x/tools/gopls: `undeclared name` when using function from another file when both files have build tags

[asankov]

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

$ go version
go version go1.15.3 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
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/asankov/.cache/go-build"
GOENV="/home/asankov/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/asankov/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/asankov/go"
GOPRIVATE=""
GOPROXY="direct"
GOROOT="/usr/lib/golang"
GOSUMDB="off"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/golang/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/asankov/git/asankov/gira/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-build505007625=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I have a suite of integration tests files, all of which live in cmd/integrationtests folder, in a package named integrationtests.
I have a main file which includes functions for setting up the components like:

// integrationtests.go

// +build integration_tests

package integrationtests

import (...)

func setup(t *testing.T) *client.Client {
    // some implementation
    return nil
}

then I have different files with integration tests like users_test.go that use the setup function (without importing anything, because the function is in the same package) and it all works fine.

I created a new file in the same folder and package and when I tried to use the function I got the following error from VS Code:

undeclared name: setup compiler

Screenshot from the error:

NOTE: I do see that the error is coming from compile, not lsp, however when running go tool compile games_test.go integration_test.go I do not get any errors and I do not expect to get any errors, because what I am trying to do is valid, and I already do it in multiple files.

NOTE: The project I am working on is open source, so I can show you the package in question.

What did you expect to see?

I expected my code to be able to find the setup function.

What did you see instead?

Error: undeclared name: setup compiler

[heschik]

Please follow https://github.com/golang/tools/blob/master/gopls/doc/vscode.md#build-tags to configure the build tags you want to use.

[asankov]

Setting

"go.toolsEnvVars": {
        "GOFLAGS": "-tags=integration_tests"
    },

in settings.json resolved my problem. I guess what confused me was that it was working for some files, but not others. Closing now, thanks for the help.