Update

flake.nix

@@ -7,6 +7,7 @@
   outputs = { self, nixpkgs, rust-overlay }: 
     let 
       # Overlays enable you to customize the Nixpkgs attribute set
+      rustExtensions = [ "rust-src" "rustfmt" "rust-analyzer" ];
       overlays = [
         # Makes a `rust-bin` attribute available in Nixpkgs
         (import rust-overlay)
@@ -14,7 +15,10 @@
         # create a Rust environment
         (self: super: {
           rustToolchain = super.rust-bin.stable.latest.default.override {
-            extensions = [ "rust-src" "rustfmt" "rust-analyzer" ];
+            extensions = rustExtensions;
+          };
+          rustNightlyToolchain = super.rust-bin.nightly.latest.default.override {
+            extensions = rustExtensions;
           };
         })
       ];
@@ -47,13 +51,15 @@
           packages = (with pkgs; [
             # The package provided by our custom overlay. Includes cargo, Clippy, cargo-fmt,
             # rustdoc, rustfmt, and other tools.
-            rustToolchain
+            rustNightlyToolchain
 
             python311
             cmake
             ninja
             libffi
             ccache
+
+            arcanist
           ]) ++ (with pkgs.llvmPackages_16; [
             libllvm
             clang