QMetaType: Support converting any QFuture<T> to QFuture<void>

QMetaType now implicitly knows how to convert any QFuture<T> to
QFuture<void> without needing to manually register a converter
function.

QtWebChannel will make use of this to transparently support QFuture<T>
return types.

[ChangeLog][QtCore][QMetaType] QMetaType now supports converting any
QFuture<T> to QFuture<void>.

Task-number: QTBUG-92903
Change-Id: Ied7e71be37c346cc3d2c274ffb0d91a6821ab4d4
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/corelib/kernel/qmetatype.h b/src/corelib/kernel/qmetatype.h
index 019a85c12a..adc4ae92d5 100644
--- a/src/corelib/kernel/qmetatype.h
+++ b/src/corelib/kernel/qmetatype.h
@@ -1092,6 +1092,14 @@ namespace QtPrivate
         static bool registerConverter() { return false; }
     };
 
+#if QT_CONFIG(future)
+    template<typename T>
+    struct MetaTypeQFutureHelper
+    {
+        static bool registerConverter() { return false; }
+    };
+#endif
+
     Q_CORE_EXPORT bool isBuiltinType(const QByteArray &type);
 } // namespace QtPrivate
 
@@ -1218,6 +1226,9 @@ int qRegisterNormalizedMetaType(const QT_PREPEND_NAMESPACE(QByteArray) &normaliz
     QtPrivate::AssociativeContainerTransformationHelper<T>::registerMutableView();
     QtPrivate::MetaTypePairHelper<T>::registerConverter();
     QtPrivate::MetaTypeSmartPointerHelper<T>::registerConverter();
+#if QT_CONFIG(future)
+    QtPrivate::MetaTypeQFutureHelper<T>::registerConverter();
+#endif
 
     if (normalizedTypeName != metaType.name())
         QMetaType::registerNormalizedTypedef(normalizedTypeName, metaType);