25 Iterators library [iterators]

25.3 Iterator requirements [iterator.requirements]

25.3.7 Common algorithm requirements [alg.req] Concept indirectly_movable [alg.req.ind.move]

The indirectly_movable concept specifies the relationship between an indirectly_readable type and an indirectly_writable type between which values may be moved.
template<class In, class Out> concept indirectly_movable = indirectly_readable<In> && indirectly_writable<Out, iter_rvalue_reference_t<In>>;
The indirectly_movable_storable concept augments indirectly_movable with additional requirements enabling the transfer to be performed through an intermediate object of the indirectly_readable type's value type.
template<class In, class Out> concept indirectly_movable_storable = indirectly_movable<In, Out> && indirectly_writable<Out, iter_value_t<In>> && movable<iter_value_t<In>> && constructible_from<iter_value_t<In>, iter_rvalue_reference_t<In>> && assignable_from<iter_value_t<In>&, iter_rvalue_reference_t<In>>;
Let i be a dereferenceable value of type In.
In and Out model indirectly_movable_storable<In, Out> only if after the initialization of the object obj in iter_value_t<In> obj(ranges::iter_move(i)); obj is equal to the value previously denoted by *i.
If iter_rvalue_reference_t<In> is an rvalue reference type, the resulting state of the value denoted by *i is valid but unspecified ([lib.types.movedfrom]).