Re: BUG #19095: Test if function exit() is used fail when linked static

Hi Hackers,

This is a refreshed version of the patch to unify the exit() reference check
performed during libpq builds. Earlier versions had duplicated logic between
the Makefile and Meson builds, while platform-specific details were also split
between comments and build rules.

Following feedback from Michael, Daniel, Tom, and Nazir, v4 includes the
following changes:

Changes in v4

• Added top-level AC_PATH_PROG(NM, nm) in configure.ac, and propagated
  it via NM, so both build systems use the same nm path.

• Updated Makefile and Meson rules to invoke the new Perl helper using

• - -nm=$(NM) / - -nm=@NM@

• Centralized all platform-specific behavior in the Perl script:

  • Skip on Solaris and Windows

  • Handle ThreadSanitizer (__tsan_func_exit)

  • Handle OpenBSD’s __cxa_atexit

  • Whitelist pthread_exit()

  • Gracefully skip if nm is not available

• Removed redundant checks from meson.build and Makefile and replaced them with
  a short reference to the script.

• Added missing cleanup (closing filehandle), and improved comments.

• Ensured consistent behavior across autoconf and Meson builds.

Testing:

Both autoconf and Meson builds were tested with:

• Valid nm present

• Missing nm

• Solaris/Windows-skip behavior

• Injected exit() symbol to confirm failure mode works correctly

The behavior is now uniform across build systems.

Patch is attached.

Thanks for the reviews so far, and I welcome further comments.

Regards,
Vasuki