## Summary - Implements LWG4472, i.e., adds a deleted `atomic_ref(T&&)` overload to the primary template and three partial specializations of `atomic_ref`. ## Test - Added `static_assert`s in `ctor.pass.cpp` asserting `atomic_ref<T>`/`atomic_ref<const T>` reject construction from `T&&`/`const T&&`. Resolve #189840