x/tools/internal/imports: redundant import name is not removed

[nd]

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

$ go version
go version go1.12.6 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

$ go env
GOARCH="amd64"

GOBIN=""

GOCACHE="/home/nd/.cache/go-build"

GOEXE=""

GOFLAGS=""

GOHOSTARCH="amd64"

GOHOSTOS="linux"

GOOS="linux"

GOPATH="/home/nd/go"

GOPROXY=""

GORACE=""

GOROOT="/home/nd/go/go1.12.6"

GOTMPDIR=""

GOTOOLDIR="/home/nd/go/go1.12.6/pkg/tool/linux_amd64"

GCCGO="gccgo"

CC="gcc"

CXX="g++"

CGO_ENABLED="1"

GOMOD="/home/nd/p/golang-tools/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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build074254564=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I've ran goimports built on revision 2e34cfc on the following file:

package main

import opentracing "github.com/opentracing/opentracing-go"

func main() {
	println(opentracing.Binary)
}

What did you expect to see?

The redundant import alias is removed.

What did you see instead?

Nothing is changed.

Looks like introduced by 9bea2ec: the imp.name != "" check prevents redundant import cleanup.

[heschi]

cc @suzmue, but I think that commit just moved around existing code.

I'm not sure goimports has ever been able to do this, so it's more of a feature request than a bug, but I think it's a reasonable one. Just to confirm: if you remove the import name manually, it stays gone?

[nd]

Hmm, I was under impression that goimports removed redundant aliases, but it seems I was wrogn. Yes, if I remove the alias it is not added back.

[mitar]

So this is the function which extracts "perceived" name from the import path. It has some exceptions. So for github.com/go-ozzo/ozzo-dbx it extracts ozzo (and because this does not match dbx, dbx alias is added). And for github.com/opentracing/opentracing-go it extracts opentracing. This is why it does NOT add opentracing alias, because the extracted "perceived" name matches the package name.

What this issue is above is a feature request that unnecessary aliases (those which do match extracted "perceived" name and the package name) should be removed. goimports does not remove aliases if you have:

import (
        opentracing "github.com/opentracing/opentracing-go"
        http "net/http"
        fmt "fmt"
)

And this issue is that these aliases should be removed. In all these cases. I agree.