patch GHC 7.8.4 on darwin to fix template haskell + hpc

pkgs/development/compilers/ghc/7.8.4.nix

@@ -1,6 +1,6 @@
 { stdenv, fetchurl, ghc, perl, gmp, ncurses, libiconv }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation (rec {
   version = "7.8.4";
   name = "ghc-${version}";
 
@@ -45,4 +45,7 @@ stdenv.mkDerivation rec {
     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/hpc-7.8.4.patch

@@ -0,0 +1,13 @@
+diff --git a/compiler/cmm/CLabel.hs b/compiler/cmm/CLabel.hs
+index 991fc57..0aad221 100644
+--- a/compiler/cmm/CLabel.hs
++++ b/compiler/cmm/CLabel.hs
+@@ -877,7 +877,7 @@ labelDynamic dflags this_pkg this_mod lbl =
+ 
+    PlainModuleInitLabel m -> not (gopt Opt_Static dflags) && this_pkg /= (modulePackageId m)
+ 
+-   HpcTicksLabel m        -> not (gopt Opt_Static dflags) && this_pkg /= (modulePackageId m)
++   HpcTicksLabel m        -> not (gopt Opt_Static dflags) && this_mod /= m
+ 
+    -- Note that DynamicLinkerLabels do NOT require dynamic linking themselves.
+    _                 -> False