@RadicalEdward The problem of "implementation-defined" and "undefined" behaviours that are too numerous in C and C++: the compiler can do anything (ignoring the lines, launching a game, removing the files, formating the disks, etc.). Those should not exist in a programming language.
I'm not.
As long as the implemented behaviors are properly documented, undefined behaviours can be useful hooks: don't forget that C is a language designed to be used in a wide variety of use cases: portability is valuable in many of them, but sometimes is not relevant at all.