On Mon, Apr 22, 2013 at 4:44 AM, Warlich, Christof <christof.warlich@xxxxxxxxxxx> wrote: > > Well, it should at least give consistent values regardless of > the level of optimization being used. Well, it's undefined, so there is no promise of consistency. The compiler provides a contract for how it compiles programs, and that contract is written out in the language standard. The language standard says this case is undefined, so that is what you get: unpredictable and undocumented behaviour. What you are implicitly suggesting is that GCC should provide a different contract. But you'll find that your suggestion would slow down all cases of float to int conversion, so some people will not want GCC to implement it. In any case the way to change the contract is not to convince the GCC developers; it's to convince the language standards bodies, as they in principle represent all users of the language. They can decide the right tradeoff between slower execution and undefined behaviour. Note that historically C/C++ always choose undefined behaviour over slower execution. Ian
