After parsing a ':' in an enum-specifier within class context,

disambiguate between an expression (for a bit-field width) and a type
(for a fixed underlying type). Since the disambiguation can be
expensive (due to tentative parsing), we perform a simplistic
disambiguation based on one-token lookahead before going into the
full-blown tentative parsing. Based on a patch by Daniel Wallin.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@120582 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 110 insertions, 0 deletions

diff --git a/lib/Parse/ParseTentative.cpp b/lib/Parse/ParseTentative.cpp
index 9bd000c323..997d01076b 100644
--- a/lib/Parse/ParseTentative.cpp
+++ b/lib/Parse/ParseTentative.cpp
@@ -593,6 +593,116 @@ Parser::TPResult Parser::TryParseDeclarator(bool mayBeAbstract,
   return TPResult::Ambiguous();
 }
 
+Parser::TPResult 
+Parser::isExpressionOrTypeSpecifierSimple(tok::TokenKind Kind) {
+  switch (Kind) {
+  // Obviously starts an expression.
+  case tok::numeric_constant:
+  case tok::char_constant:
+  case tok::string_literal:
+  case tok::wide_string_literal:
+  case tok::l_square:
+  case tok::l_paren:
+  case tok::amp:
+  case tok::star:
+  case tok::plus:
+  case tok::plusplus:
+  case tok::minus:
+  case tok::minusminus:
+  case tok::tilde:
+  case tok::exclaim:
+  case tok::kw_sizeof:
+  case tok::kw___func__:
+  case tok::kw_const_cast:
+  case tok::kw_delete:
+  case tok::kw_dynamic_cast:
+  case tok::kw_false:
+  case tok::kw_new:
+  case tok::kw_operator:
+  case tok::kw_reinterpret_cast:
+  case tok::kw_static_cast:
+  case tok::kw_this:
+  case tok::kw_throw:
+  case tok::kw_true:
+  case tok::kw_typeid:
+  case tok::kw_alignof:
+  case tok::kw_noexcept:
+  case tok::kw_nullptr:
+  case tok::kw___null:
+  case tok::kw___alignof:
+  case tok::kw___builtin_choose_expr:
+  case tok::kw___builtin_offsetof:
+  case tok::kw___builtin_types_compatible_p:
+  case tok::kw___builtin_va_arg:
+  case tok::kw___imag:
+  case tok::kw___real:
+  case tok::kw___FUNCTION__:
+  case tok::kw___PRETTY_FUNCTION__:
+  case tok::kw___has_nothrow_assign:
+  case tok::kw___has_nothrow_copy:
+  case tok::kw___has_nothrow_constructor:
+  case tok::kw___has_trivial_assign:
+  case tok::kw___has_trivial_copy:
+  case tok::kw___has_trivial_constructor:
+  case tok::kw___has_trivial_destructor:
+  case tok::kw___has_virtual_destructor:
+  case tok::kw___is_abstract:
+  case tok::kw___is_base_of:
+  case tok::kw___is_class:
+  case tok::kw___is_empty:
+  case tok::kw___is_enum:
+  case tok::kw___is_pod:
+  case tok::kw___is_polymorphic:
+  case tok::kw___is_union:
+  case tok::kw___is_literal:
+  case tok::kw___uuidof:
+    return TPResult::True();
+      
+  // Obviously starts a type-specifier-seq:
+  case tok::kw_char:
+  case tok::kw_const:
+  case tok::kw_double:
+  case tok::kw_enum:
+  case tok::kw_float:
+  case tok::kw_int:
+  case tok::kw_long:
+  case tok::kw_restrict:
+  case tok::kw_short:
+  case tok::kw_signed:
+  case tok::kw_struct:
+  case tok::kw_union:
+  case tok::kw_unsigned:
+  case tok::kw_void:
+  case tok::kw_volatile:
+  case tok::kw__Bool:
+  case tok::kw__Complex:
+  case tok::kw_class:
+  case tok::kw_typename:
+  case tok::kw_wchar_t:
+  case tok::kw_char16_t:
+  case tok::kw_char32_t:
+  case tok::kw_decltype:
+  case tok::kw_thread_local:
+  case tok::kw__Decimal32:
+  case tok::kw__Decimal64:
+  case tok::kw__Decimal128:
+  case tok::kw___thread:
+  case tok::kw_typeof:
+  case tok::kw___cdecl:
+  case tok::kw___stdcall:
+  case tok::kw___fastcall:
+  case tok::kw___thiscall:
+  case tok::kw___vector:
+  case tok::kw___pixel:
+    return TPResult::False();
+
+  default:
+    break;
+  }
+  
+  return TPResult::Ambiguous();
+}
+
 /// isCXXDeclarationSpecifier - Returns TPResult::True() if it is a declaration
 /// specifier, TPResult::False() if it is not, TPResult::Ambiguous() if it could
 /// be either a decl-specifier or a function-style cast, and TPResult::Error()