+2  A: 

Hello, try

break mymethod

As the function name in not ambiguous, it should work.

See. http://www.unknownroad.com/rtfm/gdbtut/gdbbreak.html#BCPPFUNC

Regards, Valentin Heinitz

Valentin Heinitz
A: 

If mymethod is a member of myclass:

break myclass::mymethod

There should be no need to specify the file.

Clifford