From 60591642995477c099728d2ecf7d5d2533e642aa Mon Sep 17 00:00:00 2001
From: Jarek Kobus <jaroslaw.kobus@qt.io>
Date: Thu, 2 Nov 2023 15:29:16 +0100
Subject: [PATCH] TaskTree: Make setup handler optional

Change-Id: Idfcaaf5cc5f69895d8cf9bf6e4ee673e524b61fe
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
---
 src/libs/solutions/tasking/tasktree.cpp      |  4 ++--
 src/libs/solutions/tasking/tasktree.h        | 17 ++++++++++-------
 tests/auto/solutions/tasking/tst_tasking.cpp |  6 +++++-
 3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/src/libs/solutions/tasking/tasktree.cpp b/src/libs/solutions/tasking/tasktree.cpp
index c8347af1bb8..348481c8fc9 100644
--- a/src/libs/solutions/tasking/tasktree.cpp
+++ b/src/libs/solutions/tasking/tasktree.cpp
@@ -956,8 +956,8 @@ void GroupItem::addChildren(const QList<GroupItem> &children)
 GroupItem GroupItem::withTimeout(const GroupItem &item, milliseconds timeout,
                                  const GroupEndHandler &handler)
 {
-    const TimeoutTask::EndHandler taskHandler = handler
-        ? [handler](const milliseconds &) { handler(); } : TimeoutTask::EndHandler();
+    const TimeoutTask::EndFunction taskHandler = handler
+        ? [handler](const milliseconds &) { handler(); } : TimeoutTask::EndFunction();
     return Group {
         parallel,
         stopOnFinished,
diff --git a/src/libs/solutions/tasking/tasktree.h b/src/libs/solutions/tasking/tasktree.h
index 5b94cfc3099..99edad20272 100644
--- a/src/libs/solutions/tasking/tasktree.h
+++ b/src/libs/solutions/tasking/tasktree.h
@@ -324,17 +324,18 @@ public:
     static_assert(std::is_base_of_v<TaskAdapter<Task, Deleter>, Adapter>,
                   "The Adapter type for the CustomTask<Adapter> needs to be derived from "
                   "TaskAdapter<Task>.");
-    using DoneHandler = std::function<void(const Task &, bool)>;
-    using EndHandler = std::function<void(const Task &)>;
+    using SetupFunction = std::function<void(const Task &)>;
+    using DoneFunction = std::function<void(const Task &, bool)>;
+    using EndFunction = std::function<void(const Task &)>;
     static Adapter *createAdapter() { return new Adapter; }
     CustomTask() : GroupItem({&createAdapter}) {}
-    template <typename SetupHandler>
-    CustomTask(SetupHandler &&setup, const EndHandler &done = {}, const EndHandler &error = {})
+    template <typename SetupHandler = SetupFunction>
+    CustomTask(SetupHandler &&setup, const EndFunction &done = {}, const EndFunction &error = {})
         : GroupItem({&createAdapter, wrapSetup(std::forward<SetupHandler>(setup)),
                      wrapEnds(done, error)}) {}
 
     template <typename SetupHandler>
-    CustomTask(SetupHandler &&setup, const DoneHandler &done)
+    CustomTask(SetupHandler &&setup, const DoneFunction &done)
         : GroupItem({&createAdapter, wrapSetup(std::forward<SetupHandler>(setup)), wrapDone(done)})
     {}
 
@@ -346,6 +347,8 @@ public:
 private:
     template<typename SetupHandler>
     static GroupItem::TaskSetupHandler wrapSetup(SetupHandler &&handler) {
+        if constexpr (std::is_same_v<SetupHandler, std::function<void()>>)
+            return {}; // When user passed {} for setup handler.
         static constexpr bool isDynamic = std::is_same_v<SetupResult,
                 std::invoke_result_t<std::decay_t<SetupHandler>, typename Adapter::TaskType &>>;
         constexpr bool isVoid = std::is_same_v<void,
@@ -362,7 +365,7 @@ private:
         };
     };
 
-    static TaskDoneHandler wrapEnds(const EndHandler &doneHandler, const EndHandler &errorHandler) {
+    static TaskDoneHandler wrapEnds(const EndFunction &doneHandler, const EndFunction &errorHandler) {
         if (!doneHandler && !errorHandler)
             return {};
         return [doneHandler, errorHandler](const TaskInterface &taskInterface, bool success) {
@@ -373,7 +376,7 @@ private:
         };
     };
 
-    static TaskDoneHandler wrapDone(const DoneHandler &handler) {
+    static TaskDoneHandler wrapDone(const DoneFunction &handler) {
         if (!handler)
             return {};
         return [handler](const TaskInterface &taskInterface, bool success) {
diff --git a/tests/auto/solutions/tasking/tst_tasking.cpp b/tests/auto/solutions/tasking/tst_tasking.cpp
index 72927b68d47..546b876be57 100644
--- a/tests/auto/solutions/tasking/tst_tasking.cpp
+++ b/tests/auto/solutions/tasking/tst_tasking.cpp
@@ -117,12 +117,16 @@ void tst_Tasking::validConstructs()
 
     const Group task2 {
         parallel,
+        TestTask(),
         TestTask(setupHandler),
         TestTask(setupHandler, finishHandler),
         TestTask(setupHandler, finishHandler, errorHandler),
         TestTask(setupHandler, doneHandler),
         // need to explicitly pass empty handler for done
-        TestTask(setupHandler, {}, errorHandler)
+        TestTask(setupHandler, {}, errorHandler),
+        TestTask({}, finishHandler),
+        TestTask({}, finishHandler, errorHandler),
+        TestTask({}, {}, errorHandler)
     };
 
     // When turning each of below blocks on, you should see the specific compiler error message.