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

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@215683 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 2 deletions

diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index a70aca2ad8..b1b8b5d1dc 100644
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -703,8 +703,13 @@ bool Sema::BuildCXXNestedNameSpecifier(Scope *S,
   if (getLangOpts().MSVCCompat) {
     DeclContext *DC = LookupCtx ? LookupCtx : CurContext;
     if (DC->isDependentContext() && DC->isFunctionOrMethod()) {
-      SS.Extend(Context, &Identifier, IdentifierLoc, CCLoc);
-      return false;
+      CXXRecordDecl *ContainingClass = dyn_cast<CXXRecordDecl>(DC->getParent());
+      if (ContainingClass && ContainingClass->hasAnyDependentBases()) {
+        Diag(IdentifierLoc, diag::ext_undeclared_unqual_id_with_dependent_base)
+            << &Identifier << ContainingClass;
+        SS.Extend(Context, &Identifier, IdentifierLoc, CCLoc);
+        return false;
+      }
     }
   }