OS.get_time_zone_info() does not adjust bias during DST

[Beefster09]

Godot version: 3.2

OS/device including version: Windows 10

Issue description: When calling OS.get_time_zone_info() during part of the year when DST is active, the bias field returned does not take daylight saving time into account, so for instance, Mountain Daylight Time reads as a bias of 420 (7 hours) instead of 360 (6 hours). A bias of 420 would be correct for the standard time part of the year, but is incorrect when DST is active.

Steps to reproduce: Call OS.get_time_zone_info(), print the result to console, and observe the incorrect bias.

Minimal reproduction project: Any project will do.

[Calinou]

It seems to be taken into account on Linux. I live in France (which is GMT+1), and I get the following on Linux: {bias:120, name:CEST}

This is probably OS-specific. Further testing on macOS, mobile and HTML5 is welcome.

Minimal reproduction project: test_date_bias.zip

[michasng]

I'm on windows 10 in germany. Should be getting a bias of 120 as well right now, but I get this:
{bias:60, name:Mitteleuropäische Sommerzeit}
(Also note that CEST has been automatically translated for me.)

Exporting to the web results in this:
{bias:120, name:GMT}
Now GMT is wrong, but the bias is correct.

[jamie-pate]

Workaround on windows:

# Get time zone info with a bug fix for windows time zone issues.
func get_time_zone_info_fixed() -> Dictionary:
	var result = OS.get_time_zone_info()
	if OS.get_name() == "Windows":
		var output = []
                # NOTE: probably want to cache this result as it can open a cmd.exe popup every time you call it in windows :(
		OS.execute('WMIC.exe', ["OS","Get","CurrentTimeZone"],true, output)
		var bias = int(output[0].split("\n")[1])
		result.bias = bias
	return result

[bati22]

I tried to reproduce the bug, but failed. Maybe it's because it's winter time.

Godot version:
Godot 3.2.3.stable

OS/device including version:
Ubuntu 20.04.1 LTS

[jamie-pate]

@bati22 afaik it only affects windows, and may only happen during Daylight Savings. You could set your computer clock to the summer to test.