> Static analysis wouldn't have help me in my case, since I know that I can
> get Not_found in 10 different places.
> 
> Of cource, I could catch each of these at their location, and raise a
> specific exception for each.
> 
> This, however, would mess up the code.
> 
> /mattias

In those 10 places add 2 lines:

try ...
with Not_found -> assert false

where ... is the old code.

You will obtain exactly the behaviour you want: the file and line will
be reported by the runtime system.

(Joking) Furthermore, your boss will be proud of you since the program will be
10 lines longer (Joking).

Best regards,

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://cristal.inria.fr/~weis/