Cross-compiler for building "darwin" target

[Anders Björklund]

Description

It would be nice to be able to build all targets, before having it fail in CI on a VM

Something like https://github.com/neilotoole/xcgo and use a container builder?

Main issue is that github.com/Code-Hex/vz/v3 doesn't build (cgo).

Not sure if darwin is still open enough, or if it would need a mock?

---

i.e. trying to build with GOOS=darwin, from a Linux host

# github.com/Code-Hex/vz/v3
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:11:8: undefined: VirtualMachineStateStopped
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:12:8: undefined: VirtualMachineStateRunning
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:13:8: undefined: VirtualMachineStatePaused
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:14:8: undefined: VirtualMachineStateError
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:15:8: undefined: VirtualMachineStateStarting
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:16:8: undefined: VirtualMachineStatePausing
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:17:8: undefined: VirtualMachineStateResuming
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:18:8: undefined: VirtualMachineStateStopping
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:19:8: undefined: VirtualMachineStateSaving
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:27:9: undefined: VirtualMachineState
../go/pkg/mod/github.com/!code-!hex/vz/v3@v3.1.0/virtualmachinestate_string.go:19:8: too many errors

Being able to run unit tests (with binfmt_misc) would be nice.

i.e. similar to current GOOS=windows support (as in 8028e50)

Integration and release tests still need hardware, of course.

[Anders Björklund]

https://github.com/tpoechtrager/osxcross

https://github.com/multiarch/crossbuild

#cgo darwin CFLAGS: -mmacosx-version-min=11 -x objective-c -fno-objc-arc
#cgo darwin LDFLAGS: -lobjc -framework Foundation -framework Virtualization -framework Cocoa

#import <Availability.h>
#import <Cocoa/Cocoa.h>
#import <Foundation/Foundation.h>
#import <Virtualization/Virtualization.h>

[Anders Björklund]

This seems to be what I want, for running the unit tests (similar to wine for windows):

https://www.darlinghq.org/

~ $ uname
Linux
~ $ darling shell
Darling [~]$ uname
Darwin

It doesn't have to be perfect.

[Akihiro Suda]

This seems challenging in both technological and legal aspects.
It is unlikely that we can work on this.😢

[Anders Björklund]

The legal was supposed to be covered, if not it should be avoided for sure.

We only directly use those parts of Darwin that are released as fully free software.

---

But, like Wine, I don't think it is something that is needed upstream.
If the user have such an environment already, they can "just use it"...
If not, they would have to remote to a real Windows or Darwin machine.
(like the VMs that are being used in the GitHub Action workflows in CI)

Also, for testing purposes the no_vz tag avoided most* of the build issues...

* except for my copy/paste errors in the vz driver code itself, that is :-)

There are some odd modules that still refuse to cross-compile, not sure why?

# github.com/lima-vm/lima/pkg/hostagent
pkg/hostagent/inotify_darwin.go:6:47: undefined: notify.FSEventsInodeMetaMod

[Anders Björklund]

The cgo compilation failed, when trying to run cc -E -dM to get some macro definitions:

clang: error: argument unused during compilation: '-arch x86_64' [-Werror,-Wunused-command-line-argument]

That is, there was no actual code being compiled but it wanted to get a enum value...

	FSEventsInodeMetaMod          = 0x00400