Robert Elz wrote:
From: Paul Eggert<eggert@cs.ucla.edu> Date: Fri, 26 Jan 2018 07:39:30 -0800 Subject: Re: [tz] OpenJDK/CLDR/ICU/Joda issues with Ireland change
| Unfortunately tm_gmtoff is not standardized by C or POSIX, perhaps | because standardizers mistakenly thought that strftime %z was enough.
No, it would have been because tm_gmtoff isn't available everywhere (and most particularly, wasn't available on the main reference system from which most of POSIX was copied.)
strftime %z wasn't available on the main reference system either, nor was it universally supported, and yet it was added to the C standard. Since tm_gmtoff and tm_zone are supported by GNU/Linux and by the BSDs, they're pretty much everywhere but in traditional APIs such as AIX and Solaris. The main objecting to adding them there, as I understand it, is that it requires changing the size of 'struct tm' and that this is more of hassle than adding a conversion spec to strftime. Unfortunately strftime "%z" doesn't suffice to determine the full UT offset. I used to be a regular contributor to POSIX standardization but dropped out due to lack of time. If there is a way I could contribute in the timestamp area (but not get deluged by other topics) I'd could resume.