time: EEST timezone not recognized on windows

[mohammedrefaat]

What version of Go are you using (go version)?

$ go version
1.21.0

Does this issue reproduce with the latest release?

yes

What did you do?

i use this code in my software work in windows

zone, _:= time.Now().Zone()
location_currentzone, err := time.LoadLocation(zone)
if err != nil {

	return time.Now(), err
}

final := te.In(location_currentzone)

but when i upgrade go from 1.20.6 to 1.21.0
time.LoadLocation recognize only to utc and local only and didn't recognize any zone output from time.Now().Zone()
this happened in debug or build in machine have 1.21.0 golang

error:
unknown time zone EEST

[AhmedEmad92]

Same here , but it gives me error : the device is not ready

and when i downgraded to 1.20.6 , it works fine !!!

[seankhliao]

cc @golang/windows

[qmuntal]

I can reproduce the error using previous go releases, not only go1.21:

package main

import (
	"fmt"
	"os"
	"time"
)

func main() {
	loc, err := time.LoadLocation("EEST")
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	fmt.Println(loc)
}

go1.20.2 run . 
unknown time zone EEST
exit status 1

I don't know why it was working before for you @mohammedrefaat.

The EEST is coming from here, were we are mapping a Windows time zone, e.g. GTB Standard Time, into an identifier that Go can handle. The problem is that the time/tzdata database doesn't has an entry for EEST. Maybe @ianlancetaylor or @bcmills will know why.

[ianlancetaylor]

Go just uses the tzdata timezone database (https://github.com/eggert/tz). That database doesn't define an EEST timezone. It does have EET, and it uses EEST as the summer time variant of EET, but it doesn't recognize EEST as a standalone timezone.

That said, I don't think this has much if anything to do with the WIndows abbreviation code. This code, which looks like it might correspond to the code in the original report, fails on Linux in my timezone:

package main

import (
	"fmt"
	"os"
	"time"
)

func main() {
	zone, _ := time.Now().Zone()
	fmt.Println(zone)
	loc, err := time.LoadLocation(zone)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}
	fmt.Println(loc)
}

I get

PDT
unknown time zone PDT

This shows that the timezone abbreviations returned by time.Time.Zone aren't themselves recognized as timezone names.

Closing this issue as a dup of #5909.

[mohammedrefaat]

I think you need to try it on Windows, I use this code in Windows 11 22H2 os build 22621.2213 :

package main

import (
	"fmt"
	"os"
	"time"
	_ "time/tzdata"
)

func main() {
	te := time.Now()
	zone, _ := time.Now().Zone()
	fmt.Println(zone)
	location_currentzone, err := time.LoadLocation(zone)
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	final := te.In(location_currentzone)
	fmt.Println(final)
}

in go 1.20.7
I get

EET
2023-08-17 09:59:00.4998128 +0300 EEST

in go 1.21.0
i get

EEST
unknown time zone EEST
exit status 1

i think zone in
zone, _ := time. Now().Zone()

must return time zone EET not summer time variant of EET in go 1.21.0

[ianlancetaylor]

When I run your program on my system, which is in the timezone America/Los_Angeles, I get

PDT
unknown time zone PDT

That happens with both tip and Go 1.20.

My point is that in general it doesn't work to pass the string returned by time.Time.Zone to time.LoadLocation. It does work for a few specific cases. EET is one of the cases where it happens to work. I don't know why the tzdata database works that way.

I do see that there is a difference between Go 1.20 and Go 1.21 that affects your case, but it appears to be a change in the Windows timezone information. Every so often we update to the current version of https://raw.githubusercontent.com/unicode-org/cldr/main/common/supplemental/windowsZones.xml. When we did that for the 1.21 release, it changed "Egypt Standard Time" to return EEST for summer time. In Go 1.20 it returned EET. That was a change in the Windows timezone file, not in anything that Go controls.

Hope this helps.