ci: More surgical use of nix in Darwin builds

6 files changed, 337 insertions, 164 deletions

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 5b7a21b183..d0c5b6315b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -542,6 +542,7 @@ validate-x86_64-darwin:
   allow_failure: true
 
   variables:
+    BUILD_FLAVOUR: "validate"
     GHC_VERSION: 8.10.4
     CABAL_INSTALL_VERSION: 3.2.0.0
     BIN_DIST_PREP_TAR_COMP: "ghc-x86_64-apple-darwin.tar.xz"
@@ -559,55 +560,35 @@ validate-x86_64-darwin:
     CPUS: 8
     LANG: "en_US.UTF-8"
     # WARNING: this is overridden in the shell.nix, see shell.nix!
-    CONFIGURE_ARGS: "--with-intree-gmp"
+    CONFIGURE_ARGS: "--with-intree-gmp --with-system-libffi"
     HADRIAN_ARGS: "--docs=no-sphinx"
     TEST_ENV: "x86_64-darwin-hadrian"
-    BIN_DIST_NAME: "ghc-amd64-apple-darwin"
-    BUILD_FLAVOUR: "validate"
+    BIN_DIST_NAME: "ghc-x86_64-apple-darwin"
+    # Capi_Ctype_001 Capi_Ctype_002 T12010: Due to #20393
+    BROKEN_TESTS: "Capi_Ctype_001 Capi_Ctype_002 T12010"
     # Due to #19025
     IGNORE_PERF_FAILURES: "all"
   after_script:
     - .gitlab/ci.sh clean
     - cat ci-timings
 
-  # I wish we could just use the nix #! logic, but we can't --run and -i bash
-  # behave very differently. -i bash does not pass any nix related env vars
-  # the whole $stdenv/setup part seems to be missing.
   script: |
-    set -Eeuo pipefail
-    function runInNixShell() {
-      time nix-shell .gitlab/shell.nix \
-        -I nixpkgs=https://github.com/angerman/nixpkgs/archive/75f7281738b.tar.gz \
-        --argstr system "x86_64-darwin" \
-        --pure \
-        --keep GHC_VERSION --keep CABAL_INSTALL_VERSION --keep BUILD_FLAVOUR \
-        --keep BIN_DIST_PREP_TAR_COMP --keep CPUS --keep PROJECT_DIR \
-        --keep CI_PROJECT_DIR --keep MAKE_ARGS --keep HADRIAN_ARGS --keep HOME \
-        --keep LANG --keep CONFIGURE_ARGS --keep TEST_ENV --keep BIN_DIST_NAME \
-        --keep MACOSX_DEPLOYMENT_TARGET --keep ac_cv_func_clock_gettime --keep HACKAGE_INDEX_STATE \
-        --keep PERF_NOTE_KEY --keep HEAD_HACKAGE_TRIGGER_TOKEN \
-        --run "$1" 2>&1
-    }
-    # make sure home exists
-    export HOME=$HOME/x86_64-home
-    mkdir -p $HOME
+    nix build -f .gitlab/darwin/toolchain.nix --argstr system x86_64-darwin -o toolchain.sh
+    source toolchain.sh
+    cat toolchain.sh
+
+    sdk_path="$(xcrun --sdk macosx --show-sdk-path)"
+    CONFIGURE_ARGS="$CONFIGURE_ARGS --with-ffi-libraries=$sdk_path/usr/lib --with-ffi-includes=$sdk_path/usr/include/ffi"
 
