--- a/clang/lib/Parse/ParseAST.cpp	Wed Jul 21 10:27:27 2021 +0900
+++ b/clang/lib/Parse/ParseAST.cpp	Wed Nov 09 17:45:10 2022 +0900
@@ -154,8 +154,12 @@
     llvm::TimeTraceScope TimeScope("Frontend");
     P.Initialize();
     Parser::DeclGroupPtrTy ADecl;
-    for (bool AtEOF = P.ParseFirstTopLevelDecl(ADecl); !AtEOF;
-         AtEOF = P.ParseTopLevelDecl(ADecl)) {
+    Sema::ModuleImportState ImportState;
+    EnterExpressionEvaluationContext PotentiallyEvaluated(
+        S, Sema::ExpressionEvaluationContext::PotentiallyEvaluated);
+
+    for (bool AtEOF = P.ParseFirstTopLevelDecl(ADecl, ImportState); !AtEOF;
+         AtEOF = P.ParseTopLevelDecl(ADecl, ImportState)) {
       // If we got a null return and something *was* parsed, ignore it.  This
       // is due to a top-level semicolon, an action override, or a parse error
       // skipping something.
@@ -168,6 +172,27 @@
   for (Decl *D : S.WeakTopLevelDecls())
     Consumer->HandleTopLevelDecl(DeclGroupRef(D));
 
+  // For C++20 modules, the codegen for module initializers needs to be altered
+  // and to be able to use a name based on the module name.
+
+  // At this point, we should know if we are building a non-header C++20 module.
+  if (S.getLangOpts().CPlusPlusModules) {
+    // If we are building the module from source, then the top level module
+    // will be here.
+    Module *CodegenModule = S.getCurrentModule();
+    bool Interface = true;
+    if (CodegenModule)
+      // We only use module initializers for importable module (including
+      // partition implementation units).
+      Interface = S.currentModuleIsInterface();
+    else if (S.getLangOpts().isCompilingModuleInterface())
+      // If we are building the module from a PCM file, then the module can be
+      // found here.
+      CodegenModule = S.getPreprocessor().getCurrentModule();
+
+    if (Interface && CodegenModule)
+      S.getASTContext().setModuleForCodeGen(CodegenModule);
+  }
   Consumer->HandleTranslationUnit(S.getASTContext());
 
   // Finalize the template instantiation observer chain.