docs - modernized nix linux dependencies example

[octocron]

Objective

• Changed buildInputs to packages (recommended way for mkShell since 22.05)
• Removed outdated RUST_SRC_PATH no longer needed as rust-analyzer added to extension list
• pkg-config moved to nativeBuildInputs because it is a build time tool, not a runtime library (package - buildInput)
• Use stdenv.isLinux instead of (lib.strings.hasInfix "linux" system) as it is cleaner, clearer and safer
• Made LD_LIBRARY_PATH part of platform check

Solution

• Updates the Nix example in the Linux dependencies documentation to use current best practices:
• Uses packages instead of the older buildInputs in mkShell
• Moves pkg-config to its proper place: nativeBuildInputs
• Uses stdenv.isLinux for platform checks

Testing

Test flake: https://gitlab.com/megacron/echo-chamber

• This code was tested in both Nixos and Mac environments using nix develop.
• It made the devshell environments properly for both platforms.
• Successfully ran cargo check and cargo run on both linux and macos with bevy window spawn, no errors.

[github-actions]

Welcome, new contributor!

Please make sure you've read our contributing guide, as well as our policy regarding AI usage, and we look forward to reviewing your pull request shortly ✨

[SpecificProtagonist]

I'm far from a nix expert, but – trying it out on NixOS – this works and the changes seem sensible to me.

[RLangendam]

Instead of putting this in the documentation, why don't we create the flake.nix and flake.lock at the repository root? This way we can transition the CI builds to use it and we have reproducible builds.

[RLangendam]

Instead of putting this in the documentation, why don't we create the flake.nix and flake.lock at the repository root? This way we can transition the CI builds to use it and we have reproducible builds.

Created a new PR (with slightly improved flake compared to the docs): #24872