src/Pure/Tools/build.ML

 fun no_document options =
   (case Options.string options "document" of "" => true | "false" => true | _ => false);
 
 fun use_theories last_timing options =
   Thy_Info.use_theories {last_timing = last_timing, master_dir = Path.current}
-    |> Unsynchronized.setmp Proofterm.proofs (Options.int options "proofs")
     |> Unsynchronized.setmp print_mode
         (space_explode "," (Options.string options "print_mode") @ print_mode_value ())
     |> Unsynchronized.setmp Goal.parallel_proofs (Options.int options "parallel_proofs")
     |> Unsynchronized.setmp Multithreading.trace (Options.int options "threads_trace")
     |> Unsynchronized.setmp Multithreading.max_threads (Options.int options "threads")