3 files changed, 29 insertions, 34 deletions
diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index 795cc531114..b48922daeab 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -17,7 +17,7 @@
 #include <qthread.h>
 #include "private/qthread_p.h"
 #if QT_CONFIG(thread)
-#include <qsemaphore.h>
+#include "private/qlatch_p.h"
 #endif
 
 // for normalizeTypeInternal
@@ -1748,9 +1748,9 @@ bool QMetaObject::invokeMethodImpl(QObject *object, QtPrivate::QSlotObjectBase *
         if (receiverInSameThread)
             qWarning("QMetaObject::invokeMethod: Dead lock detected");
 
-        QSemaphore semaphore;
-        QCoreApplication::postEvent(object, new QMetaCallEvent(std::move(slot), nullptr, -1, argv, &semaphore));
-        semaphore.acquire();
+        QLatch latch(1);
+        QCoreApplication::postEvent(object, new QMetaCallEvent(std::move(slot), nullptr, -1, argv, &latch));
+        latch.wait();
 #endif // QT_CONFIG(thread)
     } else {
         qWarning("QMetaObject::invokeMethod: Unknown connection type");
@@ -2922,10 +2922,10 @@ auto QMetaMethodInvoker::invokeImpl(QMetaMethod self, void *target,
             return InvokeFailReason::DeadLockDetected;
         }
 
-        QSemaphore semaphore;
+        QLatch latch(1);
         QCoreApplication::postEvent(object, new QMetaCallEvent(idx_offset, idx_relative, callFunction,
-                                                        nullptr, -1, param, &semaphore));
-        semaphore.acquire();
+                                                               nullptr, -1, param, &latch));
+        latch.wait();
 #endif // QT_CONFIG(thread)
     }
     return {};
diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 38ded8117c0..888c71f5a49 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -27,7 +27,7 @@
 #include <qscopeguard.h>
 #include <qset.h>
 #if QT_CONFIG(thread)
-#include <qsemaphore.h>
+#include <private/qlatch_p.h>
 #endif
 
 #include <private/qorderedmutexlocker_p.h>
@@ -476,8 +476,8 @@ void QObjectPrivate::reinitBindingStorageAfterThreadMove()
 QAbstractMetaCallEvent::~QAbstractMetaCallEvent()
 {
 #if QT_CONFIG(thread)
-    if (semaphore_)
-        semaphore_->release();
+    if (latch)
+        latch->countDown();
 #endif
 }
 
@@ -506,8 +506,8 @@ inline void QMetaCallEvent::allocArgs()
 QMetaCallEvent::QMetaCallEvent(ushort method_offset, ushort method_relative,
                                QObjectPrivate::StaticMetaCallFunction callFunction,
                                const QObject *sender, int signalId,
-                               void **args, QSemaphore *semaphore)
-    : QAbstractMetaCallEvent(sender, signalId, semaphore),
+                               void **args, QLatch *latch)
+    : QAbstractMetaCallEvent(sender, signalId, latch),
       d({nullptr, args, callFunction, 0, method_offset, method_relative}),
       prealloc_()
 {
@@ -521,8 +521,8 @@ QMetaCallEvent::QMetaCallEvent(ushort method_offset, ushort method_relative,
  */
 QMetaCallEvent::QMetaCallEvent(QtPrivate::QSlotObjectBase *slotO,
                                const QObject *sender, int signalId,
-                               void **args, QSemaphore *semaphore)
-    : QAbstractMetaCallEvent(sender, signalId, semaphore),
+                               void **args, QLatch *latch)
+    : QAbstractMetaCallEvent(sender, signalId, latch),
       d({QtPrivate::SlotObjUniquePtr{slotO}, args, nullptr, 0, 0, ushort(-1)}),
       prealloc_()
 {
@@ -538,8 +538,8 @@ QMetaCallEvent::QMetaCallEvent(QtPrivate::QSlotObjectBase *slotO,
  */
 QMetaCallEvent::QMetaCallEvent(QtPrivate::SlotObjUniquePtr slotO,
                                const QObject *sender, int signalId,
-                               void **args, QSemaphore *semaphore)
-    : QAbstractMetaCallEvent(sender, signalId, semaphore),
+                               void **args, QLatch *latch)
+    : QAbstractMetaCallEvent(sender, signalId, latch),
       d{std::move(slotO), args, nullptr, 0, 0, ushort(-1)},
       prealloc_()
 {
@@ -4198,18 +4198,18 @@ void doActivate(QObject *sender, int signal_index, void **argv)
                 if (c->isSingleShot && !QObjectPrivate::removeConnection(c))
                     continue;
 
