feat(build): use crate2nix

flake.nix

@@ -7,6 +7,7 @@
       url = "github:oxalica/rust-overlay";
     };
     flake-utils.url = "github:numtide/flake-utils";
+    crate2nix.url = "github:nix-community/crate2nix";
   };
 
   outputs = {
@@ -14,6 +15,7 @@
     nixpkgs,
     rust-overlay,
     flake-utils,
+    crate2nix,
   }:
     flake-utils.lib.eachDefaultSystem (system: let
       overlays = [(import rust-overlay)];
@@ -24,6 +26,25 @@
         extensions = ["rust-src" "clippy" "rustfmt"];
         targets = pkgs.lib.optionals isLinux ["x86_64-unknown-linux-musl"];
       };
+
+      buildPkgs =
+        if isLinux
+        then pkgs.pkgsMusl
+        else pkgs;
+
+      generatedCargoNix = crate2nix.tools.${system}.generatedCargoNix {
+        name = "improvise";
+        src = ./.;
+      };
+
+      cargoNix = import generatedCargoNix {
+        inherit pkgs;
+        buildRustCrateForPkgs = pkgs:
+          buildPkgs.buildRustCrate.override {
+            rustc = rustToolchain;
+            cargo = rustToolchain;
+          };
+      };
     in {
       devShells.default = pkgs.mkShell ({
           nativeBuildInputs =
@@ -31,48 +52,21 @@
               rustToolchain
               pkgs.pkg-config
               pkgs.rust-analyzer
+              crate2nix.packages.${system}.default
             ]
             ++ pkgs.lib.optionals isLinux [
-              # Provide cc (gcc) for building proc-macro / build-script crates
-              # that target the host (x86_64-unknown-linux-gnu).
               pkgs.gcc
-              # musl-gcc wrapper for the static musl target.
               pkgs.pkgsMusl.stdenv.cc
             ];
 
           RUST_BACKTRACE = "1";
         }
         // pkgs.lib.optionalAttrs isLinux {
-          # Tell Cargo which linker to use for each target so it never
-          # falls back to rust-lld (which can't find glibc on NixOS).
           CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER = "${pkgs.gcc}/bin/gcc";
           CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER = "${pkgs.pkgsMusl.stdenv.cc}/bin/cc";
-
-          # Default build target: static musl binary.
           CARGO_BUILD_TARGET = "x86_64-unknown-linux-musl";
         });
 
-      packages.default =
-        if isLinux
-        then
-          (pkgs.pkgsMusl.makeRustPlatform {
-            cargo = rustToolchain;
-            rustc = rustToolchain;
-          }).buildRustPackage {
-            pname = "improvise";
-            version = "0.1.0";
-            src = ./.;
-            cargoLock.lockFile = ./Cargo.lock;
-          }
-        else
-          (pkgs.makeRustPlatform {
-            cargo = rustToolchain;
-            rustc = rustToolchain;
-          }).buildRustPackage {
-            pname = "improvise";
-            version = "0.1.0";
-            src = ./.;
-            cargoLock.lockFile = ./Cargo.lock;
-          };
+      packages.default = cargoNix.rootCrate.build;
     });
 }