anchor.diff:  
     ycmd = callPackage ../development/tools/misc/ycmd {
       inherit (darwin.apple_sdk.frameworks) Cocoa;
  -    llvmPackages = llvmPackages_5;
       python = python2;
     };
   
  
positive.code:   llvm_35 = llvmPackages_35.llvm;
    llvm_34 = llvmPackages_34.llvm;
  
    llvmPackages = recurseIntoAttrs llvmPackages_4;
  
    llvmPackagesSelf = llvmPackages_34.override {
      stdenv = libcxxStdenv;
  
negative.code:     inherit (stdenvAdapters) overrideCC;
    };
  
    llvmPackages_4 = callPackage ../development/compilers/llvm/4 {
      inherit (stdenvAdapters) overrideCC;
    };
  
    llvmPackages_5 = callPackage ../development/compilers/llvm/5 ({
      inherit (stdenvAdapters) overrideCC;
    } // stdenv.lib.optionalAttrs stdenv.isDarwin {
      cmake = cmake.override { isBootstrap = true; };
      libxml2 = libxml2.override { pythonSupport = false; };
      python2 = callPackage ../development/interpreters/python/cpython/2.7/boot.nix { inherit (darwin) CF configd; };
    });
  
    manticore = callPackage ../development/compilers/manticore { };
  
  