x/tools/cmd/goimports: inconsistency with go fmt

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

$ go version
go version go1.14 freebsd/amd64

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/ryan/.cache/go-build"
GOENV="/home/ryan/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="freebsd"
GOINSECURE=""
GONOPROXY=""
GONOSUMDB=""
GOOS="freebsd"
GOPATH="/home/ryan/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/freebsd_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
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=/tmp/go-build464992684=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Used the tools go fmt and goimports on the following file (a minimal test case):

package main

func f() {
	var d = struct {
		Shorty int
		Short int
		VeryMuchLongerFieldName int
	}{
		Shorty: 5,
		Short: 5,
		VeryMuchLongerFieldName: 5,
	}
}

Go fmt converts it to:

package main

func f() {
	var d = struct {
		Shorty                  int
		Short                   int
		VeryMuchLongerFieldName int
	}{
		Shorty:                  5,
		Short:                   5,
		VeryMuchLongerFieldName: 5,
	}
}

Goimports converts it to:

package main

func f() {
	var d = struct {
		Shorty                  int
		Short                   int
		VeryMuchLongerFieldName int
	}{
		Shorty: 5,
		Short:  5,
		VeryMuchLongerFieldName: 5,
	}
}

The two tools disagree. This results in them always trying to reformat each others' code.

Goimports starts to agree with gofmt if Shorty and Short are in the opposite order, so that the field length progresses upward; or if VeryMuchLongerFieldName is reduced to MuchLongerFieldName.

[dmitshur]

Did you build goimports command with Go 1.14, or is it an older binary? What does go version -m $(which goimports) print?

I can't reproduce this. I suspect your goimports binary was built with an older version of Go, where gofmt behavior was slightly different, and so it's producing formatting output consistent with that old version of Go.

Edit: Actually, I can reproduce this if I build goimports with Go 1.10. There was a change to gofmt behavior in Go 1.11 (see https://golang.org/doc/go1.11#gofmt). So your goimports binary is probably built with Go 1.10 or older. Can you confirm?

You were right, that was it. It works after updating goimports. Thanks for such a prompt response.