eliminate template type constraint and add additional tests

Author: a-tarasyuk

clang/lib/Sema/SemaDeclCXX.cpp

@@ -2655,7 +2655,7 @@ CXXBaseSpecifier *Sema::CheckBaseSpecifier(CXXRecordDecl *Class,
       return nullptr;
     }
 
-    if (BaseType.hasQualifiers() && !isa<SubstTemplateTypeParmType>(BaseType)) {
+    if (BaseType.hasQualifiers()) {
       std::string Quals =
           BaseType.getQualifiers().getAsString(Context.getPrintingPolicy());
       Diag(BaseLoc, diag::warn_qual_base_type)

clang/test/SemaCXX/warn-base-type-qualifiers.cpp

@@ -1,5 +1,10 @@
 // RUN: %clang_cc1 %s -std=c++11 -Wignored-qualifiers -verify
 
+template <typename T> struct add_const {
+  using type = const T;
+};
+template <typename T> using add_const_t = typename add_const<T>::type;
+
 class A { };
 
 typedef const A A_Const;
@@ -13,8 +18,18 @@ class C : public A_Const_Volatile { }; // expected-warning {{'const volatile' qu
 struct D {
   D(int);
 };
-template <typename T> struct E : T {
+
+template <typename T> struct E : T { // expected-warning {{'const' qualifier on base class type 'const D' have no effect}} \
+                                     // expected-note {{base class 'const D' specified here}}
   using T::T;
   E(int &) : E(0) {}
 };
-E<const D> e(1);
+E<const D> e(1); // expected-note {{in instantiation of template class 'E<const D>' requested here}}
+
+template <typename T>
+struct G : add_const<T>::type { // expected-warning {{'const' qualifier on base class type 'add_const<D>::type' (aka 'const D') have no effect}} \
+                                // expected-note {{base class 'add_const<D>::type' (aka 'const D') specified here}}
+  using T::T;
+  G(int &) : G(0) {}
+};
+G<D> g(1); // expected-note {{in instantiation of template class 'G<D>' requested here}}