Use mold for linking when supported

Author: TymanWasTaken

flake.nix

@@ -34,12 +34,16 @@
                 rust' = (rust-bin.fromRustupToolchainFile ./rust-toolchain.toml);
                 # Setup rust nix packaging
                 craneLib = (crane.mkLib pkgs).overrideToolchain (_: rust');
+                stdenvSelector = p: if p.stdenv.hostPlatform.isElf then p.stdenvAdapters.useMoldLinker p.stdenv else p.stdenv;
                 commonArgs = {
                     src = craneLib.cleanCargoSource ./.;
                     strictDeps = true;
 
                     buildInputs = with pkgs; [ openssl ];
                     nativeBuildInputs = with pkgs; [ pkg-config ];
+
+                    # Use mold linker for faster builds on ELF platforms
+                    stdenv = stdenvSelector;
                 };
                 cargoArtifacts = craneLib.buildDepsOnly commonArgs;
                 commonArgsWithDeps = commonArgs // {
@@ -94,7 +98,11 @@
                         }
                     );
                 };
-                devShells.default = craneLib.devShell {
+                devShells.default = craneLib.devShell.override {
+                    mkShell = pkgs.mkShell.override {
+                        stdenv = stdenvSelector pkgs;
+                    };
+                } {
                     # Add all build-time dependencies to the environment
                     packages =
                         cranePackage.buildInputs