From f3782a946f8d01fd5282c150a6d64c4a5a0fccdb Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Sat, 25 Aug 2018 01:47:47 +0300
Subject: [PATCH] Derive noncopyable from a base_token class to allow it to be
 detected by Type Traits without an #include

---
 include/boost/core/noncopyable.hpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/boost/core/noncopyable.hpp b/include/boost/core/noncopyable.hpp
index 6ae8c24..ab30505 100644
--- a/include/boost/core/noncopyable.hpp
+++ b/include/boost/core/noncopyable.hpp
@@ -20,7 +20,14 @@ namespace boost {
 
 namespace noncopyable_  // protection from unintended ADL
 {
-  class noncopyable
+#ifndef BOOST_NONCOPYABLE_BASE_TOKEN_DEFINED
+#define BOOST_NONCOPYABLE_BASE_TOKEN_DEFINED
+
+  struct base_token {};
+
+#endif // #ifndef BOOST_NONCOPYABLE_BASE_TOKEN_DEFINED
+
+  class noncopyable: base_token
   {
   protected:
 #if !defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS) && !defined(BOOST_NO_CXX11_NON_PUBLIC_DEFAULTED_FUNCTIONS)