Fixed bug #2135 (second-order unification was raising cryptic message)

- made the example work (a call to whd_meta was missing)
- replaced the internal error messages of w_unify_to_subterm_list into
  user-understandable messages
- incidentally fixed the meaning of whd_meta (which now takes an evd)
  and meta_name (which now does what it means and do not treat differently
  the instantiated metas)

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@13122 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 10 insertions, 0 deletions

diff --git a/pretyping/pretype_errors.ml b/pretyping/pretype_errors.ml
index 5b829e5bf..e92ab3206 100644
--- a/pretyping/pretype_errors.ml
+++ b/pretyping/pretype_errors.ml
@@ -32,6 +32,8 @@ type pretype_error =
   | CannotGeneralize of constr
   | NoOccurrenceFound of constr * identifier option
   | CannotFindWellTypedAbstraction of constr * constr list
+  | AbstractionOverMeta of name * name
+  | NonLinearUnification of name * constr
   (* Pretyping *)
   | VarNotFound of identifier
   | UnexpectedType of constr * constr
@@ -174,6 +176,14 @@ let error_cannot_coerce env sigma (m,n) =
 let error_cannot_find_well_typed_abstraction env sigma p l =
   raise (PretypeError (env_ise sigma env,CannotFindWellTypedAbstraction (p,l)))
 
+let error_abstraction_over_meta env sigma hdmeta metaarg =
+  let m = Evd.meta_name sigma hdmeta and n = Evd.meta_name sigma metaarg in
+  raise (PretypeError (env_ise sigma env,AbstractionOverMeta (m,n)))
+
+let error_non_linear_unification env sigma hdmeta t =
+  let m = Evd.meta_name sigma hdmeta in
+  raise (PretypeError (env_ise sigma env,NonLinearUnification (m,t)))
+
 (*s Ml Case errors *)
 
 let error_cant_find_case_type_loc loc env sigma expr =