anchor.diff:  
       fixDarwinDylibNames $(find "$(pwd)/lib" -name "*.dylib")
       export DYLD_LIBRARY_PATH=$(pwd)/lib
  -  ''
  -  else
  -    "";
  +  '';
   
     # https://github.com/ldc-developers/ldc/issues/2497#issuecomment-459633746
  -  additionalExceptions = if stdenv.hostPlatform.isDarwin then
  -    "|druntime-test-shared"
  -  else
  -    "";
  +  additionalExceptions = stdenv.lib.optionalString stdenv.hostPlatform.isDarwin
  +    "|druntime-test-shared";
   
     doCheck = !bootstrapVersion;
   
  
positive.code: 
    makeFlags = [ "DMD=$DMD" ];
  
    fixNames = if stdenv.hostPlatform.isDarwin then ''
      fixDarwinDylibNames() {
        local flags=()
  
  
negative.code:   '';
  
    nativeBuildInputs = [ cmake ninja makeWrapper unzip ]
      ++ stdenv.lib.optionals (!bootstrapVersion) [
        bootstrapLdc python lit
      ]
      ++ stdenv.lib.optional (!bootstrapVersion && stdenv.hostPlatform.isDarwin)
        # https://github.com/NixOS/nixpkgs/issues/57120
        # https://github.com/NixOS/nixpkgs/pull/59197#issuecomment-481972515
        llvm_5
      ++ stdenv.lib.optional (!bootstrapVersion && !stdenv.hostPlatform.isDarwin)
        llvm_8
      ++ stdenv.lib.optional (!bootstrapVersion && !stdenv.hostPlatform.isDarwin)
        # https://github.com/NixOS/nixpkgs/pull/36378#issuecomment-385034818
        gdb
      ++ stdenv.lib.optionals (bootstrapVersion) [
        libconfig llvm_5
      ]
      ++ stdenv.lib.optional stdenv.hostPlatform.isDarwin
        darwin.apple_sdk.frameworks.Foundation;
  
  
    buildInputs = [ curl tzdata ];
  
    cmakeFlags = stdenv.lib.optionals (!bootstrapVersion) [
      "-DD_FLAGS=-d-version=TZDatabaseDir;-d-version=LibcurlPath;-J$PWD"
      "-DCMAKE_BUILD_TYPE=Release"
    ];
  
    postConfigure = ''
      export DMD=$PWD/bin/ldmd2
  