Format removes imports of vendored packages in use

[sindrepm]

I just upgraded to the latest version and discovered a bug. When I have imports like the following:

import (
   "github.com/xanzy/go-gitlab"
   "github.com/emicklei/go-restful"
)

Whenever I save the file, those import lines are removed even if they are referenced in the code. This has worked fine up until the last upgrade so not sure what has happened. From what I have found, it only applies to packages which contains a hyphen as shown above (e.g. "go-gitlab" and "go-restful").

I have been able to reference these packages just by the "gitlab" or "restful" names before, but now it seems that the goimports tool doesn't like that? If I alias the imports with "gitlab" or "restful" it works and the lines are not removed.

It is quite an annoying bug so hopefully this can be fixed.

[AlekSi]

it only applies to packages which contains a hyphen as shown above

For me it's gopkg.in/Shopify/sarama.v1. I think this is due to package name is different from import path's last element.

It's really annoying.

[AlekSi]

It works with "go.formatTool": "gofmt". So my guess it is something between goreturns, GOPATH and vendor/.

[ramya-rao-a]

Can you run goreturns and/or goimports from the command line independent of VS Code and see if you still have the issue? This is to determine if the problem is with the formatting tool or with how VS Code uses the formatting tool.

[sindrepm]

I have tried running goreturns, goimports and gofmt directly on the .go file, and it works fine. The import lines are not removed. However, saving from the editor it immediately removes those imports.

[ramya-rao-a]

Can you share your settings?

[ramya-rao-a]

I tried the below code and I get build errors(syntax error: unexpected -, expecting expression), but no imports get removed on save

package main

import (
    "fmt"
    "github.com/emicklei/go-restful"
)

func main() {

    fmt.Println("Hello")
    go-restful.BodyParameter("hello", "bye")
}

[AlekSi]

My settings don't have anything Go-related except "go.gopath" with a single path.

Most, if not all, tools for Go (including gofmt, goimports and goreturns) work by parsing code into AST, modifying AST and printing it back. If Go code has syntax errors, it can't be parsed, and the tool just exits with an error message. That's why import is not removed by tool – tool did nothing.

Go differentiates between the last element of import path and package name. For github.com/xanzy/go-gitlab, github.com/emicklei/go-restful and gopkg.in/Shopify/sarama.v1 package names are gitlab, restful and sarama. I suspect some part of vscode-go assumes that last part of import path equals package name. It's often, but not always, true.

[AlekSi]

I created a small example: https://github.com/AlekSi/vscode-bug

[ramya-rao-a]

@AlekSi

Previously, the formatting tool (gofmt, goreturns, goimports) ran on the file on disk, which meant we had to save the file before running the format even if the user didn't want to.

As a means to fix that I had made the change to use stdin as input to the formatting tool instead of passing filename
This broke your scenario of vendor imports, because the formatting tool was unable to find the vendor packages.

Until the next update, as a workaround can you use gofmt as your choice of formatting tool?

@sindrepm
This need not be the same case as yours. Can you share a sample code where you are seeing the imports getting removed?

[sindrepm]

@ramya-rao-a

Thanks for the update. I am pretty sure my issue is the same as @AlekSi mentions. It can very easily be reproduce with this simplified code:

package main

import "github.com/xanzy/go-gitlab"

func main() {
    c := gitlab.Client{}
}

Try saving this file and the import line is removed. I do have github.com/xanzy/go-gitlab in my vendor folder.

Your workaround by changing go.formatTool to gofmt worked! With goreturns it fails.

[ramya-rao-a]

@sindrepm Great, the pkg is a vendor pkg for you too. The next update (mostly end of this week), should have the fix