{ lib, stdenv, pkgsBuildTarget, pkgsHostTarget, buildPackages, targetPackages

# build-tools
, bootPkgs
, autoreconfHook, autoconf, automake, coreutils, fetchpatch, fetchurl, perl, python3, m4, sphinx
, xattr, autoSignDarwinBinariesHook
, bash

, libiconv ? null, ncurses

, # GHC can be built with system libffi or a bundled one.
  # we explicitly use libffi-3.3 here because 3.4 removes a flag that causes
  # problems for ghc-8.10.7's RTS. See #324384.
  # Save for aarch_darwin since libffi-3.3 is broken there but the issue isn't present anyway
  libffi ? null
, libffi_3_3 ? null

, useLLVM ? !(stdenv.targetPlatform.isx86
              || stdenv.targetPlatform.isPower
              || stdenv.targetPlatform.isSparc)
, # LLVM is conceptually a run-time-only dependency, but for
  # non-x86, we need LLVM to bootstrap later stages, so it becomes a
  # build-time dependency too.
  buildTargetLlvmPackages, llvmPackages

, # If enabled, GHC will be built with the GPL-free but slower integer-simple
  # library instead of the faster but GPLed integer-gmp library.
  enableIntegerSimple ? !(lib.meta.availableOn stdenv.hostPlatform gmp
                          && lib.meta.availableOn stdenv.targetPlatform gmp)
, gmp

, # If enabled, use -fPIC when compiling static libs.
  enableRelocatedStaticLibs ? stdenv.targetPlatform != stdenv.hostPlatform

  # Exceeds Hydra output limit (at the time of writing ~3GB) when cross compiled to riscv64.
  # A riscv64 cross-compiler fits into the limit comfortably.
, enableProfiledLibs ? !stdenv.hostPlatform.isRiscV64

, # Whether to build dynamic libs for the standard library (on the target
  # platform). Static libs are always built.
  enableShared ? !stdenv.targetPlatform.isWindows && !stdenv.targetPlatform.useiOSPrebuilt

, # Whether to build terminfo.
  enableTerminfo ? !(stdenv.targetPlatform.isWindows
                     # terminfo can't be built for cross
                     || (stdenv.buildPlatform != stdenv.hostPlatform)
                     || (stdenv.hostPlatform != stdenv.targetPlatform))

, # What flavour to build. An empty string indicates no
  # specific flavour and falls back to ghc default values.
  ghcFlavour ? lib.optionalString (stdenv.targetPlatform != stdenv.hostPlatform)
    (if useLLVM then "perf-cross" else "perf-cross-ncg")

, #  Whether to build sphinx documentation.
  enableDocs ? (
    # Docs disabled if we are building on musl because it's a large task to keep
    # all `sphinx` dependencies building in this environment.
    !stdenv.buildPlatform.isMusl
  )

, enableHaddockProgram ?
    # Disabled for cross; see note [HADDOCK_DOCS].
    (stdenv.buildPlatform == stdenv.hostPlatform && stdenv.targetPlatform == stdenv.hostPlatform)

, # Whether to disable the large address space allocator
  # necessary fix for iOS: https://www.reddit.com/r/haskell/comments/4ttdz1/building_an_osxi386_to_iosarm64_cross_compiler/d5qvd67/
  disableLargeAddressSpace ? stdenv.targetPlatform.isiOS

, # Whether to build an unregisterised version of GHC.
  # GHC will normally auto-detect whether it can do a registered build, but this
  # option will force it to do an unregistered build when set to true.
  # See https://gitlab.haskell.org/ghc/ghc/-/wikis/building/unregisterised
  enableUnregisterised ? false
}@args:

assert !enableIntegerSimple -> gmp != null;

# Cross cannot currently build the `haddock` program for silly reasons,
# see note [HADDOCK_DOCS].
assert (stdenv.buildPlatform != stdenv.hostPlatform || stdenv.targetPlatform != stdenv.hostPlatform) -> !enableHaddockProgram;

