Fixes a corner case bug whereby declaring and defining an extern variable in a

particular sequence causes its definition to not be generated in the object file.
(fixes radar 8071804).

llvm-svn: 106424

1 files changed, 9 insertions, 1 deletions

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 25687e15c4c..c912af878a8 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -701,7 +701,15 @@ VarDecl::DefinitionKind VarDecl::isThisDeclarationADefinition() const {
   // AST for 'extern "C" int foo;' is annotated with 'extern'.
   if (hasExternalStorage())
     return DeclarationOnly;
-
+  
+  if (getStorageClassAsWritten() == Extern ||
+       getStorageClassAsWritten() == PrivateExtern) {
+    for (const VarDecl *PrevVar = getPreviousDeclaration();
+         PrevVar; PrevVar = PrevVar->getPreviousDeclaration()) {
+      if (PrevVar->getLinkage() == InternalLinkage && PrevVar->hasInit())
+        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