✨♻️ ci, nix, rust: Set up CI and switch to rust-overlay toolchain

- Added `.github/workflows/test.yaml` to run `cargo test` on push and pull_request events.
- Replaced `fenix` with `rust-overlay` in flake inputs for Rust toolchain management.
- Added `rust-toolchain.toml` specifying stable Rust with required components and targets.
- Updated `flake.nix` to use `rust-bin.fromRustupToolchainFile` and removed `RUST_SRC_PATH`.

.github/workflows/test.yaml

@@ -0,0 +1,15 @@
+name: Test
+
+on:
+  - push
+  - pull_request
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: cachix/install-nix-action@v27
+        with:
+          github_access_token: ${{ secrets.GITHUB_TOKEN }}
+      - run: nix develop -c cargo test

flake.lock

@@ -15,25 +15,6 @@
         "type": "github"
       }
     },
-    "fenix": {
-      "inputs": {
-        "nixpkgs": "nixpkgs",
-        "rust-analyzer-src": "rust-analyzer-src"
-      },
-      "locked": {
-        "lastModified": 1754116698,
-        "narHash": "sha256-2cMDogXcqv975o191g0/6ZM0UolJ2X0ChuuLaNKbNAM=",
-        "owner": "nix-community",
-        "repo": "fenix",
-        "rev": "acdb7d8af407ea8aee21b028dc58b4bc51a7849a",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-community",
-        "repo": "fenix",
-        "type": "github"
-      }
-    },
     "flake-parts": {
       "inputs": {
         "nixpkgs-lib": "nixpkgs-lib"
@@ -54,16 +35,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1753939845,
-        "narHash": "sha256-K2ViRJfdVGE8tpJejs8Qpvvejks1+A4GQej/lBk5y7I=",
-        "owner": "nixos",
+        "lastModified": 1754060105,
+        "narHash": "sha256-di5L6e5Iiv+oegS07j9h23FdqEpXn0ZQqMlDOEMw1EY=",
+        "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "94def634a20494ee057c76998843c015909d6311",
+        "rev": "e7eabdc701d7dbb810fd91a97ec358caa4c1fc50",
         "type": "github"
       },
       "original": {
-        "owner": "nixos",
-        "ref": "nixos-unstable",
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
         "repo": "nixpkgs",
         "type": "github"
       }
@@ -85,11 +66,11 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1754060105,
-        "narHash": "sha256-di5L6e5Iiv+oegS07j9h23FdqEpXn0ZQqMlDOEMw1EY=",
+        "lastModified": 1744536153,
+        "narHash": "sha256-awS2zRgF4uTwrOKwwiJcByDzDOdo3Q1rPZbiHQg/N38=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "e7eabdc701d7dbb810fd91a97ec358caa4c1fc50",
+        "rev": "18dd725c29603f582cf1900e0d25f9f1063dbf11",
         "type": "github"
       },
       "original": {
@@ -102,25 +83,26 @@
     "root": {
       "inputs": {
         "crane": "crane",
-        "fenix": "fenix",
         "flake-parts": "flake-parts",
-        "nixpkgs": "nixpkgs_2"
+        "nixpkgs": "nixpkgs",
+        "rust-overlay": "rust-overlay"
       }
     },
-    "rust-analyzer-src": {
-      "flake": false,
+    "rust-overlay": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_2"
+      },
       "locked": {
-        "lastModified": 1753974682,
-        "narHash": "sha256-Ya4Ecj8JaKkapgYCCybzZBcypXpblhuG0hVDzdy2zyo=",
-        "owner": "rust-lang",
-        "repo": "rust-analyzer",
-        "rev": "68e7ec90bf29c9b17d0dcdb3358de5dee7f4afb5",
+        "lastModified": 1754966322,
+        "narHash": "sha256-7f/LH60DnjjQVKbXAsHIniGaU7ixVM7eWU3hyjT24YI=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "7c13cec2e3828d964b9980d0ffd680bd8d4dce90",
         "type": "github"
       },
       "original": {
-        "owner": "rust-lang",
-        "ref": "nightly",
-        "repo": "rust-analyzer",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
         "type": "github"
       }
     }

flake.nix

@@ -3,12 +3,12 @@
         nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
         crane.url = "github:ipetkov/crane";
         flake-parts.url = "github:hercules-ci/flake-parts";
-        fenix.url = "github:nix-community/fenix";
+        rust-overlay.url = "github:oxalica/rust-overlay";
     };
 
     outputs =
-        inputs@{ flake-parts, ... }:
-        flake-parts.lib.mkFlake { inherit inputs; } {
+        inputs:
+        inputs.flake-parts.lib.mkFlake { inherit inputs; } {
             systems = [
                 "aarch64-linux"
                 "aarch64-darwin"
@@ -17,19 +17,13 @@
             ];
 
             perSystem =
-                { pkgs, system, ... }:
+                { system, ... }:
                 let
-                    rustToolchain = inputs.fenix.packages.${system}.combine ([
-                        (inputs.fenix.packages.${system}.complete.withComponents [
-                            "cargo"
-                            "clippy"
-                            "rust-src"
-                            "rustc"
-                            "rustfmt"
-                        ])
-                        inputs.fenix.packages.${system}.complete.rust-analyzer
-                        inputs.fenix.packages.${system}.targets.wasm32-unknown-unknown.latest.rust-std
-                    ]);
+                    pkgs = import inputs.nixpkgs {
+                        inherit system;
+                        overlays = [ inputs.rust-overlay.overlays.default ];
+                    };
+                    rustToolchain = pkgs.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
                     craneLib = (inputs.crane.mkLib pkgs).overrideToolchain rustToolchain;
 
                     packages =
@@ -110,7 +104,6 @@
                     devShells.default = craneLib.devShell {
                         inputsFrom = [ vanth ];
                         packages = packages;
-                        RUST_SRC_PATH = "${rustToolchain}/lib/rustlib/src/rust/library";
                         LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath packages;
                     };
                 };

rust-toolchain.toml

@@ -0,0 +1,4 @@
+[toolchain]
+channel = "stable"
+components = ["cargo", "clippy", "rust-analyzer", "rust-src", "rustfmt"]
+targets = ["wasm32-unknown-unknown"]