text/template: key/value assignment is reversed within range loop

[jmooring]

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

go version go1.20.5 linux/amd64

Does this issue reproduce with the latest release?

Yes

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

go env Output

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/jmooring/.cache/go-build"
GOENV="/home/jmooring/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/jmooring/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/jmooring/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/snap/go/current"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/snap/go/current/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20.5"
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 -fdebug-prefix-map=/tmp/go-build988921665=/tmp/go-build -gno-record-gcc-switches"

What did you do?

package main

import (
	"os"
	"text/template"
)

func main() {

	a := [1]string{"value"}

	t := `
		{{ $k := "" }}
		{{ $v := "" }}
		{{ range $k, $v = . }}
			{{ $k }} = {{ $v }}
		{{ end }}
	`

	tmpl, err := template.New("test").Parse(t)
	if err != nil {
		panic(err)
	}

	err = tmpl.Execute(os.Stdout, a)
	if err != nil {
		panic(err)
	}
}

What did you expect to see?

0 = value

What did you see instead?

value = 0

Other

This is a regression, introduced when fixing #56490.

[ianlancetaylor]

@gopherbot Please open backport to 1.20.

This is a regression since previous versions.

[gopherbot]

Backport issue(s) opened: #60802 (for 1.20).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

[gopherbot]

Change https://go.dev/cl/503575 mentions this issue: text/template: set variables correctly in range assignment

[gopherbot]

Change https://go.dev/cl/503576 mentions this issue: [release-branch.go1.20] text/template: set variables correctly in range assignment