Support for building pure UWP apps in Rust

[jaigak]

This requires modifications to the Rust runtime so that it doesn't call prohibited APIs in a UWP app. Currently building a AppContainer app using Rust fails validation.

[bdbai]

Try using *-uwp-windows-* targets instead of *-pc-windows-* targets. Xargo is good at this cross compilation work.

Also see https://github.com/bdbai/firstuwp-rs (not completed though). Since authoring composable object is not implemented so far, it is cumbersome that we have to implement COM interfaces by hand.

[uhuntu]

Not sure if it is suitable to say here, but just FYI: https://github.com/uhuntu/win_ui

[jaigak]

Not sure if it is suitable to say here, but just FYI: https://github.com/uhuntu/win_ui

That's a desktop app, not a UWP app.

[kennykerr]

Yes, it's not that this isn't supported. It's just that we don't really have any good samples to share at the moment. Working on that! 😉

[kennykerr]

@robmikh also shared an example here: https://github.com/robmikh/minesweeper-rs/tree/uwp

Beyond that I'm focused on getting support in Rust for authoring WinRT types #81 as that's a major obstacle in getting support for things like Xaml and UWP apps.