nix shell for building picosystem-rs things (https://github.com/rlane/picosystem-rs)

picosystem-rs-env.nix

{ srcs ? import ./nix/sources.nix }:
let
  pkgs = import srcs.nixpkgs {
    crossSystem = (import "${srcs.nixpkgs}/lib").systems.examples.raspberryPi // {
      rustc.config = "thumbv6m-none-eabi";
    };
  };
in

pkgs.mkShell {
  buildInputs = with pkgs; [
    cargo
    cargo-watch
    clippy

    rustc
    rustfmt

    pkg-config
    libudev
  ];
  # For openssl-sys crate
  PKG_CONFIG_PATH = "${pkgs.libudev.dev}/lib/pkgconfig";
  # See https://discourse.nixos.org/t/rust-src-not-found-and-other-misadventures-of-developing-rust-on-nixos/11570/3?u=samuela.
  RUST_SRC_PATH = "${pkgs.rust.packages.stable.rustPlatform.rustLibSrc}";
}

Unfortunately this builds rustc from source :/