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %C.decl: type = class_decl @C [concrete = constants.%C] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
diff --git a/toolchain/check/testdata/interop/cpp/function/param_int16.carbon b/toolchain/check/testdata/interop/cpp/function/param_int16.carbon
index 89faf69d88eb..d1a04f05f108 100644
--- a/toolchain/check/testdata/interop/cpp/function/param_int16.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/param_int16.carbon
@@ -195,7 +195,7 @@ fn F() {
 
 auto foo(const short a) -> void;
 
-// --- import_const_short.carbon
+// --- fail_todo_import_const_short.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -203,6 +203,13 @@ import Cpp library "const_short.h";
 
 fn F() {
   //@dump-sem-ir-begin
+  // CHECK:STDERR: fail_todo_import_const_short.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: const short` [SemanticsTodo]
+  // CHECK:STDERR:   Cpp.foo(1 as i16);
+  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR: fail_todo_import_const_short.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
+  // CHECK:STDERR:   Cpp.foo(1 as i16);
+  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR:
   Cpp.foo(1 as i16);
   //@dump-sem-ir-end
 }
@@ -292,7 +299,7 @@ fn F() {
 
 auto foo(const short* _Nonnull a) -> void;
 
-// --- import_const_short_pointer.carbon
+// --- fail_todo_import_const_short_pointer.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -301,6 +308,13 @@ import Cpp library "const_short_pointer.h";
 fn F() {
   var a: i16 = 1;
   //@dump-sem-ir-begin
+  // CHECK:STDERR: fail_todo_import_const_short_pointer.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: const short * _Nonnull` [SemanticsTodo]
+  // CHECK:STDERR:   Cpp.foo(&a);
+  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR: fail_todo_import_const_short_pointer.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
+  // CHECK:STDERR:   Cpp.foo(&a);
+  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR:
   Cpp.foo(&a);
   //@dump-sem-ir-end
 }
@@ -717,15 +731,12 @@ fn F() {
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- import_const_short.carbon
+// CHECK:STDOUT: --- fail_todo_import_const_short.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %int_1.5b8: Core.IntLiteral = int_value 1 [concrete]
 // CHECK:STDOUT:   %int_16: Core.IntLiteral = int_value 16 [concrete]
 // CHECK:STDOUT:   %i16: type = class_type @Int, @Int(%int_16) [concrete]
-// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
-// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
-// CHECK:STDOUT:   %int_1.5b8: Core.IntLiteral = int_value 1 [concrete]
 // CHECK:STDOUT:   %As.type.a96: type = facet_type <@As, @As(%i16)> [concrete]
 // CHECK:STDOUT:   %Convert.type.be5: type = fn_type @Convert.1, @As(%i16) [concrete]
 // CHECK:STDOUT:   %To: Core.IntLiteral = bind_symbolic_name To, 0 [symbolic]
@@ -744,14 +755,9 @@ fn F() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %foo.decl
+// CHECK:STDOUT:     .foo = <error>
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Core.import_ref.78a: @impl.686.%Convert.type (%Convert.type.062) = import_ref Core//prelude/parts/int, loc25_39, loaded [symbolic = @impl.686.%Convert (constants.%Convert.527)]
 // CHECK:STDOUT:   %As.impl_witness_table.eb4 = impl_witness_table (%Core.import_ref.78a), @impl.686 [concrete]
 // CHECK:STDOUT: }
@@ -759,18 +765,17 @@ fn F() {
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
 // CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1.5b8]
 // CHECK:STDOUT:   %int_16: Core.IntLiteral = int_value 16 [concrete = constants.%int_16]
 // CHECK:STDOUT:   %i16: type = class_type @Int, @Int(constants.%int_16) [concrete = constants.%i16]
 // CHECK:STDOUT:   %impl.elem0: %.91d = impl_witness_access constants.%As.impl_witness.0ef, element0 [concrete = constants.%Convert.489]
-// CHECK:STDOUT:   %bound_method.loc8_13.1: <bound method> = bound_method %int_1, %impl.elem0 [concrete = constants.%Convert.bound]
+// CHECK:STDOUT:   %bound_method.loc15_13.1: <bound method> = bound_method %int_1, %impl.elem0 [concrete = constants.%Convert.bound]
 // CHECK:STDOUT:   %specific_fn: <specific function> = specific_function %impl.elem0, @Convert.5(constants.%int_16) [concrete = constants.%Convert.specific_fn]
-// CHECK:STDOUT:   %bound_method.loc8_13.2: <bound method> = bound_method %int_1, %specific_fn [concrete = constants.%bound_method]
-// CHECK:STDOUT:   %int.convert_checked: init %i16 = call %bound_method.loc8_13.2(%int_1) [concrete = constants.%int_1.f90]
-// CHECK:STDOUT:   %.loc8_13.1: %i16 = value_of_initializer %int.convert_checked [concrete = constants.%int_1.f90]
-// CHECK:STDOUT:   %.loc8_13.2: %i16 = converted %int_1, %.loc8_13.1 [concrete = constants.%int_1.f90]
-// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%.loc8_13.2)
+// CHECK:STDOUT:   %bound_method.loc15_13.2: <bound method> = bound_method %int_1, %specific_fn [concrete = constants.%bound_method]
+// CHECK:STDOUT:   %int.convert_checked: init %i16 = call %bound_method.loc15_13.2(%int_1) [concrete = constants.%int_1.f90]
+// CHECK:STDOUT:   %.loc15_13.1: %i16 = value_of_initializer %int.convert_checked [concrete = constants.%int_1.f90]
+// CHECK:STDOUT:   %.loc15_13.2: %i16 = converted %int_1, %.loc15_13.1 [concrete = constants.%int_1.f90]
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -854,37 +859,28 @@ fn F() {
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- import_const_short_pointer.carbon
+// CHECK:STDOUT: --- fail_todo_import_const_short_pointer.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
 // CHECK:STDOUT:   %int_16: Core.IntLiteral = int_value 16 [concrete]
 // CHECK:STDOUT:   %i16: type = class_type @Int, @Int(%int_16) [concrete]
 // CHECK:STDOUT:   %ptr.251: type = ptr_type %i16 [concrete]
-// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
-// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %foo.decl
+// CHECK:STDOUT:     .foo = <error>
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
 // CHECK:STDOUT:   %a.ref: ref %i16 = name_ref a, %a
-// CHECK:STDOUT:   %addr.loc9: %ptr.251 = addr_of %a.ref
-// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%addr.loc9)
+// CHECK:STDOUT:   %addr.loc16: %ptr.251 = addr_of %a.ref
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/check/testdata/interop/cpp/function/param_int32.carbon b/toolchain/check/testdata/interop/cpp/function/param_int32.carbon
index 17cb4bc4f7ae..97481c47bef6 100644
--- a/toolchain/check/testdata/interop/cpp/function/param_int32.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/param_int32.carbon
@@ -255,7 +255,7 @@ fn F() {
 
 auto foo(const int a) -> void;
 
-// --- import_const_int.carbon
+// --- fail_todo_import_const_int.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -263,6 +263,13 @@ import Cpp library "const_int.h";
 
 fn F() {
   //@dump-sem-ir-begin
+  // CHECK:STDERR: fail_todo_import_const_int.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: const int` [SemanticsTodo]
+  // CHECK:STDERR:   Cpp.foo(1);
+  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR: fail_todo_import_const_int.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
+  // CHECK:STDERR:   Cpp.foo(1);
+  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR:
   Cpp.foo(1);
   //@dump-sem-ir-end
 }
@@ -352,7 +359,7 @@ fn F() {
 
 auto foo(const int* _Nonnull a) -> int;
 
