X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=blobdiff_plain;f=helm%2Fsoftware%2Fcomponents%2Ftactics%2FequalityTactics.ml;h=16aa6d3b2d5925a10b1ab3bf7e47583885365c2f;hb=04dc7b17e463fa9c75ac91e1df88bf37ed009914;hp=82c339ae2b3d13381b6f1fee090eb1721f190fb9;hpb=36842ee77114d2fa896d7ffd2333c07cff22b053;p=helm.git

diff --git a/helm/software/components/tactics/equalityTactics.ml b/helm/software/components/tactics/equalityTactics.ml
index 82c339ae2..16aa6d3b2 100644
--- a/helm/software/components/tactics/equalityTactics.ml
+++ b/helm/software/components/tactics/equalityTactics.ml
@@ -46,8 +46,6 @@ let rec rewrite_tac ~direction ~pattern:(wanted,hyps_pat,concl_pat) equality =
   let proof,goal = status in
   let curi, metasenv, _subst, pbo, pty, attrs = proof in
   let (metano,context,gty) = CicUtil.lookup_meta goal metasenv in
-  let gsort,_ =
-   CicTypeChecker.type_of_aux' metasenv context gty CicUniv.oblivion_ugraph in
   match hyps_pat with
      he::(_::_ as tl) ->
        PET.apply_tactic
@@ -89,6 +87,8 @@ let rec rewrite_tac ~direction ~pattern:(wanted,hyps_pat,concl_pat) equality =
          Some pat,gty
     | _::_ -> assert false
   in
+  let gsort,_ =
+   CicTypeChecker.type_of_aux' metasenv context gty CicUniv.oblivion_ugraph in
   let if_right_to_left do_not_change a b = 
     match direction with
     | `RightToLeft -> if do_not_change then a else b
@@ -198,8 +198,8 @@ let rec rewrite_tac ~direction ~pattern:(wanted,hyps_pat,concl_pat) equality =
     in
      (proof',goals)
   with (* FG: this should be PET.Fail _ *)
-     TC.TypeCheckerFailure _ -> 
-      let msg = lazy "rewrite: nothing to rewrite" in
+     TC.TypeCheckerFailure m -> 
+      let msg = lazy ("rewrite: "^ Lazy.force m) in
       raise (PET.Fail msg)
  in    
   PET.mk_tactic _rewrite_tac