1 files changed, 29 insertions, 35 deletions

diff --git a/src/corelib/thread/qthreadpool.cpp b/src/corelib/thread/qthreadpool.cpp
index 51783321b9..ae584656fe 100644
--- a/src/corelib/thread/qthreadpool.cpp
+++ b/src/corelib/thread/qthreadpool.cpp
@@ -6,6 +6,8 @@
 #include "qdeadlinetimer.h"
 #include "qcoreapplication.h"
 
+#include <QtCore/qpointer.h>
+
 #include <algorithm>
 #include <memory>
 
@@ -87,7 +89,7 @@ void QThreadPoolThread::run()
             if (manager->queue.isEmpty())
                 break;
 
-            QueuePage *page = manager->queue.first();
+            QueuePage *page = manager->queue.constFirst();
             r = page->pop();
 
             if (page->isFinished()) {
@@ -210,7 +212,7 @@ void QThreadPoolPrivate::tryToStartMoreThreads()
 {
     // try to push tasks on the queue to any available threads
     while (!queue.isEmpty()) {
-        QueuePage *page = queue.first();
+        QueuePage *page = queue.constFirst();
         if (!tryStart(page->first()))
             break;
 
@@ -517,20 +519,21 @@ void QThreadPool::start(QRunnable *runnable, int priority)
 }
 
 /*!
+    \fn template<typename Callable, QRunnable::if_callable<Callable>> void QThreadPool::start(Callable &&callableToRun, int priority)
     \overload
     \since 5.15
 
-    Reserves a thread and uses it to run \a functionToRun, unless this thread will
+    Reserves a thread and uses it to run \a callableToRun, unless this thread will
     make the current thread count exceed maxThreadCount().  In that case,
-    \a functionToRun is added to a run queue instead. The \a priority argument can
+    \a callableToRun is added to a run queue instead. The \a priority argument can
     be used to control the run queue's order of execution.
+
+    \note This function participates in overload resolution only if \c Callable
+    is a function or function object which can be called with zero arguments.
+
+    \note In Qt version prior to 6.6, this function took std::function<void()>,
+    and therefore couldn't handle move-only callables.
 */
-void QThreadPool::start(std::function<void()> functionToRun, int priority)
-{
-    if (!functionToRun)
-        return;
-    start(QRunnable::create(std::move(functionToRun)), priority);
-}
 
 /*!
     Attempts to reserve a thread to run \a runnable.
@@ -562,30 +565,21 @@ bool QThreadPool::tryStart(QRunnable *runnable)
 }
 
 /*!
+    \fn template<typename Callable, QRunnable::if_callable<Callable>> bool QThreadPool::tryStart(Callable &&callableToRun)
     \overload
     \since 5.15
-    Attempts to reserve a thread to run \a functionToRun.
+    Attempts to reserve a thread to run \a callableToRun.
 
     If no threads are available at the time of calling, then this function
-    does nothing and returns \c false.  Otherwise, \a functionToRun is run immediately
+    does nothing and returns \c false.  Otherwise, \a callableToRun is run immediately
     using one available thread and this function returns \c true.
-*/
-bool QThreadPool::tryStart(std::function<void()> functionToRun)
-{
-    if (!functionToRun)
-        return false;
 
-    Q_D(QThreadPool);
-    QMutexLocker locker(&d->mutex);
-    if (!d->allThreads.isEmpty() && d->areAllThreadsActive())
-        return false;
+    \note This function participates in overload resolution only if \c Callable
+    is a function or function object which can be called with zero arguments.
 
-    QRunnable *runnable = QRunnable::create(std::move(functionToRun));
-    if (d->tryStart(runnable))
-        return true;
-    delete runnable;
-    return false;
-}
+    \note In Qt version prior to 6.6, this function took std::function<void()>,
+    and therefore couldn't handle move-only callables.
+*/
 
 /*! \property QThreadPool::expiryTimeout
     \brief the thread expiry timeout value in milliseconds.
@@ -799,19 +793,19 @@ void QThreadPool::startOnReservedThread(QRunnable *runnable)
 }
 
 /*!
+    \fn template<typename Callable, QRunnable::if_callable<Callable>> void QThreadPool::startOnReservedThread(Callable &&callableToRun)
     \overload
     \since 6.3
 
     Releases a thread previously reserved with reserveThread() and uses it
-    to run \a functionToRun.
-*/
-void QThreadPool::startOnReservedThread(std::function<void()> functionToRun)
-{
-    if (!functionToRun)
-        return releaseThread();
+    to run \a callableToRun.
 
-    startOnReservedThread(QRunnable::create(std::move(functionToRun)));
-}
+    \note This function participates in overload resolution only if \c Callable
+    is a function or function object which can be called with zero arguments.
+
+    \note In Qt version prior to 6.6, this function took std::function<void()>,
+    and therefore couldn't handle move-only callables.
+*/
 
 /*!
     Waits up to \a msecs milliseconds for all threads to exit and removes all