-// --- import_const_int_pointer.carbon
+// --- fail_todo_import_const_int_pointer.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -361,6 +368,13 @@ import Cpp library "const_int_pointer.h";
 fn F() {
   var a : i32 = 1;
   //@dump-sem-ir-begin
+  // CHECK:STDERR: fail_todo_import_const_int_pointer.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: const int * _Nonnull` [SemanticsTodo]
+  // CHECK:STDERR:   Cpp.foo(&a);
+  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR: fail_todo_import_const_int_pointer.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
+  // CHECK:STDERR:   Cpp.foo(&a);
+  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR:
   Cpp.foo(&a);
   //@dump-sem-ir-end
 }
@@ -962,58 +976,24 @@ fn F() {
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- import_const_int.carbon
+// CHECK:STDOUT: --- fail_todo_import_const_int.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
-// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
-// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
-// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
-// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
-// CHECK:STDOUT:   %int_1.5b8: Core.IntLiteral = int_value 1 [concrete]
-// CHECK:STDOUT:   %ImplicitAs.type.205: type = facet_type <@ImplicitAs, @ImplicitAs(%i32)> [concrete]
-// CHECK:STDOUT:   %Convert.type.1b6: type = fn_type @Convert.1, @ImplicitAs(%i32) [concrete]
-// CHECK:STDOUT:   %To: Core.IntLiteral = bind_symbolic_name To, 0 [symbolic]
-// CHECK:STDOUT:   %Convert.type.0f9: type = fn_type @Convert.2, @impl.4f9(%To) [symbolic]
-// CHECK:STDOUT:   %Convert.f06: %Convert.type.0f9 = struct_value () [symbolic]
-// CHECK:STDOUT:   %ImplicitAs.impl_witness.c75: <witness> = impl_witness imports.%ImplicitAs.impl_witness_table.a2f, @impl.4f9(%int_32) [concrete]
-// CHECK:STDOUT:   %Convert.type.035: type = fn_type @Convert.2, @impl.4f9(%int_32) [concrete]
-// CHECK:STDOUT:   %Convert.956: %Convert.type.035 = struct_value () [concrete]
-// CHECK:STDOUT:   %ImplicitAs.facet: %ImplicitAs.type.205 = facet_value Core.IntLiteral, (%ImplicitAs.impl_witness.c75) [concrete]
-// CHECK:STDOUT:   %.9c3: type = fn_type_with_self_type %Convert.type.1b6, %ImplicitAs.facet [concrete]
-// CHECK:STDOUT:   %Convert.bound: <bound method> = bound_method %int_1.5b8, %Convert.956 [concrete]
-// CHECK:STDOUT:   %Convert.specific_fn: <specific function> = specific_function %Convert.956, @Convert.2(%int_32) [concrete]
-// CHECK:STDOUT:   %bound_method: <bound method> = bound_method %int_1.5b8, %Convert.specific_fn [concrete]
-// CHECK:STDOUT:   %int_1.5d2: %i32 = int_value 1 [concrete]
+// CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %foo.decl
+// CHECK:STDOUT:     .foo = <error>
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %Core.import_ref.a5b: @impl.4f9.%Convert.type (%Convert.type.0f9) = import_ref Core//prelude/parts/int, loc16_39, loaded [symbolic = @impl.4f9.%Convert (constants.%Convert.f06)]
-// CHECK:STDOUT:   %ImplicitAs.impl_witness_table.a2f = impl_witness_table (%Core.import_ref.a5b), @impl.4f9 [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
-// CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1.5b8]
-// CHECK:STDOUT:   %impl.elem0: %.9c3 = impl_witness_access constants.%ImplicitAs.impl_witness.c75, element0 [concrete = constants.%Convert.956]
-// CHECK:STDOUT:   %bound_method.loc8_11.1: <bound method> = bound_method %int_1, %impl.elem0 [concrete = constants.%Convert.bound]
-// CHECK:STDOUT:   %specific_fn: <specific function> = specific_function %impl.elem0, @Convert.2(constants.%int_32) [concrete = constants.%Convert.specific_fn]
-// CHECK:STDOUT:   %bound_method.loc8_11.2: <bound method> = bound_method %int_1, %specific_fn [concrete = constants.%bound_method]
-// CHECK:STDOUT:   %int.convert_checked: init %i32 = call %bound_method.loc8_11.2(%int_1) [concrete = constants.%int_1.5d2]
-// CHECK:STDOUT:   %.loc8_11.1: %i32 = value_of_initializer %int.convert_checked [concrete = constants.%int_1.5d2]
-// CHECK:STDOUT:   %.loc8_11.2: %i32 = converted %int_1, %.loc8_11.1 [concrete = constants.%int_1.5d2]
-// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%.loc8_11.2)
+// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %int_1: Core.IntLiteral = int_value 1 [concrete = constants.%int_1]
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1097,36 +1077,28 @@ fn F() {
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- import_const_int_pointer.carbon
+// CHECK:STDOUT: --- fail_todo_import_const_int_pointer.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
 // CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
 // CHECK:STDOUT:   %ptr.235: type = ptr_type %i32 [concrete]
-// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
-// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = %foo.decl
+// CHECK:STDOUT:     .foo = <error>
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
 // CHECK:STDOUT:   %a.ref: ref %i32 = name_ref a, %a
-// CHECK:STDOUT:   %addr.loc9: %ptr.235 = addr_of %a.ref
-// CHECK:STDOUT:   %foo.call: init %i32 = call %foo.ref(%addr.loc9)
+// CHECK:STDOUT:   %addr.loc16: %ptr.235 = addr_of %a.ref
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/check/testdata/interop/cpp/function/pointer.carbon b/toolchain/check/testdata/interop/cpp/function/pointer.carbon
index 190edcfe9358..64d2388b5a0c 100644
--- a/toolchain/check/testdata/interop/cpp/function/pointer.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/pointer.carbon
@@ -53,14 +53,7 @@ fn F() {
   //@dump-sem-ir-begin
   var s: Cpp.S = {};
   var p: Cpp.S* = &s;
-  // CHECK:STDERR: fail_todo_import_double_pointer_param.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: pointer to pointer type: S * _Nonnull` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(&p);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_double_pointer_param.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo(&p);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_double_pointer_param.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: S * _Nonnull * _Nonnull` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_double_pointer_param.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: pointer to pointer type: S * _Nonnull` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo(&p);
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_double_pointer_param.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -92,13 +85,12 @@ fn G() -> const Cpp.S;
 fn F() {
   //@dump-sem-ir-begin
   var s: const Cpp.S = G();
-  // CHECK:STDERR: fail_todo_import_const_pointer_param.carbon:[[@LINE+8]]:11: error: cannot implicitly convert expression of type `const Cpp.S*` to `Cpp.S*` [ConversionFailure]
+  // CHECK:STDERR: fail_todo_import_const_pointer_param.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: const S * _Nonnull` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo(&s);
-  // CHECK:STDERR:           ^~
-  // CHECK:STDERR: fail_todo_import_const_pointer_param.carbon:[[@LINE+5]]:11: note: type `const Cpp.S*` does not implement interface `Core.ImplicitAs(Cpp.S*)` [MissingImplInMemberAccessNote]
+  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR: fail_todo_import_const_pointer_param.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
   // CHECK:STDERR:   Cpp.foo(&s);
-  // CHECK:STDERR:           ^~
-  // CHECK:STDERR: fail_todo_import_const_pointer_param.carbon: note: initializing function parameter [InCallToFunctionParam]
+  // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR:
   Cpp.foo(&s);
   //@dump-sem-ir-end
@@ -149,14 +141,7 @@ fn IngestDoublePointer(s: Cpp.S**);
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_double_pointer_return.carbon:[[@LINE+14]]:23: error: semantics TODO: `Unsupported: pointer to pointer type: S * _Nonnull` [SemanticsTodo]
-  // CHECK:STDERR:   IngestDoublePointer(Cpp.foo());
-  // CHECK:STDERR:                       ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_double_pointer_return.carbon:[[@LINE+11]]:23: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   IngestDoublePointer(Cpp.foo());
-  // CHECK:STDERR:                       ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_double_pointer_return.carbon:[[@LINE+7]]:23: error: semantics TODO: `Unsupported: return type: S * _Nonnull * _Nonnull` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_double_pointer_return.carbon:[[@LINE+7]]:23: error: semantics TODO: `Unsupported: pointer to pointer type: S * _Nonnull` [SemanticsTodo]
   // CHECK:STDERR:   IngestDoublePointer(Cpp.foo());
   // CHECK:STDERR:                       ^~~~~~~
   // CHECK:STDERR: fail_todo_import_double_pointer_return.carbon:[[@LINE+4]]:23: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -188,15 +173,12 @@ fn IngestConstPointer(s: const Cpp.S*);
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_const_pointer_return.carbon:[[@LINE+10]]:22: error: cannot implicitly convert expression of type `Cpp.S*` to `const Cpp.S*` [ConversionFailure]
+  // CHECK:STDERR: fail_todo_import_const_pointer_return.carbon:[[@LINE+7]]:22: error: semantics TODO: `Unsupported: return type: const S * _Nonnull` [SemanticsTodo]
   // CHECK:STDERR:   IngestConstPointer(Cpp.foo());
-  // CHECK:STDERR:                      ^~~~~~~~~
-  // CHECK:STDERR: fail_todo_import_const_pointer_return.carbon:[[@LINE+7]]:22: note: type `Cpp.S*` does not implement interface `Core.ImplicitAs(const Cpp.S*)` [MissingImplInMemberAccessNote]
+  // CHECK:STDERR:                      ^~~~~~~
+  // CHECK:STDERR: fail_todo_import_const_pointer_return.carbon:[[@LINE+4]]:22: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
   // CHECK:STDERR:   IngestConstPointer(Cpp.foo());
-  // CHECK:STDERR:                      ^~~~~~~~~
-  // CHECK:STDERR: fail_todo_import_const_pointer_return.carbon:[[@LINE-10]]:23: note: initializing function parameter [InCallToFunctionParam]
-  // CHECK:STDERR: fn IngestConstPointer(s: const Cpp.S*);
-  // CHECK:STDERR:                       ^~~~~~~~~~~~~~~
+  // CHECK:STDERR:                      ^~~~~~~
   // CHECK:STDERR:
   IngestConstPointer(Cpp.foo());
   Cpp.foo();
@@ -222,14 +204,7 @@ import Cpp library "nullable_pointer_param.h";
 fn F() {
   //@dump-sem-ir-begin
   var s: Cpp.S = {};
-  // CHECK:STDERR: fail_todo_import_nullable_pointer_param.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: nullable pointer: S *` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(&s);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_nullable_pointer_param.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo(&s);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_nullable_pointer_param.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: S *` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_nullable_pointer_param.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: nullable pointer: S *` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo(&s);
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_nullable_pointer_param.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -321,6 +296,8 @@ fn F() {
 // CHECK:STDOUT:   %S.val: %S = struct_value () [concrete]
 // CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
 // CHECK:STDOUT:   %pattern_type.259: type = pattern_type %ptr.5c7 [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT:   %ptr.dfe: type = ptr_type %ptr.5c7 [concrete]
 // CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
 // CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
@@ -344,10 +321,15 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .S = %S.decl
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
 // CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
 // CHECK:STDOUT: }
@@ -383,10 +365,11 @@ fn F() {
 // CHECK:STDOUT:     %ptr: type = ptr_type %S.ref.loc9 [concrete = constants.%ptr.5c7]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %p: ref %ptr.5c7 = bind_name p, %p.var
-// CHECK:STDOUT:   %Cpp.ref.loc24: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %Cpp.ref.loc17: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %p.ref: ref %ptr.5c7 = name_ref p, %p
-// CHECK:STDOUT:   %addr.loc24: %ptr.dfe = addr_of %p.ref
+// CHECK:STDOUT:   %addr.loc17: %ptr.dfe = addr_of %p.ref
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
 // CHECK:STDOUT:   %impl.elem0.loc9: %.33b = impl_witness_access constants.%Destroy.impl_witness.79a, element0 [concrete = constants.%Op.64b]
 // CHECK:STDOUT:   %bound_method.loc9_3.1: <bound method> = bound_method %p.var, %impl.elem0.loc9
 // CHECK:STDOUT:   %specific_fn.loc9: <specific function> = specific_function %impl.elem0.loc9, @Op.2(constants.%ptr.5c7) [concrete = constants.%Op.specific_fn.131]
@@ -411,9 +394,6 @@ fn F() {
 // CHECK:STDOUT:   %G.type: type = fn_type @G [concrete]
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
 // CHECK:STDOUT:   %G: %G.type = struct_value () [concrete]
-// CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
-// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
-// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT:   %ptr.ff5: type = ptr_type %const [concrete]
 // CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
 // CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
@@ -431,15 +411,10 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .S = %S.decl
-// CHECK:STDOUT:     .foo = %foo.decl
+// CHECK:STDOUT:     .foo = <error>
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
-// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   } {
-// CHECK:STDOUT:     <elided>
-// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
 // CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
 // CHECK:STDOUT: }
@@ -461,12 +436,10 @@ fn F() {
 // CHECK:STDOUT:     %const: type = const_type %S.ref [concrete = constants.%const]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %s: ref %const = bind_name s, %s.var
-// CHECK:STDOUT:   %Cpp.ref.loc19: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %Cpp.ref.loc18: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
 // CHECK:STDOUT:   %s.ref: ref %const = name_ref s, %s
-// CHECK:STDOUT:   %addr.loc19: %ptr.ff5 = addr_of %s.ref
-// CHECK:STDOUT:   %.loc19: %ptr.5c7 = converted %addr.loc19, <error> [concrete = <error>]
-// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
+// CHECK:STDOUT:   %addr.loc18: %ptr.ff5 = addr_of %s.ref
 // CHECK:STDOUT:   %impl.elem0.loc10_3.1: %.af2 = impl_witness_access constants.%Destroy.impl_witness.4d8, element0 [concrete = constants.%Op.af7]
 // CHECK:STDOUT:   %bound_method.loc10_3.1: <bound method> = bound_method %.loc10_3, %impl.elem0.loc10_3.1
 // CHECK:STDOUT:   %specific_fn.loc10_3.1: <specific function> = specific_function %impl.elem0.loc10_3.1, @Op.2(constants.%const) [concrete = constants.%Op.specific_fn]
@@ -530,38 +503,6 @@ fn F() {
 // CHECK:STDOUT:   %IngestDoublePointer.type: type = fn_type @IngestDoublePointer [concrete]
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
 // CHECK:STDOUT:   %IngestDoublePointer: %IngestDoublePointer.type = struct_value () [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .S = %S.decl
-// CHECK:STDOUT:     .foo = <error>
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %IngestDoublePointer.ref: %IngestDoublePointer.type = name_ref IngestDoublePointer, file.%IngestDoublePointer.decl [concrete = constants.%IngestDoublePointer]
-// CHECK:STDOUT:   %Cpp.ref.loc24: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref.loc24: <error> = name_ref foo, <error> [concrete = <error>]
-// CHECK:STDOUT:   %IngestDoublePointer.call: init %empty_tuple.type = call %IngestDoublePointer.ref(<error>)
-// CHECK:STDOUT:   %Cpp.ref.loc25: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref.loc25: <error> = name_ref foo, <error> [concrete = <error>]
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_const_pointer_return.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %S: type = class_type @S [concrete]
-// CHECK:STDOUT:   %const: type = const_type %S [concrete]
-// CHECK:STDOUT:   %ptr.ff5: type = ptr_type %const [concrete]
-// CHECK:STDOUT:   %IngestConstPointer.type: type = fn_type @IngestConstPointer [concrete]
-// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
-// CHECK:STDOUT:   %IngestConstPointer: %IngestConstPointer.type = struct_value () [concrete]
-// CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
 // CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
 // CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
@@ -582,15 +523,43 @@ fn F() {
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %IngestDoublePointer.ref: %IngestDoublePointer.type = name_ref IngestDoublePointer, file.%IngestDoublePointer.decl [concrete = constants.%IngestDoublePointer]
+// CHECK:STDOUT:   %Cpp.ref.loc17: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref.loc17: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %foo.call.loc17: init <error> = call %foo.ref.loc17()
+// CHECK:STDOUT:   %IngestDoublePointer.call: init %empty_tuple.type = call %IngestDoublePointer.ref(<error>)
+// CHECK:STDOUT:   %Cpp.ref.loc18: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref.loc18: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %foo.call.loc18: init <error> = call %foo.ref.loc18()
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_todo_import_const_pointer_return.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %S: type = class_type @S [concrete]
+// CHECK:STDOUT:   %IngestConstPointer.type: type = fn_type @IngestConstPointer [concrete]
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %IngestConstPointer: %IngestConstPointer.type = struct_value () [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .S = %S.decl
+// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %IngestConstPointer.ref: %IngestConstPointer.type = name_ref IngestConstPointer, file.%IngestConstPointer.decl [concrete = constants.%IngestConstPointer]
-// CHECK:STDOUT:   %Cpp.ref.loc20: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref.loc20: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
-// CHECK:STDOUT:   %foo.call.loc20: init %ptr.5c7 = call %foo.ref.loc20()
-// CHECK:STDOUT:   %.loc20: %ptr.ff5 = converted %foo.call.loc20, <error> [concrete = <error>]
+// CHECK:STDOUT:   %Cpp.ref.loc17: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref.loc17: <error> = name_ref foo, <error> [concrete = <error>]
 // CHECK:STDOUT:   %IngestConstPointer.call: init %empty_tuple.type = call %IngestConstPointer.ref(<error>)
-// CHECK:STDOUT:   %Cpp.ref.loc21: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref.loc21: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
-// CHECK:STDOUT:   %foo.call.loc21: init %ptr.5c7 = call %foo.ref.loc21()
+// CHECK:STDOUT:   %Cpp.ref.loc18: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref.loc18: <error> = name_ref foo, <error> [concrete = <error>]
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -602,6 +571,8 @@ fn F() {
 // CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
 // CHECK:STDOUT:   %pattern_type.7da: type = pattern_type %S [concrete]
 // CHECK:STDOUT:   %S.val: %S = struct_value () [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT:   %ptr.5c7: type = ptr_type %S [concrete]
 // CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
 // CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
@@ -619,10 +590,15 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .S = %S.decl
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
 // CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
 // CHECK:STDOUT: }
@@ -644,10 +620,11 @@ fn F() {
 // CHECK:STDOUT:     %S.ref: type = name_ref S, imports.%S.decl [concrete = constants.%S]
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %s: ref %S = bind_name s, %s.var
-// CHECK:STDOUT:   %Cpp.ref.loc23: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %Cpp.ref.loc16: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %s.ref: ref %S = name_ref s, %s
-// CHECK:STDOUT:   %addr.loc23: %ptr.5c7 = addr_of %s.ref
+// CHECK:STDOUT:   %addr.loc16: %ptr.5c7 = addr_of %s.ref
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
 // CHECK:STDOUT:   %impl.elem0: %.271 = impl_witness_access constants.%Destroy.impl_witness.2d2, element0 [concrete = constants.%Op.ab5]
 // CHECK:STDOUT:   %bound_method.loc8_3.1: <bound method> = bound_method %s.var, %impl.elem0
 // CHECK:STDOUT:   %specific_fn: <specific function> = specific_function %impl.elem0, @Op.2(constants.%S) [concrete = constants.%Op.specific_fn]
diff --git a/toolchain/check/testdata/interop/cpp/function/struct.carbon b/toolchain/check/testdata/interop/cpp/function/struct.carbon
index 856ea1be5786..783be7d54cd4 100644
--- a/toolchain/check/testdata/interop/cpp/function/struct.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/struct.carbon
@@ -27,14 +27,7 @@ library "[[@TEST_NAME]]";
 import Cpp library "decl_value_param_type.h";
 
