After loading the file, I started a dribble file as follows:

  M-x open-dribble-file RET /tmp/c-mode-debug.dribble RET

I then started editing the file until I encountered the syntax problem.
Near the end of the dribble file, after I encounter the problem, I end
up messing around a bit with turning on the echoing of syntactic
information, and it takes a while for me to get it right.  Please be
warned, that my exiting emacs afterward is contained within the dribble
file, so you may want to remove those characters before replaying it.

Here is the dribble file in question: