Proposed resolution:

This wording is relative to N5032.

1. Modify [util.smartptr.shared.general], class template `shared_ptr` synopsis, as indicated:

   namespace std {
     template<class T> class shared_ptr {
     public:
       […]
       template<class U>
         constexpr bool owner_before(const shared_ptr<U>& b) const noexcept;
       template<class U>
         constexpr bool owner_before(const weak_ptr<U>& b) const noexcept;
       size_t owner_hash() const noexcept;
       template<class U>
         constexpr bool owner_equal(const shared_ptr<U>& b) const noexcept;
       template<class U>
         constexpr bool owner_equal(const weak_ptr<U>& b) const noexcept;
     };
   
     […]
   }
   

2. Modify [util.smartptr.shared.obs] as indicated:

   template<class U> constexpr bool owner_before(const shared_ptr<U>& b) const noexcept;
   template<class U> constexpr bool owner_before(const weak_ptr<U>& b) const noexcept;
   

   -19- […]

3. Modify [util.smartptr.weak.general], class template `weak_ptr` synopsis, as indicated:

   namespace std {
     template<class T> class weak_ptr {
     public:
       […]
       template<class U>
         constexpr bool owner_before(const shared_ptr<U>& b) const noexcept;
       template<class U>
         constexpr bool owner_before(const weak_ptr<U>& b) const noexcept;
       size_t owner_hash() const noexcept;
       template<class U>
         constexpr bool owner_equal(const shared_ptr<U>& b) const noexcept;
       template<class U>
         constexpr bool owner_equal(const weak_ptr<U>& b) const noexcept;
     };
   
     […]
   }
   

4. Modify [util.smartptr.weak.obs] as indicated:

   template<class U> constexpr bool owner_before(const shared_ptr<U>& b) const noexcept;
   template<class U> constexpr bool owner_before(const weak_ptr<U>& b) const noexcept;
   

   -4- […]

5. Modify [util.smartptr.ownerless], class template `owner_less` synopsis, as indicated:

   namespace std {
     template<class T = void> struct owner_less;
   
     template<class T> struct owner_less<shared_ptr<T>> {
       constexpr bool operator()(const shared_ptr<T>&, const shared_ptr<T>&) const noexcept;
       constexpr bool operator()(const shared_ptr<T>&, const weak_ptr<T>&) const noexcept;
       constexpr bool operator()(const weak_ptr<T>&, const shared_ptr<T>&) const noexcept;
     };
   
     template<class T> struct owner_less<weak_ptr<T>> {
       constexpr bool operator()(const weak_ptr<T>&, const weak_ptr<T>&) const noexcept;
       constexpr bool operator()(const shared_ptr<T>&, const weak_ptr<T>&) const noexcept;
       constexpr bool operator()(const weak_ptr<T>&, const shared_ptr<T>&) const noexcept;
     };
   
     template<> struct owner_less<void> {
       template<class T, class U>
         constexpr bool operator()(const shared_ptr<T>&, const shared_ptr<U>&) const noexcept;
       template<class T, class U>
         constexpr bool operator()(const shared_ptr<T>&, const weak_ptr<U>&) const noexcept;
       template<class T, class U>
         constexpr bool operator()(const weak_ptr<T>&, const shared_ptr<U>&) const noexcept;
       template<class T, class U>
         constexpr bool operator()(const weak_ptr<T>&, const weak_ptr<U>&) const noexcept;
   
       using is_transparent = unspecified;
     };
   }
   

[ Croydon 2026-03-25; move to Immediate. ]

Addresses US 75-138

LEWG decided to remove `constexpr` from `owner_before` and `owner_less`.