1 files changed, 29 insertions, 0 deletions
diff --git a/test-suite/bugs/closed/shouldsucceed/1931.v b/test-suite/bugs/closed/shouldsucceed/1931.v
new file mode 100644
index 00000000..bc8be78f
--- /dev/null
+++ b/test-suite/bugs/closed/shouldsucceed/1931.v
@@ -0,0 +1,29 @@
+
+
+Set Implicit Arguments.
+
+Inductive T (A:Set) : Set :=
+ app : T A -> T A -> T A.
+
+Fixpoint map (A B:Set)(f:A->B)(t:T A) : T B :=
+ match t with
+   app t1 t2 => app (map f t1)(map f t2)
+ end. 
+
+Fixpoint subst (A B:Set)(f:A -> T B)(t:T A) :T B :=
+ match t with
+    app t1 t2 => app (subst f t1)(subst f t2)
+ end.
+
+(* This is the culprit: *)
+Definition k0:=Set.
+
+(** interaction of subst with map *)
+Lemma substLaw1 (A:k0)(B C:Set)(f: A -> B)(g:B -> T C)(t: T A): 
+ subst g (map f t) = subst (fun x => g (f x)) t.
+Proof.
+ intros.
+ generalize B C f g; clear B C f g.
+ induction t; intros; simpl.
+ f_equal.
+Admitted.