From c3691827c04df000d153854361ac3405e43850e8 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Tue, 13 Jan 2015 09:55:56 +0000
Subject: [PATCH] Sema: An extern declaration can't be a redeclaration of a
 parameter

In the following:
void f(int x) { extern int x; }

The second declaration of 'x' shouldn't be considered a redeclaration of
the parameter.

llvm-svn: 225780
---
 clang/lib/Sema/SemaDecl.cpp      | 6 ++----
 clang/test/Sema/private-extern.c | 4 ++++
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index baa6822da71e..82ffd4da5f87 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -3282,14 +3282,12 @@ void Sema::MergeVarDecl(VarDecl *New, LookupResult &Previous) {
   }
 
   // Check if extern is followed by non-extern and vice-versa.
-  if (New->hasExternalStorage() &&
-      !Old->hasLinkage() && Old->isLocalVarDecl()) {
+  if (New->hasGlobalStorage() && !Old->hasLinkage() && Old->hasLocalStorage()) {
     Diag(New->getLocation(), diag::err_extern_non_extern) << New->getDeclName();
     Diag(OldLocation, PrevDiag);
     return New->setInvalidDecl();
   }
-  if (Old->hasLinkage() && New->isLocalVarDecl() &&
-      !New->hasExternalStorage()) {
+  if (Old->hasGlobalStorage() && !New->hasLinkage() && New->hasLocalStorage()) {
     Diag(New->getLocation(), diag::err_non_extern_extern) << New->getDeclName();
     Diag(OldLocation, PrevDiag);
     return New->setInvalidDecl();
diff --git a/clang/test/Sema/private-extern.c b/clang/test/Sema/private-extern.c
index 0c13c92bba77..94afd87fbb87 100644
--- a/clang/test/Sema/private-extern.c
+++ b/clang/test/Sema/private-extern.c
@@ -83,3 +83,7 @@ __private_extern__ int g19;
 int g19 = 0;
 
 __private_extern__ int g20 = 0;
+
+void f10(int g20) { // expected-note{{previous definition is here}}
+  extern int g20; // expected-error{{extern declaration of 'g20' follows non-extern declaration}}
+}