# GHC does not support building when all 3 platforms are different.
assert stdenv.buildPlatform == stdenv.hostPlatform || stdenv.hostPlatform == stdenv.targetPlatform;

let
  inherit (stdenv) buildPlatform hostPlatform targetPlatform;

  # TODO(@Ericson2314) Make unconditional
  targetPrefix = lib.optionalString
    (targetPlatform != hostPlatform)
    "${targetPlatform.config}-";

  buildMK = ''
    BuildFlavour = ${ghcFlavour}
    ifneq \"\$(BuildFlavour)\" \"\"
    include mk/flavours/\$(BuildFlavour).mk
    endif
    BUILD_SPHINX_HTML = ${if enableDocs then "YES" else "NO"}
    BUILD_SPHINX_PDF = NO

    WITH_TERMINFO = ${if enableTerminfo then "YES" else "NO"}
  '' +
  # Note [HADDOCK_DOCS]:
  # Unfortunately currently `HADDOCK_DOCS` controls both whether the `haddock`
  # program is built (which we generally always want to have a complete GHC install)
  # and whether it is run on the GHC sources to generate hyperlinked source code
  # (which is impossible for cross-compilation); see:
  # https://gitlab.haskell.org/ghc/ghc/-/issues/20077
  # This implies that currently a cross-compiled GHC will never have a `haddock`
  # program, so it can never generate haddocks for any packages.
  # If this is solved in the future, we'd like to unconditionally
  # build the haddock program (removing the `enableHaddockProgram` option).
  ''
    HADDOCK_DOCS = ${if enableHaddockProgram then "YES" else "NO"}
    # Build haddocks for boot packages with hyperlinking
    EXTRA_HADDOCK_OPTS += --hyperlinked-source --quickjump

    DYNAMIC_GHC_PROGRAMS = ${if enableShared then "YES" else "NO"}
    INTEGER_LIBRARY = ${if enableIntegerSimple then "integer-simple" else "integer-gmp"}
  '' + lib.optionalString (targetPlatform != hostPlatform) ''
    Stage1Only = ${if targetPlatform.system == hostPlatform.system then "NO" else "YES"}
    CrossCompilePrefix = ${targetPrefix}
  '' + lib.optionalString (!enableProfiledLibs) ''
    BUILD_PROF_LIBS = NO
  '' + lib.optionalString enableRelocatedStaticLibs ''
    GhcLibHcOpts += -fPIC
    GhcRtsHcOpts += -fPIC
  '' + lib.optionalString targetPlatform.useAndroidPrebuilt ''
    EXTRA_CC_OPTS += -std=gnu99
  ''
  # While split sections are now enabled by default in ghc 8.8 for windows,
  # they seem to lead to `too many sections` errors when building base for
  # profiling.
  + lib.optionalString targetPlatform.isWindows ''
    SplitSections = NO
  '';

  # Splicer will pull out correct variations
  libDeps = platform: lib.optional enableTerminfo ncurses
    ++ [args.${libffi_name}]
    ++ lib.optional (!enableIntegerSimple) gmp
    ++ lib.optional (platform.libc != "glibc" && !targetPlatform.isWindows) libiconv;

  # TODO(@sternenseemann): is buildTarget LLVM unnecessary?
  # GHC doesn't seem to have {LLC,OPT}_HOST
  toolsForTarget = [
    pkgsBuildTarget.targetPackages.stdenv.cc
  ] ++ lib.optional useLLVM buildTargetLlvmPackages.llvm;

  buildCC = buildPackages.stdenv.cc;
  targetCC = builtins.head toolsForTarget;
  installCC = pkgsHostTarget.targetPackages.stdenv.cc;

  # toolPath calculates the absolute path to the name tool associated with a
  # given `stdenv.cc` derivation, i.e. it picks the correct derivation to take
  # the tool from (cc, cc.bintools, cc.bintools.bintools) and adds the correct
  # subpath of the tool.
  toolPath = name: cc:
    let
      tools = {
        "cc" = cc;
        "c++" = cc;
        as = cc.bintools;

        ar = cc.bintools;
        ranlib = cc.bintools;
        nm = cc.bintools;
        readelf = cc.bintools;
        objdump = cc.bintools;

        ld = cc.bintools;
        "ld.gold" = cc.bintools;

        otool = cc.bintools.bintools;

