From c579b46cfbaafae107d43f003a307ceec7c8057f Mon Sep 17 00:00:00 2001
From: Robbert Krebbers <mail@robbertkrebbers.nl>
Date: Thu, 5 Sep 2019 20:15:37 +0200
Subject: [PATCH] Avoid use of `solve_proper`.

Due to Coq bug #10480 or #10474 it actually used `Morphisms.solve_proper`
instead of the version of std++. The version in std++ can inherently
not solve this, so I changed it into a manual proof.
---
 theories/fin_sets.v | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/theories/fin_sets.v b/theories/fin_sets.v
index cab96743..e71f698a 100644
--- a/theories/fin_sets.v
+++ b/theories/fin_sets.v
@@ -401,7 +401,7 @@ Section infinite.
 
   (** Properties about the [fresh] operation on finite sets *)
   Global Instance fresh_proper: Proper ((≡@{C}) ==> (=)) fresh.
-  Proof. unfold fresh, set_fresh. solve_proper. Qed.
+  Proof. unfold fresh, set_fresh. by intros X1 X2 ->. Qed.
 
   Lemma is_fresh X : fresh X ∉ X.
   Proof.
-- 
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