Fix bug #5501: Universe polymorphism breaks proof involving auto.

A universe substitution was lacking as the normalized evar map was dropped.

2 files changed, 23 insertions, 5 deletions

diff --git a/tactics/hints.ml b/tactics/hints.ml
index bcc068d3d..50b811edb 100644
--- a/tactics/hints.ml
+++ b/tactics/hints.ml
@@ -1238,18 +1238,15 @@ let prepare_hint check (poly,local) env init (sigma,c) =
   (* We re-abstract over uninstantiated evars and universes.
      It is actually a bit stupid to generalize over evars since the first
      thing make_resolves will do is to re-instantiate the products *)
-  let sigma, subst = Evd.nf_univ_variables sigma in
+  let sigma, _ = Evd.nf_univ_variables sigma in
   let c = Evarutil.nf_evar sigma c in
-  let c = EConstr.Unsafe.to_constr c in
-  let c = CVars.subst_univs_constr subst c in
-  let c = EConstr.of_constr c in
   let c = drop_extra_implicit_args sigma c in
   let vars = ref (collect_vars sigma c) in
   let subst = ref [] in
   let rec find_next_evar c = match EConstr.kind sigma c with
     | Evar (evk,args as ev) ->
       (* We skip the test whether args is the identity or not *)
-      let t = existential_type sigma ev in
+      let t = Evarutil.nf_evar sigma (existential_type sigma ev) in
       let t = List.fold_right (fun (e,id) c -> replace_term sigma e id c) !subst t in
       if not (closed0 sigma c) then
 	error "Hints with holes dependent on a bound variable not supported.";
diff --git a/test-suite/bugs/closed/5501.v b/test-suite/bugs/closed/5501.v
new file mode 100644
index 000000000..24739a365
--- /dev/null
+++ b/test-suite/bugs/closed/5501.v
@@ -0,0 +1,21 @@
+Set Universe Polymorphism.
+
+Record Pred@{A} :=
+  { car :> Type@{A}
+  ; P : car -> Prop
+  }.
+
+Class All@{A} (A : Pred@{A}) : Type :=
+  { proof : forall (a : A), P A a
+  }.
+
+Record Pred_All@{A} : Type :=
+  { P' :> Pred@{A}
+  ; P'_All : All P'
+  }.
+
+Global Instance Pred_All_instance (A : Pred_All) : All A := P'_All A.
+
+Definition Pred_All_proof {A : Pred_All} (a : A) : P A a.
+Proof.
+solve[auto using proof].