Fix QMetaMethod::invoke and automatic type registration

This was simply not working for two reasons:
 - The index passed to QMetaObject::metacall was not right (there was an offset
   because of the return type)
 - If the registration succeeded, the arguments were not even initialized.

The tests in tst_moc always called QMetaMethod::parameterType before calling invoke,
which was properly registering the type. So this was not seen in the tests before.

[ChangeLog][QtCore][QMetaMethod] Fixed crash in invoke() with QueuedConnection and
types whose metatype gets automatically registered.

Task-number: QTBUG-60185
Change-Id: I4247628484214fba0a8acc1813ed8f112f59c888
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 7 insertions, 5 deletions

diff --git a/src/corelib/kernel/qmetaobject.cpp b/src/corelib/kernel/qmetaobject.cpp
index 2e0dd8e5d2..a8003f7e46 100644
--- a/src/corelib/kernel/qmetaobject.cpp
+++ b/src/corelib/kernel/qmetaobject.cpp
@@ -2241,12 +2241,10 @@ bool QMetaMethod::invoke(QObject *object,
 
         for (int i = 1; i < paramCount; ++i) {
             types[i] = QMetaType::type(typeNames[i]);
-            if (types[i] != QMetaType::UnknownType) {
-                args[i] = QMetaType::create(types[i], param[i]);
-                ++nargs;
-            } else if (param[i]) {
+            if (types[i] == QMetaType::UnknownType && param[i]) {
                 // Try to register the type and try again before reporting an error.
-                void *argv[] = { &types[i], &i };
+                int index = nargs - 1;
+                void *argv[] = { &types[i], &index };
                 QMetaObject::metacall(object, QMetaObject::RegisterMethodArgumentMetaType,
                                       idx_relative + idx_offset, argv);
                 if (types[i] == -1) {
@@ -2261,6 +2259,10 @@ bool QMetaMethod::invoke(QObject *object,
                     return false;
                 }
             }
+            if (types[i] != QMetaType::UnknownType) {
+                args[i] = QMetaType::create(types[i], param[i]);
+                ++nargs;
+            }
         }
 
         QCoreApplication::postEvent(object, new QMetaCallEvent(idx_offset, idx_relative, callFunction,