Use the deferred virtual call mechanism to avoid the virtual

call bug in the constructor.

See docs/wrong_virtual_call.md for a description.

docs/wrong_virtual_call.md

@@ -0,0 +1,25 @@
+1) SizeNotifiable, defined as the following:
+
+    class SizeNotifiable<RegisterBehaviour, true> : private RegisterBehaviour, public SizeNotifiableBase { ... };
+
+gets constructed - it inherits from SizeNotifiableBase which declares NotifyResChanged() as virtual. It also inherits from RegisterBehaviour, which must provide a Register() method.
+
+2) In SizeNotifiable's constructor RegisterBehaviour::Register(this) gets called. Being in the constructor, virtual calls on this are UB.
+
+3) When RegisterBehaviour == AutoRegister, we have Register defined as the following:
+
+    void AutoRegister::Register (SizeNotifiableBase* parNotifiable) {
+        m_id = m_sdlmain->RegisterForResChange(parNotifiable);
+    }
+
+note that parNotifiable is received from SizeNotifiable's constructor, so it's a partially constructed object.
+
+4) RegisterForResChange() is defined as:
+
+    size_t SDLMain::RegisterForResChange (SizeNotifiableBase* parNotif) {
+        parNotif->NotifyResChanged(m_localData->sizeratio);
+        return m_localData->resChangeNotifList.Add(parNotif);
+    }
+
+parNotif is, again, the partly constructed object pointed by this in SizeNotifiable's constructor. NotifyResChanged() is a virtual method, thus the bug.
+Objects being registered need to be notified straight away since they have no clue about the current size held by SDLMain.

src/character.cpp

@@ -43,7 +43,7 @@ namespace cloonel {
 		Placeable(float2(0.0f)),
 		Drawable(parSize),
 		m_bottomBar(float2(0.0f), parSize.x()),
-		m_screenRatio(parMain),
+		m_screenRatio(parMain, DeferredRegister(&m_screenRatio)),
 		m_bounceCallback(&DoNothing),
 		m_texture(new Texture(parPath, parMain, false))
 #if defined(WITH_DEBUG_VISUALS)

src/platform.cpp

@@ -28,7 +28,7 @@ namespace cloonel {
 	///--------------------------------------------------------------------------
 	Platform::Platform (SDLMain* parSdlMain, const float2& parPos, Texture* parTexture, const float2& parSize) :
 		Placeable(parPos),
-		m_screenRatio(parSdlMain),
+		m_screenRatio(parSdlMain, &m_screenRatio),
 		m_size(parSize),
 		m_collisionTop(new HorzCollisionBar(parPos, parSize.x())),
 		m_surface(parTexture)

src/sizenotifiable.cpp

@@ -1,8 +1,8 @@
 #include "sizenotifiable.hpp"
 #include "sizeratio.hpp"
 #include "sdlmain.hpp"
-#include <cassert>
 #include <ciso646>
+#include <exception>
 
 namespace cloonel {
 	namespace implem {
@@ -62,4 +62,12 @@ namespace cloonel {
 	///--------------------------------------------------------------------------
 	void SizeNotifiableBase::OnResChanged (const SizeRatio&) {
 	}
+
+	///--------------------------------------------------------------------------
+	///--------------------------------------------------------------------------
+	DeferredRegister::~DeferredRegister() {
+		assert(m_call);
+		if (not std::uncaught_exception())
+			m_call();
+	}
 } //namespace cloonel

src/sizenotifiable.hpp

@@ -24,6 +24,7 @@
 #include <cstddef>
 #include <algorithm>
 #include <functional>
+#include <cassert>
 
 namespace cloonel {
 	class SizeRatio;
@@ -69,6 +70,19 @@ namespace cloonel {
 		};
 	} //namespace regbehaviours
 
+	template <class RegisterBehaviour, bool=RegisterBehaviour::SDLMAIN_NEEDED>
+	class SizeNotifiable;
+
+	class DeferredRegister {
+	public:
+		template <typename R>
+		DeferredRegister ( SizeNotifiable<R>* parObject ) noexcept;
+		~DeferredRegister ( void );
+
+	private:
+		std::function<void()> m_call;
+	};
+
 	class SizeNotifiableBase {
 	protected:
 		SizeNotifiableBase ( void ) = default;
@@ -86,12 +100,10 @@ namespace cloonel {
 		float2 m_scaleRatio;
 	};
 
-	template <class RegisterBehaviour, bool=RegisterBehaviour::SDLMAIN_NEEDED>
-	class SizeNotifiable;
-
 	template <class RegisterBehaviour>
 	class SizeNotifiable<RegisterBehaviour, false> : private RegisterBehaviour, public SizeNotifiableBase {
 		static_assert(RegisterBehaviour::SDLMAIN_NEEDED == false, "SdlMainNeeded mismatches expected value");
+		friend class DeferredRegister;
 	public:
 		SizeNotifiable ( const SizeNotifiable& ) = delete;
 		SizeNotifiable ( SizeNotifiable&& parOther ) :
@@ -99,8 +111,8 @@ namespace cloonel {
 			SizeNotifiableBase(parOther)
 		{
 		}
-		SizeNotifiable ( void ) {
+		explicit SizeNotifiable ( const DeferredRegister& parRegisterFunctor ) {
-			this->Register(this);
+			static_cast<void>(parRegisterFunctor);
 		}
 		virtual ~SizeNotifiable ( void ) noexcept {
 			this->Unregister();
@@ -110,6 +122,7 @@ namespace cloonel {
 	template <class RegisterBehaviour>
 	class SizeNotifiable<RegisterBehaviour, true> : private RegisterBehaviour, public SizeNotifiableBase {
 		static_assert(RegisterBehaviour::SDLMAIN_NEEDED == true, "SdlMainNeeded mismatches expected value");
+		friend class DeferredRegister;
 	public:
 		SizeNotifiable ( const SizeNotifiable& ) = delete;
 		SizeNotifiable ( SizeNotifiable&& parOther ) :
@@ -117,15 +130,22 @@ namespace cloonel {
 			SizeNotifiableBase(parOther)
 		{
 		}
-		explicit SizeNotifiable ( SDLMain* parSdlMain ) :
+		SizeNotifiable ( SDLMain* parSdlMain, const DeferredRegister& parRegisterFunctor ) :
 			RegisterBehaviour(parSdlMain)
 		{
-			this->Register(this);
+			static_cast<void>(parRegisterFunctor);
 		}
 		virtual ~SizeNotifiable ( void ) noexcept {
 			this->Unregister();
 		}
 	};
+
+	template <typename R>
+	DeferredRegister::DeferredRegister (SizeNotifiable<R>* parObject) noexcept :
+		m_call(std::bind(&R::Register, static_cast<R*>(parObject), parObject))
+	{
+		assert(m_call);
+	}
 } //namespace cloonel
 
 #endif

src/tiledwallpaper.cpp

@@ -98,7 +98,7 @@ namespace cloonel {
 	///--------------------------------------------------------------------------
 	///--------------------------------------------------------------------------
 	TiledWallpaper::TileCountNotifiable::TileCountNotifiable (SDLMain* parMain, const ushort2& parTileSize) :
-		BaseClass(parMain),
+		BaseClass(parMain, this),
 		m_tileCount(CountTilesInScreen(parMain->WidthHeight(), parTileSize)),
 		m_tileSize(vector_cast<float2>(parTileSize))
 #if defined(WITH_DEBUG_VISUALS)