According to the C11 Standard (7.27.2.5), there is a function timespec_get
specified in time.h
. I have tried several compilers, including clang and several versions of gcc, which are supposed to support C11, but this function is always missing. The macro TIME_UTC
is also missing.
Here is a test file mytime.c
:
#include <time.h>
#include <stdio.h>
int main() {
printf("C version: %ld\n", __STDC_VERSION__);
fflush(stdout);
struct timespec ts;
timespec_get(&ts, TIME_UTC);
}
and the output using Clang:
$ cc --version
Apple LLVM version 8.0.0 (clang-800.0.42.1)
Target: x86_64-apple-darwin15.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
$ cc -std=c11 mytime.c
mytime.c:9:3: warning: implicit declaration of function 'timespec_get' is invalid in C99
[-Wimplicit-function-declaration]
timespec_get(&ts, TIME_UTC);
^
mytime.c:9:21: error: use of undeclared identifier 'TIME_UTC'
timespec_get(&ts, TIME_UTC);
^
1 warning and 1 error generated.
I commented out the timespec_get
line just to make sure I am using C11, and I am.
I get basically the same results for gcc versions 4.8, 5, and 6.
I am using a Mac, OS 10.11.6.
The Mac OS X standard library does not conform to any modern version of C or POSIX. It is stuck at C99 and POSIX 2001 and has conformance problems even with respect to these.