{"ast_node_type":"other","tokens":[{"end":72,"kind":"keyword","start":0,"text":"//"}]}
    // We sometimes see MIR failures (notably predicate failures) due to
fn mirbug(tcx: TyCtxt<'_>, span: Span, msg: String) {
    // the fact that we check rvalue sized predicates here. So use `span_delayed_bug`