Clear references to map data on level change

These shouldn't be left as they'll now point towards potentially invalid memory and also cause errors with serializing. Arrays and maps holding them are cleared. Also unlinks and relinks inventory items correctly from the hashmap on traveling.

src/common/objects/dobject.cpp

@@ -417,6 +417,67 @@ size_t DObject::PropagateMark()
 //
 //==========================================================================
 
+void DObject::ClearNativePointerFields(const TArray<FName>& types)
+{
+	auto cls = GetClass();
+	if (cls->VMType == nullptr)
+		return;
+
+	auto it = cls->VMType->Symbols.GetIterator();
+	TMap<FName, PSymbol*>::Pair* sym = nullptr;
+	while (it.NextPair(sym))
+	{
+		auto field = dyn_cast<PField>(sym->Value);
+		if (field == nullptr)
+			continue;
+
+		PType* base = field->Type;
+		PType* t = base;
+		if (base->isArray() && !base->isStaticArray())
+			t = static_cast<PArray*>(base)->ElementType;
+		else if (base->isDynArray())
+			t = static_cast<PDynArray*>(base)->ElementType;
+		else if (base->isMap())
+			t = static_cast<PMap*>(base)->ValueType;
+
+		if (!t->isRealPointer())
+			continue;
+
+		auto pType = static_cast<PPointer*>(t)->PointedType;
+		if (!pType->isStruct() || !static_cast<PStruct*>(pType)->isNative || types.Find(static_cast<PStruct*>(pType)->TypeName) >= types.Size())
+			continue;
+
+		if (base->isArray() && !base->isStaticArray())
+		{
+			auto arr = (void**)ScriptVar(sym->Key, nullptr);
+			const size_t count = static_cast<PArray*>(base)->ElementCount;
+			for (size_t i = 0u; i < count; ++i)
+				arr[i] = nullptr;
+		}
+		else if (base->isDynArray())
+		{
+			static_cast<TArray<void*>*>(ScriptVar(sym->Key, nullptr))->Clear();
+		}
+		else if (base->isMap())
+		{
+			if (static_cast<PMap*>(base)->BackingClass == PMap::MAP_I32_PTR)
+				static_cast<ZSMap<int, void*>*>(ScriptVar(sym->Key, nullptr))->Clear();
+			else
+				static_cast<ZSMap<FString, void*>*>(ScriptVar(sym->Key, nullptr))->Clear();
+		}
+		else
+		{
+			PointerVar<void>(sym->Key) = nullptr;
+		}
+	}
+}
+
+//==========================================================================
+//
+//
+//
+//==========================================================================
+
 template<typename M>
 static void MapPointerSubstitution(M *map, size_t &changed, DObject *old, DObject *notOld, const bool shouldSwap)
 {

src/common/objects/dobject.h

@@ -245,6 +245,9 @@ public:
 	template<class T> T*& PointerVar(FName field);
 	inline int* IntArray(FName field);
 
+	// Make sure native data is wiped correctly since it has no read barriers.
+	void ClearNativePointerFields(const TArray<FName>& types);
+
 	// This is only needed for swapping out PlayerPawns and absolutely nothing else!
 	virtual size_t PointerSubstitution (DObject *old, DObject *notOld, bool nullOnFail);