feat: add nix flake.nix

[RobWalt]

Connections

• the existing shell.nix file

Description

There are currently two major ways of using nix: With and without flakes. Currently the repo only hosts a shell.nix file which supports the non-flake way of running nix stuff like development shells. This PR adds a flake.nix and a modularized directory nix where people can find the implementation of the flake-devshell.

• Compared to the shell.nix file, this development shell only includes the necessary dependency to get the wgpu examples running. People are free to extend this minimal devshell and tailor it to their own needs.
• The flake approach also supports locking dependencies which helps with the reproducibility of everything.

Testing

• I entered the devShell on my machine and ran the hallmark example successfully. ✅

[cwfitzgerald]

I don't know how to review this in any seriousness, but idk it looks fine 😆

I am a bit worried about the growth of completely unrelated configurations to this repository - notably we do not have any ability to update them (none of us use nix) so they are probably going to atrophy without our knowledge and not be useful over the long term.

With the caviat that I do not completely understand the flow for nix-ians, but this feels like something that they would deal with on an individual level, or follow some template for rust graphics or something, as opposed to every repo having a flake.nix file for their own needs.

[teoxoy]

Tagging everyone that was involved in initial PR (#5519) for comments/review:

@MultisampledNight
@NyxAlexandra
@eddyb

[NyxAlexandra]

I think it would be nice to not duplicate dependency lists in shell.nix and nix/rust.nix. shell.nix seems to be a superset of nix/rust.nix, so it could be factored out with an import.

[teoxoy]

I am a bit worried about the growth of completely unrelated configurations to this repository - notably we do not have any ability to update them (none of us use nix) so they are probably going to atrophy without our knowledge and not be useful over the long term.

I agree with this as well. Since we can't guarantee that the config files will always be up to date, I don't see much benefit from them being hosted in the wgpu repo. Would it be possible to host the config files somewhere else (which wgpu could then link to)? Or is there another benefit to have them in repo?

[RobWalt]

Yeah that's probably also a valid option. I think we can close this here then, I'm fine with it. I'll create some templates and post them here once they're ready

[cwfitzgerald]

We should probably pull the other nix thing from the repo then.