Deprecated boost::core::is_same and the associated header.

Moved is_same implementation to detail (both directory and namespace)
to use in the public headers and avoid introducing new dependencies.
The documentation now recommends users to use Boost.TypeTraits or
C++ standard library instead.

Also, removed unnecessary includes and added missing ones in a few
places.

include/boost/core/detail/is_same.hpp

@@ -0,0 +1,39 @@
+#ifndef BOOST_CORE_DETAIL_IS_SAME_HPP_INCLUDED
+#define BOOST_CORE_DETAIL_IS_SAME_HPP_INCLUDED
+
+// is_same<T1,T2>::value is true when T1 == T2
+//
+// Copyright 2014 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
+
+#include <boost/config.hpp>
+
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+# pragma once
+#endif
+
+namespace boost
+{
+namespace core
+{
+namespace detail
+{
+
+template< class T1, class T2 > struct is_same
+{
+    BOOST_STATIC_CONSTANT( bool, value = false );
+};
+
+template< class T > struct is_same< T, T >
+{
+    BOOST_STATIC_CONSTANT( bool, value = true );
+};
+
+} // namespace detail
+} // namespace core
+} // namespace boost
+
+#endif // #ifndef BOOST_CORE_DETAIL_IS_SAME_HPP_INCLUDED

include/boost/core/detail/string_view.hpp

@@ -14,7 +14,7 @@
 // https://www.boost.org/LICENSE_1_0.txt
 
 #include <boost/core/enable_if.hpp>
-#include <boost/core/is_same.hpp>
+#include <boost/core/detail/is_same.hpp>
 #include <boost/assert.hpp>
 #include <boost/assert/source_location.hpp>
 #include <boost/throw_exception.hpp>
@@ -381,7 +381,7 @@ public:
     }
 
     template<class End> BOOST_CXX14_CONSTEXPR basic_string_view( Ch const* first, End last,
-        typename boost::enable_if<is_same<End, Ch const*> >::type* = 0 ) BOOST_NOEXCEPT: p_( first ), n_( last - first )
+        typename boost::enable_if<boost::core::detail::is_same<End, Ch const*> >::type* = 0 ) BOOST_NOEXCEPT: p_( first ), n_( last - first )
     {
         BOOST_ASSERT( last - first >= 0 );
     }
@@ -399,7 +399,7 @@ public:
 #endif
 
     template<class Ch2> basic_string_view( boost::basic_string_view<Ch2, std::char_traits<Ch2> > const& str,
-        typename boost::enable_if<is_same<Ch, Ch2> >::type* = 0 ) BOOST_NOEXCEPT: p_( str.data() ), n_( str.size() )
+        typename boost::enable_if<boost::core::detail::is_same<Ch, Ch2> >::type* = 0 ) BOOST_NOEXCEPT: p_( str.data() ), n_( str.size() )
     {
     }
 
@@ -430,7 +430,7 @@ public:
 
 #if !defined(BOOST_NO_CXX17_HDR_STRING_VIEW)
 
-    template<class Ch2, class En = typename boost::enable_if<is_same<Ch2, Ch> >::type>
+    template<class Ch2, class En = typename boost::enable_if<boost::core::detail::is_same<Ch2, Ch> >::type>
     operator std::basic_string_view<Ch2>() const BOOST_NOEXCEPT
     {
         return std::basic_string_view<Ch>( data(), size() );
@@ -439,7 +439,7 @@ public:
 #endif
 
     template<class Ch2> operator boost::basic_string_view<Ch2,
-        typename boost::enable_if<boost::core::is_same<Ch2, Ch>, std::char_traits<Ch> >::type> () const BOOST_NOEXCEPT
+        typename boost::enable_if<boost::core::detail::is_same<Ch2, Ch>, std::char_traits<Ch> >::type> () const BOOST_NOEXCEPT
     {
         return boost::basic_string_view< Ch, std::char_traits<Ch> >( data(), size() );
     }
@@ -605,7 +605,7 @@ public:
         if( cmp != 0 ) return cmp;
 
         if( size() == str.size() ) return 0;
-        
+
         return size() < str.size()? -1: +1;
     }
 

include/boost/core/is_same.hpp

@@ -1,12 +1,6 @@
 #ifndef BOOST_CORE_IS_SAME_HPP_INCLUDED
 #define BOOST_CORE_IS_SAME_HPP_INCLUDED
 
-// MS compatible compilers support #pragma once
-
-#if defined(_MSC_VER) && (_MSC_VER >= 1020)
-# pragma once
-#endif
-
 // is_same<T1,T2>::value is true when T1 == T2
 //
 // Copyright 2014 Peter Dimov
@@ -16,6 +10,15 @@
 // http://www.boost.org/LICENSE_1_0.txt
 
 #include <boost/config.hpp>
+#include <boost/core/detail/is_same.hpp>
+
+#if defined(BOOST_HAS_PRAGMA_ONCE)
+# pragma once
+#endif
+
+#include <boost/config/header_deprecated.hpp>
+
+BOOST_HEADER_DEPRECATED("<boost/type_traits/is_same.hpp>")
 
 namespace boost
 {
@@ -23,15 +26,7 @@ namespace boost
 namespace core
 {
 
-template< class T1, class T2 > struct is_same
-{
-    BOOST_STATIC_CONSTANT( bool, value = false );
-};
-
-template< class T > struct is_same< T, T >
-{
-    BOOST_STATIC_CONSTANT( bool, value = true );
-};
+using boost::core::detail::is_same;
 
 } // namespace core
 

include/boost/core/lightweight_test_trait.hpp

@@ -22,7 +22,7 @@
 
 #include <boost/core/lightweight_test.hpp>
 #include <boost/core/type_name.hpp>
-#include <boost/core/is_same.hpp>
+#include <boost/core/detail/is_same.hpp>
 #include <boost/config.hpp>
 
 namespace boost
@@ -56,7 +56,7 @@ template<class T> inline bool test_trait_same_impl_( T )
 }
 
 template<class T1, class T2> inline void test_trait_same_impl( char const * types,
-  boost::core::is_same<T1, T2> same, char const * file, int line, char const * function )
+  boost::core::detail::is_same<T1, T2> same, char const * file, int line, char const * function )
 {
     if( test_trait_same_impl_( same ) )
     {
@@ -86,6 +86,6 @@ template<class T1, class T2> inline void test_trait_same_impl( char const * type
 # pragma GCC system_header
 #endif
 
-#define BOOST_TEST_TRAIT_SAME(...) ( ::boost::detail::test_trait_same_impl(#__VA_ARGS__, ::boost::core::is_same<__VA_ARGS__>(), __FILE__, __LINE__, BOOST_CURRENT_FUNCTION) )
+#define BOOST_TEST_TRAIT_SAME(...) ( ::boost::detail::test_trait_same_impl(#__VA_ARGS__, ::boost::core::detail::is_same< __VA_ARGS__ >(), __FILE__, __LINE__, BOOST_CURRENT_FUNCTION) )
 
 #endif // #ifndef BOOST_CORE_LIGHTWEIGHT_TEST_TRAIT_HPP

include/boost/core/type_name.hpp

@@ -14,7 +14,6 @@
 // https://www.boost.org/LICENSE_1_0.txt
 
 #include <boost/core/demangle.hpp>
-#include <boost/core/is_same.hpp>
 #include <boost/config.hpp>
 #include <string>
 #include <functional>