File "pr6293_bad.ml", line 10, characters 18-37:
10 | let f (module M : S with type t = int) = { M.a = 0 };;
                       ^^^^^^^^^^^^^^^^^^^
Error: In this "with" constraint, the new definition of "t"
       does not match its original definition in the constrained signature:
       Type declarations do not match:
         type t
       is not included in
         type t = { a : int; b : int; }
       The first is abstract, but the second is a record.
       File "pr6293_bad.ml", line 9, characters 20-50: Expected declaration
       File "pr6293_bad.ml", line 10, characters 18-37: Actual declaration