Proposed resolution:

This wording is relative to N5014.

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

   […]
   namespace std::ranges {
     […]
     // [range.utility.conv], range conversions
     template<class C, input_range R, class... Args> requires (!view<C>)
       constexpr C to(R&& r, Args&&... args);
     template<template<class...> class C, input_range R, class... Args>
       constexpr auto to(R&& r, Args&&... args);
     template<class C, class... Args> requires (!view<C>)
       constexpr auto to(Args&&... args);
     template<template<class...> class C, class... Args>
       constexpr auto to(Args&&... args);  
     […]
   }
   

2. Modify [range.utility.conv.to] as indicated:

   template<template<class...> class C, input_range R, class... Args>
     constexpr auto to(R&& r, Args&&... args);
   

   -3- Let input-iterator be an exposition-only type:

   
   struct input-iterator { // exposition only
     using iterator_category = input_iterator_tag;
     using value_type = range_value_t<R>;
     using difference_type = ptrdiff_t;
     using pointer = add_pointer_t<range_reference_t<R>>;
     using reference = range_reference_t<R>;
     reference operator*() const;
     pointer operator->() const;
     input-iterator& operator++();
     input-iterator operator++(int);
     bool operator==(const input-iterator&) const;
   };
   

   [Note 1: input-iterator meets the syntactic requirements of Cpp17InputIterator. — end note]

   -4- Let DEDUCE_EXPR be defined as follows:

   1. (4.1) — C(declval<R>(), declval<Args>()...) if that is a valid expression,

   2. (4.2) — otherwise, C(from_range, declval<R>(), declval<Args>()...) if that is a valid expression,

   3. (4.3) — otherwise,

      
      C(declval<input-iterator>(), declval<input-iterator>(), declval<Args>()...)
      

      if that is a valid expression,

   4. (4.4) — otherwise, the program is ill-formed.

   -5- Returns: to<decltype(DEDUCE_EXPR)>(std::forward<R>(r), std::forward<Args>(args)...).

[range.utility.conv.to] p4 defines a DEDUCE_EXPR that attempts CTAD (class template argument deduction) on a template template parameter `C`.

This is not supported by the core language; CWG 3003 will clarify the core wording accordingly.

Suggested resolution: Remove [range.utility.conv.to] p3, p4, p5 and the respective entry in the synopsis as unimplementable.