Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

time: Date not handling location as it was in previous versions of go #34923

Closed
lockwobr opened this issue Oct 15, 2019 · 2 comments
Closed

time: Date not handling location as it was in previous versions of go #34923

lockwobr opened this issue Oct 15, 2019 · 2 comments

Comments

@lockwobr
Copy link

@lockwobr lockwobr commented Oct 15, 2019

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

$ go version
go1.13 darwin/amd64

Does this issue reproduce with the latest release?

yes, seems to be in 1.13.x currently.

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/brian/Library/Caches/go-build"
GOENV="/Users/brian/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/brian/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/brian/software/knock/data-services/go.mod"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/g0/633mr_rd6bvbx4g3__1hk7tc0000gn/T/go-build973777294=/tmp/go-build -gno-record-gcc-switches -fno-common"

$ uname -a
Darwin brians-MacBook-Pro.local 18.7.0 Darwin Kernel Version 18.7.0: Tue Aug 20 16:57:14 PDT 2019; root:xnu-4903.271.2~2/RELEASE_X86_64 x86_64

osx version 10.14.6 (18G95)

What did you do?

https://play.golang.org/p/1-gK7cWKVEO

package main

import (
	"fmt"
	"time"
)

func main() {

    loc, err := time.LoadLocation("America/Los_Angeles")
    fmt.Println(err)
    expected := time.Date(0, time.January, 1, 12, 34, 56, 789000000, loc)
    
    fmt.Println(expected)
}

What did you expect to see?

1.13 you get

<nil>
0000-01-01 12:34:56.789 -0752 LMT

What did you see instead?

1.12.7 you get

<nil>
0000-01-01 12:34:56.789 -0800 PST
@ianlancetaylor ianlancetaylor changed the title time.Date not handling location as it was in previous versions of go time: Date not handling location as it was in previous versions of go Oct 15, 2019
@ianlancetaylor
Copy link
Contributor

@ianlancetaylor ianlancetaylor commented Oct 15, 2019

Do you see a change in behavior on the exact same machine?

@ianlancetaylor
Copy link
Contributor

@ianlancetaylor ianlancetaylor commented Oct 15, 2019

Oh, never mind, I know what this is. This is due to the fix for #30099. We used to mishandle dates before December 13, 1901, like the date you are testing in the year 0. Now we handle them correctly according the version of the tzdata database on your system. The standard tzdata records that the U.S. switched from local time zones (LMT == Local Mean Time) to what are now the standard timezones in 1883, so dates before 1883 are recorded as being in LMT. The offset for LMT in America/Los_Angeles is -7:52:58, which is why you are seeing these odd results.

Basically, timezones for very old dates are not very useful.

@golang golang locked and limited conversation to collaborators Oct 14, 2020
Sign up for free to subscribe to this conversation on GitHub. Already have an account? Sign in.
Projects
None yet
Linked pull requests

Successfully merging a pull request may close this issue.

None yet
3 participants
You can’t perform that action at this time.