        # GHC needs install_name_tool on all darwin platforms. The same one can
        # be used on both platforms. It is safe to use with linker-generated
        # signatures because it will update the signatures automatically after
        # modifying the target binary.
        install_name_tool = cc.bintools.bintools;

        # strip on darwin is wrapped to enable deterministic mode.
        strip =
          # TODO(@sternenseemann): also use wrapper if linker == "bfd" or "gold"
          if stdenv.targetPlatform.isDarwin
          then cc.bintools
          else cc.bintools.bintools;

        # clang is used as an assembler on darwin with the LLVM backend
        clang = cc;
      }.${name};
    in
    "${tools}/bin/${tools.targetPrefix}${name}";

  # Use gold either following the default, or to avoid the BFD linker due to some bugs / perf issues.
  # But we cannot avoid BFD when using musl libc due to https://sourceware.org/bugzilla/show_bug.cgi?id=23856
  # see #84670 and #49071 for more background.
  useLdGold = targetPlatform.linker == "gold" ||
    (targetPlatform.linker == "bfd" && (targetCC.bintools.bintools.hasGold or false) && !targetPlatform.isMusl);

  # Makes debugging easier to see which variant is at play in `nix-store -q --tree`.
  variantSuffix = lib.concatStrings [
    (lib.optionalString stdenv.hostPlatform.isMusl "-musl")
    (lib.optionalString enableIntegerSimple "-integer-simple")
  ];

  libffi_name =
    if stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isAarch64
    then "libffi"
    else "libffi_3_3";

  # These libraries are library dependencies of the standard libraries bundled
  # by GHC (core libs) users will link their compiled artifacts again. Thus,
  # they should be taken from targetPackages.
  #
  # We need to use pkgsHostTarget if we are cross compiling a native GHC compiler,
  # though (when native compiling GHC, pkgsHostTarget == targetPackages):
  #
  # 1. targetPackages would be empty(-ish) in this situation since we can't
  #    execute cross compiled compilers in order to obtain the libraries
  #    that would be in targetPackages.
  # 2. pkgsHostTarget is fine to use since hostPlatform == targetPlatform in this
  #    situation.
  # 3. The core libs used by the final GHC (stage 2) for user artifacts are also
  #    used to build stage 2 GHC itself, i.e. the core libs are both host and
  #    target.
  targetLibs =
    let
      basePackageSet =
        if hostPlatform != targetPlatform
        then targetPackages
        else pkgsHostTarget;
    in
      {
        inherit (basePackageSet) gmp ncurses;
        # dynamic inherits are not possible in Nix
        libffi = basePackageSet.${libffi_name};
      };

in

stdenv.mkDerivation (rec {
  version = "8.10.7";
  pname = "${targetPrefix}ghc${variantSuffix}";

  src = fetchurl {
    url = "https://downloads.haskell.org/ghc/${version}/ghc-${version}-src.tar.xz";
    sha256 = "e3eef6229ce9908dfe1ea41436befb0455fefb1932559e860ad4c606b0d03c9d";
  };

  enableParallelBuilding = true;

  outputs = [ "out" "doc" ];

  patches = [
    # Fix docs build with sphinx >= 6.0
    # https://gitlab.haskell.org/ghc/ghc/-/issues/22766
    (fetchpatch {
      name = "ghc-docs-sphinx-6.0.patch";
      url = "https://gitlab.haskell.org/ghc/ghc/-/commit/10e94a556b4f90769b7fd718b9790d58ae566600.patch";
      sha256 = "0kmhfamr16w8gch0lgln2912r8aryjky1hfcda3jkcwa5cdzgjdv";
    })

    # See upstream patch at
    # https://gitlab.haskell.org/ghc/ghc/-/merge_requests/4885. Since we build
    # from source distributions, the auto-generated configure script needs to be
    # patched as well, therefore we use an in-tree patch instead of pulling the
    # upstream patch. Don't forget to check backport status of the upstream patch
    # when adding new GHC releases in nixpkgs.
    ./respect-ar-path.patch

