QMetaType: don't create a registry just to query its emptiness

The function-call operator of QGlobalStatic creates the payload object
unless is has already been deleted. When performing read-only
operations on the payload object, it's better to use
QGlobalStatic::exists() + the dereference operator instead, because
that prevents the creation of the payload just to find it empty.

Pick-to: 6.3
Change-Id: I367add516520d076412cbbc542ee7a3b6ea45c14
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

1 files changed, 4 insertions, 3 deletions

diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index c0bc82ed29..cd71805e12 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -2580,7 +2580,8 @@ static inline int qMetaTypeStaticType(const char *typeName, int length)
 */
 static int qMetaTypeCustomType_unlocked(const char *typeName, int length)
 {
-    if (auto reg = customTypeRegistry()) {
+    if (customTypeRegistry.exists()) {
+        auto reg = &*customTypeRegistry;
 #if QT_CONFIG(thread)
         Q_ASSERT(!reg->lock.tryLockForWrite());
 #endif
@@ -2980,8 +2981,8 @@ static const QtPrivate::QMetaTypeInterface *interfaceForType(int typeId)
 {
     const QtPrivate::QMetaTypeInterface *iface = nullptr;
     if (typeId >= QMetaType::User) {
-        if (auto reg = customTypeRegistry())
-            iface = reg->getCustomType(typeId);
+        if (customTypeRegistry.exists())
+            iface = customTypeRegistry->getCustomType(typeId);
     } else {
         if (auto moduleHelper = qModuleHelperForType(typeId))
             iface = moduleHelper->interfaceForType(typeId);