Merge pull request #26799 from obsidiansystems/cross-haskell

haskell infra: Fix cross compilation to work with new system

pkgs/development/compilers/ghc/6.10.2-binary.nix

···
     [ $(./main) == "yes" ]
   '';
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPrefix = "";
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta = {
     homepage = http://haskell.org/ghc;

pkgs/development/compilers/ghc/6.10.4.nix

···
 
   NIX_CFLAGS_COMPILE = "-fomit-frame-pointer";
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPrefix = "";
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta = {
     homepage = http://haskell.org/ghc;

pkgs/development/compilers/ghc/6.12.3.nix

···
   '';
 
   preConfigure = ''
-    echo "${buildMK}" > mk/build.mk
+    echo -n "${buildMK}" > mk/build.mk
   '';
 
   configureFlags = [
···
   # that in turn causes GHCi to abort
   stripDebugFlags=["-S" "--keep-file-symbols"];
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPrefix = "";
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta = {
     homepage = http://haskell.org/ghc;

pkgs/development/compilers/ghc/7.0.4-binary.nix

···
     [ $(./main) == "yes" ]
   '';
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPrefix = "";
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta.license = stdenv.lib.licenses.bsd3;
   meta.platforms = ["x86_64-linux" "i686-linux" "x86_64-darwin"];

pkgs/development/compilers/ghc/7.0.4.nix

···
   '';
 
   preConfigure = ''
-    echo "${buildMK}" > mk/build.mk
+    echo -n "${buildMK}" > mk/build.mk
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     find . -name '*.hs'  | xargs sed -i -e 's|ASSERT (|ASSERT(|' -e 's|ASSERT2 (|ASSERT2(|' -e 's|WARN (|WARN(|'
···
   # that in turn causes GHCi to abort
   stripDebugFlags=["-S" "--keep-file-symbols"];
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPrefix = "";
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta = {
     homepage = http://haskell.org/ghc;

pkgs/development/compilers/ghc/7.10.3.nix

···
 , buildPlatform, hostPlatform, targetPlatform
 
 # build-tools
-, bootPkgs, hscolour, llvm_35
+, bootPkgs, hscolour
 , coreutils, fetchurl, fetchpatch, perl
 , docbook_xsl, docbook_xml_dtd_45, docbook_xml_dtd_42, libxml2, libxslt
 
-, libiconv ? null, ncurses
+, libffi, libiconv ? null, ncurses
+
+, useLLVM ? !targetPlatform.isx86
+, # LLVM is conceptually a run-time-only depedendency, but for
+  # non-x86, we need LLVM to bootstrap later stages, so it becomes a
+  # build-time dependency too.
+  buildLlvmPackages, 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 ? false, gmp ? null
+
+, # If enabled, use -fPIC when compiling static libs.
+  enableRelocatedStaticLibs ? targetPlatform != hostPlatform
+
+, # Whether to build dynamic libs for the standard library (on the target
+  # platform). Static libs are always built.
+  enableShared ? true
 }:
 
 assert !enableIntegerSimple -> gmp != null;
···
     sha256 = "1j45z4kcd3w1rzm4hapap2xc16bbh942qnzzdbdjcwqznsccznf0";
   };
 
+  buildMK = ''
+    DYNAMIC_GHC_PROGRAMS = ${if enableShared then "YES" else "NO"}
+  '' + stdenv.lib.optionalString enableIntegerSimple ''
+    INTEGER_LIBRARY = integer-simple
+  '' + stdenv.lib.optionalString (targetPlatform != hostPlatform) ''
+    BuildFlavour = perf-cross
+    Stage1Only = YES
+    HADDOCK_DOCS = NO
+  '' + stdenv.lib.optionalString enableRelocatedStaticLibs ''
+    GhcLibHcOpts += -fPIC
+    GhcRtsHcOpts += -fPIC
+  '';
+
+  # Splicer will pull out correct variations
+  libDeps = platform: [ ncurses ]
+    ++ stdenv.lib.optional (!enableIntegerSimple) gmp
+    ++ stdenv.lib.optional (platform.libc != "glibc") libiconv;
+
+  toolsForTarget =
+    if hostPlatform == buildPlatform then
+      [ targetPackages.stdenv.cc ] ++ stdenv.lib.optional useLLVM llvmPackages.llvm
+    else assert targetPlatform == hostPlatform; # build != host == target
+      [ stdenv.cc ] ++ stdenv.lib.optional useLLVM buildLlvmPackages.llvm;
+
+  targetCC = builtins.head toolsForTarget;
+
 in
 
 stdenv.mkDerivation rec {
···
     sha256 = "1vsgmic8csczl62ciz51iv8nhrkm72lyhbz7p7id13y2w7fcx46g";
   };
 
+  enableParallelBuilding = true;
+
+  outputs = [ "out" "doc" ];
+
   patches = [
     docFixes
     ./relocation.patch
   ];
 
-  buildInputs = [ ghc perl libxml2 libxslt docbook_xsl docbook_xml_dtd_45 docbook_xml_dtd_42 hscolour ] ++ stdenv.lib.optionals targetPlatform.isArm [ llvm_35 ];
-
-  enableParallelBuilding = true;
-
-  outputs = [ "out" "doc" ];
-
+  # GHC is a bit confused on its cross terminology.
   preConfigure = ''
+    for env in $(env | grep '^TARGET_' | sed -E 's|\+?=.*||'); do
+      export "''${env#TARGET_}=''${!env}"
+    done
+    # GHC is a bit confused on its cross terminology, as these would normally be
+    # the *host* tools.
+    export CC="${targetCC}/bin/${targetCC.targetPrefix}cc"
+    export CXX="${targetCC}/bin/${targetCC.targetPrefix}cxx"
+    export LD="${targetCC.bintools}/bin/${targetCC.bintools.targetPrefix}ld"
+    export AS="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}as"
+    export AR="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ar"
+    export NM="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}nm"
+    export RANLIB="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ranlib"
+    export READELF="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}readelf"
+    export STRIP="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}strip"
+    echo -n "${buildMK}" > mk/build.mk
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
   '' + stdenv.lib.optionalString (!stdenv.isDarwin) ''
-    export NIX_LDFLAGS="$NIX_LDFLAGS -rpath $out/lib/ghc-${version}"
+    export NIX_LDFLAGS+=" -rpath $out/lib/ghc-${version}"
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     export NIX_LDFLAGS+=" -no_dtrace_dof"
-  '' + stdenv.lib.optionalString enableIntegerSimple ''
-    echo "INTEGER_LIBRARY=integer-simple" > mk/build.mk
   '';
 
+  # TODO(@Ericson2314): Always pass "--target" and always prefix.
+  configurePlatforms = [ "build" "host" ]
+    ++ stdenv.lib.optional (targetPlatform != hostPlatform) "target";
+  # `--with` flags for libraries needed for RTS linker
   configureFlags = [
-    "--with-gcc=${stdenv.cc}/bin/cc"
-    "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
     "--datadir=$doc/share/doc/ghc"
-  ] ++ stdenv.lib.optional (! enableIntegerSimple) [
+    "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && ! enableIntegerSimple) [
     "--with-gmp-includes=${gmp.dev}/include" "--with-gmp-libraries=${gmp.out}/lib"
-  ] ++ stdenv.lib.optional stdenv.isDarwin [
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && hostPlatform.libc != "glibc") [
     "--with-iconv-includes=${libiconv}/include" "--with-iconv-libraries=${libiconv}/lib"
+  ] ++ stdenv.lib.optionals (targetPlatform != hostPlatform) [
+    "--enable-bootstrap-with-devel-snapshot"
+  ] ++ stdenv.lib.optionals (targetPlatform.isDarwin && targetPlatform.isAarch64) [
+    # fix for iOS: https://www.reddit.com/r/haskell/comments/4ttdz1/building_an_osxi386_to_iosarm64_cross_compiler/d5qvd67/
+    "--disable-large-address-space"
   ];
 
