What is the correct way, if any, to assert whether a tz::TimeZone is UTC or equivalent to UTC?

[Yomguithereal]

I am asking because on some systems (I only succeeded in reproducing this on a Windows Github Actions VM), TimeZone::get("UTC") is not equal to TimeZone::UTC, e.g. TimeZone::get("UTC") might return a TimeZone(TZif("UTC")). I understand that TimeZone comparison is not straightforward at all (as explained by this section in the docs) and I do not object to the fact that PartialEq might return a non equality there.

But in some function I am writing, I am given a TimeZone object, and I must apply some optimized logic if the timezone is in fact UTC. So what would be a proper way to assert whether a TimeZone object is in fact UTC. Or, but I don't know whether this makes sense or is even correct, whether a TimeZone object is "equivalent" to UTC, e.g. GMT?

[BurntSushi]

I think the intent here is that getting UTC always gives you the UTC constant. Can you share an example of when that is not true?

Otherwise, if you want to know if a time zone is always a fixed offset of zero, you can use TimeZone::fixed_offset. Although a fixed offset of zero isn't necessarily equivalent in every way to UTC. (Likely only actual difference would be in localization.)

[Yomguithereal]

I don't have a dev machine on hand currently so I cannot yet provide an example of code that reproduces the issue, but I think the bundled db get function impl here does not have the same hardcoded condition regarding UTC like the one you have for both the concatenated db and the zoneinfo one?

[BurntSushi]

Yup, probably a bug.

[BurntSushi]

Filed: #346

[Yomguithereal]

Thanks for the fix @BurntSushi :). I will test using TimeZone::fixed_offset for equivalence then, thanks for the tip.