Cannot debug Qt source

Starting with Qt 4.8.0, I am unable to reach breakpoints inside Qt source code, or step into Qt source code when using GDB (4.4.0, as in the Qt SDK 1.2.1)

I have tested multiple Qt versions by setting a breakpoint on a Qt source code line.
"works" means that I reach the breakpoint, and can further step into Qt sources
"doesn't work" mean that I reach a break in my source code, where the Qt method with the actual breakpoint is called.
4.7.3 on GDB: works
4.8.0 on GDB: doesn't work
4.8.1 on GDB: doesn't work
4.8.2 on GDB: doesn't work
4.8.0 on CDB: works