+  # Hack to make sure we never to the relaxation `$PATH` and hooks support for
+  # compatability. This will be replaced with something clearer in a future
+  # masss-rebuild.
+  crossConfig = true;
+
+  nativeBuildInputs = [
+    ghc perl libxml2 libxslt docbook_xsl docbook_xml_dtd_45 docbook_xml_dtd_42 hscolour
+  ];
+
+  # For building runtime libs
+  depsBuildTarget = toolsForTarget;
+
+  buildInputs = libDeps hostPlatform;
+
+  propagatedBuildInputs = [ targetPackages.stdenv.cc ]
+    ++ stdenv.lib.optional useLLVM llvmPackages.llvm;
+
+  depsTargetTarget = map stdenv.lib.getDev (libDeps targetPlatform);
+  depsTargetTargetPropagated = map (stdenv.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" ] ++ stdenv.lib.optional (!targetPlatform.isDarwin) "--keep-file-symbols";
···
 
   passthru = {
     inherit bootPkgs targetPrefix;
+
+    inherit llvmPackages;
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
   };
 
   meta = {
···
     maintainers = with stdenv.lib.maintainers; [ marcweber andres peti ];
     inherit (ghc.meta) license platforms;
   };
+
 }

pkgs/development/compilers/ghc/7.2.2.nix

···
       libraries/base_CONFIGURE_OPTS += --configure-option=--with-iconv-libraries="${libiconv}/lib"
     ''}
   '' + (if enableIntegerSimple then ''
-    INTEGER_LIBRARY=integer-simple
+    INTEGER_LIBRARY = integer-simple
   '' else ''
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-libraries="${gmp.out}/lib"
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-includes="${gmp.dev}/include"
   '');
 
   preConfigure = ''
-    echo "${buildMK}" > mk/build.mk
+    echo -n "${buildMK}" > mk/build.mk
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     find . -name '*.hs'  | xargs sed -i -e 's|ASSERT (|ASSERT(|' -e 's|ASSERT2 (|ASSERT2(|' -e 's|WARN (|WARN(|'
···
   # that in turn causes GHCi to abort
   stripDebugFlags=["-S" "--keep-file-symbols"];
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPprefix = "";
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta = {
     homepage = http://haskell.org/ghc;

pkgs/development/compilers/ghc/7.4.2-binary.nix

···
     [ $(./main) == "yes" ]
   '';
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPrefix = "";
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta.license = stdenv.lib.licenses.bsd3;
   meta.platforms = ["x86_64-linux" "i686-linux" "x86_64-darwin"];

pkgs/development/compilers/ghc/7.4.2.nix

···
       libraries/base_CONFIGURE_OPTS += --configure-option=--with-iconv-libraries="${libiconv}/lib"
     ''}
   '' + (if enableIntegerSimple then ''
-    INTEGER_LIBRARY=integer-simple
+    INTEGER_LIBRARY = integer-simple
   '' else ''
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-libraries="${gmp.out}/lib"
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-includes="${gmp.dev}/include"
   '');
 
   preConfigure = ''
-    echo "${buildMK}" > mk/build.mk
+    echo -n "${buildMK}" > mk/build.mk
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
   '' + stdenv.lib.optionalString (!stdenv.isDarwin) ''
-    export NIX_LDFLAGS="$NIX_LDFLAGS -rpath $out/lib/ghc-${version}"
+    export NIX_LDFLAGS+=" -rpath $out/lib/ghc-${version}"
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     find . -name '*.hs'  | xargs sed -i -e 's|ASSERT (|ASSERT(|' -e 's|ASSERT2 (|ASSERT2(|' -e 's|WARN (|WARN(|'
     find . -name '*.lhs' | xargs sed -i -e 's|ASSERT (|ASSERT(|' -e 's|ASSERT2 (|ASSERT2(|' -e 's|WARN (|WARN(|'
···
   # that in turn causes GHCi to abort
   stripDebugFlags = [ "-S" ] ++ stdenv.lib.optional (!stdenv.isDarwin) "--keep-file-symbols";
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPrefix = "";
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta = {
     homepage = http://haskell.org/ghc;

pkgs/development/compilers/ghc/7.6.3.nix

···
     SRC_HC_OPTS += ${ghcFlags}
     SRC_CC_OPTS += ${cFlags}
   '' + (if enableIntegerSimple then ''
-    INTEGER_LIBRARY=integer-simple
+    INTEGER_LIBRARY = integer-simple
   '' else ''
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-libraries="${gmp.out}/lib"
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-includes="${gmp.dev}/include"
   '');
 
   preConfigure = ''
-    echo "${buildMK}" > mk/build.mk
+    echo -n "${buildMK}" > mk/build.mk
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
 
   '' + stdenv.lib.optionalString stdenv.isLinux ''
···
     sed -i -e 's|"\$topdir"|"\$topdir" ${ghcFlags}|' ghc/ghc.wrapper
 
   '' + stdenv.lib.optionalString (!stdenv.isDarwin) ''
-    export NIX_LDFLAGS="$NIX_LDFLAGS -rpath $out/lib/ghc-${version}"
+    export NIX_LDFLAGS+=" -rpath $out/lib/ghc-${version}"
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     find . -name '*.hs'  | xargs sed -i -e 's|ASSERT (|ASSERT(|' -e 's|ASSERT2 (|ASSERT2(|' -e 's|WARN (|WARN(|'
     find . -name '*.lhs' | xargs sed -i -e 's|ASSERT (|ASSERT(|' -e 's|ASSERT2 (|ASSERT2(|' -e 's|WARN (|WARN(|'
···
   # that in turn causes GHCi to abort
   stripDebugFlags = [ "-S" ] ++ stdenv.lib.optional (!stdenv.isDarwin) "--keep-file-symbols";
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPrefix = "";
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta = {
     homepage = http://haskell.org/ghc;

pkgs/development/compilers/ghc/7.8.4.nix

···
-{ stdenv, fetchurl, ghc, perl, ncurses, libiconv
+{ stdenv, targetPackages
+
+, fetchurl, ghc, perl
+, libffi, libiconv ? null, ncurses
 
 , # If enabled, GHC will be built with the GPL-free but slower integer-simple
   # library instead of the faster but GPLed integer-gmp library.
···
 assert stdenv.targetPlatform == stdenv.hostPlatform;
 assert !enableIntegerSimple -> gmp != null;
 
-stdenv.mkDerivation (rec {
-  version = "7.8.4";
-  name = "ghc-${version}";
-
-  src = fetchurl {
-    url = "https://downloads.haskell.org/~ghc/${version}/ghc-${version}-src.tar.xz";
-    sha256 = "1i4254akbb4ym437rf469gc0m40bxm31blp6s1z1g15jmnacs6f3";
-  };
-
-  patches = [ ./relocation.patch ];
-
-  buildInputs = [ ghc perl ncurses ]
-                ++ stdenv.lib.optional (!enableIntegerSimple) gmp;
-
-  enableParallelBuilding = true;
-
+let
   buildMK = ''
     libraries/terminfo_CONFIGURE_OPTS += --configure-option=--with-curses-includes="${ncurses.dev}/include"
     libraries/terminfo_CONFIGURE_OPTS += --configure-option=--with-curses-libraries="${ncurses.out}/lib"
     DYNAMIC_BY_DEFAULT = NO
-    ${stdenv.lib.optionalString stdenv.isDarwin ''
+    ${stdenv.lib.optionalString (stdenv.hostPlatform.libc != "glibc") ''
       libraries/base_CONFIGURE_OPTS += --configure-option=--with-iconv-includes="${libiconv}/include"
       libraries/base_CONFIGURE_OPTS += --configure-option=--with-iconv-libraries="${libiconv}/lib"
     ''}
   '' + (if enableIntegerSimple then ''
-    INTEGER_LIBRARY=integer-simple
+    INTEGER_LIBRARY = integer-simple
   '' else ''
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-libraries="${gmp.out}/lib"
     libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-includes="${gmp.dev}/include"
   '');
 
+  # Splicer will pull out correct variations
+  libDeps = [ ncurses ]
+    ++ stdenv.lib.optional (!enableIntegerSimple) gmp
+    ++ stdenv.lib.optional (stdenv.hostPlatform.libc != "glibc") libiconv;
+
+in
+
+stdenv.mkDerivation rec {
+  version = "7.8.4";
+  name = "ghc-${version}";
+
+  src = fetchurl {
+    url = "http://www.haskell.org/ghc/dist/${version}/${name}-src.tar.xz";
+    sha256 = "1i4254akbb4ym437rf469gc0m40bxm31blp6s1z1g15jmnacs6f3";
+  };
+
+  enableParallelBuilding = true;
+
+  patches = [ ./relocation.patch ]
+    ++ stdenv.lib.optional stdenv.isDarwin ./hpc-7.8.4.patch;
+
   preConfigure = ''
-    echo "${buildMK}" > mk/build.mk
+    echo -n "${buildMK}" > mk/build.mk
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
   '' + stdenv.lib.optionalString (!stdenv.isDarwin) ''
-    export NIX_LDFLAGS="$NIX_LDFLAGS -rpath $out/lib/ghc-${version}"
+    export NIX_LDFLAGS+=" -rpath $out/lib/ghc-${version}"
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     export NIX_LDFLAGS+=" -no_dtrace_dof"
   '';
 
+  # TODO(@Ericson2314): Always pass "--target" and always prefix.
+  configurePlatforms = [ "build" "host" ];
+
+  nativeBuildInputs = [ ghc perl ];
+  depsBuildTarget = [ targetPackages.stdenv.cc ];
+
+  buildInputs = libDeps;
+  propagatedBuildInputs = [ targetPackages.stdenv.cc ];
+
+  depsTargetTarget = map stdenv.lib.getDev libDeps;
+  depsTargetTargetPropagated = map (stdenv.lib.getOutput "out") libDeps;
+
   # required, because otherwise all symbols from HSffi.o are stripped, and
   # that in turn causes GHCi to abort
   stripDebugFlags = [ "-S" ] ++ stdenv.lib.optional (!stdenv.isDarwin) "--keep-file-symbols";
 
-  passthru = { targetPrefix = ""; };
+  passthru = {
+    targetPrefix = "";
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
+  };
 
   meta = {
     homepage = http://haskell.org/ghc;
···
     inherit (ghc.meta) license platforms;
   };
 
-} // stdenv.lib.optionalAttrs stdenv.isDarwin {
-  # https://ghc.haskell.org/trac/ghc/ticket/9762
-  patches = [ ./hpc-7.8.4.patch ];
-})
+}

pkgs/development/compilers/ghc/8.0.2.nix

···
 , buildPlatform, hostPlatform, targetPlatform
 
 # build-tools
-, bootPkgs, hscolour, llvm_37
-, coreutils, fetchurl, fetchpatch, patchutils, perl, sphinx
+, bootPkgs, hscolour
+, coreutils, fetchpatch, fetchurl, perl, sphinx
 
