Resurrect the old ghcWithPackages wrapper under the attribute name 'ghcWithPackagesOld'.

pkgs/development/compilers/ghc/with-packages-old.nix

@@ -0,0 +1,127 @@
+{stdenv, ghc, packages ? [], makeWrapper}:
+
+stdenv.mkDerivation rec {
+  name = "haskell-env-${ghc.name}";
+
+  allPackages = stdenv.lib.filter (x: x ? pname) (stdenv.lib.closePropagation packages);
+  buildInputs = allPackages ++ [makeWrapper];
+  propagatedBuildInputs = packages;
+
+  unpackPhase = "true";
+
+  installPhase = ''
+    numversion=$(${ghc}/bin/ghc --numeric-version)
+    majorversion=''${numversion%%.*}
+    minorversion=''${numversion#*.}
+    minorversion=''${minorversion%%.*}
+
+    if [[ $majorversion -gt 6 ]] && [[ $minorversion -gt 4 ]]; then
+      globalConf="--global-package-db"
+    else
+      globalConf="--global-conf"
+    fi
+
+    originalTopDir="${ghc}/lib/ghc-${ghc.version}"
+    originalPkgDir="$originalTopDir/package.conf.d"
+    linkedTopDir="$out/lib/ghc-${ghc.version}"
+    linkedPkgDir="$linkedTopDir/package.conf.d"
+
+    mkdir -p $out/bin
+    mkdir -p $linkedTopDir
+    mkdir -p $linkedPkgDir
+
+    echo "Linking GHC core libraries:"
+
+    echo -n "Linking $originalTopDir "
+    for f in "$originalTopDir/"*; do
+      if test -f $f; then
+        ln -s $f $linkedTopDir
+        echo -n .
+      fi
+    done
+    echo
+
+    echo -n "Linking $originalPkgDir "
+    for f in "$originalPkgDir/"*.conf; do
+      ln -s $f $linkedPkgDir
+      echo -n .
+    done
+    echo
+
+    echo "Linking selected packages and dependencies:"
+
+    for currentPath in ${stdenv.lib.concatStringsSep " " allPackages}; do
+      currentPkgDir="$currentPath/lib/ghc-${ghc.version}"
+      # Check if current path is a Cabal package for the current GHC
+      if test -d $currentPkgDir; then
+        echo -n "Linking $currentPath "
+        for f in "$currentPath/bin/"*; do
+          ln -s $f $out/bin
+          echo -n .
+        done
+        for f in "$currentPath/etc/bash_completion.d/"*; do
+          mkdir -p $out/etc/bash_completion.d
+          ln -s $f $out/etc/bash_completion.d/
+          echo -n .
+        done
+        for s in 1 2 3 4 5 6 7 8 9; do
+          for f in "$currentPath/share/man/man$s/"*; do
+            mkdir -p $out/share/man/man$s
+            ln -sv $f $out/share/man/man$s/
+            echo -n .
+          done
+        done
+        for f in "$currentPath/share/emacs/site-lisp/"*; do
+          mkdir -p $out/share/emacs/site-lisp
+          ln -s $f $out/share/emacs/site-lisp/
+          echo -n .
+        done
+        for f in "$currentPath/share/ghci/"*; do
+          mkdir -p $out/share/ghci
+          ln -s $f $out/share/ghci/
+          echo -n .
+        done
+        for f in "$currentPkgDir/package.conf.d/"*.conf; do
+          ln -s $f $linkedPkgDir
+          echo -n .
+        done
+        echo
+      fi
+    done
+
+    echo -n "Generating package cache "
+    ${ghc}/bin/ghc-pkg $globalConf $linkedPkgDir recache
+    echo .
+
+    echo -n "Generating wrappers "
+
+    for prg in ghc ghci ghc-${ghc.version} ghci-${ghc.version}; do
+      # The NIX env-vars are picked up by our patched version of ghc-paths.
+      makeWrapper ${ghc}/bin/$prg $out/bin/$prg \
+        --add-flags "-B$linkedTopDir" \
+        --set "NIX_GHC"        "$out/bin/ghc"     \
+        --set "NIX_GHCPKG"     "$out/bin/ghc-pkg" \
+        --set "NIX_GHC_LIBDIR" "$linkedTopDir"
+      echo -n .
+    done
+
+    for prg in runghc runhaskell; do
+      makeWrapper ${ghc}/bin/$prg $out/bin/$prg --add-flags "-f $out/bin/ghc"
+      echo -n .
+    done
+
+    for prg in ghc-pkg ghc-pkg-${ghc.version}; do
+      makeWrapper ${ghc}/bin/$prg $out/bin/$prg --add-flags "$globalConf $linkedPkgDir"
+      echo -n .
+    done
+
+    for prg in hp2ps hpc hasktags hsc2hs haddock haddock-${ghc.version}; do
+      if test -x ${ghc}/bin/$prg -a ! -x $out/bin/$prg; then
+        ln -s ${ghc}/bin/$prg $out/bin/$prg && echo -n .
+      fi
+    done
+    echo
+  '';
+
+  meta = ghc.meta;
+}

pkgs/top-level/haskell-packages.nix

@@ -106,6 +106,11 @@ let result = let callPackage = x : y : modifyPrio (newScope result.finalReturn x
     packages = pkgs self;
   };
 
+  ghcWithPackagesOld = pkgs : callPackage ../development/compilers/ghc/with-packages-old.nix {
+    ghc = ghc; # refers to ghcPlain
+    packages = pkgs self;
+  };
+
   # This is the Cabal builder, the function we use to build most Haskell
   # packages. It isn't the Cabal library, which is spelled "Cabal".