Proposed resolution:

This wording is relative to N4917.

1. Modify [container.adaptors.general] as indicated:

   -8- The following exposition-only alias template may appear in deduction guides for container adaptors:

   template<class Allocator, class T>
     using alloc-rebind =                                 // exposition only
       typename allocator_traits<Allocator>::template rebind_alloc<T>;
   
   

2. Modify [flat.map.defn], class template flat_map synopsis, as indicated:

   […]
   template<ranges::input_range R, class Compare = less<range-key-type<R>>,
            class Allocator = allocator<byte>>
     flat_map(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
       -> flat_map<range-key-type<R>, range-mapped-type<R>, Compare,
            vector<range-key-type<R>, alloc-rebind<Allocator, range-key-type<R>>>,
            vector<range-mapped-type<R>, alloc-rebind<Allocator, range-mapped-type<R>>>>;
   
   template<ranges::input_range R, class Allocator>
     flat_map(from_range_t, R&&, Allocator)
       -> flat_map<range-key-type<R>, range-mapped-type<R>, less<range-key-type<R>>,
            vector<range-key-type<R>, alloc-rebind<Allocator, range-key-type<R>>>,
            vector<range-mapped-type<R>, alloc-rebind<Allocator, range-mapped-type<R>>>>;
   […]
   

3. Modify [flat.multimap.defn], class template flat_multimap synopsis, as indicated:

   […]
   template<ranges::input_range R, class Compare = less<range-key-type<R>>,
            class Allocator = allocator<byte>>
     flat_multimap(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
       -> flat_multimap<range-key-type<R>, range-mapped-type<R>, Compare,
            vector<range-key-type<R>, alloc-rebind<Allocator, range-key-type<R>>>,
            vector<range-mapped-type<R>, alloc-rebind<Allocator, range-mapped-type<R>>>>;
   
   template<ranges::input_range R, class Allocator>
     flat_multimap(from_range_t, R&&, Allocator)
       -> flat_multimap<range-key-type<R>, range-mapped-type<R>, less<range-key-type<R>>,
            vector<range-key-type<R>, alloc-rebind<Allocator, range-key-type<R>>>,
            vector<range-mapped-type<R>, alloc-rebind<Allocator, range-mapped-type<R>>>>;
   […]
   

4. Modify [flat.set.defn], class template flat_set synopsis, as indicated:

   […]
   template<ranges::input_range R, class Compare = less<ranges::range_value_t<R>>,
            class Allocator = allocator<ranges::range_value_t<R>>>
     flat_set(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
       -> flat_set<ranges::range_value_t<R>, Compare,
            vector<ranges::range_value_t<R>, alloc-rebind<Allocator, ranges::range_value_t<R>>>>;
   
   template<ranges::input_range R, class Allocator>
     flat_set(from_range_t, R&&, Allocator)
       -> flat_set<ranges::range_value_t<R>, less<ranges::range_value_t<R>>,
            vector<ranges::range_value_t<R>, alloc-rebind<Allocator, ranges::range_value_t<R>>>>;
   […]
   

5. Modify [flat.multiset.defn], class template flat_multiset synopsis, as indicated:

   […]
   template<ranges::input_range R, class Compare = less<ranges::range_value_t<R>>,
            class Allocator = allocator<ranges::range_value_t<R>>>
     flat_multiset(from_range_t, R&&, Compare = Compare(), Allocator = Allocator())
       -> flat_multiset<ranges::range_value_t<R>, Compare,
            vector<ranges::range_value_t<R>, alloc-rebind<Allocator, ranges::range_value_t<R>>>>;
   
   template<ranges::input_range R, class Allocator>
     flat_multiset(from_range_t, R&&, Allocator)
       -> flat_multiset<ranges::range_value_t<R>, less<ranges::range_value_t<R>>,
            vector<ranges::range_value_t<R>, alloc-rebind<Allocator, ranges::range_value_t<R>>>>;
   […]