-, libiconv ? null, ncurses
+, libffi, libiconv ? null, ncurses
+
+, useLLVM ? !targetPlatform.isx86
+, # LLVM is conceptually a run-time-only depedendency, but for
+  # non-x86, we need LLVM to bootstrap later stages, so it becomes a
+  # build-time dependency too.
+  buildLlvmPackages, 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 ? false, gmp ? null
+
+, # If enabled, use -fPIC when compiling static libs.
+  enableRelocatedStaticLibs ? targetPlatform != hostPlatform
+
+, # Whether to build dynamic libs for the standard library (on the target
+  # platform). Static libs are always built.
+  enableShared ? true
 }:
 
 assert !enableIntegerSimple -> gmp != null;
···
   targetPrefix = stdenv.lib.optionalString
     (targetPlatform != hostPlatform)
     "${targetPlatform.config}-";
+
+  buildMK = ''
+    DYNAMIC_GHC_PROGRAMS = ${if enableShared then "YES" else "NO"}
+  '' + stdenv.lib.optionalString enableIntegerSimple ''
+    INTEGER_LIBRARY = integer-simple
+  '' + stdenv.lib.optionalString (targetPlatform != hostPlatform) ''
+    BuildFlavour = perf-cross
+    Stage1Only = YES
+    HADDOCK_DOCS = NO
+  '' + stdenv.lib.optionalString enableRelocatedStaticLibs ''
+    GhcLibHcOpts += -fPIC
+    GhcRtsHcOpts += -fPIC
+  '';
+
+  # Splicer will pull out correct variations
+  libDeps = platform: [ ncurses ]
+    ++ stdenv.lib.optional (!enableIntegerSimple) gmp
+    ++ stdenv.lib.optional (platform.libc != "glibc") libiconv;
+
+  toolsForTarget =
+    if hostPlatform == buildPlatform then
+      [ targetPackages.stdenv.cc ] ++ stdenv.lib.optional useLLVM llvmPackages.llvm
+    else assert targetPlatform == hostPlatform; # build != host == target
+      [ stdenv.cc ] ++ stdenv.lib.optional useLLVM buildLlvmPackages.llvm;
+
+  targetCC = builtins.head toolsForTarget;
+
 in
 stdenv.mkDerivation rec {
   version = "8.0.2";
···
     sha256 = "1c8qc4fhkycynk4g1f9hvk53dj6a1vvqi6bklqznns6hw59m8qhi";
   };
 
-  patches = [ ./ghc-gold-linker.patch ]
-    ++ stdenv.lib.optional stdenv.isLinux ./ghc-no-madv-free.patch
-    ++ stdenv.lib.optional stdenv.isDarwin ./ghc-8.0.2-no-cpp-warnings.patch;
-
-  buildInputs = [ ghc perl hscolour sphinx ] ++ stdenv.lib.optionals (stdenv.isArm || stdenv.isAarch64) [ llvm_37 ];
-
   enableParallelBuilding = true;
 
   outputs = [ "out" "man" "doc" ];
 
+  patches = [
+    ./ghc-gold-linker.patch
+    (fetchpatch { # Unreleased 1.24.x commit
+      url = "https://github.com/haskell/cabal/commit/6394cb0b6eba91a8692a3d04b2b56935aed7cccd.patch";
+      sha256 = "14xxjg0nb1j1pw0riac3v385ka92qhxxblfmwyvbghz7kry6axy0";
+      stripLen = 1;
+      extraPrefix = "libraries/Cabal/";
+    })
+  ] ++ stdenv.lib.optional stdenv.isLinux ./ghc-no-madv-free.patch
+    ++ stdenv.lib.optional stdenv.isDarwin ./ghc-8.0.2-no-cpp-warnings.patch;
+
+  # GHC is a bit confused on its cross terminology.
   preConfigure = ''
+    for env in $(env | grep '^TARGET_' | sed -E 's|\+?=.*||'); do
+      export "''${env#TARGET_}=''${!env}"
+    done
+    # GHC is a bit confused on its cross terminology, as these would normally be
+    # the *host* tools.
+    export CC="${targetCC}/bin/${targetCC.targetPrefix}cc"
+    export CXX="${targetCC}/bin/${targetCC.targetPrefix}cxx"
+    export LD="${targetCC.bintools}/bin/${targetCC.bintools.targetPrefix}ld"
+    export AS="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}as"
+    export AR="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ar"
+    export NM="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}nm"
+    export RANLIB="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ranlib"
+    export READELF="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}readelf"
+    export STRIP="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}strip"
+    echo -n "${buildMK}" > mk/build.mk
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
   '' + stdenv.lib.optionalString (!stdenv.isDarwin) ''
-    export NIX_LDFLAGS="$NIX_LDFLAGS -rpath $out/lib/ghc-${version}"
+    export NIX_LDFLAGS+=" -rpath $out/lib/ghc-${version}"
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     export NIX_LDFLAGS+=" -no_dtrace_dof"
-  '' + stdenv.lib.optionalString enableIntegerSimple ''
-    echo "INTEGER_LIBRARY=integer-simple" > mk/build.mk
   '';
 
+  # TODO(@Ericson2314): Always pass "--target" and always prefix.
+  configurePlatforms = [ "build" "host" ]
+    ++ stdenv.lib.optional (targetPlatform != hostPlatform) "target";
+  # `--with` flags for libraries needed for RTS linker
   configureFlags = [
-    "--with-gcc=${stdenv.cc}/bin/cc"
+    "--datadir=$doc/share/doc/ghc"
     "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
-    "--datadir=$doc/share/doc/ghc"
-  ] ++ stdenv.lib.optional (! enableIntegerSimple) [
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && ! enableIntegerSimple) [
     "--with-gmp-includes=${gmp.dev}/include" "--with-gmp-libraries=${gmp.out}/lib"
-  ] ++ stdenv.lib.optional stdenv.isDarwin [
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && hostPlatform.libc != "glibc") [
     "--with-iconv-includes=${libiconv}/include" "--with-iconv-libraries=${libiconv}/lib"
+  ] ++ stdenv.lib.optionals (targetPlatform != hostPlatform) [
+    "--enable-bootstrap-with-devel-snapshot"
   ] ++ stdenv.lib.optionals (targetPlatform.isDarwin && targetPlatform.isAarch64) [
     # fix for iOS: https://www.reddit.com/r/haskell/comments/4ttdz1/building_an_osxi386_to_iosarm64_cross_compiler/d5qvd67/
     "--disable-large-address-space"
   ];
 
+  # Hack to make sure we never to the relaxation `$PATH` and hooks support for
+  # compatability. This will be replaced with something clearer in a future
+  # masss-rebuild.
+  crossConfig = true;
+
+  nativeBuildInputs = [ ghc perl hscolour sphinx ];
+
+  # For building runtime libs
+  depsBuildTarget = toolsForTarget;
+
+  buildInputs = libDeps hostPlatform;
+
+  propagatedBuildInputs = [ targetPackages.stdenv.cc ]
+    ++ stdenv.lib.optional useLLVM llvmPackages.llvm;
+
+  depsTargetTarget = map stdenv.lib.getDev (libDeps targetPlatform);
+  depsTargetTargetPropagated = map (stdenv.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" ] ++ stdenv.lib.optional (!targetPlatform.isDarwin) "--keep-file-symbols";
 
+  # zsh and other shells are smart about `{ghc}` but bash isn't, and doesn't
+  # treat that as a unary `{x,y,z,..}` repetition.
   postInstall = ''
     paxmark m $out/lib/${name}/bin/${if targetPlatform != hostPlatform then "ghc" else "{ghc,haddock}"}
 
···
 
   passthru = {
     inherit bootPkgs targetPrefix;
+
+    inherit llvmPackages;
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
   };
 
   meta = {

pkgs/development/compilers/ghc/8.2.2.nix

···
 { stdenv, targetPackages
 , buildPlatform, hostPlatform, targetPlatform
-, selfPkgs, cross ? null
 
 # build-tools
-, bootPkgs, alex, happy, hscolour, llvm_39
-, autoconf, automake, coreutils, fetchurl, perl, python3, sphinx
+, bootPkgs, alex, happy, hscolour
+, autoconf, autoreconfHook, automake, coreutils, fetchurl, fetchpatch, perl, python3, sphinx
 
