From 94201a88ba29fc34bec6498926f0db91d190e458 Mon Sep 17 00:00:00 2001
From: Matt Borland <matt@mattborland.com>
Date: Fri, 28 Oct 2022 07:55:34 -0700
Subject: [PATCH] Use numeric_limits<T>::is_signed to support Boost.MP types

---
 include/boost/math/ccmath/isinf.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/boost/math/ccmath/isinf.hpp b/include/boost/math/ccmath/isinf.hpp
index a07b42aabd..9df492a18a 100644
--- a/include/boost/math/ccmath/isinf.hpp
+++ b/include/boost/math/ccmath/isinf.hpp
@@ -18,7 +18,7 @@ constexpr bool isinf(T x) noexcept
 {
     if(BOOST_MATH_IS_CONSTANT_EVALUATED(x))
     {
-        if constexpr (std::is_signed_v<T>)
+        if constexpr (std::numeric_limits<T>::is_signed)
         {
             return x == std::numeric_limits<T>::infinity() || -x == std::numeric_limits<T>::infinity();
         }