{ system, name ? "stdenv", preHook ? "", initialPath, gcc, shell
, extraAttrs ? {}, overrides ? (pkgs: {}), config

, # The `fetchurl' to use for downloading curl and its dependencies
  # (see all-packages.nix).
  fetchurlBoot
}:

if ! builtins ? langVersion then

  abort "This version of Nixpkgs requires Nix >= 1.2, please upgrade!"

else

let

  lib = import ../../../lib;

  allowUnfree = config.allowUnfree or true && builtins.getEnv "HYDRA_DISALLOW_UNFREE" != "1";

  stdenvGenerator = setupScript: rec {

    # The stdenv that we are producing.
    result =

      derivation {
        inherit system name;

        builder = shell;

        args = ["-e" ./builder.sh];

        setup = setupScript;

        inherit preHook initialPath gcc shell;

        propagatedUserEnvPkgs = [gcc] ++
          lib.filter lib.isDerivation initialPath;

        __ignoreNulls = true;
      }

      // rec {

        meta = {
          description = "The default build environment for Unix packages in Nixpkgs";
        };

        # Add a utility function to produce derivations that use this
        # stdenv and its shell.
        mkDerivation = attrs:
          if !allowUnfree && (let l = attrs.meta.license or ""; in l == "unfree" || l == "unfree-redistributable") then
            throw "package ‘${attrs.name}’ has an unfree license, refusing to evaluate"
          else
            lib.addPassthru (derivation (
              (removeAttrs attrs ["meta" "passthru" "crossAttrs"])
              // (let
                buildInputs = attrs.buildInputs or [];
                nativeBuildInputs = attrs.nativeBuildInputs or [];
                propagatedBuildInputs = attrs.propagatedBuildInputs or [];
                propagatedNativeBuildInputs = attrs.propagatedNativeBuildInputs or [];
                crossConfig = attrs.crossConfig or null;
              in
              {
                builder = attrs.realBuilder or shell;
                args = attrs.args or ["-e" (attrs.builder or ./default-builder.sh)];
                stdenv = result;
                system = result.system;
                userHook = config.stdenv.userHook or null;

                # Inputs built by the cross compiler.
                buildInputs = lib.optionals (crossConfig != null) buildInputs;
                propagatedBuildInputs = lib.optionals (crossConfig != null)
                    propagatedBuildInputs;
                # Inputs built by the usual native compiler.
                nativeBuildInputs = nativeBuildInputs ++ lib.optionals
                  (crossConfig == null) buildInputs;
                propagatedNativeBuildInputs = propagatedNativeBuildInputs ++
                  lib.optionals (crossConfig == null) propagatedBuildInputs;
            }))) (
            {
              # The meta attribute is passed in the resulting attribute set,
              # but it's not part of the actual derivation, i.e., it's not
              # passed to the builder and is not a dependency.  But since we
              # include it in the result, it *is* available to nix-env for
              # queries.
              meta = attrs.meta or {};
              passthru = attrs.passthru or {};
            } //
            # Pass through extra attributes that are not inputs, but
            # should be made available to Nix expressions using the
            # derivation (e.g., in assertions).
            (attrs.passthru or {}));

        # Utility flags to test the type of platform.
        isDarwin = result.system == "x86_64-darwin";
        isLinux = result.system == "i686-linux"
               || result.system == "x86_64-linux"
               || result.system == "powerpc-linux"
               || result.system == "armv5tel-linux"
               || result.system == "armv6l-linux"
               || result.system == "armv7l-linux"
               || result.system == "mips64el-linux";
        isGNU = result.system == "i686-gnu";      # GNU/Hurd
        isGlibc = isGNU                           # useful for `stdenvNative'
               || isLinux
               || result.system == "x86_64-kfreebsd-gnu";
        isSunOS = result.system == "i686-solaris"
               || result.system == "x86_64-solaris";
        isCygwin = result.system == "i686-cygwin";
        isFreeBSD = result.system == "i686-freebsd"
               || result.system == "x86_64-freebsd";
        isOpenBSD = result.system == "i686-openbsd"
               || result.system == "x86_64-openbsd";
        isBSD = result.system == "i686-freebsd"
               || result.system == "x86_64-freebsd"
               || result.system == "i686-openbsd"
               || result.system == "x86_64-openbsd";
        isi686 = result.system == "i686-linux"
               || result.system == "i686-gnu"
               || result.system == "i686-freebsd"
               || result.system == "i686-openbsd"
               || result.system == "i386-sunos";
        isx86_64 = result.system == "x86_64-linux"
               || result.system == "x86_64-darwin"
               || result.system == "x86_64-freebsd"
               || result.system == "x86_64-openbsd";
        is64bit = result.system == "x86_64-linux"
                || result.system == "x86_64-darwin"
                || result.system == "x86_64-freebsd"
                || result.system == "x86_64-openbsd";
        isMips = result.system == "mips-linux"
                || result.system == "mips64el-linux";
        isArm = result.system == "armv5tel-linux"
             || result.system == "armv6l-linux"
             || result.system == "armv7l-linux";

        # Utility function: allow stdenv to be easily regenerated with
        # a different setup script.  (See all-packages.nix for an
        # example.)
        regenerate = stdenvGenerator;

        # For convenience, bring in the library functions in lib/ so
        # packages don't have to do that themselves.
        inherit lib;

        inherit fetchurlBoot;

        inherit overrides;
      }

      # Propagate any extra attributes.  For instance, we use this to
      # "lift" packages like curl from the final stdenv for Linux to
      # all-packages.nix for that platform (meaning that it has a line
      # like curl = if stdenv ? curl then stdenv.curl else ...).
      // extraAttrs;

  }.result;


in stdenvGenerator ./setup.sh