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[helm.git] / components / tactics / reductionTactics.ml

diff --git a/components/tactics/reductionTactics.ml b/components/tactics/reductionTactics.ml
index 3afef8eede4884141ab3c23aab3f79e73a842d61..9c39caa6f4cee2a4f03fbf505591398a65c24fda 100644 (file)
--- a/components/tactics/reductionTactics.ml
+++ b/components/tactics/reductionTactics.ml
@@ -135,7 +135,7 @@ exception NotConvertible
         reference variables that are local to the term that is going to be
         replaced. To fix this we should parse with_what in the context of the
         term(s) to be replaced. *)
-let change_tac ~pattern with_what  =
+let change_tac ?(with_cast=false) ~pattern with_what  =
  let change_tac ~pattern ~with_what (proof, goal) =
   let curi,metasenv,_subst,pbo,pty, attrs = proof in
   let (metano,context,ty) as conjecture = CicUtil.lookup_meta goal metasenv in
@@ -206,7 +206,19 @@ let change_tac ~pattern with_what  =
         | _ as t -> t)
       metasenv
   in
-  (curi,metasenv',_subst,pbo,pty, attrs), [metano]
+   let proof,goal = (curi,metasenv',_subst,pbo,pty, attrs), metano in
+    if with_cast then
+     let metano' = ProofEngineHelpers.new_meta_of_proof ~proof in
+     let (newproof,_) =
+       let irl= CicMkImplicit.identity_relocation_list_for_metavariable context'
+       in
+        ProofEngineHelpers.subst_meta_in_proof
+         proof metano
+          (Cic.Cast (Cic.Meta(metano',irl),ty')) [metano',context',ty']
+     in
+      newproof, [metano']
+    else
+     proof,[goal]
   in
     mk_tactic (change_tac ~pattern ~with_what)