From 88df025aa0ab92ed176f91dd835c004fa26f0ed0 Mon Sep 17 00:00:00 2001
From: David Snopek <dsnopek@gmail.com>
Date: Tue, 7 May 2024 12:54:35 -0500
Subject: Clean up instance bindings for engine singletons to prevent crash

---
 src/core/class_db.cpp | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

(limited to 'src/core')

diff --git a/src/core/class_db.cpp b/src/core/class_db.cpp
index acead8b..d9a8bf9 100644
--- a/src/core/class_db.cpp
+++ b/src/core/class_db.cpp
@@ -43,6 +43,8 @@ namespace godot {
 std::unordered_map<StringName, ClassDB::ClassInfo> ClassDB::classes;
 std::unordered_map<StringName, const GDExtensionInstanceBindingCallbacks *> ClassDB::instance_binding_callbacks;
 std::vector<StringName> ClassDB::class_register_order;
+std::unordered_map<StringName, Object *> ClassDB::engine_singletons;
+std::mutex ClassDB::engine_singletons_mutex;
 GDExtensionInitializationLevel ClassDB::current_level = GDEXTENSION_INITIALIZATION_CORE;
 
 MethodDefinition D_METHOD(StringName p_name) {
@@ -419,6 +421,22 @@ void ClassDB::deinitialize(GDExtensionInitializationLevel p_level) {
 		});
 		class_register_order.erase(it, class_register_order.end());
 	}
+
+	if (p_level == GDEXTENSION_INITIALIZATION_CORE) {
+		// Make a new list of the singleton objects, since freeing the instance bindings will lead to
+		// elements getting removed from engine_singletons.
+		std::vector<Object *> singleton_objects;
+		{
+			std::lock_guard<std::mutex> lock(engine_singletons_mutex);
+			singleton_objects.reserve(engine_singletons.size());
+			for (const std::pair<StringName, Object *> &pair : engine_singletons) {
+				singleton_objects.push_back(pair.second);
+			}
+		}
+		for (std::vector<Object *>::iterator i = singleton_objects.begin(); i != singleton_objects.end(); i++) {
+			internal::gdextension_interface_object_free_instance_binding((*i)->_owner, internal::token);
+		}
+	}
 }
 
 } // namespace godot
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