std::experimental::ranges::IndirectRelation
Min standard notice:
Header: <experimental/ranges/iterator>
# Declarations
template< class F, class I1, class I2 = I1 >
concept bool IndirectRelation =
Readable<I1> && Readable<I2> &&
CopyConstructible<F> &&
Relation<F&, ranges::value_type_t<I1>&, ranges::value_type_t<I2>&> &&
Relation<F&, ranges::value_type_t<I1>&, ranges::reference_t<I2>> &&
Relation<F&, ranges::reference_t<I1>, ranges::value_type_t<I2>&> &&
Relation<F&, ranges::reference_t<I1>, ranges::reference_t<I2>> &&
Relation<F&, ranges::iter_common_reference_t<I1>, ranges::iter_common_reference_t<I2>>;
(ranges TS)