     # fix up config.sub in libraries for the time.
     # aarch64-darwin is not supported in older config.sub's
     find libraries -name config.sub -exec cp config.sub {} \;
 
-    runInNixShell ".gitlab/ci.sh setup"
-
-    # make sure $HOME is prisine
-    echo "Deleting $HOME/.cabal"
-    rm -fR $HOME/.cabal
-    runInNixShell "cabal update --index=$HACKAGE_INDEX_STATE"
-    runInNixShell ".gitlab/ci.sh configure"
-    runInNixShell ".gitlab/ci.sh build_hadrian"
-    runInNixShell ".gitlab/ci.sh test_hadrian"
-
-    # Important to run this in nix-shell because $HOME is different in there
-    runInNixShell ".gitlab/ci.sh save_cache"
+    .gitlab/ci.sh setup
+    .gitlab/ci.sh configure
+    .gitlab/ci.sh build_hadrian
+    .gitlab/ci.sh test_hadrian
+    .gitlab/ci.sh save_cache
 
   artifacts:
     when: always
@@ -622,11 +603,11 @@ validate-aarch64-darwin:
     - aarch64-darwin-m1
 
   variables:
+    BUILD_FLAVOUR: "validate"
     TEST_TYPE: test
     MAKE_ARGS: "-Werror"
     GHC_VERSION: 8.10.3
     CABAL_INSTALL_VERSION: 3.2.0.0
-    BUILD_FLAVOUR: "perf"
     BIN_DIST_PREP_TAR_COMP: "ghc-arm64-apple-darwin.tar.xz"
     # we run on M1's for now, getconf can't be built with nix yet,
     # and we use a pure shell, so we can't/shouldn't use /usr/bin/getconf
@@ -634,10 +615,12 @@ validate-aarch64-darwin:
     CPUS: 8
     LANG: "en_US.UTF-8"
     # WARNING: this is overridden in the shell.nix, see shell.nix!
-    CONFIGURE_ARGS: "--with-intree-gmp"
+    CONFIGURE_ARGS: "--with-intree-gmp --with-system-libffi"
     HADRIAN_ARGS: "--docs=no-sphinx"
     BIN_DIST_NAME: "ghc-arm64-apple-darwin"
     TEST_ENV: "aarch64-darwin-hadrian"
+    # Capi_Ctype_001 Capi_Ctype_002 T12010: Due to #20393
+    BROKEN_TESTS: "Capi_Ctype_001 Capi_Ctype_002 T12010"
   after_script:
     - .gitlab/ci.sh clean
     - cat ci-timings
@@ -646,39 +629,22 @@ validate-aarch64-darwin:
   # behave very differently. -i bash does not pass any nix related env vars
   # the whole $stdenv/setup part seems to be missing.
   script: |
-    set -Eeuo pipefail
-    function runInNixShell() {
-      time nix-shell .gitlab/shell.nix \
-        -I nixpkgs=https://github.com/angerman/nixpkgs/archive/75f7281738b.tar.gz \
-        --argstr system "aarch64-darwin" \
-        --pure \
-        --keep GHC_VERSION --keep CABAL_INSTALL_VERSION --keep BUILD_FLAVOUR \
-        --keep BIN_DIST_PREP_TAR_COMP --keep CPUS --keep PROJECT_DIR \
-        --keep CI_PROJECT_DIR --keep MAKE_ARGS --keep HADRIAN_ARGS --keep HOME \
-        --keep LANG --keep CONFIGURE_ARGS --keep TEST_ENV --keep BIN_DIST_NAME \
-        --keep HACKAGE_INDEX_STATE \
-        --run "$1" 2>&1
-    }
-    export HOME=$HOME/arm64-home
-    # make sure home exists
-    mkdir -p $HOME
+    nix build -f .gitlab/darwin/toolchain.nix --argstr system aarch64-darwin -o toolchain.sh
+    source toolchain.sh
+    cat toolchain.sh
+
+    sdk_path="$(xcrun --sdk macosx --show-sdk-path)"
+    CONFIGURE_ARGS="$CONFIGURE_ARGS --with-ffi-libraries=$sdk_path/usr/lib --with-ffi-includes=$sdk_path/usr/include/ffi"
 
