src/HOL/Fun.thy

     Simplifier.simproc (Theory.sign_of (the_context ()))
       "fun_upd2" ["f(v := w, x := y)"]
       (fn sg => fn ss => fn t =>
         case find_double t of (T, NONE) => NONE
         | (T, SOME rhs) =>
-            SOME (Tactic.prove sg [] [] (Term.equals T $ t $ rhs) (K (fun_upd_prover ss))))
+            SOME (Goal.prove sg [] [] (Term.equals T $ t $ rhs) (K (fun_upd_prover ss))))
 end;
 Addsimprocs[fun_upd2_simproc];
 
 val expand_fun_eq = thm "expand_fun_eq";
 val apply_inverse = thm "apply_inverse";