Subject: Re: bug#79437: 30.2; world-clock silently and incorrectly parses invalid time zone

From: Jorge P. de Morais Neto <[email-masked]>
Date: Sat, 13 Sep 2025 20:56:44 -0300

Hi.  I reply below:

Em [2025-09-13 sáb 08:05:55-0700], Paul Eggert escreveu:

> No, as we merely need to check whether the TZ setting matches a time
> zone file. (This is for the typical case where each named time zone
> has a file; Android would be different.)
>
> Yeah, probably not worth the hassle.

I am an IT infrastructure analyst and not a software developer, so I am
unsure whether to opine on the bug's solution, but what "hassle" are you
talking about?

A. Development time;
B. code complexity; or
C. runtime cost?

Anyway, I see many possible solutions and workarounds:

1. `world-clock' could check the timezone name is valid, and warn in
   case it is not.
2. custom.el could validate `zoneinfo-style-world-list' when it is set.
3. The docstring of `zoneinfo-style-world-list' and `world-clock' could
   warn the user about the problem.

I believe 3 should be implemented in any case.  Ideally it would be
combined with 1, 2, or preferably both.

Kind regards!