     # fix up config.sub in libraries for the time.
     # aarch64-darwin is not supported in older config.sub's
     find libraries -name config.sub -exec cp config.sub {} \;
 
-    runInNixShell ".gitlab/ci.sh setup"
-
-    # make sure $HOME is prisine
-    echo "Deleting $HOME/.cabal"
-    rm -fR $HOME/.cabal
-    runInNixShell "cabal update --index=$HACKAGE_INDEX_STATE"
-    runInNixShell ".gitlab/ci.sh configure"
-    runInNixShell ".gitlab/ci.sh build_hadrian"
-    runInNixShell ".gitlab/ci.sh test_hadrian"
-
-    # Important to run this in nix-shell because $HOME is different there
-    runInNixShell ".gitlab/ci.sh save_cache"
+    .gitlab/ci.sh setup
+    .gitlab/ci.sh configure
+    .gitlab/ci.sh build_hadrian
+    .gitlab/ci.sh test_hadrian
+    .gitlab/ci.sh save_cache
 
   artifacts:
     when: always
diff --git a/.gitlab/ci.sh b/.gitlab/ci.sh
index 85fd59cd59..18e63b33bd 100755
--- a/.gitlab/ci.sh
+++ b/.gitlab/ci.sh
@@ -180,17 +180,14 @@ function show_tool() {
 function set_toolchain_paths() {
   needs_toolchain="1"
   case "$(uname -m)-$(uname)" in
+    # Linux toolchains are included in the Docker image
     *-Linux) needs_toolchain="" ;;
+    # Darwin toolchains are provided via .gitlab/darwin/toolchain.nix
+    *-Darwin) needs_toolchain="" ;;
     *) ;;
   esac
 
-  if [[ -n "${IN_NIX_SHELL:-}" ]]; then
-      needs_toolchain=""
-      GHC="$(which ghc)"
-      CABAL="$(which cabal)"
-      HAPPY="$(which happy)"
-      ALEX="$(which alex)"
-  elif [[ -n "$needs_toolchain" ]]; then
+  if [[ -n "$needs_toolchain" ]]; then
       # These are populated by setup_toolchain
       GHC="$toolchain/bin/ghc$exe"
       CABAL="$toolchain/bin/cabal$exe"
diff --git a/.gitlab/darwin/nix/sources.json b/.gitlab/darwin/nix/sources.json
new file mode 100644
index 0000000000..a6ff5dc415
--- /dev/null
+++ b/.gitlab/darwin/nix/sources.json
@@ -0,0 +1,26 @@
+{
+    "niv": {
+        "branch": "master",
+        "description": "Easy dependency management for Nix projects",
+        "homepage": "https://github.com/nmattia/niv",
+        "owner": "nmattia",
+        "repo": "niv",
+        "rev": "e0ca65c81a2d7a4d82a189f1e23a48d59ad42070",
+        "sha256": "1pq9nh1d8nn3xvbdny8fafzw87mj7gsmp6pxkdl65w2g18rmcmzx",
+        "type": "tarball",
+        "url": "https://github.com/nmattia/niv/archive/e0ca65c81a2d7a4d82a189f1e23a48d59ad42070.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    },
+    "nixpkgs": {
+        "branch": "wip/ghc-8.10.7-darwin",
+        "description": "Nix Packages collection",
+        "homepage": "",
+        "owner": "bgamari",
+        "repo": "nixpkgs",
+        "rev": "37c60356e3f83c708a78a96fdd914b5ffc1f551c",
+        "sha256": "0i5j7nwk4ky0fg4agla3aznadpxz0jyrdwp2q92hyxidra987syn",
+        "type": "tarball",
+        "url": "https://github.com/bgamari/nixpkgs/archive/37c60356e3f83c708a78a96fdd914b5ffc1f551c.tar.gz",
+        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
+    }
+}
diff --git a/.gitlab/darwin/nix/sources.nix b/.gitlab/darwin/nix/sources.nix
new file mode 100644
index 0000000000..1938409ddd
--- /dev/null
+++ b/.gitlab/darwin/nix/sources.nix
@@ -0,0 +1,174 @@
+# This file has been generated by Niv.
+
+let
+
+  #
+  # The fetchers. fetch_<type> fetches specs of type <type>.
