Limit our MSVC compat hack for nested names from dependent bases

Previously, any undeclared unqualified id starting a nested name
specifier in a dependent context would have its lookup retried during
template instantiation.  Now we limit that retry hack to methods of a
class with dependent bases.  Free function templates in particular are
no longer affected by this hack.

Also, diagnose this as a Microsoft extension. This has the downside that
template authors may see this warning *and* an error during
instantiation time about this identifier. Fixing that will probably
require formalizing some kind of "delayed" identifier, instead of our
ad-hoc solutions of forming dependent AST nodes when lookup fails.

Based on a patch by Kim Gräsman!

Differential Revision: http://reviews.llvm.org/D4854

llvm-svn: 215683

1 files changed, 12 insertions, 2 deletions

diff --git a/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp b/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
index 40f73c0d9e6..4bdb97bbbd1 100644
--- a/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
+++ b/clang/test/SemaTemplate/ms-lookup-template-base-classes.cpp
@@ -220,7 +220,8 @@ template <typename T> struct C : T {
   int    *bar() { return &b; }     // expected-error {{no member named 'b' in 'PR16014::C<PR16014::A>'}} expected-warning {{lookup into dependent bases}}
   int     baz() { return T::b; }   // expected-error {{no member named 'b' in 'PR16014::A'}}
   int T::*qux() { return &T::b; }  // expected-error {{no member named 'b' in 'PR16014::A'}}
-  int T::*fuz() { return &U::a; }  // expected-error {{use of undeclared identifier 'U'}}
+  int T::*fuz() { return &U::a; }  // expected-error {{use of undeclared identifier 'U'}} \
+  // expected-warning {{unqualified lookup into dependent bases of class template 'C'}}
 };
 
 template struct B<A>;
@@ -249,7 +250,8 @@ struct A : T {
     ::UndefClass::undef(); // expected-error {{no member named 'UndefClass' in the global namespace}}
   }
   void baz() {
-    B::qux(); // expected-error {{use of undeclared identifier 'B'}}
+    B::qux(); // expected-error {{use of undeclared identifier 'B'}} \
+    // expected-warning {{unqualified lookup into dependent bases of class template 'A'}}
   }
 };
 
@@ -460,3 +462,11 @@ template <typename T> struct D : C<T> {
   int x = f<NameFromBase>();
 };
 }
+
+namespace function_template_undef_impl {
+template<class T>
+void f() {
+  Undef::staticMethod(); // expected-error {{use of undeclared identifier 'Undef'}}
+  UndefVar.method(); // expected-error {{use of undeclared identifier 'UndefVar'}}
+}
+}