3 files changed, 24 insertions, 2 deletions
diff --git a/core/extension/gdextension.cpp b/core/extension/gdextension.cpp
index 73526fae3e..67b55db3db 100644
--- a/core/extension/gdextension.cpp
+++ b/core/extension/gdextension.cpp
@@ -363,6 +363,10 @@ void GDExtension::_register_extension_class_integer_constant(GDExtensionClassLib
 }
 
 void GDExtension::_register_extension_class_property(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter) {
+	_register_extension_class_property_indexed(p_library, p_class_name, p_info, p_setter, p_getter, -1);
+}
+
+void GDExtension::_register_extension_class_property_indexed(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter, GDExtensionInt p_index) {
 	GDExtension *self = reinterpret_cast<GDExtension *>(p_library);
 
 	StringName class_name = *reinterpret_cast<const StringName *>(p_class_name);
@@ -371,10 +375,9 @@ void GDExtension::_register_extension_class_property(GDExtensionClassLibraryPtr
 	String property_name = *reinterpret_cast<const StringName *>(p_info->name);
 	ERR_FAIL_COND_MSG(!self->extension_classes.has(class_name), "Attempt to register extension class property '" + property_name + "' for unexisting class '" + class_name + "'.");
 
-	//Extension *extension = &self->extension_classes[class_name];
 	PropertyInfo pinfo(*p_info);
 
-	ClassDB::add_property(class_name, pinfo, setter, getter);
+	ClassDB::add_property(class_name, pinfo, setter, getter, p_index);
 }
 
 void GDExtension::_register_extension_class_property_group(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringPtr p_group_name, GDExtensionConstStringPtr p_prefix) {
@@ -542,6 +545,7 @@ void GDExtension::initialize_gdextensions() {
 	register_interface_function("classdb_register_extension_class_method", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_method);
 	register_interface_function("classdb_register_extension_class_integer_constant", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_integer_constant);
 	register_interface_function("classdb_register_extension_class_property", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_property);
+	register_interface_function("classdb_register_extension_class_property_indexed", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_property_indexed);
 	register_interface_function("classdb_register_extension_class_property_group", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_property_group);
 	register_interface_function("classdb_register_extension_class_property_subgroup", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_property_subgroup);
 	register_interface_function("classdb_register_extension_class_signal", (GDExtensionInterfaceFunctionPtr)&GDExtension::_register_extension_class_signal);
diff --git a/core/extension/gdextension.h b/core/extension/gdextension.h
index 77ec458d30..b935f8706f 100644
--- a/core/extension/gdextension.h
+++ b/core/extension/gdextension.h
@@ -54,6 +54,7 @@ class GDExtension : public Resource {
 	static void _register_extension_class_method(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionClassMethodInfo *p_method_info);
 	static void _register_extension_class_integer_constant(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_enum_name, GDExtensionConstStringNamePtr p_constant_name, GDExtensionInt p_constant_value, GDExtensionBool p_is_bitfield);
 	static void _register_extension_class_property(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter);
+	static void _register_extension_class_property_indexed(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter, GDExtensionInt p_index);
 	static void _register_extension_class_property_group(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_group_name, GDExtensionConstStringNamePtr p_prefix);
 	static void _register_extension_class_property_subgroup(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_subgroup_name, GDExtensionConstStringNamePtr p_prefix);
 	static void _register_extension_class_signal(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, GDExtensionConstStringNamePtr p_signal_name, const GDExtensionPropertyInfo *p_argument_info, GDExtensionInt p_argument_count);
diff --git a/core/extension/gdextension_interface.h b/core/extension/gdextension_interface.h
index 4d7bdf9502..43931cc8cd 100644
--- a/core/extension/gdextension_interface.h
+++ b/core/extension/gdextension_interface.h
@@ -2212,6 +2212,23 @@ typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassIntegerConstant)
 typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassProperty)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter);
 
 /**
+ * @name classdb_register_extension_class_property_indexed
+ * @since 4.2
+ *
+ * Registers an indexed property on an extension class in the ClassDB.
+ *
+ * Provided struct can be safely freed once the function returns.
+ *
+ * @param p_library A pointer the library received by the GDExtension's entry point function.
+ * @param p_class_name A pointer to a StringName with the class name.
+ * @param p_info A pointer to a GDExtensionPropertyInfo struct.
+ * @param p_setter A pointer to a StringName with the name of the setter method.
+ * @param p_getter A pointer to a StringName with the name of the getter method.
+ * @param p_index The index to pass as the first argument to the getter and setter methods.
+ */
+typedef void (*GDExtensionInterfaceClassdbRegisterExtensionClassPropertyIndexed)(GDExtensionClassLibraryPtr p_library, GDExtensionConstStringNamePtr p_class_name, const GDExtensionPropertyInfo *p_info, GDExtensionConstStringNamePtr p_setter, GDExtensionConstStringNamePtr p_getter, GDExtensionInt p_index);
+
+/**
  * @name classdb_register_extension_class_property_group
  * @since 4.1
  *