Support BOOST_ASIO_NO_TS_EXECUTORS

include/boost/beast/core/async_base.hpp

@@ -14,10 +14,10 @@
 #include <boost/beast/core/bind_handler.hpp>
 #include <boost/beast/core/detail/allocator.hpp>
 #include <boost/beast/core/detail/async_base.hpp>
+#include <boost/beast/core/detail/work_guard.hpp>
 #include <boost/asio/associated_allocator.hpp>
 #include <boost/asio/associated_executor.hpp>
 #include <boost/asio/bind_executor.hpp>
-#include <boost/asio/executor_work_guard.hpp>
 #include <boost/asio/handler_alloc_hook.hpp>
 #include <boost/asio/handler_continuation_hook.hpp>
 #include <boost/asio/handler_invoke_hook.hpp>
@@ -186,7 +186,27 @@ class async_base
         "Executor type requirements not met");
 
     Handler h_;
-    net::executor_work_guard<Executor1> wg1_;
+    detail::select_work_guard_t<Executor1> wg1_;
+
+public:
+    /** The type of executor associated with this object.
+
+    If a class derived from @ref async_base is a completion
+    handler, then the associated executor of the derived class will
+    be this type.
+*/
+    using executor_type =
+#if BOOST_BEAST_DOXYGEN
+        __implementation_defined__;
+#else
+        typename
+        net::associated_executor<
+            Handler,
+            typename detail::select_work_guard_t<Executor1>::executor_type
+                >::type;
+#endif
+
+private:
 
     virtual
     void
@@ -229,7 +249,7 @@ public:
         Handler_&& handler,
         Executor1 const& ex1)
         : h_(std::forward<Handler_>(handler))
-        , wg1_(ex1)
+        , wg1_(detail::make_work_guard(ex1))
     {
     }
 
@@ -262,15 +282,6 @@ public:
     using allocator_type =
         net::associated_allocator_t<Handler, Allocator>;
 
-    /** The type of executor associated with this object.
-
-        If a class derived from @ref async_base is a completion
-        handler, then the associated executor of the derived class will
-        be this type.
-    */
-    using executor_type =
-        net::associated_executor_t<Handler, Executor1>;
-
     /** Returns the allocator associated with this object.
 
         If a class derived from @ref async_base is a completion
@@ -293,8 +304,7 @@ public:
     executor_type
     get_executor() const noexcept
     {
-        return net::get_associated_executor(
-            h_, wg1_.get_executor());
+        return net::get_associated_executor(h_, wg1_.get_executor());
     }
 
     /// Returns the handler associated with this object

include/boost/beast/core/detail/get_io_context.hpp

@@ -11,6 +11,9 @@
 #define BOOST_BEAST_DETAIL_GET_IO_CONTEXT_HPP
 
 #include <boost/beast/core/stream_traits.hpp>
+#ifdef BOOST_ASIO_NO_TS_EXECUTORS
+#include <boost/asio/execution.hpp>
+#endif
 #include <boost/asio/executor.hpp>
 #include <boost/asio/io_context.hpp>
 #include <boost/asio/strand.hpp>

include/boost/beast/core/detail/work_guard.hpp

@@ -0,0 +1,93 @@
+#ifndef BOOST_BEAST_CORE_DETAIL_WORK_GUARD_HPP
+#define BOOST_BEAST_CORE_DETAIL_WORK_GUARD_HPP
+
+#include <boost/asio/executor_work_guard.hpp>
+#include <boost/asio/execution.hpp>
+#include <boost/optional.hpp>
+
+namespace boost {
+namespace beast {
+namespace detail {
+
+template<class Executor, class Enable = void>
+struct select_work_guard;
+
+template<class Executor>
+using select_work_guard_t = typename
+    select_work_guard<Executor>::type;
+
+#if !defined(BOOST_ASIO_NO_TS_EXECUTORS)
+template<class Executor>
+struct select_work_guard
+<
+    Executor,
+    typename std::enable_if
+    <
+        net::is_executor<Executor>::value
+    >::type
+>
+{
+    using type = net::executor_work_guard<Executor>;
+};
+#endif
+
+template<class Executor>
+struct execution_work_guard
+{
+    using executor_type = decltype(
+        net::prefer(std::declval<Executor const&>(),
+            net::execution::outstanding_work.tracked));
+
+    execution_work_guard(Executor const& exec)
+    : ex_(net::prefer(exec, net::execution::outstanding_work.tracked))
+    {
+
+    }
+
+    executor_type
+    get_executor() const noexcept
+    {
+        BOOST_ASSERT(ex_.has_value());
+        return *ex_;
+    }
+
+    void reset() noexcept
+    {
+        ex_.reset();
+    }
+
+private:
+
+    boost::optional<executor_type> ex_;
+};
+
+template<class Executor>
+struct select_work_guard
+<
+    Executor,
+    typename std::enable_if
+    <
+        net::execution::is_executor<Executor>::value
+#if defined(BOOST_ASIO_NO_TS_EXECUTORS)
+        || net::is_executor<Executor>::value
+#else
+        && !net::is_executor<Executor>::value
+#endif
+    >::type
+>
+{
+    using type = execution_work_guard<Executor>;
+};
+
+template<class Executor>
+select_work_guard_t<Executor>
+make_work_guard(Executor const& exec) noexcept
+{
+    return select_work_guard_t<Executor>(exec);
+}
+
+}
+}
+}
+
+#endif // BOOST_BEAST_CORE_DETAIL_WORK_GUARD_HPP

include/boost/beast/core/impl/saved_handler.hpp

@@ -64,9 +64,10 @@ class saved_handler::impl final : public base
 
     ebo_pair v_;
 #if defined(BOOST_ASIO_NO_TS_EXECUTORS)
-    std::decay_t<decltype(net::prefer(
-          std::declval<net::associated_executor_t<Handler>>(),
-          net::execution::outstanding_work.tracked))> wg2_;
+    typename std::decay<decltype(net::prefer(std::declval<
+        net::associated_executor_t<Handler>>(),
+        net::execution::outstanding_work.tracked))>::type
+          wg2_;
 #else // defined(BOOST_ASIO_NO_TS_EXECUTORS)
     net::executor_work_guard<
         net::associated_executor_t<Handler>> wg2_;

include/boost/beast/websocket/impl/stream_impl.hpp

@@ -128,7 +128,8 @@ struct stream<NextLayer, deflateSupported>::impl_type
             boost::empty_init_t{},
             std::forward<Args>(args)...)
         , detail::service::impl_type(
-            this->boost::empty_value<NextLayer>::get().get_executor().context())
+            net::query(this->boost::empty_value<NextLayer>::get().get_executor(),
+                net::execution::context))
         , timer(this->boost::empty_value<NextLayer>::get().get_executor())
     {
         timeout_opt.handshake_timeout = none();