flake.nix: update rustc

flake.lock

@@ -55,7 +55,41 @@
         "type": "github"
       }
     },
+    "flake-utils_2": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1694529238,
+        "narHash": "sha256-zsNZZGTGnMOf9YpHKJqMSsa0dXbfmxeoJ7xHlrt+xmY=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "ff7b65b44d01cf9ba6a71320833626af21126384",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
+      "locked": {
+        "lastModified": 1696234590,
+        "narHash": "sha256-mgOzQYTvaTT4bFopVOadlndy2RPwLy60rDjIWOGujwo=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "f902cb49892d300ff15cb237e48aa1cad79d68c3",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
       "locked": {
         "lastModified": 1665657542,
         "narHash": "sha256-mojxNyzbvmp8NtVtxqiHGhRfjCALLfk9i/Uup68Y5q8=",
@@ -74,26 +108,20 @@
     "root": {
       "inputs": {
         "cargo2nix": "cargo2nix",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs_2"
       }
     },
     "rust-overlay": {
       "inputs": {
-        "flake-utils": [
-          "cargo2nix",
-          "flake-utils"
-        ],
-        "nixpkgs": [
-          "cargo2nix",
-          "nixpkgs"
-        ]
+        "flake-utils": "flake-utils_2",
+        "nixpkgs": "nixpkgs"
       },
       "locked": {
-        "lastModified": 1664247556,
-        "narHash": "sha256-J4vazHU3609ekn7dr+3wfqPo5WGlZVAgV7jfux352L0=",
+        "lastModified": 1682389182,
+        "narHash": "sha256-8t2nmFnH+8V48+IJsf8AK51ebXNlVbOSVYOpiqJKvJE=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "524db9c9ea7bc7743bb74cdd45b6d46ea3fcc2ab",
+        "rev": "74f1a64dd28faeeb85ef081f32cad2989850322c",
         "type": "github"
       },
       "original": {
@@ -101,6 +129,21 @@
         "repo": "rust-overlay",
         "type": "github"
       }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
     }
   },
   "root": "root",

flake.nix

@@ -5,6 +5,11 @@
   inputs.cargo2nix = {
     # As of 2022-10-18: two small patches over unstable branch, one for clippy and one to fix feature detection
     url = "github:Alexis211/cargo2nix/a7a61179b66054904ef6a195d8da736eaaa06c36";
+
+    # Rust overlay as of 2023-04-25
+    inputs.rust-overlay.url =
+      "github:oxalica/rust-overlay/74f1a64dd28faeeb85ef081f32cad2989850322c";
+
     inputs.nixpkgs.follows = "nixpkgs";
   };
 
@@ -15,7 +20,7 @@
       overlays = [ cargo2nix.overlays.default ];
     };
     packageFun = import ./Cargo.nix;
-    rustVersion = "1.63.0";
+    rustVersion = "1.68.0";
 
     compile = args: compileMode:
       let