Message 9063 - WG21 LWG Issues
Date
2017-03-03.22:08:49
Message id
9063

Content

Proposed resolution:

This wording is relative to N4640.

  1. Modify [optional.syn], header <optional> synopsis, as indicated:

    […]

// [optional.relops], relational operators
template <class T, class U>
constexpr bool operator==(const optional<T>&, const optional<TU>&);
template <class T, class U>
constexpr bool operator!=(const optional<T>&, const optional<TU>&);
template <class T, class U>
constexpr bool operator<(const optional<T>&, const optional<TU>&);
template <class T, class U>
constexpr bool operator>(const optional<T>&, const optional<TU>&);
template <class T, class U>
constexpr bool operator<=(const optional<T>&, const optional<TU>&);
template <class T, class U>
constexpr bool operator>=(const optional<T>&, const optional<TU>&);

[…]

// [optional.comp_with_t], comparison with T
template <class T, class U> constexpr bool operator==(const optional<T>&, const TU&);
template <class T, class U> constexpr bool operator==(const TU&, const optional<T>&);
template <class T, class U> constexpr bool operator!=(const optional<T>&, const TU&);
template <class T, class U> constexpr bool operator!=(const TU&, const optional<T>&);
template <class T, class U> constexpr bool operator<(const optional<T>&, const TU&);
template <class T, class U> constexpr bool operator<(const TU&, const optional<T>&);
template <class T, class U> constexpr bool operator<=(const optional<T>&, const TU&);
template <class T, class U> constexpr bool operator<=(const TU&, const optional<T>&);
template <class T, class U> constexpr bool operator>(const optional<T>&, const TU&);
template <class T, class U> constexpr bool operator>(const TU&, const optional<T>&);
template <class T, class U> constexpr bool operator>=(const optional<T>&, const TU&);
template <class T, class U> constexpr bool operator>=(const TU&, const optional<T>&);

  2. Modify [optional.relops] as indicated:

    template <class T, class U> constexpr bool operator==(const optional<T>& x, const optional<TU>& y);

    […] 

    template <class T, class U> constexpr bool operator!=(const optional<T>& x, const optional<TU>& y);

    […] 

    template <class T, class U> constexpr bool operator<(const optional<T>& x, const optional<TU>& y);

    […] 

    template <class T, class U> constexpr bool operator>(const optional<T>& x, const optional<TU>& y);

    […] 

    template <class T, class U> constexpr bool operator<=(const optional<T>& x, const optional<TU>& y);

    […] 

    template <class T, class U> constexpr bool operator>=(const optional<T>& x, const optional<TU>& y);

    […]

  3. Modify [optional.comp_with_t] as indicated:

    template <class T, class U> constexpr bool operator==(const optional<T>& x, const TU& v);

    -?- Requires: The expression *x == v shall be well-formed and its result shall be convertible to bool. [Note: T need not be EqualityComparable. — end note]

    -1- Effects: Equivalent to: return bool(x) ? *x == v : false; 

    template <class T, class U> constexpr bool operator==(const TU& v, const optional<T>& x);

    -?- Requires: The expression v == *x shall be well-formed and its result shall be convertible to bool.

    -2- Effects: Equivalent to: return bool(x) ? v == *x : false; 

    template <class T, class U> constexpr bool operator!=(const optional<T>& x, const TU& v);

    -?- Requires: The expression *x != v shall be well-formed and its result shall be convertible to bool.

    -3- Effects: Equivalent to: return bool(x) ? *x != v : true; 

    template <class T, class U> constexpr bool operator!=(const TU& v, const optional<T>& x);

    -?- Requires: The expression v != *x shall be well-formed and its result shall be convertible to bool.

    -4- Effects: Equivalent to: return bool(x) ? v != *x : true; 

    template <class T, class U> constexpr bool operator<(const optional<T>& x, const TU& v);

    -?- Requires: The expression *x < v shall be well-formed and its result shall be convertible to bool.

    -5- Effects: Equivalent to: return bool(x) ? *x < v : true; 

    template <class T, class U> constexpr bool operator<(const TU& v, const optional<T>& x);

    -?- Requires: The expression v < *x shall be well-formed and its result shall be convertible to bool.

    -6- Effects: Equivalent to: return bool(x) ? v < *x : false; 

    template <class T, class U> constexpr bool operator<=(const optional<T>& x, const TU& v);

    -?- Requires: The expression *x <= v shall be well-formed and its result shall be convertible to bool.

    -7- Effects: Equivalent to: return bool(x) ? *x <= v : true; 

    template <class T, class U> constexpr bool operator<=(const TU& v, const optional<T>& x);

    -?- Requires: The expression v <= *x shall be well-formed and its result shall be convertible to bool.

    -8- Effects: Equivalent to: return bool(x) ? v <= *x : false; 

    template <class T, class U> constexpr bool operator>(const optional<T>& x, const TU& v);

    -?- Requires: The expression *x > v shall be well-formed and its result shall be convertible to bool.

    -9- Effects: Equivalent to: return bool(x) ? *x > v : false; 

    template <class T, class U> constexpr bool operator>(const TU& v, const optional<T>& x);

    -?- Requires: The expression v > *x shall be well-formed and its result shall be convertible to bool.

    -10- Effects: Equivalent to: return bool(x) ? v > *x : true; 

    template <class T, class U> constexpr bool operator>=(const optional<T>& x, const TU& v);

    -?- Requires: The expression *x >= v shall be well-formed and its result shall be convertible to bool.

    -11- Effects: Equivalent to: return bool(x) ? *x >= v : false; 

    template <class T, class U> constexpr bool operator>=(const TU& v, const optional<T>& x);

    -?- Requires: The expression v >= *x shall be well-formed and its result shall be convertible to bool.

    -12- Effects: Equivalent to: return bool(x) ? v >= *x : true; 

    

    

    4.