diff options
author | Giuseppe D'Angelo <giuseppe.dangelo@kdab.com> | 2021-08-26 17:18:40 +0200 |
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committer | Giuseppe D'Angelo <giuseppe.dangelo@kdab.com> | 2021-08-27 15:45:25 +0200 |
commit | 7d4d47de7049ba52726071d4d2ba03fc014aa48d (patch) | |
tree | 2f97c146dd7b27febc4acdb6944f2dfdffa08b6b /src | |
parent | c9830c2fb902f26dc8b2df61dfadc2d7a7d2b30e (diff) |
QObject::connect(): fail to connect to a functor if UniqueConnection is passed
The connect() documentation makes it clear that UniqueConnection does
not work with free functions / function objects and the like; only with
actual PMFs. Rather than silently *ignoring* the flag, be vocal about its
presence by warning, and make the connection fail (as the user has
passed an illegal argument).
[ChangeLog][QtCore][QObject] QObject::connect() now will refuse to
connect a signal to a free function / function object if UniqueConnection
is passed. Note that UniqueConnection has never worked for such
connections -- the flag was simply ignored, and they were established
multiple times. Now, the flag is not ignored and results in a connection
failure (as well as a runtime warning by Qt).
Change-Id: I6509667018c74f9bd24910cde0a1b16c5f84f064
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: MÃ¥rten Nordheim <marten.nordheim@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'src')
-rw-r--r-- | src/corelib/kernel/qobject.cpp | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp index d524fd4305..582073a3b2 100644 --- a/src/corelib/kernel/qobject.cpp +++ b/src/corelib/kernel/qobject.cpp @@ -4974,6 +4974,19 @@ QMetaObject::Connection QObject::connectImpl(const QObject *sender, void **signa return QObjectPrivate::connectImpl(sender, signal_index, receiver, slot, slotObj, type, types, senderMetaObject); } +static void connectWarning(const QObject *sender, + const QMetaObject *senderMetaObject, + const QObject *receiver, + const char *message) +{ + const char *senderString = sender ? sender->metaObject()->className() + : senderMetaObject ? senderMetaObject->className() + : "Unknown"; + const char *receiverString = receiver ? receiver->metaObject()->className() + : "Unknown"; + qCWarning(lcConnect, "QObject::connect(%s, %s): %s", senderString, receiverString, message); +} + /*! \internal @@ -4986,18 +4999,24 @@ QMetaObject::Connection QObjectPrivate::connectImpl(const QObject *sender, int s QtPrivate::QSlotObjectBase *slotObj, int type, const int *types, const QMetaObject *senderMetaObject) { - if (!sender || !receiver || !slotObj || !senderMetaObject) { - const char *senderString = sender ? sender->metaObject()->className() - : senderMetaObject ? senderMetaObject->className() - : "Unknown"; - const char *receiverString = receiver ? receiver->metaObject()->className() - : "Unknown"; - qCWarning(lcConnect, "QObject::connect(%s, %s): invalid nullptr parameter", senderString, receiverString); + auto connectFailureGuard = qScopeGuard([&]() + { if (slotObj) slotObj->destroyIfLastRef(); + }); + + if (!sender || !receiver || !slotObj || !senderMetaObject) { + connectWarning(sender, senderMetaObject, receiver, "invalid nullptr parameter"); return QMetaObject::Connection(); } + if (type & Qt::UniqueConnection && !slot) { + connectWarning(sender, senderMetaObject, receiver, "unique connections require a pointer to member function of a QObject subclass"); + return QMetaObject::Connection(); + } + + connectFailureGuard.dismiss(); + QObject *s = const_cast<QObject *>(sender); QObject *r = const_cast<QObject *>(receiver); |