+  #
+
+  fetch_file = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchurl { inherit (spec) url sha256; name = name'; }
+      else
+        pkgs.fetchurl { inherit (spec) url sha256; name = name'; };
+
+  fetch_tarball = pkgs: name: spec:
+    let
+      name' = sanitizeName name + "-src";
+    in
+      if spec.builtin or true then
+        builtins_fetchTarball { name = name'; inherit (spec) url sha256; }
+      else
+        pkgs.fetchzip { name = name'; inherit (spec) url sha256; };
+
+  fetch_git = name: spec:
+    let
+      ref =
+        if spec ? ref then spec.ref else
+          if spec ? branch then "refs/heads/${spec.branch}" else
+            if spec ? tag then "refs/tags/${spec.tag}" else
+              abort "In git source '${name}': Please specify `ref`, `tag` or `branch`!";
+    in
+      builtins.fetchGit { url = spec.repo; inherit (spec) rev; inherit ref; };
+
+  fetch_local = spec: spec.path;
+
+  fetch_builtin-tarball = name: throw
+    ''[${name}] The niv type "builtin-tarball" is deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=tarball -a builtin=true'';
+
+  fetch_builtin-url = name: throw
+    ''[${name}] The niv type "builtin-url" will soon be deprecated. You should instead use `builtin = true`.
+        $ niv modify ${name} -a type=file -a builtin=true'';
+
+  #
+  # Various helpers
+  #
+
+  # https://github.com/NixOS/nixpkgs/pull/83241/files#diff-c6f540a4f3bfa4b0e8b6bafd4cd54e8bR695
+  sanitizeName = name:
+    (
+      concatMapStrings (s: if builtins.isList s then "-" else s)
+        (
+          builtins.split "[^[:alnum:]+._?=-]+"
+            ((x: builtins.elemAt (builtins.match "\\.*(.*)" x) 0) name)
+        )
+    );
+
+  # The set of packages used when specs are fetched using non-builtins.
+  mkPkgs = sources: system:
+    let
+      sourcesNixpkgs =
+        import (builtins_fetchTarball { inherit (sources.nixpkgs) url sha256; }) { inherit system; };
+      hasNixpkgsPath = builtins.any (x: x.prefix == "nixpkgs") builtins.nixPath;
+      hasThisAsNixpkgsPath = <nixpkgs> == ./.;
+    in
+      if builtins.hasAttr "nixpkgs" sources
+      then sourcesNixpkgs
+      else if hasNixpkgsPath && ! hasThisAsNixpkgsPath then
+        import <nixpkgs> {}
+      else
+        abort
+          ''
+            Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
+            add a package called "nixpkgs" to your sources.json.
+          '';
+
+  # The actual fetching function.
+  fetch = pkgs: name: spec:
+
+    if ! builtins.hasAttr "type" spec then
+      abort "ERROR: niv spec ${name} does not have a 'type' attribute"
+    else if spec.type == "file" then fetch_file pkgs name spec
+    else if spec.type == "tarball" then fetch_tarball pkgs name spec
+    else if spec.type == "git" then fetch_git name spec
+    else if spec.type == "local" then fetch_local spec
+    else if spec.type == "builtin-tarball" then fetch_builtin-tarball name
+    else if spec.type == "builtin-url" then fetch_builtin-url name
+    else
+      abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";
+
+  # If the environment variable NIV_OVERRIDE_${name} is set, then use
+  # the path directly as opposed to the fetched source.
