LWG3661 constinit atomic<shared_ptr<T>> a(nullptr); should work

Author: jensmaurer

source/atomics.tex

@@ -2801,6 +2801,7 @@
     bool is_lock_free() const noexcept;
 
     constexpr atomic() noexcept;
+    constexpr atomic(nullptr_t) noexcept : atomic() { }
     atomic(shared_ptr<T> desired) noexcept;
     atomic(const atomic&) = delete;
     void operator=(const atomic&) = delete;