Move autogen to its own crate, no longer run in build.rs

[Rua]

Autogen no longer runs each time you build Vulkano. Instead it builds with cargo run --bin autogen. The output files are placed in autogen/output.

I've also switched to the prettyplease crate for formatting the output, which seems to give somewhat better results than rustfmt.

[marc0246]

Could you please name the output directory out? I know this is me being extremely nit-picky but that's the convention for build artifact directories. Cargo names it this as well iirc.

[Rua]

Could you please name the output directory out? I know this is me being extremely nit-picky but that's the convention for build artifact directories. Cargo names it this as well iirc.

Actually, I suspect that rust-analyzer is having some trouble figuring out when code is including files from outside the crate's directory structure. Because it's failing to autocomplete any of the generated names. So I'm thinking of putting it in vulkano/autogen instead.

[marc0246]

I suspect that rust-analyzer is having some trouble figuring out when code is including files from outside the crate's directory structure

I was just about to comment about that haha. That's the same issue I ran into in #2648 which forced me to put include inside vulkano-shaders. I'm also uncertain about how sophisticated Cargo packaging is. It rewrites some paths but I haven't tested this.

[Rua]

How's this?

[marc0246]

Looks nice 👍

FTR here are my build timings before and after:

We shaved off 30% of our compile times 🎉 Ideally that build script wouldn't exist at all (it still needs to be compiled after all). I'm not sure it actually does anything since your windowing library should link that stuff. But that's a micro-optimization for the future.