x/tools/gopls: data corruption on save

[josharian]

gopls version

$ gopls -v version
Build info
----------
golang.org/x/tools/gopls v0.11.0
    golang.org/x/tools/gopls@v0.11.0 h1:/nvKHdTtePQmrv9XN3gIUN9MOdUrKzO/dcqgbG6x8EY=
    github.com/BurntSushi/toml@v1.2.1 h1:9F2/+DoOYIOksmaJFPw1tGFy1eDnIJXg+UHjuD8lTak=
    github.com/google/go-cmp@v0.5.9 h1:O2Tfq5qg4qc4AmwVlvv0oLiVAGB7enBSJ2x2DqQFi38=
    github.com/sergi/go-diff@v1.1.0 h1:we8PVUC3FE2uYfodKH/nBHMSetSfHDR6scGdBi+erh0=
    golang.org/x/exp@v0.0.0-20221031165847-c99f073a8326 h1:QfTh0HpN6hlw6D3vu8DAwC8pBIwikq0AI1evdm+FksE=
    golang.org/x/exp/typeparams@v0.0.0-20221031165847-c99f073a8326 h1:fl8k2zg28yA23264d82M4dp+YlJ3ngDcpuB1bewkQi4=
    golang.org/x/mod@v0.7.0 h1:LapD9S96VoQRhi/GrNTqeBJFrUjs5UHCAtTlgwA5oZA=
    golang.org/x/sync@v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
    golang.org/x/sys@v0.2.0 h1:ljd4t30dBnAvMZaQCevtY0xLLD0A+bRZXbgLMLU1F/A=
    golang.org/x/text@v0.4.0 h1:BrVqGRd7+k1DiOgtnFvAkoQEWQvBc25ouMJM6429SFg=
    golang.org/x/tools@v0.3.1-0.20221213193459-ca17b2c27ca8 h1:7/HkGkN/2ktghBCSRRgp31wAww4syfsW52tj7yirjWk=
    golang.org/x/vuln@v0.0.0-20221109205719-3af8368ee4fe h1:qptQiQwEpETwDiz85LKtChqif9xhVkAm8Nhxs0xnTww=
    honnef.co/go/tools@v0.3.3 h1:oDx7VAwstgpYpb3wv0oxiZlxY+foCpRAwY7Vk6XpAgA=
    mvdan.cc/gofumpt@v0.4.0 h1:JVf4NN1mIpHogBj7ABpgOyZc65/UUOkKQFkoURsz4MM=
    mvdan.cc/xurls/v2@v2.4.0 h1:tzxjVAj+wSBmDcF6zBB7/myTy3gX9xvi8Tyr28AuQgc=
go: go1.20

go env

$ go env
GO111MODULE=""
GOARCH="arm64"
GOBIN="/Users/josh/bin"
GOCACHE="/Users/josh/Library/Caches/go-build"
GOENV="/Users/josh/Library/Application Support/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="arm64"
GOHOSTOS="darwin"
GOINSECURE=""
GOMODCACHE="/Users/josh/pkg/mod"
GONOPROXY="github.com/canopyclimate/www"
GONOSUMDB="github.com/canopyclimate/www"
GOOS="darwin"
GOPATH="/Users/josh"
GOPRIVATE="github.com/canopyclimate/www"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/Users/josh/go/1.20"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/Users/josh/go/1.20/pkg/tool/darwin_arm64"
GOVCS=""
GOVERSION="go1.20.3"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -arch arm64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/73/xx0jgm0j5ws5lqb8qngnqwc40000gn/T/go-build3159536453=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Put this code into a file (not using VSCode):

package main

func Match(data []byte) int {
//line :1
	var idx = ^uint(0)
	_ = idx
	return -1
}

Open in VSCode. Save (with formatting).

What did you expect to see?

No changes.

What did you see instead?

pge m:ain

func Match(data []byte) int {
//line :1
	var idx = ^uint(0)
	_ = idx
	return -1
}

This doesn't reproduce from the command line using gofmt or gofumpt or goimports.

Editor and settings

Some possibly(?) relevant snippets:

  "go.useLanguageServer": true,

  "gopls": {
    "formatting.gofumpt": true,
  },

  "editor.formatOnSave": true,

  "[go]": {
    "editor.defaultFormatter": "golang.go"
  },

  "go.formatTool": "goimports",

[findleyr]

Thanks for the report. This is already fixed at master (coincidentally, as we made several changes to handling of line directives).

I'll leave this open and add it to the v0.12.0 milestone to ensure we include a test for this bug.

[gopherbot]

Change https://go.dev/cl/490315 mentions this issue: gopls/internal/regtest/marker: add a test case for issue #59554