    # fix hyperlinked haddock sources: https://github.com/haskell/haddock/pull/1482
    (fetchpatch {
      url = "https://patch-diff.githubusercontent.com/raw/haskell/haddock/pull/1482.patch";
      sha256 = "sha256-8w8QUCsODaTvknCDGgTfFNZa8ZmvIKaKS+2ZJZ9foYk=";
      extraPrefix = "utils/haddock/";
      stripLen = 1;
    })

    # cabal passes incorrect --host= when cross-compiling
    # https://github.com/haskell/cabal/issues/5887
    (fetchpatch {
            url = "https://raw.githubusercontent.com/input-output-hk/haskell.nix/122bd81150386867da07fdc9ad5096db6719545a/overlays/patches/ghc/cabal-host.patch";
      sha256 = "sha256:0yd0sajgi24sc1w5m55lkg2lp6kfkgpp3lgija2c8y3cmkwfpdc1";
    })

    # In order to build ghcjs packages, the Cabal of the ghc used for the ghcjs
    # needs to be patched. Ref https://github.com/haskell/cabal/pull/7575
    (fetchpatch {
      url = "https://github.com/haskell/cabal/commit/369c4a0a54ad08a9e6b0d3bd303fedd7b5e5a336.patch";
      sha256 = "120f11hwyaqa0pq9g5l1300crqij49jg0rh83hnp9sa49zfdwx1n";
      stripLen = 3;
      extraPrefix = "libraries/Cabal/Cabal/";
    })

    # We need to be able to set AR_STAGE0 and LD_STAGE0 when cross-compiling
    (fetchpatch {
      url = "https://gitlab.haskell.org/ghc/ghc/-/commit/8f7dd5710b80906ea7a3e15b7bb56a883a49fed8.patch";
      hash = "sha256-C636Nq2U8YOG/av7XQmG3L1rU0bmC9/7m7Hty5pm5+s=";
    })

    # Backport part of <https://gitlab.haskell.org/ghc/ghc/-/merge_requests/7111> to 8.10.7
    # The change we are interested in is that Cabal no longer sets include-dirs
    # for the GHCi library delegating to the system search path or (in our case)
    # cc-wrapper. Without this patch, the target libffi ends up in there (which
    # we provide via --with-ffi-includes) which breaks bootstrapping e.g. when
    # cross compiling GHC. Without include-dirs, cc-wrapper and splicing will
    # correctly pick the suitable libffi out of the build environment.
    (fetchpatch {
      name = "ghci-no-libffi-include.patch";
      url = "https://gitlab.haskell.org/ghc/ghc/-/commit/b2721819f391ab49871271283f32df54810c4387.patch";
      sha256 = "1rmv3132xhxbka97v0rx7r6larx5f5nnvs4mgm9q3rmgpjyd1vf9";
      includes = [ "libraries/ghci/ghci.cabal.in" ];
    })
  ] ++ lib.optionals stdenv.hostPlatform.isDarwin [
    # Make Block.h compile with c++ compilers. Remove with the next release
    (fetchpatch {
      url = "https://gitlab.haskell.org/ghc/ghc/-/commit/97d0b0a367e4c6a52a17c3299439ac7de129da24.patch";
      sha256 = "0r4zjj0bv1x1m2dgxp3adsf2xkr94fjnyj1igsivd9ilbs5ja0b5";
    })
  ] ++ lib.optionals (stdenv.targetPlatform.isDarwin && stdenv.targetPlatform.isAarch64) [
    # Prevent the paths module from emitting symbols that we don't use
    # when building with separate outputs.
    #
    # These cause problems as they're not eliminated by GHC's dead code
    # elimination on aarch64-darwin. (see
    # https://github.com/NixOS/nixpkgs/issues/140774 for details).
    ./Cabal-3.2-3.4-paths-fix-cycle-aarch64-darwin.patch
  ];

  postPatch = "patchShebangs .";

