Hi!
On Wed, Aug 13, 2025 at 03:29:24PM +0200, Jakub Jelinek wrote:
> My r16-3059 PR120778 change which introduced the -Wkeyword-macro option
> and made it a default for C++26 -pedantic broke quite a few tests on
> powerpc*. The problem is that the backend predefines bool and _Bool as
> macros
The AltiVec PIM required this (or one of a few other options that get
bool defined).
> (unclear why _Bool for C++ because in C++ _Bool is not a keyword)
Dunno. What does git history say?
Hrm, you added it yourself, in 58195b740ddf :-) It has something to do
with PR40017.
"I'd say handling _Bool the same way as bool after vector would be a
good idea."
:-)
> to make it a NODE_CONDITIONAL macro, so for e.g. -std=c++26 -pedantic-errors
> we diagnose it on every TU as an error.
> C++26 says that
The AltiVec PIM was published in 1999. Quite a bit earlier :-)
> PR target/121520
> * config/rs6000/rs6000-c.cc (rs6000_cpu_cpp_builtins): Temporarily
> clear NODE_WARN flag on "bool" or "_Bool" around builtin_define
> of those keywords if warn_keyword_macro.
>
> --- gcc/config/rs6000/rs6000-c.cc.jj 2025-04-08 14:08:49.819301801 +0200
> +++ gcc/config/rs6000/rs6000-c.cc 2025-08-13 09:00:07.115878529 +0200
> @@ -636,8 +636,30 @@ rs6000_cpu_cpp_builtins (cpp_reader *pfi
> {
> builtin_define ("vector=vector");
> builtin_define ("pixel=pixel");
> - builtin_define ("bool=bool");
> - builtin_define ("_Bool=_Bool");
> + if (warn_keyword_macro)
> + {
> + cpp_lookup (parse_in,
> + (const unsigned char *) "bool",
> + sizeof ("bool") - 1)->flags &= ~NODE_WARN;
> + builtin_define ("bool=bool");
> + cpp_lookup (parse_in,
> + (const unsigned char *) "bool",
> + sizeof ("bool") - 1)->flags |= NODE_WARN;
> + }
> + else
> + builtin_define ("bool=bool");
Hrm. Is there no more obvious way to do this?
If you really want to bit-twiddle things here, can't you at least use
sizeof ("bool") - 1)->flags ^= NODE_WARN;
twice? It works correctly way more often (what you have does not always
restore the original!)
And a comment would help, of course.
Why put this inside an "if" anyway, can't you disable the warning even
if it won't ever fire anyway?
> + if (warn_keyword_macro && !c_dialect_cxx ())
The warn_ flag at least seems superfluous. You might want a comment
that this is what this is for though :-)
Segher
