22 General utilities library [utilities]

22.10 Function objects [function.objects]

22.10.17 Polymorphic function wrappers [func.wrap]

22.10.17.6 Non-owning wrapper [func.wrap.ref]

22.10.17.6.4 Invocation [func.wrap.ref.inv]

R operator()(ArgTypes... args) const noexcept(noex);
Effects: Equivalent to: return thunk-ptr(bound-entity, std​::​forward<ArgTypes>(args)...);