enable split-output builds for all haskellPackages

pkgs/development/haskell-modules/configuration-common.nix

@@ -728,7 +728,7 @@ self: super: {
       };
     in overrideCabal super.servant (old: {
       postInstall = old.postInstall or "" + ''
-        ln -s ${docs} $out/share/doc/servant
+        ln -s ${docs} $doc/share/doc/servant
       '';
     });
 

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

@@ -1,5 +1,5 @@
 { stdenv, fetchurl, ghc, pkgconfig, glibcLocales, coreutils, gnugrep, gnused
-, jailbreak-cabal, hscolour, cpphs, nodejs, lib
+, jailbreak-cabal, hscolour, cpphs, nodejs, lib, removeReferencesTo
 }: let isCross = (ghc.cross or null) != null; in
 
 { pname
@@ -53,6 +53,8 @@
 , coreSetup ? false # Use only core packages to build Setup.hs.
 , useCpphs ? false
 , hardeningDisable ? lib.optional (ghc.isHaLVM or false) "all"
+, enableSeparateDataOutput ? false
+, enableSeparateDocOutput ? doHaddock
 } @ args:
 
 assert editedCabalFile != null -> revision != null;
@@ -108,6 +110,8 @@ let
 
   defaultConfigureFlags = [
     "--verbose" "--prefix=$out" "--libdir=\\$prefix/lib/\\$compiler" "--libsubdir=\\$pkgid"
+    (optionalString enableSeparateDataOutput "--datadir=$data/share/${ghc.name}")
+    (optionalString enableSeparateDocOutput "--docdir=$doc/share/doc")
     "--with-gcc=$CC" # Clang won't work without that extra information.
     "--package-db=$packageConfDir"
     (optionalString (enableSharedExecutables && stdenv.isLinux) "--ghc-option=-optl=-Wl,-rpath=$out/lib/${ghc.name}/${pname}-${version}")
@@ -144,7 +148,7 @@ let
   allPkgconfigDepends = pkgconfigDepends ++ libraryPkgconfigDepends ++ executablePkgconfigDepends ++
                         optionals doCheck testPkgconfigDepends ++ optionals withBenchmarkDepends benchmarkPkgconfigDepends;
 
-  nativeBuildInputs = buildTools ++ libraryToolDepends ++ executableToolDepends;
+  nativeBuildInputs = buildTools ++ libraryToolDepends ++ executableToolDepends ++ [ removeReferencesTo ];
   propagatedBuildInputs = buildDepends ++ libraryHaskellDepends ++ executableHaskellDepends;
   otherBuildInputs = setupHaskellDepends ++ extraLibraries ++ librarySystemDepends ++ executableSystemDepends ++
                      optionals (allPkgconfigDepends != []) ([pkgconfig] ++ allPkgconfigDepends) ++
@@ -173,6 +177,9 @@ assert allPkgconfigDepends != [] -> pkgconfig != null;
 stdenv.mkDerivation ({
   name = "${pname}-${version}";
 
+  outputs = if (args ? outputs) then args.outputs else ([ "out" ] ++ (optional enableSeparateDataOutput "data") ++ (optional enableSeparateDocOutput "doc"));
+  setOutputFlags = false;
+
   pos = builtins.unsafeGetAttrPos "pname" args;
 
   prePhases = ["setupCompilerEnvironmentPhase"];
@@ -323,6 +330,14 @@ stdenv.mkDerivation ({
       done
     ''}
 
+    ${optionalString enableSeparateDocOutput ''
+    for x in $doc/share/doc/html/src/*.html; do
+      remove-references-to -t $out $x
+    done
+    mkdir -p $doc
+    ''}
+    ${optionalString enableSeparateDataOutput "mkdir -p $data"}
+
     runHook postInstall
   '';
 

pkgs/development/haskell-modules/lib.nix

@@ -111,4 +111,6 @@ rec {
   overrideSrc = drv: { src, version ? drv.version }:
     overrideCabal drv (_: { inherit src version; editedCabalFile = null; });
 
+  hasNoDataOutput = drv: overrideCabal drv (drv: { hasDataDir = false; });
+  hasNoDocOutput = drv: overrideCabal drv (drv: { hasDocDir = false; });
 }