Fixes a code gen. bug by removing an assert.

It is ok to have c++-ness inside extern "C" 
block. Fixes pr6644.

llvm-svn: 101948

clang/lib/CodeGen/Mangle.cpp

@@ -306,8 +306,6 @@ static bool isStd(const NamespaceDecl *NS) {
 
 static const DeclContext *IgnoreLinkageSpecDecls(const DeclContext *DC) {
   while (isa<LinkageSpecDecl>(DC)) {
-    assert(cast<LinkageSpecDecl>(DC)->getLanguage() ==
-           LinkageSpecDecl::lang_cxx && "Unexpected linkage decl!");
     DC = DC->getParent();
   }
 

clang/test/CodeGenCXX/c-linkage.cpp

@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -emit-llvm -o - %s | FileCheck %s
+// pr6644
+
+extern "C" {
+  namespace N {
+    struct X { 
+      virtual void f();
+    };
+    void X::f() { }
+  }
+}
+
+// CHECK: define void @_ZN1N1X1fEv