 fn F() {
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: S` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo({});
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -63,13 +56,6 @@ fn F() {
   // CHECK:STDERR:               ^
   // CHECK:STDERR:
   let s: Cpp.S;
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type_previously_imported.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: S` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(s);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type_previously_imported.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo(s);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo(s);
 }
 
@@ -91,14 +77,7 @@ library "[[@TEST_NAME]]";
 import Cpp library "double_decl_value_param_type.h";
 
 fn F() {
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo1({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo1` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo1({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: S` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo1({});
   // CHECK:STDERR:   ^~~~~~~~
   // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo1` [InCppNameLookup]
@@ -106,13 +85,6 @@ fn F() {
   // CHECK:STDERR:   ^~~~~~~~
   // CHECK:STDERR:
   Cpp.foo1({});
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: S` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo2({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo2` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo2({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR:
   Cpp.foo2({});
 }
 
@@ -300,13 +272,6 @@ import Cpp library "decl_pointer_param_type.h";
 // CHECK:STDERR:
 fn F(s: Cpp.S*) {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_decl_pointer_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: S * _Nonnull` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(s);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_pointer_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo(s);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo(s);
   //@dump-sem-ir-end
 }
@@ -350,14 +315,7 @@ library "[[@TEST_NAME]]";
 import Cpp library "decl_value_return_type.h";
 
 fn F() {
-  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: return type: S` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo();
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -407,14 +365,7 @@ import Cpp library "decl_pointer_return_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: return type: S * _Nonnull` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo();
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -473,10 +424,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .S = %S.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -532,10 +481,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .S = %S.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -591,10 +538,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .S = %S.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -879,21 +824,30 @@ fn F() {
 // CHECK:STDOUT: --- fail_todo_import_decl_pointer_param_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .S = <error>
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F(%s.param: <error>) {
 // CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %Cpp.ref.loc22: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %Cpp.ref.loc15: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %s.ref: <error> = name_ref s, %s
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -954,10 +908,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .S = %S.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
@@ -986,20 +938,27 @@ fn F() {
 // CHECK:STDOUT: --- fail_todo_import_decl_pointer_return_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
-// CHECK:STDOUT:     .S = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %foo.call: init <error> = call %foo.ref()
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
@@ -1015,10 +974,8 @@ fn F() {
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .foo = %foo.decl
-// CHECK:STDOUT:     .S = %S.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
-// CHECK:STDOUT:   %S.decl: type = class_decl @S [concrete = constants.%S] {} {}
 // CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
 // CHECK:STDOUT:     <elided>
 // CHECK:STDOUT:   } {
diff --git a/toolchain/check/testdata/interop/cpp/function/union.carbon b/toolchain/check/testdata/interop/cpp/function/union.carbon
index 2f2342a94627..317caa47ff86 100644
--- a/toolchain/check/testdata/interop/cpp/function/union.carbon
+++ b/toolchain/check/testdata/interop/cpp/function/union.carbon
@@ -2,7 +2,7 @@
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
-// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/none.carbon
+// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/destroy.carbon
 //
 // AUTOUPDATE
 // TIP: To test this file alone, run:
@@ -28,8 +28,7 @@ import Cpp library "decl_value_param_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // TODO: This should fail on the fact `U` is declared and not defined.
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo({});
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_decl_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -59,13 +58,6 @@ fn F() {
   // CHECK:STDERR:               ^
   // CHECK:STDERR:
   let u: Cpp.U;
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type_previously_imported.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(u);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_value_param_type_previously_imported.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo(u);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo(u);
 }
 
