Debugging C++ templates is difficult. Debugging C++ templates with GDB can be an act of torture for even seasoned GDB users. I like GDB, but there are some tricks you should know when using it to debug templates. In this post, I deal with setting breakpoints.
Breakpoint Basics:
Setting a breakpoint in GDB is supposed to be simple. Here we set a breakpoint at line 50 in file main.cpp:
(gdb) b main.cpp:50
Breakpoint 1 at 0×804937a: file main.cpp, line 50.
We can also use the function name and GDB will attempt to find the correct location for us:
(gdb) b DoSomething
Breakpoint 2 at 0×8049334: file main.cpp, line 150
Simple, right? Just wait…
Breakpoint Gotchas:
GDB’s breakpoint logic is pretty handy for simple projects, but it can break down fast when things get more complicated.
For example, let’s say your application is plugin-driven, with each plugin being a separate library. Now assume each plugin has a Plugin.cpp file under it’s own Source directory. Try to set a breakpoint in the Initialize() method of the Plugin class:
(gdb) b Initialize
Breakpoint 3 at 0×8049717: file main.cpp, line 230
Oops! There is an Initialize() method in main.cpp and GDB thought that’s where we wanted to put it: wrong!
