[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/plugins/setoid_ring/newring.ml b/plugins/setoid_ring/newring.ml
index 125afb1a0..0f0dbfff3 100644
--- a/plugins/setoid_ring/newring.ml
+++ b/plugins/setoid_ring/newring.ml
@@ -148,7 +148,7 @@ let ic c =
 let ic_unsafe c = (*FIXME remove *)
   let env = Global.env() in
   let sigma = Evd.from_env env in
-    EConstr.of_constr (fst (Constrintern.interp_constr env sigma c))
+  fst (Constrintern.interp_constr env sigma c)
 
 let decl_constant na univs c =
   let open Constr in