Add a noexcept overload of message() taking a buffer

test/generic_category_test.cpp

@@ -0,0 +1,41 @@
+
+// Copyright 2018 Peter Dimov.
+//
+// Distributed under the Boost Software License, Version 1.0.
+//
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+
+// See library home page at http://www.boost.org/libs/system
+
+// Avoid spurious VC++ warnings
+# define _CRT_SECURE_NO_WARNINGS
+
+#include <boost/system/error_code.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <cstring>
+
+//
+
+namespace sys = boost::system;
+
+int main()
+{
+    sys::error_category const & cat = sys::generic_category();
+
+    // message
+
+    for( int i = -1; i < 1024; ++i )
+    {
+        {
+            BOOST_TEST_CSTR_EQ( cat.message( i ).c_str(), std::strerror( i ) );
+        }
+
+        {
+            char buffer[ 256 ];
+            BOOST_TEST_CSTR_EQ( cat.message( i, buffer, sizeof( buffer ) ), std::strerror( i ) );
+        }
+    }
+
+    return boost::report_errors();
+}