Losing the magic

Losing the magic

Yep - and the O_PONIES problem, when you reduce it to its core is simple. The standard permits non-deterministic behaviour (some behaviours are defined as "each execution of the program must exhibit one behaviour from the allowed list of behaviours", not as a single definite behaviour). The standard also permits implementation-defined behaviour - where the standard doesn't define how a construct behaves, but instead says "your implementation will document how it interprets this construct".

What the O_PONIES crowd want is to convert "annoying" UB in C and C++ to implementation-defined behaviour. There's a process for doing that - it involves going through the standards committees writing papers and convincing people that this is the right thing to do. The trouble is that this is hard work - as John Regehr has already demonstrated by making the attempt - since UB has been used by the standards committee as a way of avoiding difficult discussions about what is, and is not, acceptable in a standards-compliant compiler, and thus re-opening the discussion is going to force people to confront those arguments all over again.