View source for cpp/concepts/common with

===Semantic requirements===
T and U model {{co|std::common_with<T, U>}} only if, given [[cpp/concepts#Equality preservation|equality-preserving]] expressions {{tt|t1}}, {{tt|t2}}, {{tt|u1}} and {{tt|u2}} such that {{c|decltype((t1))}} and {{c|decltype((t2))}} are both {{tt|T}} and {{c|decltype((u1))}} and {{c|decltype((u2))}} are both {{tt|U}},
* {{c|std::common_type_t<T, U>(t1)}} equals {{c|std::common_type_t<T, U>(t2)}} if and only if {{tt|t1}} equals {{tt|t2}}; and
* {{c|std::common_type_t<T, U>(u1)}} equals {{c|std::common_type_t<T, U>(u2)}} if and only if {{tt|u1}} equals {{tt|u2}}.

In other words, the conversion to the common type must [[cpp/concepts#Equality preservation|preserve equality]].

{{cpp/concepts/equality preservation|skip-requires=yes}}