File "t04bad.ml", line 10, characters 0-73:
10 | module rec A : sig type t = int * A.t end = struct type t = int * A.t end;;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: The type abbreviation "A.t" is cyclic:
         "int * A.t" contains "A.t",
         "A.t" = "int * A.t",
         "int * A.t" contains "A.t"