perf(layout): const functions

[EdJoPaTo]

The layout can often contain things that are already known at compile time which speeds up things on runtime. Especially as render is called a lot.

With 0.26.0 the Rect::contains method is now accepting a Position. While contains is const, Position::new is not which triggered the creation of this PR. I switched to Position { x, y }, but the compiler should be able to do the same in const with ::new().

I added the lint to the layout module, but I don't really know what other plans of this project are in regard to configuring lints. I could also just remove the lint there, but mistakes like the current one will happen again as the code uses a lot of const already. Do you have other thoughts on how to configure the lints best?

I observed the missing_const_for_fn clippy lint in other areas of the library too, but it's mostly pointless there. Some Widgets and WidgetStates could get ::new() implementations which are const which would also allow for optimizations there.

Personally I also think that more clippy::pedantic and clippy::nursery lints could keep the code quality of ratatui consistent. Like in the current case many things are already const, but they are forgotten in other places as no lints are ensuring that.

[joshka]

Personally I also think that more clippy::pedantic and clippy::nursery lints could keep the code quality of ratatui consistent. Like in the current case many things are already const, but they are forgotten in other places as no lints are ensuring that.

+1 on these - the issue is that turning them on makes a lot of noise initially, so it's a bunch of work drilling down on the lint errors. Once it's in though things are really nice.