[Bug middle-end/117633] New: system.h still does a define bool to unsigned char even for C23

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117633

            Bug ID: 117633
           Summary: system.h still does a define bool to unsigned char
                    even for C23
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Keywords: internal-improvement
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

GCC's system.h currently does:
```
/* Provide a fake boolean type.  We make no attempt to use the
   C99 _Bool, as it may not be available in the bootstrap compiler,
   and even if it is, it is liable to be buggy.
   This must be after all inclusion of system headers, as some of
   them will mess us up.  */

#undef TRUE
#undef FALSE

#ifdef __cplusplus
  /* Obsolete.  */
# define TRUE true
# define FALSE false
#else /* !__cplusplus */
# undef bool
# undef true
# undef false

# define bool unsigned char
# define true 1
# define false 0

  /* Obsolete.  */
# define TRUE true
# define FALSE false
#endif /* !__cplusplus */

```


Though I am not sure if system.h is ever included in C programs any more. But
maybe we should fix this to use C23's bool if we are compiling for C23 ...