core/pkgs/stdenv/darwin/default.nix

# This file contains the standard build environment for Darwin. It is based on LLVM and is patterned
# after the Linux stdenv. It shares similar goals to the Linux standard environment in that the
# resulting environment should be built purely and not contain any references to it.
#
# For more on the design of the stdenv and updating it, see `README.md`.
#
# See also the top comments of the Linux stdenv `../linux/default.nix` for a good overview of
# the bootstrap process and working with it.

{ lib, localSystem, crossSystem, config, overlays, crossOverlays ? [ ]
  # Allow passing in bootstrap files directly so we can test the stdenv bootstrap process when changing the bootstrap tools
, bootstrapFiles ? if localSystem.isAarch64 then
  import ./bootstrap-files/aarch64-apple-darwin.nix
else
  import ./bootstrap-files/x86_64-apple-darwin.nix }:

assert crossSystem == localSystem;

let
  inherit (localSystem) system;

  useAppleSDKLibs = localSystem.isAarch64;

  commonImpureHostDeps = [
    "/bin/sh"
    "/usr/lib/libSystem.B.dylib"
    "/usr/lib/system/libunc.dylib" # This dependency is "hidden", so our scanning code doesn't pick it up
  ];

  isFromNixpkgs = pkg: !(isFromBootstrapFiles pkg);
  isFromBootstrapFiles = pkg: pkg.passthru.isFromBootstrapFiles or false;
  isBuiltByNixpkgsCompiler = pkg:
    isFromNixpkgs pkg && isFromNixpkgs pkg.stdenv.cc.cc;
  isBuiltByBootstrapFilesCompiler = pkg:
    isFromNixpkgs pkg && isFromBootstrapFiles pkg.stdenv.cc.cc;

  commonPreHook = ''
    export NIX_ENFORCE_NO_NATIVE=''${NIX_ENFORCE_NO_NATIVE-1}
    export NIX_ENFORCE_PURITY=''${NIX_ENFORCE_PURITY-1}
    export NIX_IGNORE_LD_THROUGH_GCC=1
    unset SDKROOT
  '';

  bootstrapTools = derivation ({
    inherit system;

    name = "bootstrap-tools";
    builder = "${bootstrapFiles.unpack}/bin/bash";

    args = [
      "${bootstrapFiles.unpack}/bootstrap-tools-unpack.sh"
      bootstrapFiles.bootstrapTools
    ];

    PATH = lib.makeBinPath [ (placeholder "out") bootstrapFiles.unpack ];

    __impureHostDeps = commonImpureHostDeps;
  } // lib.optionalAttrs config.contentAddressedByDefault {
    __contentAddressed = true;
    outputHashAlgo = "sha256";
    outputHashMode = "recursive";
  }) // {
    passthru.isFromBootstrapFiles = true;
  };

  stageFun = prevStage:
    { name, overrides ? (self: super: { }), extraNativeBuildInputs ? [ ]
    , extraPreHook ? "" }:

    let
      cc = if prevStage.llvmPackages.clang-unwrapped == null then
        null
      else
        lib.makeOverridable (import ../../build-support/cc-wrapper) {
          name = "${name}-clang-wrapper";

          nativeTools = false;
          nativeLibc = false;

          expand-response-params = lib.optionalString
            (prevStage.stdenv.hasCC or false && prevStage.stdenv.cc
              != "/dev/null") prevStage.expand-response-params;

          extraPackages = [ prevStage.llvmPackages.compiler-rt ];

          extraBuildCommands = let
            inherit (prevStage.llvmPackages)
              clang-unwrapped compiler-rt release_version;
          in ''
            function clangResourceRootIncludePath() {
              clangLib="$1/lib/clang"
              if (( $(ls "$clangLib" | wc -l) > 1 )); then
                echo "Multiple LLVM versions were found at "$clangLib", but there must only be one used when building the stdenv." >&2
                exit 1
              fi
              echo "$clangLib/$(ls -1 "$clangLib")/include"
            }

            rsrc="$out/resource-root"
            mkdir "$rsrc"
            ln -s "$(clangResourceRootIncludePath "${clang-unwrapped.lib}")" "$rsrc"
            ln -s "${compiler-rt.out}/lib"   "$rsrc/lib"
            ln -s "${compiler-rt.out}/share" "$rsrc/share"
            echo "-resource-dir=$rsrc" >> $out/nix-support/cc-cflags
          '';

          cc = prevStage.llvmPackages.clang-unwrapped;
          bintools = prevStage.darwin.binutils;

          isClang = true;
          libc = prevStage.darwin.Libsystem;
          inherit (prevStage.llvmPackages) libcxx;

          inherit lib;
          inherit (prevStage) coreutils gnugrep;

          stdenvNoCC = prevStage.ccWrapperStdenv;
          runtimeShell = prevStage.ccWrapperStdenv.shell;
        };

      bash = prevStage.bash or bootstrapTools;

      thisStdenv = import ../generic lib {
        name = "${name}-stdenv-darwin";

        buildPlatform = localSystem;
        hostPlatform = localSystem;
        targetPlatform = localSystem;

        inherit config;

        extraBuildInputs = [ prevStage.darwin.CF ];
        extraNativeBuildInputs = extraNativeBuildInputs
          ++ [ prevStage.darwin.apple_sdk.sdkRoot ];

        preHook = lib.optionalString (!isBuiltByNixpkgsCompiler bash) ''
          # Don't patch #!/interpreter because it leads to retained
          # dependencies on the bootstrapTools in the final stdenv.
          dontPatchShebangs=1
        '' + ''
          ${commonPreHook}
          ${extraPreHook}
        '' + lib.optionalString (prevStage.darwin ? locale) ''
          export PATH_LOCALE=${prevStage.darwin.locale}/share/locale
        '';

        shell = bash + "/bin/bash";
        initialPath = [ bash bootstrapTools ];

        fetchurlBoot = import ../../build-support/fetchurl {
          inherit lib;
          stdenvNoCC = prevStage.ccWrapperStdenv or thisStdenv;
          curl = bootstrapTools;
        };

        inherit cc;

        # The stdenvs themselves don't use mkDerivation, so I need to specify this here
        __stdenvImpureHostDeps = commonImpureHostDeps;
        __extraImpureHostDeps = commonImpureHostDeps;

        # Using the bootstrap tools curl for fetchers allows the stdenv bootstrap to avoid
        # having a dependency on curl, allowing curl to be updated without triggering a
        # new stdenv bootstrap on Darwin.
        overrides = self: super:
          (overrides self super) // {
            fetchurl = thisStdenv.fetchurlBoot;
            fetchpatch = super.fetchpatch.override { inherit (self) fetchurl; };
            fetchgit = super.fetchgit.override {
              git = super.git.override { curl = bootstrapTools; };
            };
            fetchzip = super.fetchzip.override { inherit (self) fetchurl; };
          };
      };

    in {
      inherit config overlays;
      stdenv = thisStdenv;
    };
in assert bootstrapTools.passthru.isFromBootstrapFiles or false; # sanity check
[
  ({ }: {
    __raw = true;

    coreutils = null;
    gnugrep = null;

    pbzx = null;
    cpio = null;

    darwin = {
      apple_sdk.sdkRoot = null;
      binutils = null;
      binutils-unwrapped = null;
      cctools = null;
      print-reexports = null;
      rewrite-tbd = null;
      sigtool = null;
      CF = null;
      Libsystem = null;
    };

    llvmPackages = {
      clang-unwrapped = null;
      libllvm = null;
      libcxx = null;
      compiler-rt = null;
    };
  })

