{"ast_node_type":"other","tokens":[{"end":11,"kind":"keyword","start":0,"text":"Stable,"}]}
    Stable,
    /// The 1.0 rules (either types fail to unify, or where clauses are not implemented for crate-local types)
    /// Feature-gated test: Stable, *or* there is an explicit negative impl that rules out one of the where-clauses.