-                QSemaphore semaphore;
+                QLatch latch(1);
                 {
                     QMutexLocker locker(signalSlotLock(receiver));
                     if (!c->isSingleShot && !c->receiver.loadAcquire())
                         continue;
                     QMetaCallEvent *ev = c->isSlotObject ?
-                        new QMetaCallEvent(c->slotObj, sender, signal_index, argv, &semaphore) :
+                        new QMetaCallEvent(c->slotObj, sender, signal_index, argv, &latch) :
                         new QMetaCallEvent(c->method_offset, c->method_relative, c->callFunction,
-                                           sender, signal_index, argv, &semaphore);
+                                           sender, signal_index, argv, &latch);
                     QCoreApplication::postEvent(receiver, ev);
                 }
-                semaphore.acquire();
+                latch.wait();
                 continue;
 #endif
             }
diff --git a/src/corelib/kernel/qobject_p.h b/src/corelib/kernel/qobject_p.h
index 20c454506ab..dca9c1af932 100644
--- a/src/corelib/kernel/qobject_p.h
+++ b/src/corelib/kernel/qobject_p.h
@@ -328,16 +328,13 @@ bool QObjectPrivate::disconnect(const typename QtPrivate::FunctionPointer< Func1
                           &SignalType::Object::staticMetaObject);
 }
 
-class QSemaphore;
+class QLatch;
 class Q_CORE_EXPORT QAbstractMetaCallEvent : public QEvent
 {
 public:
-    QAbstractMetaCallEvent(const QObject *sender, int signalId, QSemaphore *semaphore = nullptr)
-        : QEvent(MetaCall), signalId_(signalId), sender_(sender)
-#if QT_CONFIG(thread)
-        , semaphore_(semaphore)
-#endif
-    { Q_UNUSED(semaphore); }
+    QAbstractMetaCallEvent(const QObject *sender, int signalId, QLatch *latch = nullptr)
+        : QEvent(MetaCall), signalId_(signalId), sender_(sender), latch(latch)
+    {}
     ~QAbstractMetaCallEvent();
 
     virtual void placeMetaCall(QObject *object) = 0;
@@ -348,25 +345,23 @@ public:
 private:
     int signalId_;
     const QObject *sender_;
-#if QT_CONFIG(thread)
-    QSemaphore *semaphore_;
-#endif
+    QLatch *latch;
 };
 
 class Q_CORE_EXPORT QMetaCallEvent : public QAbstractMetaCallEvent
 {
 public:
-    // blocking queued with semaphore - args always owned by caller
+    // blocking queued with latch - args always owned by caller
     QMetaCallEvent(ushort method_offset, ushort method_relative,
                    QObjectPrivate::StaticMetaCallFunction callFunction,
                    const QObject *sender, int signalId,
-                   void **args, QSemaphore *semaphore);
+                   void **args, QLatch *latch);
     QMetaCallEvent(QtPrivate::QSlotObjectBase *slotObj,
                    const QObject *sender, int signalId,
-                   void **args, QSemaphore *semaphore);
+                   void **args, QLatch *latch);
     QMetaCallEvent(QtPrivate::SlotObjUniquePtr slotObj,
                    const QObject *sender, int signalId,
-                   void **args, QSemaphore *semaphore);
+                   void **args, QLatch *latch);
 
     // queued - args allocated by event, copied by caller
     QMetaCallEvent(ushort method_offset, ushort method_relative,