  # GHC is a bit confused on its cross terminology.
  # TODO(@sternenseemann): investigate coreutils dependencies and pass absolute paths
  preConfigure = ''
    for env in $(env | grep '^TARGET_' | sed -E 's|\+?=.*||'); do
      export "''${env#TARGET_}=''${!env}"
    done
    # Stage0 (build->build) which builds stage 1
    export GHC="${bootPkgs.ghc}/bin/ghc"
    # GHC is a bit confused on its cross terminology, as these would normally be
    # the *host* tools.
    export CC="${toolPath "cc" targetCC}"
    export CXX="${toolPath "c++" targetCC}"
    # Use gold to work around https://sourceware.org/bugzilla/show_bug.cgi?id=16177
    export LD="${toolPath "ld${lib.optionalString useLdGold ".gold"}" targetCC}"
    export AS="${toolPath "as" targetCC}"
    export AR="${toolPath "ar" targetCC}"
    export NM="${toolPath "nm" targetCC}"
    export RANLIB="${toolPath "ranlib" targetCC}"
    export READELF="${toolPath "readelf" targetCC}"
    export STRIP="${toolPath "strip" targetCC}"
    export OBJDUMP="${toolPath "objdump" targetCC}"
  '' + lib.optionalString (stdenv.targetPlatform.linker == "cctools") ''
    export OTOOL="${toolPath "otool" targetCC}"
    export INSTALL_NAME_TOOL="${toolPath "install_name_tool" targetCC}"
  '' + lib.optionalString useLLVM ''
    export LLC="${lib.getBin buildTargetLlvmPackages.llvm}/bin/llc"
    export OPT="${lib.getBin buildTargetLlvmPackages.llvm}/bin/opt"
  '' + lib.optionalString (useLLVM && stdenv.targetPlatform.isDarwin) ''
    # LLVM backend on Darwin needs clang: https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/codegens.html#llvm-code-generator-fllvm
    # The executable we specify via $CLANG is used as an assembler (exclusively, it seems, but this isn't
    # clarified in any user facing documentation). As such, it'll be called on assembly produced by $CC
    # which usually comes from the darwin stdenv. To prevent a situation where $CLANG doesn't understand
    # the assembly it is given, we need to make sure that it matches the LLVM version of $CC if possible.
    # It is unclear (at the time of writing 2024-09-01)  whether $CC should match the LLVM version we use
    # for llc and opt which would require using a custom darwin stdenv for targetCC.
    export CLANG="${
      if targetCC.isClang
      then toolPath "clang" targetCC
      else "${buildTargetLlvmPackages.clang}/bin/${buildTargetLlvmPackages.clang.targetPrefix}clang"
    }"
  '' + ''
    # No need for absolute paths since these tools only need to work during the build
    export CC_STAGE0="$CC_FOR_BUILD"
    export LD_STAGE0="$LD_FOR_BUILD"
    export AR_STAGE0="$AR_FOR_BUILD"

    echo -n "${buildMK}" > mk/build.mk
    sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
  '' + lib.optionalString (!stdenv.hostPlatform.isDarwin) ''
    export NIX_LDFLAGS+=" -rpath $out/lib/ghc-${version}"
  '' + lib.optionalString stdenv.hostPlatform.isDarwin ''
    export NIX_LDFLAGS+=" -no_dtrace_dof"

    # GHC tries the host xattr /usr/bin/xattr by default which fails since it expects python to be 2.7
    export XATTR=${lib.getBin xattr}/bin/xattr
  '' + lib.optionalString targetPlatform.useAndroidPrebuilt ''
    sed -i -e '5i ,("armv7a-unknown-linux-androideabi", ("e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64", "cortex-a8", ""))' llvm-targets
  '' + lib.optionalString targetPlatform.isMusl ''
      echo "patching llvm-targets for musl targets..."
      echo "Cloning these existing '*-linux-gnu*' targets:"
      grep linux-gnu llvm-targets | sed 's/^/  /'
      echo "(go go gadget sed)"
      sed -i 's,\(^.*linux-\)gnu\(.*\)$,\0\n\1musl\2,' llvm-targets
      echo "llvm-targets now contains these '*-linux-musl*' targets:"
      grep linux-musl llvm-targets | sed 's/^/  /'

      echo "And now patching to preserve '-musleabi' as done with '-gnueabi'"
      # (aclocal.m4 is actual source, but patch configure as well since we don't re-gen)
      for x in configure aclocal.m4; do
        substituteInPlace $x \
          --replace '*-android*|*-gnueabi*)' \
                    '*-android*|*-gnueabi*|*-musleabi*)'
      done
  '';

