use case: using zig cc to cross compile a cgo program for windows

[andrewrk]

Dowstream issue: golang/go#43886

main.go

package main

//int Add(int a, int b){
//    return a+b;
//}
import "C"
import "fmt"

func main() {
	a := C.int(10)
	b := C.int(20)
	c := C.Add(a, b)
	fmt.Println(c) // 30
}

CGO_ENABLED=1 GOOS=windows GOARCH=amd64 CC="zcc" CXX="zc++" go build main.go

zcc

#!/bin/sh
zig cc -target x86_64-windows-gnu $@

zc++

#!/bin/sh
zig c++ -target x86_64-windows-gnu $@

output:

# command-line-arguments
warning: unsupported linker arg: --compress-debug-sections=zlib-gnu

It produces main.exe but when run it segfaults in runtime.rt0_go() (called from main()). This is probably an issue with the go runtime, and the next step here will be to file a downstream error report with go.

[LaPingvino]

as mentioned in the Go issue, this is probably fixed by @zx2c4's fixes for Windows ARM64, which necessitates LLVM support. it seems like a "did never work before" issue.

[antonmedv]

Still not possible?

[LaPingvino]

Probably fixed with Go 1.18, which is not released yet. This also fixes the need for a workaround for invoking zig cc / zig c++.

[motiejus]

The test program works for me with go1.17 and zig 0.9.0 and when run under wine:

motiejus ~/x/go $ go version
go version go1.17 linux/amd64
motiejus ~/x/go $ zig version
0.9.0
motiejus ~/x/go $ wine ./main.exe 
30
motiejus ~/x/go $ 

Is behavior different on windows? Unfortunately, I don't have a machine to test it with.