src/HOL/Tools/BNF/bnf_gfp_grec_sugar_tactics.ML

 fun mk_cong_intro_ctr_or_friend_tac ctxt ctr_or_friend_def extra_simps cong_alg_intro =
   HEADGOAL (REPEAT_DETERM_N 2 o subst_tac ctxt NONE [ctr_or_friend_def] THEN'
     rtac ctxt cong_alg_intro) THEN
   unfold_thms_tac ctxt (extra_simps @ sumprod_thms_rel @
     @{thms vimage2p_def prod.rel_eq sum.rel_eq}) THEN
-  REPEAT_DETERM (HEADGOAL (etac ctxt subst ORELSE' rtac ctxt conjI ORELSE' assume_tac ctxt ORELSE'
-    rtac ctxt refl));
+  REPEAT_DETERM (HEADGOAL (rtac ctxt conjI ORELSE' assume_tac ctxt ORELSE' rtac ctxt refl ORELSE'
+    etac ctxt subst));
 
 val shared_simps =
   @{thms map_prod_simp map_sum.simps sum.case prod.case_eq_if split_beta' prod.sel
       sum.disc(1)[THEN eq_True[THEN iffD2]] sum.disc(2)[THEN eq_False[THEN iffD2]] sum.sel
       isl_map_sum map_sum_sel if_True if_False if_True_False Let_def[abs_def] o_def[abs_def] id_def