"cscope" type functionality

[Perry Smith]

gcc/g++ has the -M options to help in creating Makefiles.  It struck  
me this morning that a similar switch to help in the creation of a  
database to use to create a "cscope" type facility would be very  
nice.  It would be nice if both cpp and gcc/g++ had this ability.

Has/Does anything like this already exist?  -- perhaps hidden in one  
if the debugging files that can be produced?

Thank you,
Perry Smith