mirror of https://git.tukaani.org/xz.git
55bf3f49a8
It's more robust in case the compiler allows pre-C99 implicit function
declarations. If an x86 intrinsic is missing and gets treated as
implicit function, the linking step will very probably fail. This
isn't the only way to workaround implicit function declarations but
it might be the simplest and cleanest.
The problem hasn't been observed in the wild.
There are a couple more AC_COMPILE_IFELSE uses in configure.ac.
Of these, Landlock check calls prctl() and in theory could have
the same problem. In practice it doesn't as the check program
looks for several other things too. However, it was changed to
AC_LINK_IFELSE still to look more correct.
Similarly, m4/tuklib_cpucores.m4 and m4/tuklib_physmem.m4 were
updated although they haven't given any trouble either. They
have worked all these years because those check programs rely
on specific headers and types: if headers or types are missing,
compilation will fail. Using the linker makes these checks more
similar to the ones in cmake/tuklib_*.cmake which always link.
(cherry picked from commit
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| .. | ||
| .gitignore | ||
| ax_pthread.m4 | ||
| getopt.m4 | ||
| posix-shell.m4 | ||
| tuklib_common.m4 | ||
| tuklib_cpucores.m4 | ||
| tuklib_integer.m4 | ||
| tuklib_mbstr.m4 | ||
| tuklib_physmem.m4 | ||
| tuklib_progname.m4 | ||
| visibility.m4 | ||