Pacify MSVC compiler incorrectly warning about unused variable

Under some circumstances, MSVC seems to complain about SlotArgumentCount
being unused

  qobject.h(210): warning C4189: 'SlotArgumentCount': local variable is
  initialized but not referenced
  note: see reference to function template instantiation
  'QMetaObject::Connection QObject::connect<void(__cdecl QAction::* )(bool),
  main::<lambda_1>>(const QAction *,Func1,
    const QtPrivate::ContextTypeForFunctor<main::<lambda_1>,void>::ContextType *,
    Func2 &&,Qt::ConnectionType)' being compiled

This is nonsense, as SlotArgumentCount is used in the next line, to
construct the list of signal arguments, but the workaround to declare
the variable as [[maybe_unused]] is trivial.

Add a connect statement to the test case that creates such a connection.
This does not produce any warning with or without the attribute (and if
it did, the build would fail for CI configuratinos setting -Werror).

Pick-to: 6.6
Fixes: QTBUG-114781
Change-Id: I4ee6f7d57c2836ef3dd9741d037d48181af2cdec
Reviewed-by: Marc Mutz <marc.mutz@qt.io>

1 files changed, 1 insertions, 0 deletions

diff --git a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
index 73b77932ce..31345cc333 100644
--- a/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
+++ b/tests/auto/corelib/kernel/qobject/tst_qobject.cpp
@@ -6075,6 +6075,7 @@ void tst_QObject::connectFunctorArgDifference()
 
     connect(&timer, &QTimer::timeout, [=](){});
     connect(&timer, &QTimer::objectNameChanged, [=](const QString &){});
+    connect(&timer, &QTimer::objectNameChanged, this, [](){});
     connect(qApp, &QCoreApplication::aboutToQuit, [=](){});
 
     connect(&timer, &QTimer::objectNameChanged, [=](){});