Don't mark 'extern "C" void f(void)' as having extern storage class.

Instead, we check for one line extern "C" context in linkage computation and
when deciding if a variable is a definition.

This hopefully completes the transition to having "as written" semantics for
hasExternalStorage.

llvm-svn: 180258

1 files changed, 10 insertions, 7 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 4a3e8781dee..cb375eb4e26 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1572,17 +1572,20 @@ VarDecl::DefinitionKind VarDecl::isThisDeclarationADefinition(
   //   initializer, the declaration is an external definition for the identifier
   if (hasInit())
     return Definition;
-  // AST for 'extern "C" int foo;' is annotated with 'extern'.
+
   if (hasExternalStorage())
     return DeclarationOnly;
 
-  if (hasExternalStorage()) {
-    for (const VarDecl *PrevVar = getPreviousDecl();
-         PrevVar; PrevVar = PrevVar->getPreviousDecl()) {
-      if (PrevVar->getLinkage() == InternalLinkage)
-        return DeclarationOnly;
-    }
+  // [dcl.link] p7:
+  //   A declaration directly contained in a linkage-specification is treated
+  //   as if it contains the extern specifier for the purpose of determining
+  //   the linkage of the declared name and whether it is a definition.
+  const DeclContext *DC = getDeclContext();
+  if (const LinkageSpecDecl *SD = dyn_cast<LinkageSpecDecl>(DC)) {
+    if (SD->getLanguage() == LinkageSpecDecl::lang_c && !SD->hasBraces())
+      return DeclarationOnly;
   }
+
   // C99 6.9.2p2:
   //   A declaration of an object that has file scope without an initializer,
   //   and without a storage class specifier or the scs 'static', constitutes