[Clang] Fix crash in Parser::ParseDirectDeclarator by adding check th…

…at token is not an annotation token

In Parser::ParseDirectDeclarator(...) in some cases ill-formed code can cause an
annotation token to end up where it was not expected. The fix is to add a
!Tok.isAnnotation() guard before attempting to access identifier info.

This fixes: #64836

Differential Revision: https://reviews.llvm.org/D158804

clang/docs/ReleaseNotes.rst

@@ -218,6 +218,8 @@ Bug Fixes in This Version
   (`#65156 <https://github.com/llvm/llvm-project/issues/65156>`_)
 - Clang no longer considers the loss of ``__unaligned`` qualifier from objects as
   an invalid conversion during method function overload resolution.
+- Fix parser crash when dealing with ill-formed objective C++ header code. Fixes
+  (`#64836 <https://github.com/llvm/llvm-project/issues/64836>`_)
 
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

clang/lib/Parse/ParseDecl.cpp

@@ -6667,7 +6667,7 @@ void Parser::ParseDirectDeclarator(Declarator &D) {
       // Objective-C++: Detect C++ keywords and try to prevent further errors by
       // treating these keyword as valid member names.
       if (getLangOpts().ObjC && getLangOpts().CPlusPlus &&
-          Tok.getIdentifierInfo() &&
+          !Tok.isAnnotation() && Tok.getIdentifierInfo() &&
           Tok.getIdentifierInfo()->isCPlusPlusKeyword(getLangOpts())) {
         Diag(getMissingDeclaratorIdLoc(D, Tok.getLocation()),
              diag::err_expected_member_name_or_semi_objcxx_keyword)

clang/test/Parser/gh64836.cpp

@@ -0,0 +1,12 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -xobjective-c++-header %s
+
+template <typename, typename>
+class C {};
+
+class B {
+  p // expected-error {{unknown type name 'p'}}
+ private: // expected-error {{'private' is a keyword in Objective-C++}}
+  void f() {} // expected-error {{expected '(' for function-style cast or type construction}}
+  C<int, decltype(f)> c; // expected-error {{use of undeclared identifier 'f'}}
+  // expected-error@-1 {{expected member name}}
+};