Parse: Don't crash when 'typename' shows up in an attribute

isDeclarationSpecifier performs error recovers which jostles the token
stream.  Specifically, TryAnnotateTypeOrScopeToken will end up consuming
a typename token which will confuse the attribute parsing machinery as
we no-longer have something identifier-like.

llvm-svn: 224903

clang/lib/Parse/ParseDecl.cpp

@@ -143,7 +143,8 @@ void Parser::ParseGNUAttributes(ParsedAttributes &attrs,
         continue;
 
       // Expect an identifier or declaration specifier (const, int, etc.)
-      if (Tok.isNot(tok::identifier) && !isDeclarationSpecifier())
+      if (Tok.isNot(tok::identifier) && !isTypeQualifier() &&
+          !isKnownToBeTypeSpecifier(Tok))
         break;
 
       IdentifierInfo *AttrName = Tok.getIdentifierInfo();

clang/test/Parser/cxx-attributes.cpp

@@ -20,3 +20,5 @@ namespace PR17666 {
   typedef int __attribute__((aligned(int(1)))) T1;
   typedef int __attribute__((aligned(int))) T2; // expected-error {{expected '(' for function-style cast}}
 }
+
+__attribute((typename)) int x; // expected-error {{expected ')'}}

clang/test/Parser/namespace-alias-attr.cpp

@@ -4,5 +4,5 @@ namespace A
 {
 }
 
-namespace B __attribute__ (( static )) = A; // expected-error{{attributes cannot be specified on namespace alias}}
+namespace B __attribute__ (( const )) = A; // expected-error{{attributes cannot be specified on namespace alias}}