SFINAE out the new-style connect() overloads for const char*
functions.
Before, we detected the problem in the body of connect(), by failing
the static_assert for signal/slot argument compatibility, but that's
too late. We don't want to select that overload at all, because we
want that decltype(QObject::connect(QAction*, &QAction::triggered,
QObject*, SLOT(something())) SFINAEs instead of returning
QMetaObject::Connect, because then all the classes that provide
convenience new-style connect syntax by wrapping the
QObject::connect() call can just use that decltype() to accept
anything that will succeed in the wrapped connect() call instead of
manually trying (and failing) to provide proper overloads themselves.
[ChangeLog][QtCore][Potentially Source-Incompatible Changes]
QObject::connect(sender, pointer-to-member, [receiver, ], SLOT(~~~))
is now SFINAEd out instead of triggering a static_assert(). That means
it is now possible to use Expression SFINAE
(decltype(QObject::connect(<sender>, <signal>,
std::declval<Args>()...) to properly wrap new-style QObject::connect()
calls with a single wrapper function, greatly simplifying the
implementation, incl. passing Qt::ConnectionType arguments. For more
information on how to use this in your own code, see the sources of
QWidget::addAction().
Change-Id: I4052a49eacd63a432a9648a667adc435744a633d
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
3552821551