LWG-3548 shared_ptr construction from unique_ptr should move (not copy) the deleter (#2007)

Co-authored-by: Stephan T. Lavavej <[email protected]>

Author: AdamBucior

stl/inc/memory

@@ -1642,7 +1642,8 @@ public:
 
         if (_Fancy) {
             const _Raw_t _Raw = _Fancy;
-            const auto _Rx    = new _Ref_count_resource<_Fancy_t, _Deleter_t>(_Fancy, _Other.get_deleter());
+            const auto _Rx =
+                new _Ref_count_resource<_Fancy_t, _Deleter_t>(_Fancy, _STD forward<_Dx>(_Other.get_deleter()));
             _Set_ptr_rep_and_enable_shared(_Raw, _Rx);
             _Other.release();
         }

tests/std/tests/Dev10_722102_shared_ptr_nullptr/test.cpp

@@ -211,6 +211,14 @@ namespace unique_ptr_ {
             assert(*ptr.ptr_ == 42);
             *ptr.ptr_ = 13;
         }
+
+        // Also test LWG-3548 "shared_ptr construction from unique_ptr should move (not copy) the deleter".
+        fancy_deleter()                = default;
+        fancy_deleter(fancy_deleter&&) = default;
+
+        fancy_deleter(const fancy_deleter&) = delete;
+        fancy_deleter& operator=(fancy_deleter&&) = delete;
+        fancy_deleter& operator=(const fancy_deleter&) = delete;
     };
 
     template <class>