{"ast_node_type":"other","tokens":[{"end":36,"kind":"keyword","start":0,"text":"//"}]}
    // env_ty = `Pin<&mut proxy_ty>`
    let ret_ty = Ty::new_adt(tcx, poll_adt_ref, tcx.mk_args(&[tcx.types.unit.into()]));
    let pin_adt_ref = tcx.adt_def(tcx.require_lang_item(LangItem::Pin, span));