  # Create a stage with the bootstrap tools. This will be used to build the subsequent stages and
  # build up the standard environment.
  #
  # Note: Each stage depends only on the the packages in `prevStage`. If a package is not to be
  # rebuilt, it should be passed through by inheriting it.
  (prevStage:
    stageFun prevStage {
      name = "bootstrap-stage0";

      overrides = self: super: {
        # We thread stage0's stdenv through under this name so downstream stages
        # can use it for wrapping gcc too. This way, downstream stages don't need
        # to refer to this stage directly, which violates the principle that each
        # stage should only access the stage that came before it.
        ccWrapperStdenv = self.stdenv;

        bash = bootstrapTools;
        coreutils = bootstrapTools;
        cpio = bootstrapTools;
        gnugrep = bootstrapTools;
        pbzx = bootstrapTools;

        darwin = super.darwin.overrideScope (selfDarwin: superDarwin:
          {
            # Prevent CF from being propagated to the initial stdenv. Packages that require it
            # will have to manually add it to their build inputs.
            CF = null;

            binutils-unwrapped = bootstrapTools // { version = "boot"; };

            binutils = super.wrapBintoolsWith {
              name = "bootstrap-stage0-binutils-wrapper";

              nativeTools = false;
              nativeLibc = false;

              expand-response-params = "";
              libc = selfDarwin.Libsystem;

              inherit lib;
              inherit (self) stdenvNoCC coreutils gnugrep;
              runtimeShell = self.stdenvNoCC.shell;

              bintools = selfDarwin.binutils-unwrapped;

              inherit (selfDarwin) postLinkSignHook signingUtils;
            };

            cctools = bootstrapTools // {
              targetPrefix = "";
              version = "boot";
              man = bootstrapTools;
            };

            locale = self.stdenv.mkDerivation {
              name = "bootstrap-stage0-locale";
              buildCommand = ''
                mkdir -p $out/share/locale
              '';
            };

            print-reexports = bootstrapTools;

            rewrite-tbd = bootstrapTools;

            sigtool = bootstrapTools;
          } // lib.optionalAttrs (!useAppleSDKLibs) {
            Libsystem = self.stdenv.mkDerivation {
              name = "bootstrap-stage0-Libsystem";
              buildCommand = ''
                mkdir -p $out

                cp -r ${selfDarwin.darwin-stubs}/usr/lib $out/lib
                chmod -R +w $out/lib
                substituteInPlace $out/lib/libSystem.B.tbd --replace /usr/lib/system $out/lib/system

                ln -s libSystem.B.tbd $out/lib/libSystem.tbd

                for name in c dbm dl info m mx poll proc pthread rpcsvc util gcc_s.10.4 gcc_s.10.5; do
                  ln -s libSystem.tbd $out/lib/lib$name.tbd
                done

                ln -s ${bootstrapTools}/lib/*.o $out/lib

                ln -s ${bootstrapTools}/lib/libresolv.9.dylib $out/lib
                ln -s libresolv.9.dylib $out/lib/libresolv.dylib

                ln -s ${bootstrapTools}/include-Libsystem $out/include
              '';
              passthru.isFromBootstrapFiles = true;
            };
          });

        llvmPackages = super.llvmPackages // (let
          tools = super.llvmPackages.tools.extend (selfTools: _: {
            libclang = self.stdenv.mkDerivation {
              name = "bootstrap-stage0-clang";
              version = "boot";
              outputs = [ "out" "lib" ];
              buildCommand = ''
                mkdir -p $out/lib
                ln -s $out $lib
                ln -s ${bootstrapTools}/bin       $out/bin
                ln -s ${bootstrapTools}/lib/clang $out/lib
                ln -s ${bootstrapTools}/include   $out
              '';
              passthru = {
                isFromBootstrapFiles = true;
                hardeningUnsupportedFlags = [ "fortify3" "zerocallusedregs" ];
              };
            };
            clang-unwrapped = selfTools.libclang;
            libllvm = self.stdenv.mkDerivation {
              name = "bootstrap-stage0-llvm";
              outputs = [ "out" "lib" ];
              buildCommand = ''
                mkdir -p $out/bin $out/lib
                ln -s $out $lib
                ln -s ${bootstrapTools}/bin/strip    $out/bin/llvm-strip
                ln -s ${bootstrapTools}/lib/libLLVM* $out/lib
              '';
              passthru.isFromBootstrapFiles = true;
            };
            llvm = selfTools.libllvm;
          });
          libraries = super.llvmPackages.libraries.extend (_: _: {
            libcxx = self.stdenv.mkDerivation {
              name = "bootstrap-stage0-libcxx";
              buildCommand = ''
                mkdir -p $out/lib $out/include
                ln -s ${bootstrapTools}/lib/libc++.dylib $out/lib
                ln -s ${bootstrapTools}/include/c++      $out/include
              '';
              passthru = {
                isLLVM = true;
                isFromBootstrapFiles = true;
              };
            };
            compiler-rt = self.stdenv.mkDerivation {
              name = "bootstrap-stage0-compiler-rt";
              buildCommand = ''
                mkdir -p $out/lib $out/share
                ln -s ${bootstrapTools}/lib/libclang_rt* $out/lib
                ln -s ${bootstrapTools}/lib/darwin       $out/lib
              '';
              passthru.isFromBootstrapFiles = true;
            };
          });
        in { inherit tools libraries; } // tools // libraries);
      };

      # The bootstrap tools may use `strip` from cctools, so use a compatible set of flags until LLVM
      # is rebuilt, and darwin.binutils can use its implementation instead.
      extraPreHook = ''
        stripAllFlags=" "    # the cctools "strip" command doesn't know "-s"
        stripDebugFlags="-S" # the cctools "strip" command does something odd with "-p"
      '';
    })

  # This stage is primarily responsible for building the linker and setting up versions of
  # certain dependencies needed by the rest of the build process. It is necessary to rebuild the
  # linker because the `compiler-rt` build process checks the version and attempts to manually
  # run `codesign` if it detects a version of `ld64` it considers too old. If that happens, the
  # build process will fail for a few different reasons:
  #  - sigtool is too old and does not accept the `--sign` argument;
  #  - sigtool is new enough to accept the `--sign` argument, but it aborts when it is invoked on a
  #    binary that is already signed; or
  #  - compiler-rt attempts to invoke `codesign` on x86_64-darwin, but `sigtool` is not currently
  #    part of the x86_64-darwin bootstrap tools.
  #
  # This stage also builds CF and Libsystem to simplify assertions and assumptions for later by
  # making sure both packages are present on x86_64-darwin and aarch64-darwin.
  (prevStage:
    # previous stage0 stdenv:
    assert lib.all isFromBootstrapFiles (with prevStage;
      [ bash coreutils cpio gnugrep ]
      ++ lib.optionals useAppleSDKLibs [ pbzx ]);

    assert lib.all isFromBootstrapFiles (with prevStage.darwin; [
      binutils-unwrapped
      cctools
      print-reexports
      rewrite-tbd
      sigtool
    ]);

    assert (!useAppleSDKLibs)
      -> lib.all isFromBootstrapFiles (with prevStage.darwin; [ Libsystem ]);
    assert useAppleSDKLibs
      -> lib.all isFromNixpkgs (with prevStage.darwin; [ Libsystem ]);
    assert lib.all isFromNixpkgs (with prevStage.darwin; [ dyld launchd xnu ]);
    assert (with prevStage.darwin; (!useAppleSDKLibs) -> CF == null);

    assert lib.all isFromBootstrapFiles (with prevStage.llvmPackages; [
      clang-unwrapped
      libclang
      libllvm
      llvm
      compiler-rt
      libcxx
    ]);

    stageFun prevStage {
      name = "bootstrap-stage1";

      overrides = self: super: {
        inherit (prevStage) ccWrapperStdenv coreutils gnugrep;

