x/mobile: Failed to build GO app for android platform

[mehulhirpara]

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

$ go version
go version go1.11.1 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

$ go env
GOARCH="amd64"
GOBIN="/home/mhirpara/work/go/bin"
GOCACHE="/home/mhirpara/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/mhirpara/work/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-build255459644=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Trying to compile below GO app, which include C calls, for android platform.

package main

// #include <unistd.h>
// int
// am_session_leader()
// {
//   return (getsid(0));
// }
import "C"
import (
	"fmt"
)

func main() {
	fmt.Println(C.am_session_leader())
}

What did you expect to see?

Expectation is to build this app for Android Platform, just like other platforms and should be able to run.

What did you see instead?

I see build errors as below:

# command-line-arguments
./main.go:7: error: undefined reference to 'getsid'
./main.go:7: error: undefined reference to 'getsid'
clang70: error: linker command failed with exit code 1 (use -v to see invocation)
# command-line-arguments
./main.go:7:12: warning: implicit declaration of function 'getsid' is invalid in C99 [-Wimplicit-function-declaration]

Commands:

GOOS=android GOARCH=arm GOROOT=/usr/lib/go CGO_ENABLED=1 CC=/home/mhirpara/work/go/pkg/gomobile/ndk-toolchains/arm/bin/arm-linux-androideabi-gcc go build main.go

OR

gomobile build -x -target=android github.com/mehulhirpara/learning/cgo-getsid

[mehulhirpara]

FYI, so far this issue is observed only for android/arm and not for android/arm64