@@ -87,7 +79,7 @@ library "[[@TEST_NAME]]";
 import Cpp library "double_decl_value_param_type.h";
 
 fn F() {
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo1({});
   // CHECK:STDERR:   ^~~~~~~~
   // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo1` [InCppNameLookup]
@@ -95,13 +87,6 @@ fn F() {
   // CHECK:STDERR:   ^~~~~~~~
   // CHECK:STDERR:
   Cpp.foo1({});
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo2({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR: fail_todo_import_double_decl_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo2` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo2({});
-  // CHECK:STDERR:   ^~~~~~~~
-  // CHECK:STDERR:
   Cpp.foo2({});
 }
 
@@ -115,7 +100,7 @@ union U {};
 
 auto foo(U) -> void;
 
-// --- fail_todo_import_definition_no_data_members_value_param_type.carbon
+// --- import_definition_no_data_members_value_param_type.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -123,13 +108,6 @@ import Cpp library "definition_no_data_members_value_param_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_definition_no_data_members_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_no_data_members_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo({});
   //@dump-sem-ir-end
 }
@@ -148,7 +126,7 @@ union U {
 
 auto foo(U) -> void;
 
-// --- fail_todo_import_definition_single_data_member_value_param_type.carbon
+// --- fail_import_definition_single_data_member_value_param_type.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -156,10 +134,10 @@ import Cpp library "definition_single_data_member_value_param_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_definition_single_data_member_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U` [SemanticsTodo]
+  // CHECK:STDERR: fail_import_definition_single_data_member_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Non-empty union` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo({});
   // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_single_data_member_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
+  // CHECK:STDERR: fail_import_definition_single_data_member_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
   // CHECK:STDERR:   Cpp.foo({});
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR:
@@ -183,7 +161,7 @@ union U {
 
 auto foo(U) -> void;
 
-// --- fail_todo_import_definition_multiple_data_members_value_param_type.carbon
+// --- fail_import_definition_multiple_data_members_value_param_type.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -191,10 +169,10 @@ import Cpp library "definition_multiple_data_members_value_param_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_definition_multiple_data_members_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U` [SemanticsTodo]
+  // CHECK:STDERR: fail_import_definition_multiple_data_members_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Non-empty union` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo({});
   // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_multiple_data_members_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
+  // CHECK:STDERR: fail_import_definition_multiple_data_members_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
   // CHECK:STDERR:   Cpp.foo({});
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR:
@@ -212,7 +190,7 @@ namespace N { union U {}; }
 
 auto foo(N::U) -> void;
 
-// --- fail_todo_import_definition_in_namespace_value_param_type.carbon
+// --- import_definition_in_namespace_value_param_type.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -220,13 +198,6 @@ import Cpp library "definition_in_namespace_value_param_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_definition_in_namespace_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: N::U` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_in_namespace_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo({});
   //@dump-sem-ir-end
 }
@@ -242,7 +213,7 @@ namespace N1 {
   auto foo(N2::U) -> void;
 }
 
-// --- fail_todo_import_definition_in_relative_namespace_value_param_type.carbon
+// --- import_definition_in_relative_namespace_value_param_type.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -250,13 +221,6 @@ import Cpp library "definition_in_relative_namespace_value_param_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_definition_in_relative_namespace_value_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: N2::U` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.N1.foo({});
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_in_relative_namespace_value_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.N1.foo({});
-  // CHECK:STDERR:   ^~~~~~~~~~
-  // CHECK:STDERR:
   Cpp.N1.foo({});
   //@dump-sem-ir-end
 }
@@ -273,7 +237,7 @@ union U {
 
 auto foo(U) -> void;
 
-// --- fail_todo_import_definition_and_static_method_call_before.carbon
+// --- import_definition_and_static_method_call_before.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -282,18 +246,11 @@ import Cpp library "definition_with_static_method.h";
 fn F() {
   //@dump-sem-ir-begin
   Cpp.U.bar();
-  // CHECK:STDERR: fail_todo_import_definition_and_static_method_call_before.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_and_static_method_call_before.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo({});
   //@dump-sem-ir-end
 }
 
-// --- fail_todo_import_definition_and_static_method_call_after.carbon
+// --- import_definition_and_static_method_call_after.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -301,13 +258,6 @@ import Cpp library "definition_with_static_method.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_definition_and_static_method_call_after.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_and_static_method_call_after.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo({});
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo({});
   Cpp.U.bar();
   //@dump-sem-ir-end
@@ -338,13 +288,6 @@ import Cpp library "decl_pointer_param_type.h";
 // CHECK:STDERR:
 fn F(u: Cpp.U*) {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_decl_pointer_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U * _Nonnull` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(u);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_pointer_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo(u);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo(u);
   //@dump-sem-ir-end
 }
@@ -359,7 +302,7 @@ union U {};
 
 auto foo(U* _Nonnull) -> void;
 
-// --- fail_todo_import_definition_pointer_param_type.carbon
+// --- import_definition_pointer_param_type.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -367,13 +310,6 @@ import Cpp library "definition_pointer_param_type.h";
 
 fn F(u: Cpp.U*) {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_definition_pointer_param_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: parameter type: U * _Nonnull` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo(u);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_pointer_param_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo(u);
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo(u);
   //@dump-sem-ir-end
 }
@@ -395,8 +331,7 @@ library "[[@TEST_NAME]]";
 import Cpp library "decl_value_return_type.h";
 
 fn F() {
-  // TODO: This should fail on the fact `U` is declared and not defined.
-  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: return type: U` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: Record declarations without a definition` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo();
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_decl_value_return_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -416,7 +351,7 @@ union U {};
 
 auto foo() -> U;
 
-// --- fail_todo_import_definition_value_return_type.carbon
+// --- import_definition_value_return_type.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -424,13 +359,6 @@ import Cpp library "definition_value_return_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_definition_value_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: return type: U` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_value_return_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo();
   //@dump-sem-ir-end
 }
@@ -453,14 +381,7 @@ import Cpp library "decl_pointer_return_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+14]]:3: error: semantics TODO: `Unsupported: nullable pointer: U *` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+11]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: return type: U *` [SemanticsTodo]
+  // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: nullable pointer: U *` [SemanticsTodo]
   // CHECK:STDERR:   Cpp.foo();
   // CHECK:STDERR:   ^~~~~~~
   // CHECK:STDERR: fail_todo_import_decl_pointer_return_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
@@ -481,7 +402,7 @@ union U {};
 
 auto foo() -> U* _Nonnull;
 
-// --- fail_todo_import_definition_pointer_return_type.carbon
+// --- import_definition_pointer_return_type.carbon
 
 library "[[@TEST_NAME]]";
 
