x/tools/gopls: autocomplete returns packages within excluded directories (per build.directoryFilters)

[gonzojive]

Related to #48939 and reproduced in a repository.

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

$ go version

Does this issue reproduce with the latest release?

Yes:

~/git/go-tools$ git log -n 1
commit fe932b4680bd8878524bfea7a12f7cf30e1e0438

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

go env Output

$ $ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/red/.cache/go-build"
GOENV="/home/red/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/red/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/red/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/red/git/gopls-bug-workspace-filters/go.mod"
GOWORK=""
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-build2678705596=/tmp/go-build -gno-record-gcc-switches"

What did you do?

1. Check out https://github.com/gonzojive/gopls-bug-workspace-filters
2. Open internal/activework/activework.go
3. Try to tab complete myl within a function. The autocomplete list will include a library in the generated_stuff dir, which is included in the build.directoryFilters exclusion list:

{
    "gopls": {
        "build.directoryFilters": [
            "-generated_stuff",
        ],
        "formatting.local": "github.com/api-definitions/keyval",
    },
}

What did you expect to see?

Packages in generated_stuff shouldn't be included in autocomplete list?

I can't tell if this is working as intended. It came up before in #37697, but I interpret the build.directoryFilters to mean that the generated_stuff folder should be ignored in this context as well: https://github.com/golang/vscode-go/blob/master/docs/settings.md#builddirectoryfilters.

What did you see instead?

mylib is included in the autocomplete list.

[gonzojive]

I came across a related issue: #42965

From browsing the source, I wonder if the call to imports.GetAllCandidates from completions.go could be altered to pass in a filter derived from the directoryFilters that gets used in the dirFound callback that imports.GetAllCandidates uses to limit what packages it scans.

[gonzojive]

This bug may also be a duplicate of #51265, not totally sure.

[findleyr]

I just implemented something similar to this in https://go.dev/cl/531417.

Notes on how to implement this:

• Thread through directory filters to where we do 'metadata'-based unimported completion
  • here, for package names
  • here, for package members
• Apply directory filters for each compiled go file in the package; if all are excluded, ignore the package. (or just pick the first file to consider).
• For any excluded package path, also filter from module cache completion implemented via completer.completionCallbacks

May not get to this for v0.14, which we want to cut ASAP to include a completion performance fix.