        # Use this stage’s CF to build CMake. It’s required but can’t be included in the stdenv.
        cmake = self.cmakeMinimal;
        cmakeMinimal = super.cmakeMinimal.overrideAttrs
          (old: { buildInputs = old.buildInputs ++ [ self.darwin.CF ]; });

        # Disable tests because they use dejagnu, which fails to run.
        libffi = super.libffi.override { doCheck = false; };

        # Avoid pulling in a full python and its extra dependencies for the llvm/clang builds.
        libxml2 = super.libxml2.override { pythonSupport = false; };

        ninja = super.ninja.override { buildDocs = false; };

        # Use this stage’s CF to build Python. It’s required but can’t be included in the stdenv.
        python3 = self.python3Minimal;
        python3Minimal = super.python3Minimal.overrideAttrs
          (old: { buildInputs = old.buildInputs ++ [ self.darwin.CF ]; });

        darwin = super.darwin.overrideScope (selfDarwin: superDarwin: {
          apple_sdk = superDarwin.apple_sdk // {
            inherit (prevStage.darwin.apple_sdk) sdkRoot;
          };

          # Use this stage’s CF to build configd. It’s required but can’t be included in the stdenv.
          configd = superDarwin.configd.overrideAttrs (old: {
            buildInputs = old.buildInputs or [ ] ++ [ self.darwin.CF ];
          });

          signingUtils = prevStage.darwin.signingUtils.override {
            inherit (selfDarwin) sigtool;
          };

          postLinkSignHook = prevStage.darwin.postLinkSignHook.override {
            inherit (selfDarwin) sigtool;
          };

          binutils = superDarwin.binutils.override {
            inherit (self) coreutils;
            inherit (selfDarwin) postLinkSignHook signingUtils;

            bintools = selfDarwin.binutils-unwrapped;
            libc = selfDarwin.Libsystem;
            # TODO(@sternenseemann): can this be removed?
            runtimeShell = "${bootstrapTools}/bin/bash";
          };

          binutils-unwrapped = superDarwin.binutils-unwrapped.override {
            inherit (selfDarwin) cctools;
          };

          cctools = selfDarwin.cctools-port;
        });

        llvmPackages = super.llvmPackages // (let
          tools = super.llvmPackages.tools.extend (_: _: {
            inherit (prevStage.llvmPackages)
              clang-unwrapped libclang libllvm llvm;
          });
          libraries = super.llvmPackages.libraries.extend
            (_: _: { inherit (prevStage.llvmPackages) compiler-rt libcxx; });
        in {
          inherit tools libraries;
          inherit (prevStage.llvmPackages) release_version;
        } // tools // libraries);
      };

      extraNativeBuildInputs = lib.optionals localSystem.isAarch64 [
        prevStage.updateAutotoolsGnuConfigScriptsHook
        prevStage.gnu-config
      ];

      # The bootstrap tools may use `strip` from cctools, so use a compatible set of flags until LLVM
      # is rebuilt, and darwin.binutils can use its implementation instead.
      extraPreHook = ''
        stripAllFlags=" "    # the cctools "strip" command doesn't know "-s"
        stripDebugFlags="-S" # the cctools "strip" command does something odd with "-p"

        # Don’t assume the ld64 in bootstrap tools supports response files. Only recent versions do.
        export NIX_LD_USE_RESPONSE_FILE=0
      '';
    })

  # Build cctools, Python, and sysctl for use by LLVM’s check phase. They must be built in
  # their stage to prevent infinite recursions and to make sure the stdenv used to build
  # LLVM has the newly built cctools instead of the one from the bootstrap tools.
  (prevStage:
    # previous stage1 stdenv:
    assert lib.all isFromBootstrapFiles (with prevStage; [ coreutils gnugrep ]);

    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage; [
      autoconf
      automake
      bash
      binutils-unwrapped
      bison
      brotli
      cmake
      cpio
      cyrus_sasl
      db
      ed
      expat
      flex
      gettext
      gmp
      groff
      icu
      libedit
      libffi
      libiconv
      libidn2
      libkrb5
      libssh2
      libtool
      libunistring
      libxml2
      m4
      ncurses
      nghttp2
      ninja
      openldap
      openssh
      openssl
      patchutils
      pbzx
      perl
      pkg-config.pkg-config
      python3
      python3Minimal
      scons
      serf
      sqlite
      subversion
      texinfo
      unzip
      which
      xz
      zlib
      zstd
    ]);

    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage.darwin; [
      binutils-unwrapped
      cctools
      locale
      libtapi
      print-reexports
      rewrite-tbd
      sigtool
    ]);
    assert (!useAppleSDKLibs) -> lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.darwin; [ Libsystem configd ]);
    assert (!useAppleSDKLibs)
      -> lib.all isFromNixpkgs (with prevStage.darwin; [ CF ]);
    assert useAppleSDKLibs -> lib.all isFromNixpkgs
      (with prevStage.darwin; [ CF Libsystem libobjc ]);
    assert lib.all isFromNixpkgs (with prevStage.darwin; [ dyld launchd xnu ]);

    assert lib.all isFromBootstrapFiles (with prevStage.llvmPackages; [
      clang-unwrapped
      libclang
      libllvm
      llvm
      compiler-rt
      libcxx
    ]);

    assert lib.getVersion prevStage.stdenv.cc.bintools.bintools == "boot";

    stageFun prevStage {
      name = "bootstrap-stage1-sysctl";

      overrides = self: super: {
        inherit (prevStage)
          ccWrapperStdenv autoconf automake bash binutils binutils-unwrapped
          bison brotli cmake cmakeMinimal coreutils cpio cyrus_sasl db ed expat
          flex gettext gmp gnugrep groff icu libedit libffi libiconv libidn2
          libkrb5 libssh2 libtool libunistring libxml2 m4 ncurses nghttp2 ninja
          openldap openssh openssl patchutils pbzx perl pkg-config
          python3Minimal scons sed serf sharutils sqlite subversion texinfo
          unzip which xz zlib zstd;

