--- flake.nix	2022-10-19 11:10:47.604364787 -0700
+++ fixed.nix	2022-10-19 11:11:14.429945027 -0700
@@ -25,15 +25,14 @@
             channel = "nightly";
             date = "2022-10-19";
             sha256 = "wqcIBI0cuNAj3g4Fpk83jajPpwlyV4EetYex1vInAFY=";
-          }).toolchain;
+          });


           pkgs = nixpkgs.legacyPackages.${system};
         in

         (pkgs.makeRustPlatform {
-          cargo = toolchain;
-          rustc = toolchain;
+          inherit (toolchain) cargo rustc;
         }).buildRustPackage {
           pname = "uad";
           version = "0.5.1";

one other change i would recommend as well:

--- flake.nix	2022-10-19 11:10:47.604364787 -0700
+++ fixed.nix	2022-10-19 11:19:38.387891737 -0700
@@ -39,6 +39,8 @@
           version = "0.5.1";

           src = uad;
+
+          cargoLock.lockFile = "${uad}/Cargo.lock";

 #          src = pkgs.fetchFromGitHub {
 #            owner = "0x192";
@@ -46,7 +48,6 @@
 #            rev = "0.5.1";
 #            sha256 = "0ByB/jRJze9B2o4S1nevy+uIvEpjMszAVB0pB6WWocU=";
 #          };
-  cargoSha256 = "D2PsUoL1v9RWV1GNGHVQWvrY8I/hNaGvSZSsQJSh08w=";

         };
     });

makes it less annoying to pull updates

❯ nix build .#
error: No hash was found while vendoring the git dependency glutin-0.28.0. You can add
       a hash through the `outputHashes` argument of `importCargoLock`:

       outputHashes = {
         "glutin-0.28.0" = "<hash>";
       };

       If you use `buildRustPackage`, you can add this attribute to the `cargoLock`
       attribute set.
(use '--show-trace' to show detailed location information)