From df91243a1deadfbebf52f795f511b4944cd217ba Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Sat, 21 Aug 2021 20:28:47 +0300
Subject: [PATCH] Whether wchar_t is signed is implementation-defined

---
 include/boost/core/lightweight_test.hpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/boost/core/lightweight_test.hpp b/include/boost/core/lightweight_test.hpp
index 725c247..3b5df89 100644
--- a/include/boost/core/lightweight_test.hpp
+++ b/include/boost/core/lightweight_test.hpp
@@ -181,7 +181,13 @@ inline const void* test_output_impl(std::nullptr_t) { return nullptr; }
 inline int test_output_impl( signed char const& v ) { return v; }
 inline unsigned test_output_impl( unsigned char const& v ) { return v; }
 
-inline unsigned long test_output_impl( wchar_t const& v ) { return v; }
+// Whether wchar_t is signed is implementation-defined
+
+template<bool Signed> struct lwt_long_type {};
+template<> struct lwt_long_type<true> { typedef long type; };
+template<> struct lwt_long_type<false> { typedef unsigned long type; };
+
+inline lwt_long_type<(static_cast<wchar_t>(-1) < static_cast<wchar_t>(0))>::type test_output_impl( wchar_t const& v ) { return v; }
 
 #if !defined( BOOST_NO_CXX11_CHAR16_T )
 inline unsigned long test_output_impl( char16_t const& v ) { return v; }