https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92675
--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #3)
> -1u also works
Not in a template:
#include <type_traits>
template<typename U>
constexpr std::enable_if_t<std::is_unsigned<U>::value, bool>
is_max(U u)
{
#ifdef GOOD
U max = -1; // good
#else
U max = -1u; // bad
#endif
return u == max;
}
static_assert(is_max(-1ull));
This fails when GOOD isn't defined, because -1u is UINT_MAX not the maximum
value for the type.
You can use std::numeric_limits<U>::max() or U(-1) but -1 is a convenient
shorthand that does the right thing.
