time lib is missing timegm

[marcelstoer]

time.h is declaring gmtime (struct from time_t) but the inverse function is missing. timegm is like mktime but for UTC rather than local time.

While I could take existing implementations (-> here or here) ideally it'd be part of the platform.

[earlephilhower]

From http://man7.org/linux/man-pages/man3/timegm.3.html :

CONFORMING TO:
These functions are nonstandard GNU extensions that are also present
on the BSDs. Avoid their use.

@devyte , are you sure we want to start including things like this? We don't use glibc, which is for heavy-duty OSes, we use newlib which is more-or-less POSIX only.

[devyte]

Um, I missed that "Avoid their use" note in the man page when . A quick look online shows the same: the functions aren't standard and their usual implementations aren't portable, hence shouldn't be used. This link shows a supposedly portable implementation, but the recommendation is still to avoid their use.
Closing.