> I haven't checked, but I believe most implementations just print the
> zone name from the current timezone, using tm_isdst to decide whether
> to print the standard or daylight version of the name. This is
> insufficient with zoneinfo for zones where the name changed over time,
> where it would print the wrong name for historical times. So instead
> we support printing any one of the zone names from the current zone,

> if the tm_zone member points to one of them, and blank otherwise.

You are right. I was under the impression that glibc uses tm_zone, but double checking the implementation right now, it doesn't. So the behavioral discrepancy here comes from the fact that musl checks tm_zone at all, not the other way around. Sorry for looking in the completely wrong direction here.