@@ -489,13 +410,6 @@ import Cpp library "definition_pointer_return_type.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_definition_pointer_return_type.carbon:[[@LINE+7]]:3: error: semantics TODO: `Unsupported: return type: U * _Nonnull` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_definition_pointer_return_type.carbon:[[@LINE+4]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
   Cpp.foo();
   //@dump-sem-ir-end
 }
@@ -503,112 +417,228 @@ fn F() {
 // CHECK:STDOUT: --- fail_todo_import_decl_value_param_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
-// CHECK:STDOUT:   %.loc16: %empty_struct_type = struct_literal ()
-// CHECK:STDOUT:   <elided>
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_no_data_members_value_param_type.carbon
-// CHECK:STDOUT:
-// CHECK:STDOUT: constants {
-// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
-// CHECK:STDOUT: }
-// CHECK:STDOUT:
-// CHECK:STDOUT: fn @F() {
-// CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %.loc15: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_single_data_member_value_param_type.carbon
+// CHECK:STDOUT: --- import_definition_no_data_members_value_param_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %U: type = class_type @U [concrete]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
+// CHECK:STDOUT:   %U.val: %U = struct_value () [concrete]
+// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
+// CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T, 0 [symbolic]
+// CHECK:STDOUT:   %Op.type.bc9: type = fn_type @Op.2, @impl(%T) [symbolic]
+// CHECK:STDOUT:   %Op.46f: %Op.type.bc9 = struct_value () [symbolic]
+// CHECK:STDOUT:   %Destroy.impl_witness.abf: <witness> = impl_witness imports.%Destroy.impl_witness_table, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.type.0b7: type = fn_type @Op.2, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.2fa: %Op.type.0b7 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.86f: type = ptr_type %U [concrete]
+// CHECK:STDOUT:   %Destroy.facet: %Destroy.type = facet_value %U, (%Destroy.impl_witness.abf) [concrete]
+// CHECK:STDOUT:   %.487: type = fn_type_with_self_type %Op.type.bae, %Destroy.facet [concrete]
+// CHECK:STDOUT:   %Op.specific_fn: <specific function> = specific_function %Op.2fa, @Op.2(%U) [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .foo = %foo.decl
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
+// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %.loc8_12.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %.loc8_12.2: ref %U = temporary_storage
+// CHECK:STDOUT:   %.loc8_12.3: init %U = class_init (), %.loc8_12.2 [concrete = constants.%U.val]
+// CHECK:STDOUT:   %.loc8_12.4: ref %U = temporary %.loc8_12.2, %.loc8_12.3
+// CHECK:STDOUT:   %.loc8_12.5: ref %U = converted %.loc8_12.1, %.loc8_12.4
+// CHECK:STDOUT:   %.loc8_12.6: %U = bind_value %.loc8_12.5
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%.loc8_12.6)
+// CHECK:STDOUT:   %impl.elem0: %.487 = impl_witness_access constants.%Destroy.impl_witness.abf, element0 [concrete = constants.%Op.2fa]
+// CHECK:STDOUT:   %bound_method.loc8_12.1: <bound method> = bound_method %.loc8_12.2, %impl.elem0
+// CHECK:STDOUT:   %specific_fn: <specific function> = specific_function %impl.elem0, @Op.2(constants.%U) [concrete = constants.%Op.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc8_12.2: <bound method> = bound_method %.loc8_12.2, %specific_fn
+// CHECK:STDOUT:   %addr: %ptr.86f = addr_of %.loc8_12.2
+// CHECK:STDOUT:   %no_op: init %empty_tuple.type = call %bound_method.loc8_12.2(%addr)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- fail_import_definition_single_data_member_value_param_type.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %.loc15: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_multiple_data_members_value_param_type.carbon
+// CHECK:STDOUT: --- fail_import_definition_multiple_data_members_value_param_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %.loc15: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_in_namespace_value_param_type.carbon
+// CHECK:STDOUT: --- import_definition_in_namespace_value_param_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %U: type = class_type @U [concrete]
 // CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
+// CHECK:STDOUT:   %U.val: %U = struct_value () [concrete]
+// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
+// CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T, 0 [symbolic]
+// CHECK:STDOUT:   %Op.type.bc9: type = fn_type @Op.2, @impl(%T) [symbolic]
+// CHECK:STDOUT:   %Op.46f: %Op.type.bc9 = struct_value () [symbolic]
+// CHECK:STDOUT:   %Destroy.impl_witness.493: <witness> = impl_witness imports.%Destroy.impl_witness_table, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.type.2e1: type = fn_type @Op.2, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.d5d: %Op.type.2e1 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.87e: type = ptr_type %U [concrete]
+// CHECK:STDOUT:   %Destroy.facet: %Destroy.type = facet_value %U, (%Destroy.impl_witness.493) [concrete]
+// CHECK:STDOUT:   %.c67: type = fn_type_with_self_type %Op.type.bae, %Destroy.facet [concrete]
+// CHECK:STDOUT:   %Op.specific_fn: <specific function> = specific_function %Op.d5d, @Op.2(%U) [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
+// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
-// CHECK:STDOUT:   %.loc15: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %.loc8_12.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %.loc8_12.2: ref %U = temporary_storage
+// CHECK:STDOUT:   %.loc8_12.3: init %U = class_init (), %.loc8_12.2 [concrete = constants.%U.val]
+// CHECK:STDOUT:   %.loc8_12.4: ref %U = temporary %.loc8_12.2, %.loc8_12.3
+// CHECK:STDOUT:   %.loc8_12.5: ref %U = converted %.loc8_12.1, %.loc8_12.4
+// CHECK:STDOUT:   %.loc8_12.6: %U = bind_value %.loc8_12.5
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%.loc8_12.6)
+// CHECK:STDOUT:   %impl.elem0: %.c67 = impl_witness_access constants.%Destroy.impl_witness.493, element0 [concrete = constants.%Op.d5d]
+// CHECK:STDOUT:   %bound_method.loc8_12.1: <bound method> = bound_method %.loc8_12.2, %impl.elem0
+// CHECK:STDOUT:   %specific_fn: <specific function> = specific_function %impl.elem0, @Op.2(constants.%U) [concrete = constants.%Op.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc8_12.2: <bound method> = bound_method %.loc8_12.2, %specific_fn
+// CHECK:STDOUT:   %addr: %ptr.87e = addr_of %.loc8_12.2
+// CHECK:STDOUT:   %no_op: init %empty_tuple.type = call %bound_method.loc8_12.2(%addr)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_in_relative_namespace_value_param_type.carbon
+// CHECK:STDOUT: --- import_definition_in_relative_namespace_value_param_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %U: type = class_type @U [concrete]
 // CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
+// CHECK:STDOUT:   %U.val: %U = struct_value () [concrete]
+// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
+// CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T, 0 [symbolic]
+// CHECK:STDOUT:   %Op.type.bc9: type = fn_type @Op.2, @impl(%T) [symbolic]
+// CHECK:STDOUT:   %Op.46f: %Op.type.bc9 = struct_value () [symbolic]
+// CHECK:STDOUT:   %Destroy.impl_witness.583: <witness> = impl_witness imports.%Destroy.impl_witness_table, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.type.ee1: type = fn_type @Op.2, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.28c: %Op.type.ee1 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.8c1: type = ptr_type %U [concrete]
+// CHECK:STDOUT:   %Destroy.facet: %Destroy.type = facet_value %U, (%Destroy.impl_witness.583) [concrete]
+// CHECK:STDOUT:   %.3b3: type = fn_type_with_self_type %Op.type.bae, %Destroy.facet [concrete]
+// CHECK:STDOUT:   %Op.specific_fn: <specific function> = specific_function %Op.28c, @Op.2(%U) [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
@@ -617,21 +647,40 @@ fn F() {
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %N1: <namespace> = namespace [concrete] {
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
+// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:   %N1.ref: <namespace> = name_ref N1, imports.%N1 [concrete = imports.%N1]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
-// CHECK:STDOUT:   %.loc15: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %.loc8_15.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %.loc8_15.2: ref %U = temporary_storage
+// CHECK:STDOUT:   %.loc8_15.3: init %U = class_init (), %.loc8_15.2 [concrete = constants.%U.val]
+// CHECK:STDOUT:   %.loc8_15.4: ref %U = temporary %.loc8_15.2, %.loc8_15.3
+// CHECK:STDOUT:   %.loc8_15.5: ref %U = converted %.loc8_15.1, %.loc8_15.4
+// CHECK:STDOUT:   %.loc8_15.6: %U = bind_value %.loc8_15.5
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%.loc8_15.6)
+// CHECK:STDOUT:   %impl.elem0: %.3b3 = impl_witness_access constants.%Destroy.impl_witness.583, element0 [concrete = constants.%Op.28c]
+// CHECK:STDOUT:   %bound_method.loc8_15.1: <bound method> = bound_method %.loc8_15.2, %impl.elem0
+// CHECK:STDOUT:   %specific_fn: <specific function> = specific_function %impl.elem0, @Op.2(constants.%U) [concrete = constants.%Op.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc8_15.2: <bound method> = bound_method %.loc8_15.2, %specific_fn
+// CHECK:STDOUT:   %addr: %ptr.8c1 = addr_of %.loc8_15.2
+// CHECK:STDOUT:   %no_op: init %empty_tuple.type = call %bound_method.loc8_15.2(%addr)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_and_static_method_call_before.carbon
+// CHECK:STDOUT: --- import_definition_and_static_method_call_before.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
@@ -639,16 +688,38 @@ fn F() {
 // CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
 // CHECK:STDOUT:   %bar.type: type = fn_type @bar [concrete]
 // CHECK:STDOUT:   %bar: %bar.type = struct_value () [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
+// CHECK:STDOUT:   %U.val: %U = struct_value () [concrete]
+// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
+// CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T, 0 [symbolic]
+// CHECK:STDOUT:   %Op.type.bc9: type = fn_type @Op.2, @impl(%T) [symbolic]
+// CHECK:STDOUT:   %Op.46f: %Op.type.bc9 = struct_value () [symbolic]
+// CHECK:STDOUT:   %Destroy.impl_witness.abf: <witness> = impl_witness imports.%Destroy.impl_witness_table, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.type.0b7: type = fn_type @Op.2, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.2fa: %Op.type.0b7 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.86f: type = ptr_type %U [concrete]
+// CHECK:STDOUT:   %Destroy.facet: %Destroy.type = facet_value %U, (%Destroy.impl_witness.abf) [concrete]
+// CHECK:STDOUT:   %.487: type = fn_type_with_self_type %Op.type.bae, %Destroy.facet [concrete]
