From c4ca5dc437886c8a2cf0e34a5fbb17cdb1f4353b Mon Sep 17 00:00:00 2001
From: Claudio Sacerdoti Coen <claudio.sacerdoticoen@unibo.it>
Date: Tue, 12 Sep 2006 15:57:44 +0000
Subject: [PATCH] Bug fixed in the guarded_by_descructors function: in some
 cases the context was missing the left arguments! This is the first bug found
 in the kernel after quite a long time.

---
 .../cic_proof_checking/cicTypeChecker.ml      | 26 +++++++++++++------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/components/cic_proof_checking/cicTypeChecker.ml b/components/cic_proof_checking/cicTypeChecker.ml
index c0e90a5c6..81b33b0d1 100644
--- a/components/cic_proof_checking/cicTypeChecker.ml
+++ b/components/cic_proof_checking/cicTypeChecker.ml
@@ -952,7 +952,7 @@ and guarded_by_destructors ~subst context n nn kl x safes =
    | C.MutCase (uri,i,outtype,term,pl) ->
       (match CicReduction.whd ~subst context term with
           C.Rel m when List.mem m safes || m = x ->
-           let (tys,len,isinductive,paramsno,cl) =
+           let (lefts_and_tys,len,isinductive,paramsno,cl) =
 	    let o,_ = CicEnvironment.get_obj CicUniv.empty_ugraph uri in
             match o with
                C.InductiveDefinition (tl,_,paramsno,_) ->
@@ -968,9 +968,14 @@ and guarded_by_destructors ~subst context n nn kl x safes =
                       let debrujinedty = debrujin_constructor uri len ty in
                        (id, snd (split_prods ~subst tys paramsno ty),
                         snd (split_prods ~subst tys paramsno debrujinedty)
-                       )) cl
+                       )) cl in
+                   let lefts =
+                    match tl with
+                       [] -> assert false
+                     | (_,_,ty,_)::_ ->
+                        fst (split_prods ~subst [] paramsno ty)
                    in
-                    (tys,len,isinductive,paramsno,cl')
+                    (tys@lefts,len,isinductive,paramsno,cl')
              | _ ->
                 raise (TypeCheckerFailure
                   (lazy ("Unknown mutual inductive definition:" ^
@@ -996,7 +1001,7 @@ and guarded_by_destructors ~subst context n nn kl x safes =
               (*CSC: manca ??? il controllo sul tipo di term? *)
               List.fold_right
                (fun (p,(_,c,brujinedc)) i ->
-                 let rl' = recursive_args tys 0 len brujinedc in
+                 let rl' = recursive_args lefts_and_tys 0 len brujinedc in
                   let (e,safes',n',nn',x',context') =
                    get_new_safes ~subst context p c rl' safes n nn x
                   in
@@ -1004,7 +1009,7 @@ and guarded_by_destructors ~subst context n nn kl x safes =
                    guarded_by_destructors ~subst context' n' nn' kl x' safes' e
                ) pl_and_cl true
         | C.Appl ((C.Rel m)::tl) when List.mem m safes || m = x ->
-           let (tys,len,isinductive,paramsno,cl) =
+           let (lefts_and_tys,len,isinductive,paramsno,cl) =
 	    let o,_ = CicEnvironment.get_obj CicUniv.empty_ugraph uri in
             match o with
                C.InductiveDefinition (tl,_,paramsno,_) ->
@@ -1016,9 +1021,14 @@ and guarded_by_destructors ~subst context n nn kl x safes =
                   let cl' =
                    List.map
                     (fun (id,ty) ->
-                      (id, snd (split_prods ~subst tys paramsno ty))) cl
+                      (id, snd (split_prods ~subst tys paramsno ty))) cl in
+                  let lefts =
+                   match tl with
+                      [] -> assert false
+                    | (_,_,ty,_)::_ ->
+                       fst (split_prods ~subst [] paramsno ty)
                   in
-                   (tys,List.length tl,isinductive,paramsno,cl')
+                   (tys@lefts,List.length tl,isinductive,paramsno,cl')
              | _ ->
                 raise (TypeCheckerFailure
                   (lazy ("Unknown mutual inductive definition:" ^
@@ -1050,7 +1060,7 @@ and guarded_by_destructors ~subst context n nn kl x safes =
                (fun (p,(_,c)) i ->
                  let rl' =
                   let debrujinedte = debrujin_constructor uri len c in
-                   recursive_args tys 0 len debrujinedte
+                   recursive_args lefts_and_tys 0 len debrujinedte
                  in
                   let (e, safes',n',nn',x',context') =
                    get_new_safes ~subst context p c rl' safes n nn x
-- 
2.39.2