From 06defa27d3c3ea0cd3c3f4afef31fc486fa30037 Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34@live.cn>
Date: Mon, 23 Dec 2024 08:48:57 +0800
Subject: [PATCH] Implement LWG-4144

---
 stl/inc/memory | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/stl/inc/memory b/stl/inc/memory
index 864f44f90af..88b630d8ead 100644
--- a/stl/inc/memory
+++ b/stl/inc/memory
@@ -3329,9 +3329,17 @@ template <class _Dx2>
 using _Unique_ptr_enable_default_t =
     enable_if_t<conjunction_v<negation<is_pointer<_Dx2>>, is_default_constructible<_Dx2>>, int>;
 
+template <class, class = void>
+constexpr bool _Can_form_pointer = false;
+template <class _Ty>
+constexpr bool _Can_form_pointer<_Ty, void_t<_Ty*>> = true;
+
 _EXPORT_STD template <class _Ty, class _Dx /* = default_delete<_Ty> */>
 class unique_ptr { // non-copyable pointer to an object
 public:
+    static_assert(_Can_form_pointer<_Ty>,
+        "unique_ptr<T, D> requires T* to be a valid type (N5001 [unique.ptr.single.general]/1).");
+
     using pointer      = typename _Get_deleter_pointer_type<_Ty, remove_reference_t<_Dx>>::type;
     using element_type = _Ty;
     using deleter_type = _Dx;