+// CHECK:STDOUT:   %Op.specific_fn: <specific function> = specific_function %Op.2fa, @Op.2(%U) [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .U = %U.decl
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %U.decl: type = class_decl @U [concrete = constants.%U] {} {}
 // CHECK:STDOUT:   %bar.decl: %bar.type = fn_decl @bar [concrete = constants.%bar] {} {}
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
+// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
@@ -658,144 +729,257 @@ fn F() {
 // CHECK:STDOUT:   %U.ref: type = name_ref U, imports.%U.decl [concrete = constants.%U]
 // CHECK:STDOUT:   %bar.ref: %bar.type = name_ref bar, imports.%bar.decl [concrete = constants.%bar]
 // CHECK:STDOUT:   %bar.call: init %empty_tuple.type = call %bar.ref()
-// CHECK:STDOUT:   %Cpp.ref.loc16: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
-// CHECK:STDOUT:   %.loc16: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %Cpp.ref.loc9: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %.loc9_12.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %.loc9_12.2: ref %U = temporary_storage
+// CHECK:STDOUT:   %.loc9_12.3: init %U = class_init (), %.loc9_12.2 [concrete = constants.%U.val]
+// CHECK:STDOUT:   %.loc9_12.4: ref %U = temporary %.loc9_12.2, %.loc9_12.3
+// CHECK:STDOUT:   %.loc9_12.5: ref %U = converted %.loc9_12.1, %.loc9_12.4
+// CHECK:STDOUT:   %.loc9_12.6: %U = bind_value %.loc9_12.5
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%.loc9_12.6)
+// CHECK:STDOUT:   %impl.elem0: %.487 = impl_witness_access constants.%Destroy.impl_witness.abf, element0 [concrete = constants.%Op.2fa]
+// CHECK:STDOUT:   %bound_method.loc9_12.1: <bound method> = bound_method %.loc9_12.2, %impl.elem0
+// CHECK:STDOUT:   %specific_fn: <specific function> = specific_function %impl.elem0, @Op.2(constants.%U) [concrete = constants.%Op.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc9_12.2: <bound method> = bound_method %.loc9_12.2, %specific_fn
+// CHECK:STDOUT:   %addr: %ptr.86f = addr_of %.loc9_12.2
+// CHECK:STDOUT:   %no_op: init %empty_tuple.type = call %bound_method.loc9_12.2(%addr)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_and_static_method_call_after.carbon
+// CHECK:STDOUT: --- import_definition_and_static_method_call_after.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
-// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
 // CHECK:STDOUT:   %U: type = class_type @U [concrete]
+// CHECK:STDOUT:   %empty_struct_type: type = struct_type {} [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
+// CHECK:STDOUT:   %U.val: %U = struct_value () [concrete]
 // CHECK:STDOUT:   %bar.type: type = fn_type @bar [concrete]
 // CHECK:STDOUT:   %bar: %bar.type = struct_value () [concrete]
+// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
+// CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T, 0 [symbolic]
+// CHECK:STDOUT:   %Op.type.bc9: type = fn_type @Op.2, @impl(%T) [symbolic]
+// CHECK:STDOUT:   %Op.46f: %Op.type.bc9 = struct_value () [symbolic]
+// CHECK:STDOUT:   %Destroy.impl_witness.abf: <witness> = impl_witness imports.%Destroy.impl_witness_table, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.type.0b7: type = fn_type @Op.2, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.2fa: %Op.type.0b7 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.86f: type = ptr_type %U [concrete]
+// CHECK:STDOUT:   %Destroy.facet: %Destroy.type = facet_value %U, (%Destroy.impl_witness.abf) [concrete]
+// CHECK:STDOUT:   %.487: type = fn_type_with_self_type %Op.type.bae, %Destroy.facet [concrete]
+// CHECK:STDOUT:   %Op.specific_fn: <specific function> = specific_function %Op.2fa, @Op.2(%U) [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     .U = %U.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %U.decl: type = class_decl @U [concrete = constants.%U] {} {}
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT:   %bar.decl: %bar.type = fn_decl @bar [concrete = constants.%bar] {} {}
+// CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
+// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %Cpp.ref.loc15: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
-// CHECK:STDOUT:   %.loc15: %empty_struct_type = struct_literal ()
-// CHECK:STDOUT:   %Cpp.ref.loc16: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %Cpp.ref.loc8: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %.loc8_12.1: %empty_struct_type = struct_literal ()
+// CHECK:STDOUT:   %.loc8_12.2: ref %U = temporary_storage
+// CHECK:STDOUT:   %.loc8_12.3: init %U = class_init (), %.loc8_12.2 [concrete = constants.%U.val]
+// CHECK:STDOUT:   %.loc8_12.4: ref %U = temporary %.loc8_12.2, %.loc8_12.3
+// CHECK:STDOUT:   %.loc8_12.5: ref %U = converted %.loc8_12.1, %.loc8_12.4
+// CHECK:STDOUT:   %.loc8_12.6: %U = bind_value %.loc8_12.5
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%.loc8_12.6)
+// CHECK:STDOUT:   %Cpp.ref.loc9: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
 // CHECK:STDOUT:   %U.ref: type = name_ref U, imports.%U.decl [concrete = constants.%U]
 // CHECK:STDOUT:   %bar.ref: %bar.type = name_ref bar, imports.%bar.decl [concrete = constants.%bar]
 // CHECK:STDOUT:   %bar.call: init %empty_tuple.type = call %bar.ref()
+// CHECK:STDOUT:   %impl.elem0: %.487 = impl_witness_access constants.%Destroy.impl_witness.abf, element0 [concrete = constants.%Op.2fa]
+// CHECK:STDOUT:   %bound_method.loc8_12.1: <bound method> = bound_method %.loc8_12.2, %impl.elem0
+// CHECK:STDOUT:   %specific_fn: <specific function> = specific_function %impl.elem0, @Op.2(constants.%U) [concrete = constants.%Op.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc8_12.2: <bound method> = bound_method %.loc8_12.2, %specific_fn
+// CHECK:STDOUT:   %addr: %ptr.86f = addr_of %.loc8_12.2
+// CHECK:STDOUT:   %no_op: init %empty_tuple.type = call %bound_method.loc8_12.2(%addr)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_decl_pointer_param_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .U = <error>
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F(%u.param: <error>) {
 // CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %Cpp.ref.loc22: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %Cpp.ref.loc15: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %u.ref: <error> = name_ref u, %u
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(<error>)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_pointer_param_type.carbon
+// CHECK:STDOUT: --- import_definition_pointer_param_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT:   %U: type = class_type @U [concrete]
 // CHECK:STDOUT:   %ptr: type = ptr_type %U [concrete]
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
 // CHECK:STDOUT:     .U = %U.decl
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
 // CHECK:STDOUT:   %U.decl: type = class_decl @U [concrete = constants.%U] {} {}
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F(%u.param: %ptr) {
 // CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %Cpp.ref.loc15: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %Cpp.ref.loc8: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
 // CHECK:STDOUT:   %u.ref: %ptr = name_ref u, %u
+// CHECK:STDOUT:   %foo.call: init %empty_tuple.type = call %foo.ref(%u.ref)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_value_return_type.carbon
+// CHECK:STDOUT: --- import_definition_value_return_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %U: type = class_type @U [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
+// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
+// CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T, 0 [symbolic]
+// CHECK:STDOUT:   %Op.type.bc9: type = fn_type @Op.2, @impl(%T) [symbolic]
+// CHECK:STDOUT:   %Op.46f: %Op.type.bc9 = struct_value () [symbolic]
+// CHECK:STDOUT:   %Destroy.impl_witness.abf: <witness> = impl_witness imports.%Destroy.impl_witness_table, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.type.0b7: type = fn_type @Op.2, @impl(%U) [concrete]
+// CHECK:STDOUT:   %Op.2fa: %Op.type.0b7 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.86f: type = ptr_type %U [concrete]
+// CHECK:STDOUT:   %Destroy.facet: %Destroy.type = facet_value %U, (%Destroy.impl_witness.abf) [concrete]
+// CHECK:STDOUT:   %.487: type = fn_type_with_self_type %Op.type.bae, %Destroy.facet [concrete]
+// CHECK:STDOUT:   %Op.specific_fn: <specific function> = specific_function %Op.2fa, @Op.2(%U) [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
+// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %.loc8_11.1: ref %U = temporary_storage
+// CHECK:STDOUT:   %foo.call: init %U = call %foo.ref() to %.loc8_11.1
+// CHECK:STDOUT:   %.loc8_11.2: ref %U = temporary %.loc8_11.1, %foo.call
+// CHECK:STDOUT:   %impl.elem0: %.487 = impl_witness_access constants.%Destroy.impl_witness.abf, element0 [concrete = constants.%Op.2fa]
+// CHECK:STDOUT:   %bound_method.loc8_11.1: <bound method> = bound_method %.loc8_11.1, %impl.elem0
+// CHECK:STDOUT:   %specific_fn: <specific function> = specific_function %impl.elem0, @Op.2(constants.%U) [concrete = constants.%Op.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc8_11.2: <bound method> = bound_method %.loc8_11.1, %specific_fn
+// CHECK:STDOUT:   %addr: %ptr.86f = addr_of %.loc8_11.1
+// CHECK:STDOUT:   %no_op: init %empty_tuple.type = call %bound_method.loc8_11.2(%addr)
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: --- fail_todo_import_decl_pointer_return_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %foo.call: init <error> = call %foo.ref()
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
-// CHECK:STDOUT: --- fail_todo_import_definition_pointer_return_type.carbon
+// CHECK:STDOUT: --- import_definition_pointer_return_type.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %U: type = class_type @U [concrete]
+// CHECK:STDOUT:   %ptr: type = ptr_type %U [concrete]
+// CHECK:STDOUT:   %foo.type: type = fn_type @foo [concrete]
+// CHECK:STDOUT:   %foo: %foo.type = struct_value () [concrete]
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
 // CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <error>
+// CHECK:STDOUT:     .foo = %foo.decl
 // CHECK:STDOUT:     import Cpp//...
 // CHECK:STDOUT:   }
+// CHECK:STDOUT:   %foo.decl: %foo.type = fn_decl @foo [concrete = constants.%foo] {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   } {
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
 // CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   %foo.ref: %foo.type = name_ref foo, imports.%foo.decl [concrete = constants.%foo]
+// CHECK:STDOUT:   %foo.call: init %ptr = call %foo.ref()
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
diff --git a/toolchain/check/testdata/interop/cpp/include_paths.carbon b/toolchain/check/testdata/interop/cpp/include_paths.carbon
index 66ff5a3cb3ab..c2061e4bd667 100644
--- a/toolchain/check/testdata/interop/cpp/include_paths.carbon
+++ b/toolchain/check/testdata/interop/cpp/include_paths.carbon
@@ -38,16 +38,12 @@ library "[[@TEST_NAME]]";
 
