x/tools/gopls: can't work on project in $GOPATH/pkg/mod

[jiacai2050]

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

$ go version
go version go1.13 darwin/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="auto"

GOARCH="amd64"

GOBIN=""

GOCACHE="/Users/chenxiang/Library/Caches/go-build"

GOENV="/Users/chenxiang/Library/Application Support/go/env"

GOEXE=""

GOFLAGS=""

GOHOSTARCH="amd64"

GOHOSTOS="darwin"

GONOPROXY=""

GONOSUMDB=""

GOOS="darwin"

GOPATH="/Users/chenxiang/code/go"

GOPRIVATE=""

GOPROXY="https://goproxy.cn,direct"

GOROOT="/Users/chenxiang/.goenv/versions/1.13.0"

GOSUMDB="sum.golang.org"

GOTMPDIR=""

GOTOOLDIR="/Users/chenxiang/.goenv/versions/1.13.0/pkg/tool/darwin_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=/var/folders/fq/zphbvlvx6bxbq03lts1v2dnr0000gp/T/go-build949244485=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Use emacs + gopls to navigate project in $GOPATH/pkg/mod

What did you expect to see?

No error

What did you see instead?

LSP :: Connected to [gopls:94397 status:starting].
LSP :: go [list -f {{context.GOARCH}} {{context.Compiler}} -- unsafe]: exit status 1: error writing go.mod: open $GOPATH/pkg/mod/github.com/cep21/circuit/v3@v3.1.0/go.mod298498081.tmp: permission denied

[gopherbot]

Thank you for filing a gopls issue! Please take a look at the Troubleshooting guide, and make sure that you have provided all of the relevant information here.

[ianthehat]

If you tried to directly open that folder, I would expect it to fail. gopls is designed to start from a valid project root (a writable source folder either in your GOPATH or with a go.mod and go.sum).

Nothing in $GOPATH/pkg/mod is a valid project, or should be opened directly as one, it is just a download cache for modules. The folders may not have correct go.mod files, and even if they do they are not writeable ones.

If you just want to explore the code, create a trivial project that depends on that module and open that instead.

[jiacai2050]

No, I don't use gopls in $GOPATH/pkg/mod directly, but rather jump there by lsp-find-definition from my own app.

[muirdm]

I don't have any issues poking around in the mod cache in Emacs. Are you using a using a current version of lsp-mode? Can you provide steps to reproduce the issue?

[bcmills]

Note that the combination of CL 204521 and CL 204878 (both upcoming in Go 1.14) will make go list, go test, etc. within the module cache much more likely to succeed.

That may also make the behavior of gopls more sensible for (read-only) workspaces within the module cache.

[bcmills]

(And #34506 makes it so that gopls could potentially even resolve missing dependencies.)