PR20991: ::decltype is not valid.

llvm-svn: 219043
diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index 8f22f56..47fdd82 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -242,7 +242,8 @@
     *MayBePseudoDestructor = false;
   }
 
-  if (Tok.is(tok::kw_decltype) || Tok.is(tok::annot_decltype)) {
+  if (!HasScopeSpecifier &&
+      (Tok.is(tok::kw_decltype) || Tok.is(tok::annot_decltype))) {
     DeclSpec DS(AttrFactory);
     SourceLocation DeclLoc = Tok.getLocation();
     SourceLocation EndLoc  = ParseDecltypeSpecifier(DS);