go 1.5 cross compile using cgo on OS X to linux and windows

Question

I'm having trouble compiling the git2go library on OS X to linux amd64 after upgrading go 1.4.2 to go 1.5.

I think this is about cross compiling any go app that uses C code with go 1.5.

Using CGO_ENABLED=1, I get:

$ CGO_ENABLED=1 GOOS=linux GOARCH=amd64 ./script/with-static.sh go install ./...
# runtime/cgo
ld: unknown option: --build-id=none
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Using -compiler=gccgo, I get:

$ GOOS=linux GOARCH=amd64 ./script/with-static.sh go install -compiler gccgo ./...
go build github.com/libgit2/git2go: : fork/exec : no such file or directory

If not supplying any of those, I get:

$ GOOS=linux GOARCH=amd64 ./script/with-static.sh go install ./...
can't load package: package github.com/libgit2/git2go: C source files not allowed when not using cgo or SWIG: wrapper.c

I installed go using homebrew, and I have the $GOPATH pointing to the default ~/go location, nothing fancy.

Answer 1

cgo is not enabled by default when cross compiling. If you enable cgo, with CGO_ENABLED=1 you will need to have a cross compiling c compiler for the target machine. This is non trivial.

I recommend, if you need cgo, to compile natively.

Answer 2

If you need cgo cross compilation, I'd point you to xgo, which I found immensely helpful. It didn't work in 100% of my use cases, but with some minor (compared to maintaining native VMs for cross-compiling) changes to my code, it was sufficient.