Try #628:

Author: iohk-bors[bot]

builder/comp-builder.nix

@@ -1,7 +1,7 @@
 { stdenv, buildPackages, ghc, lib, gobject-introspection ? null, haskellLib, makeConfigFiles, ghcForComponent, hsPkgs, runCommand, libffi, gmp, zlib, ncurses, nodejs }:
 
 lib.makeOverridable (
-let self = 
+let self =
 { componentId
 , component
 , package
@@ -34,7 +34,10 @@ let self =
 , dontStrip ? component.dontStrip
 
 , enableStatic ? component.enableStatic
-, enableShared ? component.enableShared && !haskellLib.isCrossHost
+, enableShared ? ghc.enableShared && component.enableShared && !haskellLib.isCrossHost
+               # on x86 we'll use shared libraries, even with musl m(
+               # ghc's internal linker seems to be broken on x86.
+               && !(stdenv.hostPlatform.isMusl && !stdenv.hostPlatform.isx86)
 , enableDeadCodeElimination ? component.enableDeadCodeElimination
 
 # Options for Haddock generation
@@ -52,8 +55,15 @@ let self =
 # Data
 , enableSeparateDataOutput ? component.enableSeparateDataOutput
 
+# Prelinked ghci libraries; will make iserv faster; especially for static builds.
+, enableLibraryForGhci ? true
+
 # Debug
 , enableDebugRTS ? false
+, enableDWARF ? false
+
+# LLVM
+, useLLVM ? ghc.useLLVM
 }@drvArgs:
 
 let
@@ -112,6 +122,7 @@ let
       (enableFeature enableExecutableProfiling "executable-profiling")
       (enableFeature enableStatic "static")
       (enableFeature enableShared "shared")
+      (enableFeature enableLibraryForGhci "library-for-ghci")
     ] ++ lib.optionals (stdenv.hostPlatform.isMusl && (haskellLib.isExecutableType componentId)) [
       # These flags will make sure the resulting executable is statically linked.
       # If it uses other libraries it may be necessary for to add more
@@ -120,9 +131,6 @@ let
       "--disable-executable-dynamic"
       "--ghc-option=-optl=-pthread"
       "--ghc-option=-optl=-static"
-      "--ghc-option=-optl=-L${gmp.override { withStatic = true; }}/lib"
-      "--ghc-option=-optl=-L${zlib.static}/lib"
-      "--ghc-option=-optl=-L${ncurses.override { enableStatic = true; }}/lib"
     ] ++ lib.optional enableSeparateDataOutput "--datadir=$data/share/${ghc.name}"
       ++ lib.optional doHaddock' "--docdir=${docdir "$doc"}"
       ++ lib.optional (enableLibraryProfiling || enableExecutableProfiling) "--profiling-detail=${profilingDetail}"
@@ -133,6 +141,10 @@ let
       ++ configureFlags
       ++ (ghc.extraConfigureFlags or [])
       ++ lib.optional enableDebugRTS "--ghc-option=-debug"
+      ++ lib.optional enableDWARF "--ghc-option=-g"
+      ++ lib.optionals useLLVM [
+        "--ghc-option=-fPIC" "--gcc-option=-fPIC"
+        ]
     );
 
   setupGhcOptions = lib.optional (package.ghcOptions != null) '' --ghc-options="${package.ghcOptions}"'';

compiler/ghc/default.nix

@@ -105,6 +105,11 @@ let
   '' + stdenv.lib.optionalString (!enableTerminfo) ''
     WITH_TERMINFO=NO
   ''
+  # musl doesn't have a system-linker. Only on x86, and on x86 we need it, as
+  # our elf linker for x86_64 is broken.
+  + stdenv.lib.optionalString (targetPlatform.isMusl && !targetPlatform.isx86) ''
+    compiler_CONFIGURE_OPTS += --flags=-dynamic-system-linker
+  ''
   # While split sections are now enabled by default in ghc 8.8 for windows,
   # the seem to lead to `too many sections` errors when building base for
   # profiling.
@@ -333,6 +338,7 @@ in let configured-src = stdenv.mkDerivation (rec {
 
     inherit llvmPackages;
     inherit enableShared;
+    inherit useLLVM;
 
     # Our Cabal compiler name
     haskellCompilerName = "ghc-${version}";