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QArrayDataOps: fix FP equality comparison

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We cannot use memcmp() for that, as it incorrectly results in two
NaN values being equal.
Simply replace the whole self-written algorithm with std::equal(),
as it's doing the same thing, but lets the compiler decide when
to do the optimizations.

Amends db89349bdba2fcc03b2f7e2d23f549a9ec5dc0e3.

[ChangeLog][QtCore][QList] Fixed a bug when two QLists holding NaN
values were considered to be equal.

Fixes: QTBUG-127473
Pick-to: 6.7 6.5 6.2
Change-Id: If7e77549b4cbeb96711893d14344b9e0a40c1a87
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit cb3faeba3d9411ba82c311751bd7de36d0fec939)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Ivan Solovev 2024-07-23 15:49:54 +02:00 committed by Qt Cherry-pick Bot
parent 7a31702345
commit f53074c747
2 changed files with 29 additions and 26 deletions
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27
src/corelib/tools/qarraydataops.h
View File

@ -272,23 +272,8 @@ public:
bool compare(const T *begin1, const T *begin2, size_t n) const
{
// only use memcmp for fundamental types or pointers.
// Other types could have padding in the data structure or custom comparison
// operators that would break the comparison using memcmp
if constexpr (QArrayDataPointer<T>::pass_parameter_by_value) {
return ::memcmp(begin1, begin2, n * sizeof(T)) == 0;
} else {
const T *end1 = begin1 + n;
while (begin1 != end1) {
if (*begin1 == *begin2) {
++begin1;
++begin2;
} else {
return false;
}
}
return true;
}
return std::equal(begin1, end1, begin2);
}
void reallocate(qsizetype alloc, QArrayData::AllocationOption option)
@ -665,15 +650,7 @@ public:
bool compare(const T *begin1, const T *begin2, size_t n) const
{
const T *end1 = begin1 + n;
while (begin1 != end1) {
if (*begin1 == *begin2) {
++begin1;
++begin2;
} else {
return false;
}
}
return true;
return std::equal(begin1, end1, begin2);
}
};

26
tests/auto/corelib/tools/containerapisymmetry/tst_containerapisymmetry.cpp
View File

@ -429,6 +429,21 @@ private Q_SLOTS:
void keyValueRange_QMultiMap() { keyValueRange_impl<QMultiMap<int, int>>(); }
void keyValueRange_QHash() { keyValueRange_impl<QHash<int, int>>(); }
void keyValueRange_QMultiHash() { keyValueRange_impl<QMultiHash<int, int>>(); }
private:
template <typename Container>
void opEqNaN_impl() const;
private Q_SLOTS:
void opEqNaN_QList_Float() { opEqNaN_impl<QList<float>>(); }
void opEqNaN_QList_Float16() { opEqNaN_impl<QList<qfloat16>>(); }
void opEqNaN_QList_Double() { opEqNaN_impl<QList<double>>(); }
void opEqNaN_QVarLengthArray_Float() { opEqNaN_impl<QVarLengthArray<float>>(); }
void opEqNaN_QVarLengthArray_Float16() { opEqNaN_impl<QVarLengthArray<qfloat16>>(); }
void opEqNaN_QVarLengthArray_Double() { opEqNaN_impl<QVarLengthArray<double>>(); }
void opEqNaN_QSet_Float() { opEqNaN_impl<QSet<float>>(); }
void opEqNaN_QSet_Float16() { opEqNaN_impl<QSet<qfloat16>>(); }
void opEqNaN_QSet_Double() { opEqNaN_impl<QSet<double>>(); }
};
void tst_ContainerApiSymmetry::init()
@ -1263,5 +1278,16 @@ void tst_ContainerApiSymmetry::keyValueRange_impl() const
QVERIFY(verify(values, COUNT, 2));
}
template<typename Container>
void tst_ContainerApiSymmetry::opEqNaN_impl() const
{
using V = typename Container::value_type;
static_assert(std::is_floating_point_v<V> || std::is_same_v<V, qfloat16>);
const Container lhs {std::numeric_limits<V>::quiet_NaN()};
const Container rhs {std::numeric_limits<V>::quiet_NaN()};
QCOMPARE_NE(lhs, rhs);
}
QTEST_APPLESS_MAIN(tst_ContainerApiSymmetry)
#include "tst_containerapisymmetry.moc"