From 84ca172caa3f5c16304a80c4d087d5c58928baf1 Mon Sep 17 00:00:00 2001
From: Denis Blank <denis.blank@outlook.com>
Date: Wed, 4 Oct 2017 17:16:58 +0200
Subject: [PATCH] Qualify continuable callbacks as r-value callable

---
 .../continuable/continuable-promise-base.hpp  | 12 +++++------
 include/continuable/continuable-trait.hpp     |  4 ++--
 include/continuable/detail/base.hpp           | 20 +++++++++++--------
 include/continuable/detail/composition.hpp    | 12 +++++------
 test/playground/test-playground.cpp           | 10 +++++-----
 5 files changed, 31 insertions(+), 27 deletions(-)

diff --git a/include/continuable/continuable-promise-base.hpp b/include/continuable/continuable-promise-base.hpp
index a48122c..2d568cd 100644
--- a/include/continuable/continuable-promise-base.hpp
+++ b/include/continuable/continuable-promise-base.hpp
@@ -72,29 +72,29 @@ public:
   /// Resolves the continuation with the given values
   ///
   /// \since version 2.0.0
-  void operator()(Args... args) {
-    data_(std::move(args)...);
+  void operator()(Args... args) && {
+    std::move(data_)(std::move(args)...);
   }
   /// Resolves the continuation with the given exception
   ///
   /// \since version 2.0.0
   void operator()(detail::types::dispatch_error_tag tag,
-                  detail::types::error_type exception) {
-    data_(tag, std::move(exception));
+                  detail::types::error_type exception) && {
+    std::move(data_)(tag, std::move(exception));
   }
 
   /// Resolves the continuation with the given values
   ///
   /// \since version 2.0.0
   void set_value(Args... args) {
-    data_(std::move(args)...);
+    std::move(data_)(std::move(args)...);
   }
 
   /// Resolves the continuation with the given exception
   ///
   /// \since version 2.0.0
   void set_exception(detail::types::error_type exception) {
-    data_(detail::types::dispatch_error_tag{}, std::move(exception));
+    std::move(data_)(detail::types::dispatch_error_tag{}, std::move(exception));
   }
 };
 } // namespace cti
diff --git a/include/continuable/continuable-trait.hpp b/include/continuable/continuable-trait.hpp
index c3e714d..292f14a 100644
--- a/include/continuable/continuable-trait.hpp
+++ b/include/continuable/continuable-trait.hpp
@@ -54,8 +54,8 @@ template <template <typename...> class CallbackWrapper,
 struct continuable_trait {
   /// The promise type which is used to resolve continuations
   using promise = promise_base<
-      CallbackWrapper<void(Args...), void(detail::types::dispatch_error_tag,
-                                          detail::types::error_type)>,
+      CallbackWrapper<void(Args...)&&, void(detail::types::dispatch_error_tag,
+                                            detail::types::error_type) &&>,
       detail::hints::signature_hint_tag<Args...>>;
 
   /// The continuable type for the given parameters.
diff --git a/include/continuable/detail/base.hpp b/include/continuable/detail/base.hpp
index 3e0c476..bc33850 100644
--- a/include/continuable/detail/base.hpp
+++ b/include/continuable/detail/base.hpp
@@ -234,10 +234,14 @@ inline auto sequenced_unpack_invoker() {
           util::partial_invoke(std::forward<decltype(callback)>(callback),
                                std::forward<decltype(args)>(args)...);
 
+      // Workaround for MSVC not capturing the reference correctly inside
+      // the lambda.
+      using Next = decltype(next_callback);
+
       traits::unpack(std::move(result), [&](auto&&... types) {
         /// TODO Add inplace resolution here
 
-        std::forward<decltype(next_callback)>(next_callback)(
+        std::forward<Next>(next_callback)(
             std::forward<decltype(types)>(types)...);
       });
     CONTINUABLE_BLOCK_TRY_END
@@ -312,7 +316,7 @@ struct result_handler_base;
 template <typename Base, typename... Args>
 struct result_handler_base<handle_results::no, Base,
                            hints::signature_hint_tag<Args...>> {
-  void operator()(Args... args) {
+  void operator()(Args... args) && {
     // Forward the arguments to the next callback
     std::move(static_cast<Base*>(this)->next_callback_)(std::move(args)...);
   }
@@ -321,7 +325,7 @@ template <typename Base, typename... Args>
 struct result_handler_base<handle_results::yes, Base,
                            hints::signature_hint_tag<Args...>> {
   /// The operator which is called when the result was provided
-  void operator()(Args... args) {
+  void operator()(Args... args) && {
     // In order to retrieve the correct decorator we must know what the
     // result type is.
     auto result = traits::identity_of<decltype(util::partial_invoke(
@@ -356,7 +360,7 @@ inline auto make_error_invoker(
 
