diff options
author | Marc Mutz <marc.mutz@qt.io> | 2023-02-02 09:05:09 +0100 |
---|---|---|
committer | Marc Mutz <marc.mutz@qt.io> | 2023-02-02 23:45:30 +0100 |
commit | c53fdcb5ee15c309ba68717fa6564dc1ff4b8618 (patch) | |
tree | cb389b541fc32bca6d46997c3f18da47475916a8 /src | |
parent | d3f8d7fd4140b269532e2daca8eb5cbfe28ed465 (diff) |
Q_APPLICATION_STATIC: add missing std::launder()
Unlike Q_GLOBAL_STATIC, a Q_APPLICATION_STATIC can be destroyed and
re-created multiple times (if QCoreApplication is, too). This means
we're basically in the std::optional case and require std::launder()
to avoid UB when the payload type has either of the following:
- a const member
- a reference member
- a vtable and different derived classes might be occupying the same
space at different times
While we can probably exclude the latter, because we always construct
the same type, PlainType, in the storage, the first two can easily
happen.
Fix by adding the missing std::launder().
As a drive-by, remove the uneeded casting (and now launder()ing) of
&storage when passing to innerFunction(), which anyway takes its
argument as void*.
Amends 81a31beeb25eaf14d5c5f42fe26aa49d6ef29bf8, which changed
Q_APPLICATION_STATIC to use inline aligned_union storage instead of
the original implementation's unique_ptr.
Pick-to: 6.5 6.4
Change-Id: I065bd33812a40195109bf11d5bc79975f2f87cd5
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Diffstat (limited to 'src')
-rw-r--r-- | src/corelib/kernel/qapplicationstatic.h | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/src/corelib/kernel/qapplicationstatic.h b/src/corelib/kernel/qapplicationstatic.h index f311da5d77..2f2cab9174 100644 --- a/src/corelib/kernel/qapplicationstatic.h +++ b/src/corelib/kernel/qapplicationstatic.h @@ -9,6 +9,8 @@ #include <QtCore/qcoreapplication.h> #include <QtCore/qglobalstatic.h> +#include <new> + QT_BEGIN_NAMESPACE namespace QtGlobalStatic { @@ -36,7 +38,7 @@ template <typename QAS> struct ApplicationHolder static PlainType *realPointer() { - return reinterpret_cast<PlainType *>(&storage); + return std::launder(reinterpret_cast<PlainType *>(&storage)); } // called from QGlobalStatic::instance() @@ -46,7 +48,7 @@ template <typename QAS> struct ApplicationHolder return realPointer(); QMutexLocker locker(&mutex); if (guard.loadRelaxed() == QtGlobalStatic::Uninitialized) { - QAS::innerFunction(realPointer()); + QAS::innerFunction(&storage); QObject::connect(QCoreApplication::instance(), &QObject::destroyed, reset); guard.storeRelaxed(QtGlobalStatic::Initialized); } |