        # Support for the SystemConfiguration framework is required to run the LLVM tests, but trying
        # to override python3Minimal does not appear to work.
        python3 = (super.python3.override {
          inherit (self) libffi;
          inherit (self.darwin) configd;
          openssl = null;
          readline = null;
          ncurses = null;
          gdbm = null;
          sqlite = null;
          tzdata = null;
          stripConfig = true;
          stripIdlelib = true;
          stripTests = true;
          stripTkinter = true;
          rebuildBytecode = false;
          stripBytecode = true;
          includeSiteCustomize = false;
          enableOptimizations = false;
          enableLTO = false;
          mimetypesSupport = false;
        }).overrideAttrs (_: { pname = "python3-minimal-scproxy"; });

        darwin = super.darwin.overrideScope (_: superDarwin: {
          inherit (prevStage.darwin)
            CF sdkRoot Libsystem binutils-unwrapped cctools cctools-port configd
            darwin-stubs dyld launchd libclosure libdispatch libobjc locale
            objc4 postLinkSignHook print-reexports rewrite-tbd signingUtils
            sigtool;

          apple_sdk = superDarwin.apple_sdk // {
            inherit (prevStage.darwin.apple_sdk) sdkRoot;
          };
        });

        llvmPackages = super.llvmPackages // (let
          tools = super.llvmPackages.tools.extend (_: _: {
            inherit (prevStage.llvmPackages)
              clang-unwrapped libclang libllvm llvm;
            clang = prevStage.stdenv.cc;
          });
          libraries = super.llvmPackages.libraries.extend
            (_: _: { inherit (prevStage.llvmPackages) compiler-rt libcxx; });
        in {
          inherit tools libraries;
          inherit (prevStage.llvmPackages) release_version;
        } // tools // libraries);
      };

      extraNativeBuildInputs = lib.optionals localSystem.isAarch64 [
        prevStage.updateAutotoolsGnuConfigScriptsHook
        prevStage.gnu-config
      ];

      # Until LLVM is rebuilt, assume `strip` is the one from cctools.
      extraPreHook = ''
        stripAllFlags=" "    # the cctools "strip" command doesn't know "-s"
        stripDebugFlags="-S" # the cctools "strip" command does something odd with "-p"
      '';
    })

  # First rebuild of LLVM. While this LLVM is linked to a bunch of junk from the bootstrap tools,
  # the libc++ and libc++abi it produces are not. The compiler will be rebuilt in a later stage,
  # but those libraries will be used in the final stdenv.
  #
  # Rebuild coreutils and gnugrep to avoid unwanted references to the bootstrap tools on `PATH`.
  (prevStage:
    # previous stage-sysctl stdenv:
    assert lib.all isFromBootstrapFiles (with prevStage; [ coreutils gnugrep ]);

    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage; [
      autoconf
      automake
      bash
      binutils-unwrapped
      bison
      brotli
      cmake
      cpio
      cyrus_sasl
      db
      ed
      expat
      flex
      gettext
      gmp
      groff
      icu
      libedit
      libffi
      libiconv
      libidn2
      libkrb5
      libssh2
      libtool
      libunistring
      libxml2
      m4
      ncurses
      nghttp2
      ninja
      openldap
      openssh
      openssl
      patchutils
      pbzx
      perl
      pkg-config.pkg-config
      python3
      python3Minimal
      scons
      serf
      sqlite
      subversion
      sysctl.provider
      texinfo
      unzip
      which
      xz
      zlib
      zstd
    ]);

    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage.darwin; [
      binutils-unwrapped
      cctools
      locale
      libtapi
      print-reexports
      rewrite-tbd
      sigtool
    ]);

    assert (!useAppleSDKLibs) -> lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.darwin; [ Libsystem configd ]);
    assert (!useAppleSDKLibs)
      -> lib.all isFromNixpkgs (with prevStage.darwin; [ CF ]);
    assert useAppleSDKLibs -> lib.all isFromNixpkgs
      (with prevStage.darwin; [ CF Libsystem libobjc ]);
    assert lib.all isFromNixpkgs (with prevStage.darwin; [ dyld launchd xnu ]);

    assert lib.all isFromBootstrapFiles (with prevStage.llvmPackages; [
      clang-unwrapped
      libclang
      libllvm
      llvm
      compiler-rt
      libcxx
    ]);

    assert lib.getVersion prevStage.stdenv.cc.bintools.bintools
      == lib.getVersion prevStage.darwin.cctools-port;

    stageFun prevStage {
      name = "bootstrap-stage-xclang";

      overrides = self: super: {
        inherit (prevStage)
          ccWrapperStdenv autoconf automake bash binutils binutils-unwrapped
          bison brotli cmake cmakeMinimal cpio cyrus_sasl db ed expat flex
          gettext gmp groff icu libedit libffi libiconv libidn2 libkrb5 libssh2
          libtool libunistring libxml2 m4 ncurses nghttp2 ninja openldap openssh
          openssl patchutils pbzx perl pkg-config python3 python3Minimal scons
          sed serf sharutils sqlite subversion sysctl texinfo unzip which xz
          zlib zstd;

        # Switch from cctools-port to cctools-llvm now that LLVM has been built.
        darwin = super.darwin.overrideScope (_: superDarwin: {
          inherit (prevStage.darwin)
            CF Libsystem configd darwin-stubs dyld launchd libclosure
            libdispatch libobjc locale objc4 postLinkSignHook print-reexports
            rewrite-tbd signingUtils sigtool;

          apple_sdk = superDarwin.apple_sdk // {
            inherit (prevStage.darwin.apple_sdk) sdkRoot;
          };

          # Avoid building unnecessary Python dependencies due to building LLVM manpages.
          cctools-llvm =
            superDarwin.cctools-llvm.override { enableManpages = false; };
        });

        llvmPackages = super.llvmPackages // (let
          llvmMajor = lib.versions.major super.llvmPackages.release_version;

          # libc++, and libc++abi do not need CoreFoundation. Avoid propagating the CF from prior
          # stages to the final stdenv via rpath by dropping it from `extraBuildInputs`.
          stdenvNoCF = self.stdenv.override { extraBuildInputs = [ ]; };

          libcxxBootstrapStdenv = self.overrideCC stdenvNoCF
            (self.llvmPackages.clangNoCompilerRtWithLibc.override {
              nixSupport.cc-cflags = [ "-nostdlib" ];
              nixSupport.cc-ldflags = [ "-lSystem" ];
            });

          libraries = super.llvmPackages.libraries.extend (selfLib: superLib: {
            compiler-rt = null;
            libcxx =
              superLib.libcxx.override ({ stdenv = libcxxBootstrapStdenv; });
          });
        in { inherit libraries; } // libraries);
      };

      extraNativeBuildInputs = lib.optionals localSystem.isAarch64 [
        prevStage.updateAutotoolsGnuConfigScriptsHook
        prevStage.gnu-config
      ];

      extraPreHook = ''
        stripAllFlags=" "    # the cctools "strip" command doesn't know "-s"
        stripDebugFlags="-S" # the cctools "strip" command does something odd with "-p"
      '';
    })

  # This stage rebuilds Libsystem. It also rebuilds bash, which will be needed in later stages
  # to use in patched shebangs (e.g., to make sure `icu-config` uses bash from nixpkgs).
  (prevStage:
    # previous stage-xclang stdenv:
    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage; [
      autoconf
      automake
      bash
      binutils-unwrapped
      bison
      cmake
      cmakeMinimal
      coreutils
      cpio
      cyrus_sasl
      db
      ed
      expat
      flex
      gettext
      gmp
      gnugrep
      groff
      icu
      libedit
      libtool
      m4
      ninja
      openbsm
      openldap
      openpam
      openssh
      patchutils
      pbzx
      perl
      pkg-config.pkg-config
      python3
      python3Minimal
      scons
      serf
      sqlite
      subversion
      sysctl.provider
      texinfo
      unzip
      which
      xz
    ]);

    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage; [
      brotli
      libffi
      libiconv
      libidn2
      libkrb5
      libssh2
      libunistring
      libxml2
      ncurses
      nghttp2
      openssl
      zlib
      zstd
    ]);