  # Although it is usually correct to pass --host, we don't do that here because
  # GHC's usage of build, host, and target is non-standard.
  # See https://gitlab.haskell.org/ghc/ghc/-/wikis/building/cross-compiling
  # TODO(@Ericson2314): Always pass "--target" and always prefix.
  configurePlatforms = [ "build" ]
    ++ lib.optional (buildPlatform != hostPlatform || targetPlatform != hostPlatform) "target";

  # `--with` flags for libraries needed for RTS linker
  configureFlags = [
    "--datadir=$doc/share/doc/ghc"
  ] ++ lib.optionals enableTerminfo [
    "--with-curses-includes=${lib.getDev targetLibs.ncurses}/include"
    "--with-curses-libraries=${lib.getLib targetLibs.ncurses}/lib"
  ] ++ lib.optionals (args.${libffi_name} != null) [
    "--with-system-libffi"
    "--with-ffi-includes=${targetLibs.libffi.dev}/include"
    "--with-ffi-libraries=${targetLibs.libffi.out}/lib"
  ] ++ lib.optionals (targetPlatform == hostPlatform && !enableIntegerSimple) [
    "--with-gmp-includes=${targetLibs.gmp.dev}/include"
    "--with-gmp-libraries=${targetLibs.gmp.out}/lib"
  ] ++ lib.optionals (targetPlatform == hostPlatform && hostPlatform.libc != "glibc" && !targetPlatform.isWindows) [
    "--with-iconv-includes=${libiconv}/include"
    "--with-iconv-libraries=${libiconv}/lib"
  ] ++ lib.optionals (targetPlatform != hostPlatform) [
    "--enable-bootstrap-with-devel-snapshot"
  ] ++ lib.optionals useLdGold [
    "CFLAGS=-fuse-ld=gold"
    "CONF_GCC_LINKER_OPTS_STAGE1=-fuse-ld=gold"
    "CONF_GCC_LINKER_OPTS_STAGE2=-fuse-ld=gold"
  ] ++ lib.optionals (disableLargeAddressSpace) [
    "--disable-large-address-space"
  ] ++ lib.optionals enableUnregisterised [
    "--enable-unregisterised"
  ];

  # Make sure we never relax`$PATH` and hooks support for compatibility.
  strictDeps = true;

  # Don’t add -liconv to LDFLAGS automatically so that GHC will add it itself.
  dontAddExtraLibs = true;

  nativeBuildInputs = [
    perl autoreconfHook autoconf automake m4 python3
    bootPkgs.alex bootPkgs.happy bootPkgs.hscolour
    bootPkgs.ghc-settings-edit
  ] ++ lib.optionals (stdenv.hostPlatform.isDarwin && stdenv.hostPlatform.isAarch64) [
    autoSignDarwinBinariesHook
  ] ++ lib.optionals enableDocs [
    sphinx
  ];

  # Everything the stage0 compiler needs to build stage1: CC, bintools, extra libs.
  # See also GHC, {CC,LD,AR}_STAGE0 in preConfigure.
  depsBuildBuild = [
    # N.B. We do not declare bootPkgs.ghc in any of the stdenv.mkDerivation
    # dependency lists to prevent the bintools setup hook from adding ghc's
    # lib directory to the linker flags. Instead we tell configure about it
    # via the GHC environment variable.
    buildCC
    # stage0 builds terminfo unconditionally, so we always need ncurses
    ncurses
  ];
  # For building runtime libs
  depsBuildTarget = toolsForTarget;

