cmd/go: go work use panics when given a file

[JohnAnthony]

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

$ go version
1.18

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="/home/ja/go/bin"
GOCACHE="/home/ja/.cache/go-build"
GOENV="/home/ja/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/ja/go/pkg/mod"
GONOPROXY="*"
GONOSUMDB="*"
GOOS="linux"
GOPATH="/home/ja/go"
GOPRIVATE="*"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/home/ja/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/home/ja/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
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-build4125566826=/tmp/go-build -gno-record-gcc-switches"

What did you do?

$ mkdir work
$ cd work
$ go work init
$ touch iamafile
$ go work use iamafile

What did you expect to see?

A graceful error around having been provided a file instead of a folder

What did you see instead?

go: stat /home/ja/work/iamafile/go.mod: not a directory
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0x81d565]

goroutine 1 [running]:
cmd/go/internal/workcmd.runUse.func1({0x7ffc8a10a7ed?, 0x0?})
        /usr/local/go/src/cmd/go/internal/workcmd/use.go:97 +0x165
cmd/go/internal/workcmd.runUse({0xadc718?, 0xc000122000?}, 0xc00014c510?, {0xc00013a030, 0x1, 0x2?})
        /usr/local/go/src/cmd/go/internal/workcmd/use.go:112 +0xa8a
main.invoke(0xdb7660, {0xc00013a020, 0x2, 0x2})
        /usr/local/go/src/cmd/go/main.go:218 +0x2ee
main.main()
        /usr/local/go/src/cmd/go/main.go:175 +0x78e

[seankhliao]

cc @bcmills @matloob

[mvdan]

This seems like a good candidate for someone's first contribution, by the way. Just make sure to look at how recent bugfixes in go work were implemented, read https://go.dev/doc/contribute, and include a test case.

[JohnAnthony]

I'd be interested in working on this as a first contribution

[gopherbot]

Change https://go.dev/cl/393615 mentions this issue: cmd/go: prevent go work use panic when given a file

[bcmills]

@gopherbot, please backport to Go 1.18. (This is a user-facing panic in go work use.)

[gopherbot]

Backport issue(s) opened: #51764 (for 1.18).

Remember to create the cherry-pick CL(s) as soon as the patch is submitted to master, according to https://go.dev/wiki/MinorReleases.

[gopherbot]

Change https://go.dev/cl/394154 mentions this issue: cmd/go: prevent panic in go work use