    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage.darwin; [
      binutils-unwrapped
      cctools
      locale
      libtapi
      print-reexports
      rewrite-tbd
      sigtool
    ]);

    assert (!useAppleSDKLibs) -> lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.darwin; [ Libsystem configd ]);
    assert (!useAppleSDKLibs)
      -> lib.all isFromNixpkgs (with prevStage.darwin; [ CF ]);
    assert useAppleSDKLibs -> lib.all isFromNixpkgs
      (with prevStage.darwin; [ CF Libsystem libobjc ]);
    assert lib.all isFromNixpkgs
      (with prevStage.darwin; [ dyld launchd libclosure libdispatch xnu ]);

    assert lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.llvmPackages; [ clang-unwrapped libclang libllvm llvm ]);
    assert lib.all isBuiltByNixpkgsCompiler
      (with prevStage.llvmPackages; [ libcxx ]);
    assert prevStage.llvmPackages.compiler-rt == null;

    assert lib.getVersion prevStage.stdenv.cc.bintools.bintools
      == lib.getVersion prevStage.darwin.cctools-port;

    stageFun prevStage {

      name = "bootstrap-stage2-Libsystem";

      overrides = self: super: {
        inherit (prevStage)
          ccWrapperStdenv autoconf automake binutils-unwrapped bison brotli
          cmake cmakeMinimal coreutils cpio cyrus_sasl db ed expat flex gettext
          gmp gnugrep groff icu libedit libffi libiconv libidn2 libkrb5 libssh2
          libtool libunistring libxml2 m4 ncurses nghttp2 ninja openbsm openldap
          openpam openssh openssl patchutils pbzx perl pkg-config python3
          python3Minimal scons serf sqlite subversion sysctl texinfo unzip which
          xz zlib zstd;

        # Bash must be linked against the system CoreFoundation instead of the open-source one.
        # Otherwise, there will be a dependency cycle: bash -> CF -> icu -> bash (for icu^dev).
        bash = super.bash.overrideAttrs (super: {
          buildInputs = super.buildInputs
            ++ [ self.darwin.apple_sdk.frameworks.CoreFoundation ];
        });

        darwin = super.darwin.overrideScope (selfDarwin: superDarwin: {
          inherit (prevStage.darwin)
            CF binutils-unwrapped cctools configd darwin-stubs launchd libobjc
            libtapi locale objc4 print-reexports rewrite-tbd signingUtils
            sigtool;

          apple_sdk = superDarwin.apple_sdk // {
            inherit (prevStage.darwin.apple_sdk) sdkRoot;
          };
        });

        llvmPackages = super.llvmPackages // (let
          tools = super.llvmPackages.tools.extend (_: _: {
            inherit (prevStage.llvmPackages)
              clang-unwrapped clangNoCompilerRtWithLibc libclang libllvm llvm;
          });

          libraries = super.llvmPackages.libraries.extend (selfLib: superLib: {
            inherit (prevStage.llvmPackages) compiler-rt libcxx;
          });
        in {
          inherit tools libraries;
          inherit (prevStage.llvmPackages) release_version;
        } // tools // libraries);

        # Don’t link anything in this stage against CF to prevent propagating CF from prior stages to
        # the final stdenv, which happens because of the rpath hook.
        stdenv =
          let stdenvNoCF = super.stdenv.override { extraBuildInputs = [ ]; };
          in self.overrideCC stdenvNoCF
          (self.llvmPackages.clangNoCompilerRtWithLibc.override {
            inherit (self.llvmPackages) libcxx;
          });
      };

      extraNativeBuildInputs = lib.optionals localSystem.isAarch64 [
        prevStage.updateAutotoolsGnuConfigScriptsHook
        prevStage.gnu-config
      ];

      extraPreHook = ''
        stripDebugFlags="-S" # llvm-strip does not support "-p" for Mach-O
      '';
    })

  # This stage rebuilds CF, compiler-rt, and the sdkRoot derivation.
  #
  # CF requires:
  # - aarch64-darwin: libobjc (due to being apple_sdk.frameworks.CoreFoundation instead of swift-corefoundation)
  # - x86_64-darwin: libiconv libxml2 icu zlib
  (prevStage:
    # previous stage2-Libsystem stdenv:
    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage; [
      autoconf
      automake
      binutils-unwrapped
      bison
      brotli
      cmake
      cmakeMinimal
      coreutils
      cpio
      cyrus_sasl
      db
      ed
      expat
      flex
      gettext
      gmp
      gnugrep
      groff
      icu
      libedit
      libidn2
      libkrb5
      libssh2
      libtool
      libunistring
      m4
      nghttp2
      ninja
      openbsm
      openldap
      openpam
      openssh
      openssl
      patchutils
      pbzx
      perl
      pkg-config.pkg-config
      python3
      python3Minimal
      scons
      serf
      sqlite
      subversion
      sysctl.provider
      texinfo
      unzip
      which
      xz
      zstd
    ]);

    assert lib.all isBuiltByNixpkgsCompiler (with prevStage; [ bash ]);

    assert lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage; [ libffi libiconv libxml2 ncurses zlib zstd ]);

    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage.darwin; [
      binutils-unwrapped
      cctools
      locale
      libtapi
      print-reexports
      rewrite-tbd
      sigtool
    ]);

    assert (!useAppleSDKLibs) -> lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.darwin; [ configd ]);
    assert (!useAppleSDKLibs) -> lib.all isBuiltByNixpkgsCompiler
      (with prevStage.darwin; [ Libsystem ]);
    assert (!useAppleSDKLibs)
      -> lib.all isFromNixpkgs (with prevStage.darwin; [ CF ]);
    assert useAppleSDKLibs -> lib.all isFromNixpkgs
      (with prevStage.darwin; [ CF Libsystem libobjc ]);
    assert lib.all isFromNixpkgs
      (with prevStage.darwin; [ dyld launchd libclosure libdispatch xnu ]);

    assert lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.llvmPackages; [ clang-unwrapped libclang libllvm llvm ]);
    assert lib.all isBuiltByNixpkgsCompiler
      (with prevStage.llvmPackages; [ libcxx ]);
    assert prevStage.llvmPackages.compiler-rt == null;

    assert lib.getVersion prevStage.stdenv.cc.bintools.bintools
      == lib.getVersion prevStage.darwin.cctools-llvm;

    stageFun prevStage {

      name = "bootstrap-stage2-CF";

      overrides = self: super: {
        inherit (prevStage)
          ccWrapperStdenv autoconf automake bash bison brotli cmake cmakeMinimal
          coreutils cpio cyrus_sasl db ed expat flex gettext gmp gnugrep groff
          libedit libidn2 libkrb5 libssh2 libtool libunistring m4 ncurses
          nghttp2 ninja openbsm openldap openpam openssh openssl patchutils pbzx
          perl pkg-config python3 python3Minimal scons serf sqlite subversion
          sysctl texinfo unzip which xz zstd;

        # Avoid pulling in a full python and its extra dependencies for the llvm/clang builds.
        libxml2 = super.libxml2.override { pythonSupport = false; };

        darwin = super.darwin.overrideScope (selfDarwin: superDarwin: {
          inherit (prevStage.darwin)
            Libsystem configd darwin-stubs launchd locale print-reexports
            rewrite-tbd signingUtils sigtool;