  # Prevent stage0 ghc from leaking into the final result. This was an issue
  # with GHC 9.6.
  disallowedReferences = [
    bootPkgs.ghc
  ];

  buildInputs = [ bash ] ++ (libDeps hostPlatform);

  depsTargetTarget = map lib.getDev (libDeps targetPlatform);
  depsTargetTargetPropagated = map (lib.getOutput "out") (libDeps targetPlatform);

  # required, because otherwise all symbols from HSffi.o are stripped, and
  # that in turn causes GHCi to abort
  stripDebugFlags = [ "-S" ] ++ lib.optional (!targetPlatform.isDarwin) "--keep-file-symbols";

  checkTarget = "test";

  hardeningDisable =
    [ "format" ]
    # In nixpkgs, musl based builds currently enable `pie` hardening by default
    # (see `defaultHardeningFlags` in `make-derivation.nix`).
    # But GHC cannot currently produce outputs that are ready for `-pie` linking.
    # Thus, disable `pie` hardening, otherwise `recompile with -fPIE` errors appear.
    # See:
    # * https://github.com/NixOS/nixpkgs/issues/129247
    # * https://gitlab.haskell.org/ghc/ghc/-/issues/19580
    ++ lib.optional stdenv.targetPlatform.isMusl "pie";

  # big-parallel allows us to build with more than 2 cores on
  # Hydra which already warrants a significant speedup
  requiredSystemFeatures = [ "big-parallel" ];

  postInstall = ''
    settingsFile="$out/lib/${targetPrefix}${passthru.haskellCompilerName}/settings"

    # Make the installed GHC use the host->target tools.
    ghc-settings-edit "$settingsFile" \
      "C compiler command" "${toolPath "cc" installCC}" \
      "Haskell CPP command" "${toolPath "cc" installCC}" \
      "C++ compiler command" "${toolPath "c++" installCC}" \
      "ld command" "${toolPath "ld${lib.optionalString useLdGold ".gold"}" installCC}" \
      "Merge objects command" "${toolPath "ld${lib.optionalString useLdGold ".gold"}" installCC}" \
      "ar command" "${toolPath "ar" installCC}" \
      "ranlib command" "${toolPath "ranlib" installCC}"
  ''
  + lib.optionalString (stdenv.targetPlatform.linker == "cctools") ''
    ghc-settings-edit "$settingsFile" \
      "otool command" "${toolPath "otool" installCC}" \
      "install_name_tool command" "${toolPath "install_name_tool" installCC}"
  ''
  + lib.optionalString useLLVM ''
    ghc-settings-edit "$settingsFile" \
      "LLVM llc command" "${lib.getBin llvmPackages.llvm}/bin/llc" \
      "LLVM opt command" "${lib.getBin llvmPackages.llvm}/bin/opt"
  ''
  + lib.optionalString (useLLVM && stdenv.targetPlatform.isDarwin) ''
    ghc-settings-edit "$settingsFile" \
      "LLVM clang command" "${
        # See comment for CLANG in preConfigure
        if installCC.isClang
        then toolPath "clang" installCC
        else "${llvmPackages.clang}/bin/${llvmPackages.clang.targetPrefix}clang"
      }"
  ''
  + ''

    # Install the bash completion file.
    install -D -m 444 utils/completion/ghc.bash $out/share/bash-completion/completions/${targetPrefix}ghc
  '';

  passthru = {
    inherit bootPkgs targetPrefix;

    inherit llvmPackages;
    inherit enableShared;

    # This is used by the haskell builder to query
    # the presence of the haddock program.
    hasHaddock = enableHaddockProgram;

    # Our Cabal compiler name
    haskellCompilerName = "ghc-${version}";
  };

  meta = {
    homepage = "http://haskell.org/ghc";
    description = "Glasgow Haskell Compiler";
    maintainers = with lib.maintainers; [
      guibou
    ] ++ lib.teams.haskell.members;
    timeout = 24 * 3600;
    platforms = lib.platforms.all;
    inherit (bootPkgs.ghc.meta) license;
  };

} // lib.optionalAttrs targetPlatform.useAndroidPrebuilt {
  dontStrip = true;
  dontPatchELF = true;
  noAuditTmpdir = true;
})