drop rust-overlay, use rustc from nixpkgs

nixpkgs has a recent enough rustc version, no need for the
extra complexity of rust-overlay and rust-toolchain.toml.

flake.lock

@@ -39,28 +39,7 @@
     "root": {
       "inputs": {
         "flake-parts": "flake-parts",
-        "nixpkgs": "nixpkgs",
-        "rust-overlay": "rust-overlay"
-      }
-    },
-    "rust-overlay": {
-      "inputs": {
-        "nixpkgs": [
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1763087910,
-        "narHash": "sha256-eB9Z1mWd1U6N61+F8qwDggX0ihM55s4E0CluwNukJRU=",
-        "owner": "oxalica",
-        "repo": "rust-overlay",
-        "rev": "cf4a68749733d45c0420726596367acd708eb2e8",
-        "type": "github"
-      },
-      "original": {
-        "owner": "oxalica",
-        "repo": "rust-overlay",
-        "type": "github"
+        "nixpkgs": "nixpkgs"
       }
     }
   },

flake.nix

@@ -3,10 +3,6 @@
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-parts.url = "github:hercules-ci/flake-parts";
     flake-parts.inputs.nixpkgs-lib.follows = "nixpkgs";
-    rust-overlay = {
-      url = "github:oxalica/rust-overlay";
-      inputs.nixpkgs.follows = "nixpkgs";
-    };
   };
 
   outputs =
@@ -18,35 +14,20 @@
       ];
 
       perSystem =
-        {
-          pkgs,
-          system,
-          ...
-        }:
+        { pkgs, ... }:
         let
-          overlays = [ (import inputs.rust-overlay) ];
-          pkgs' = import inputs.nixpkgs {
-            inherit system overlays;
-          };
-
           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";
           };
 
-          rustToolchain = pkgs'.pkgsBuildHost.rust-bin.fromRustupToolchainFile ./rust-toolchain.toml;
-          rustPlatform = pkgs'.makeRustPlatform {
-            cargo = rustToolchain;
-            rustc = rustToolchain;
-          };
-
           rustPackage =
             crate:
             let
               cargoToml = builtins.fromTOML (builtins.readFile ./${crate}/Cargo.toml);
             in
-            rustPlatform.buildRustPackage {
+            pkgs.rustPlatform.buildRustPackage {
               inherit (cargoToml.package) name version;
               src = ./.;
               cargoLock.lockFile = ./Cargo.lock;
@@ -59,8 +40,13 @@
             };
         in
         {
-          devShells.default = pkgs'.mkShell {
-            buildInputs = [ rustToolchain ];
+          devShells.default = pkgs.mkShell {
+            buildInputs = with pkgs; [
+              cargo
+              rustc
+              rust-analyzer
+              clippy
+            ];
             env = buildEnvVars;
           };
 

rust-toolchain.toml

@@ -1,3 +0,0 @@
-[toolchain]
-channel = "1.88.0"
-components = ["rust-analyzer", "rust-src", "clippy"]