The AssocOpaqueTy HIR node is not actually needed to differentiate from other hir nodes that were fed

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -196,7 +196,7 @@ fn check_well_formed(tcx: TyCtxt<'_>, def_id: hir::OwnerId) -> Result<(), ErrorG
         hir::OwnerNode::TraitItem(item) => check_trait_item(tcx, item),
         hir::OwnerNode::ImplItem(item) => check_impl_item(tcx, item),
         hir::OwnerNode::ForeignItem(item) => check_foreign_item(tcx, item),
-        hir::OwnerNode::AssocOpaqueTy(..) => unreachable!(),
+        hir::OwnerNode::Synthetic => unreachable!(),
     };
 
     if let Some(generics) = node.generics() {