Add documentation for rebind C++03 compatibility

CMakeLists.txt

@@ -3,8 +3,6 @@
 # Distributed under the Boost Software License, Version 1.0.
 # https://www.boost.org/LICENSE_1_0.txt
 
-if(NOT DEFINED IDF_TARGET)
-
 cmake_minimum_required(VERSION 3.5...3.20)
 
 project(boost_core VERSION "${BOOST_SUPERPROJECT_VERSION}" LANGUAGES CXX)
@@ -27,22 +25,3 @@ if(BUILD_TESTING AND EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/test/CMakeLists.txt")
   add_subdirectory(test)
 
 endif()
-
-else()
-
-FILE(GLOB_RECURSE headers include/*.h include/*.hpp)
-
-idf_component_register(
-    SRCS
-        ${headers}
-    INCLUDE_DIRS
-        include
-    REQUIRES
-        boost_assert
-        boost_config
-        boost_static_assert
-        boost_throw_exception
-)
-
-endif()
-

doc/pointer_traits.qbk

@@ -113,6 +113,9 @@ also not defined (`pointer_traits` is SFINAE-friendly).
   where `Args` is zero or more type arguments; otherwise, the member is not
   defined.]]]
 
+[note When C++11 template aliases are not supported, the `type` for `rebind` is
+`T::rebind<U>::other` if such a type exists.]
+
 [endsect]
 
 [section Member functions]

include/boost/core/pointer_traits.hpp

@@ -100,11 +100,19 @@ template<class T, class U, class = void>
 struct ptr_rebind
     : ptr_transform<T, U> { };
 
+#if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
 template<class T, class U>
 struct ptr_rebind<T, U,
     typename ptr_valid<typename T::template rebind<U> >::type> {
     typedef typename T::template rebind<U> type;
 };
+#else
+template<class T, class U>
+struct ptr_rebind<T, U,
+    typename ptr_valid<typename T::template rebind<U>::other>::type> {
+    typedef typename T::template rebind<U>::other type;
+};
+#endif
 
 #if !defined(BOOST_NO_CXX11_DECLTYPE_N3276)
 template<class T, class E>

test/pointer_traits_rebind_sfinae_test.cpp

@@ -56,7 +56,7 @@ struct P3 {
     typedef int element_type;
 
     template<class>
-    struct rebind { };
+    using rebind = P3;
 };
 
 template<class T>

test/pointer_traits_sfinae_test.cpp

@@ -64,8 +64,15 @@ struct P2 {
 struct P3 {
     typedef int element_type;
 
+#if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
     template<class>
-    struct rebind { };
+    using rebind = P3;
+#else
+    template<class>
+    struct rebind {
+        typedef P3 other;
+    };
+#endif
 };
 
 template<class T>