Proposed resolution:

This wording is relative to N4885.

1. Modify [format.syn], header <format> synopsis, as indicated:

   […]
   // [format.arg.store], class template format-arg-store
   template<class Context, class... Args> structclass format-arg-store; // exposition only
   
   template<class Context = format_context, class... Args>
     format-arg-store<Context, Args...>
       make_format_args(const Args&... fmt_args);
   […]
   

2. Modify [format.arg.store] as indicated:

   namespace std {
     template<class Context, class... Args>
     structclass format-arg-store { // exposition only
       array<basic_format_arg<Context>, sizeof...(Args)> args; // exposition only
     };
   }
   

   -1- An instance of format-arg-store stores formatting arguments.

   template<class Context = format_context, class... Args>
     format-arg-store<Context, Args...> make_format_args(const Args&... fmt_args);
   

   -2- Preconditions: The type typename Context::template formatter_type<T_i> meets the Formatter requirements ([formatter.requirements]) for each T_i in Args.

   -3- Returns: An object of type format-arg-store<Context, Args...> whose args data member is initialized with {basic_format_arg<Context>(fmt_args)...}.