Changed http to https in URLs in readme.

.travis.yml

@@ -210,6 +210,17 @@ matrix:
             - ubuntu-toolchain-r-test
             - llvm-toolchain-trusty-6.0
 
+    - os: linux
+      compiler: clang++-7
+      env: TOOLSET=clang COMPILER=clang++-7 CXXSTD=03,11,14,17
+      addons:
+        apt:
+          packages:
+            - clang-7
+          sources:
+            - ubuntu-toolchain-r-test
+            - llvm-toolchain-trusty-7
+
     - os: linux
       compiler: clang++-6.0
       env: UBSAN=1 TOOLSET=clang COMPILER=clang++-6.0 CXXSTD=03,11,14,1z UBSAN_OPTIONS=print_stacktrace=1

README.md

@@ -1,7 +1,7 @@
 Boost.Core
 ==========
 
-Boost.Core, part of collection of the [Boost C++ Libraries](http://github.com/boostorg), is a collection of core utilities used by other Boost libraries.
+Boost.Core, part of collection of the [Boost C++ Libraries](https://github.com/boostorg), is a collection of core utilities used by other Boost libraries.
 The criteria for inclusion is that the utility component be:
 
 * simple,
@@ -23,10 +23,10 @@ Master   | [![Build Status](https://travis-ci.org/boostorg/core.svg?branch=maste
 
 ### More information
 
-* [Documentation](http://boost.org/libs/core)
+* [Documentation](https://boost.org/libs/core)
 * [Report bugs](https://svn.boost.org/trac/boost/newticket?component=core;version=Boost%20Release%20Branch). Be sure to mention Boost version, platform and compiler you're using. A small compilable code sample to reproduce the problem is always good as well.
-* Submit your patches as pull requests against **develop** branch. Note that by submitting patches you agree to license your modifications under the [Boost Software License, Version 1.0](http://www.boost.org/LICENSE_1_0.txt).
+* Submit your patches as pull requests against **develop** branch. Note that by submitting patches you agree to license your modifications under the [Boost Software License, Version 1.0](https://www.boost.org/LICENSE_1_0.txt).
 
 ### License
 
-Distributed under the [Boost Software License, Version 1.0](http://boost.org/LICENSE_1_0.txt).
+Distributed under the [Boost Software License, Version 1.0](https://boost.org/LICENSE_1_0.txt).

include/boost/core/swap.hpp

@@ -21,13 +21,19 @@
 // avoid ambiguity when swapping objects of a Boost type that does
 // not have its own boost::swap overload.
 
+#include <boost/core/enable_if.hpp>
+#include <boost/config.hpp>
 #include <utility> //for std::swap (C++11)
 #include <algorithm> //for std::swap (C++98)
 #include <cstddef> //for std::size_t
-#include <boost/config.hpp>
 
 namespace boost_swap_impl
 {
+  // we can't use type_traits here
+
+  template<class T> struct is_const { enum _vt { value = 0 }; };
+  template<class T> struct is_const<T const> { enum _vt { value = 1 }; };
+
   template<class T>
   BOOST_GPU_ENABLED
   void swap_impl(T& left, T& right)
@@ -51,7 +57,8 @@ namespace boost
 {
   template<class T1, class T2>
   BOOST_GPU_ENABLED
-  void swap(T1& left, T2& right)
+  typename enable_if_c< !boost_swap_impl::is_const<T1>::value && !boost_swap_impl::is_const<T2>::value >::type
+  swap(T1& left, T2& right)
   {
     ::boost_swap_impl::swap_impl(left, right);
   }