You can set a breakpoint in a function, without having to locate the source for the function. You can do this from any source line that contains a call to the function.
See also:
Setting a breakpoint at the start of a function
Setting a breakpoint at the entry point to a function
Setting a breakpoint in an inlined function
Setting a breakpoint in a C++ template
Setting a breakpoint at the start of a member function in a C++ class
Setting a breakpoint at the location of a Call Stack entry
Setting breakpoints on functions from the Function/Label list.