Fixing bug #2193: computation of dependencies in the "match" return

predicate was incomplete.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@12615 85f007b7-540e-0410-9357-904b9bb8a0f7

2 files changed, 36 insertions, 2 deletions

diff --git a/pretyping/cases.ml b/pretyping/cases.ml
index 177389c98a..f68bf10c4b 100644
--- a/pretyping/cases.ml
+++ b/pretyping/cases.ml
@@ -835,7 +835,7 @@ let rec map_predicate f k ccl = function
   | Abstract _ :: rest ->
       map_predicate f (k+1) ccl rest
 
-let noccurn_predicate = map_predicate noccurn
+let noccur_predicate_between n = map_predicate (noccur_between n)
 
 let liftn_predicate n = map_predicate (liftn n)
 
@@ -1110,13 +1110,16 @@ let build_branch current deps (realnames,dep) pb arsign eqns const_info =
   (* into  "Gamma; typs; curalias |- tms" *)
   let tomatch = lift_tomatch_stack const_info.cs_nargs pb.tomatch in
 
+  let pred_is_not_dep =
+    noccur_predicate_between 1 (List.length realnames + 1) pb.pred tomatch in
+
   let typs'' =
     list_map2_i
       (fun i (na,t) deps ->
 	let dep = match dep with
 	  | Name _ as na',k -> (if na <> Anonymous then na else na'),k
 	  | Anonymous,KnownNotDep ->
-	      if deps = [] && noccurn_predicate 1 pb.pred tomatch then
+	      if deps = [] && pred_is_not_dep then
 		(Anonymous,KnownNotDep)
 	      else
 		(force_name na,KnownDep)
diff --git a/test-suite/bugs/closed/shouldsucceed/2193.v b/test-suite/bugs/closed/shouldsucceed/2193.v
new file mode 100644
index 0000000000..fe2588676d
--- /dev/null
+++ b/test-suite/bugs/closed/shouldsucceed/2193.v
@@ -0,0 +1,31 @@
+(* Computation of dependencies in the "match" return predicate was incomplete *)
+(* Submitted by R. O'Connor, Nov 2009 *)
+
+Inductive Symbol : Set :=
+ | VAR : Symbol.
+
+Inductive SExpression :=
+ | atomic : Symbol -> SExpression.
+
+Inductive ProperExpr : SExpression -> SExpression -> Type :=
+ | pe_3 : forall (x : Symbol) (alpha : SExpression),
+    ProperExpr alpha (atomic VAR) ->
+    ProperExpr (atomic x) alpha.
+
+Definition A (P : forall s : SExpression, Type)
+ (x alpha alpha1 : SExpression)
+ (t : ProperExpr (x) alpha1) : option (x = atomic VAR) :=
+ match t as pe in ProperExpr a b return option (a = atomic VAR) with
+ | pe_3 x0 alpha3 tye' => 
+      (fun (x:Symbol) (alpha : SExpression) => @None (atomic x = atomic VAR))
+       x0 alpha3
+ end.
+
+Definition B (P : forall s : SExpression, Type)
+ (x alpha alpha1 : SExpression)
+ (t : ProperExpr (x) alpha1) : option (x = atomic VAR) :=
+ match t as pe in ProperExpr a b return option (a = atomic VAR) with
+ | pe_3 x0 alpha3 tye' => 
+      (fun (x:Symbol) (alpha : SExpression) (t:ProperExpr alpha (atomic VAR)) => @None (atomic x = atomic VAR))
+       x0 alpha3 tye'
+ end.