Initial commit

fenix.nix

@@ -0,0 +1,67 @@
+fenixFlake:
+{ config, inputs, lib, flake-parts-lib, ... }:
+with builtins;
+let
+  inherit (lib) mkDefault mkOption types;
+  inherit (flake-parts-lib) mkPerSystemOption;
+  cfg = config.rust.fenix;
+in
+{
+  options = {
+    rust.fenix = {
+      manifestFile = mkOption {
+        type = types.path;
+      };
+
+      channel = mkOption {
+        type = types.str;
+        default = "stable";
+      };
+
+      components = mkOption {
+        type = types.listOf types.str;
+      };
+
+      targetComponents = mkOption {
+        type = types.attrsOf (types.listOf types.str);
+      };
+    };
+
+    perSystem = mkPerSystemOption {
+      _file = ./fenix.nix;
+      options = {
+        rust.fenix.toolchain = mkOption {
+          type = types.package;
+          readOnly = true;
+        };
+      };
+    };
+  };
+
+  config.rust.fenix = {
+    components = [
+      "cargo"
+      "rustc"
+    ];
+  };
+
+  config.perSystem = { pkgs, system, inputs', ... }: {
+    _module.args.fenixToolchain =
+      let
+        fenix = fenixFlake.packages.${system};
+
+        inherit (fenix) combine;
+
+        nativeToolchain = fenix.fromManifestFile cfg.manifestFile;
+        targetToolchain = t: fenix.targets.${t}.fromManifestFile cfg.manifestFile;
+
+        component = tc: c: getAttr c tc;
+        components = tc: cs: map (component tc) cs;
+        nativeComponents = components nativeToolchain cfg.components;
+        targetComponents = concatMap
+          (t: components (targetToolchain t) cfg.targetComponents.${t})
+          (attrNames cfg.targetComponents);
+      in
+      combine (nativeComponents ++ targetComponents);
+  };
+}