 import Cpp library "stddef.h";
 
-// TODO: Once we can import typedefs, this should work.
-// CHECK:STDERR: fail_todo_import_stddef_directly.carbon:[[@LINE+11]]:8: error: semantics TODO: `Unsupported: Declaration type Typedef` [SemanticsTodo]
-// CHECK:STDERR: var n: Cpp.size_t;
+// TODO: Once we can import `unsigned long` / `unsigned long long`, this should work.
+// CHECK:STDERR: fail_todo_import_stddef_directly.carbon:[[@LINE+7]]:8: error: semantics TODO: `Unsupported: Type declaration: size_t` [SemanticsTodo]
+// CHECK:STDERR: var n: Cpp.size_t = 42;
 // CHECK:STDERR:        ^~~~~~~~~~
-// CHECK:STDERR: fail_todo_import_stddef_directly.carbon:[[@LINE+8]]:8: note: in `Cpp` name lookup for `size_t` [InCppNameLookup]
-// CHECK:STDERR: var n: Cpp.size_t;
+// CHECK:STDERR: fail_todo_import_stddef_directly.carbon:[[@LINE+4]]:8: note: in `Cpp` name lookup for `size_t` [InCppNameLookup]
+// CHECK:STDERR: var n: Cpp.size_t = 42;
 // CHECK:STDERR:        ^~~~~~~~~~
 // CHECK:STDERR:
-// CHECK:STDERR: fail_todo_import_stddef_directly.carbon:[[@LINE+4]]:8: error: member name `size_t` not found in `Cpp` [MemberNameNotFoundInInstScope]
-// CHECK:STDERR: var n: Cpp.size_t;
-// CHECK:STDERR:        ^~~~~~~~~~
-// CHECK:STDERR:
-var n: Cpp.size_t;
+var n: Cpp.size_t = 42;
diff --git a/toolchain/check/testdata/interop/cpp/typedef.carbon b/toolchain/check/testdata/interop/cpp/typedef.carbon
new file mode 100644
index 000000000000..179fe68ef887
--- /dev/null
+++ b/toolchain/check/testdata/interop/cpp/typedef.carbon
@@ -0,0 +1,235 @@
+// 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/int.carbon
+//
+// AUTOUPDATE
+// TIP: To test this file alone, run:
+// TIP:   bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/interop/cpp/typedef.carbon
+// TIP: To dump output, run:
+// TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/typedef.carbon
+
+// --- i32_typedef.h
+
+typedef int foo;
+
+using bar = int;
+
+// --- use_i32_typedef.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "i32_typedef.h";
+
+fn F() {
+  //@dump-sem-ir-begin
+  var n: Cpp.foo = 42;
+  // Types are equivalent.
+  var p: Cpp.bar* = &n;
+  //@dump-sem-ir-end
+}
+
+// --- class_typedef.h
+
+class C {};
+using D = C;
+
+// --- use_class_typedef.carbon
+
+library "[[@TEST_NAME]]";
+
+import Cpp library "class_typedef.h";
+
+fn H(var c: Cpp.C, var d: Cpp.D) {
+  //@dump-sem-ir-begin
+  // Types are equivalent.
+  var pd: Cpp.D* = &c;
+  var pc: Cpp.C* = &d;
+  //@dump-sem-ir-end
+}
+
+// CHECK:STDOUT: --- use_i32_typedef.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %int_32: Core.IntLiteral = int_value 32 [concrete]
+// CHECK:STDOUT:   %i32: type = class_type @Int, @Int(%int_32) [concrete]
+// CHECK:STDOUT:   %pattern_type.7ce: type = pattern_type %i32 [concrete]
+// CHECK:STDOUT:   %int_42.20e: Core.IntLiteral = int_value 42 [concrete]
+// CHECK:STDOUT:   %ImplicitAs.type.205: type = facet_type <@ImplicitAs, @ImplicitAs(%i32)> [concrete]
+// CHECK:STDOUT:   %Convert.type.1b6: type = fn_type @Convert.1, @ImplicitAs(%i32) [concrete]
+// CHECK:STDOUT:   %To: Core.IntLiteral = bind_symbolic_name To, 0 [symbolic]
+// CHECK:STDOUT:   %Convert.type.0f9: type = fn_type @Convert.2, @impl.4f9(%To) [symbolic]
+// CHECK:STDOUT:   %Convert.f06: %Convert.type.0f9 = struct_value () [symbolic]
+// CHECK:STDOUT:   %ImplicitAs.impl_witness.c75: <witness> = impl_witness imports.%ImplicitAs.impl_witness_table.a2f, @impl.4f9(%int_32) [concrete]
+// CHECK:STDOUT:   %Convert.type.035: type = fn_type @Convert.2, @impl.4f9(%int_32) [concrete]
+// CHECK:STDOUT:   %Convert.956: %Convert.type.035 = struct_value () [concrete]
+// CHECK:STDOUT:   %ImplicitAs.facet: %ImplicitAs.type.205 = facet_value Core.IntLiteral, (%ImplicitAs.impl_witness.c75) [concrete]
+// CHECK:STDOUT:   %.9c3: type = fn_type_with_self_type %Convert.type.1b6, %ImplicitAs.facet [concrete]
+// CHECK:STDOUT:   %Convert.bound: <bound method> = bound_method %int_42.20e, %Convert.956 [concrete]
+// CHECK:STDOUT:   %Convert.specific_fn: <specific function> = specific_function %Convert.956, @Convert.2(%int_32) [concrete]
+// CHECK:STDOUT:   %bound_method: <bound method> = bound_method %int_42.20e, %Convert.specific_fn [concrete]
+// CHECK:STDOUT:   %int_42.c68: %i32 = int_value 42 [concrete]
+// CHECK:STDOUT:   %ptr.235: type = ptr_type %i32 [concrete]
+// CHECK:STDOUT:   %pattern_type.fe8: type = pattern_type %ptr.235 [concrete]
+// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
+// CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.2 [concrete]
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T, 0 [symbolic]
+// CHECK:STDOUT:   %Op.type.bc9: type = fn_type @Op.3, @impl.49c(%T) [symbolic]
+// CHECK:STDOUT:   %Op.46f: %Op.type.bc9 = struct_value () [symbolic]
+// CHECK:STDOUT:   %Destroy.impl_witness.711: <witness> = impl_witness imports.%Destroy.impl_witness_table, @impl.49c(%ptr.235) [concrete]
+// CHECK:STDOUT:   %Op.type.ba2: type = fn_type @Op.3, @impl.49c(%ptr.235) [concrete]
+// CHECK:STDOUT:   %Op.649: %Op.type.ba2 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.5d5: type = ptr_type %ptr.235 [concrete]
+// CHECK:STDOUT:   %Destroy.facet.2bf: %Destroy.type = facet_value %ptr.235, (%Destroy.impl_witness.711) [concrete]
+// CHECK:STDOUT:   %.a79: type = fn_type_with_self_type %Op.type.bae, %Destroy.facet.2bf [concrete]
+// CHECK:STDOUT:   %Op.specific_fn.829: <specific function> = specific_function %Op.649, @Op.3(%ptr.235) [concrete]
+// CHECK:STDOUT:   %Destroy.impl_witness.64e: <witness> = impl_witness imports.%Destroy.impl_witness_table, @impl.49c(%i32) [concrete]
+// CHECK:STDOUT:   %Op.type.a17: type = fn_type @Op.3, @impl.49c(%i32) [concrete]
+// CHECK:STDOUT:   %Op.e6a: %Op.type.a17 = struct_value () [concrete]
+// CHECK:STDOUT:   %Destroy.facet.5f7: %Destroy.type = facet_value %i32, (%Destroy.impl_witness.64e) [concrete]
+// CHECK:STDOUT:   %.ab7: type = fn_type_with_self_type %Op.type.bae, %Destroy.facet.5f7 [concrete]
+// CHECK:STDOUT:   %Op.specific_fn.014: <specific function> = specific_function %Op.e6a, @Op.3(%i32) [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .foo = @F.%i32.1
+// CHECK:STDOUT:     .bar = @F.%i32.2
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Core.import_ref.a5b: @impl.4f9.%Convert.type (%Convert.type.0f9) = import_ref Core//prelude/parts/int, loc16_39, loaded [symbolic = @impl.4f9.%Convert (constants.%Convert.f06)]
+// CHECK:STDOUT:   %ImplicitAs.impl_witness_table.a2f = impl_witness_table (%Core.import_ref.a5b), @impl.4f9 [concrete]
+// CHECK:STDOUT:   %Core.import_ref.0b9: @impl.49c.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.49c.%Op (constants.%Op.46f)]
+// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl.49c [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @F() {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %n.patt: %pattern_type.7ce = binding_pattern n [concrete]
+// CHECK:STDOUT:     %n.var_patt: %pattern_type.7ce = var_pattern %n.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %n.var: ref %i32 = var %n.var_patt
+// CHECK:STDOUT:   %int_42: Core.IntLiteral = int_value 42 [concrete = constants.%int_42.20e]
+// CHECK:STDOUT:   %impl.elem0.loc8_3.1: %.9c3 = impl_witness_access constants.%ImplicitAs.impl_witness.c75, element0 [concrete = constants.%Convert.956]
+// CHECK:STDOUT:   %bound_method.loc8_3.1: <bound method> = bound_method %int_42, %impl.elem0.loc8_3.1 [concrete = constants.%Convert.bound]
+// CHECK:STDOUT:   %specific_fn.loc8_3.1: <specific function> = specific_function %impl.elem0.loc8_3.1, @Convert.2(constants.%int_32) [concrete = constants.%Convert.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc8_3.2: <bound method> = bound_method %int_42, %specific_fn.loc8_3.1 [concrete = constants.%bound_method]
+// CHECK:STDOUT:   %int.convert_checked: init %i32 = call %bound_method.loc8_3.2(%int_42) [concrete = constants.%int_42.c68]
+// CHECK:STDOUT:   %.loc8_3: init %i32 = converted %int_42, %int.convert_checked [concrete = constants.%int_42.c68]
+// CHECK:STDOUT:   assign %n.var, %.loc8_3
+// CHECK:STDOUT:   %.loc8_13: type = splice_block %foo.ref [concrete = constants.%i32] {
+// CHECK:STDOUT:     %Cpp.ref.loc8: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:     %foo.ref: type = name_ref foo, %i32.1 [concrete = constants.%i32]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %n: ref %i32 = bind_name n, %n.var
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %p.patt: %pattern_type.fe8 = binding_pattern p [concrete]
+// CHECK:STDOUT:     %p.var_patt: %pattern_type.fe8 = var_pattern %p.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %p.var: ref %ptr.235 = var %p.var_patt
+// CHECK:STDOUT:   %n.ref: ref %i32 = name_ref n, %n
+// CHECK:STDOUT:   %addr.loc10_21: %ptr.235 = addr_of %n.ref
+// CHECK:STDOUT:   assign %p.var, %addr.loc10_21
+// CHECK:STDOUT:   %.loc10: type = splice_block %ptr [concrete = constants.%ptr.235] {
+// CHECK:STDOUT:     %Cpp.ref.loc10: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     <elided>
+// CHECK:STDOUT:     %bar.ref: type = name_ref bar, %i32.2 [concrete = constants.%i32]
+// CHECK:STDOUT:     %ptr: type = ptr_type %bar.ref [concrete = constants.%ptr.235]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %p: ref %ptr.235 = bind_name p, %p.var
+// CHECK:STDOUT:   %impl.elem0.loc10: %.a79 = impl_witness_access constants.%Destroy.impl_witness.711, element0 [concrete = constants.%Op.649]
+// CHECK:STDOUT:   %bound_method.loc10_3.1: <bound method> = bound_method %p.var, %impl.elem0.loc10
+// CHECK:STDOUT:   %specific_fn.loc10: <specific function> = specific_function %impl.elem0.loc10, @Op.3(constants.%ptr.235) [concrete = constants.%Op.specific_fn.829]
+// CHECK:STDOUT:   %bound_method.loc10_3.2: <bound method> = bound_method %p.var, %specific_fn.loc10
+// CHECK:STDOUT:   %addr.loc10_3: %ptr.5d5 = addr_of %p.var
+// CHECK:STDOUT:   %no_op.loc10: init %empty_tuple.type = call %bound_method.loc10_3.2(%addr.loc10_3)
+// CHECK:STDOUT:   %impl.elem0.loc8_3.2: %.ab7 = impl_witness_access constants.%Destroy.impl_witness.64e, element0 [concrete = constants.%Op.e6a]
+// CHECK:STDOUT:   %bound_method.loc8_3.3: <bound method> = bound_method %n.var, %impl.elem0.loc8_3.2
+// CHECK:STDOUT:   %specific_fn.loc8_3.2: <specific function> = specific_function %impl.elem0.loc8_3.2, @Op.3(constants.%i32) [concrete = constants.%Op.specific_fn.014]
+// CHECK:STDOUT:   %bound_method.loc8_3.4: <bound method> = bound_method %n.var, %specific_fn.loc8_3.2
+// CHECK:STDOUT:   %addr.loc8: %ptr.235 = addr_of %n.var
+// CHECK:STDOUT:   %no_op.loc8: init %empty_tuple.type = call %bound_method.loc8_3.4(%addr.loc8)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: --- use_class_typedef.carbon
+// CHECK:STDOUT:
+// CHECK:STDOUT: constants {
+// CHECK:STDOUT:   %C: type = class_type @C [concrete]
+// CHECK:STDOUT:   %empty_tuple.type: type = tuple_type () [concrete]
+// CHECK:STDOUT:   %ptr.d9e: type = ptr_type %C [concrete]
+// CHECK:STDOUT:   %pattern_type.a31: type = pattern_type %ptr.d9e [concrete]
+// CHECK:STDOUT:   %Destroy.type: type = facet_type <@Destroy> [concrete]
+// CHECK:STDOUT:   %Op.type.bae: type = fn_type @Op.1 [concrete]
+// CHECK:STDOUT:   %T: type = bind_symbolic_name T, 0 [symbolic]
+// CHECK:STDOUT:   %Op.type.bc9: type = fn_type @Op.2, @impl(%T) [symbolic]
+// CHECK:STDOUT:   %Op.46f: %Op.type.bc9 = struct_value () [symbolic]
+// CHECK:STDOUT:   %Destroy.impl_witness.5a8: <witness> = impl_witness imports.%Destroy.impl_witness_table, @impl(%ptr.d9e) [concrete]
+// CHECK:STDOUT:   %Op.type.cb8: type = fn_type @Op.2, @impl(%ptr.d9e) [concrete]
+// CHECK:STDOUT:   %Op.8e3: %Op.type.cb8 = struct_value () [concrete]
+// CHECK:STDOUT:   %ptr.01d: type = ptr_type %ptr.d9e [concrete]
+// CHECK:STDOUT:   %Destroy.facet: %Destroy.type = facet_value %ptr.d9e, (%Destroy.impl_witness.5a8) [concrete]
+// CHECK:STDOUT:   %.8d5: type = fn_type_with_self_type %Op.type.bae, %Destroy.facet [concrete]
+// CHECK:STDOUT:   %Op.specific_fn: <specific function> = specific_function %Op.8e3, @Op.2(%ptr.d9e) [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: imports {
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
+// CHECK:STDOUT:     .C = %C.decl
+// CHECK:STDOUT:     .D = %C.decl
+// CHECK:STDOUT:     import Cpp//...
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %C.decl: type = class_decl @C [concrete = constants.%C] {} {}
+// CHECK:STDOUT:   %Core.import_ref.0b9: @impl.%Op.type (%Op.type.bc9) = import_ref Core//prelude/parts/destroy, loc8_29, loaded [symbolic = @impl.%Op (constants.%Op.46f)]
+// CHECK:STDOUT:   %Destroy.impl_witness_table = impl_witness_table (%Core.import_ref.0b9), @impl [concrete]
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
+// CHECK:STDOUT: fn @H(%c.param: %C, %d.param: %C) {
+// CHECK:STDOUT: !entry:
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %pd.patt: %pattern_type.a31 = binding_pattern pd [concrete]
+// CHECK:STDOUT:     %pd.var_patt: %pattern_type.a31 = var_pattern %pd.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %pd.var: ref %ptr.d9e = var %pd.var_patt
+// CHECK:STDOUT:   %c.ref: ref %C = name_ref c, %c
+// CHECK:STDOUT:   %addr.loc9_20: %ptr.d9e = addr_of %c.ref
+// CHECK:STDOUT:   assign %pd.var, %addr.loc9_20
+// CHECK:STDOUT:   %.loc9: type = splice_block %ptr.loc9 [concrete = constants.%ptr.d9e] {
+// CHECK:STDOUT:     %Cpp.ref.loc9: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %D.ref.loc9: type = name_ref D, imports.%C.decl [concrete = constants.%C]
+// CHECK:STDOUT:     %ptr.loc9: type = ptr_type %D.ref.loc9 [concrete = constants.%ptr.d9e]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %pd: ref %ptr.d9e = bind_name pd, %pd.var
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %pc.patt: %pattern_type.a31 = binding_pattern pc [concrete]
+// CHECK:STDOUT:     %pc.var_patt: %pattern_type.a31 = var_pattern %pc.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %pc.var: ref %ptr.d9e = var %pc.var_patt
+// CHECK:STDOUT:   %d.ref: ref %C = name_ref d, %d
+// CHECK:STDOUT:   %addr.loc10_20: %ptr.d9e = addr_of %d.ref
+// CHECK:STDOUT:   assign %pc.var, %addr.loc10_20
+// CHECK:STDOUT:   %.loc10: type = splice_block %ptr.loc10 [concrete = constants.%ptr.d9e] {
+// CHECK:STDOUT:     %Cpp.ref.loc10: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
+// CHECK:STDOUT:     %C.ref.loc10: type = name_ref C, imports.%C.decl [concrete = constants.%C]
+// CHECK:STDOUT:     %ptr.loc10: type = ptr_type %C.ref.loc10 [concrete = constants.%ptr.d9e]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %pc: ref %ptr.d9e = bind_name pc, %pc.var
+// CHECK:STDOUT:   %impl.elem0.loc10: %.8d5 = impl_witness_access constants.%Destroy.impl_witness.5a8, element0 [concrete = constants.%Op.8e3]
+// CHECK:STDOUT:   %bound_method.loc10_3.1: <bound method> = bound_method %pc.var, %impl.elem0.loc10
+// CHECK:STDOUT:   %specific_fn.loc10: <specific function> = specific_function %impl.elem0.loc10, @Op.2(constants.%ptr.d9e) [concrete = constants.%Op.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc10_3.2: <bound method> = bound_method %pc.var, %specific_fn.loc10
+// CHECK:STDOUT:   %addr.loc10_3: %ptr.01d = addr_of %pc.var
+// CHECK:STDOUT:   %no_op.loc10: init %empty_tuple.type = call %bound_method.loc10_3.2(%addr.loc10_3)
+// CHECK:STDOUT:   %impl.elem0.loc9: %.8d5 = impl_witness_access constants.%Destroy.impl_witness.5a8, element0 [concrete = constants.%Op.8e3]
+// CHECK:STDOUT:   %bound_method.loc9_3.1: <bound method> = bound_method %pd.var, %impl.elem0.loc9
+// CHECK:STDOUT:   %specific_fn.loc9: <specific function> = specific_function %impl.elem0.loc9, @Op.2(constants.%ptr.d9e) [concrete = constants.%Op.specific_fn]
+// CHECK:STDOUT:   %bound_method.loc9_3.2: <bound method> = bound_method %pd.var, %specific_fn.loc9
+// CHECK:STDOUT:   %addr.loc9_3: %ptr.01d = addr_of %pd.var
+// CHECK:STDOUT:   %no_op.loc9: init %empty_tuple.type = call %bound_method.loc9_3.2(%addr.loc9_3)
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT: }
+// CHECK:STDOUT:
diff --git a/toolchain/check/testdata/interop/cpp/unsupported_decl_type.carbon b/toolchain/check/testdata/interop/cpp/unsupported_decl_type.carbon
index 0b2c69e2b422..d569fa87ba7d 100644
--- a/toolchain/check/testdata/interop/cpp/unsupported_decl_type.carbon
+++ b/toolchain/check/testdata/interop/cpp/unsupported_decl_type.carbon
@@ -2,7 +2,7 @@
 // Exceptions. See /LICENSE for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
-// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/none.carbon
+// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/destroy.carbon
 //
 // AUTOUPDATE
 // TIP: To test this file alone, run:
@@ -10,49 +10,44 @@
 // TIP: To dump output, run:
 // TIP:   bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/interop/cpp/unsupported_decl_type.carbon
 