+  replace = name: drv:
+    let
+      saneName = stringAsChars (c: if isNull (builtins.match "[a-zA-Z0-9]" c) then "_" else c) name;
+      ersatz = builtins.getEnv "NIV_OVERRIDE_${saneName}";
+    in
+      if ersatz == "" then drv else
+        # this turns the string into an actual Nix path (for both absolute and
+        # relative paths)
+        if builtins.substring 0 1 ersatz == "/" then /. + ersatz else /. + builtins.getEnv "PWD" + "/${ersatz}";
+
+  # Ports of functions for older nix versions
+
+  # a Nix version of mapAttrs if the built-in doesn't exist
+  mapAttrs = builtins.mapAttrs or (
+    f: set: with builtins;
+    listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set))
+  );
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/lists.nix#L295
+  range = first: last: if first > last then [] else builtins.genList (n: first + n) (last - first + 1);
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L257
+  stringToCharacters = s: map (p: builtins.substring p 1 s) (range 0 (builtins.stringLength s - 1));
+
+  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L269
+  stringAsChars = f: s: concatStrings (map f (stringToCharacters s));
+  concatMapStrings = f: list: concatStrings (map f list);
+  concatStrings = builtins.concatStringsSep "";
+
+  # https://github.com/NixOS/nixpkgs/blob/8a9f58a375c401b96da862d969f66429def1d118/lib/attrsets.nix#L331
+  optionalAttrs = cond: as: if cond then as else {};
+
+  # fetchTarball version that is compatible between all the versions of Nix
+  builtins_fetchTarball = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchTarball;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchTarball ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      else
+        fetchTarball attrs;
+
+  # fetchurl version that is compatible between all the versions of Nix
+  builtins_fetchurl = { url, name ? null, sha256 }@attrs:
+    let
+      inherit (builtins) lessThan nixVersion fetchurl;
+    in
+      if lessThan nixVersion "1.12" then
+        fetchurl ({ inherit url; } // (optionalAttrs (!isNull name) { inherit name; }))
+      else
+        fetchurl attrs;
+
+  # Create the final "sources" from the config
+  mkSources = config:
+    mapAttrs (
+      name: spec:
+        if builtins.hasAttr "outPath" spec
+        then abort
+          "The values in sources.json should not have an 'outPath' attribute"
+        else
+          spec // { outPath = replace name (fetch config.pkgs name spec); }
+    ) config.sources;
+
+  # The "config" used by the fetchers
+  mkConfig =
+    { sourcesFile ? if builtins.pathExists ./sources.json then ./sources.json else null
+    , sources ? if isNull sourcesFile then {} else builtins.fromJSON (builtins.readFile sourcesFile)
+    , system ? builtins.currentSystem
+    , pkgs ? mkPkgs sources system
+    }: rec {
+      # The sources, i.e. the attribute set of spec name to spec
+      inherit sources;
+
+      # The "pkgs" (evaluated nixpkgs) to use for e.g. non-builtin fetchers
+      inherit pkgs;
+    };
+
+in
+mkSources (mkConfig {}) // { __functor = _: settings: mkSources (mkConfig settings); }
diff --git a/.gitlab/darwin/toolchain.nix b/.gitlab/darwin/toolchain.nix
new file mode 100644
index 0000000000..1042b76c18
--- /dev/null
+++ b/.gitlab/darwin/toolchain.nix
@@ -0,0 +1,102 @@
+{ system }:
+
+let
+  sources = import ./nix/sources.nix;
+  nixpkgsSrc = sources.nixpkgs;
+  pkgs = import nixpkgsSrc { inherit system; };
+in
+
+let
+  hsPkgs = pkgs.haskellPackages;
+  alex = hsPkgs.alex;
+  happy = hsPkgs.happy;
+  targetTriple = pkgs.stdenv.targetPlatform.config;
+
+  ghc = pkgs.stdenv.mkDerivation rec {
+    version = "8.10.7";
+    name = "ghc";
+    src =
+      let
+        bindists = {
+          aarch64-darwin = {
+            url = "https://downloads.haskell.org/ghc/${version}/ghc-${version}-aarch64-apple-darwin.tar.xz";
+            sha256 = "sha256:075skdnsa072088a8jfkqac7pphkgzlgqpspb8xa7ljzqg1ryinw";
+          };
+          x86_64-darwin = {
+            url = "https://downloads.haskell.org/ghc/${version}/ghc-${version}-x86_64-apple-darwin.tar.xz";
+            sha256 = "sha256:0ir02gjyb4l073z4gs3f1zjkx04n14dp7a5z4cqzbj9qqgwv0z98";
+          };
+        };
+      in pkgs.fetchurl bindists.${pkgs.stdenv.hostPlatform.system};
+    configureFlags = [
+      "CC=/usr/bin/clang"
+      "CLANG=/usr/bin/clang"
+      "LLC=${llvm}/bin/llc"
+      "OPT=${llvm}/bin/opt"
+      "CONF_CC_OPTS_STAGE2=--target=${targetTriple}"
+      "CONF_CXX_OPTS_STAGE2=--target=${targetTriple}"
+      "CONF_GCC_LINKER_OPTS_STAGE2=--target=${targetTriple}"
+    ];
+    buildPhase = "true";
+
+    # N.B. Work around #20253.
