Rust Custom Toolchain Nix Shell

shell.nix

let
  rust-overlay = builtins.fetchTarball "https://github.com/oxalica/rust-overlay/archive/master.tar.gz";
  pkgs = import <nixpkgs> {
    overlays = [ (import rust-overlay) ];
  };
  toolchain = pkgs.rust-bin.fromRustupToolchainFile ./toolchain.toml;
in

pkgs.mkShell {
  packages = [
    toolchain
  ];

  nativeBuildInputs = with pkgs; [
    rustc
    cargo
    gcc
    rustfmt
    clippy
    rust-analyzer
  ];
  
  RUST_SRC_PATH = "${toolchain}/lib/rustlib/src/rust/library";
}