little-hesinde/flake.nix

{
  description = "rusty-library project";
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
    flake-utils.url = "github:numtide/flake-utils";
    naersk.url = "github:nix-community/naersk";
    fenix.url = "github:nix-community/fenix";
  };

  outputs =
    {
      nixpkgs,
      naersk,
      fenix,
      flake-utils,
      ...
    }:
    let
      buildTargets = {
        "x86_64-linux" = {
          crossSystemConfig = "x86_64-unknown-linux-musl";
          rustTarget = "x86_64-unknown-linux-musl";
        };

        "i686-linux" = {
          crossSystemConfig = "i686-unknown-linux-musl";
          rustTarget = "i686-unknown-linux-musl";
        };

        "aarch64-linux" = {
          crossSystemConfig = "aarch64-unknown-linux-musl";
          rustTarget = "aarch64-unknown-linux-musl";
        };

        "armv6l-linux" = {
          crossSystemConfig = "armv6l-unknown-linux-musleabihf";
          rustTarget = "arm-unknown-linux-musleabihf";
        };
      };

      eachSystem =
        supportedSystems: callback:
        builtins.foldl' (overall: system: overall // { ${system} = callback system; }) { } supportedSystems;

      eachCrossSystem =
        supportedSystems: callback:
        eachSystem supportedSystems (
          buildSystem:
          builtins.foldl' (
            inner: targetSystem: inner // { "cross-${targetSystem}" = callback buildSystem targetSystem; }
          ) { default = callback buildSystem buildSystem; } supportedSystems
        );

      mkPkgs =
        buildSystem: targetSystem:
        import nixpkgs (
          {
            system = buildSystem;
          }
          // (
            if targetSystem == null then
              { }
            else
              { crossSystem.config = buildTargets.${targetSystem}.crossSystemConfig; }
          )
        );
    in
    flake-utils.lib.eachDefaultSystem (
      system:
      let
        pkgs = import nixpkgs { inherit system; };
        rust = fenix.packages.${system}.stable;
      in
      {
        devShells.default = pkgs.mkShell {
          buildInputs = [
            rust.toolchain
            pkgs.cargo-deny
            pkgs.rust-analyzer
          ];
        };
      }
    )
    // {
      packages = eachCrossSystem (builtins.attrNames buildTargets) (
        buildSystem: targetSystem:
        let
          pkgs = mkPkgs buildSystem null;
          pkgsCross = mkPkgs buildSystem targetSystem;
          rustTarget = buildTargets.${targetSystem}.rustTarget;

          fenixPkgs = fenix.packages.${buildSystem};

          mkToolchain = fenixPkgs: fenixPkgs.stable;

          toolchain = fenixPkgs.combine [
            (mkToolchain fenixPkgs).rustc
            (mkToolchain fenixPkgs).cargo
            (mkToolchain fenixPkgs.targets.${rustTarget}).rust-std
          ];

          buildPackageAttrs =
            if builtins.hasAttr "makeBuildPackageAttrs" buildTargets.${targetSystem} then
              buildTargets.${targetSystem}.makeBuildPackageAttrs pkgsCross
            else
              { };

          naersk-lib = pkgs.callPackage naersk {
            cargo = toolchain;
            rustc = toolchain;
          };
        in
        naersk-lib.buildPackage (
          buildPackageAttrs
          // rec {
            src = ./.;
            strictDeps = true;
            doCheck = true;
            nativeBuildInputs = [ pkgs.cargo-deny ];
            cargoTestCommands = (default: default ++ [ "cargo deny check ban bans license licenses sources" ]);

            TARGET_CC = "${pkgsCross.stdenv.cc}/bin/${pkgsCross.stdenv.cc.targetPrefix}cc";

            CARGO_BUILD_TARGET = rustTarget;
            CARGO_BUILD_RUSTFLAGS = [
              "-C"
              "target-feature=+crt-static"

              "-C"
              "linker=${TARGET_CC}"
            ];
          }
        )
      );
    };
}