From 99f9654f18a7ae2820d65972c01501515e864d33 Mon Sep 17 00:00:00 2001
From: Andrey Semashev <andrey.semashev@gmail.com>
Date: Sat, 7 Jan 2023 01:06:41 +0300
Subject: [PATCH] Fixed incorrect preprocessor condition for ref_empty
 definition.

Closes https://github.com/boostorg/core/pull/137.
---
 include/boost/core/ref.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/boost/core/ref.hpp b/include/boost/core/ref.hpp
index 46db5fe..d29a4d6 100644
--- a/include/boost/core/ref.hpp
+++ b/include/boost/core/ref.hpp
@@ -59,7 +59,7 @@ template< class Y, class T > struct ref_convertible
     enum _vt { value = sizeof( (f)( static_cast<Y*>(0) ) ) == sizeof(yes) };
 };
 
-#if !defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS)
+#if defined(BOOST_NO_CXX11_FUNCTION_TEMPLATE_DEFAULT_ARGS)
 struct ref_empty
 {
 };