Treat special names inside Cpp as not existing

carbon-language · Mar 3, 2025 · 16867c9 · 16867c9
1 parent 4cf320d
commit 16867c9
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Showing 3 changed files with 12 additions and 19 deletions.
diff --git a/toolchain/check/import_cpp.cpp b/toolchain/check/import_cpp.cpp
@@ -150,8 +150,15 @@ auto ImportCppFiles(Context& context, llvm::StringRef importing_file_path,
 // Look ups the given name in the Clang AST. Returns the lookup result if lookup
 // was successful.
 static auto ClangLookup(Context& context, SemIR::LocId loc_id,
-                        llvm::StringRef name)
+                        SemIR::NameId name_id)
     -> std::optional<clang::LookupResult> {
+  std::optional<llvm::StringRef> name =
+      context.names().GetAsStringIfIdentifier(name_id);
+  if (!name) {
+    // Special names never exist in C++ code.
+    return std::nullopt;
+  }
+
   clang::ASTUnit* ast = context.sem_ir().cpp_ast();
   CARBON_CHECK(ast);
   clang::Sema& sema = ast->getSema();
@@ -160,7 +167,7 @@ static auto ClangLookup(Context& context, SemIR::LocId loc_id,
       sema,
       clang::DeclarationNameInfo(
           clang::DeclarationName(
-              sema.getPreprocessor().getIdentifierInfo(name)),
+              sema.getPreprocessor().getIdentifierInfo(*name)),
           clang::SourceLocation()),
       clang::Sema::LookupNameKind::LookupOrdinaryName);
 
@@ -263,18 +270,7 @@ static auto ImportNameDecl(Context& context, SemIR::LocId loc_id,
 auto ImportNameFromCpp(Context& context, SemIR::LocId loc_id,
                        SemIR::NameScopeId scope_id, SemIR::NameId name_id)
     -> SemIR::InstId {
-  std::optional<llvm::StringRef> name =
-      context.names().GetAsStringIfIdentifier(name_id);
-  if (!name) {
-    // Special names never exist in C++ code.
-    CARBON_DIAGNOSTIC(CppNonIdentifierName, Error,
-                      "Using non-identifier name `{0}` in `Cpp`",
-                      SemIR::NameId);
-    context.emitter().Emit(loc_id, CppNonIdentifierName, name_id);
-    return SemIR::ErrorInst::SingletonInstId;
-  }
-
-  auto lookup = ClangLookup(context, loc_id, *name);
+  auto lookup = ClangLookup(context, loc_id, name_id);
   if (!lookup) {
     return SemIR::InstId::None;
   }

diff --git a/toolchain/check/testdata/interop/cpp/no_prelude/function_decl.carbon b/toolchain/check/testdata/interop/cpp/no_prelude/function_decl.carbon
@@ -47,7 +47,7 @@ library "[[@TEST_NAME]]";
 import Cpp library "function_special_name_decl.h";
 
 fn MyF() {
-  // CHECK:STDERR: fail_import_function_special_name_decl.carbon:[[@LINE+4]]:3: error: Using non-identifier name `base` in `Cpp` [CppNonIdentifierName]
+  // CHECK:STDERR: fail_import_function_special_name_decl.carbon:[[@LINE+4]]:3: error: member name `base` not found in `Cpp` [MemberNameNotFoundInScope]
   // CHECK:STDERR:   Cpp.base();
   // CHECK:STDERR:   ^~~~~~~~
   // CHECK:STDERR:
@@ -275,9 +275,7 @@ fn F() {
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: imports {
-// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {
-// CHECK:STDOUT:     .base = <error>
-// CHECK:STDOUT:   }
+// CHECK:STDOUT:   %Cpp: <namespace> = namespace file.%Cpp.import_cpp, [concrete] {}
 // CHECK:STDOUT: }
 // CHECK:STDOUT:
 // CHECK:STDOUT: file {

diff --git a/toolchain/diagnostics/diagnostic_kind.def b/toolchain/diagnostics/diagnostic_kind.def
@@ -316,7 +316,6 @@ CARBON_DIAGNOSTIC_KIND(QualifiedDeclInIncompleteClassScope)
 CARBON_DIAGNOSTIC_KIND(QualifiedDeclInUndefinedInterfaceScope)
 
 // Name lookup.
-CARBON_DIAGNOSTIC_KIND(CppNonIdentifierName)
 CARBON_DIAGNOSTIC_KIND(FromExtendHere)
 CARBON_DIAGNOSTIC_KIND(InCppNameLookup)
 CARBON_DIAGNOSTIC_KIND(InNameLookup)