+    nativeBuildInputs = [ pkgs.gnused ];
+    postInstallPhase = ''
+      settings="$out/lib/ghc-${version}/settings"
+      sed -i -e "s%\"llc\"%\"${llvm}/bin/llc\"%" $settings
+      sed -i -e "s%\"opt\"%\"${llvm}/bin/opt\"%" $settings
+      sed -i -e "s%\"clang\"%\"/usr/bin/clang\"%" $settings
+      sed -i -e 's%("C compiler command", "")%("C compiler command", "/usr/bin/clang")%' $settings
+      sed -i -e 's%("C compiler flags", "")%("C compiler flags", "--target=${targetTriple}")%' $settings
+      sed -i -e 's%("C++ compiler flags", "")%("C++ compiler flags", "--target=${targetTriple}")%' $settings
+      sed -i -e 's%("C compiler link flags", "")%("C compiler link flags", "--target=${targetTriple}")%' $settings
+    '';
+
+    # Sanity check: verify that we can compile hello world.
+    doInstallCheck = true;
+    installCheckPhase = ''
+      unset DYLD_LIBRARY_PATH
+      $out/bin/ghc --info
+      cd $TMP
+      mkdir test-ghc; cd test-ghc
+      cat > main.hs << EOF
+        {-# LANGUAGE TemplateHaskell #-}
+        module Main where
+        main = putStrLn \$([|"yes"|])
+      EOF
+      $out/bin/ghc --make -v3 main.hs || exit 1
+      echo compilation ok
+      [ $(./main) == "yes" ]
+    '';
+  };
+
+  ourtexlive = with pkgs;
+    texlive.combine {
+      inherit (texlive)
+        scheme-medium collection-xetex fncychap titlesec tabulary varwidth
+        framed capt-of wrapfig needspace dejavu-otf helvetic upquote;
+    };
+  fonts = with pkgs; makeFontsConf { fontDirectories = [ dejavu_fonts ]; };
+
+  llvm = pkgs.llvm_11;
+in
+pkgs.writeTextFile {
+  name = "toolchain";
+  text = ''
+    export PATH
+    PATH="${pkgs.autoconf}/bin:$PATH"
+    PATH="${pkgs.automake}/bin:$PATH"
+    PATH="${pkgs.coreutils}/bin:$PATH"
+    export FONTCONFIG_FILE=${fonts}
+    export XELATEX="${ourtexlive}/bin/xelatex"
+    export MAKEINDEX="${ourtexlive}/bin/makeindex"
+    export HAPPY="${happy}/bin/happy"
+    export ALEX="${alex}/bin/alex"
+    export GHC="${ghc}/bin/ghc"
+    export LLC="${llvm}/bin/llc"
+    export OPT="${llvm}/bin/opt"
+    export SPHINXBUILD="${pkgs.python3Packages.sphinx}/bin/sphinx-build"
+    export CABAL_INSTALL="${pkgs.cabal-install}/bin/cabal"
+    export CABAL="$CABAL_INSTALL"
+  '';
+}
diff --git a/.gitlab/shell.nix b/.gitlab/shell.nix
deleted file mode 100644
index 1ded62d982..0000000000
--- a/.gitlab/shell.nix
+++ /dev/null
@@ -1,92 +0,0 @@
-{ system ? "aarch64-darwin"
-#, nixpkgs ? fetchTarball https://github.com/angerman/nixpkgs/archive/257cb120334.tar.gz #apple-silicon.tar.gz
-, pkgs ? import <nixpkgs> { inherit system; }
-, compiler ? if system == "aarch64-darwin" then "ghc8103Binary" else "ghc8103"
-}: pkgs.mkShell {
-  # this prevents nix from trying to write the env-vars file.
