{"ast_node_type":"other","tokens":[{"end":70,"kind":"keyword","start":0,"text":"ForwardDeclaredGenericParam(Symbol,"}]}
    ForwardDeclaredGenericParam(Symbol, ForwardGenericParamBanReason),
    /// Error E0128: generic parameters with a default cannot use forward-declared identifiers.
    // FIXME(generic_const_parameter_types): This should give custom output specifying it's only