add rust support into nix flake

flake.lock

@@ -1,5 +1,26 @@
 {
   "nodes": {
+    "fenix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "rust-analyzer-src": "rust-analyzer-src"
+      },
+      "locked": {
+        "lastModified": 1763016383,
+        "narHash": "sha256-eYmo7FNvm3q08iROzwIi8i9dWuUbJJl3uLR3OLnSmdI=",
+        "owner": "nix-community",
+        "repo": "fenix",
+        "rev": "0fad5c0e5c531358e7174cd666af4608f08bc3ba",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "fenix",
+        "type": "github"
+      }
+    },
     "flake-compat": {
       "flake": false,
       "locked": {
@@ -75,11 +96,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1756822655,
-        "narHash": "sha256-xQAk8xLy7srAkR5NMZFsQFioL02iTHuuEIs3ohGpgdk=",
+        "lastModified": 1763043403,
+        "narHash": "sha256-DgCTbHdIpzbXSlQlOZEWj8oPt2lrRMlSk03oIstvkVQ=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "4bdac60bfe32c41103ae500ddf894c258291dd61",
+        "rev": "75e04ecd084f93d4105ce68c07dac7656291fe2e",
         "type": "github"
       },
       "original": {
@@ -91,12 +112,30 @@
     },
     "root": {
       "inputs": {
+        "fenix": "fenix",
         "flake-utils": "flake-utils",
         "nixpkgs": "nixpkgs",
         "zigPkgs": "zigPkgs",
         "zlsPkg": "zlsPkg"
       }
     },
+    "rust-analyzer-src": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1762860488,
+        "narHash": "sha256-rMfWMCOo/pPefM2We0iMBLi2kLBAnYoB9thi4qS7uk4=",
+        "owner": "rust-lang",
+        "repo": "rust-analyzer",
+        "rev": "2efc80078029894eec0699f62ec8d5c1a56af763",
+        "type": "github"
+      },
+      "original": {
+        "owner": "rust-lang",
+        "ref": "nightly",
+        "repo": "rust-analyzer",
+        "type": "github"
+      }
+    },
     "systems": {
       "locked": {
         "lastModified": 1681028828,
@@ -136,11 +175,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1756555914,
-        "narHash": "sha256-7yoSPIVEuL+3Wzf6e7NHuW3zmruHizRrYhGerjRHTLI=",
+        "lastModified": 1762907712,
+        "narHash": "sha256-VNW/+VYIg6N4b9Iq+F0YZmm22n74IdFS7hsPLblWuOY=",
         "owner": "mitchellh",
         "repo": "zig-overlay",
-        "rev": "d0df3a2fd0f11134409d6d5ea0e510e5e477f7d6",
+        "rev": "d16453ee78765e49527c56d23386cead799b6b53",
         "type": "github"
       },
       "original": {

flake.nix

@@ -11,6 +11,11 @@
     zlsPkg.inputs.zig-overlay.follows = "zigPkgs";
     zlsPkg.inputs.nixpkgs.follows = "nixpkgs";
 
+    fenix = {
+      url = "github:nix-community/fenix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
+
     flake-utils.url = "github:numtide/flake-utils";
   };
 
@@ -19,6 +24,7 @@
       nixpkgs,
       zigPkgs,
       zlsPkg,
+      fenix,
       flake-utils,
       ...
     }:
@@ -36,6 +42,8 @@
           inherit system overlays;
         };
 
+        rustToolchain = fenix.packages.${system}.stable.toolchain;
+
         # We need crtbeginS.o for building.
         crtFiles = pkgs.runCommand "crt-files" { } ''
           mkdir -p $out/lib
@@ -51,6 +59,7 @@
               # Build Tools
               zigpkgs."0.15.2"
               zls
+              rustToolchain
               python3
               pkg-config
               cmake
@@ -66,7 +75,6 @@
               glib.dev
               glibc.dev
               zlib
-              zlib.dev
             ];
         };
       in