default.nix: init

Move recipes from flake.nix:s `packages` to a `callPackage`-able scope.nix.
This way out-of-tree projects can reuse the `buildRustPackage`
definitions (e.g. the in-sync `cargoLock` hashes) without depending on
the unsupported flakes feature.

default.nix

@@ -0,0 +1,22 @@
+let
+  lockFile = builtins.fromJSON (builtins.readFile ./flake.lock);
+  flake-compat-node = lockFile.nodes.${lockFile.nodes.root.inputs.flake-compat};
+  flake-compat = builtins.fetchTarball {
+    inherit (flake-compat-node.locked) url;
+    sha256 = flake-compat-node.locked.narHash;
+  };
+
+  flake' = (
+    import flake-compat {
+      src = ./.;
+    }
+  );
+  flake = flake'.defaultNix;
+in
+{
+  useFlake ? true,
+  nixpkgs ? if useFlake then flake.inputs.nixpkgs else <nixpkgs>,
+  pkgs ? import nixpkgs { },
+}:
+
+pkgs.callPackage ./scope.nix { }

flake.lock

@@ -1,5 +1,19 @@
 {
   "nodes": {
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1751685974,
+        "narHash": "sha256-NKw96t+BgHIYzHUjkTK95FqYRVKB8DHpVhefWSz/kTw=",
+        "rev": "549f2762aebeff29a2e5ece7a7dc0f955281a1d1",
+        "type": "tarball",
+        "url": "https://git.lix.systems/api/v1/repos/lix-project/flake-compat/archive/549f2762aebeff29a2e5ece7a7dc0f955281a1d1.tar.gz?rev=549f2762aebeff29a2e5ece7a7dc0f955281a1d1"
+      },
+      "original": {
+        "type": "tarball",
+        "url": "https://git.lix.systems/lix-project/flake-compat/archive/main.tar.gz"
+      }
+    },
     "flake-parts": {
       "inputs": {
         "nixpkgs-lib": [
@@ -38,6 +52,7 @@
     },
     "root": {
       "inputs": {
+        "flake-compat": "flake-compat",
         "flake-parts": "flake-parts",
         "nixpkgs": "nixpkgs"
       }

flake.nix

@@ -3,6 +3,10 @@
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-parts.url = "github:hercules-ci/flake-parts";
     flake-parts.inputs.nixpkgs-lib.follows = "nixpkgs";
+    flake-compat = {
+      url = "https://git.lix.systems/lix-project/flake-compat/archive/main.tar.gz";
+      flake = false;
+    };
   };
 
   outputs =
@@ -16,27 +20,7 @@
       perSystem =
         { pkgs, ... }:
         let
-          buildEnvVars = {
-            BIN_XDG_PERMISSION_STORE = "${pkgs.xdg-desktop-portal}/libexec/xdg-permission-store";
-            BIN_XDG_DOCUMENT_PORTAL = "${pkgs.xdg-desktop-portal}/libexec/xdg-document-portal";
-            BIN_VIRTIOFSD = "${pkgs.virtiofsd}/bin/virtiofsd";
-          };
-
-          rustPackage =
-            crate:
-            let
-              cargoToml = builtins.fromTOML (builtins.readFile ./${crate}/Cargo.toml);
-            in
-            pkgs.rustPlatform.buildRustPackage {
-              inherit (cargoToml.package) name version;
-              src = ./.;
-              cargoLock.lockFile = ./Cargo.lock;
-              cargoLock.outputHashes = {
-                "busd-0.5.0" = "sha256-IZZ2MeEmUbzRrH6SUz0pnecMH4f8Mh54WdhI4q44YfI=";
-              };
-              buildAndTestSubdir = crate;
-              env = buildEnvVars;
-            };
+            scope = pkgs.callPackage ./scope.nix { };
         in
         {
           devShells.default = pkgs.mkShell {
@@ -46,11 +30,11 @@
               rust-analyzer
               clippy
             ];
-            env = buildEnvVars;
+            env = scope.buildEnvVars;
+          };
+          packages = {
+              inherit (scope) sidebus-agent sidebus-broker;
           };
-
-          packages.sidebus-agent = rustPackage "sidebus-agent";
-          packages.sidebus-broker = rustPackage "sidebus-broker";
         };
 
       flake = {

scope.nix

@@ -0,0 +1,41 @@
+{ lib, newScope }:
+
+lib.makeScope newScope (self: {
+  forgetScope = lib.flip lib.removeAttrs [
+    "override"
+    "overrideDerivation"
+    "overrideScope"
+    "newScope"
+    "packages"
+    "forgetScope"
+  ];
+  buildEnvVars = self.forgetScope (
+    self.callPackage (
+      { xdg-desktop-portal, virtiofsd }:
+      {
+        BIN_XDG_PERMISSION_STORE = "${xdg-desktop-portal}/libexec/xdg-permission-store";
+        BIN_XDG_DOCUMENT_PORTAL = "${xdg-desktop-portal}/libexec/xdg-document-portal";
+        BIN_VIRTIOFSD = "${virtiofsd}/bin/virtiofsd";
+      }
+    ) { }
+  );
+  rustPackage =
+    {
+      crate,
+      cargoToml ? builtins.fromTOML (builtins.readFile ./${crate}/Cargo.toml),
+      rustPlatform,
+      buildEnvVars,
+    }:
+    rustPlatform.buildRustPackage {
+      inherit (cargoToml.package) name version;
+      src = ./.;
+      cargoLock.lockFile = ./Cargo.lock;
+      cargoLock.outputHashes = {
+        "busd-0.5.0" = "sha256-IZZ2MeEmUbzRrH6SUz0pnecMH4f8Mh54WdhI4q44YfI=";
+      };
+      buildAndTestSubdir = crate;
+      env = buildEnvVars;
+    };
+    sidebus-agent = self.callPackage self.rustPackage { crate = "sidebus-agent"; };
+    sidebus-broker = self.callPackage self.rustPackage { crate = "sidebus-broker"; };
+})