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QDebug: do not trigger integer overflow when printing a QRect

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QRect::width() and height() may overflow: they're only safe to call
when right-left+1 (or bottom-top+1) is representable by an `int`.
Therefore, avoiding calling them from QDebug, which is supposed to
"always work" (otherwise, it's not of great debugging help...).

QRectF does not have this issue as it stores the width directly.

Change-Id: I438dbacae42c17730afb92f05d16e3eebb161255
Pick-to: 6.8 6.5
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 0f336500a0add3e3a8bb31c5cc605e5e13e23833)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Giuseppe D'Angelo 2025-01-27 17:36:28 +01:00 committed by Qt Cherry-pick Bot
parent abf6c88a86
commit 8232c837b0
2 changed files with 41 additions and 1 deletions
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12
src/corelib/io/qdebug_p.h
View File

@ -23,6 +23,8 @@
QT_BEGIN_NAMESPACE
class QRect;
namespace QtDebugUtils {
Q_CORE_EXPORT QByteArray toPrintable(const char *data, qint64 len, qsizetype maxSize);
@ -44,7 +46,15 @@ static inline void formatQSize(QDebug &debug, const Size &size)
template <class Rect>
static inline void formatQRect(QDebug &debug, const Rect &rect)
{
debug << rect.x() << ',' << rect.y() << ' ' << rect.width() << 'x' << rect.height();
debug << rect.x() << ',' << rect.y() << ' ';
if constexpr (std::is_same_v<Rect, QRect>) {
// QRect may overflow. Calculate width and height in higher precision.
const qint64 w = qint64(rect.right()) - rect.left() + 1;
const qint64 h = qint64(rect.bottom()) - rect.top() + 1;
debug << w << 'x' << h;
} else {
debug << rect.width() << 'x' << rect.height();
}
}
template <class Margins>

30
tests/auto/corelib/tools/qrect/tst_qrect.cpp
View File

@ -162,6 +162,8 @@ private slots:
void smallRects() const;
void toRect();
void span();
void debug();
};
// Used to work around some floating point precision problems.
@ -4499,5 +4501,33 @@ void tst_QRect::span()
QCOMPARE(QRect::span(QPoint( 1, 10), QPoint(9, 0)), QRect(QPoint(1, 0), QPoint( 9, 10)));
}
void tst_QRect::debug()
{
QString str;
QDebug debug(&str);
debug.nospace();
str.clear();
debug << QRect();
QCOMPARE(str, "QRect(0,0 0x0)");
str.clear();
debug << QRect(10, 20, 30, 40);
QCOMPARE(str, "QRect(10,20 30x40)");
str.clear();
debug << QRect(-10, -20, 30, 40);
QCOMPARE(str, "QRect(-10,-20 30x40)");
str.clear();
debug << QRect(-10, -20, -30, -40);
QCOMPARE(str, "QRect(-10,-20 -30x-40)");
str.clear();
debug << QRect(QPoint(INT_MIN, INT_MIN), QPoint(INT_MAX, INT_MAX));
QCOMPARE(str, "QRect(-2147483648,-2147483648 4294967296x4294967296)");
}
QTEST_MAIN(tst_QRect)
#include "tst_qrect.moc"