flake.nix

{
  description = "Build a cargo project";

  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";

    crane = {
      url = "github:ipetkov/crane";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    fenix = {
      url = "github:nix-community/fenix";
      inputs.nixpkgs.follows = "nixpkgs";
    };

    flake-utils.url = "github:numtide/flake-utils";

    advisory-db = {
      url = "github:rustsec/advisory-db";
      flake = false;
    };
  };

  outputs = {
    self,
    nixpkgs,
    crane,
    fenix,
    flake-utils,
    advisory-db,
    ...
  }:
    flake-utils.lib.eachDefaultSystem (system: let
      pkgs = import nixpkgs {
        inherit system;
        overlays = [fenix.overlays.default];
      };

      inherit (pkgs) lib;

      craneLib = crane.lib.${system};
      src = craneLib.cleanCargoSource (craneLib.path ./.);

      # Common arguments can be set here to avoid repeating them later
      commonArgs = {
        inherit src;
        strictDeps = true;

        buildInputs =
          [
            # Add additional build inputs here
          ]
          ++ lib.optionals pkgs.stdenv.isDarwin [
            # Additional darwin specific inputs can be set here
            pkgs.libiconv
          ];

        # Additional environment variables can be set directly
        # MY_CUSTOM_VAR = "some value";
        RUST_SRC_PATH = "${pkgs.fenix.complete.rust-src}/lib/rustlib/src/rust/library";
      };

      toolchain = pkgs.fenix.complete.withComponents [
        "clippy"
        "rust-src"
        "cargo"
        "rustc"
        "rustfmt"
      ];

      craneLibLLvmTools = craneLib.overrideToolchain toolchain;

      # Build *just* the cargo dependencies, so we can reuse
      # all of that work (e.g. via cachix) when running in CI
      cargoArtifacts = craneLib.buildDepsOnly commonArgs;

      # Build the actual crate itself, reusing the dependency
      # artifacts from above.
      my-crate = craneLib.buildPackage (commonArgs
        // {
          inherit cargoArtifacts;
        });
    in {
      checks = {
        # Build the crate as part of `nix flake check` for convenience
        inherit my-crate;

        # Run clippy (and deny all warnings) on the crate source,
        # again, resuing the dependency artifacts from above.
        #
        # Note that this is done as a separate derivation so that
        # we can block the CI if there are issues here, but not
        # prevent downstream consumers from building our crate by itself.
        my-crate-clippy = craneLib.cargoClippy (commonArgs
          // {
            inherit cargoArtifacts;
            cargoClippyExtraArgs = "--all-targets -- --deny warnings";
          });

        my-crate-doc = craneLib.cargoDoc (commonArgs
          // {
            inherit cargoArtifacts;
          });

        # Check formatting
        my-crate-fmt = craneLib.cargoFmt {
          inherit src;
        };

        # Audit dependencies
        my-crate-audit = craneLib.cargoAudit {
          inherit src advisory-db;
        };

        # Audit licenses
        my-crate-deny = craneLib.cargoDeny {
          inherit src;
        };

        # Run tests with cargo-nextest
        # Consider setting `doCheck = false` on `my-crate` if you do not want
        # the tests to run twice
        my-crate-nextest = craneLib.cargoNextest (commonArgs
          // {
            inherit cargoArtifacts;
            partitions = 1;
            partitionType = "count";
          });
      };

      packages = {
        default = my-crate;
        my-crate-llvm-coverage = craneLibLLvmTools.cargoLlvmCov (commonArgs
          // {
            inherit cargoArtifacts;
          });
      };

      apps.default = flake-utils.lib.mkApp {
        drv = my-crate;
      };

      devShells.default = craneLib.devShell {
        # Inherit inputs from checks.
        checks = self.checks.${system};

        RUST_SRC_PATH = "${pkgs.fenix.complete.rust-src}/lib/rustlib/src/rust/library";

        # Extra inputs can be added here; cargo and rustc are provided by default.
        packages = [
          toolchain
          pkgs.rust-analyzer-nightly
          pkgs.pkg-config
          pkgs.alejandra
          pkgs.nil
          pkgs.cargo-shuttle
          pkgs.bacon
          pkgs.marksman
        ];
      };
    });
}