From 343687b50d50a77d5c86686b609cd04dbd8b230d Mon Sep 17 00:00:00 2001
From: Speeder <ek.speeder@gmail.com>
Date: Sat, 24 Jan 2026 19:51:51 +0100
Subject: [PATCH] Fixed undefined state after Reset/Inject call

The instance's Emplace and SetExtern methods called the dtor, which could set the instance into an undefined state.
Moved cleanup from the dtor function into a dedicated method to avoid the dtor's object-lifetime ending effect.
---
 include/singleton.hpp | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/include/singleton.hpp b/include/singleton.hpp
index 9b34122..3d04dc3 100644
--- a/include/singleton.hpp
+++ b/include/singleton.hpp
@@ -76,9 +76,7 @@ struct Singleton
         Instance(const Instance&) = delete;
         ~Instance()
         {
-            // Destroys the locally-initialized instance. Injected ones are ignored (no ownership).
-            if (m_pExtern == LOCAL_INSTANCE_ID)
-                GetBuffer().~T();
+            DestroyLocalInstance();
         }
         Instance& operator =(const Instance&) = delete;
         /// Returns the current instance.
@@ -91,7 +89,7 @@ struct Singleton
         template <typename ...Args>
         void Emplace(Args&&... args)
         {
-            this->~Instance();
+            DestroyLocalInstance();
             try
             {
                 new (&GetBuffer()) T(std::forward<Args>(args)...);
@@ -108,7 +106,7 @@ struct Singleton
           */
         void SetExtern(T* ptr)
         {
-            this->~Instance();
+            DestroyLocalInstance();
             m_pExtern = ptr;
         }
     private:
@@ -123,6 +121,13 @@ struct Singleton
             // Static, uninitialized buffer for the singleton's object
             static union U { T asT; U(){} ~U(){} } buffer;
             return buffer.asT;
+        }
+		/// Destroys the local instance, while ignoring injected ones (no ownership).
+        /** @remark This leaves the object in an inconsistent state. m_pExtern must be changed. */
+        void DestroyLocalInstance()
+        {
+            if (m_pExtern == LOCAL_INSTANCE_ID)
+                GetBuffer().~T();
         }
     } g_instance;