2 files changed, 42 insertions, 9 deletions

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 2658e96..558ee3f 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -16146,6 +16146,20 @@ Decl *Sema::ActOnStartLinkageSpecification(Scope *S, SourceLocation ExternLoc,
   LinkageSpecDecl *D = LinkageSpecDecl::Create(Context, CurContext, ExternLoc,
                                                LangStr->getExprLoc(), Language,
                                                LBraceLoc.isValid());
+
+  /// C++ [module.unit]p7.2.3
+  /// - Otherwise, if the declaration
+  ///   - ...
+  ///   - ...
+  ///   - appears within a linkage-specification,
+  ///   it is attached to the global module.
+  if (getLangOpts().CPlusPlusModules) {
+    Module *GlobalModule =
+        PushGlobalModuleFragment(ExternLoc, /*IsImplicit=*/true);
+    D->setModuleOwnershipKind(Decl::ModuleOwnershipKind::ModulePrivate);
+    D->setLocalOwningModule(GlobalModule);
+  }
+
   CurContext->addDecl(D);
   PushDeclContext(S, D);
   return D;
@@ -16162,6 +16176,10 @@ Decl *Sema::ActOnFinishLinkageSpecification(Scope *S,
     LinkageSpecDecl* LSDecl = cast<LinkageSpecDecl>(LinkageSpec);
     LSDecl->setRBraceLoc(RBraceLoc);
   }
+
+  if (getLangOpts().CPlusPlusModules)
+    PopGlobalModuleFragment();
+
   PopDeclContext();
   return LinkageSpec;
 }
diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index af95b1a..34a6c6e 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -68,15 +68,8 @@ Sema::ActOnGlobalModuleFragmentDecl(SourceLocation ModuleLoc) {
 
   // We start in the global module; all those declarations are implicitly
   // module-private (though they do not have module linkage).
-  auto &Map = PP.getHeaderSearchInfo().getModuleMap();
-  auto *GlobalModule = Map.createGlobalModuleFragmentForModuleUnit(ModuleLoc);
-  assert(GlobalModule && "module creation should not fail");
-
-  // Enter the scope of the global module.
-  ModuleScopes.push_back({});
-  ModuleScopes.back().BeginLoc = ModuleLoc;
-  ModuleScopes.back().Module = GlobalModule;
-  VisibleModules.setVisible(GlobalModule, ModuleLoc);
+  Module *GlobalModule =
+      PushGlobalModuleFragment(ModuleLoc, /*IsImplicit=*/false);
 
   // All declarations created from now on are owned by the global module.
   auto *TU = Context.getTranslationUnitDecl();
@@ -708,3 +701,25 @@ Decl *Sema::ActOnFinishExportDecl(Scope *S, Decl *D, SourceLocation RBraceLoc) {
 
   return D;
 }
+
+Module *Sema::PushGlobalModuleFragment(SourceLocation BeginLoc,
+                                       bool IsImplicit) {
+  ModuleMap &Map = PP.getHeaderSearchInfo().getModuleMap();
+  Module *GlobalModule =
+      Map.createGlobalModuleFragmentForModuleUnit(BeginLoc, getCurrentModule());
+  assert(GlobalModule && "module creation should not fail");
+
+  // Enter the scope of the global module.
+  ModuleScopes.push_back({BeginLoc, GlobalModule,
+                          /*ModuleInterface=*/false,
+                          /*ImplicitGlobalModuleFragment=*/IsImplicit});
+  VisibleModules.setVisible(GlobalModule, BeginLoc);
+
+  return GlobalModule;
+}
+
+void Sema::PopGlobalModuleFragment() {
+  assert(!ModuleScopes.empty() && getCurrentModule()->isGlobalModule() &&
+         "left the wrong module scope, which is not global module fragment");
+  ModuleScopes.pop_back();
+}