cmd/go: `go work init .` adds `./.` instead of `.`

[bcmills]

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

~/src/golang.org/x/exp$ gotip version
go version devel go1.19-6da16b6ad Tue Mar 1 23:49:01 2022 +0000 linux/amd64

Does this issue reproduce with the latest release?

It reproduces with go1.18rc1, yes.

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

go env Output

~/src/golang.org/x/exp$ gotip env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/usr/local/google/home/bcmills/.cache/go-build"
GOENV="/usr/local/google/home/bcmills/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/tmp/tmp.dpCQFoAKTg/.gopath/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/tmp/tmp.dpCQFoAKTg/.gopath"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/google/home/bcmills/sdk/gotip"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/google/home/bcmills/sdk/gotip/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="devel go1.19-6da16b6ad Tue Mar 1 23:49:01 2022 +0000"
GCCGO="/usr/local/google/home/bcmills/bin/gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="c++"
CGO_ENABLED="1"
GOMOD="/usr/local/google/home/bcmills/src/golang.org/x/exp/go.mod"
GOWORK="/usr/local/google/home/bcmills/src/golang.org/x/exp/go.work"
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-build1424670007=/tmp/go-build -gno-record-gcc-switches"

What did you do?

~/src/golang.org/x/exp$ gotip work init .

~/src/golang.org/x/exp$ cat go.work

What did you expect to see?

go 1.19

use .

What did you see instead?

go 1.19

use ./.

CC @matloob

[bcmills]

The argument . should trigger modfile.IsDirectoryPath here:
https://cs.opensource.google/go/go/+/ce427cf96128b545ae473983bafb6a0b80ecaa08:src/cmd/go/internal/modload/modfile.go;l=805-807

But it doesn't: this looks like a bug in IsDirectoryPath, which does not expect to ever need to refer to a module in the same directory (compare #34417).

For Go 1.19, we should probably fix up modfile.IsDirectoryPath. For 1.18, perhaps we should change the condition to if path == "." || modfile.IsDirectoryPath(path).

[gopherbot]

Change https://go.dev/cl/389854 mentions this issue: cmd/go: make paths consistent between 'go work init' and 'go work use'

[gopherbot]

Change https://go.dev/cl/389298 mentions this issue: [release-branch.go1.18] cmd/go: make paths consistent between 'go work init' and 'go work use'

[bcmills]

Reopening for 1.18 backport.

[gopherbot]

Change https://go.dev/cl/389299 mentions this issue: [release-branch.go1.18] cmd/go: error out of 'go work use' if no directories are given