From 55663153161f99caf4ba5b0bf95290ed6a2e106d Mon Sep 17 00:00:00 2001
From: jzmaddock <john@johnmaddock.co.uk>
Date: Wed, 16 Nov 2022 18:57:05 +0000
Subject: [PATCH] Expand BOOST_ATTRIBUTE_UNUSED [[maybe_unused]] When
 available, supersedes: https://github.com/boostorg/config/pull/456

---
 include/boost/config/detail/suffix.hpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/boost/config/detail/suffix.hpp b/include/boost/config/detail/suffix.hpp
index 898c7ac4..0d451d1f 100644
--- a/include/boost/config/detail/suffix.hpp
+++ b/include/boost/config/detail/suffix.hpp
@@ -1071,9 +1071,22 @@ namespace std{ using ::type_info; }
 //
 // Unused variable/typedef workarounds:
 //
+#ifndef BOOST_ATTRIBUTE_UNUSED
+#  if defined(__has_attribute) && defined(__SUNPRO_CC) && (__SUNPRO_CC > 0x5130)
+#    if __has_attribute(maybe_unused)
+#       define BOOST_ATTRIBUTE_UNUSED [[maybe_unused]]
+#    endif
+#  elif defined(__has_cpp_attribute)
+#    if __has_cpp_attribute(maybe_unused)
+#      define BOOST_ATTRIBUTE_UNUSED [[maybe_unused]]
+#    endif
+#  endif
+#endif
+
 #ifndef BOOST_ATTRIBUTE_UNUSED
 #  define BOOST_ATTRIBUTE_UNUSED
 #endif
+
 //
 // [[nodiscard]]:
 //