x/mobile: iOS project won't compile with framework built by gomobile

[ibigbug]

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

$ go version
go version go1.12.6 darwin/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=""
GOCACHE="/Users/myname/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/myname/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/opt/go/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/opt/go/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
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 -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/cy/b0lrq2m55js29jlf_hhm4xtc0000gn/T/go-build880588199=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I created a go package and used gomobile to bind it for iOS:

gomobile bind -v  -target=ios mypackage

And then referenced the framework in my iOS project

Then complied the iOS project

What did you expect to see?

The project should compile

What did you see instead?

error messge

ld: in /PATH_TO_THE_FRAMEWORK(go.o), building for iOS, but linking in object file (/PATH_TO_THE_FRAMEWORK(go.o)) built for , for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

[bcmills]

CC @steeve @hyangah

[bcmills]

Then complied the iOS project

Please provide more concrete steps to reproduce the failure. What commands did you run to compile the project? Which command specifically produced the observed error message?

[steeve]

Is the problem in Xcode or gomobile build?
@ibigbug, can you please provide a sample project ?

cc @eliasnaur

[ibigbug]

Thanks guys for prompt reply.

I created a sample reproduce here https://github.com/ibigbug/SampleGomobile and put the steps in the README file.

A bit more information might be helpful, I'm using the latest Xcode beta. and it worked with an older version of gomobile, it compiles, but output of that version of gomobile doesn't have bitcode, so I upgraded to the latest gomobile and see this issue.

[ibigbug]

ping @steeve @bcmills

I'm using buildmode with c-archive to workaround this, but would be great to know how to fix this

[bcmills]

@ibigbug, this issue has the help wanted label because the solution is not obvious to me, and I don't know of anyone on the Go project who has the available bandwidth to look into it.

[steeve]

I believe this is linked to golang/mobile@9487ef5

You can either:

• revert that commit (or jump before it)
• try go 1.13, which this commit requires (because it has the bitcode commits)

[ibigbug]

thanks @steeve

Using go1.13beta is and manually passing CGO_FLAGS with -fembed-bitcode worked for me.

Though I'm building c-archive directly via go build, I haven't tried gomobile again, but I assume it would also work.