From b464cf26bc1fa6340f8e0ec1bb8656ac508db1fe Mon Sep 17 00:00:00 2001
From: Mathias Soeken <a-masoek@microsoft.com>
Date: Wed, 19 Feb 2020 15:23:47 +0100
Subject: [PATCH] Passing functor by const-reference allows to use lambdas as
 arguments.

---
 src/sat/sat_aig_finder.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/sat/sat_aig_finder.h b/src/sat/sat_aig_finder.h
index ab29d3c1a..83e8fcaf4 100644
--- a/src/sat/sat_aig_finder.h
+++ b/src/sat/sat_aig_finder.h
@@ -53,8 +53,8 @@ namespace sat {
     public:
         aig_finder(solver& s);
         ~aig_finder() {}                
-        void set(std::function<void (literal head, literal_vector const& ands)>& f) { m_on_aig = f; }
-        void set(std::function<void (literal head, literal cond, literal th, literal el)>& f) { m_on_if = f; }
+        void set(std::function<void (literal head, literal_vector const& ands)> const& f) { m_on_aig = f; }
+        void set(std::function<void (literal head, literal cond, literal th, literal el)> const& f) { m_on_if = f; }
         void operator()(clause_vector& clauses);
     };
 }