FreeBSD 15 buildbot: Python fails to build with error: call to undeclared function 'ppoll'

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Bug report

Bug description:

FreeBSD 15 buildbot: https://buildbot.python.org/#/builders/1238/builds/7690

Build error:

--- Modules/selectmodule.o ---
./Modules/selectmodule.c:703:23: error: call to undeclared function 'ppoll'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration]
  703 |         poll_result = ppoll(self->ufds, self->ufd_len, ts_p, NULL);
      |                       ^
./Modules/selectmodule.c:703:23: note: did you mean 'poll'?
/usr/include/poll.h:117:5: note: 'poll' declared here
  117 | int     poll(struct pollfd _pfd[], nfds_t _nfds, int _timeout);
      |         ^
1 error generated.

configure:

checking for ppoll... yes
...
checking for sys/poll.h... yes

Python has been modified to use the ppoll() function by PR gh-143529.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Other

Linked PRs

• gh-144309: Build Python with POSIX 2024 #144310

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FreeBSD 14 buildbot just works: https://buildbot.python.org/#/builders/1232/builds/7867

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@opsec: Would you mind to have a look at your buildbot worker (FreeBSD 15)?

The manual page says that ppoll() is part of the C library and requires #include <poll.h>: https://man.freebsd.org/cgi/man.cgi?ppoll(2) Modules/selectmodule.c already includes poll.h if the HAVE_POLL_H macro is defined, which should be the case on the FreeBSD 15 buildbot (configure says checking for sys/poll.h... yes).

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Oh, /usr/include/poll.h only defines ppoll() if __POSIX_VISIBLE is 202405 or greater.

#if __POSIX_VISIBLE >= 202405
int	ppoll(struct pollfd _pfd[], nfds_t _nfds,
	    const struct timespec *__restrict _timeout,
	    const sigset_t *__restrict _newsigmask);
#endif

[opsec]

that buildbot worker is a bit behind. I'll work to update the worker.

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I upgraded my FreeBSD 14 VM to FreeBSD 15 but the upgrade crashed FreeBSD with https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=289769 bug :-( I reinstalled a fresh FreeBSD 15.

I'm working on a fix.

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I wrote #144310 to build Python with POSIX 2024. It should fix the ppoll() issue.