X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Fng_tactics%2FnTactics.ml;h=f5ae3a721e4880a955d4be5463252cf4423e2a36;hb=12f96bd48b460d06f9858a334ee7c52d6831712f;hp=10fa168d492517123eff7b4b18861cb9827cfa47;hpb=2dd6e8f11fa3ac2995f326ecb742d9b4e8948fce;p=helm.git

diff --git a/helm/software/components/ng_tactics/nTactics.ml b/helm/software/components/ng_tactics/nTactics.ml
index 10fa168d4..f5ae3a721 100644
--- a/helm/software/components/ng_tactics/nTactics.ml
+++ b/helm/software/components/ng_tactics/nTactics.ml
@@ -46,13 +46,14 @@ let dot_tac status =
    status#set_stack gstatus
 ;;
 
-let branch_tac status =
+let branch_tac ?(force=false) status =
   let gstatus = 
     match status#stack with
     | [] -> assert false
     | (g, t, k, tag) :: s ->
           match init_pos g with (* TODO *)
-          | [] | [ _ ] -> fail (lazy "too few goals to branch")
+          | [] -> fail (lazy "empty goals")
+	  | [_] when (not force) -> fail (lazy "too few goals to branch")
           | loc :: loc_tl ->
                ([ loc ], [], [], `BranchTag) :: (loc_tl, t, k, tag) :: s
   in
@@ -644,7 +645,7 @@ let assert_tac seqs status =
        | [seq] -> assert0_tac seq
        | _ ->
          block_tac
-          (branch_tac::
+          ((branch_tac ~force:false)::
           HExtlib.list_concat ~sep:[shift_tac]
             (List.map (fun seq -> [assert0_tac seq]) seqs)@
           [merge_tac])