I have a Proposal but I'm not sure if Its the right place to propose but as it has to do with building Swift So I'm going to submit here. So Please let me know if that is not the place to propose this feature. As it includes Xcode.
Ok So this is a proposal for being able to build swift for linux on Mac Os X in Xcode just like a native target.
With the release of Hypervisor.framework It would be good if from within Xcode I can create a project with a Linux Target and when clicking Build and run it create a VM running a small linux Kernel using Hypervisor.framework.
By using Hypervisor.framework it would be better integrated into the tools as it has a small foot print. The idea would be to have the VM downloaded before a build. The linux VM should be small and only have the required software to test a server and using the hypervisor.framework the project build folder can be attached to the vm at build time so the working with different projects at the same time would not require lots of VM.
Now I know that this would be best if integrated into Xcode and this is the Swift Language mailing list but Swift build is part of the Language.
This could also be used to debugging. Now Its possible now to use Docker to run a linux vm and have a shared folder for your project and some scripts to kick off the build. But it take time to setup per project and is not the Experience i would expect in Xcode.
Now My first thought when I found out about Hypervisor.framework that the reason it was created was to add linux targets to Xcode.