moc: Don't link to inexistent parent staticMetaObject

Contrarily to Q_OBJECTs, Q_GADGETs are not guaranteed to
descend from a Q_GADGET. Here, we ensure that if the first
superclass is a Q_GADGET, then the derived class will be
treated as one. This allows gaps in the Q_GADGET hierarchy
while preventing from trying to link to the inexistent
staticMetaObject if there's no such ancestor.

Change-Id: If10fb952e23655102a425bb18fe8babaf447a47f
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@theqtcompany.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/tests/auto/tools/moc/tst_moc.cpp b/tests/auto/tools/moc/tst_moc.cpp
index d67b3e011a..3117bcd09a 100644
--- a/tests/auto/tools/moc/tst_moc.cpp
+++ b/tests/auto/tools/moc/tst_moc.cpp
@@ -72,6 +72,9 @@
 #include "related-metaobjects-in-gadget.h"
 #include "related-metaobjects-name-conflict.h"
 
+#include "non-gadget-parent-class.h"
+#include "grand-parent-gadget-class.h"
+
 QT_USE_NAMESPACE
 
 template <bool b> struct QTBUG_31218 {};
@@ -574,6 +577,7 @@ private slots:
     void relatedMetaObjectsNameConflict();
     void strignLiteralsInMacroExtension();
     void veryLongStringData();
+    void gadgetHierarchy();
 
 signals:
     void sigWithUnsignedArg(unsigned foo);
@@ -3379,6 +3383,12 @@ void tst_Moc::veryLongStringData()
     QCOMPARE(strlen(mobj->classInfo(3).value()), static_cast<size_t>(1));
 }
 
+void tst_Moc::gadgetHierarchy()
+{
+    QCOMPARE(NonGadgetParent::Derived::staticMetaObject.superClass(), static_cast<const QMetaObject*>(Q_NULLPTR));
+    QCOMPARE(GrandParentGadget::DerivedGadget::staticMetaObject.superClass(), &GrandParentGadget::BaseGadget::staticMetaObject);
+}
+
 QTEST_MAIN(tst_Moc)
 
 // the generated code must compile with QT_NO_KEYWORDS