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 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

(limited to 'pretyping')

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'
-- 
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