Ada overflow semantics are precisely what programmers assumed were C overflow semantics on architectures that roll-over on signed arithmetic (e.g. basically every processor architetcure in current wide use). The original intent of the C "undefined behavior" category, as far as I can tell, was to in this case permit compilers on dissenting architectures to make another choice. For example, on the Itanium you might want to have a trap on overflow. Because C is comfortable with "it works differently on different processors". So it is my intention to repair the obscurity in the language by spelling out what I am 100% sure would have been obvious to C programmers and language developers at on time.