diff options
authorThiago Macieira <>2018-10-25 16:32:13 -0700
committerThiago Macieira <>2018-10-29 19:12:17 +0000
commit3b8075de3b3c842311c157476a85d2cf9ddff403 (patch)
parentd4e937a6280f34bc1cce8c8cea3806a741312fbc (diff)
Fix deleting of QSharedPointer internals in case QPointer loses the race
QPointer uses QWeakPointer / QSharedPointer internals in QObject and has the code to make sure two threads won't stomp on each other if both try to create a QPointer for the same QObject at the same time. The threading code was fine, but had a mistake in the clean up code for the loser thread: the QtSharedPointer::ExternalRefCountData destructor has a Q_ASSERT for the state of the reference counts. So we need to set the state correctly before calling the destructor. But we don't want to do it in case the Q_ASSERT compiled to nothing. So we use a hack that violates the Second Rule of Q_ASSERTs: don't do something with side-effects. This way, we can insert code that will only be compiled if Q_ASSERTs do something, without having to duplicate the preprocessor conditions from qglobal.h. Fixes: QTBUG-71412 Change-Id: I1bd327aeaf73421a8ec5fffd1560fdfc8b73b70c Reviewed-by: Romain Pokrzywka <> Reviewed-by: Jędrzej Nowacki <>
1 files changed, 3 insertions, 0 deletions
diff --git a/src/corelib/tools/qsharedpointer.cpp b/src/corelib/tools/qsharedpointer.cpp
index 2d5fd2a00e..65616e2abb 100644
--- a/src/corelib/tools/qsharedpointer.cpp
+++ b/src/corelib/tools/qsharedpointer.cpp
@@ -1466,6 +1466,9 @@ QtSharedPointer::ExternalRefCountData *QtSharedPointer::ExternalRefCountData::ge
x->; // the QWeakPointer that called us plus the QObject itself
if (!d->sharedRefcount.testAndSetRelease(0, x)) {
+ // ~ExternalRefCountData has a Q_ASSERT, so we use this trick to
+ // only execute this if Q_ASSERTs are enabled
+ Q_ASSERT((x->, true));
delete x;
x = d->sharedRefcount.loadAcquire();