anchor.diff:  { stdenv, fetchurl, cmake, ninja, llvm_5, llvm_8, curl, tzdata
   , python, libconfig, lit, gdb, unzip, darwin, bash
  -, callPackage, makeWrapper, targetPackages
  +, callPackage, makeWrapper, runCommand, targetPackages
   , bootstrapVersion ? false
   , version ? "1.17.0"
   , ldcSha256 ? "1aag5jfrng6p4ms0fs90hjbv9bcj3hj8h52r68c3cm6racdajbva"
  
positive.code:   buildInputs = [ curl tzdata ];
  
    cmakeFlags = stdenv.lib.optionals (!bootstrapVersion) [
      "-DD_FLAGS=-d-version=TZDatabaseDir;-d-version=LibcurlPath;-J$PWD"
      "-DCMAKE_BUILD_TYPE=Release"
    ];
  
  
negative.code:       rm ldc-${version}-src/tests/d2/dmd-testsuite/fail_compilation/mixin_gc.d
        rm ldc-${version}-src/tests/d2/dmd-testsuite/runnable/xtest46_gc.d
        rm ldc-${version}-src/tests/d2/dmd-testsuite/runnable/testptrref_gc.d
  
        # test depends on current year
        rm ldc-${version}-src/tests/d2/dmd-testsuite/compilable/ddocYear.d
    ''
  
    + stdenv.lib.optionalString (!bootstrapVersion && stdenv.hostPlatform.isDarwin) ''
        # https://github.com/NixOS/nixpkgs/issues/34817
        rm -r ldc-${version}-src/tests/plugins/addFuncEntryCall
    '';
  
    postPatch = ''
  