If it is attempted to connected a signature for a function that takes a constant reference of a template type, and both the const and the reference is indicated at the end of the signature, Qt will fail to find the signal/slot. The moc tool will also generate incompatible signatures when it parses signatures with templates where the const-ref is at the end of the type signature.

Example:

The following works, the signature is correctly normalized:
connect(myGraphicsScene, SIGNAL(changed(const QList<QRectF> &)), someObject, SLOT(someSlot()))

The following also works, the signature is correctly normalized:
connect(myGraphicsScene, SIGNAL(sceneRectChanged(QRectF const &)), someObject, SLOT(someSlot()))

The following does not work:
connect(myGraphicsScene, SIGNAL(changed(QList<QRectF> const &)), someObject, SLOT(someSlot()))

You will get an error saying "No such signal 'changed(QList<QRectF>const&)'" because Qt has not removed the const-ref specifier.

I believe the two syntaxes (const before and after the type) should be equivalent in this case.

Also, maybe an even bigger issue: If you specify e.g. a signal as
void mySignal(QList<QRectF> const &)

then this will not be normalized in the meta object, so if you try to connect it to a slot declared as:
void mySlot(const QList<QRectF> &)

the connection will fail as Qt will not recognize the two type signatures as equivalent.