From 2727af30f9338830c2b225587f87ed8a4e80f7e3 Mon Sep 17 00:00:00 2001
From: Gaëtan Gilbert
Date: Fri, 19 Jul 2019 12:59:13 +0200
Subject: Fix #10533: uncaught Invalid_argument Array.fold_left2 in rewrite

---
 pretyping/unification.ml           | 5 +++--
 test-suite/bugs/closed/bug_10533.v | 8 ++++++++
 2 files changed, 11 insertions(+), 2 deletions(-)
 create mode 100644 test-suite/bugs/closed/bug_10533.v

diff --git a/pretyping/unification.ml b/pretyping/unification.ml
index 00831b5962..a9eb43e573 100644
--- a/pretyping/unification.ml
+++ b/pretyping/unification.ml
@@ -839,8 +839,9 @@ let rec unify_0_with_initial_metas (sigma,ms,es as subst : subst0) conv_at_top e
 	       unify_app_pattern true curenvnb pb opt substn cM f1 l1 cN f2 l2
 	     | _ -> raise ex)
 
-	| Case (_,p1,c1,cl1), Case (_,p2,c2,cl2) ->
-            (try 
+        | Case (ci1,p1,c1,cl1), Case (ci2,p2,c2,cl2) ->
+            (try
+             if not (eq_ind ci1.ci_ind ci2.ci_ind) then error_cannot_unify curenv sigma (cM,cN);
 	     let opt' = {opt with at_top = true; with_types = false} in
 	       Array.fold_left2 (unirec_rec curenvnb CONV {opt with at_top = true})
 	       (unirec_rec curenvnb CONV opt'
diff --git a/test-suite/bugs/closed/bug_10533.v b/test-suite/bugs/closed/bug_10533.v
new file mode 100644
index 0000000000..e72957bdee
--- /dev/null
+++ b/test-suite/bugs/closed/bug_10533.v
@@ -0,0 +1,8 @@
+
+Require Import Eqdep Setoid.
+Goal forall (t : unit) (pf : tt = t),
+  if (match pf with eq_refl => false end) then True else False.
+Proof.
+  intros.
+  try setoid_rewrite <-Eqdep.Eq_rect_eq.eq_rect_eq.
+Abort.
-- 
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