yeet upcast_trait_def_id from ImplSourceObjectData

compiler/rustc_trait_selection/src/traits/select/confirmation.rs

@@ -651,11 +651,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
             (unnormalized_upcast_trait_ref, ty::Binder::dummy(object_trait_ref)),
         );
 
-        Ok(ImplSourceObjectData {
-            upcast_trait_def_id: upcast_trait_ref.def_id(),
-            vtable_base,
-            nested,
-        })
+        Ok(ImplSourceObjectData { vtable_base, nested })
     }
 
     fn confirm_fn_pointer_candidate(

compiler/rustc_trait_selection/src/traits/util.rs

@@ -248,7 +248,7 @@ pub fn get_vtable_index_of_object_method<'tcx, N>(
 ) -> Option<usize> {
     // Count number of methods preceding the one we are selecting and
     // add them to the total offset.
-    tcx.own_existential_vtable_entries(object.upcast_trait_def_id)
+    tcx.own_existential_vtable_entries(tcx.parent(method_def_id))
         .iter()
         .copied()
         .position(|def_id| def_id == method_def_id)