1 files changed, 71 insertions, 10 deletions

diff --git a/src/concurrent/qtconcurrentstoredfunctioncall.h b/src/concurrent/qtconcurrentstoredfunctioncall.h
index 1257d70b829..f52b6e2efc0 100644
--- a/src/concurrent/qtconcurrentstoredfunctioncall.h
+++ b/src/concurrent/qtconcurrentstoredfunctioncall.h
@@ -102,17 +102,21 @@ template <class IsMember, class Function, class PromiseType, class... Args>
 struct FunctionResolverHelper;
 
 template <class Function, class PromiseType, class... Args>
-struct FunctionResolverHelper<std::false_type, Function, PromiseType, Args...> : public NonMemberFunctionResolver<Function, PromiseType, Args...>
+struct FunctionResolverHelper<std::false_type, Function, PromiseType, Args...>
+        : public NonMemberFunctionResolver<Function, PromiseType, Args...>
 {
 };
 
 template <class Function, class PromiseType, class... Args>
-struct FunctionResolverHelper<std::true_type, Function, PromiseType, Args...> : public MemberFunctionResolver<Function, PromiseType, Args...>
+struct FunctionResolverHelper<std::true_type, Function, PromiseType, Args...>
+        : public MemberFunctionResolver<Function, PromiseType, Args...>
 {
 };
 
 template <class Function, class PromiseType, class... Args>
-struct FunctionResolver : public FunctionResolverHelper<typename std::is_member_function_pointer<std::decay_t<Function>>::type, Function, PromiseType, Args...>
+struct FunctionResolver
+        : public FunctionResolverHelper<typename std::is_member_function_pointer<
+                 std::decay_t<Function>>::type, Function, PromiseType, Args...>
 {
 };
 
@@ -134,10 +138,6 @@ using DecayedTuple = std::tuple<std::decay_t<Types>...>;
 template <class Function, class ...Args>
 struct StoredFunctionCall : public RunFunctionTask<InvokeResultType<Function, Args...>>
 {
-    StoredFunctionCall(Function &&f, Args &&...args)
-        : data{std::forward<Function>(f), std::forward<Args>(args)...}
-    {}
-
     StoredFunctionCall(DecayedTuple<Function, Args...> &&_data)
         : data(std::move(_data))
     {}
@@ -165,11 +165,13 @@ struct StoredFunctionCallWithPromise : public RunFunctionTaskBase<PromiseType>
     using DataType = typename Resolver::Type;
     StoredFunctionCallWithPromise(Function &&f, Args &&...args)
         : prom(this->promise),
-          data(std::move(Resolver::initData(std::forward<Function>(f), std::ref(prom), std::forward<Args>(args)...)))
+          data(std::move(Resolver::initData(std::forward<Function>(f), std::ref(prom),
+                                            std::forward<Args>(args)...)))
     {}
 
-    StoredFunctionCallWithPromise(DataType &&_data)
-        : data(std::move(_data))
+    StoredFunctionCallWithPromise(DecayedTuple<Function, Args...> &&_data)
+        : StoredFunctionCallWithPromise(std::move(_data),
+               std::index_sequence_for<std::decay_t<Function>, std::decay_t<Args>...>())
     {}
 
 protected:
@@ -179,10 +181,69 @@ protected:
     }
 
 private:
+    // helper to pack back the tuple into parameter pack
+    template<std::size_t... Is>
+    StoredFunctionCallWithPromise(DecayedTuple<Function, Args...> &&_data,
+                                  std::index_sequence<Is...>)
+        : StoredFunctionCallWithPromise(std::move(std::get<Is>(_data))...)
+    {}
+
     QPromise<PromiseType> prom;
     DataType data;
 };
 
+template<typename...>
+struct NonPromiseTaskResolver;
+
+template <typename Function, typename ... Args>
+struct NonPromiseTaskResolver<Function, Args...>
+{
+    using TaskWithArgs = DecayedTuple<Function, Args...>;
+    static auto run(TaskWithArgs &&args, const TaskStartParameters &startParameters) {
+        return (new StoredFunctionCall<Function, Args...>(std::move(args)))
+                ->start(startParameters);
+    }
+};
+
+template<typename...>
+struct PromiseTaskResolver;
+
+template <typename Function, typename ... Args>
+struct PromiseTaskResolver<Function, Args...>
+{
+    static_assert(QtPrivate::ArgResolver<Function>::IsPromise::value,
+        "The first argument of passed callable object isn't a QPromise<T> & type. "
+        "Did you intend to pass a callable which takes a QPromise<T> & type as a first argument? "
+        "Otherwise it's not possible to invoke the function with passed arguments.");
+    using TaskWithArgs = DecayedTuple<Function, Args...>;
+    static auto run(TaskWithArgs &&args, const TaskStartParameters &startParameters) {
+        using PromiseType = typename QtPrivate::ArgResolver<Function>::PromiseType;
+        return (new StoredFunctionCallWithPromise<Function, PromiseType, Args...>(std::move(args)))
+                   ->start(startParameters);
+    }
+};
+
+template <class IsDirectlyInvocable, class Function, class... Args>
+struct TaskResolverHelper;
+
+template <class Function, class... Args>
+struct TaskResolverHelper<std::true_type, Function, Args...>
+        : public NonPromiseTaskResolver<Function, Args...>
+{
+};
+
+template <class Function, class... Args>
+struct TaskResolverHelper<std::false_type, Function, Args...>
+        : public PromiseTaskResolver<Function, Args...>
+{
+};
+
+template <class Function, class... Args>
+struct TaskResolver : public TaskResolverHelper<typename std::is_invocable<std::decay_t<Function>,
+        std::decay_t<Args>...>::type, Function, Args...>
+{
+};
+
 } //namespace QtConcurrent
 
 #endif // Q_QDOC