          # Rewrap binutils so it uses the rebuilt Libsystem.
          binutils = superDarwin.binutils.override {
            inherit (prevStage) expand-response-params;
            libc = selfDarwin.Libsystem;
          } // {
            passthru = {
              inherit (prevStage.bintools.passthru) isFromBootstrapFiles;
            };
          };

          # Avoid building unnecessary Python dependencies due to building LLVM manpages.
          cctools-llvm =
            superDarwin.cctools-llvm.override { enableManpages = false; };
        });

        llvmPackages = super.llvmPackages // (let
          tools = super.llvmPackages.tools.extend (_: _: {
            inherit (prevStage.llvmPackages)
              clang-unwrapped clangNoCompilerRtWithLibc libclang libllvm llvm;
            clang = prevStage.stdenv.cc;
          });

          libraries = super.llvmPackages.libraries.extend (selfLib: superLib: {
            inherit (prevStage.llvmPackages) libcxx;

            # Make sure compiler-rt is linked against the CF from this stage, which can be
            # propagated to the final stdenv. CF is required by ASAN.
            compiler-rt = superLib.compiler-rt.override ({
              inherit (self.llvmPackages) libllvm;
              stdenv =
                self.stdenv.override { extraBuildInputs = [ self.darwin.CF ]; };
            });
          });
        in {
          inherit tools libraries;
          inherit (prevStage.llvmPackages) release_version;
        } // tools // libraries);

        # Don’t link anything in this stage against CF to prevent propagating CF from prior stages to
        # the final stdenv, which happens because of the rpath hook. Also don’t use a stdenv with
        # compiler-rt because it needs to be built in this stage.
        stdenv =
          let stdenvNoCF = super.stdenv.override { extraBuildInputs = [ ]; };
          in self.overrideCC stdenvNoCF
          (self.llvmPackages.clangNoCompilerRtWithLibc.override {
            inherit (self.llvmPackages) libcxx;

            # Make sure the stdenv is using the Libsystem that will be propagated to the final stdenv.
            libc = self.darwin.Libsystem;
            bintools =
              self.llvmPackages.clangNoCompilerRtWithLibc.bintools.override {
                libc = self.darwin.Libsystem;
              };
          });
      };

      extraNativeBuildInputs = lib.optionals localSystem.isAarch64 [
        prevStage.updateAutotoolsGnuConfigScriptsHook
        prevStage.gnu-config
      ];

      extraPreHook = ''
        stripDebugFlags="-S" # llvm-strip does not support "-p" for Mach-O
      '';
    })

  # Rebuild LLVM with LLVM. This stage also rebuilds certain dependencies needed by LLVM.
  #
  # LLVM requires: libcxx libffi libiconv libxml2 ncurses zlib
  (prevStage:
    # previous stage2-CF stdenv:
    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage; [
      autoconf
      automake
      bison
      brotli
      cmake
      cmakeMinimal
      coreutils
      cpio
      cyrus_sasl
      db
      ed
      expat
      flex
      gettext
      gmp
      gnugrep
      groff
      libedit
      libidn2
      libkrb5
      libssh2
      libtool
      libunistring
      m4
      ncurses
      nghttp2
      ninja
      openbsm
      openldap
      openpam
      openssh
      openssl
      patchutils
      pbzx
      perl
      pkg-config.pkg-config
      python3
      python3Minimal
      scons
      serf
      sqlite
      subversion
      sysctl.provider
      texinfo
      unzip
      which
      xz
      zstd
    ]);
    assert lib.all isBuiltByNixpkgsCompiler (with prevStage; [
      bash
      binutils-unwrapped
      icu
      libffi
      libiconv
      libxml2
      zlib
    ]);

    assert lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.darwin; [ locale print-reexports rewrite-tbd sigtool ]);
    assert lib.all isBuiltByNixpkgsCompiler
      (with prevStage.darwin; [ binutils-unwrapped cctools libtapi ]);

    assert (!useAppleSDKLibs) -> lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.darwin; [ configd ]);
    assert (!useAppleSDKLibs) -> lib.all isBuiltByNixpkgsCompiler
      (with prevStage.darwin; [ Libsystem ]);
    assert (!useAppleSDKLibs)
      -> lib.all isFromNixpkgs (with prevStage.darwin; [ CF ]);
    assert useAppleSDKLibs -> lib.all isFromNixpkgs
      (with prevStage.darwin; [ CF Libsystem libobjc ]);
    assert lib.all isFromNixpkgs
      (with prevStage.darwin; [ dyld launchd libclosure libdispatch xnu ]);

    assert lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.llvmPackages; [ clang-unwrapped libclang libllvm llvm ]);
    assert lib.all isBuiltByNixpkgsCompiler
      (with prevStage.llvmPackages; [ libcxx ]);

    assert lib.getVersion prevStage.stdenv.cc.bintools.bintools
      == lib.getVersion prevStage.darwin.cctools-llvm;

    stageFun prevStage {

      name = "bootstrap-stage3";

      overrides = self: super: {
        inherit (prevStage)
          ccWrapperStdenv autoconf automake bash binutils binutils-unwrapped
          bison brotli cmake cmakeMinimal coreutils cpio cyrus_sasl db ed expat
          flex gettext gmp gnugrep groff libedit libidn2 libkrb5 libssh2 libtool
          libunistring m4 nghttp2 ninja openbsm openldap openpam openssh openssl
          patchutils pbzx perl pkg-config python3 python3Minimal scons sed serf
          sharutils sqlite subversion sysctl texinfo unzip which xz zstd

          # CF dependencies - don’t rebuild them.
          icu libiconv libxml2 zlib;

        # Disable tests because they use dejagnu, which fails to run.
        libffi = super.libffi.override { doCheck = false; };

        darwin = super.darwin.overrideScope (selfDarwin: superDarwin: {
          inherit (prevStage.darwin)
            CF Libsystem binutils binutils-unwrapped cctools cctools-llvm
            cctools-port configd darwin-stubs dyld launchd libclosure
            libdispatch libobjc libtapi locale objc4 postLinkSignHook
            print-reexports rewrite-tbd signingUtils sigtool;

          apple_sdk = superDarwin.apple_sdk // {
            inherit (prevStage.darwin.apple_sdk) sdkRoot;
          };
        });

        llvmPackages = super.llvmPackages // (let
          libraries = super.llvmPackages.libraries.extend
            (_: _: { inherit (prevStage.llvmPackages) compiler-rt libcxx; });
        in { inherit libraries; } // libraries);
      };

      extraNativeBuildInputs = lib.optionals localSystem.isAarch64 [
        prevStage.updateAutotoolsGnuConfigScriptsHook
        prevStage.gnu-config
      ];

      extraPreHook = ''
        stripDebugFlags="-S" # llvm-strip does not support "-p" for Mach-O
      '';
    })

