Don't get confused if a extern "C" builtin function is redeclared without
the extern "C".

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171260 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 92b1e4a..2d34e4c 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -2440,7 +2440,7 @@
     return Builtin::BIstrlen;
 
   default:
-    if (isExternC()) {
+    if (hasCLanguageLinkage()) {
       if (FnInfo->isStr("memset"))
         return Builtin::BImemset;
       else if (FnInfo->isStr("memcpy"))
diff --git a/test/SemaCXX/warn-bad-memaccess.cpp b/test/SemaCXX/warn-bad-memaccess.cpp
index 3a02c84..7a7459a 100644
--- a/test/SemaCXX/warn-bad-memaccess.cpp
+++ b/test/SemaCXX/warn-bad-memaccess.cpp
@@ -5,6 +5,11 @@
 extern "C" void *memcpy(void *s1, const void *s2, unsigned n);
 extern "C" void *memcmp(void *s1, const void *s2, unsigned n);
 
+
+// Redeclare without the extern "C" to test that we still figure out that this
+// is the "real" memset.
+void *memset(void *, int, unsigned);
+
 // Several types that should not warn.
 struct S1 {} s1;
 struct S2 { int x; } s2;