[clang] [ObjC] Stop hard-coding the list of keywords that are allowed in selectors (PR #138952)

[Akira Hatanaka via cfe-commits]

https://github.com/ahatanak created https://github.com/llvm/llvm-project/pull/138952

The design intent is that ObjC selector pieces can be arbitrary keywords, including basic C keywords like `if`, and the grammar permits this and makes it unambiguous.

Use TokenKinds.def to autogenerate the list of allowed keywords instead.

rdar://150383689

>From 8ce8105255835400d00787580db50b15039be97b Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanak at gmail.com>
Date: Wed, 7 May 2025 13:02:06 -0700
Subject: [PATCH] [ObjC] Stop hard-coding the list of keywords that are allowed
 in selectors

The design intent is that ObjC selector pieces can be arbitrary
keywords, including basic C keywords like `if`, and the grammar permits
this and makes it unambiguous.

Use TokenKinds.def to autogenerate the list of allowed keywords instead.

rdar://150383689
---
 clang/lib/Parse/ParseObjc.cpp                 | 71 +------------------
 clang/test/SemaObjCXX/cxxoperator-selector.mm |  5 ++
 2 files changed, 7 insertions(+), 69 deletions(-)

diff --git a/clang/lib/Parse/ParseObjc.cpp b/clang/lib/Parse/ParseObjc.cpp
index 6496b4fba54f2..a427cb24e48bb 100644
--- a/clang/lib/Parse/ParseObjc.cpp
+++ b/clang/lib/Parse/ParseObjc.cpp
@@ -1095,75 +1095,8 @@ IdentifierInfo *Parser::ParseObjCSelectorPiece(SourceLocation &SelectorLoc) {
   }
 
   case tok::identifier:
-  case tok::kw_asm:
-  case tok::kw_auto:
-  case tok::kw_bool:
-  case tok::kw_break:
-  case tok::kw_case:
-  case tok::kw_catch:
-  case tok::kw_char:
-  case tok::kw_class:
-  case tok::kw_const:
-  case tok::kw_const_cast:
-  case tok::kw_continue:
-  case tok::kw_default:
-  case tok::kw_delete:
-  case tok::kw_do:
-  case tok::kw_double:
-  case tok::kw_dynamic_cast:
-  case tok::kw_else:
-  case tok::kw_enum:
-  case tok::kw_explicit:
-  case tok::kw_export:
-  case tok::kw_extern:
-  case tok::kw_false:
-  case tok::kw_float:
-  case tok::kw_for:
-  case tok::kw_friend:
-  case tok::kw_goto:
-  case tok::kw_if:
-  case tok::kw_inline:
-  case tok::kw_int:
-  case tok::kw_long:
-  case tok::kw_mutable:
-  case tok::kw_namespace:
-  case tok::kw_new:
-  case tok::kw_operator:
-  case tok::kw_private:
-  case tok::kw_protected:
-  case tok::kw_public:
-  case tok::kw_register:
-  case tok::kw_reinterpret_cast:
-  case tok::kw_restrict:
-  case tok::kw_return:
-  case tok::kw_short:
-  case tok::kw_signed:
-  case tok::kw_sizeof:
-  case tok::kw_static:
-  case tok::kw_static_cast:
-  case tok::kw_struct:
-  case tok::kw_switch:
-  case tok::kw_template:
-  case tok::kw_this:
-  case tok::kw_throw:
-  case tok::kw_true:
-  case tok::kw_try:
-  case tok::kw_typedef:
-  case tok::kw_typeid:
-  case tok::kw_typename:
-  case tok::kw_typeof:
-  case tok::kw_union:
-  case tok::kw_unsigned:
-  case tok::kw_using:
-  case tok::kw_virtual:
-  case tok::kw_void:
-  case tok::kw_volatile:
-  case tok::kw_wchar_t:
-  case tok::kw_while:
-  case tok::kw__Bool:
-  case tok::kw__Complex:
-  case tok::kw___alignof:
-  case tok::kw___auto_type:
+#define KEYWORD(X,Y) case tok::kw_ ## X:
+#include "clang/Basic/TokenKinds.def"
     IdentifierInfo *II = Tok.getIdentifierInfo();
     SelectorLoc = ConsumeToken();
     return II;
diff --git a/clang/test/SemaObjCXX/cxxoperator-selector.mm b/clang/test/SemaObjCXX/cxxoperator-selector.mm
index 8134b82ebacbb..2348bd783f519 100644
--- a/clang/test/SemaObjCXX/cxxoperator-selector.mm
+++ b/clang/test/SemaObjCXX/cxxoperator-selector.mm
@@ -19,5 +19,10 @@ - (id) and{return 0; };
 - (id) xor{return 0; };
 - (id) or{return 0; };
 
+- (void)decltype {}
+- (void)constexpr {}
+- (void)noexcept {}
+- (void)nullptr {}
+
 - (void)dataSetForValuesBetween:(NSDate *)startDate and:(NSDate *)endDate { return; }
 @end