When we enter a module within a linkage specification, switch the linkage

specification and the TU to the new module.

This is necessary to get the module ownership correct for entities that we
temporarily hang off the TranslationUnitDecl, such as template parameters and
function parameters.

llvm-svn: 303373

2 files changed, 36 insertions, 5 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index ba1e97b33d6..5e937aa6996 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -16048,8 +16048,10 @@ void Sema::ActOnModuleBegin(SourceLocation DirectiveLoc, Module *Mod) {
   // FIXME: Consider creating a child DeclContext to hold the entities
   // lexically within the module.
   if (getLangOpts().trackLocalOwningModule()) {
-    cast<Decl>(CurContext)->setHidden(true);
-    cast<Decl>(CurContext)->setLocalOwningModule(Mod);
+    for (auto *DC = CurContext; DC; DC = DC->getLexicalParent()) {
+      cast<Decl>(DC)->setHidden(true);
+      cast<Decl>(DC)->setLocalOwningModule(Mod);
+    }
   }
 }
 
@@ -16082,9 +16084,13 @@ void Sema::ActOnModuleEnd(SourceLocation EomLoc, Module *Mod) {
 
   // Any further declarations are in whatever module we returned to.
   if (getLangOpts().trackLocalOwningModule()) {
-    cast<Decl>(CurContext)->setLocalOwningModule(getCurrentModule());
-    if (!getCurrentModule())
-      cast<Decl>(CurContext)->setHidden(false);
+    // The parser guarantees that this is the same context that we entered
+    // the module within.
+    for (auto *DC = CurContext; DC; DC = DC->getLexicalParent()) {
+      cast<Decl>(DC)->setLocalOwningModule(getCurrentModule());
+      if (!getCurrentModule())
+        cast<Decl>(DC)->setHidden(false);
+    }
   }
 }
 
diff --git a/clang/test/Modules/extern_cxx.cpp b/clang/test/Modules/extern_cxx.cpp
new file mode 100644
index 00000000000..97ec726de23
--- /dev/null
+++ b/clang/test/Modules/extern_cxx.cpp
@@ -0,0 +1,25 @@
+// RUN: %clang_cc1 -x c++-module-map -fmodule-name=A -verify %s -fmodules-local-submodule-visibility
+module A { module B {} module C {} }
+
+#pragma clang module contents
+
+#pragma clang module begin A.B
+extern "C++" {
+  #pragma clang module begin A.C
+  template<typename T> void f(T t);
+  #pragma clang module end
+
+  void g() { f(0); } // ok
+}
+
+extern "C++" {
+  #pragma clang module begin A.C
+  } // expected-error {{extraneous closing brace}}
+  #pragma clang module end
+  
+  #pragma clang module begin A.C
+  extern "C++" { // expected-note {{to match this '{'}}
+  #pragma clang module end // expected-error {{expected '}' at end of module}}
+}
+
+#pragma clang module end