fix: update toolchain in nix (amber-lang#307)

Cargo.toml

@@ -3,6 +3,7 @@ name = "amber"
 version = "0.3.4-alpha"
 edition = "2021"
 repository = "https://github.com/Ph0enixKM/Amber"
+rust-version = "1.79"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

flake.nix

@@ -3,27 +3,58 @@
     naersk.url = "github:nix-community/naersk/master";
     nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
     utils.url = "github:numtide/flake-utils";
+    nixpkgs-mozilla = {
+      url = "github:mozilla/nixpkgs-mozilla";
+      flake = false;
+    };
   };
 
-  outputs = { self, nixpkgs, utils, naersk }:
-    utils.lib.eachDefaultSystem (system:
+  outputs =
+    {
+      self,
+      nixpkgs,
+      utils,
+      naersk,
+      nixpkgs-mozilla,
+    }:
+    utils.lib.eachDefaultSystem (
+      system:
       let
-        pkgs = import nixpkgs { inherit system; };
-        naersk-lib = pkgs.callPackage naersk { };
+        pkgs = import nixpkgs {
+          inherit system;
+          overlays = [ (import nixpkgs-mozilla) ];
+        };
+        toolchain =
+          (pkgs.rustChannelOf {
+            rustToolchain = ./rust-toolchain.toml;
+            sha256 = "sha256-Ngiz76YP4HTY75GGdH2P+APE/DEIx2R/Dn+BwwOyzZU=";
+          }).rust;
+        naersk-lib = pkgs.callPackage naersk {
+          cargo = toolchain;
+          rustc = toolchain;
+        };
       in
       {
         packages.default = naersk-lib.buildPackage {
           src = ./.;
           postInstall = ''
-            wrapProgram "$out/bin/amber" --set PATH ${nixpkgs.lib.makeBinPath [
-              pkgs.bc
-            ]}
+            wrapProgram "$out/bin/amber" --set PATH ${nixpkgs.lib.makeBinPath [ pkgs.bc ]}
           '';
         };
-        devShells.default = with pkgs; mkShell {
-          buildInputs = [ bc cargo rustc rustfmt pre-commit rustPackages.clippy ];
-          RUST_SRC_PATH = rustPlatform.rustLibSrc;
-        };
+        devShells.default =
+          with pkgs;
+          mkShell {
+            buildInputs = [
+              bc
+              cargo
+              rustc
+              rustfmt
+              pre-commit
+              rustPackages.clippy
+            ];
+            nativeBuildInputs = [ toolchain ];
+            RUST_SRC_PATH = rustPlatform.rustLibSrc;
+          };
       }
     );
 }

rust-toolchain.toml

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "stable"
+components = ["rustfmt", "clippy", "rust-src"]