Proposed resolution:

This wording is relative to N5014.

1. Modify [optional.ref.observe] as indicated:

   template<class U = remove_cv_t<T>> constexpr remove_cv_t<T> value_or(U&& u) const;
   

   -?- Constraints: `T` is a non-array object type.

   -8- Let `X` be remove_cv_t<T>.

   -9- Mandates: is_constructible_v<X, T&> && is_convertible_v<U, X> is `true`.

   -10- Effects: Equivalent to:

   return has_value() ? *val : static_cast<X>(std::forward<U>(u));
   

   -?- Remarks: The return type is unspecified if `T` is an array type or a non-object type. [Note ?: This is to avoid the declaration being ill-formed. — end note]

[ Kona 2025-11-08; Status changed: Immediate → WP. ]

[ Kona 2025-11-03; approved by LWG. Status changed: New → Immediate. ]

[ 2025-10-16; Jonathan provides new wording ]

[ 2025-10-16; Reflector poll ]

Set priority to 1 after reflector poll.

Why not just add Constraints: and use decay_t<T> for the return type, instead of "not always present" which is currently only used for member types, not member functions.

Currently, if `T` is an array type or a function type, instantiation of std::optional<T&> is still ill-formed, because the return type of its `value_or` member function is specified as remove_cv_t<T>, which is invalid as a return type.

However, we don't exclude such T& from valid contained types. Given only `value_or` is problematic here, perhaps we can avoid providing it if `T` is not returnable.