A fun one that'd fit list be sequence point violations like
i = i++
Fun, sure, but also GCC and Clang will both warn with -Wall (-Wsequence-point / -Wunsequenced).
This would also be a code smell even if it was well defined.
Only in C, that one is defined in C++.
edit: I'm not sure it's even undefined in C.
Fun, sure, but also GCC and Clang will both warn with -Wall (-Wsequence-point / -Wunsequenced).