title: .h generated from .h.in?
body: <p>There are struct definitions in the .h file that my library creates after I build it.. but I cannot find these in the corresponding .h.in. Can somebody tell me how all this works and where it gets the extra info from? </p>
  
  <p>To be specific: I am building pth, the userspace threading library. It has pth_p.h.in, which doesn't contain the struct definition I am looking for, yet when I build the library, a pth_p.h appears and it has the definition I need. </p>
  
  <p>In fact, I have searched every single file in the library before it is built and cannot find where it is generating the struct definition.</p>