1 files changed, 26 insertions, 0 deletions
diff --git a/test-suite/bugs/closed/shouldsucceed/2733.v b/test-suite/bugs/closed/shouldsucceed/2733.v
new file mode 100644
index 00000000..fd7bd3bd
--- /dev/null
+++ b/test-suite/bugs/closed/shouldsucceed/2733.v
@@ -0,0 +1,26 @@
+Definition goodid : forall {A} (x: A), A := fun A x => x.
+Definition wrongid : forall A (x: A), A := fun {A} x => x.
+
+Inductive ty := N | B.
+
+Inductive alt_list : ty -> ty -> Type :=
+  | nil {k} : alt_list k k
+  | Ncons {k} : nat -> alt_list B k -> alt_list N k
+  | Bcons {k} : bool -> alt_list N k -> alt_list B k.
+
+Definition trullynul k {k'} (l : alt_list k k') :=
+match k,l with
+ |N,l' => Ncons 0 (Bcons true l')
+ |B,l' => Bcons true (Ncons 0 l')
+end.
+
+Fixpoint app (P : forall {k k'}, alt_list k k' -> alt_list k k') {t1 t2} (l : alt_list t1 t2) {struct l}: forall {t3}, alt_list t2 t3 ->
+alt_list t1 t3 :=
+  match l with
+  | nil _ => fun _ l2 => P l2
+  | Ncons _ n l1 => fun _ l2 => Ncons n (app (@P) l1 l2)
+  | Bcons _ b l1 => fun _ l2 => Bcons b (app (@P) l1 l2)
+  end.
+
+Check (fun {t t'} (l: alt_list t t') =>
+ app trullynul (goodid l) (wrongid _ nil)).