From 9ddc40f4cecc6c170b8ec2d651a423f9f326a7b4 Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34@live.cn>
Date: Mon, 13 Nov 2023 23:22:57 +0800
Subject: [PATCH 1/2] Implement LWG-3897 `inout_ptr` will not update raw
 pointer to null

---
 stl/inc/memory                           | 18 ++++++++++--------
 tests/std/tests/P1132R7_out_ptr/test.cpp | 13 +++++++++++++
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/stl/inc/memory b/stl/inc/memory
index 3cc2b661cad..f448b6f9a8e 100644
--- a/stl/inc/memory
+++ b/stl/inc/memory
@@ -4246,20 +4246,22 @@ public:
             _Smart_ptr.release();
         }
 
-        if (!_Get_ptr()) {
-            return;
-        }
-
         _STD apply(
             [this](auto&&... _Args_) {
                 using _Sp = _Pointer_of_or<_SmartPtr, _Pointer>;
                 if constexpr (is_pointer_v<_SmartPtr>) {
                     _Smart_ptr = _SmartPtr(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
-                } else if constexpr (_Resettable_pointer<_SmartPtr, _Sp, _Pointer, _ArgsT...>) {
-                    _Smart_ptr.reset(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
                 } else {
-                    static_assert(is_constructible_v<_SmartPtr, _Sp, _ArgsT...>, "(N4950 [inout.ptr.t]/11.4)");
-                    _Smart_ptr = _SmartPtr(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
+                    if (!_Get_ptr()) {
+                        return;
+                    }
+
+                    if constexpr (_Resettable_pointer<_SmartPtr, _Sp, _Pointer, _ArgsT...>) {
+                        _Smart_ptr.reset(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
+                    } else {
+                        static_assert(is_constructible_v<_SmartPtr, _Sp, _ArgsT...>, "(N4950 [inout.ptr.t]/11.4)");
+                        _Smart_ptr = _SmartPtr(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
+                    }
                 }
             },
             _STD move(_Get_args()));
diff --git a/tests/std/tests/P1132R7_out_ptr/test.cpp b/tests/std/tests/P1132R7_out_ptr/test.cpp
index c73a1f0726b..ddb55846ed7 100644
--- a/tests/std/tests/P1132R7_out_ptr/test.cpp
+++ b/tests/std/tests/P1132R7_out_ptr/test.cpp
@@ -33,6 +33,19 @@ void test_raw_ptr() {
 
         assert(*int_ptr == 15);
     }
+    // LWG-3897 inout_ptr will not update raw pointer to null
+    {
+        const auto delete_nullify = [](int** ptr) {
+            delete *ptr;
+            *ptr = nullptr;
+        };
+
+        int* ptr_allocated = new int{};
+
+        delete_nullify(inout_ptr(ptr_allocated));
+
+        assert(ptr_allocated == nullptr);
+    }
 }
 
 void test_shared_ptr() {

From c8f6d03b8bc84396e7864378ed78f6c5fc3a63ed Mon Sep 17 00:00:00 2001
From: "Stephan T. Lavavej" <stl@nuwen.net>
Date: Mon, 13 Nov 2023 14:21:19 -0800
Subject: [PATCH 2/2] Code review feedback: Simplify control flow.

---
 stl/inc/memory | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/stl/inc/memory b/stl/inc/memory
index f448b6f9a8e..b65377e6390 100644
--- a/stl/inc/memory
+++ b/stl/inc/memory
@@ -4244,6 +4244,10 @@ public:
     ~inout_ptr_t() {
         if constexpr (!is_pointer_v<_SmartPtr>) {
             _Smart_ptr.release();
+
+            if (!_Get_ptr()) {
+                return;
+            }
         }
 
         _STD apply(
@@ -4251,17 +4255,11 @@ public:
                 using _Sp = _Pointer_of_or<_SmartPtr, _Pointer>;
                 if constexpr (is_pointer_v<_SmartPtr>) {
                     _Smart_ptr = _SmartPtr(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
+                } else if constexpr (_Resettable_pointer<_SmartPtr, _Sp, _Pointer, _ArgsT...>) {
+                    _Smart_ptr.reset(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
                 } else {
-                    if (!_Get_ptr()) {
-                        return;
-                    }
-
-                    if constexpr (_Resettable_pointer<_SmartPtr, _Sp, _Pointer, _ArgsT...>) {
-                        _Smart_ptr.reset(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
-                    } else {
-                        static_assert(is_constructible_v<_SmartPtr, _Sp, _ArgsT...>, "(N4950 [inout.ptr.t]/11.4)");
-                        _Smart_ptr = _SmartPtr(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
-                    }
+                    static_assert(is_constructible_v<_SmartPtr, _Sp, _ArgsT...>, "(N4950 [inout.ptr.t]/11.4)");
+                    _Smart_ptr = _SmartPtr(static_cast<_Sp>(_Get_ptr()), _STD forward<_ArgsT>(_Args_)...);
                 }
             },
             _STD move(_Get_args()));