-// --- unsupported_decl.h
+// --- template.h
 
-typedef int foo;
+template<typename T> class C {};
 
-// --- fail_todo_import_unsupported_decl.carbon
+// --- fail_todo_use_template.carbon
 
 library "[[@TEST_NAME]]";
 
-import Cpp library "unsupported_decl.h";
+import Cpp library "template.h";
 
 fn F() {
   //@dump-sem-ir-begin
-  // CHECK:STDERR: fail_todo_import_unsupported_decl.carbon:[[@LINE+11]]:3: error: semantics TODO: `Unsupported: Declaration type Typedef` [SemanticsTodo]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR: fail_todo_import_unsupported_decl.carbon:[[@LINE+8]]:3: note: in `Cpp` name lookup for `foo` [InCppNameLookup]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
+  // CHECK:STDERR: fail_todo_use_template.carbon:[[@LINE+4]]:10: error: name `C` not found [NameNotFound]
+  // CHECK:STDERR:   var c: C({});
+  // CHECK:STDERR:          ^
   // CHECK:STDERR:
-  // CHECK:STDERR: fail_todo_import_unsupported_decl.carbon:[[@LINE+4]]:3: error: member name `foo` not found in `Cpp` [MemberNameNotFoundInInstScope]
-  // CHECK:STDERR:   Cpp.foo();
-  // CHECK:STDERR:   ^~~~~~~
-  // CHECK:STDERR:
-  Cpp.foo();
+  var c: C({});
   //@dump-sem-ir-end
 }
 
-// CHECK:STDOUT: --- fail_todo_import_unsupported_decl.carbon
+// CHECK:STDOUT: --- fail_todo_use_template.carbon
 // CHECK:STDOUT:
 // CHECK:STDOUT: constants {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .foo = <poisoned>
-// CHECK:STDOUT:     import Cpp//...
-// CHECK:STDOUT:   }
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: fn @F() {
 // CHECK:STDOUT: !entry:
-// CHECK:STDOUT:   %Cpp.ref: <namespace> = name_ref Cpp, imports.%Cpp [concrete = imports.%Cpp]
-// CHECK:STDOUT:   %foo.ref: <error> = name_ref foo, <error> [concrete = <error>]
+// CHECK:STDOUT:   name_binding_decl {
+// CHECK:STDOUT:     %c.patt: <error> = binding_pattern c [concrete]
+// CHECK:STDOUT:     %c.var_patt: <error> = var_pattern %c.patt [concrete]
+// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %c.var: ref <error> = var %c.var_patt [concrete = <error>]
+// CHECK:STDOUT:   <elided>
+// CHECK:STDOUT:   %c: <error> = bind_name c, <error> [concrete = <error>]
+// CHECK:STDOUT:   %impl.elem0: <error> = impl_witness_access <error>, element0 [concrete = <error>]
 // CHECK:STDOUT:   <elided>
 // CHECK:STDOUT: }
 // CHECK:STDOUT: