Look at LLVM's doxygen, say, http://www.llvm.org/doxygen/classllvm_1_1MachineRegisterInfo.... You see how things like const, bool, and unsigned are all believed to be classes? Go further down, and you can find a definition of a global variable Reg, which is from a case where Doxygen managed to think that the arguments of a function a global variables.

That's just the stuff I have readily available; there's been several times where I tried to use Doxygen to figure something out, only to discover that it was horribly confused and worse than useless (since it looks like it can tell you the information, but it doesn't figure it out).