Timezone bug with GMT?

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A discussion is underway regarding a potential timezone bug in Discourse when using GMT. j127 has encountered an issue where using Etc/GMT-7 results in the wrong time, despite Los Angeles being GMT-7.

The correct time is only achieved by entering Etc/GMT+7, which seems counterintuitive. j127 suggests that America/Los_Angeles and GMT-7 should be equivalent.

j127 further proposes that omitting the Etc/ prefix and making GMT -7 equivalent to America/Los_Angeles would improve user clarity. However, Stephen points out that the offset can vary due to daylight saving time (DST) changes, which occur at different times in different countries.

j127 acknowledges the DST changes but emphasizes the potential for user confusion when selecting timezones. The issue was previously discussed in another thread, as noted by JammyDodger.

1

I’m not sure whether this is a bug or I’m misunderstanding the behavior.

Example 1

Code:

[date=2022-05-06 time=01:00:00 timezone="America/Los_Angeles"]

(Los Angeles is GMT-7.)

Result:

2022-05-06T08:00:00Z

Example 2

Code:

[date=2022-05-06 time=01:00:00 timezone="Etc/GMT-7"]

Result:

Los Angeles is GMT-7. If we say, “The event is at 1pm in the timezone GMT-7” (Los Angeles timezone), and someone uses GMT-7 in Discourse like this:

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it results in the wrong time:

2022-05-05T18:00:00Z

To get Los Angeles time there (GMT-7), you have to enter GMT+7 like this:

[date=2022-05-06 time=01:00:00 timezone="Etc/GMT+7"]

Result:

2022-05-06T08:00:00Z

Shouldn’t America/Los_Angeles+7 be the same as GMT, and GMT-7 be the same as America/Los_Angeles? The widget also says 1pm in GMT-7 is different from LA:

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image400×620 31.1 KB

2

I think this has cropped up before:

3

Thanks, I searched before I posted but didn’t see that discussion.

I think it would be clearer for users if it were shown without the Etc/ prefix, and GMT-7 were the same as America/Los_Angeles, but I guess that would cause surprises for people who are already doing something with the dates programmatically.

4

I think it’s quite easy to overlook that Los_Angeles and GMT-7 aren’t the same thing.

LA is in either PDT (GMT-7) or PST (GMT-8) depending on the time of year, and the clock changes occur in different countries at different times (UK: last Sunday in March and last Sunday in October, vs US second Sunday in March and first Sunday in November) so the offset will vary.

That’s why date/time systems usually show both the time zone and the offset.

5

Thanks, we’re aware of the clock changes, but people who do find GMT-7 (or GMT-8 at another time of the year) in the timezone picker might not realize that the dates they entered aren’t what they intended. Or when they see something like this, it won’t make sense, because LA is GMT-7 at the moment: