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authorThiago Macieira <thiago.macieira@intel.com>2016-01-03 11:27:09 -0200
committerThiago Macieira <thiago.macieira@intel.com>2016-01-12 19:25:42 +0000
commit70092c9a47840e1ca7606b90075b364c69876656 (patch)
tree29f115b72a141aeaed0c1d1f5fa8e92bd3350f8d
parent9f09fed72f87c9379fcbfd51cd6463b5c470814f (diff)
Fix GCC 6 warning about placement-new operator on too little space
GCC 6 is able to detect when you use a placement new of an object in a space that is too small to contain it. qvariant_p.h: In instantiation of ‘void v_construct(QVariant::Private*, const T&) [with T = QRectF]’: qvariant_p.h:142:9: error: placement new constructing an object of type ‘QRectF’ and size ‘32’ in a region of type ‘void*’ and size ‘8’ [-Werror=placement-new] new (&x->data.ptr) T(t); ^~~~~~~~~~~~~~~~~~~~~~~ This happens even for the false branch of a constant expression (the enum). So split the v_construct function in two pairs, one pair for being able to use the internal space and one pair not so. Change-Id: Ibc83b9f7e3bc4962ae35ffff1425ed898f279dea Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com> Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@theqtcompany.com>
-rw-r--r--src/corelib/kernel/qvariant_p.h55
1 files changed, 37 insertions, 18 deletions
diff --git a/src/corelib/kernel/qvariant_p.h b/src/corelib/kernel/qvariant_p.h
index 4a7df1ad8d..337e1406ec 100644
--- a/src/corelib/kernel/qvariant_p.h
+++ b/src/corelib/kernel/qvariant_p.h
@@ -60,6 +60,7 @@ struct QVariantIntegrator
{
static const bool CanUseInternalSpace = sizeof(T) <= sizeof(QVariant::Private::Data)
&& ((QTypeInfoQuery<T>::isRelocatable) || Q_IS_ENUM(T));
+ typedef QtPrivate::integral_constant<bool, CanUseInternalSpace> CanUseInternalSpace_t;
};
Q_STATIC_ASSERT(QVariantIntegrator<double>::CanUseInternalSpace);
Q_STATIC_ASSERT(QVariantIntegrator<long int>::CanUseInternalSpace);
@@ -110,31 +111,49 @@ private:
T m_t;
};
-// constructs a new variant if copy is 0, otherwise copy-constructs
template <class T>
-inline void v_construct(QVariant::Private *x, const void *copy, T * = 0)
+inline void v_construct_helper(QVariant::Private *x, const T &t, QtPrivate::true_type)
{
- if (!QVariantIntegrator<T>::CanUseInternalSpace) {
- x->data.shared = copy ? new QVariantPrivateSharedEx<T>(*static_cast<const T *>(copy))
- : new QVariantPrivateSharedEx<T>;
- } else {
- if (copy)
- new (&x->data.ptr) T(*static_cast<const T *>(copy));
- else
- new (&x->data.ptr) T();
- }
- x->is_shared = !QVariantIntegrator<T>::CanUseInternalSpace;
+ new (&x->data) T(t);
+ x->is_shared = false;
+}
+
+template <class T>
+inline void v_construct_helper(QVariant::Private *x, const T &t, QtPrivate::false_type)
+{
+ x->data.shared = new QVariantPrivateSharedEx<T>(t);
+ x->is_shared = true;
+}
+
+template <class T>
+inline void v_construct_helper(QVariant::Private *x, QtPrivate::true_type)
+{
+ new (&x->data) T();
+ x->is_shared = false;
+}
+
+template <class T>
+inline void v_construct_helper(QVariant::Private *x, QtPrivate::false_type)
+{
+ x->data.shared = new QVariantPrivateSharedEx<T>;
+ x->is_shared = true;
}
template <class T>
inline void v_construct(QVariant::Private *x, const T &t)
{
- if (!QVariantIntegrator<T>::CanUseInternalSpace) {
- x->data.shared = new QVariantPrivateSharedEx<T>(t);
- } else {
- new (&x->data.ptr) T(t);
- }
- x->is_shared = !QVariantIntegrator<T>::CanUseInternalSpace;
+ // dispatch
+ v_construct_helper(x, t, typename QVariantIntegrator<T>::CanUseInternalSpace_t());
+}
+
+// constructs a new variant if copy is 0, otherwise copy-constructs
+template <class T>
+inline void v_construct(QVariant::Private *x, const void *copy, T * = 0)
+{
+ if (copy)
+ v_construct<T>(x, *static_cast<const T *>(copy));
+ else
+ v_construct_helper<T>(x, typename QVariantIntegrator<T>::CanUseInternalSpace_t());
}
// deletes the internal structures