cmd/go: no place to install binary-only packages in module mode

[oszika]

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

$ go version
go version go1.11 linux/amd64

Does this issue reproduce with the latest release?

Yes with Go1.11.1

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

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/oszika/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/oszika/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/lib/go"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
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-build421177302=/tmp/go-build -gno-record-gcc-switches"

What did you do?

I want to vendor binary-only-package using go mod.

What did you expect to see?

First, I have written the package to expose as binary-only :

package p1

import "fmt"

func F() { fmt.Println("") }

After build it, I have added //go:binary-only-package but build does not work anymore : go build p1: missing or invalid binary-only package; expected file "".
But it's normal, because there is no target using go mod. Futhermore, using p1 in another package returns the same error.

So, I have produced a library like that : go build -o p1.a. But I do not know where to put my library because $GOPATH/pkg is not used. And go mod vendor makes vendored copy of source only.

What did you see instead?

$GOPATH/pkg will be eliminated at next version. Is there a solution like binary-only-package?

Workaround

To workaround this trouble, I have used $GOROOT/pkg, but I think it's ugly.

[rsc]

In general binary-only packages are not too well supported, by design. In particular "go get" has never supported them. The assumption is that the binary distribution is happening in some other way. I am not 100% sure we need to keep them working at all. Perhaps we should admit defeat and just drop support for them entirely.

That said, it seems OK to look in GOPATH/pkg for the .a file for a binary-only package as a stop-gap.

[oszika]

Thank you for your response.

Indeed, binary-only-package seems to be hard to support.
Do you have an idea for another approach to provide a SDK?

[rsc]

@oszika, I would provide source code. That's what is guaranteed to work with all possible compilation settings.

[rsc]

Given the plan to remove binary-only packages (#28152) I don't think we need to make them module-compatible before removing them. Let's leave this alone.