Continuing r12485-12486 (cleaning around name generation)

- backtrack on incompatibility introduced in intro while trying to
  simplify the condition about when to restart the subscript of a name
  (the legacy says: find a new name from x0 if the name xN exists in
  the context but find a new name from xN+1 if the name xN does not
  exists in the context but is a global to avoid).
- made the names chosen by "intro" compliant with the ones printed in
  the goal and used for "intros until" (possible source of rare
  incompatibilities) [replaced the use of visibly_occur_id for
  printing the goal into a call to next_name_away_in_goal]
- also made the names internal to T in "T -> U" printed the same in
  the goal as they are while printing T after it is introducted in the
  hypotheses [non contravariant propagation of boolean isgoal in
  detype_binder]
- simplified a bit visibly_occur_id (the Rel and Var cases were useless as
  soon as the avoid list contained the current env); still this function is
  costly with polynomial time in the depth of binders
- see file output/Naming.v for examples

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@12549 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 11 insertions, 0 deletions

diff --git a/pretyping/termops.ml b/pretyping/termops.ml
index 4de4bde2cb..07ac5df215 100644
--- a/pretyping/termops.ml
+++ b/pretyping/termops.ml
@@ -523,6 +523,17 @@ let collect_metas c =
   in
   List.rev (collrec [] c)
 
+(* collects all visible var occurences (does not include indirect
+   dependencies of section variables via global references) *)
+
+let collect_visible_vars c =
+  let rec collrec acc c =
+    match kind_of_term c with
+    | Var id -> list_add_set id acc
+    | _      -> fold_constr collrec acc c
+  in
+  List.rev (collrec [] c)
+
 (* Tests whether [m] is a subterm of [t]:
    [m] is appropriately lifted through abstractions of [t] *)