-, libiconv ? null, ncurses
+, libffi, libiconv ? null, ncurses
+
+, useLLVM ? !targetPlatform.isx86
+, # LLVM is conceptually a run-time-only depedendency, but for
+  # non-x86, we need LLVM to bootstrap later stages, so it becomes a
+  # build-time dependency too.
+  buildLlvmPackages, 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 ? false, gmp ? null
+
+, # If enabled, use -fPIC when compiling static libs.
+  enableRelocatedStaticLibs ? targetPlatform != hostPlatform
+
+, # Whether to build dynamic libs for the standard library (on the target
+  # platform). Static libs are always built.
+  enableShared ?
+    !(targetPlatform.isDarwin
+      # On iOS, dynamic linking is not supported
+      && (targetPlatform.isAarch64 || targetPlatform.isArm))
 }:
 
 assert !enableIntegerSimple -> gmp != null;
···
   targetPrefix = stdenv.lib.optionalString
     (targetPlatform != hostPlatform)
     "${targetPlatform.config}-";
+
+  buildMK = ''
+    DYNAMIC_GHC_PROGRAMS = ${if enableShared then "YES" else "NO"}
+  '' + stdenv.lib.optionalString enableIntegerSimple ''
+    INTEGER_LIBRARY = integer-simple
+  '' + stdenv.lib.optionalString (targetPlatform != hostPlatform) ''
+    BuildFlavour = perf-cross
+    Stage1Only = YES
+    HADDOCK_DOCS = NO
+    BUILD_SPHINX_HTML = NO
+    BUILD_SPHINX_PDF = NO
+  '' + stdenv.lib.optionalString enableRelocatedStaticLibs ''
+    GhcLibHcOpts += -fPIC
+    GhcRtsHcOpts += -fPIC
+  '';
+
+  # Splicer will pull out correct variations
+  libDeps = platform: [ ncurses ]
+    ++ stdenv.lib.optional (!enableIntegerSimple) gmp
+    ++ stdenv.lib.optional (platform.libc != "glibc") libiconv;
+
+  toolsForTarget =
+    if hostPlatform == buildPlatform then
+      [ targetPackages.stdenv.cc ] ++ stdenv.lib.optional useLLVM llvmPackages.llvm
+    else assert targetPlatform == hostPlatform; # build != host == target
+      [ stdenv.cc ] ++ stdenv.lib.optional useLLVM buildLlvmPackages.llvm;
+
+  targetCC = builtins.head toolsForTarget;
+
 in
-stdenv.mkDerivation (rec {
+stdenv.mkDerivation rec {
   version = "8.2.2";
   name = "${targetPrefix}ghc-${version}";
 
···
     sha256 = "1z05vkpaj54xdypmaml50hgsdpw29dhbs2r7magx0cm199iw73mv";
   };
 
+  enableParallelBuilding = true;
+
+  outputs = [ "out" "doc" ];
+
+  patches = [
+    (fetchpatch { # Fix STRIP to be substituted from configure
+      url = "https://git.haskell.org/ghc.git/commitdiff_plain/2fc8ce5f0c8c81771c26266ac0b150ca9b75c5f3";
+      sha256 = "03253ci40np1v6k0wmi4aypj3nmj3rdyvb1k6rwqipb30nfc719f";
+    })
+  ];
+
   postPatch = "patchShebangs .";
 
+  # GHC is a bit confused on its cross terminology.
   preConfigure = ''
+    for env in $(env | grep '^TARGET_' | sed -E 's|\+?=.*||'); do
+      export "''${env#TARGET_}=''${!env}"
+    done
+    # GHC is a bit confused on its cross terminology, as these would normally be
+    # the *host* tools.
+    export CC="${targetCC}/bin/${targetCC.targetPrefix}cc"
+    export CXX="${targetCC}/bin/${targetCC.targetPrefix}cxx"
+    # Use gold to work around https://sourceware.org/bugzilla/show_bug.cgi?id=16177
+    export LD="${targetCC.bintools}/bin/${targetCC.bintools.targetPrefix}ld${stdenv.lib.optionalString targetPlatform.isArm ".gold"}"
+    export AS="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}as"
+    export AR="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ar"
+    export NM="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}nm"
+    export RANLIB="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ranlib"
+    export READELF="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}readelf"
+    export STRIP="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}strip"
+
+    echo -n "${buildMK}" > mk/build.mk
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
   '' + stdenv.lib.optionalString (!stdenv.isDarwin) ''
-    export NIX_LDFLAGS="$NIX_LDFLAGS -rpath $out/lib/ghc-${version}"
+    export NIX_LDFLAGS+=" -rpath $out/lib/ghc-${version}"
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     export NIX_LDFLAGS+=" -no_dtrace_dof"
-  '' + stdenv.lib.optionalString enableIntegerSimple ''
-    echo "INTEGER_LIBRARY=integer-simple" > mk/build.mk
-  '' + stdenv.lib.optionalString (targetPlatform != hostPlatform) ''
-    sed 's|#BuildFlavour  = quick-cross|BuildFlavour  = perf-cross|' mk/build.mk.sample > mk/build.mk
   '';
 
-  buildInputs = [ alex autoconf automake ghc happy hscolour perl python3 sphinx ] ++ stdenv.lib.optionals (targetPlatform.isArm || targetPlatform.isAarch64) [ llvm_39 ];
-
-  enableParallelBuilding = true;
-
+  # TODO(@Ericson2314): Always pass "--target" and always prefix.
+  configurePlatforms = [ "build" "host" ]
+    ++ stdenv.lib.optional (targetPlatform != hostPlatform) "target";
+  # `--with` flags for libraries needed for RTS linker
   configureFlags = [
-    "CC=${stdenv.cc}/bin/cc"
+    "--datadir=$doc/share/doc/ghc"
     "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
-    "--datadir=$doc/share/doc/ghc"
-  ] ++ stdenv.lib.optional (! enableIntegerSimple) [
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && ! enableIntegerSimple) [
     "--with-gmp-includes=${gmp.dev}/include" "--with-gmp-libraries=${gmp.out}/lib"
-  ] ++ stdenv.lib.optional stdenv.isDarwin [
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && hostPlatform.libc != "glibc") [
     "--with-iconv-includes=${libiconv}/include" "--with-iconv-libraries=${libiconv}/lib"
-  ] ++ stdenv.lib.optional stdenv.isArm [
-    "LD=${stdenv.cc}/bin/ld.gold"
+  ] ++ stdenv.lib.optionals (targetPlatform != hostPlatform) [
+    "--enable-bootstrap-with-devel-snapshot"
+  ] ++ stdenv.lib.optionals (targetPlatform.isArm) [
+    "CFLAGS=-fuse-ld=gold"
+    "CONF_GCC_LINKER_OPTS_STAGE1=-fuse-ld=gold"
+    "CONF_GCC_LINKER_OPTS_STAGE2=-fuse-ld=gold"
+  ] ++ stdenv.lib.optionals (targetPlatform.isDarwin && targetPlatform.isAarch64) [
+    # fix for iOS: https://www.reddit.com/r/haskell/comments/4ttdz1/building_an_osxi386_to_iosarm64_cross_compiler/d5qvd67/
+    "--disable-large-address-space"
   ];
 
+  # Hack to make sure we never to the relaxation `$PATH` and hooks support for
+  # compatability. This will be replaced with something clearer in a future
+  # masss-rebuild.
+  crossConfig = true;
+
+  nativeBuildInputs = [ alex autoconf autoreconfHook automake ghc happy hscolour perl python3 sphinx ];
+
+  # For building runtime libs
+  depsBuildTarget = toolsForTarget;
+
+  buildInputs = libDeps hostPlatform;
+
+  propagatedBuildInputs = [ targetPackages.stdenv.cc ]
+    ++ stdenv.lib.optional useLLVM llvmPackages.llvm;
+
+  depsTargetTarget = map stdenv.lib.getDev (libDeps targetPlatform);
+  depsTargetTargetPropagated = map (stdenv.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" ] ++ stdenv.lib.optional (!targetPlatform.isDarwin) "--keep-file-symbols";
 
   checkTarget = "test";
 
+  # zsh and other shells are smart about `{ghc}` but bash isn't, and doesn't
+  # treat that as a unary `{x,y,z,..}` repetition.
   postInstall = ''
     paxmark m $out/lib/${name}/bin/${if targetPlatform != hostPlatform then "ghc" else "{ghc,haddock}"}
 
···
     done
   '';
 
-  outputs = [ "out" "doc" ];
-
   passthru = {
     inherit bootPkgs targetPrefix;
-  } // stdenv.lib.optionalAttrs (targetPlatform != buildPlatform) {
-    crossCompiler = selfPkgs.ghc.override {
-      cross = targetPlatform;
-      bootPkgs = selfPkgs;
-    };
+
+    inherit llvmPackages;
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
   };
 
   meta = {
···
     inherit (ghc.meta) license platforms;
   };
 
-} // stdenv.lib.optionalAttrs (cross != null) {
-  configureFlags = [
-    "CC=${stdenv.cc}/bin/${cross.config}-cc"
-    "LD=${stdenv.cc.bintools}/bin/${cross.config}-ld"
-    "AR=${stdenv.cc.bintools}/bin/${cross.config}-ar"
-    "NM=${stdenv.cc.bintools}/bin/${cross.config}-nm"
-    "RANLIB=${stdenv.cc.bintools}/bin/${cross.config}-ranlib"
-    "--target=${cross.config}"
-    "--enable-bootstrap-with-devel-snapshot"
-  ] ++
-    # fix for iOS: https://www.reddit.com/r/haskell/comments/4ttdz1/building_an_osxi386_to_iosarm64_cross_compiler/d5qvd67/
-    stdenv.lib.optional (cross.config or null == "aarch64-apple-darwin14") "--disable-large-address-space";
-
-  configurePlatforms = [];
-
-  passthru = {
-    inherit bootPkgs cross;
-    cc = "${stdenv.cc}/bin/${cross.config}-cc";
-    ld = "${stdenv.cc}/bin/${cross.config}-ld";
-  };
-})
+}

pkgs/development/compilers/ghc/8.4.1.nix

···
 { stdenv, targetPackages
 , buildPlatform, hostPlatform, targetPlatform
-, selfPkgs, cross ? null
 
