One thing I'm not entirely sure is that whether we want winit-common and then dirs like apple/linux/etc inside of it or a crate per domain. Maybe winit-common with an apple module inside of it is better.

One thing I'm not entirely sure is that whether we want winit-common and then dirs like apple/linux/etc inside of it or a crate per domain. Maybe winit-common with an apple module inside of it is better.

I'm not sure either.

Building on the discussion in #4246, we might not even want to call it "linux" and "apple" - maybe rather winit_common::xkb + winit_common::core_foundation + winit_common::foundation?

Yeah, that's true, so I'd probably be infavour of the common module to just add stuff that could be needed by multiple backends to e.g. write handling that does the same thing on every platform. So probably a big common crate for stuff we need is a better options.

I moved it to winit-common, along with the XKB stuff.

Check it out, and let me know what you think?

I'd probably still move apple specific stuff into separate folder, like event_handler for now.

I put the event_handler at the top-level, because I plan to use it in the Web backend too.

We can also use the build.rs stuff we have to gate features that can not really build on platforms.

But the CoreFoundation stuff can build on more platforms - e.g. if you have certain GNUStep libraries installed, you can build winit-common/core_foundation on Linux.

Similarly, e.g. cargo build -pwinit-common --features wayland,xkb --target aarch64-apple-darwin works perfectly fine.

maybe group in objc it then, so it's a bit clear what it is about?

I guess I'm also fine with:

• xkb
• apple::EventLoopProxy - where "Apple" here would indicate the API, but not necessarily restrict it to Apple platforms only?
• interior_mutable::EventHandler?

(objc is wrong, since none of these APIs actually use Objective-C calls, they just use crates from the objc2 project).

But the CoreFoundation stuff can build on more platforms - e.g. if you have certain GNUStep libraries installed, you can build winit-common/core_foundation on Linux.

Can the AppKit backend be used on Linux? If not, then what's the point of the core_foundation code on Linux? A hypothetical separate GNUStep backend? (we don't want to compile any more code than is strictly necessary)

Can the AppKit backend be used on Linux?

Probably not functionally yet, but I think it'd be interesting to move towards that, yes.

(GNUStep contains CoreFoundation/Foundation/AppKit reimplementations).

(we don't want to compile any more code than is strictly necessary)

I've cfg-gated it already ;).