Fix rustc_hidden_type_of_opaques for RPITITs with no default body

Author: compiler-errors

compiler/rustc_hir_analysis/src/collect/dump.rs

@@ -11,6 +11,15 @@ pub(crate) fn opaque_hidden_types(tcx: TyCtxt<'_>) {
     }
 
     for id in tcx.hir_crate_items(()).opaques() {
+        if let hir::OpaqueTyOrigin::FnReturn { parent: fn_def_id, .. }
+        | hir::OpaqueTyOrigin::AsyncFn { parent: fn_def_id, .. } =
+            tcx.hir().expect_opaque_ty(id).origin
+            && let hir::Node::TraitItem(trait_item) = tcx.hir_node_by_def_id(fn_def_id)
+            && let (_, hir::TraitFn::Required(..)) = trait_item.expect_fn()
+        {
+            continue;
+        }
+
         let ty = tcx.type_of(id).instantiate_identity();
         let span = tcx.def_span(id);
         tcx.dcx().emit_err(crate::errors::TypeOf { span, ty });