  # Construct a standard environment with the new clang. Also use the new compiler to rebuild
  # everything that will be part of the final stdenv and isn’t required by it, CF, or Libsystem.
  (prevStage:
    # previous stage3 stdenv:
    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage; [
      autoconf
      automake
      bison
      brotli
      cmake
      cmakeMinimal
      coreutils
      cpio
      cyrus_sasl
      db
      ed
      expat
      flex
      gettext
      gmp
      gnugrep
      groff
      libedit
      libidn2
      libkrb5
      libssh2
      libtool
      libunistring
      m4
      nghttp2
      ninja
      openbsm
      openldap
      openpam
      openssh
      openssl
      patchutils
      pbzx
      perl
      pkg-config.pkg-config
      python3
      python3Minimal
      scons
      serf
      sqlite
      subversion
      sysctl.provider
      texinfo
      unzip
      which
      xz
      zstd
    ]);

    assert lib.all isBuiltByNixpkgsCompiler (with prevStage; [
      bash
      binutils-unwrapped
      icu
      libffi
      libiconv
      libxml2
      zlib
    ]);

    assert lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.darwin; [ locale print-reexports rewrite-tbd sigtool ]);
    assert lib.all isBuiltByNixpkgsCompiler
      (with prevStage.darwin; [ binutils-unwrapped cctools libtapi ]);

    assert (!useAppleSDKLibs) -> lib.all isBuiltByBootstrapFilesCompiler
      (with prevStage.darwin; [ configd ]);
    assert (!useAppleSDKLibs) -> lib.all isBuiltByNixpkgsCompiler
      (with prevStage.darwin; [ Libsystem ]);
    assert (!useAppleSDKLibs)
      -> lib.all isFromNixpkgs (with prevStage.darwin; [ CF ]);
    assert useAppleSDKLibs -> lib.all isFromNixpkgs
      (with prevStage.darwin; [ CF Libsystem libobjc ]);
    assert lib.all isFromNixpkgs
      (with prevStage.darwin; [ dyld launchd libclosure libdispatch xnu ]);

    assert lib.all isBuiltByNixpkgsCompiler (with prevStage.llvmPackages; [
      clang-unwrapped
      libclang
      libllvm
      llvm
      compiler-rt
      libcxx
    ]);

    assert lib.getVersion prevStage.stdenv.cc.bintools.bintools
      == lib.getVersion prevStage.darwin.cctools-llvm;

    stageFun prevStage {

      name = "bootstrap-stage4";

      overrides = self: super: {
        inherit (prevStage)
          ccWrapperStdenv autoconf automake bash bison cmake cmakeMinimal
          cyrus_sasl db expat flex groff libedit libtool m4 ninja openldap
          openssh patchutils perl pkg-config python3 scons serf sqlite
          subversion sysctl texinfo unzip which

          # CF dependencies - don’t rebuild them.
          icu

          # LLVM dependencies - don’t rebuild them.
          libffi libiconv libxml2 ncurses zlib;

        darwin = super.darwin.overrideScope (selfDarwin: superDarwin: {
          inherit (prevStage.darwin)
            dyld CF Libsystem darwin-stubs
            # CF dependencies - don’t rebuild them.
            libobjc objc4;

          apple_sdk = superDarwin.apple_sdk // {
            inherit (prevStage.darwin.apple_sdk) sdkRoot;
          };

          signingUtils =
            superDarwin.signingUtils.override { inherit (selfDarwin) sigtool; };

          binutils = superDarwin.binutils.override {
            inherit (prevStage) expand-response-params;

            bintools = selfDarwin.binutils-unwrapped;
            libc = selfDarwin.Libsystem;
          };

          # cctools needs to build the LLVM man pages, which requires sphinx. Sphinx
          # has hatch-vcs as a transitive dependency, which pulls in git (and curl).
          # Disabling the tests for hatch-vcs allows the stdenv bootstrap to avoid having
          # any dependency on curl other than the one provided in the bootstrap tools.
          cctools-llvm = superDarwin.cctools-llvm.override (old: {
            llvmPackages = let
              tools = old.llvmPackages.tools.extend (_: superTools: {
                llvm-manpages = superTools.llvm-manpages.override {
                  python3Packages = prevStage.python3Packages.overrideScope
                    (_: superPython: {
                      hatch-vcs = (superPython.hatch-vcs.override {
                        git = null;
                        pytestCheckHook = null;
                      });
                    });
                };
              });
              inherit (old.llvmPackages) libraries release_version;
            in {
              inherit tools libraries release_version;
            } // tools // libraries;
          });
        });

        llvmPackages = super.llvmPackages // (let
          tools = super.llvmPackages.tools.extend (_: _: {
            inherit (prevStage.llvmPackages)
              clang-unwrapped libclang libllvm llvm;
            libcxxClang =
              lib.makeOverridable (import ../../build-support/cc-wrapper) {
                nativeTools = false;
                nativeLibc = false;

                inherit (prevStage) expand-response-params;

                extraPackages = [ self.llvmPackages.compiler-rt ];

                extraBuildCommands = let
                  inherit (self.llvmPackages)
                    clang-unwrapped compiler-rt release_version;

                  # Clang 16+ uses only the major version in resource-root, but older versions use the complete one.
                  clangResourceRootIncludePath = clangLib: clangRelease:
                    let
                      clangVersion =
                        if lib.versionAtLeast clangRelease "16" then
                          lib.versions.major clangRelease
                        else
                          clangRelease;
                    in "${clangLib}/lib/clang/${clangVersion}/include";
                in ''
                  rsrc="$out/resource-root"
                  mkdir "$rsrc"
                  ln -s "${
                    clangResourceRootIncludePath clang-unwrapped.lib
                    release_version
                  }" "$rsrc"
                  ln -s "${compiler-rt.out}/lib"   "$rsrc/lib"
                  ln -s "${compiler-rt.out}/share" "$rsrc/share"
                  echo "-resource-dir=$rsrc" >> $out/nix-support/cc-cflags
                '';

                cc = self.llvmPackages.clang-unwrapped;
                bintools = self.darwin.binutils;

                isClang = true;
                libc = self.darwin.Libsystem;
                inherit (self.llvmPackages) libcxx;

                inherit lib;
                inherit (self) stdenvNoCC coreutils gnugrep runtimeShell;
              };
          });
          libraries = super.llvmPackages.libraries.extend
            (_: _: { inherit (prevStage.llvmPackages) compiler-rt libcxx; });
        in { inherit tools libraries; } // tools // libraries);
      };

      extraNativeBuildInputs = lib.optionals localSystem.isAarch64 [
        prevStage.updateAutotoolsGnuConfigScriptsHook
        prevStage.gnu-config
      ];

      extraPreHook = ''
        stripDebugFlags="-S" # llvm-strip does not support "-p" for Mach-O
      '';
    })

  # Construct the final stdenv. The version of LLVM provided should match the one defined in
  # `all-packages.nix` for Darwin. Nothing should depend on the bootstrap tools or originate from
  # the bootstrap tools.
  #
  # When updating the Darwin stdenv, make sure that the result has no dependency (`nix-store -qR`)
  # on `bootstrapTools` or the binutils built in stage 1.
  (prevStage:
    # previous stage4 stdenv:
    assert lib.all isBuiltByNixpkgsCompiler (with prevStage; [
      bash
      binutils-unwrapped
      brotli
      bzip2
      cpio
      diffutils
      ed
      file
      findutils
      gawk
      gettext
      gmp
      gnugrep
      gnumake
      gnused
      gnutar
      gzip
      icu
      libffi
      libiconv
      libidn2
      libkrb5
      libssh2
      libunistring
      libxml2
      libyaml
      ncurses
      nghttp2
      openbsm
      openpam
      openssl
      patch
      pbzx
      pcre
      python3Minimal
      xar
      xz
      zlib
      zstd
    ]);

    assert lib.all isBuiltByNixpkgsCompiler (with prevStage.darwin; [
      binutils-unwrapped
      cctools
      libtapi
      locale
      print-reexports
      rewrite-tbd
      sigtool
    ]);

