QMetaTypeId2::IsBuiltIn: (new) template meta-function to check for built-in types

This allows to check whether QMetaTypeId2::MetaType exists, and can help
turn run-time into compile-time expressions, even without constexpr support,
or in situations where constexpr can't be used (because you can't overload
on it). This was designed for the QMetaType::registerConversion feature,
but it's much more widely applicable.

Change-Id: Iafa04add04bcb531b3f7fe3e751c7e91ee6a3bc0
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@nokia.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/tests/auto/widgets/kernel/qwidgetmetatype/tst_qwidgetmetatype.cpp b/tests/auto/widgets/kernel/qwidgetmetatype/tst_qwidgetmetatype.cpp
index 9d2fd149f4..f92a4fd5cd 100644
--- a/tests/auto/widgets/kernel/qwidgetmetatype/tst_qwidgetmetatype.cpp
+++ b/tests/auto/widgets/kernel/qwidgetmetatype/tst_qwidgetmetatype.cpp
@@ -67,6 +67,12 @@ public:
   }
 };
 
+Q_STATIC_ASSERT(( QMetaTypeId2<QSizePolicy>::IsBuiltIn));
+Q_STATIC_ASSERT(( QMetaTypeId2<QWidget*>::IsBuiltIn));
+Q_STATIC_ASSERT((!QMetaTypeId2<QList<QSizePolicy> >::IsBuiltIn));
+Q_STATIC_ASSERT((!QMetaTypeId2<QMap<QString,QSizePolicy> >::IsBuiltIn));
+
+
 void tst_QWidgetMetaType::metaObject()
 {
     QCOMPARE(QMetaType::metaObjectForType(QMetaType::QWidgetStar), &QWidget::staticMetaObject);