A tiny Go code fails only on Travis CI for Linux

Environments Linux
#1

I have a strange behavior of Travis CI for Linux.
https://github.com/herumi/test-travis-release is a sample of it.
make test runs well in my local environments such as Ubuntu 18.04.4 LTS + go1.13.4(14.1) and macOS 10.14.
But it fails only on Travis CI for Linux (It runs well on Travis CI for macOS).
https://travis-ci.org/github/herumi/test-travis-release/builds/667614744

bls/bls.go:15:105: cannot use (*[8]_Ctype_char)(unsafe.Pointer(&buf[0])) (type *[8]_Ctype_char) as type unsafe.Pointer in argument to func literal

I think that it would cause an error in every environment if it is a syntax error.
Could you give me some advice?

#2

At the very least

  • you are using language: cpp rather than language: go for some reason and Xenial rather than Bionic
  • preinstalled Go version is 1.11.1, not 1.13.4
  • it likely uses GCC in Linux and CLang in OSX
#3

Thank you for the advice.
I tried many combinations but the results were the same.


https://travis-ci.org/github/herumi/test-travis-release/builds/667846719

The strangest thing for me is that it works well locally but not on travis, even if using the same version of Go.

#4

If something works locally but not in Travis, there are differences between your local environment and Travis.

Find out what this error message means and dig from there – only that can tell what the cause is and point to the discrepancy.

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#5

The code I pointed out is minimized from my large projects.
It is https://github.com/herumi/test-travis-release/blob/master/bls/bls.go

package bls

/*
#cgo LDFLAGS:-lbls
#cgo linux,amd64 LDFLAGS:-L${SRCDIR}/lib/linux/amd64
#cgo darwin,amd64 LDFLAGS:-L${SRCDIR}/lib/darwin/amd64
void blsFunc(const char buf[][8]);
*/
import "C"
import (
	"unsafe"
)

func BlsFunc(buf []byte) {
	C.blsFunc((*[8]C.char)(unsafe.Pointer(&buf[0])))
}

travis says:
bls/bls.go:15:105: cannot use (*[8]_Ctype_char)(unsafe.Pointer(&buf[0])) (type *[8]_Ctype_char) as type unsafe.Pointer in argument to func literal

But my all environments (Ubuntu/CentOS/Windows mingw/macOS + Go 1.12.10, 1.13.4, 1.14.1 and travis with macOS) say nothing.

#6

I asked this problem at go forum and got the answer that this Go code has no problem.
By checking of the result of go tool bls.go, I found that there are difference between Travis-mac-go and Travis-linux-go.

I think that this causes an error, but I don’t know why Travis-go puts it.

bls/bls.go:13:118: cannot use _cgo0 (type *[8]_Ctype_char) as type unsafe.Pointer in argument to _Cfunc_blsFunc

travis-linux-go

//go:cgo_unsafe_args

func _Cfunc_blsFunc(p0 unsafe.Pointer) (r1 _Ctype_void) {
    _cgo_runtime_cgocall(_cgo_e2f56382bf64_Cfunc_blsFunc, uintptr(unsafe.Pointer(&p0)))
    if _Cgo_always_false {
        _Cgo_use(p0)
    }
    return
}

travis-mac-go and all my local environments (linux/mac/mingw)

//go:cgo_unsafe_args

func _Cfunc_blsFunc(p0 *[8]_Ctype_char) (r1 _Ctype_void) {
    _cgo_runtime_cgocall(_cgo_e2f56382bf64_Cfunc_blsFunc, uintptr(unsafe.Pointer(&p0)))
    if _Cgo_always_false {
        _Cgo_use(p0)
    }
    return
}
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