23 Ranges library [ranges]

23.8 Range adaptors [range.adaptors]

23.8.4 Filter view [range.filter]

23.8.4.5 view​::​filter [range.filter.adaptor]

The name view::filter denotes a range adaptor object ([range.adaptor.object]).
For some subexpressions E and P, the expression view::filter(E, P) is expression-equivalent to filter_­view{E, P}.