improved check in delift for flexible lc entries.

[helm.git] / helm / software / components / ng_refiner / nCicMetaSubst.ml

diff --git a/helm/software/components/ng_refiner/nCicMetaSubst.ml b/helm/software/components/ng_refiner/nCicMetaSubst.ml
index 9cc6ac67c755c16e4208413f1cd7565859c64557..60abe85c37c08879ea80d01ededa27c158d0192f 100644 (file)
--- a/helm/software/components/ng_refiner/nCicMetaSubst.ml
+++ b/helm/software/components/ng_refiner/nCicMetaSubst.ml
@@ -206,12 +206,29 @@ and restrict metasenv subst i restrictions =
     | NCicUtils.Meta_not_found _ -> assert false
 ;;
 
-let rec flexible_arg subst = function 
+let rec flexible_arg context subst = function 
   | NCic.Meta (i,_) | NCic.Appl (NCic.Meta (i,_) :: _)-> 
       (try 
         let _,_,t,_ = List.assoc i subst in
-        flexible_arg subst t
+        flexible_arg context subst t
       with Not_found -> true)
+   (* this is a cheap whd, it only performs zeta-reduction.
+    * 
+    * it works when the **omissis** disambiguation algorithm
+    * is run on `let x := K a b in t`, K is substituted for a 
+    * ? and thus in t metavariables have a flexible Rel
+    *)
+  | NCic.Rel i ->
+      (try
+         match List.nth context (i-1)
+         with 
+         | _,NCic.Def (bo,_) ->
+               flexible_arg context subst
+                 (NCicSubstitution.lift i bo)
+         | _ -> false
+      with 
+      | Failure _ -> assert false
+      | Invalid_argument _ -> assert false)
   | _ -> false
 ;;
 
@@ -254,33 +271,26 @@ let delift ~unify metasenv subst context n l t =
     in
     try aux () () t; false with Found -> true
   in
-  let unify_list ~alpha in_scope = 
+  let unify_list in_scope = 
     match l with
     | _, NCic.Irl _ -> fun _ _ _ _ _ -> None
     | shift, NCic.Ctx l -> fun metasenv subst context k t ->
-       if flexible_arg subst t || contains_in_scope subst t then None else
-         let lb = List.map (fun t -> t, flexible_arg subst t) l in
+       if flexible_arg context subst t || contains_in_scope subst t then None else
+         let lb = List.map (fun t -> t, flexible_arg context subst t) l in
          HExtlib.list_findopt
           (fun (li,flexible) i ->
             if flexible || i < in_scope then None else
              let li = NCicSubstitution.lift (k+shift) li in
-              if alpha then
-               if NCicReduction.alpha_eq metasenv subst context li t then
-                Some ((metasenv,subst), NCic.Rel (i+1+k))
-               else
-                None
-              else
-               match unify metasenv subst context li t with
-               | Some (metasenv,subst) -> 
-                   Some ((metasenv, subst), NCic.Rel (i+1+k))
-               | None -> None)
+             match unify metasenv subst context li t with
+             | Some (metasenv,subst) -> 
+                 Some ((metasenv, subst), NCic.Rel (i+1+k))
+             | None -> None)
           lb
   in
   let rec aux (context,k,in_scope) (metasenv, subst as ms) t = 
-   match unify_list ~alpha:true in_scope metasenv subst context k t with
+   match unify_list in_scope metasenv subst context k t with
    | Some x -> x
    | None -> 
-   try
     match t with 
     | NCic.Rel n as t when n <= k -> ms, t
     | NCic.Rel n -> 
@@ -411,10 +421,6 @@ let delift ~unify metasenv subst context n l t =
     | t -> 
         NCicUntrusted.map_term_fold_a 
           (fun e (c,k,s) -> (e::c,k+1,s)) (context,k,in_scope) aux ms t
-   with NotInTheList ->
-    match unify_list ~alpha:false in_scope metasenv subst context k t with
-    | Some x -> x
-    | None -> raise NotInTheList
   in
    try aux (context,0,0) (metasenv,subst) t
    with NotInTheList ->