From f897f32064b43321abe6d66e169e863bc38cd6bc Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@gmail.com>
Date: Sat, 1 Nov 2025 17:07:54 +0200
Subject: [PATCH] Extract nontype_t to its own header; add nontype

---
 include/boost/compat/function_ref.hpp | 14 +---------
 include/boost/compat/nontype.hpp      | 37 +++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 13 deletions(-)
 create mode 100644 include/boost/compat/nontype.hpp

diff --git a/include/boost/compat/function_ref.hpp b/include/boost/compat/function_ref.hpp
index 2838ce1..d9d5719 100644
--- a/include/boost/compat/function_ref.hpp
+++ b/include/boost/compat/function_ref.hpp
@@ -5,31 +5,19 @@
 // Distributed under the Boost Software License, Version 1.0.
 // https://www.boost.org/LICENSE_1_0.txt
 
+#include <boost/compat/nontype.hpp>
 #include <boost/compat/invoke.hpp>
 #include <boost/compat/type_traits.hpp>
 
 #include <type_traits>
 #include <utility>
 
-#if defined(__cpp_nontype_template_parameter_auto) && __cpp_nontype_template_parameter_auto >= 201606L
-#define BOOST_COMPAT_HAS_AUTO_NTTP
-#endif
-
 namespace boost {
 namespace compat {
 
 template <class... S>
 struct function_ref;
 
-#if defined(BOOST_COMPAT_HAS_AUTO_NTTP)
-
-template <auto V>
-struct nontype_t {
-  explicit nontype_t() = default;
-};
-
-#endif
-
 namespace detail {
 
 template <bool NoEx>
diff --git a/include/boost/compat/nontype.hpp b/include/boost/compat/nontype.hpp
new file mode 100644
index 0000000..5f05204
--- /dev/null
+++ b/include/boost/compat/nontype.hpp
@@ -0,0 +1,37 @@
+#ifndef BOOST_COMPAT_NONTYPE_HPP_INCLUDED
+#define BOOST_COMPAT_NONTYPE_HPP_INCLUDED
+
+// Copyright 2024 Christian Mazakas
+// Copyright 2025 Peter Dimov
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/config.hpp>
+
+#if defined(__cpp_nontype_template_parameter_auto) && __cpp_nontype_template_parameter_auto >= 201606L
+#define BOOST_COMPAT_HAS_AUTO_NTTP
+#endif
+
+namespace boost {
+namespace compat {
+
+#if defined(BOOST_COMPAT_HAS_AUTO_NTTP)
+
+template <auto V>
+struct nontype_t {
+  explicit nontype_t() = default;
+};
+
+# if defined(__cpp_variable_templates) && __cpp_variable_templates >= 201304L
+
+template<auto V>
+BOOST_INLINE_CONSTEXPR nontype_t<V> nontype {};
+
+# endif
+
+#endif
+
+} // namespace compat
+} // namespace boost
+
+#endif // BOOST_COMPAT_NONTYPE_HPP_INCLUDED