Mainly made that evarconv is able to solve "?n = (fun x => x) ?n" (sic).

Use two ways to solve it:
- added a whd_betaiota in solve_simple_eqn (since evarconv itself
  refuses beta to preserve the opportunities of first-order-matching
  expressions of the form "(fun x => P) t"; an advantage of this
  whd_betaiota is also that it may simplify K-redexes.
- also added a last-chance test in case of failing occur-check by
  trying to fully head-normalize (with delta) the right-hand-side
  (allows to solve for instance "?n = id ?n" where id is a constant
  (a bridled form of solve_refl that use fconv instead of evar_conv_x).
Incidentally improved a bit the rendering of the type of generalized
terms in pattern-matching by using whd_betaiota.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/trunk@13113 85f007b7-540e-0410-9357-904b9bb8a0f7

1 files changed, 1 insertions, 0 deletions

diff --git a/pretyping/cases.ml b/pretyping/cases.ml
index 64ad1801f..540db1c81 100644
--- a/pretyping/cases.ml
+++ b/pretyping/cases.ml
@@ -1024,6 +1024,7 @@ let rec generalize_problem names pb = function
   | [] -> pb
   | i::l ->
       let d = map_rel_declaration (lift i) (Environ.lookup_rel i pb.env) in
+      let d = on_pi3 (whd_betaiota !(pb.evdref)) d in (* for better rendering *)
       let pb' = generalize_problem names pb l in
       let tomatch = lift_tomatch_stack 1 pb'.tomatch in
       let tomatch = regeneralize_index_tomatch (i+1) tomatch in