{"ast_node_type":"other","tokens":[{"end":54,"kind":"keyword","start":0,"text":"ForwardDeclaredSelf(ForwardGenericParamBanReason),"}]}
    ForwardDeclaredSelf(ForwardGenericParamBanReason),
    /// Error E0735: generic parameters with a default cannot use `Self`
    /// Error E0767: use of unreachable label