From 865dd8c8fe65d7743cfbc412316e59e6c149624d Mon Sep 17 00:00:00 2001
From: Argyrios Kyrtzidis <akyrtzi@gmail.com>
Date: Mon, 25 Apr 2011 21:39:50 +0000
Subject: [PATCH] 'extern' variables in functions don't shadow externs in
 global scope. Fixes rdar://8883302, this time for C++ as well.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@130157 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaDecl.cpp        | 18 ++++--------------
 test/SemaCXX/warn-shadow.cpp | 11 +++++++++++
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index d07bd4b72d..200f8ce037 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -3664,10 +3664,11 @@ void Sema::CheckShadow(Scope *S, VarDecl *D, const LookupResult& R) {
     return;
 
   // Don't diagnose declarations at file scope.
-  DeclContext *NewDC = D->getDeclContext();
-  if (NewDC->isFileContext())
+  if (D->hasGlobalStorage())
     return;
-  
+
+  DeclContext *NewDC = D->getDeclContext();
+
   // Only diagnose if we're shadowing an unambiguous field or variable.
   if (R.getResultKind() != LookupResult::Found)
     return;
@@ -3684,17 +3685,6 @@ void Sema::CheckShadow(Scope *S, VarDecl *D, const LookupResult& R) {
 
   if (VarDecl *shadowedVar = dyn_cast<VarDecl>(ShadowedDecl))
     if (shadowedVar->isExternC()) {
-      // Don't warn for this case:
-      //
-      // @code
-      // extern int bob;
-      // void f() {
-      //   extern int bob;
-      // }
-      // @endcode
-      if (D->isExternC())
-        return;
-
       // For shadowing external vars, make sure that we point to the global
       // declaration, not a locally scoped extern declaration.
       for (VarDecl::redecl_iterator
diff --git a/test/SemaCXX/warn-shadow.cpp b/test/SemaCXX/warn-shadow.cpp
index 3bf9af414d..68e9467a93 100644
--- a/test/SemaCXX/warn-shadow.cpp
+++ b/test/SemaCXX/warn-shadow.cpp
@@ -70,3 +70,14 @@ struct S {
   }
 };
 }
+
+extern int bob; // expected-note {{previous declaration is here}}
+
+// rdar://8883302
+void rdar8883302() {
+  extern int bob; // don't warn for shadowing.
+}
+
+void test8() {
+  int bob; // expected-warning {{declaration shadows a variable in the global namespace}}
+}
-- 
2.50.1