since approximately Isabelle/e0cd57aeb60c (~1 week): *** Malformed global fact "Misc_N2M.linorder_class.f1_t.n2m_t_ctor_fold_dict" *** Illegal fixed variable: "s1" *** At command "primrec" (line 164 of "~~/src/Benchmarks/Datatype_Benchmark/Misc_N2M.thy")