Incorrect condition for st_mtim field name

[michaelforney]

I noticed an issue with the ifdefs in d2bf82f (nanosecond mtime fields). That commit seems to be misinterpreting how feature test macros work[0]. _POSIX_C_SOURCE, _XOPEN_SOURCE, _BSD_SOURCE and _SVID_SOURCE are defined by the application to tell the libc headers what to expose. They are not defined by the libc as the commit message says.

The POSIX standardized field name is st_mtim[1], so that should be used as the default and worked around only for platforms that don't have this field (i.e. macOS and apparently AIX). This will prevent having to extend the condition for every platform that uses the POSIX name (i.e. Solaris in 1952afa, and FreeBSD in febd3b3). This also breaks on musl, and I suspect BSDs as well.

[0] https://ftp.gnu.org/old-gnu/Manuals/glibc-2.2.3/html_node/libc_13.html
[1] http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_stat.h.html

[markand]

Hello,

Is there any chance that the fix gets merged? It looks like Alpine also use this patch.

[jhasse]

Yes, someone needs to check if this doesn't break anything for AIX, Android, and Solaris and comment on #1513. In general I would prefer if we could test more of this with CI, see #1526.