QObject::connect tries to determine if the arguments are registered
metatypes. This used to work even for arguments that were forward
declared. But now, the metatype system tries to call
QtPrivate::IsQEnumHelper<T>::Value to know if it is registered.
That fails on gcc if T is forward declared.
Apparently gcc needs to know the full type of T to pass it in the
ellipsis function, even within a sizeof expression.
So change the ellipsis expression to a template one.
Task-number: QTBUG-44496
Change-Id: I7fa07bd3cde470b134c2ec53b0d581333d16a6f1
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
7c77013c7f