QtTest WatchDog: fix UB (default-constructed std::atomic)

Up to C++17 inclusive, a default-constructed std::atomic object can
only be initialized using std::atomic_init(), _not_ by .store().

While it's probably not a problem in practice, it's also not much work
to call the std::atomic<T>(T) ctor in the ctor-init-list instead of
the implicit default constructor, followed by a store() in the body of
the ctor, so do that.

Amends a8a38f7caabb90113a229629c6fe463acdecd10f.

Pick-to: 6.10 6.9 6.8 6.5
Change-Id: I9ba953d1bc34fe09326554a65393b8a2deb35328
Reviewed-by: David Faure <[email protected]>

1 files changed, 1 insertions, 1 deletions

diff --git a/src/testlib/qtestcase.cpp b/src/testlib/qtestcase.cpp
index f4aa45be73e..53cc849e23c 100644
--- a/src/testlib/qtestcase.cpp
+++ b/src/testlib/qtestcase.cpp
@@ -1176,10 +1176,10 @@ class WatchDog : public QThread
 
 public:
     WatchDog()
+        : expecting{ThreadStart}
     {
         setObjectName("QtTest Watchdog"_L1);
         auto locker = qt_unique_lock(mutex);
-        expecting.store(ThreadStart, std::memory_order_relaxed);
         start();
         waitFor(locker, ThreadStart);
     }