 # build-tools
 , bootPkgs, alex, happy
 , autoconf, automake, coreutils, fetchgit, perl, python3
 
-, libiconv ? null, ncurses
+, libffi, libiconv ? null, ncurses
+
+, useLLVM ? !targetPlatform.isx86
+, # LLVM is conceptually a run-time-only depedendency, but for
+  # non-x86, we need LLVM to bootstrap later stages, so it becomes a
+  # build-time dependency too.
+  buildLlvmPackages, 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 ? false, gmp ? null
 
+, # If enabled, use -fPIC when compiling static libs.
+  enableRelocatedStaticLibs ? targetPlatform != hostPlatform
+
+, # Whether to build dynamic libs for the standard library (on the target
+  # platform). Static libs are always built.
+  enableShared ? true
+
 , version ? "8.4.20180115"
 }:
 
···
 let
   inherit (bootPkgs) ghc;
 
-  rev = "3e3a096885c0fcd0703edbeffb4e47f5cbd8f4cc";
-
   # TODO(@Ericson2314) Make unconditional
   targetPrefix = stdenv.lib.optionalString
     (targetPlatform != hostPlatform)
     "${targetPlatform.config}-";
+
+  buildMK = ''
+    DYNAMIC_GHC_PROGRAMS = ${if enableShared then "YES" else "NO"}
+  '' + stdenv.lib.optionalString enableIntegerSimple ''
+    INTEGER_LIBRARY = integer-simple
+  '' + stdenv.lib.optionalString (targetPlatform != hostPlatform) ''
+    BuildFlavour = perf-cross
+    Stage1Only = YES
+    HADDOCK_DOCS = NO
+    BUILD_SPHINX_HTML = NO
+    BUILD_SPHINX_PDF = NO
+  '' + stdenv.lib.optionalString enableRelocatedStaticLibs ''
+    GhcLibHcOpts += -fPIC
+    GhcRtsHcOpts += -fPIC
+  '';
+
+  # Splicer will pull out correct variations
+  libDeps = platform: [ ncurses ]
+    ++ stdenv.lib.optional (!enableIntegerSimple) gmp
+    ++ stdenv.lib.optional (platform.libc != "glibc") libiconv;
+
+  toolsForTarget =
+    if hostPlatform == buildPlatform then
+      [ targetPackages.stdenv.cc ] ++ stdenv.lib.optional useLLVM llvmPackages.llvm
+    else assert targetPlatform == hostPlatform; # build != host == target
+      [ stdenv.cc ] ++ stdenv.lib.optional useLLVM buildLlvmPackages.llvm;
+
+  targetCC = builtins.head toolsForTarget;
+
 in
-stdenv.mkDerivation (rec {
-  inherit version rev;
+stdenv.mkDerivation rec {
+  inherit version;
+  inherit (src) rev;
   name = "${targetPrefix}ghc-${version}";
 
   src = fetchgit {
     url = "git://git.haskell.org/ghc.git";
-    inherit rev;
+    rev = "3e3a096885c0fcd0703edbeffb4e47f5cbd8f4cc";
     sha256 = "06slymbsd7vsfp4hh40v7cxf7nmp0kvlni2wfq7ag5wlqh04slgs";
   };
 
+  enableParallelBuilding = true;
+
+  outputs = [ "out" "doc" ];
+
   postPatch = "patchShebangs .";
 
+  # GHC is a bit confused on its cross terminology.
   preConfigure = ''
+    for env in $(env | grep '^TARGET_' | sed -E 's|\+?=.*||'); do
+      export "''${env#TARGET_}=''${!env}"
+    done
+    # GHC is a bit confused on its cross terminology, as these would normally be
+    # the *host* tools.
+    export CC="${targetCC}/bin/${targetCC.targetPrefix}cc"
+    export CXX="${targetCC}/bin/${targetCC.targetPrefix}cxx"
+    # Use gold to work around https://sourceware.org/bugzilla/show_bug.cgi?id=16177
+    export LD="${targetCC.bintools}/bin/${targetCC.bintools.targetPrefix}ld${stdenv.lib.optionalString targetPlatform.isArm ".gold"}"
+    export AS="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}as"
+    export AR="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ar"
+    export NM="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}nm"
+    export RANLIB="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ranlib"
+    export READELF="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}readelf"
+    export STRIP="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}strip"
+
+    echo -n "${buildMK}" > mk/build.mk
     echo ${version} >VERSION
-    echo ${rev} >GIT_COMMIT_ID
+    echo ${src.rev} >GIT_COMMIT_ID
     ./boot
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
   '' + stdenv.lib.optionalString (!stdenv.isDarwin) ''
-    export NIX_LDFLAGS="$NIX_LDFLAGS -rpath $out/lib/ghc-${version}"
+    export NIX_LDFLAGS+=" -rpath $out/lib/ghc-${version}"
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     export NIX_LDFLAGS+=" -no_dtrace_dof"
-  '' + stdenv.lib.optionalString enableIntegerSimple ''
-    echo "INTEGER_LIBRARY=integer-simple" > mk/build.mk
-  '' + stdenv.lib.optionalString (targetPlatform != hostPlatform) ''
-    sed 's|#BuildFlavour  = quick-cross|BuildFlavour  = perf-cross|' mk/build.mk.sample > mk/build.mk
   '';
 
-  buildInputs = [ ghc perl autoconf automake happy alex python3 ];
-
-  enableParallelBuilding = true;
-
+  # TODO(@Ericson2314): Always pass "--target" and always prefix.
+  configurePlatforms = [ "build" "host" ]
+    ++ stdenv.lib.optional (targetPlatform != hostPlatform) "target";
+  # `--with` flags for libraries needed for RTS linker
   configureFlags = [
-    "CC=${stdenv.cc}/bin/cc"
+    "--datadir=$doc/share/doc/ghc"
     "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
-    "--datadir=$doc/share/doc/ghc"
-  ] ++ stdenv.lib.optional (! enableIntegerSimple) [
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && ! enableIntegerSimple) [
     "--with-gmp-includes=${gmp.dev}/include" "--with-gmp-libraries=${gmp.out}/lib"
-  ] ++ stdenv.lib.optional stdenv.isDarwin [
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && hostPlatform.libc != "glibc") [
     "--with-iconv-includes=${libiconv}/include" "--with-iconv-libraries=${libiconv}/lib"
+  ] ++ stdenv.lib.optionals (targetPlatform != hostPlatform) [
+    "--enable-bootstrap-with-devel-snapshot"
+  ] ++ stdenv.lib.optionals (targetPlatform.isArm) [
+    "CFLAGS=-fuse-ld=gold"
+    "CONF_GCC_LINKER_OPTS_STAGE1=-fuse-ld=gold"
+    "CONF_GCC_LINKER_OPTS_STAGE2=-fuse-ld=gold"
+  ] ++ stdenv.lib.optionals (targetPlatform.isDarwin && targetPlatform.isAarch64) [
+    # fix for iOS: https://www.reddit.com/r/haskell/comments/4ttdz1/building_an_osxi386_to_iosarm64_cross_compiler/d5qvd67/
+    "--disable-large-address-space"
   ];
 
+  # Hack to make sure we never to the relaxation `$PATH` and hooks support for
+  # compatability. This will be replaced with something clearer in a future
+  # masss-rebuild.
+  crossConfig = true;
+
+  nativeBuildInputs = [ ghc perl autoconf automake happy alex python3 ];
+
+  # For building runtime libs
+  depsBuildTarget = toolsForTarget;
+
+  buildInputs = libDeps hostPlatform;
+
+  propagatedBuildInputs = [ targetPackages.stdenv.cc ]
+    ++ stdenv.lib.optional useLLVM llvmPackages.llvm;
+
+  depsTargetTarget = map stdenv.lib.getDev (libDeps targetPlatform);
+  depsTargetTargetPropagated = map (stdenv.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" ] ++ stdenv.lib.optional (!targetPlatform.isDarwin) "--keep-file-symbols";
 
   checkTarget = "test";
 
+  # zsh and other shells are smart about `{ghc}` but bash isn't, and doesn't
+  # treat that as a unary `{x,y,z,..}` repetition.
   postInstall = ''
     paxmark m $out/lib/${name}/bin/${if targetPlatform != hostPlatform then "ghc" else "{ghc,haddock}"}
 
···
     done
   '';
 
-  outputs = [ "out" "doc" ];
-
   passthru = {
     inherit bootPkgs targetPrefix;
-  } // stdenv.lib.optionalAttrs (targetPlatform != buildPlatform) {
-    crossCompiler = selfPkgs.ghc.override {
-      cross = targetPlatform;
-      bootPkgs = selfPkgs;
-    };
+
+    inherit llvmPackages;
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
   };
 
   meta = {
···
     inherit (ghc.meta) license platforms;
   };
 
