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diff --git a/test-suite/bugs/opened/4781.v b/test-suite/bugs/opened/4781.v
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+++ b/test-suite/bugs/opened/4781.v
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+Ltac force_clear :=
+  clear;
+  repeat match goal with
+         | [ H : _ |- _ ] => clear H
+         | [ H := _ |- _ ] => clearbody H
+         end.
+
+Class abstract_term {T} (x : T) := by_abstract_term : T.
+Hint Extern 0 (@abstract_term ?T ?x) => force_clear; change T; abstract (exact x) : typeclass_instances.
+
+Goal True.
+(* These work: *)
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  pose x.
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := (eval cbv iota in (let v : T := x in v)) in
+  pose x.
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := match constr:(Set) with ?y => constr:(y) end in
+  pose x.
+(* This fails with an error: *)
+  Fail let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := match constr:(x) with ?y => constr:(y) end in
+  pose x. (* The command has indeed failed with message:
+Error: Variable y should be bound to a term. *)
+(* And the rest fail with Anomaly: Uncaught exception Not_found. Please report. *)
+  Fail let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := match constr:(x) with ?y => y end in
+  pose x.
+  Fail let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := (eval cbv iota in x) in
+  pose x.
+  Fail let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let x := type of x in
+  pose x. (* should succeed *)
+  Fail let term := constr:(I) in
+  let T := type of term in
+  let x := constr:(_ : abstract_term term) in
+  let x := type of x in
+  pose x. (* should succeed *)
+
+(*Apparently what [cbv iota] doesn't see can't hurt it, and [pose] is perfectly happy with abstracted lemmas only some of the time.
+
+Even stranger, consider:*)
+  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let y := (eval cbv iota in (let v : T := x in v)) in
+  pose y;
+    let x' := fresh "x'" in
+    pose x as x'.
+      let x := (eval cbv delta [x'] in x') in
+      pose x;
+      let z := (eval cbv iota in x) in
+      pose z.
+
+(*This works fine.  But if I change the period to a semicolon, I get:*)
+
+      Fail let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let y := (eval cbv iota in (let v : T := x in v)) in
+  pose y;
+    let x' := fresh "x'" in
+    pose x as x';
+      let x := (eval cbv delta [x'] in x') in
+      pose x. (* Anomaly: Uncaught exception Not_found. Please report. *)
+ (* should succeed *)
+(*and if I use the second one instead of [pose x] (note that using [idtac] works fine), I get:*)
+
+ Fail  let term := constr:(I) in
+  let T := type of term in
+  let x := constr:((_ : abstract_term term) : T) in
+  let y := (eval cbv iota in (let v : T := x in v)) in
+  pose y;
+    let x' := fresh "x'" in
+    pose x as x';
+      let x := (eval cbv delta [x'] in x') in
+      let z := (eval cbv iota in x) in (* Error: Variable x should be bound to a term. *)
+      idtac. (* should succeed *)