Fix nixpkgs duplication

Reuse nixpkgs input in rust-overlay.

flake.lock

@@ -34,22 +34,6 @@
         "type": "github"
       }
     },
-    "nixpkgs_2": {
-      "locked": {
-        "lastModified": 1744536153,
-        "narHash": "sha256-awS2zRgF4uTwrOKwwiJcByDzDOdo3Q1rPZbiHQg/N38=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "18dd725c29603f582cf1900e0d25f9f1063dbf11",
-        "type": "github"
-      },
-      "original": {
-        "owner": "NixOS",
-        "ref": "nixpkgs-unstable",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
@@ -59,7 +43,9 @@
     },
     "rust-overlay": {
       "inputs": {
-        "nixpkgs": "nixpkgs_2"
+        "nixpkgs": [
+          "nixpkgs"
+        ]
       },
       "locked": {
         "lastModified": 1746239644,

flake.nix

@@ -2,7 +2,10 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
     flake-utils.url = "github:numtide/flake-utils";
-    rust-overlay.url = "github:oxalica/rust-overlay";
+    rust-overlay = {
+      url = "github:oxalica/rust-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
   outputs = { self, nixpkgs, flake-utils, rust-overlay }:
     flake-utils.lib.eachDefaultSystem