Make the number of stack overflows more visible to users.
@mpickering recently worked on an issue where a small change caused because it moved stack useage into the "twilight zone" where we continuously under and overflowed the stack by repeated stack expansion and contraction. Even if the absolute amount of stack space used is relatively small.
Currently it's quite hard to diagnose this without deep knowledge of the RTS. It might be interesting the expose a stack overflow counter in some place more visible like in the +RTS -s
output.