Caching support on Windows

[tothambrus11]

Hi, I am Ambrus Tóth from the Hylo Language's developers. Thanks for developing this action, it's super useful! I would like to ask what's the reason that caching is not supported on Windows after Swift 5.10. Is this a limitation of the Swift compiler or this action? I would like to help fixing it if I can to speed up our CIs.
We are using Swift 6.1/6.2

[soumyamahunt]

Hi, I am Ambrus Tóth from the Hylo Language's developers. Thanks for developing this action, it's super useful!

Thank you @tothambrus11 . Glad that you found this action useful.

I would like to ask what's the reason that caching is not supported on Windows after Swift 5.10. Is this a limitation of the Swift compiler or this action?

It is not the limitation of the compiler rather the limitation of windows installer. Currently in Linux and macOS the installation method can install to a custom directory and caching of whole directory is easier. In windows, last I checked, the toolchain and runtime are installed in different locations with no way to customize the path. Also, the installation path keeps changing with different Swift versions.

I would like to help fixing it if I can to speed up our CIs.
We are using Swift 6.1/6.2

You can have a look at src/installer/windows/installation/approach.ts which implements caching for earlier versions. You can provide similar implementation for newer installation. You can add the new approach invocation here to use the new caching mechanism. The key part of the implementation is to finding out the installation location of different components which is easier if you have access to Windows device (can be done with CI but more time consuming).