build(nix): change rust overlay to use nightly

flake.lock

@@ -15,13 +15,28 @@
         "type": "github"
       }
     },
+    "flake-utils_2": {
+      "locked": {
+        "lastModified": 1656928814,
+        "narHash": "sha256-RIFfgBuKz6Hp89yRr7+NR5tzIAbn52h8vT6vXkYjZoM=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "7e2a3b3dfd9af950a856d66b0a7d01e3c18aa249",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1663494472,
-        "narHash": "sha256-fSowlaoXXWcAM8m9wA6u+eTJJtvruYHMA+Lb/tFi/qM=",
+        "lastModified": 1663761423,
+        "narHash": "sha256-bDLXl2BVq7eIQz/8CduZI1SLyhG9u/CrckHd6f7bwPE=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "f677051b8dc0b5e2a9348941c99eea8c4b0ff28f",
+        "rev": "d6490a0bd9dfb298fcd8382d3363b86870dc7340",
         "type": "github"
       },
       "original": {
@@ -33,7 +48,29 @@
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs",
+        "rust-overlay": "rust-overlay"
+      }
+    },
+    "rust-overlay": {
+      "inputs": {
+        "flake-utils": "flake-utils_2",
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1663815552,
+        "narHash": "sha256-J4j/d69SGKx1qripBCINe7T3SUtMM1sdj5PoHRThV5Q=",
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "rev": "f45f856ae5a9fe2c48d756fa17bb9c5b3b8070c5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "oxalica",
+        "repo": "rust-overlay",
+        "type": "github"
       }
     }
   },

flake.nix

@@ -2,16 +2,26 @@
   inputs = {
     flake-utils.url = "github:numtide/flake-utils";
     nixpkgs.url = "nixpkgs/nixos-unstable";
+
+    rust-overlay.url = "github:oxalica/rust-overlay";
+    rust-overlay.inputs.nixpkgs.follows = "nixpkgs";
   };
 
-  outputs = { self, flake-utils, nixpkgs }:
+  outputs = { self, flake-utils, rust-overlay, nixpkgs }:
     flake-utils.lib.eachDefaultSystem (system:
-      let pkgs = nixpkgs.legacyPackages.${system};
+      let
+        rustPackages = pkgs.rust-bin.nightly.latest;
+        pkgs = import nixpkgs {
+          inherit system;
+          overlays = [ (import rust-overlay) ];
+        };
       in rec {
         packages.default = pkgs.rustPlatform.buildRustPackage {
           pname = "proost";
           version = "0.1.0";
 
+          nativeBuildInputs = [ rustPackages.default ];
+
           src = ./.;
           cargoLock.lockFile = ./Cargo.lock;
 
@@ -25,7 +35,7 @@
         devShells.default = pkgs.mkShell {
           name = "proost-dev";
           packages = packages.default.nativeBuildInputs
-            ++ (with pkgs; [ rustfmt clippy ]);
+            ++ (with rustPackages; [ rustfmt clippy ]);
         };
       });
 }