anchor.diff:  
     opal = callPackage ../development/libraries/opal {
       ffmpeg = ffmpeg_2;
  -    stdenv = overrideCC stdenv gcc6;
  +    stdenv = overrideCC stdenv buildPackages.gcc6;
     };
   
     openh264 = callPackage ../development/libraries/openh264 { };
  
positive.code:   yacc = bison; # TODO: move to aliases.nix
  
    blackmagic = callPackage ../development/tools/misc/blackmagic {
      stdenv = overrideCC stdenv gcc6;
      gcc-arm-embedded = pkgsCross.arm-embedded.buildPackages.gcc;
      binutils-arm-embedded = pkgsCross.arm-embedded.buildPackages.binutils;
    };
  
negative.code: 
    avian = callPackage ../development/compilers/avian {
      inherit (darwin.apple_sdk.frameworks) CoreServices Foundation;
      stdenv = if stdenv.cc.isGNU then overrideCC stdenv buildPackages.gcc49 else stdenv;
    };
  
    bigloo = callPackage ../development/compilers/bigloo { };
  