https://github.com/symengine/symengine/commit/ceae675dccd593f119f3010d46e133de74fc01bc
https://bugs.gentoo.org/808057

From: Liam Keegan <liam@keegan.ch>
Date: Mon, 31 May 2021 21:31:02 +0200
Subject: [PATCH] use list initialization for int parameter since type depends
 on boost version

--- a/symengine/mp_boost.cpp
+++ b/symengine/mp_boost.cpp
@@ -279,7 +279,7 @@ unsigned long mp_scan1(const integer_class &i)
     if (i == 0) {
         return ULONG_MAX;
     }
-    return find_lsb(i, int_<0>());
+    return find_lsb(i, {});
 }
 
 // define simple 2x2 matrix with exponentiation by repeated squaring