cmd/go: go mod init fails to determine module path in subdirectory

[andig]

Please answer these questions before submitting your issue. Thanks!

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

1.11

Does this issue reproduce with the latest release?

yes

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

❯ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/andig/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/andig/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/Cellar/go/1.11/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.11/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD="/Users/andig/htdocs/goelster/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/73/89ycv7qn51j4kbm04jsz9b840000gn/T/go-build453007721=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

Trying to init go modules, I'm seing it fail from one folder but working from another. Both folders only contain two simple go files:

~/htdocs/canprogs/go master*
❯ go mod init
go: cannot determine module path for source directory /Users/andig/htdocs/canprogs/go (outside GOPATH, no import comments)

~/htdocs/goelster master
❯ go mod init
go: creating new go.mod: module github.com/andig/goelster

❯ ls
elster.go main.go

[bcmills]

Please attach the output of go env (as requested by the issue template).

[bcmills]

Which directory (if any) is at the root of your VCS checkout, and what is your GOPATH?

[andig]

Please attach the output of go env

Sorry, only noticed the "operating system" question, added go env above. ~/htdocs/canprogs is a git root, so is ~/htdocs/goelster. Neither is part of the gopath.

[andig]

@bcmills I see this has been scheduled- seems I've hit an actual issue here?

[xswordsx]

Have you tried go mod init <module_name>? (e.g. go mod init goelster)

[andig]

That creates a go.mod:

❯ go mod init goelster
go: creating new go.mod: module goelster

❯ cat go.mod
module goelster

is this the expected behavior?

[myitcv]

go mod init with no arguments does it's best to determine a module path if the current directory belongs to a VCS repository that has a remote:

$ cd $(mktemp -d)
$ git init
Initialized empty Git repository in /tmp/tmp.T8elQyoqel/.git/
$ git remote add origin https://github.com/myitcv/gobin
$ go mod init
go: creating new go.mod: module github.com/myitcv/gobin

You can alternatively provide an explicit argument, as you outlined in #27951 (comment).

The bug you correctly identified is that go mod init with no arguments does not do the correct thing in a subdirectory of the VCS repo root:

$ mkdir inner
$ cd inner
$ go mod init
go: cannot determine module path for source directory /tmp/tmp.T8elQyoqel/inner (outside GOPATH, no import comments)