[econstr] Continue consolidation of EConstr API under `interp`.

This commit was motivated by true spurious conversions arising in my
`to_constr` debug branch.

The changes here need careful review as the tradeoffs are subtle and
still a lot of clean up remains to be done in `vernac/*`.

We have opted for penalize [minimally] the few users coming from true
`Constr`-land, but I am sure we can tweak code in a much better way.

In particular, it is not clear if internalization should take an
`evar_map` even in the cases where it is not triggered, see the
changes under `plugins` for a good example.

Also, the new return type of `Pretyping.understand` should undergo
careful review.

We don't touch `Impargs` as it is not clear how to proceed, however,
the current type of `compute_implicits_gen` looks very suspicious as
it is called often with free evars.

Some TODOs are:

- impargs was calling whd_all, the Econstr equivalent can be either
  + Reductionops.whd_all [which does refolding and no sharing]
  + Reductionops.clos_whd_flags with all as a flag.

1 files changed, 1 insertions, 1 deletions

diff --git a/vernac/classes.ml b/vernac/classes.ml
index 695be74bb..93af94ad6 100644
--- a/vernac/classes.ml
+++ b/vernac/classes.ml
@@ -52,7 +52,7 @@ let _ =
        let open Vernacexpr in
        { info with hint_pattern =
 		   Option.map
-		     (Constrintern.intern_constr_pattern (Global.env()))
+                     (Constrintern.intern_constr_pattern (Global.env()) Evd.(from_env Global.(env())))
 		     info.hint_pattern } in
      Flags.silently (fun () ->
 	Hints.add_hints local [typeclasses_db]