time.h (GNU Gnulib)

Gnulib module: time-h

Portability problems fixed by Gnulib:

‘struct timespec’ is not defined on some platforms.
The macro TIME_UTC is not defined on many platforms: glibc 2.15, macOS 10.13, FreeBSD 11.0, NetBSD 7.1, OpenBSD 6.0, Minix 3.1.8, AIX 7.1, HP-UX 11.31, IRIX 6.5, Solaris 11.3, Cygwin 2.9, mingw, MSVC 14, Android 9.0.
Some platforms provide a NULL macro that cannot be used in arbitrary expressions: NetBSD 5.0.

Portability problems fixed by the Gnulib module year2038:

On some platforms where time_t defaults to 32-bit but can be changed to 64-bit, functions like stat can fail with errno == EOVERFLOW when a 32-bit timestamp is out of range, such as with a file timestamp in the far future or past: glibc 2.34+ atop 32-bit x86 or ARM Linux. See Avoiding the year 2038 problem.

Portability problems not fixed by Gnulib:

On platforms where time_t is always 32-bit, functions like stat can fail with errno == EOVERFLOW when a timestamp is out of range, such as with a file timestamp in the far future or past; on other such platforms, the functions silently return the low-order 32 bits of the correct timestamp. These platforms will be obsolete when 32-bit time_t rolls around, which will occur in 2038 for the typical case when time_t is signed. See Avoiding the year 2038 problem.
On some platforms the tv_nsec member of struct timespec is not of type long, but is of type long long instead: glibc x32