x/mobile: build failing when using go modules

[axet]

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

go version go1.13.7 linux/amd64

Does this issue reproduce with the latest release?

yes

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

go env Output

GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/axet/.cache/go-build"
GOENV="/home/axet/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/axet/.go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/snap/go/5243"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/snap/go/5243/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/home/axet/local/libtorrent/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 -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build037966773=/tmp/go-build -gno-record-gcc-switches"

What did you do?

gomobile failed with "replacement module directory path ... cannot have version"

Probably because gomobile does not support 'go.mod replace command'. Full log:

# git clone -b dev https://gitlab.com/axet/libtorrent
# gomobile bind
gomobile: go build -buildmode=c-shared -o=/tmp/gomobile-work-296787665/android/src/main/jniLibs/armeabi-v7a/libgojni.so ./gobind failed: exit status 1
go: errors parsing go.mod:
/tmp/gomobile-work-296787665/src/go.mod:181: replacement module directory path "/home/axet/.go/pkg/mod/gitlab.com/axet/torrent@v0.0.0-20200205141541-92b4b9e7387e" cannot have version

It also failed with "proper" version like "v0.14.0" or "libtorrent-0.14.0"

[odeke-em]

Thank you for the report @axet!

Kindly cc-ing @bcmills @jayconrod.

[bcmills]

What version of the gomobile command are you using? (This seems like a duplicate of #27234.)

[axet]

Recent:

axet@axet-laptop:~$ gomobile version
gomobile version +0df4eb2 Wed Feb 5 17:02:28 2020 +0000 (android); androidSDK=/home/axet/Android/Sdk/platforms/android-29

[axet]

I probably know what is going on, If I init gomobile staying inside my library with "go.mod" directory it will fail. Doesn't matter where gomobile is located, only $PWD is matter.

export GOPATH=$HOME/.go
export PATH=$HOME/.go/bin:$PATH
export ANDROID_NDK_HOME=$ANDROID_HOME/ndk/19.2.5345600/

PWD=$HOME/local/libtorrent

go get golang.org/x/mobile/cmd/gomobile
gomobile init
ls go.mod

And now it bugged. Maybe it is not a bug, but error message a bit confusing.

[jayconrod]

cc @hyangah

[hyangah]

gomobile generates go.mod file based on the go list output influenced by the original go.mod. (https://github.com/golang/mobile/blob/0df4eb2385467a487d418c6358313e9e838256ae/cmd/gomobile/bind.go#L230)

It looks like the original file has

replace github.com/anacrolix/torrent v1.13.0 => gitlab.com/axet/torrent v0.0.0-20200205141541-92b4b9e7387e

and gomobile bind converted it to

replace github.com/anacrolix/torrent v1.13.0 => /usr/local/google/home/hakim/go/pkg/mod/gitlab.com/axet/torrent@v0.0.0-20200205141541-92b4b9e7387e v0.0.0-20200205141541-92b4b9e7387e

cc @hajimehoshi

[gopherbot]

Change https://golang.org/cl/218057 mentions this issue: cmd/gomobile: handle modules replaced by other versioned modules

[jayconrod]

One thing to watch out for: it's not generally safe to use module directories in the module cache as replacements. Replacement modules must have a go.mod file, and a directory in the cache won't have a go.mod file if the original module didn't.

[axet]

It is closed, but still failed to compile. Same library I build using old style GOPATH no problems, go.mod build failed with two errors, first run:

gcc: error: unrecognized command line option '-marm'; did you mean '-mabm'?

second run (same command: gomobile bind)

gomobile: go build -buildmode=c-shared -o=/tmp/gomobile-work-515390264/android/src/main/jniLibs/armeabi/libgojni.so ./gobind failed: exit status 1
go: cannot determine module path for source directory /tmp/gomobile-work-515390264/src (outside GOPATH, module path must be specified)

Example usage:
	'go mod init example.com/m' to initialize a v0 or v1 module
	'go mod init example.com/m/v2' to initialize a v2 module

Run 'go help mod init' for more information.

Should I create separate issue?

[dmitshur]

@axet Please do. You can refer to this issue if any of the information here is relevant. Thanks.