It's not really the output of an external command etc. I need. It's the STDERR of a C library which an XS module uses. So when I make certain sub calls, it gets into the C routines and it's their STDERR I want to capture. It all works fine on non-Windows using STDERR redirection to a file or Capture::Tiny but on Windows, the STDERR of the library refuses to be captured. This seems to be a windows specific thing - I read somewhere that re-opening STDERR on windows de-couples perl STDERR from the C library STDERR. If so, I'm really in the dark as to how to capture this.
I don't think I understand how to do that in my case. I am in the middle of a large program and need to make some sub calls to some XS/external lib subs. There isn't anything I can really launch as an external processs here. Am I missing something? I know it'll always work if I redirect everything before I start but my problem is that I am already deep in some code at the point where I need to run some XS subs and get their STDERR.