Rather than look at it as "does not happen" it may be helpful to think of "if this does happen anything is correct". So you can then split the codepaths into pa

Rather than look at it as "does not happen" it may be helpful to think of "if this does happen anything is correct". So you can then split the codepaths into parts where the compiler is strictly specified in what it has to do (defined behaviour) and parts where anything is "correct". Of course the most optimal solution is to just produce the best code you can for the first category, because what code also happens to be "correct" for the second category. Of course this is equivalent to "does not happen" but may make more sense as to why the compiler acts this way.