{"ast_node_type":"other","tokens":[{"end":72,"kind":"keyword","start":0,"text":"///"}]}
/// where the new vtable for an object will be derived from the old one.
/// The `old_info` argument is a bit odd. It is intended for use in an upcast,
fn unsized_info<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(