defer.hpp in passenger-6.0.17

- old
+ new

@@ -17,12 +17,14 @@
 
 #include <boost/asio/detail/config.hpp>
 #include <boost/asio/async_result.hpp>
 #include <boost/asio/detail/type_traits.hpp>
 #include <boost/asio/execution_context.hpp>
+#include <boost/asio/execution/blocking.hpp>
 #include <boost/asio/execution/executor.hpp>
 #include <boost/asio/is_executor.hpp>
+#include <boost/asio/require.hpp>
 
 #include <boost/asio/detail/push_options.hpp>
 
 namespace boost {
 namespace asio {
@@ -66,16 +68,15 @@
  *
  * @li Obtains the handler's associated allocator object @c alloc by performing
  * @code auto alloc = get_associated_allocator(handler); @endcode
  *
  * @li If <tt>execution::is_executor<Ex>::value</tt> is true, performs
- * @code execution::execute(
- *     prefer(
- *       require(ex, execution::blocking.never),
- *       execution::relationship.continuation,
- *       execution::allocator(alloc)),
- *     std::forward<CompletionHandler>(completion_handler)); @endcode
+ * @code prefer(
+ *     require(ex, execution::blocking.never),
+ *     execution::relationship.continuation,
+ *     execution::allocator(alloc)
+ *   ).execute(std::forward<CompletionHandler>(completion_handler)); @endcode
  *
  * @li If <tt>execution::is_executor<Ex>::value</tt> is false, performs
  * @code ex.defer(
  *     std::forward<CompletionHandler>(completion_handler),
  *     alloc); @endcode
@@ -135,31 +136,27 @@
  * function object @c f with a member @c executor_ that is initialised with
  * <tt>prefer(ex1, execution::outstanding_work.tracked)</tt>, a member @c
  * handler_ that is a decay-copy of @c completion_handler, and a function call
  * operator that performs:
  * @code auto a = get_associated_allocator(handler_);
- * execution::execute(
- *     prefer(executor_,
- *       execution::blocking.possibly,
- *       execution::allocator(a)),
- *     std::move(handler_)); @endcode
+ * prefer(executor_, execution::allocator(a)).execute(std::move(handler_));
+ * @endcode
  *
  * @li If <tt>execution::is_executor<Ex1>::value</tt> is false, constructs a
  * function object @c f with a member @c work_ that is initialised with
  * <tt>make_work_guard(ex1)</tt>, a member @c handler_ that is a decay-copy of
  * @c completion_handler, and a function call operator that performs:
  * @code auto a = get_associated_allocator(handler_);
  * work_.get_executor().dispatch(std::move(handler_), a);
  * work_.reset(); @endcode
  *
  * @li If <tt>execution::is_executor<Ex>::value</tt> is true, performs
- * @code execution::execute(
- *     prefer(
- *       require(ex, execution::blocking.never),
- *       execution::relationship.continuation,
- *       execution::allocator(alloc)),
- *     std::move(f)); @endcode
+ * @code prefer(
+ *     require(ex, execution::blocking.never),
+ *     execution::relationship.continuation,
+ *     execution::allocator(alloc)
+ *   ).execute(std::move(f)); @endcode
  *
  * @li If <tt>execution::is_executor<Ex>::value</tt> is false, performs
  * @code ex.defer(std::move(f), alloc); @endcode
  *
  * @par Completion Signature
@@ -171,10 +168,12 @@
 BOOST_ASIO_INITFN_AUTO_RESULT_TYPE_PREFIX(NullaryToken, void()) defer(
     const Executor& ex,
     BOOST_ASIO_MOVE_ARG(NullaryToken) token
       BOOST_ASIO_DEFAULT_COMPLETION_TOKEN(Executor),
     typename constraint<
-      execution::is_executor<Executor>::value || is_executor<Executor>::value
+      (execution::is_executor<Executor>::value
+          && can_require<Executor, execution::blocking_t::never_t>::value)
+        || is_executor<Executor>::value
     >::type = 0)
   BOOST_ASIO_INITFN_AUTO_RESULT_TYPE_SUFFIX((
     async_initiate<NullaryToken, void()>(
         declval<detail::initiate_defer_with_executor<Executor> >(), token)));
 