-} // stdenv.lib.optionalAttrs (cross != null) {
-  configureFlags = [
-    "CC=${stdenv.cc}/bin/${cross.config}-cc"
-    "LD=${stdenv.cc.bintools}/bin/${cross.config}-ld"
-    "AR=${stdenv.cc.bintools}/bin/${cross.config}-ar"
-    "NM=${stdenv.cc.bintools}/bin/${cross.config}-nm"
-    "RANLIB=${stdenv.cc.bintools}/bin/${cross.config}-ranlib"
-    "--target=${cross.config}"
-    "--enable-bootstrap-with-devel-snapshot"
-  ] ++
-    # fix for iOS: https://www.reddit.com/r/haskell/comments/4ttdz1/building_an_osxi386_to_iosarm64_cross_compiler/d5qvd67/
-    stdenv.lib.optional (cross.config or null == "aarch64-apple-darwin14") "--disable-large-address-space";
-
-  configurePlatforms = [];
-
-  passthru = {
-    inherit bootPkgs cross;
-    cc = "${stdenv.cc}/bin/${cross.config}-cc";
-    ld = "${stdenv.cc}/bin/${cross.config}-ld";
-  };
-})
+}

pkgs/development/compilers/ghc/head.nix

···
 { stdenv, targetPackages
 , buildPlatform, hostPlatform, targetPlatform
-, selfPkgs, cross ? null
 
 # build-tools
 , bootPkgs, alex, happy
 , autoconf, automake, coreutils, fetchgit, perl, python3
 
-, libiconv ? null, ncurses
+, libffi, libiconv ? null, ncurses
+
+, useLLVM ? !targetPlatform.isx86
+, # LLVM is conceptually a run-time-only depedendency, but for
+  # non-x86, we need LLVM to bootstrap later stages, so it becomes a
+  # build-time dependency too.
+  buildLlvmPackages, 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 ? false, gmp ? null
 
-, version ? "8.5.20171209"
+, # If enabled, use -fPIC when compiling static libs.
+  enableRelocatedStaticLibs ? targetPlatform != hostPlatform
+
+, # Whether to build dynamic libs for the standard library (on the target
+  # platform). Static libs are always built.
+  enableShared ? true
+
+, version ? "8.5.20180118"
 }:
 
 assert !enableIntegerSimple -> gmp != null;
···
 let
   inherit (bootPkgs) ghc;
 
-  rev = "4335c07ca7e64624819b22644d7591853826bd75";
-
   # TODO(@Ericson2314) Make unconditional
   targetPrefix = stdenv.lib.optionalString
     (targetPlatform != hostPlatform)
     "${targetPlatform.config}-";
+
+  buildMK = ''
+    DYNAMIC_GHC_PROGRAMS = ${if enableShared then "YES" else "NO"}
+  '' + stdenv.lib.optionalString enableIntegerSimple ''
+    INTEGER_LIBRARY = integer-simple
+  '' + stdenv.lib.optionalString (targetPlatform != hostPlatform) ''
+    BuildFlavour = perf-cross
+    Stage1Only = YES
+    HADDOCK_DOCS = NO
+    BUILD_SPHINX_HTML = NO
+    BUILD_SPHINX_PDF = NO
+  '' + stdenv.lib.optionalString enableRelocatedStaticLibs ''
+    GhcLibHcOpts += -fPIC
+    GhcRtsHcOpts += -fPIC
+  '';
+
+  # Splicer will pull out correct variations
+  libDeps = platform: [ ncurses ]
+    ++ stdenv.lib.optional (!enableIntegerSimple) gmp
+    ++ stdenv.lib.optional (platform.libc != "glibc") libiconv;
+
+  toolsForTarget =
+    if hostPlatform == buildPlatform then
+      [ targetPackages.stdenv.cc ] ++ stdenv.lib.optional useLLVM llvmPackages.llvm
+    else assert targetPlatform == hostPlatform; # build != host == target
+      [ stdenv.cc ] ++ stdenv.lib.optional useLLVM buildLlvmPackages.llvm;
+
+  targetCC = builtins.head toolsForTarget;
+
 in
-stdenv.mkDerivation (rec {
-  inherit version rev;
+stdenv.mkDerivation rec {
+  inherit version;
+  inherit (src) rev;
   name = "${targetPrefix}ghc-${version}";
 
   src = fetchgit {
     url = "git://git.haskell.org/ghc.git";
-    inherit rev;
-    sha256 = "19csad94sk0bw2nj97ppmnwh4c193jg0jmg5w2sx9rqm9ih4yg85";
+    rev = "e1d4140be4d2a1508015093b69e1ef53516e1eb6";
+    sha256 = "1gdcr10dd968d40qgljdwx9vfkva3yrvjm9a4nis7whaaac3ag58";
   };
 
+  enableParallelBuilding = true;
+
+  outputs = [ "out" "doc" ];
+
   postPatch = "patchShebangs .";
 
+  # GHC is a bit confused on its cross terminology.
   preConfigure = ''
+    for env in $(env | grep '^TARGET_' | sed -E 's|\+?=.*||'); do
+      export "''${env#TARGET_}=''${!env}"
+    done
+    # GHC is a bit confused on its cross terminology, as these would normally be
+    # the *host* tools.
+    export CC="${targetCC}/bin/${targetCC.targetPrefix}cc"
+    export CXX="${targetCC}/bin/${targetCC.targetPrefix}cxx"
+    # Use gold to work around https://sourceware.org/bugzilla/show_bug.cgi?id=16177
+    export LD="${targetCC.bintools}/bin/${targetCC.bintools.targetPrefix}ld${stdenv.lib.optionalString targetPlatform.isArm ".gold"}"
+    export AS="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}as"
+    export AR="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ar"
+    export NM="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}nm"
+    export RANLIB="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}ranlib"
+    export READELF="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}readelf"
+    export STRIP="${targetCC.bintools.bintools}/bin/${targetCC.bintools.targetPrefix}strip"
+
+    echo -n "${buildMK}" > mk/build.mk
     echo ${version} >VERSION
-    echo ${rev} >GIT_COMMIT_ID
+    echo ${src.rev} >GIT_COMMIT_ID
     ./boot
     sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
   '' + stdenv.lib.optionalString (!stdenv.isDarwin) ''
-    export NIX_LDFLAGS="$NIX_LDFLAGS -rpath $out/lib/ghc-${version}"
+    export NIX_LDFLAGS+=" -rpath $out/lib/ghc-${version}"
   '' + stdenv.lib.optionalString stdenv.isDarwin ''
     export NIX_LDFLAGS+=" -no_dtrace_dof"
-  '' + stdenv.lib.optionalString enableIntegerSimple ''
-    echo "INTEGER_LIBRARY=integer-simple" > mk/build.mk
-  '' + stdenv.lib.optionalString (targetPlatform != hostPlatform) ''
-    sed 's|#BuildFlavour  = quick-cross|BuildFlavour  = perf-cross|' mk/build.mk.sample > mk/build.mk
   '';
 
-  buildInputs = [ ghc perl autoconf automake happy alex python3 ];
-
-  enableParallelBuilding = true;
-
+  # TODO(@Ericson2314): Always pass "--target" and always prefix.
+  configurePlatforms = [ "build" "host" ]
+    ++ stdenv.lib.optional (targetPlatform != hostPlatform) "target";
+  # `--with` flags for libraries needed for RTS linker
   configureFlags = [
-    "CC=${stdenv.cc}/bin/cc"
-    "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
     "--datadir=$doc/share/doc/ghc"
-  ] ++ stdenv.lib.optional (! enableIntegerSimple) [
+    "--with-curses-includes=${ncurses.dev}/include" "--with-curses-libraries=${ncurses.out}/lib"
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && ! enableIntegerSimple) [
     "--with-gmp-includes=${gmp.dev}/include" "--with-gmp-libraries=${gmp.out}/lib"
-  ] ++ stdenv.lib.optional stdenv.isDarwin [
+  ] ++ stdenv.lib.optional (targetPlatform == hostPlatform && hostPlatform.libc != "glibc") [
     "--with-iconv-includes=${libiconv}/include" "--with-iconv-libraries=${libiconv}/lib"
+  ] ++ stdenv.lib.optionals (targetPlatform != hostPlatform) [
+    "--enable-bootstrap-with-devel-snapshot"
+  ] ++ stdenv.lib.optionals (targetPlatform.isArm) [
+    "CFLAGS=-fuse-ld=gold"
+    "CONF_GCC_LINKER_OPTS_STAGE1=-fuse-ld=gold"
+    "CONF_GCC_LINKER_OPTS_STAGE2=-fuse-ld=gold"
+  ] ++ stdenv.lib.optionals (targetPlatform.isDarwin && targetPlatform.isAarch64) [
+    # fix for iOS: https://www.reddit.com/r/haskell/comments/4ttdz1/building_an_osxi386_to_iosarm64_cross_compiler/d5qvd67/
+    "--disable-large-address-space"
   ];
 
+  # Hack to make sure we never to the relaxation `$PATH` and hooks support for
+  # compatability. This will be replaced with something clearer in a future
+  # masss-rebuild.
+  crossConfig = true;
+
+  nativeBuildInputs = [ ghc perl autoconf automake happy alex python3 ];
+
+  # For building runtime libs
+  depsBuildTarget = toolsForTarget;
+
+  buildInputs = libDeps hostPlatform;
+
+  propagatedBuildInputs = [ targetPackages.stdenv.cc ]
+    ++ stdenv.lib.optional useLLVM llvmPackages.llvm;
+
+  depsTargetTarget = map stdenv.lib.getDev (libDeps targetPlatform);
+  depsTargetTargetPropagated = map (stdenv.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" ] ++ stdenv.lib.optional (!targetPlatform.isDarwin) "--keep-file-symbols";
 
   checkTarget = "test";
 
