[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, 6 insertions, 3 deletions

diff --git a/plugins/ltac/extratactics.ml4 b/plugins/ltac/extratactics.ml4
index 10be8a842..6a758ed1f 100644
--- a/plugins/ltac/extratactics.ml4
+++ b/plugins/ltac/extratactics.ml4
@@ -253,6 +253,7 @@ let add_rewrite_hint ~poly bases ort t lcsr =
   let sigma = Evd.from_env env in
   let f ce =
     let c, ctx = Constrintern.interp_constr env sigma ce in
+    let c = EConstr.to_constr sigma c in
     let ctx =
       let ctx = UState.context_set ctx in
         if poly then ctx
@@ -554,6 +555,7 @@ let add_transitivity_lemma left lem =
   let env = Global.env () in
   let sigma = Evd.from_env env in
   let lem',ctx (*FIXME*) = Constrintern.interp_constr env sigma lem in
+  let lem' = EConstr.to_constr sigma lem' in
   add_anonymous_leaf (inTransitivity (left,lem'))
 
 (* Vernacular syntax *)
@@ -611,8 +613,10 @@ END
 
 VERNAC COMMAND EXTEND RetroknowledgeRegister CLASSIFIED AS SIDEFF
  | [ "Register" constr(c) "as" retroknowledge_field(f) "by" constr(b)] ->
-           [ let tc,ctx = Constrintern.interp_constr (Global.env ()) Evd.empty c in
-             let tb,ctx(*FIXME*) = Constrintern.interp_constr (Global.env ()) Evd.empty b in
+           [ let tc,_ctx = Constrintern.interp_constr (Global.env ()) Evd.empty c in
+             let tb,_ctx(*FIXME*) = Constrintern.interp_constr (Global.env ()) Evd.empty b in
+             let tc = EConstr.to_constr Evd.empty tc in
+             let tb = EConstr.to_constr Evd.empty tb in
              Global.register f tc tb ]
 END
 
@@ -705,7 +709,6 @@ let hResolve id c occ t =
           resolve_hole (subst_hole_with_term loc_begin c_raw t_hole)
   in
   let t_constr,ctx = resolve_hole (subst_var_with_hole occ id t_raw) in
-  let t_constr = EConstr.of_constr t_constr in
   let sigma = Evd.merge_universe_context sigma ctx in
   let t_constr_type = Retyping.get_type_of env sigma t_constr in
   Proofview.tclTHEN (Proofview.Unsafe.tclEVARS sigma)