Re: [RFC-Discuss] Scalar Type Declarations v0.5

Christoph, On Wed, Feb 18, 2015 at 6:09 PM, Christoph Becker <cmbecker69@gmx.de> wrote: > Anthony Ferrara wrote: > >> 3. int typed variables can resolve a parameter type of float So >> calling requiresAFloat(10) will work even in strict mode. > > Have you considered the overflow behavior of ints resulting in a float? > For instance, the following code would produce E_RECOVERABLE_ERROR, AIUI: > > <?php > > declare(strict_types=1); > > function foo(int a, int b) { > bar(a * b); > } > > function bar(int n) { > } > > foo(10000000000, 10000000000); > > It seems to me that this behavior is hard to deal with generally for > programmers as well as static analyzers. Andreas' bigint RFC[1] would > solve that issue, but it has been withdrawn, and AFAIK nobody is working > on it. OTOH, bigint would make the widening from int to float > potentially even more lossy (i.e. inaccurate) than it is now (64bit ints > vs. IEEE 754 doubles). > > IIRC, Pascal does not promote int to float on overflow, but rather > discards the high bits (unless overflow checking is enabled; available > only in some "newer" dialects). I don't know how Java handles this > case, but I assume there's no promotion to float either. > > [1] <https://wiki.php.net/rfc/bigint> > That is a very good point. We had discussed that a while ago, but it hasn't come up in a while here. I've added a section in the RFC on it: https://wiki.php.net/rfc/scalar_type_hints_v5#integer_overflow_to_float_behavior Basically, I don't see any sane alternative but to have it cause an error at runtime. It's not precision loss, it's magnitude loss. The only other thing I can think of is to have the operators not promote in strict mode, but that's even worse since now you're clamping and not even giving the ability to detect it. I don't think in practice it will be a huge issue, but even if it comes up, it'll at least error sanely... Thanks Anthony