QVariant: attempt to work around an ICE on linux-arm-gnueabi-g++ (Ubuntu 11.10) with constexpr QSizePolicy

This is the error:

  src/corelib/kernel/qvariant_p.h: In constructor ‘QVariantPrivateSharedEx<T>::QVariantPrivateSharedEx() [with T = QSizePolicy]’:
  src/corelib/kernel/qvariant_p.h:107:61: internal compiler error: in gimplify_init_ctor_eval, at gimplify.c:3560

There are two things fishy in this file:

1. Use of the unnamed namespace in a file that gets included
   in different libraries. While not technically undefined
   behavior, it may become so when used in the implementation,
   which it is.
2. Missing explicit initialization of a member of
   QVariantPrivateSharedEx. This is just a wild guess, because
   the ICE happens in that line. That class itself is quite
   smelly, because the address of an object is taken before
   the lifetime of the object begins. A fix would be to store
   the object in a wrapper class from which QVPSEx inherits
   _first_, but then a cast from QVPSEx to QVariant::PrivateShared
   would require pointer adjustments, and I didn't look through
   all the code to determine whether that would be an issue.
   Having been bitten by this sometime ago:
    https://marcmutz.wordpress.com/private-practice/private-practice-taming-templates/#edit-20111128
   I opted to do these easy changes first to see whether they
   already fix the ICE.

Change-Id: Ic15fd928b3dff2318c425c915b2dab5e54254d71
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Marc Mutz 2015-01-15 14:58:06 +01:00 committed by Thiago Macieira
parent 47f99cacc4
commit 49057a1eab

View File

@ -54,7 +54,6 @@
QT_BEGIN_NAMESPACE
namespace {
template<typename T>
struct QVariantIntegrator
{
@ -64,7 +63,6 @@ struct QVariantIntegrator
Q_STATIC_ASSERT(QVariantIntegrator<double>::CanUseInternalSpace);
Q_STATIC_ASSERT(QVariantIntegrator<long int>::CanUseInternalSpace);
Q_STATIC_ASSERT(QVariantIntegrator<qulonglong>::CanUseInternalSpace);
} // namespace
#ifdef Q_CC_SUN // Sun CC picks the wrong overload, so introduce awful hack
@ -104,7 +102,7 @@ inline T *v_cast(QVariant::Private *d, T * = 0)
template <class T> class QVariantPrivateSharedEx : public QVariant::PrivateShared
{
public:
QVariantPrivateSharedEx() : QVariant::PrivateShared(&m_t) { }
QVariantPrivateSharedEx() : QVariant::PrivateShared(&m_t), m_t() { }
QVariantPrivateSharedEx(const T&t) : QVariant::PrivateShared(&m_t), m_t(t) { }
private: