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ianlancetaylor opened this issue Aug 2, 2024 · 3 comments
Closed

time: AddDate with negative day changed behavior #68718

ianlancetaylor opened this issue Aug 2, 2024 · 3 comments
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NeedsFix The path to resolution is known, but the work has not been done.
Milestone
Go1.24

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@ianlancetaylor
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Go version

tip

Output of go env in your module/workspace:

GO111MODULE=''
GOARCH='amd64'
GOBIN=''
GOCACHE='/home/iant/.cache/go-build'
GOENV='/home/iant/.config/go/env'
GOEXE=''
GOEXPERIMENT=''
GOFLAGS=''
GOHOSTARCH='amd64'
GOHOSTOS='linux'
GOINSECURE=''
GOMODCACHE='/home/iant/gopath/pkg/mod'
GONOPROXY=''
GONOSUMDB=''
GOOS='linux'
GOPATH='/home/iant/gopath'
GOPRIVATE=''
GOPROXY='https://proxy.golang.org'
GOROOT='/home/iant/go'
GOSUMDB='sum.golang.org'
GOTMPDIR=''
GOTOOLCHAIN='auto'
GOTOOLDIR='/home/iant/go/pkg/tool/linux_amd64'
GOVCS=''
GOVERSION='devel go1.24-8659ad972f Wed Jul 24 00:40:06 2024 +0000'
GODEBUG=''
GOTELEMETRY='on'
GOTELEMETRYDIR='/home/iant/.config/go/telemetry'
GCCGO='gccgo'
GOAMD64='v1'
AR='ar'
CC='gcc'
CXX='g++'
CGO_ENABLED='1'
GOMOD='/dev/null'
GOWORK=''
CGO_CFLAGS='-O2 -g'
CGO_CPPFLAGS=''
CGO_CXXFLAGS='-O2 -g'
CGO_FFLAGS='-O2 -g'
CGO_LDFLAGS='-O2 -g'
PKG_CONFIG='pkg-config'
GOGCCFLAGS='-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -ffile-prefix-map=/tmp/go-build3145192880=/tmp/go-build -gno-record-gcc-switches'

What did you do?

package main

import (
	"fmt"
	"time"
)

const secondsPerDay = 24 * 60 * 60

func main() {
	date := time.Date(1899, time.December, 31, 0, 0, 0, 0, time.UTC)
	uday := int(date.Unix() / secondsPerDay)
	t := time.Unix(0, 0).AddDate(0, 0, uday)
	fmt.Println(t)
}

What did you see happen?

This is the output from Go tip following https://go.dev/cl/586257.

11761121-01-20 00:00:00 +0000 UTC

What did you expect to see?

This is the output from Go 1.23:

1899-12-31 00:00:00 +0000 UTC
@gabyhelp
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gabyhelp commented Aug 2, 2024

Related Issues and Documentation

(Emoji vote if this was helpful or unhelpful; more detailed feedback welcome in this discussion.)

@ianlancetaylor
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Testing a patch.

@gopherbot
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Change https://go.dev/cl/602815 mentions this issue: time: restore support for large negative days in Date

@dmitshur dmitshur added the NeedsFix The path to resolution is known, but the work has not been done. label Aug 2, 2024
@dmitshur dmitshur added this to the Go1.24 milestone Aug 2, 2024
@gabyhelp gabyhelp mentioned this issue Dec 31, 2024
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@dmitshur @ianlancetaylor @gopherbot @gabyhelp