Use an enum to pass the index value for interfaces/protos.

components/script/dom/bindings/codegen/CodegenRust.py

@@ -3490,11 +3490,12 @@ class CGGetPerInterfaceObject(CGAbstractMethod):
         CGAbstractMethod.__init__(self, descriptor, name,
                                   'void', args, pub=pub)
         self.id = idPrefix + "::" + MakeNativeName(self.descriptor.name)
+        self.variant = self.id.split('::')[-2]
 
     def definition_body(self):
         return CGGeneric("""
-        get_per_interface_object_handle(cx, global, %s as usize, CreateInterfaceObjects, rval)
+        get_per_interface_object_handle(cx, global, ProtoOrIfaceIndex::%s(%s), CreateInterfaceObjects, rval)
-        """ % self.id)
+        """ % (self.variant, self.id))
 
 
 class CGGetProtoObjectMethod(CGGetPerInterfaceObject):
@@ -3647,14 +3648,15 @@ class CGDefineDOMInterfaceMethod(CGAbstractMethod):
         else:
             idPrefix = "PrototypeList::ID"
         self.id = idPrefix + "::" + MakeNativeName(self.descriptor.name)
+        self.variant = self.id.split('::')[-2]
 
     def define(self):
         return CGAbstractMethod.define(self)
 
     def definition_body(self):
         return CGGeneric("""
-        define_dom_interface(cx, global, %s as usize, CreateInterfaceObjects, ConstructorEnabled)
+        define_dom_interface(cx, global, ProtoOrIfaceIndex::%s(%s), CreateInterfaceObjects, ConstructorEnabled)
-        """ % self.id)
+        """ % (self.variant, self.id))
 
 
 def needCx(returnType, arguments, considerTypes):
@@ -6425,17 +6427,18 @@ def generate_imports(config, cgthings, descriptors, callbacks=None, dictionaries
         'crate::dom::bindings::interface::ConstructorClassHook',
         'crate::dom::bindings::interface::InterfaceConstructorBehavior',
         'crate::dom::bindings::interface::NonCallbackInterfaceObjectClass',
+        'crate::dom::bindings::interface::ProtoOrIfaceIndex',
         'crate::dom::bindings::interface::create_global_object',
         'crate::dom::bindings::interface::create_callback_interface_object',
         'crate::dom::bindings::interface::create_interface_prototype_object',
         'crate::dom::bindings::interface::create_named_constructors',
         'crate::dom::bindings::interface::create_noncallback_interface_object',
+        'crate::dom::bindings::interface::define_dom_interface',
         'crate::dom::bindings::interface::define_guarded_constants',
         'crate::dom::bindings::interface::define_guarded_methods',
         'crate::dom::bindings::interface::define_guarded_properties',
         'crate::dom::bindings::interface::is_exposed_in',
         'crate::dom::bindings::interface::get_per_interface_object_handle',
-        'crate::dom::bindings::interface::define_dom_interface',
         'crate::dom::bindings::htmlconstructor::pop_current_element_queue',
         'crate::dom::bindings::htmlconstructor::push_new_element_queue',
         'crate::dom::bindings::iterable::Iterable',

components/script/dom/bindings/interface.rs

@@ -537,10 +537,24 @@ unsafe extern "C" fn non_new_constructor(
     false
 }
 
+pub enum ProtoOrIfaceIndex {
+    ID(PrototypeList::ID),
+    Constructor(PrototypeList::Constructor),
+}
+
+impl Into<usize> for ProtoOrIfaceIndex {
+    fn into(self) -> usize {
+        match self {
+            ProtoOrIfaceIndex::ID(id) => id as usize,
+            ProtoOrIfaceIndex::Constructor(constructor) => constructor as usize,
+        }
+    }
+}
+
 pub fn get_per_interface_object_handle(
     cx: SafeJSContext,
     global: HandleObject,
-    id: usize,
+    id: ProtoOrIfaceIndex,
     creator: unsafe fn(SafeJSContext, HandleObject, *mut ProtoOrIfaceArray),
     mut rval: MutableHandleObject,
 ) {
@@ -549,13 +563,14 @@ pub fn get_per_interface_object_handle(
 
         /* Check to see whether the interface objects are already installed */
         let proto_or_iface_array = get_proto_or_iface_array(global.get());
-        rval.set((*proto_or_iface_array)[id]);
+        let index: usize = id.into();
+        rval.set((*proto_or_iface_array)[index]);
         if !rval.get().is_null() {
             return;
         }
 
         creator(cx, global, proto_or_iface_array);
-        rval.set((*proto_or_iface_array)[id]);
+        rval.set((*proto_or_iface_array)[index]);
         assert!(!rval.get().is_null());
     }
 }
@@ -563,7 +578,7 @@ pub fn get_per_interface_object_handle(
 pub fn define_dom_interface(
     cx: SafeJSContext,
     global: HandleObject,
-    id: usize,
+    id: ProtoOrIfaceIndex,
     creator: unsafe fn(SafeJSContext, HandleObject, *mut ProtoOrIfaceArray),
     enabled: fn(SafeJSContext, HandleObject) -> bool,
 ) {