 template <handle_errors HandleErrors /* = plain or forward*/, typename Base>
 struct error_handler_base {
-  void operator()(types::dispatch_error_tag, types::error_type error) {
+  void operator()(types::dispatch_error_tag, types::error_type error) && {
     // Just invoke the error handler, cancel the calling hierarchy after
     auto invoker = make_error_invoker(
         std::integral_constant<handle_errors, HandleErrors>{});
@@ -370,7 +374,7 @@ struct error_handler_base {
 template <typename Base>
 struct error_handler_base<handle_errors::no, Base> {
   /// The operator which is called when an error occurred
-  void operator()(types::dispatch_error_tag tag, types::error_type error) {
+  void operator()(types::dispatch_error_tag tag, types::error_type error) && {
     // Forward the error to the next callback
     std::move(static_cast<Base*>(this)->next_callback_)(tag, std::move(error));
   }
@@ -425,12 +429,12 @@ struct callback_base<hints::signature_hint_tag<Args...>, HandleResults,
 
   /// Resolves the continuation with the given values
   void set_value(Args... args) {
-    (*this)(std::move(args)...);
+    std::move (*this)(std::move(args)...);
   }
 
   /// Resolves the continuation with the given error variable.
   void set_exception(types::error_type error) {
-    (*this)(types::dispatch_error_tag{}, std::move(error));
+    std::move (*this)(types::dispatch_error_tag{}, std::move(error));
   }
 };
 
@@ -450,7 +454,7 @@ auto make_callback(Callback&& callback, Executor&& executor,
 /// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64095
 struct final_callback {
   template <typename... Args>
-  void operator()(Args... /*args*/) {
+  void operator()(Args... /*args*/) && {
   }
 
   template <typename... Args>
diff --git a/include/continuable/detail/composition.hpp b/include/continuable/detail/composition.hpp
index 12432b8..9789dca 100644
--- a/include/continuable/detail/composition.hpp
+++ b/include/continuable/detail/composition.hpp
@@ -181,18 +181,18 @@ class all_result_submitter : public std::enable_shared_from_this<
     std::shared_ptr<all_result_submitter> me_;
 
     template <typename... PartialArgs>
-    void operator()(PartialArgs&&... args) {
+    void operator()(PartialArgs&&... args) && {
       me_->resolve(traits::size_constant<From>{}, traits::size_constant<To>{},
                    std::forward<PartialArgs>(args)...);
     }
 
     template <typename... PartialArgs>
     void set_value(PartialArgs&&... args) {
-      (*this)(std::forward<PartialArgs>(args)...);
+      std::move (*this)(std::forward<PartialArgs>(args)...);
     }
 
     void set_exception(types::error_type error) {
-      (*this)(types::dispatch_error_tag{}, std::move(error));
+      std::move (*this)(types::dispatch_error_tag{}, std::move(error));
     }
   };
 
@@ -222,17 +222,17 @@ class any_result_submitter
     std::shared_ptr<any_result_submitter> me_;
 
     template <typename... PartialArgs>
-    void operator()(PartialArgs&&... args) {
+    void operator()(PartialArgs&&... args) && {
       me_->invoke(std::forward<decltype(args)>(args)...);
     }
 
     template <typename... PartialArgs>
     void set_value(PartialArgs&&... args) {
-      (*this)(std::forward<PartialArgs>(args)...);
+      std::move (*this)(std::forward<PartialArgs>(args)...);
     }
 
     void set_exception(types::error_type error) {
-      (*this)(types::dispatch_error_tag{}, std::move(error));
+      std::move (*this)(types::dispatch_error_tag{}, std::move(error));
     }
   };
 
diff --git a/test/playground/test-playground.cpp b/test/playground/test-playground.cpp
index cc1a565..b3d8269 100644
--- a/test/playground/test-playground.cpp
+++ b/test/playground/test-playground.cpp
@@ -29,7 +29,7 @@ static cti::continuable<std::string> http_request(std::string url) {
   return [url = std::move(url)](cti::promise<std::string> promise) {
     if (false) {
       promise.set_value("");
-      promise("");
+      std::forward<decltype(promise)>(promise)("");
     }
     promise.set_exception(std::error_condition{});
   };
@@ -41,7 +41,7 @@ static auto http_request2(std::string url) {
       [url = std::move(url)](auto&& promise) {
         if (false) {
           promise.set_value("");
-          promise("");
+          std::forward<decltype(promise)>(promise)("");
         }
         promise.set_exception(std::error_condition{});
       });
@@ -51,17 +51,17 @@ static cti::continuable<std::string> http_request3(std::string url) {
   return [url = std::move(url)](auto&& promise) {
     if (false) {
       promise.set_value("");
-      promise("");
+      std::forward<decltype(promise)>(promise)("");
     }
     promise.set_exception(std::error_condition{});
   };
 }
 
 struct my_callable {
-  void operator()(std::string) {
+  void operator()(std::string) && {
     // ...
   }
-  void operator()(cti::dispatch_error_tag, cti::error_type) {
+  void operator()(cti::dispatch_error_tag, cti::error_type) && {
     // ...
   }
 };