Add initial version of the flake module

README.md

@@ -1,2 +1,10 @@
 # rust-flake
+
 WIP: Like the famous `haskell-flake`, but for Rust.
+
+## Progress
+
+- [x] Simple module that works with single-create projects
+- [ ] Multi-crate workspaces
+- [ ] Multiple projects
+- [ ] Examples & tests

flake.nix

@@ -0,0 +1,16 @@
+{
+  description = "A `flake-parts` module for Rust development";
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    rust-overlay.url = "github:oxalica/rust-overlay";
+    # https://github.com/ipetkov/crane/issues/527
+    crane.url = "github:ipetkov/crane/2c653e4478476a52c6aa3ac0495e4dea7449ea0e"; # Cargo.toml parsing is broken in newer crane (Mar 24)
+    crane.inputs.nixpkgs.follows = "nixpkgs";
+  };
+  outputs = { rust-overlay, crane, ... }: {
+    flakeModules = {
+      default = import ./nix/modules/flake-module.nix { inherit rust-overlay crane; };
+      nixpkgs = import ./nix/modules/nixpkgs.nix;
+    };
+  };
+}

nix/modules/flake-module.nix

@@ -0,0 +1,124 @@
+inputs:
+{ self, lib, flake-parts-lib, ... }:
+
+let
+  inherit (flake-parts-lib)
+    mkPerSystemOption;
+in
+{
+  options = {
+    perSystem = mkPerSystemOption
+      ({ config, self', pkgs, system, ... }: {
+        options = {
+          # TODO: Multiple projects
+          # TODO: Workspace crates
+          rust-project.crane.args.buildInputs = lib.mkOption {
+            type = lib.types.listOf lib.types.package;
+            default = [ ];
+            description = "(Runtime) buildInputs for the cargo package";
+          };
+          rust-project.crane.args.nativeBuildInputs = lib.mkOption {
+            type = lib.types.listOf lib.types.package;
+            default = with pkgs; [
+              pkg-config
+              makeWrapper
+            ];
+            description = "nativeBuildInputs for the cargo package";
+          };
+          rust-project.crane.lib = lib.mkOption {
+            type = lib.types.lazyAttrsOf lib.types.raw;
+            default = (inputs.crane.mkLib pkgs).overrideToolchain config.rust-project.toolchain;
+          };
+
+          rust-project.toolchain = lib.mkOption {
+            type = lib.types.package;
+            description = "Rust toolchain to use for the rust-project package";
+            default = (pkgs.rust-bin.fromRustupToolchainFile (self + /rust-toolchain.toml)).override {
+              extensions = [
+                "rust-src"
+                "rust-analyzer"
+                "clippy"
+              ];
+            };
+          };
+
+          rust-project.src = lib.mkOption {
+            type = lib.types.path;
+            description = "Source directory for the rust-project package";
+            default = lib.cleanSourceWith {
+              src = self; # The original, unfiltered source
+              filter = path: type:
+                # Default filter from crane (allow .rs files)
+                (config.rust-project.crane.lib.filterCargoSources path type)
+              ;
+            };
+          };
+        };
+        config =
+          let
+            cargoToml = builtins.fromTOML (builtins.readFile (self + /Cargo.toml));
+            inherit (cargoToml.package) name version;
+            inherit (config.rust-project) toolchain crane src;
+
+            # Crane builder
+            craneBuild = rec {
+              args = {
+                inherit src;
+                inherit (crane.args) buildInputs nativeBuildInputs;
+                pname = name;
+                version = version;
+                # glib-sys fails to build on linux without this
+                # cf. https://github.com/ipetkov/crane/issues/411#issuecomment-1747533532
+                strictDeps = true;
+              };
+              cargoArtifacts = crane.lib.buildDepsOnly args;
+              buildArgs = args // {
+                inherit cargoArtifacts;
+              };
+              package = crane.lib.buildPackage buildArgs;
+
+              check = crane.lib.cargoClippy (args // {
+                inherit cargoArtifacts;
+                cargoClippyExtraArgs = "--all-targets --all-features -- --deny warnings";
+              });
+
+              doc = crane.lib.cargoDoc (args // {
+                inherit cargoArtifacts;
+              });
+            };
+
+            rustDevShell = pkgs.mkShell {
+              shellHook = ''
+                # For rust-analyzer 'hover' tooltips to work.
+                export RUST_SRC_PATH="${toolchain}/lib/rustlib/src/rust/library";
+              '';
+              buildInputs = [
+                pkgs.libiconv
+              ] ++ config.rust-project.crane.args.buildInputs;
+              packages = [
+                toolchain
+              ];
+            };
+          in
+          {
+            # See nix/modules/nixpkgs.nix (the user must import it)
+            nixpkgs.overlays = [
+              inputs.rust-overlay.overlays.default
+            ];
+
+            # Rust package
+            packages.${name} = craneBuild.package;
+            packages."${name}-doc" = craneBuild.doc;
+
+            checks."${name}-clippy" = craneBuild.check;
+
+            # Rust dev environment
+            devShells.${name} = pkgs.mkShell {
+              inputsFrom = [
+                rustDevShell
+              ];
+            };
+          };
+      });
+  };
+}

nix/modules/nixpkgs.nix

@@ -0,0 +1,9 @@
+# https://github.com/hercules-ci/flake-parts/issues/74#issuecomment-1513708722
+{ inputs, flake-parts-lib, ... }: {
+  options.perSystem = flake-parts-lib.mkPerSystemOption ({ pkgs, system, ... }: {
+    imports = [
+      "${inputs.nixpkgs}/nixos/modules/misc/nixpkgs.nix"
+    ];
+    nixpkgs.hostPlatform = system;
+  });
+}