Do QFutureWatcher::setFuture() after connecting to watcher's signals

Otherwise we may have race condition.
Reference: documentation for QFutureWatcher::setFuture()
and the implementation of
QFutureInterfaceBasePrivate::connectOutputInterface(
QFutureCallOutInterface *interface).

Change-Id: I5b483baaf1b844871a162f47ce7683e9ff495acb
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/coreplugin/progressmanager/progressmanager.cpp

@@ -377,7 +377,6 @@ FutureProgress *ProgressManagerPrivate::doAddTask(const QFuture<void> &future, c
     connect(watcher, &QFutureWatcherBase::progressValueChanged,
             this, &ProgressManagerPrivate::updateSummaryProgressBar);
     connect(watcher, &QFutureWatcherBase::finished, this, &ProgressManagerPrivate::taskFinished);
-    watcher->setFuture(future);
 
     // handle application task
     if (flags & ShowInApplicationIcon) {
@@ -393,6 +392,8 @@ FutureProgress *ProgressManagerPrivate::doAddTask(const QFuture<void> &future, c
         setApplicationProgressVisible(true);
     }
 
+    watcher->setFuture(future);
+
     // create FutureProgress and manage task list
     removeOldTasks(type);
     if (m_taskList.size() == 10)

src/plugins/git/gitgrep.cpp

@@ -190,9 +190,9 @@ public:
         command->addFlags(VcsCommand::SilentOutput | VcsCommand::SuppressFailMessage);
         command->setProgressiveOutput(true);
         QFutureWatcher<FileSearchResultList> watcher;
-        watcher.setFuture(m_fi.future());
         connect(&watcher, &QFutureWatcher<FileSearchResultList>::canceled,
                 command.data(), &VcsCommand::cancel);
+        watcher.setFuture(m_fi.future());
         connect(command.data(), &VcsCommand::stdOutText, this, &GitGrepRunner::read);
         SynchronousProcessResponse resp = command->runCommand({GitClient::instance()->vcsBinary(), arguments}, 0);
         switch (resp.result) {

src/plugins/help/searchwidget.cpp

@@ -185,9 +185,9 @@ void SearchWidget::indexingStarted()
     m_progress->setProgressValueAndText(1, tr("Indexing Documentation"));
     m_progress->reportStarted();
 
-    m_watcher.setFuture(m_progress->future());
     connect(&m_watcher, &QFutureWatcherBase::canceled,
             searchEngine, &QHelpSearchEngine::cancelIndexing);
+    m_watcher.setFuture(m_progress->future());
 
     m_queryWidget->hide();
     m_indexingDocumentationLabel->show();

src/plugins/ios/simulatoroperationdialog.cpp

@@ -75,9 +75,9 @@ void SimulatorOperationDialog::addFutures(const QList<QFuture<void> > &futureLis
     foreach (auto future, futureList) {
         if (!future.isFinished() || !future.isCanceled()) {
             auto watcher = new QFutureWatcher<void>;
-            watcher->setFuture(future);
             connect(watcher, &QFutureWatcher<void>::finished,
                     this, &SimulatorOperationDialog::futureFinished);
+            watcher->setFuture(future);
             m_futureWatchList << watcher;
         }
     }

src/plugins/languageclient/languageclientformatter.cpp

@@ -113,10 +113,10 @@ QFutureWatcher<ChangeSet> *LanguageClientFormatter::format(
     m_ignoreCancel = true;
     m_progress.reportStarted();
     auto watcher = new QFutureWatcher<ChangeSet>();
-    watcher->setFuture(m_progress.future());
     QObject::connect(watcher, &QFutureWatcher<Text::Replacements>::canceled, [this]() {
         cancelCurrentRequest();
     });
+    watcher->setFuture(m_progress.future());
     return watcher;
 }
 

src/plugins/languageclient/locatorfilter.cpp

@@ -162,11 +162,11 @@ QList<Core::LocatorFilterEntry> DocumentLocatorFilter::matchesFor(
         QEventLoop loop;
         connect(this, &DocumentLocatorFilter::symbolsUpToDate, &loop, [&]() { loop.exit(1); });
         QFutureWatcher<Core::LocatorFilterEntry> watcher;
-        watcher.setFuture(future.future());
         connect(&watcher,
                 &QFutureWatcher<Core::LocatorFilterEntry>::canceled,
                 &loop,
                 &QEventLoop::quit);
+        watcher.setFuture(future.future());
         locker.unlock();
         if (!loop.exec())
             return {};
@@ -263,11 +263,11 @@ QList<Core::LocatorFilterEntry> WorkspaceLocatorFilter::matchesFor(
         QEventLoop loop;
         connect(this, &WorkspaceLocatorFilter::allRequestsFinished, &loop, [&]() { loop.exit(1); });
         QFutureWatcher<Core::LocatorFilterEntry> watcher;
-        watcher.setFuture(future.future());
         connect(&watcher,
                 &QFutureWatcher<Core::LocatorFilterEntry>::canceled,
                 &loop,
                 &QEventLoop::quit);
+        watcher.setFuture(future.future());
         locker.unlock();
         if (!loop.exec())
             return {};

src/plugins/python/pythonutils.cpp

@@ -381,7 +381,6 @@ void PyLSConfigureAssistant::openDocumentWithPython(const FilePath &python,
     using CheckPylsWatcher = QFutureWatcher<PythonLanguageServerState>;
 
     QPointer<CheckPylsWatcher> watcher = new CheckPylsWatcher();
-    watcher->setFuture(Utils::runAsync(&checkPythonLanguageServer, python));
 
     // cancel and delete watcher after a 10 second timeout
     QTimer::singleShot(10000, this, [watcher]() {
@@ -401,6 +400,7 @@ void PyLSConfigureAssistant::openDocumentWithPython(const FilePath &python,
             handlePyLSState(python, watcher->result(), document);
             watcher->deleteLater();
         });
+    watcher->setFuture(Utils::runAsync(&checkPythonLanguageServer, python));
 }
 
 void PyLSConfigureAssistant::handlePyLSState(const FilePath &python,