29 Aug 2026

Rust devshell on macOS

When I develop something, I want a devshell that needs nothing but Nix: no Xcode Command Line Tools, no homebrew, no impure global state. Here's my setup for Rust with fenix:

devshells.default = {
  packages =
    with pkgs;
    [
      # ...
      clang
      inputs'.fenix.packages.stable.toolchain
      # ...
    ];

  env = lib.optionals pkgs.stdenv.isDarwin [
    # Without Xcode, clang can't find the macOS SDK, so get it from nixpkgs
    {
      name = "SDKROOT";
      value = pkgs.apple-sdk_26;
    }
    # Some crates (e.g. aws-lc-sys) need -liconv at link time
    {
      name = "LIBRARY_PATH";
      value = "${pkgs.libiconv}/lib";
    }
  ];
};