x/tools/gopls: .go files starting with "_" can cause error

[martinrode]

What version of Go, VS Code & VS Code Go extension are you using?

• go version

 go version go1.15.6 darwin/amd64

• gopls -v version

Build info
----------
golang.org/x/tools/gopls v0.6.0
    golang.org/x/tools/gopls@v0.6.1 h1:vD171EDBkyUVyp9B45IYXklV/VEfbHgX0FKw0Q0dO30=
    github.com/BurntSushi/toml@v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=
    github.com/google/go-cmp@v0.5.1 h1:JFrFEBb2xKufg6XkJsJr+WbKb4FQlURi5RUcBveYu9k=
    github.com/sergi/go-diff@v1.1.0 h1:we8PVUC3FE2uYfodKH/nBHMSetSfHDR6scGdBi+erh0=
    golang.org/x/mod@v0.3.0 h1:RM4zey1++hCTbCVQfnWeKs9/IEsaBLA8vTkd0WVtmH4=
    golang.org/x/sync@v0.0.0-20201020160332-67f06af15bc9 h1:SQFwaSi55rU7vdNs9Yr0Z324VNlrF+0wMqRXT4St8ck=
    golang.org/x/tools@v0.0.0-20201217163546-c88dec5c6b05 h1:4hzTNH658xirWc4MvAx9HK2/2hY6z42i1+lRK8OzeJE=
    golang.org/x/xerrors@v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
    honnef.co/go/tools@v0.0.1-2020.1.6 h1:W18jzjh8mfPez+AwGLxmOImucz/IFjpNlrKVnaj2YVc=
    mvdan.cc/gofumpt@v0.0.0-20200927160801-5bfeb2e70dd6 h1:z+/YqapuV7VZPvBb3GYmuEJbA88M3PFUxaHilHYVCpQ=
    mvdan.cc/xurls/v2@v2.2.0 h1:NSZPykBXJFCetGZykLAxaL6SIpvbVy/UFEniIfHAa8A=
- Run `code -v` or `code-insiders -v` to get version of VS Code or VS Code Insiders
	Version: 1.52.1
Commit: ea3859d4ba2f3e577a159bc91e3074c5d85c0523
Date: 2020-12-16T16:30:02.420Z
Electron: 9.3.5
Chrome: 83.0.4103.122
Node.js: 12.14.1
V8: 8.3.110.13-electron.0
OS: Darwin x64 20.1.0

go env

GO111MODULE="on"
GOARCH="amd64"
GOBIN="/Users/martin/go/bin"
GOCACHE="/Users/martin/Library/Caches/go-build"
GOENV="/Users/martin/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/martin/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="darwin"
GOPATH="/Users/martin/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/martin/go/src/github.com/programmfabrik/fylr/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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/4f/l31kb4n521d6g89qxrwcx69h0000gp/T/go-build409113686=/tmp/go-build -gno-record-gcc-switches -fno-common"

Share the Go related settings you have added/edited

    "go.vetOnSave": "off",
    "go.lintOnSave": "off",
    "go.delveConfig": {
        "useApiV1": false,
        "dlvLoadConfig": {
            "followPointers": true,
            "maxVariableRecurse": 3,
            "maxStringLen": 256,
            "maxArrayValues": 256,
            "maxStructFields": -1
        }
    },
    "go.languageServerExperimentalFeatures": {
    

        "diagnostics": true,
        "documentLink": true
    },
    "go.formatTool": "goimports",
    "go.buildOnSave": "workspace",
    "go.useLanguageServer": true

Describe the bug

In my project I have an obsolete "_claims.go" file which is not ignored by gopls, causing bugs:

[Error - 3:06:11 PM] 2021/01/05 15:06:11 no highlight: getting file for Highlight: go [-e -json -compiled=true -test=true -export=false -deps=true -find=false -- github.com/olivere/elastic/v7 github.com/programmfabrik/fylr/internal/api/acl github.com/programmfabrik/fylr/internal/api/datamodel github.com/programmfabrik/fylr/internal/indexer github.com/programmfabrik/fylr/internal/api/file github.com/programmfabrik/fylr/internal/api/fcontext github.com/programmfabrik/fylr/internal/baseconfig github.com/programmfabrik/fylr/internal/api/facet golang.org/x/xerrors github.com/programmfabrik/fylr/internal/util/iso8601 github.com/programmfabrik/fylr/internal/api/mapping github.com/programmfabrik/fylr/internal/api/transition github.com/programmfabrik/fylr/internal/api/privatetag github.com/dgrijalva/jwt-go github.com/programmfabrik/fylr/internal/api/object/enumerate github.com/programmfabrik/fylr/internal/api/event github.com/programmfabrik/fylr/internal/api/settings]: exit status 1: go: updates to go.sum needed, disabled by -mod=readonly

	URI=file:///Users/martin/go/src/github.com/programmfabrik/fylr/internal/api/_session/_claims.go

[Error - 3:06:11 PM] Request textDocument/formatting failed.
  Message: 82:2: expected statement, found '.'
  Code: 0 
[Error - 3:06:11 PM] 2021/01/05 15:06:11 imports fixes: AllImportsFixes: /Users/martin/go/src/github.com/programmfabrik/fylr/internal/api/_session/_claims.go:82:2: expected statement, found '.'
	file="/Users/martin/go/src/github.com/programmfabrik/fylr/internal/api/_session/_claims.go"

if I comment the package "github.com/dgrijalva/jwt-go" in _claims.go gopls works again.

With this bug, none of the features like "Show all occurrences" work.

"gopls" should ignore all files starting with "_", the same as "go build" does.

[hyangah]

@martinrode Thanks for the report.

@stamblerre According to https://tip.golang.org/cmd/go/#hdr-Package_lists_and_patterns, directory and file names beginning with "." or "_" should be ignored by the go tool.