From 904075e1f19bfeece987698885d1008f85491697 Mon Sep 17 00:00:00 2001
From: Sokolov Yura <funny.falcon@gmail.com>
Date: Thu, 23 Nov 2023 06:49:10 +0300
Subject: [PATCH] AutoPtr: do 'duplicate' before 'release' (#4068)

Common knowledge in reference counting is "on assignment increment first
then decrement", because "just to be deleted" object could hold last
reference to "just to be assigned" one.

Fixes #3979
---
 Foundation/include/Poco/AutoPtr.h | 23 ++++++-----------------
 1 file changed, 6 insertions(+), 17 deletions(-)

diff --git a/Foundation/include/Poco/AutoPtr.h b/Foundation/include/Poco/AutoPtr.h
index 8251f4669..27f68a6b6 100644
--- a/Foundation/include/Poco/AutoPtr.h
+++ b/Foundation/include/Poco/AutoPtr.h
@@ -110,34 +110,23 @@ public:
 	{
 		if (_ptr != ptr)
 		{
-			if (_ptr) _ptr->release();
-			_ptr = ptr;
-			if (shared && _ptr) _ptr->duplicate();
+			if (shared && ptr) ptr->duplicate();
+			std::swap(_ptr, ptr);
+			if (ptr) ptr->release();
 		}
 		return *this;
 	}
 
 	AutoPtr& assign(const AutoPtr& ptr)
 	{
-		if (&ptr != this)
-		{
-			if (_ptr) _ptr->release();
-			_ptr = ptr._ptr;
-			if (_ptr) _ptr->duplicate();
-		}
-		return *this;
+		return assign(ptr._ptr, true);
 	}
 
 	template <class Other>
 	AutoPtr& assign(const AutoPtr<Other>& ptr)
 	{
-		if (ptr.get() != _ptr)
-		{
-			if (_ptr) _ptr->release();
-			_ptr = const_cast<Other*>(ptr.get());
-			if (_ptr) _ptr->duplicate();
-		}
-		return *this;
+		C* nptr = const_cast<Other*>(ptr.get());
+		return assign(nptr, true);
 	}
 
 	void reset()