[ruby-core:77990] [Ruby trunk Bug#11595][Rejected] Time#utc? and Time#gmt? return misleading results based on $TZ

[akr@fsij.org]

Issue #11595 has been updated by Akira Tanaka.

Status changed from Open to Rejected

Current behavior is intentional.

Time#utc? returns the mode of Time object, not the time zone offset is zero.

The mode affects several methods.

For example, Time#to_s generates "UTC" for UTC Time objects and
numeric timezone offset string for non-UTC Time objects.
The result of Time#utc? method means the difference of them.

```
% TZ=GMT ruby -e '
u = Time.utc(2000)
l = Time.local(2000)
p [u, u.utc?]
p [l, l.utc?]'       
[2000-01-01 00:00:00 UTC, true]
[2000-01-01 00:00:00 +0000, false]
```

----------------------------------------
Bug #11595: Time#utc? and Time#gmt? return misleading results based on $TZ
https://bugs.ruby-lang.org/issues/11595#change-61327

* Author: David Celis
* Status: Rejected
* Priority: Normal
* Assignee: Akira Tanaka
* ruby -v: ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
----------------------------------------
There is an issue with Time#utc? and its alias, Time#gmt?, that return misleading results based on the value of the TZ environment variable. It seems that the only way for a Time instance to return `true` for `utc?` is if you explicitly call `#utc` on it before:

~~~
ENV['TZ'] = 'UTC'
# => "UTC"
time = Time.now
# => 2015-10-14 19:30:00 +0000
time.utc?
# => false
time = time.utc
# => 2015-10-14 19:30:00 UTC
time.utc?
# => true
~~~

This seems misleading based on the value of $TZ being "UTC". The expected result for calling `Time.now.utc?` in this case would be `true`, as would that be expected for time zones that are considered links to "UTC" based on the [tzdata list](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones). These include "UTC", "GMT", "Etc/UTC", "Etc/GMT", "Universal", etc.

---Files--------------------------------
time_utc.patch (927 Bytes)


-- 
https://bugs.ruby-lang.org/