Proposed resolution:

This wording is relative to N4750.

[Drafting note: The subclause only uses OUTERMOST_ALLOC_TRAITS(*this) and only in non-const member functions, so the result is also non-const. Thus, remove_reference_t is sufficient; there's no need to further remove cv-qualification. — end drafting note]

1. Modify [allocator.adaptor.members]p1 as indicated:

   -1- In the construct member functions, OUTERMOST(x) is x if x does not have an outer_allocator() member function and OUTERMOST(x.outer_allocator()) if the expression x.outer_allocator() is valid ([temp.deduct]) and x otherwise; OUTERMOST_ALLOC_TRAITS(x) is allocator_traits<remove_reference_t<decltype(OUTERMOST(x))>>. [Note: […] — end note]