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Prevent an overflow warning in assertions.

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Functions like QByteArray::at() assert the given index:
    Q_ASSERT(i >= 0 && i < size();
These functions typically get inlined. Now if the index is
e.g. size() - 2, then gcc will emit an ugly warning in
client code ("assuming signed overflow does not occur when assuming
that (X - c) > X is always false").
This can be easily prevented by casting both sides of the second
comparison in the assertion to their unsigned type. The explicit
comparison to zero is then no longer necessary, since that condition
is tested implicitly by the other comparison due to unsigned arithmetic.

Change-Id: Ic7244e1fa5da00a47d1fe0ed56fb81c23d444dfe
Reviewed-by: hjk <qthjk@ovi.com>
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Christian Kandeler 2012-09-26 12:32:52 +02:00 committed by The Qt Project
parent 4c33efc322
commit 8e90e0805f
3 changed files with 7 additions and 7 deletions
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8
src/corelib/tools/qbitarray.h
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@ -120,22 +120,22 @@ Q_CORE_EXPORT QBitArray operator|(const QBitArray &, const QBitArray &);
Q_CORE_EXPORT QBitArray operator^(const QBitArray &, const QBitArray &);
inline bool QBitArray::testBit(int i) const
{ Q_ASSERT(i >= 0 && i < size());
{ Q_ASSERT(uint(i) < uint(size()));
return (*(reinterpret_cast<const uchar*>(d.constData())+1+(i>>3)) & (1 << (i & 7))) != 0; }
inline void QBitArray::setBit(int i)
{ Q_ASSERT(i >= 0 && i < size());
{ Q_ASSERT(uint(i) < uint(size()));
*(reinterpret_cast<uchar*>(d.data())+1+(i>>3)) |= uchar(1 << (i & 7)); }
inline void QBitArray::clearBit(int i)
{ Q_ASSERT(i >= 0 && i < size());
{ Q_ASSERT(uint(i) < uint(size()));
*(reinterpret_cast<uchar*>(d.data())+1+(i>>3)) &= ~uchar(1 << (i & 7)); }
inline void QBitArray::setBit(int i, bool val)
{ if (val) setBit(i); else clearBit(i); }
inline bool QBitArray::toggleBit(int i)
{ Q_ASSERT(i >= 0 && i < size());
{ Q_ASSERT(uint(i) < uint(size()));
uchar b = uchar(1<<(i&7)); uchar* p = reinterpret_cast<uchar*>(d.data())+1+(i>>3);
uchar c = uchar(*p&b); *p^=b; return c!=0; }

4
src/corelib/tools/qbytearray.h
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@ -400,9 +400,9 @@ inline int QByteArray::size() const
{ return d->size; }
inline char QByteArray::at(int i) const
{ Q_ASSERT(i >= 0 && i < size()); return d->data()[i]; }
{ Q_ASSERT(uint(i) < uint(size())); return d->data()[i]; }
inline char QByteArray::operator[](int i) const
{ Q_ASSERT(i >= 0 && i < size()); return d->data()[i]; }
{ Q_ASSERT(uint(i) < uint(size())); return d->data()[i]; }
inline char QByteArray::operator[](uint i) const
{ Q_ASSERT(i < uint(size())); return d->data()[i]; }

2
src/corelib/tools/qstring.h
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@ -1245,7 +1245,7 @@ public:
QStringRef appendTo(QString *string) const;
inline const QChar at(int i) const
{ Q_ASSERT(i >= 0 && i < size()); return m_string->at(i + m_position); }
{ Q_ASSERT(uint(i) < uint(size())); return m_string->at(i + m_position); }
#ifndef QT_NO_CAST_FROM_ASCII
// ASCII compatibility