< cpp‎ | concepts
Defined in header <concepts>
template< class T, class U >

concept common_reference_with =
    std::same_as<std::common_reference_t<T, U>, std::common_reference_t<U, T>> &&
    std::convertible_to<T, std::common_reference_t<T, U>> &&

    std::convertible_to<U, std::common_reference_t<T, U>>;
(since C++20)

The concept common_reference_with<T, U> specifies that two types T and U share a common reference type (as computed by std::common_reference_t) to which both can be converted.

[edit] Semantic requirements

T and U model std::common_reference_with<T, U> only if, given equality-preserving expressions t1, t2, u1 and u2 such that decltype((t1)) and decltype((t2)) are both T and decltype((u1)) and decltype((u2)) are both U,

In other words, the conversion to the common reference type must preserve equality.

[edit] See also

determines the common reference type of a group of types
(class template) [edit]
specifies that two types share a common type
(concept) [edit]
determines the common type of a group of types
(class template) [edit]