AST: Fix the linkage of static vars in fn template specializations

We that static variables in function template specializations were
externally visible.  The manglers assumed that externally visible static
variables were numbered in Sema.  We would end up mangling static
variables in the same specialization with the same mangling number which
would give all of them the same name.

This fixes PR21904.

llvm-svn: 224316

clang/lib/AST/Decl.cpp

@@ -1192,7 +1192,7 @@ static LinkageInfo getLVForLocalDecl(const NamedDecl *D,
   } else {
     const FunctionDecl *FD = cast<FunctionDecl>(OuterD);
     if (!FD->isInlined() &&
-        FD->getTemplateSpecializationKind() == TSK_Undeclared)
+        !isTemplateInstantiation(FD->getTemplateSpecializationKind()))
       return LinkageInfo::none();
 
     LV = getLVForDecl(FD, computation);

clang/test/CodeGenCXX/function-template-specialization.cpp

@@ -1,4 +1,8 @@
 // RUN: %clang_cc1 -emit-llvm -triple %itanium_abi_triple %s -o - | FileCheck %s
+
+// CHECK-DAG: _ZZN7PR219047GetDataIiEERKibE1i = internal global i32 4
+// CHECK-DAG: _ZZN7PR219047GetDataIiEERKibE1i_0 = internal global i32 2
+
 template<typename T, typename U>
 T* next(T* ptr, const U& diff);
 
@@ -24,3 +28,18 @@ void test2(int *iptr, double *dptr, int diff) {
   // CHECK: _Z4nextIdiEPT_S1_RKT0_
   dptr = next(dptr, diff);
 }
+
+namespace PR21904 {
+template <typename>
+const int &GetData(bool);
+
+template <>
+const int &GetData<int>(bool b) {
+  static int i = 4;
+  if (b) {
+    static int i = 2;
+    return i;
+  }
+  return i;
+}
+}