cmd/go: executables are sometimes named after their module's last element, not directory

[spenczar]

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

go1.11

Does this issue reproduce with the latest release?

yes

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

darwin amd64

What did you do?

In a package main's directory (specifically, github.com/twitchtv/twirp/protoc-gen-twirp), I had a go.mod like this:

module github.com/twitchtv/twirp/protoc-gen-twirp/v5

I then ran GO111MODULE=on go build . from within $GOPATH/src/github.com/twitchtv/twirp/protoc-gen-twirp.

I expected an executable named protoc-gen-twirp, because that is the last element of the directory. This is the documented behavior in https://tip.golang.org/cmd/go/#hdr-Compile_packages_and_dependencies:

When compiling a single main package, build writes the resulting executable to an output file named after the first source file ('go build ed.go rx.go' writes 'ed' or 'ed.exe') or the source code directory ('go build unix/sam' writes 'sam' or 'sam.exe').

Instead, an executable was produced named v5.

However, if I invoke go build with a full path, I get the expected name. GO111MODULE=on go build github.com/twitchtv/twirp/protoc-gen-twirp produces an executable named protoc-gen-twirp.

This is either a documentation error, or a bug.

[mvdan]

cc @bcmills @rsc @myitcv

[myitcv]

Confirmed.

export GOPATH=$(mktemp -d)
cd $(mktemp -d)
mkdir hello
cd hello
go mod init example.com/hello/v6
cat <<EOD > main.go

package main

func main() {}
EOD
go build .

Now:

$ ls
go.mod  main.go  v6

But:

$ go install
$ ls $GOPATH/bin
hello

go install was fixed in #24667; sounds like a similar fix needed for go build.

[gopherbot]

Change https://golang.org/cl/140863 mentions this issue: cmd/go: fix the default build output name for versioned binaries

[FiloSottile]

If this does not land before RC1 (in the next couple of days), open a backport issue if it should be cherry-picked into 1.12.

/cc @hyangah

[gopherbot]

Change https://golang.org/cl/157798 mentions this issue: cmd/go: fix the default build output name for versioned binaries

[robfordww]

Modules with name 'example.com/mymodule.git' ,where the .git extension is used to trigger the local VCS command, get a binary named mymodule.git.exe. Shouldn't '.git' be stripped?

[chappjc]

If this does not land before RC1 (in the next couple of days), open a backport issue if it should be cherry-picked into 1.12.

/cc @hyangah

Looks like it didn't make 1.12. I don't know how a backport issue is started, but if this could be cherry-picked into 1.12 I'd be very happy.

[mvdan]

@gopherbot please backport to 1.12

[gopherbot]

Backport issue(s) opened: #30266 (for 1.12).

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

[ianlancetaylor]

Are we trying to get https://golang.org/cl/140863 into 1.12? @hyangah @bcmills

[mvdan]

@ianlancetaylor from the "backport" wording earlier, I presume 1.12.1 was meant.

[bcmills]

@mvdan is correct: we're targeting 1.12.1.

[gopherbot]

Change https://golang.org/cl/167384 mentions this issue: [release-branch.go1.12] cmd/go: fix the default build output name for versioned binaries

[gopherbot]

Change https://golang.org/cl/167617 mentions this issue: Revert "[release-branch.go1.12] cmd/go: fix the default build output name for versioned binaries"

[gopherbot]

Change https://golang.org/cl/167503 mentions this issue: cmd/go: fix the default build output name for versioned binaries

[dmitshur]

Reopening because the original CL 140863 was reverted on master branch via CL 168402.

[gopherbot]

Change https://golang.org/cl/168958 mentions this issue: [release-branch.go1.12] cmd/go: fix the default build output name for versioned binaries