aces it.

** Type Clashes
  In agreement with POSIX and with other Yaccs, leaving a default
  action is valid when $$ is untyped, and $1 typed:

        untyped: ... typed;

  but the converse remains an error:

        typed: ... untyped;

** Values of midrule actions
  The following code:

        foo: { ... } { $$ = $1; } ...

  was incorrectly rejected: $1 is defined in the second midrule
  action, and is equal to the $$ of the first midrule action.