core/pkgs/stdenv/generic/default.nix

let
  lib = import ../../../lib;
  stdenv-overridable = lib.makeOverridable (

    argsStdenv@{
      name ? "stdenv",
      preHook ? "",
      initialPath,

      # If we don't have a C compiler, we might either have `cc = null` or `cc =
      # throw ...`, but if we do have a C compiler we should definiely have `cc !=
      # null`.
      #
      # TODO(@Ericson2314): Add assert without creating infinite recursion
      hasCC ? cc != null,
      cc,

      shell,
      allowedRequisites ? null,
      extraAttrs ? { },
      overrides ? (self: super: { }),
      config,
      disallowedRequisites ? [ ],

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

      setupScript ? ./setup.sh,

      extraNativeBuildInputs ? [ ],
      extraBuildInputs ? [ ],
      __stdenvImpureHostDeps ? [ ],
      __extraImpureHostDeps ? [ ],
      stdenvSandboxProfile ? "",
      extraSandboxProfile ? "",

      ## Platform parameters
      ##
      ## The "build" "host" "target" terminology below comes from GNU Autotools. See
      ## its documentation for more information on what those words mean. Note that
      ## each should always be defined, even when not cross compiling.
      ##
      ## For purposes of bootstrapping, think of each stage as a "sliding window"
      ## over a list of platforms. Specifically, the host platform of the previous
      ## stage becomes the build platform of the current one, and likewise the
      ## target platform of the previous stage becomes the host platform of the
      ## current one.
      ##

      # The platform on which packages are built. Consists of `system`, a
      # string (e.g.,`i686-linux') identifying the most import attributes of the
      # build platform, and `platform` a set of other details.
      buildPlatform,

      # The platform on which packages run.
      hostPlatform,

      # The platform which build tools (especially compilers) build for in this stage,
      targetPlatform,

      # The implementation of `mkDerivation`, parameterized with the final stdenv so we can tie the knot.
      # This is convient to have as a parameter so the stdenv "adapters" work better
      mkDerivationFromStdenv ?
        stdenv: (import ./make-derivation.nix { inherit lib config; } stdenv).mkDerivation,
    }:

    let
      defaultNativeBuildInputs =
        extraNativeBuildInputs
        ++ [
          ../../build-support/setup-hooks/audit-tmpdir.sh
          ../../build-support/setup-hooks/compress-man-pages.sh
          ../../build-support/setup-hooks/make-symlinks-relative.sh
          ../../build-support/setup-hooks/move-docs.sh
          ../../build-support/setup-hooks/move-lib64.sh
          ../../build-support/setup-hooks/move-sbin.sh
          ../../build-support/setup-hooks/move-systemd-user-units.sh
          ../../build-support/setup-hooks/multiple-outputs.sh
          ../../build-support/setup-hooks/patch-shebangs.sh
          ../../build-support/setup-hooks/prune-libtool-files.sh
          ../../build-support/setup-hooks/reproducible-builds.sh
          ../../build-support/setup-hooks/set-source-date-epoch-to-latest.sh
          ../../build-support/setup-hooks/strip.sh
        ]
        ++ lib.optionals hasCC [ cc ];

      defaultBuildInputs = extraBuildInputs;

      stdenv = (stdenv-overridable argsStdenv);

    in
    # The stdenv that we are producing.
    derivation (
      lib.optionalAttrs (allowedRequisites != null) {
        allowedRequisites = allowedRequisites ++ defaultNativeBuildInputs ++ defaultBuildInputs;
      }
      // lib.optionalAttrs config.contentAddressedByDefault {
        __contentAddressed = true;
        outputHashAlgo = "sha256";
        outputHashMode = "recursive";
      }
      // {
        inherit name;
        inherit disallowedRequisites;

        # Nix itself uses the `system` field of a derivation to decide where to
        # build it. This is a bit confusing for cross compilation.
        inherit (buildPlatform) system;

        builder = shell;

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

        setup = setupScript;

        # We pretty much never need rpaths on Darwin, since all library path references
        # are absolute unless we go out of our way to make them relative (like with CF)
        # TODO: This really wants to be in stdenv/darwin but we don't have hostPlatform
        # there (yet?) so it goes here until then.
        preHook =
          preHook
          + lib.optionalString buildPlatform.isDarwin ''
            export NIX_DONT_SET_RPATH_FOR_BUILD=1
          ''
          + lib.optionalString (hostPlatform.isDarwin || (!hostPlatform.isElf && !hostPlatform.isMacho)) ''
            export NIX_DONT_SET_RPATH=1
            export NIX_NO_SELF_RPATH=1
          ''
          + lib.optionalString (hostPlatform.isDarwin && hostPlatform.isMacOS) ''
            export MACOSX_DEPLOYMENT_TARGET=${hostPlatform.darwinMinVersion}
          ''
        # TODO this should be uncommented, but it causes stupid mass rebuilds. I
        # think the best solution would just be to fixup linux RPATHs so we don't
        # need to set `-rpath` anywhere.
        # + lib.optionalString targetPlatform.isDarwin ''
        #   export NIX_DONT_SET_RPATH_FOR_TARGET=1
        # ''
        ;

        inherit
          initialPath
          shell
          defaultNativeBuildInputs
          defaultBuildInputs
          ;
      }
      // lib.optionalAttrs buildPlatform.isDarwin {
        __sandboxProfile = stdenvSandboxProfile;
        __impureHostDeps = __stdenvImpureHostDeps;
      }
    )

    // {

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

      inherit buildPlatform hostPlatform targetPlatform;

      inherit
        extraNativeBuildInputs
        extraBuildInputs
        __extraImpureHostDeps
        extraSandboxProfile
        ;

      # Utility flags to test the type of platform.
      inherit (hostPlatform)
        isDarwin
        isLinux
        isSunOS
        isCygwin
        isBSD
        isFreeBSD
        isOpenBSD
        isi686
        isx86_32
        isx86_64
        is32bit
        is64bit
        isAarch32
        isAarch64
        isMips
        isBigEndian
        ;

      # Override `system` so that packages can get the system of the host
      # platform through `stdenv.system`. `system` is originally set to the
      # build platform within the derivation above so that Nix directs the build
      # to correct type of machine.
      inherit (hostPlatform) system;

      mkDerivation = mkDerivationFromStdenv stdenv;

      inherit fetchurlBoot;

      inherit overrides;

      inherit cc hasCC;

      # Convenience for doing some very basic shell syntax checking by parsing a script
      # without running any commands. Because this will also skip `shopt -s extglob`
      # commands and extglob affects the Bash parser, we enable extglob always.
      shellDryRun = "${stdenv.shell} -n -O extglob";

      tests = {
        succeedOnFailure = import ../tests/succeedOnFailure.nix { inherit stdenv; };
      };
      passthru.tests = lib.warn "Use `stdenv.tests` instead. `passthru` is a `mkDerivation` detail." stdenv.tests;
    }

    # 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
  );
in
stdenv-overridable