use oxalica's rust-overlay

flake.lock

@@ -37,7 +37,31 @@
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs",
+        "rust-overlay": "rust-overlay"
+      }
+    },
+    "rust-overlay": {
+      "inputs": {
+        "flake-utils": [
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1702088052,
+        "narHash": "sha256-FkwIBTAMsxyceQce0Mbm+/+cOjj2r5IHBK4R/ekPNaw=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "2cfb76b8e836a26efecd9f853bea78355a11c58a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
       }
     },
     "systems": {

flake.nix

@@ -4,12 +4,20 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
     flake-utils.url = "github:numtide/flake-utils";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs = {
+        nixpkgs.follows = "nixpkgs";
+        flake-utils.follows = "flake-utils";
+      };
+    };
   };
 
-  outputs = { self, nixpkgs, flake-utils }: flake-utils.lib.eachDefaultSystem (system:
+  outputs = { self, nixpkgs, flake-utils, rust-overlay }: flake-utils.lib.eachDefaultSystem (system:
     let
       pkgs = import nixpkgs {
         inherit system;
+        overlays = [ rust-overlay.overlays.default ];
       };
     in
     {

shells/rust.nix

@@ -1,5 +1,7 @@
 { pkgs }: pkgs.mkShell {
-  packages = with pkgs; [ cargo rustc rustfmt rust-analyzer ];
+  buildInputs = with pkgs; [
+    (rust-bin.stable.latest.default.override { extensions = [ "rust-src" "rust-analyzer" ]; })
+  ];
   shellHook = ''
     export CARGO_HOME=$PWD/.nix/cargo
     export PATH=$CARGO_HOME/bin:$PATH