anchor.diff:  { lib, stdenv, fetchFromGitHub, cmake, curl, openssl, s2n-tls, zlib
  +, aws-crt-cpp
   , aws-c-cal, aws-c-common, aws-c-event-stream, aws-c-io, aws-checksums
   , CoreAudio, AudioToolbox
   , # Allow building a limited set of APIs, e.g. ["s3" "ec2"].
  
positive.code: 
  stdenv.mkDerivation rec {
    pname = "aws-sdk-cpp";
    version = "1.8.130";
  
    src = fetchFromGitHub {
      owner = "awslabs";
      repo = "aws-sdk-cpp";
      rev = version;
      sha256 = "sha256-5T4l0KYB0utFTdEOtYT9trQ/JehQbXxk/IhI6YavErs=";
    };
  
    # FIXME: might be nice to put different APIs in different outputs
    # (e.g. libaws-cpp-sdk-s3.so in output "s3").
  
negative.code:   nativeBuildInputs = [ cmake curl ];
  
    buildInputs = [
      aws-crt-cpp
      curl openssl zlib
    ] ++ lib.optionals (stdenv.isDarwin &&
                          ((builtins.elem "text-to-speech" apis) ||
  