From b389ac4aea5e3006c9b6a0ecb046c068cdcdefa4 Mon Sep 17 00:00:00 2001
From: Marc Fehling <marc.fehling@gmx.net>
Date: Sun, 4 Aug 2019 09:34:14 -0600
Subject: [PATCH] Added 'boost/type_traits/detail/is_likely_lambda.hpp'.

---
 .../type_traits/detail/is_likely_lambda.hpp   | 95 +++++++++++++++++++
 1 file changed, 95 insertions(+)
 create mode 100644 bundled/boost-1.70.0/include/boost/type_traits/detail/is_likely_lambda.hpp

diff --git a/bundled/boost-1.70.0/include/boost/type_traits/detail/is_likely_lambda.hpp b/bundled/boost-1.70.0/include/boost/type_traits/detail/is_likely_lambda.hpp
new file mode 100644
index 0000000000..21810dda40
--- /dev/null
+++ b/bundled/boost-1.70.0/include/boost/type_traits/detail/is_likely_lambda.hpp
@@ -0,0 +1,95 @@
+/* Copyright 2017 Joaquin M Lopez Munoz.
+ * 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 http://www.boost.org/libs/poly_collection for library home page.
+ */
+
+#ifndef BOOST_TT_DETAIL_IS_LIKELY_STATELESS_LAMBDA_HPP
+#define BOOST_TT_DETAIL_IS_LIKELY_STATELESS_LAMBDA_HPP
+
+#if defined(_MSC_VER)
+#pragma once
+#endif
+
+#include <boost/type_traits/detail/config.hpp>
+#include <boost/type_traits/integral_constant.hpp>
+
+#if defined(BOOST_TT_HAS_ACCURATE_BINARY_OPERATOR_DETECTION)
+//
+// We don't need or use this, just define a dummy class:
+//
+namespace boost{ namespace type_traits_detail{
+
+template<typename T>
+struct is_likely_stateless_lambda : public false_type {};
+
+}}
+
+#elif !defined(BOOST_NO_CXX11_LAMBDAS) && !defined(BOOST_NO_CXX11_DECLTYPE) && !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES) && !BOOST_WORKAROUND(BOOST_MSVC, < 1900)\
+         && !(BOOST_WORKAROUND(BOOST_MSVC, == 1900) && defined(__CLR_VER))
+
+#include <boost/type_traits/is_convertible.hpp>
+#include <boost/type_traits/enable_if.hpp>
+
+namespace boost{
+
+namespace type_traits_detail{
+
+/* Stateless lambda expressions have one (and only one) call operator and are
+ * convertible to a function pointer with the same signature. Non-lambda types
+ * could satisfy this too, hence the "likely" qualifier.
+ */
+
+template<typename T>
+struct has_one_operator_call_helper
+{
+  template<typename Q> static boost::true_type  test(decltype(&Q::operator())*);
+  template<typename>   static boost::false_type test(...);
+
+  using type=decltype(test<T>(nullptr));
+};
+
+template<typename T>
+using has_one_operator_call=typename has_one_operator_call_helper<T>::type;
+
+template<typename T>
+struct equivalent_function_pointer
+{
+  template<typename Q,typename R,typename... Args>
+  static auto helper(R (Q::*)(Args...)const)->R(*)(Args...);
+  template<typename Q,typename R,typename... Args>
+  static auto helper(R (Q::*)(Args...))->R(*)(Args...);
+
+  using type=decltype(helper(&T::operator()));
+};
+
+template<typename T,typename=void>
+struct is_likely_stateless_lambda : false_type{};
+
+template<typename T>
+struct is_likely_stateless_lambda<
+  T,
+  typename boost::enable_if_<has_one_operator_call<T>::value>::type> :
+     boost::is_convertible<T, typename equivalent_function_pointer<T>::type
+>{};
+
+} /* namespace type_traits_detail */
+
+} /* namespace boost */
+
+#else
+ //
+ // Can't implement this:
+ //
+namespace boost {
+   namespace type_traits_detail {
+
+      template<typename T>
+      struct is_likely_stateless_lambda : public boost::integral_constant<bool, false> {};
+}}
+
+#endif
+#endif
+
-- 
2.39.5