Fix the ref-counting for the std::function version of tryStart()

The refcount isn't used, but is asserted in debug mode.

Fixes: QTBUG-109732
Change-Id: I5c4f402ca2a15b92f318896de994f3bfedf4eb87
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/corelib/thread/qthreadpool.cpp b/src/corelib/thread/qthreadpool.cpp
index 7eb1e1fbce..a627b0fb50 100644
--- a/src/corelib/thread/qthreadpool.cpp
+++ b/src/corelib/thread/qthreadpool.cpp
@@ -602,8 +602,12 @@ bool QThreadPool::tryStart(std::function<void()> functionToRun)
         return false;
 
     QRunnable *runnable = QRunnable::create(std::move(functionToRun));
+    Q_ASSERT(runnable->ref == 0);
+    ++runnable->ref;
     if (d->tryStart(runnable))
         return true;
+    --runnable->ref;
+    Q_ASSERT(runnable->ref == 0);
     delete runnable;
     return false;
 }