{ lib
, stdenv
, mkMesonDerivation
, releaseTools

, meson
, ninja
, pkg-config
, bison
, flex
, cmake # for resolving toml11 dep

, nix-util
, nix-store
, nix-fetchers
, boost
, boehmgc
, nlohmann_json
, toml11

# Configuration Options

, versionSuffix ? ""

# Whether to use garbage collection for the Nix language evaluator.
#
# If it is disabled, we just leak memory, but this is not as bad as it
# sounds so long as evaluation just takes places within short-lived
# processes. (When the process exits, the memory is reclaimed; it is
# only leaked *within* the process.)
#
# Temporarily disabled on Windows because the `GC_throw_bad_alloc`
# symbol is missing during linking.
, enableGC ? !stdenv.hostPlatform.isWindows
}:

let
  inherit (lib) fileset;

  version = lib.fileContents ./.version + versionSuffix;
in

mkMesonDerivation (finalAttrs: {
  pname = "nix-expr";
  inherit version;

  workDir = ./.;
  fileset = fileset.unions [
    ../../build-utils-meson
    ./build-utils-meson
    ../../.version
    ./.version
    ./meson.build
    ./meson.options
    ./primops/meson.build
    (fileset.fileFilter (file: file.hasExt "cc") ./.)
    (fileset.fileFilter (file: file.hasExt "hh") ./.)
    ./lexer.l
    ./parser.y
    (fileset.fileFilter (file: file.hasExt "nix") ./.)
  ];

  outputs = [ "out" "dev" ];

  nativeBuildInputs = [
    meson
    ninja
    pkg-config
    bison
    flex
    cmake
  ];

  buildInputs = [
    toml11
  ];

  propagatedBuildInputs = [
    nix-util
    nix-store
    nix-fetchers
    boost
    nlohmann_json
  ] ++ lib.optional enableGC boehmgc;

  preConfigure =
    # "Inline" .version so it's not a symlink, and includes the suffix.
    # Do the meson utils, without modification.
    ''
      chmod u+w ./.version
      echo ${version} > ../../.version
    '';

  mesonFlags = [
    (lib.mesonEnable "gc" enableGC)
  ];

  env = {
    # Needed for Meson to find Boost.
    # https://github.com/NixOS/nixpkgs/issues/86131.
    BOOST_INCLUDEDIR = "${lib.getDev boost}/include";
    BOOST_LIBRARYDIR = "${lib.getLib boost}/lib";
  } // lib.optionalAttrs (stdenv.isLinux && !(stdenv.hostPlatform.isStatic && stdenv.system == "aarch64-linux")) {
    LDFLAGS = "-fuse-ld=gold";
  };

  enableParallelBuilding = true;

  separateDebugInfo = !stdenv.hostPlatform.isStatic;

  strictDeps = true;

  hardeningDisable = lib.optional stdenv.hostPlatform.isStatic "pie";

  meta = {
    platforms = lib.platforms.unix ++ lib.platforms.windows;
  };

})