Been there, found undefined behavior where there should not be any. Imagine a function that takes a bool param with the following code, but neither branch gets executed:

if (b)
   doStuffForTrue();
if (!b)
   doStuffForFalse();

In a function that is passed an uninitialized bool parameter, in gcc compiler, both branches can get executed even when b is const. Reason: uninitialized bool in gcc can have values of a random integer, and while if(b) {} else ({} is guaranteed to execute only one branch, bool evaluations of a bool value take a “shortcut” that only has defined behavior with an initialized bool.

Same code with an uninitialized integer works as expected, btw.