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

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Thomas Munro <thomas.munro@gmail.com>
Cc: Sam James <sam@gentoo.org>, pgsql-bugs@lists.postgresql.org
Date: 2024-11-17T20:26:41Z
Lists: pgsql-bugs 
Thomas Munro <thomas.munro@gmail.com> writes:
> On Mon, Nov 18, 2024 at 7:12 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> Having said that, I can reproduce this on gcc 14 using -std=gnu23.
>> It appears that configure is deciding that <stdbool.h> is not
>> conformant to C99 because it doesn't declare "bool" as a macro.
>> Did C23 really remove that !?

> Yes, seems to be a general pattern: features introduced as keyword
> _Xxx with a library macro xxx -> _Xxx (usually where xxx is already a
> keyword in C++ but the C committee was afraid to unleash a new keyword
> directly on the world, I guess?), and now xxx is finally graduating to
> real keyword status.  Other examples: static_assert, thread_local,
> alignas.

Fun.  Well, now that we insist on C99 support in all branches,
I wonder whether we can just remove all the non-stdbool support.
The one thing that looks tricky is that we insist on sizeof(bool)
being 1, but are there any remaining supported platforms where
it isn't?  The buildfarm doesn't have any examples.

			regards, tom lane

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.