Recover from missing typenames on template args for MSVC compatibility

While matching a non-type template argument against a known template
type parameter we now modify the AST's TemplateArgumentLoc to assume the
user wrote typename.  Under -fms-compatibility, we downgrade our
diagnostic from an error to an extwarn.

Reviewed by: rsmith

Differential Revision: http://reviews.llvm.org/D4049

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@210607 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 47bcc817e4..d2ba82bc16 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -2181,6 +2181,17 @@ Sema::BuildQualifiedDeclarationNameExpr(CXXScopeSpec &SS,
     return ExprError();
   }
 
+  if (R.isSingleResult() && R.getAsSingle<TypeDecl>()) {
+    // Diagnose a missing typename if this resolved unambiguously to a type in a
+    // dependent context.
+    // FIXME: Issue a fixit and recover as though the user had written
+    // 'typename'.
+    Diag(SS.getBeginLoc(), diag::err_typename_missing)
+        << SS.getScopeRep() << NameInfo.getName().getAsString()
+        << SourceRange(SS.getBeginLoc(), NameInfo.getEndLoc());
+    return ExprError();
+  }
+
   // Defend against this resolving to an implicit member access. We usually
   // won't get here if this might be a legitimate a class member (we end up in
   // BuildMemberReferenceExpr instead), but this can be valid if we're forming