openexr: explictly use emulator to avoid having to set boot.binfmt.emulatedSystems

pkgs/development/libraries/openexr/default.nix

@@ -1,4 +1,9 @@
-{ lib, stdenv, fetchurl, autoconf, automake, libtool, pkgconfig, zlib, ilmbase }:
+{ lib, stdenv, buildPackages, fetchurl, autoconf, automake, libtool, pkgconfig, zlib, ilmbase, }:
+
+let
+  # Doesn't really do anything when not crosscompiling
+  emulator = stdenv.hostPlatform.emulator buildPackages;
+in
 
 stdenv.mkDerivation rec {
   name = "openexr-${version}";
@@ -15,6 +20,22 @@ stdenv.mkDerivation rec {
 
   outputs = [ "bin" "dev" "out" "doc" ];
 
+  # Needed because there are some generated sources. Solution: just run them under QEMU.
+  postPatch = ''
+    for file in b44ExpLogTable dwaLookups
+    do
+      # Ecape for both sh and Automake
+      emu=${lib.escapeShellArg (lib.replaceStrings ["$"] ["$$"] emulator)}
+      before="./$file > $file.h"
+      after="$emu $before"
+      substituteInPlace IlmImf/Makefile.am \
+        --replace "$before" "$after"
+    done
+
+    # Make sure the patch succeeded
+    [[ $(grep "$emu" IlmImf/Makefile.am | wc -l) = 2 ]]
+  '';
+
   preConfigure = ''
     patchShebangs ./bootstrap
     ./bootstrap