On Wed, Nov 02, 2022 at 12:52:32PM +0100, Rasmus Villemoes wrote: > On 24/10/2022 22.11, Gwan-gyeong Mun wrote: > > From: Kees Cook <keescook@xxxxxxxxxxxx> > > > > Implement a robust overflows_type() macro to test if a variable or > > constant value would overflow another variable or type. This can be > > used as a constant expression for static_assert() (which requires a > > constant expression[1][2]) when used on constant values. This must be > > constructed manually, since __builtin_add_overflow() does not produce > > a constant expression[3]. > > > > Additionally adds castable_to_type(), similar to __same_type(), but for > > checking if a constant value would overflow if cast to a given type. > > > > > +#define __overflows_type_constexpr(x, T) ( \ > > + is_unsigned_type(typeof(x)) ? \ > > + (x) > type_max(typeof(T)) ? 1 : 0 \ > > + : is_unsigned_type(typeof(T)) ? \ > > + (x) < 0 || (x) > type_max(typeof(T)) ? 1 : 0 \ > > + : (x) < type_min(typeof(T)) || \ > > + (x) > type_max(typeof(T)) ? 1 : 0) > > + > > Can't all these instances of "foo ? 1 : 0" be simplified to "foo"? That > would improve the readability of this thing somewhat IMO. Oh, good point. :P I'll fix these. -- Kees Cook