+  # zsh and other shells are smart about `{ghc}` but bash isn't, and doesn't
+  # treat that as a unary `{x,y,z,..}` repetition.
   postInstall = ''
     paxmark m $out/lib/${name}/bin/${if targetPlatform != hostPlatform then "ghc" else "{ghc,haddock}"}
 
···
     done
   '';
 
-  outputs = [ "out" "doc" ];
-
   passthru = {
     inherit bootPkgs targetPrefix;
-  } // stdenv.lib.optionalAttrs (targetPlatform != buildPlatform) {
-    crossCompiler = selfPkgs.ghc.override {
-      cross = targetPlatform;
-      bootPkgs = selfPkgs;
-    };
+
+    inherit llvmPackages;
+
+    # Our Cabal compiler name
+    haskellCompilerName = "ghc";
   };
 
   meta = {
···
     inherit (ghc.meta) license platforms;
   };
 
-} // stdenv.lib.optionalAttrs (cross != null) {
-  configureFlags = [
-    "CC=${stdenv.cc}/bin/${cross.config}-cc"
-    "LD=${stdenv.cc.bintools}/bin/${cross.config}-ld"
-    "AR=${stdenv.cc.bintools}/bin/${cross.config}-ar"
-    "NM=${stdenv.cc.bintools}/bin/${cross.config}-nm"
-    "RANLIB=${stdenv.cc.bintools}/bin/${cross.config}-ranlib"
-    "--target=${cross.config}"
-    "--enable-bootstrap-with-devel-snapshot"
-  ] ++
-    # fix for iOS: https://www.reddit.com/r/haskell/comments/4ttdz1/building_an_osxi386_to_iosarm64_cross_compiler/d5qvd67/
-    stdenv.lib.optional (cross.config or null == "aarch64-apple-darwin14") "--disable-large-address-space";
-
-  configurePlatforms = [];
-
-  passthru = {
-    inherit bootPkgs cross;
-    cc = "${stdenv.cc}/bin/${cross.config}-cc";
-    ld = "${stdenv.cc}/bin/${cross.config}-ld";
-  };
-})
+}

pkgs/development/haskell-modules/default.nix

···
 { pkgs, stdenv, lib, haskellLib, ghc, all-cabal-hashes
+, buildHaskellPackages
 , compilerConfig ? (self: super: {})
 , packageSetConfig ? (self: super: {})
 , overrides ? (self: super: {})
···
 
   haskellPackages = pkgs.callPackage makePackageSet {
     package-set = initialPackages;
-    inherit stdenv haskellLib ghc extensible-self;
+    inherit stdenv haskellLib ghc buildHaskellPackages extensible-self;
   };
 
   commonConfiguration = configurationCommon { inherit pkgs haskellLib; };

pkgs/development/haskell-modules/generic-builder.nix

···
-{ stdenv, buildPackages, ghc
+{ stdenv, buildPackages, buildHaskellPackages, ghc
 , jailbreak-cabal, hscolour, cpphs, nodejs
 , buildPlatform, hostPlatform
 }:
···
                   then "package-db"
                   else "package-conf";
 
-  nativeGhc = if isCross || isGhcjs then ghc.bootPkgs.ghc else ghc;
+  # GHC used for building Setup.hs
+  #
+  # Same as our GHC, unless we're cross, in which case it is native GHC with the
+  # same version, or ghcjs, in which case its the ghc used to build ghcjs.
+  nativeGhc = buildHaskellPackages.ghc;
   nativePackageDbFlag = if versionOlder "7.6" nativeGhc.version
                         then "package-db"
                         else "package-conf";
···
   ] ++ crossCabalFlags);
 
   setupCompileFlags = [
-    (optionalString (!coreSetup) "-${packageDbFlag}=$packageConfDir")
-    (optionalString isGhcjs "-build-runner")
+    (optionalString (!coreSetup) "-${nativePackageDbFlag}=$packageConfDir")
     (optionalString (isGhcjs || isHaLVM || versionOlder "7.8" ghc.version) "-j$NIX_BUILD_CORES")
     # https://github.com/haskell/cabal/issues/2398
     (optionalString (versionOlder "7.10" ghc.version && !isHaLVM) "-threaded")
···
   allPkgconfigDepends = pkgconfigDepends ++ libraryPkgconfigDepends ++ executablePkgconfigDepends ++
                         optionals doCheck testPkgconfigDepends ++ optionals doBenchmark benchmarkPkgconfigDepends;
 
-  nativeBuildInputs = optional (allPkgconfigDepends != []) pkgconfig ++
-                      buildTools ++ libraryToolDepends ++ executableToolDepends ++ [ removeReferencesTo ];
+  nativeBuildInputs = [ ghc nativeGhc removeReferencesTo ] ++ optional (allPkgconfigDepends != []) pkgconfig ++
+                      buildTools ++ libraryToolDepends ++ executableToolDepends;
   propagatedBuildInputs = buildDepends ++ libraryHaskellDepends ++ executableHaskellDepends;
   otherBuildInputs = setupHaskellDepends ++ extraLibraries ++ librarySystemDepends ++ executableSystemDepends ++
                      optionals (allPkgconfigDepends != []) allPkgconfigDepends ++
                      optionals doCheck (testDepends ++ testHaskellDepends ++ testSystemDepends ++ testToolDepends) ++
-                     # ghcjs's hsc2hs calls out to the native hsc2hs
-                     optional isGhcjs nativeGhc ++
                      optionals doBenchmark (benchmarkDepends ++ benchmarkHaskellDepends ++ benchmarkSystemDepends ++ benchmarkToolDepends);
   allBuildInputs = propagatedBuildInputs ++ otherBuildInputs;
 
···
 
   ghcEnv = ghc.withPackages (p: haskellBuildInputs);
 
-  setupBuilder = if isCross then "${nativeGhc}/bin/ghc" else ghcCommand;
   setupCommand = "./Setup";
+
   ghcCommand' = if isGhcjs then "ghcjs" else "ghc";
   ghcCommand = "${ghc.targetPrefix}${ghcCommand'}";
   ghcCommandCaps= toUpper ghcCommand';
 
+  nativeGhcCommand = "${nativeGhc.targetPrefix}ghc";
+
 in
 
 assert allPkgconfigDepends != [] -> pkgconfig != null;
···
     runHook preSetupCompilerEnvironment
 
     echo "Build with ${ghc}."
-    export PATH="${ghc}/bin:$PATH"
     ${optionalString (hasActiveLibrary && hyperlinkSource) "export PATH=${hscolour}/bin:$PATH"}
 
     packageConfDir="$TMPDIR/package.conf.d"
···
     done
 
     echo setupCompileFlags: $setupCompileFlags
-    ${setupBuilder} $setupCompileFlags --make -o Setup -odir $TMPDIR -hidir $TMPDIR $i
+    ${nativeGhcCommand} $setupCompileFlags --make -o Setup -odir $TMPDIR -hidir $TMPDIR $i
 
     runHook postCompileBuildDriver
   '';
 
+  # Cabal takes flags like `--configure-option=--host=...` instead
+  configurePlatforms = [];
   inherit configureFlags;
 
   configurePhase = ''

pkgs/development/haskell-modules/make-package-set.nix

···
 { # package-set used for build tools (all of nixpkgs)
   buildPackages
 
+, # A haskell package set for Setup.hs, compiler plugins, and similar
+  # build-time uses.
+  buildHaskellPackages
+
 , # package-set used for non-haskell dependencies (all of nixpkgs)
   pkgs
 
···
 , # compiler to use
   ghc
 
-, # A function that takes `{ pkgs, stdenv, callPackage }` as the first arg and `self`
-  # as second, and returns a set of haskell packages
+, # A function that takes `{ pkgs, stdenv, callPackage }` as the first arg and
+  # `self` as second, and returns a set of haskell packages
   package-set
 
 , # The final, fully overriden package set usable with the nixpkgs fixpoint
···
   inherit (stdenv.lib) fix' extends makeOverridable;
   inherit (haskellLib) overrideCabal;
 
