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Re: Build failure with GCC 15 (defaults to -std=gnu23)

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Sam James <sam@gentoo.org>, pgsql-bugs@lists.postgresql.org
Date: 2024-11-17T22:45:24Z
Lists: pgsql-bugs 
On Mon, Nov 18, 2024 at 10:49 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Yeah.  Well, what say we leave the "typedef unsigned char bool"
> pathway in place, but set things up to use that only if sizeof
> the stdbool type isn't 1 --- and then it's up to any hypothetical
> users of that pathway to choose a compiler and compiler options
> that won't choke on it.

It sounds like we should stop using the old and broken
AC_CHECK_HEADER_STDBOOL macro.  I think it was doing two jobs in old
times: there were some systems that shipped a defective/pre-standard
stdbool.h, and some systems without it.  I think both classes of
system are gone from the universe.  Later autoconf versions check for
C99 "or later", but we're stuck with the old one and I doubt we are
going to upgrade it.  Found in their NEWS:

*** AC_HEADER_STDBOOL, AC_CHECK_HEADER_STDBOOL are obsolescent and less picky.
These macros are now obsolescent, as programs can simply include
stdbool.h unconditionally. If you use these macros, they now accept
a stdbool.h that exists but does nothing, so long as ‘bool’, ‘true’,
and ‘false’ work anyway. This is for compatibility with C 2023 and
with C++.

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Require sizeof(bool) == 1.

  2. If a C23 compiler is detected, try asking for C17.

  3. Fix C23 compiler warning

  4. Rename C23 keyword

  5. Assume that <stdbool.h> conforms to the C standard.

  6. Revise tree-walk APIs to improve spec compliance & silence warnings.