Re: Cygwin strptime() is missing "%s" which strftime() has

[Craig Howland <howland@LGSInnovations.com>]

On 07/25/2017 12:47 PM, Brian Inglis wrote:
> Don't we need to save and zero errno to distinguish a new error, and restore if
> it stays zero, rather than just pick up the current value, and assume if it
> is/was ERANGE it's bad?
      Yes, it needs to be set to 0 before calling strtol_l.
      POSIX does not define any errors for strptime().  Therefore by general 
rule it is permitted for it to set errno to be non-0. However, it is just as 
easy to always restore it instead of checking for non-0 (why add the check?).  
Always restoring also indirectly conveys the intent that strptime() is not 
required to set errno, that no errors are defined for it.

On 07/25/2017 05:19 AM, Corinna Vinschen wrote:
>> Neither %F nor %s are defined for strptime() in POSIX, so they should not be
>> expected to be portable.  (See
>> http://pubs.opengroup.org/onlinepubs/9699919799/functions/strptime.html) For
>> that matter, %s is not defined for strftime(), either in POSIX or C99, even
>> though it is in Newlib.  If either of these are added, they should have
>> gates (or at the very least, comments) to show they are extensions.  (They
>> appear to be GLIBC extensions, based on comments in the man page from a
>> GLIBC-based system.)
> Right, in theory.  Just a bit late in the game I guess.  We already
> support %u, %V, %Z unconditionally.  I checked the FreeBSD code and
> they don't even bother to add comments ¯\_(ツ)_/¯
Not having done it right earlier is not a good reason to not do it better going 
forward.  That said, OK, no compile-time gate since the other things are 
hard-coded, but let's at least have comments that they are extensions:

+	    case 'F' :		/* %Y-%m-%d (GNU extension) */
+	    case 's' : {	/* (GNU extension) */


Craig