-  buildHaskellPackages = if hostPlatform != buildPlatform
-                         then self.ghc.bootPkgs
-                         else self;
-
   mkDerivationImpl = pkgs.callPackage ./generic-builder.nix {
     inherit stdenv;
     nodejs = buildPackages.nodejs-slim;
+    inherit buildHaskellPackages;
+    inherit (self) ghc;
     inherit (buildHaskellPackages) jailbreak-cabal;
-    inherit (self) ghc;
     hscolour = overrideCabal buildHaskellPackages.hscolour (drv: {
       isLibrary = false;
       doHaddock = false;
···
       installPhase = ''
         export HOME="$TMP"
         mkdir -p "$out"
-        cabal2nix --compiler=${self.ghc.name} --system=${stdenv.system} ${sha256Arg} "${src}" > "$out/default.nix"
+        cabal2nix --compiler=${ghc.haskellCompilerName} --system=${stdenv.system} ${sha256Arg} "${src}" > "$out/default.nix"
       '';
   };
 

pkgs/top-level/haskell-packages.nix

···
-{ pkgs, lib, newScope, stdenv, buildPlatform, targetPlatform, cabal-install }:
+{ buildPackages, pkgs
+, newScope, stdenv
+, buildPlatform, targetPlatform
+}:
 
 let
   # These are attributes in compiler and packages that don't support integer-simple.
···
     ghc7103 = callPackage ../development/compilers/ghc/7.10.3.nix rec {
       bootPkgs = packages.ghc7103Binary;
       inherit (bootPkgs) hscolour;
+      buildLlvmPackages = buildPackages.llvmPackages_35;
+      llvmPackages = pkgs.llvmPackages_35;
     };
     ghc802 = callPackage ../development/compilers/ghc/8.0.2.nix rec {
       bootPkgs = packages.ghc7103Binary;
       inherit (bootPkgs) hscolour;
       sphinx = pkgs.python27Packages.sphinx;
+      buildLlvmPackages = buildPackages.llvmPackages_37;
+      llvmPackages = pkgs.llvmPackages_37;
     };
     ghc822 = callPackage ../development/compilers/ghc/8.2.2.nix rec {
       bootPkgs = packages.ghc821Binary;
       inherit (bootPkgs) hscolour alex happy;
       inherit buildPlatform targetPlatform;
       sphinx = pkgs.python3Packages.sphinx;
-      selfPkgs = packages.ghc822;
+      buildLlvmPackages = buildPackages.llvmPackages_39;
+      llvmPackages = pkgs.llvmPackages_39;
     };
     ghc841 = callPackage ../development/compilers/ghc/8.4.1.nix rec {
       bootPkgs = packages.ghc821Binary;
       inherit (bootPkgs) alex happy;
-      inherit buildPlatform targetPlatform;
-      selfPkgs = packages.ghc841;
+      buildLlvmPackages = buildPackages.llvmPackages_5;
+      llvmPackages = pkgs.llvmPackages_5;
     };
     ghcHEAD = callPackage ../development/compilers/ghc/head.nix rec {
       bootPkgs = packages.ghc821Binary;
       inherit (bootPkgs) alex happy;
-      inherit buildPlatform targetPlatform;
-      selfPkgs = packages.ghcHEAD;
+      buildLlvmPackages = buildPackages.llvmPackages_5;
+      llvmPackages = pkgs.llvmPackages_5;
     };
     ghcjs = packages.ghc7103.callPackage ../development/compilers/ghcjs {
       bootPkgs = packages.ghc7103;
-      inherit cabal-install;
+      inherit (pkgs) cabal-install;
     };
     ghcjsHEAD = packages.ghc802.callPackage ../development/compilers/ghcjs/head.nix {
       bootPkgs = packages.ghc802;
-      inherit cabal-install;
+      inherit (pkgs) cabal-install;
     };
     ghcHaLVM240 = callPackage ../development/compilers/halvm/2.4.0.nix rec {
       bootPkgs = packages.ghc7103Binary;
···
 
     # The integer-simple attribute set contains all the GHC compilers
     # build with integer-simple instead of integer-gmp.
-    integer-simple =
-      let integerSimpleGhcNames =
-            pkgs.lib.filter (name: ! builtins.elem name integerSimpleExcludes)
-                            (pkgs.lib.attrNames compiler);
-          integerSimpleGhcs = pkgs.lib.genAttrs integerSimpleGhcNames
-                                (name: compiler."${name}".override { enableIntegerSimple = true; });
-      in pkgs.recurseIntoAttrs (integerSimpleGhcs // {
-           ghcHEAD = integerSimpleGhcs.ghcHEAD.override { selfPkgs = packages.integer-simple.ghcHEAD; };
-         });
-
+    integer-simple = let
+      integerSimpleGhcNames = pkgs.lib.filter
+        (name: ! builtins.elem name integerSimpleExcludes)
+        (pkgs.lib.attrNames compiler);
+    in pkgs.recurseIntoAttrs (pkgs.lib.genAttrs
+      integerSimpleGhcNames
+      (name: compiler."${name}".override { enableIntegerSimple = true; }));
   };
 
-  packages = {
+  # Always get compilers from `buildPackages`
+  packages = let bh = buildPackages.haskell; in {
 
     ghc7103 = callPackage ../development/haskell-modules {
-      ghc = compiler.ghc7103;
+      buildHaskellPackages = bh.packages.ghc7103;
+      ghc = bh.compiler.ghc7103;
       compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-7.10.x.nix { };
     };
     ghc7103Binary = callPackage ../development/haskell-modules {
-      ghc = compiler.ghc7103Binary;
+      buildHaskellPackages = bh.packages.ghc7103Binary;
+      ghc = bh.compiler.ghc7103Binary;
       compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-7.10.x.nix { };
     };
     ghc802 = callPackage ../development/haskell-modules {
-      ghc = compiler.ghc802;
+      buildHaskellPackages = bh.packages.ghc802;
+      ghc = bh.compiler.ghc802;
       compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-8.0.x.nix { };
     };
-    ghc822 = callPackage ../development/haskell-modules {
-      ghc = compiler.ghc822;
+    ghc821Binary = callPackage ../development/haskell-modules {
+      buildHaskellPackages = bh.packages.ghc821Binary;
+      ghc = bh.compiler.ghc821Binary;
       compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-8.2.x.nix { };
     };
-    ghc821Binary = callPackage ../development/haskell-modules {
-      ghc = compiler.ghc821Binary;
+    ghc822 = callPackage ../development/haskell-modules {
+      buildHaskellPackages = bh.packages.ghc822;
+      ghc = bh.compiler.ghc822;
       compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-8.2.x.nix { };
     };
     ghc841 = callPackage ../development/haskell-modules {
-      ghc = compiler.ghc841;
+      buildHaskellPackages = bh.packages.ghc841;
+      ghc = bh.compiler.ghc841;
       compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-8.4.x.nix { };
     };
     ghcHEAD = callPackage ../development/haskell-modules {
-      ghc = compiler.ghcHEAD;
+      buildHaskellPackages = bh.packages.ghcHEAD;
+      ghc = bh.compiler.ghcHEAD;
       compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-head.nix { };
     };
-    # TODO Support for multiple variants here
-    ghcCross = callPackage ../development/haskell-modules {
-      ghc = compiler.ghcHEAD.crossCompiler;
-      compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-head.nix { };
-    };
-    ghcjs = callPackage ../development/haskell-modules {
-      ghc = compiler.ghcjs;
+    ghcjs = callPackage ../development/haskell-modules rec {
+      buildHaskellPackages = ghc.bootPkgs;
+      ghc = bh.compiler.ghcjs;
       compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-7.10.x.nix { };
       packageSetConfig = callPackage ../development/haskell-modules/configuration-ghcjs.nix { };
     };
-    ghcjsHEAD = callPackage ../development/haskell-modules {
-      ghc = compiler.ghcjsHEAD;
+    ghcjsHEAD = callPackage ../development/haskell-modules rec {
+      buildHaskellPackages = ghc.bootPkgs;
+      ghc = bh.compiler.ghcjsHEAD;
       compilerConfig = callPackage ../development/haskell-modules/configuration-ghc-8.0.x.nix { };
       packageSetConfig = callPackage ../development/haskell-modules/configuration-ghcjs.nix { };
     };
     ghcHaLVM240 = callPackage ../development/haskell-modules {
-      ghc = compiler.ghcHaLVM240;
+      buildHaskellPackages = bh.packages.ghcHaLVM240;
+      ghc = bh.compiler.ghcHaLVM240;
       compilerConfig = callPackage ../development/haskell-modules/configuration-halvm-2.4.0.nix { };
     };
 
     # The integer-simple attribute set contains package sets for all the GHC compilers
     # using integer-simple instead of integer-gmp.
-    integer-simple =
-      let integerSimpleGhcNames =
-            pkgs.lib.filter (name: ! builtins.elem name integerSimpleExcludes)
-                            (pkgs.lib.attrNames packages);
-      in pkgs.lib.genAttrs integerSimpleGhcNames (name: packages."${name}".override {
-       ghc = compiler.integer-simple."${name}";
-       overrides = _self : _super : {
-         integer-simple = null;
-         integer-gmp = null;
-       };
+    integer-simple = let
+      integerSimpleGhcNames = pkgs.lib.filter
+        (name: ! builtins.elem name integerSimpleExcludes)
+        (pkgs.lib.attrNames packages);
+    in pkgs.lib.genAttrs integerSimpleGhcNames (name: packages."${name}".override {
+      ghc = compiler.integer-simple."${name}";
+      overrides = _self : _super : {
+        integer-simple = null;
+        integer-gmp = null;
+      };
     });
 
   };

pkgs/top-level/release-cross.nix

···
   gnuCommon = lib.recursiveUpdate common {
     buildPackages.gcc = nativePlatforms;
     coreutils = nativePlatforms;
+    haskell.packages.ghcHEAD.hello = nativePlatforms;
+    haskell.packages.ghc822.hello = nativePlatforms;
   };
 
   linuxCommon = lib.recursiveUpdate gnuCommon {
···
     mpg123 = nativePlatforms;
   });
 
+  /* Linux on Aarch64 (TODO make android for real)  */
+  android = mapTestOnCross lib.systems.examples.aarch64-multiplatform (linuxCommon // {
+  });
 
   /* Cross-built bootstrap tools for every supported platform */
   bootstrapTools = let