Child Process: Separate stdout from stderr

When running a ChildProcess, you choose whether to capture stderr and/or stdout. Once the process has finished, you can use readAllProcessOutput to get the output, but unless I’m missing something you don’t know what is stderr and what is stdout. It would be good to have a function that returns a little struct containing separate stdout and stderr instead of just a string.

I would love an API like:

struct ProcessOutput
  std::string stdout;
  std::string stderr;
  int exitCode;