-  # we can't really, as NIX_BUILD_TOP/env-vars is not set.
-  noDumpEnvVars=1;
-
-  # stop polluting LDFLAGS with -liconv
-  dontAddExtraLibs = true;
-
-  # we need to inject ncurses into --with-curses-libraries.
-  # the real fix is to teach terminfo to use libcurses on macOS.
-  # CONFIGURE_ARGS = "--with-intree-gmp --with-curses-libraries=${pkgs.ncurses.out}/lib";
-  CONFIGURE_ARGS = "--with-intree-gmp";
-
-  # magic speedup pony :facepalm:
-  #
-  # nix has the ugly habbit of duplicating ld flags more than necessary.  This
-  # somewhat consolidates this.
-  shellHook = ''
-  echo $NIX_LDFLAGS
-  export NIX_LDFLAGS=$(for a in $NIX_LDFLAGS; do echo $a; done |sort|uniq|xargs)
-  export NIX_LDFLAGS_FOR_TARGET=$(for a in $NIX_LDFLAGS_FOR_TARGET; do echo $a; done |sort|uniq|xargs)
-  export NIX_LDFLAGS_FOR_TARGET=$(comm -3 <(for l in $NIX_LDFLAGS_FOR_TARGET; do echo $l; done) <(for l in $NIX_LDFLAGS; do echo $l; done))
-
-
-  # Impurity hack for GHC releases.
-  #################################
-  # We don't want binary releases to depend on nix, thus we'll need to make sure we don't leak in references.
-  # GHC externally depends only on iconv and curses.  However we can't force a specific curses library for
-  # the terminfo package, as such we'll need to make sure we only look in the system path for the curses library
-  # and not pick up the tinfo from the nix provided ncurses package.
-  #
-  # We also need to force us to use the systems COREFOUNDATION, not the one that nix builds. Again this is impure,
-  # but it will allow us to have proper binary distributions.
-  #
-  # do not use nixpkgs provided core foundation
-  export NIX_COREFOUNDATION_RPATH=/System/Library/Frameworks
-  # drop curses from the LDFLAGS, we really want the system ones, not the nix ones.
-  export NIX_LDFLAGS=$(for lib in $NIX_LDFLAGS; do case "$lib" in *curses*);; *) echo -n "$lib ";; esac; done;)
-  export NIX_CFLAGS_COMPILE+=" -Wno-nullability-completeness -Wno-availability -Wno-expansion-to-defined -Wno-builtin-requires-header -Wno-unused-command-line-argument"
-
-  # unconditionally add the MacOSX.sdk and TargetConditional.h
-  export NIX_CFLAGS_COMPILE+=" -isystem /Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include"
-  export NIX_LDFLAGS="-L/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib $NIX_LDFLAGS"
-
-  export MACOSX_DEPLOYMENT_TARGET=10.7
-
-  '';
-
-  nativeBuildInputs = (with pkgs; [
-    # This needs to come *before* ghc,
-    # otherwise we migth end up with the clang from
-    # the bootstrap GHC in PATH with higher priority.
-    clang_11
-    llvm_11
-
-    haskell.compiler.${compiler}
-    haskell.packages.${compiler}.cabal-install
-    haskell.packages.${compiler}.alex
-    haskell.packages.${compiler}.happy # _1_19_12 is needed for older GHCs.
-
-    automake
-    autoconf
-    m4
-
-    gmp
-    zlib.out
-    zlib.dev
-    glibcLocales
-    # locale doesn't build yet :-/
-    # locale
-
-    git
-
-    python3
-    # python3Full
-    # python3Packages.sphinx
-    perl
-
-    which
-    wget
-    file
-
-    xz
-    xlibs.lndir
-
-    cacert ])
-  ++ (with pkgs.darwin.apple_sdk.frameworks; [ Foundation Security ]);
-}