    assert (!useAppleSDKLibs) -> lib.all isBuiltByNixpkgsCompiler
      (with prevStage.darwin; [ Libsystem configd ]);
    assert (!useAppleSDKLibs)
      -> lib.all isFromNixpkgs (with prevStage.darwin; [ CF ]);
    assert useAppleSDKLibs -> lib.all isFromNixpkgs
      (with prevStage.darwin; [ CF Libsystem libobjc ]);
    assert lib.all isFromNixpkgs
      (with prevStage.darwin; [ dyld launchd libclosure libdispatch xnu ]);

    assert lib.all isBuiltByNixpkgsCompiler (with prevStage.llvmPackages; [
      clang-unwrapped
      libclang
      libllvm
      llvm
      compiler-rt
      libcxx
    ]);

    assert lib.all isBuiltByBootstrapFilesCompiler (with prevStage; [
      autoconf
      automake
      bison
      cmake
      cmakeMinimal
      cyrus_sasl
      db
      expat
      flex
      groff
      libedit
      libtool
      m4
      ninja
      openldap
      openssh
      patchutils
      perl
      pkg-config.pkg-config
      python3
      scons
      serf
      sqlite
      subversion
      sysctl.provider
      texinfo
      unzip
      which
    ]);

    assert prevStage.darwin.cctools == prevStage.darwin.cctools-llvm;

    let
      doSign = localSystem.isAarch64;

      cc = prevStage.llvmPackages.clang;
    in {
      inherit config overlays;
      stdenv = import ../generic lib {
        name = "stdenv-darwin";

        buildPlatform = localSystem;
        hostPlatform = localSystem;
        targetPlatform = localSystem;

        inherit config;

        preHook = ''
          ${commonPreHook}
          stripDebugFlags="-S" # llvm-strip does not support "-p" for Mach-O
          export PATH_LOCALE=${prevStage.darwin.locale}/share/locale
        '';

        initialPath =
          ((import ../generic/common-path.nix) { pkgs = prevStage; });

        extraNativeBuildInputs = lib.optionals localSystem.isAarch64
          [ prevStage.updateAutotoolsGnuConfigScriptsHook ]
          ++ [ prevStage.darwin.apple_sdk.sdkRoot ];

        extraBuildInputs = [ prevStage.darwin.CF ];

        inherit cc;

        shell = cc.shell;

        inherit (prevStage.stdenv) fetchurlBoot;

        extraAttrs = {
          inherit bootstrapTools;
          libc = prevStage.darwin.Libsystem;
          shellPackage = prevStage.bash;
        } // lib.optionalAttrs useAppleSDKLibs {
          # This objc4 will be propagated to all builds using the final stdenv,
          # and we shouldn't mix different builds, because they would be
          # conflicting LLVM modules. Export it here so we can grab it later.
          inherit (prevStage.darwin) objc4;
        };

        disallowedRequisites = [ bootstrapTools.out ];

        allowedRequisites = (with prevStage;
          [
            bash
            binutils.bintools
            binutils.bintools.lib
            bzip2.bin
            bzip2.out
            cc.expand-response-params
            coreutils
            darwin.binutils
            darwin.binutils.bintools
            diffutils
            ed
            file
            findutils
            gawk
            gettext
            gmp.out
            gnugrep
            gnugrep.pcre2.out
            gnumake
            gnused
            gnutar
            gzip
            icu.out
            libffi.out
            libiconv
            libunistring.out
            libxml2.out
            ncurses.dev
            ncurses.man
            ncurses.out
            openbsm
            openpam
            patch
            xz.bin
            xz.out
            zlib.dev
            zlib.out
          ] ++ lib.optionals doSign [ openssl.out ])
          ++ lib.optionals localSystem.isAarch64 [
            prevStage.updateAutotoolsGnuConfigScriptsHook
            prevStage.gnu-config
          ] ++ (with prevStage.llvmPackages; [
            bintools-unwrapped
            clang-unwrapped
            clang-unwrapped.lib
            compiler-rt
            compiler-rt.dev
            libcxx
            libcxx.dev
            lld
            llvm
            llvm.lib
          ]) ++ (with prevStage.darwin;
            [
              CF
              Libsystem
              cctools-llvm
              cctools-port
              dyld
              libtapi
              locale
              apple_sdk.sdkRoot
            ] ++ lib.optional useAppleSDKLibs [ objc4 ]
            ++ lib.optionals doSign [ postLinkSignHook sigtool signingUtils ]);

        __stdenvImpureHostDeps = commonImpureHostDeps;
        __extraImpureHostDeps = commonImpureHostDeps;

        overrides = self: super:
          {
            inherit (prevStage)
              bash binutils brotli bzip2 coreutils cpio diffutils ed file
              findutils gawk gettext gmp gnugrep gnumake gnused gnutar gzip icu
              libffi libiconv libidn2 libssh2 libunistring libxml2 libyaml
              ncurses nghttp2 openbsm openpam openssl patch pbzx pcre
              python3Minimal xar xz zlib zstd;

            darwin = super.darwin.overrideScope (_: superDarwin:
              {
                inherit (prevStage.darwin)
                  CF ICU Libsystem darwin-stubs dyld locale libobjc libtapi
                  rewrite-tbd xnu;

                apple_sdk = superDarwin.apple_sdk // {
                  inherit (prevStage.darwin.apple_sdk) sdkRoot;
                };
              } // lib.optionalAttrs
              (super.stdenv.targetPlatform == localSystem) {
                inherit (prevStage.darwin)
                  binutils binutils-unwrapped cctools-llvm cctools-port;
              });
          } // lib.optionalAttrs (super.stdenv.targetPlatform == localSystem) {
            inherit (prevStage.llvmPackages) clang llvm;

            # Need to get rid of these when cross-compiling.
            llvmPackages = super.llvmPackages // (let
              tools = super.llvmPackages.tools.extend (_: _: {
                inherit (prevStage.llvmPackages)
                  clang clang-unwrapped libclang libllvm llvm;
              });
              libraries = super.llvmPackages.libraries.extend (_: _: {
                inherit (prevStage.llvmPackages) compiler-rt libcxx;
              });
            in { inherit tools libraries; } // tools // libraries);

            inherit (prevStage) binutils binutils-unwrapped;
          };
      };
    })

  # This "no-op" stage is just a place to put the assertions about stage6.
  (prevStage:
    # previous final stage stdenv:
    assert isBuiltByNixpkgsCompiler prevStage.darwin.sigtool;
    assert isBuiltByNixpkgsCompiler prevStage.darwin.binutils-unwrapped;
    assert isBuiltByNixpkgsCompiler prevStage.darwin.print-reexports;
    assert isBuiltByNixpkgsCompiler prevStage.darwin.rewrite-tbd;
    assert isBuiltByNixpkgsCompiler prevStage.darwin.cctools;

    assert isFromNixpkgs prevStage.darwin.CF;
    assert isFromNixpkgs prevStage.darwin.Libsystem;

    assert isBuiltByNixpkgsCompiler prevStage.llvmPackages.clang-unwrapped;
    assert isBuiltByNixpkgsCompiler prevStage.llvmPackages.libllvm;
    assert isBuiltByNixpkgsCompiler prevStage.llvmPackages.libcxx;
    assert isBuiltByNixpkgsCompiler prevStage.llvmPackages.compiler-rt; {
      inherit (prevStage) config overlays stdenv;
    })
]