Created on 2019-09-27.00:00:00, last changed 2019-10-09.18:10:13.
This wording is relative to N4830.
Modify [iterator.range] as indicated:
template<class C> constexpr auto ssize(const C& c) -> common_type_t<ptrdiff_t, make_signed_t<decltype(c.size())>>;
-18- Returns:static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(c.size())>>>(c.size())
The overload of ssize specified in [iterator.range]/18 has no constraints, yet it specializes make_signed_t which has a precondition that its type parameter is an integral type or enumeration but not bool ([meta.trans.sign]). This precondition needs to be propagated to ssize as "Mandates [or Constraints]: decltype(c.size()) [meets the requirements for the type argument to make_signed]". "Mandates" seems to be more in line with LWG guidance since there are no traits nor concepts that observe ssize.
|2019-10-09 18:10:13||admin||set||messages: + msg10690|