Work around a binary incompatibility in MSVC

The fix in b8fe5e1bbc7f341d03d2704a6110d6e3240589bb (for bug
QTBUG-27277) created two sets of begin() and end() functions for
QVector. That was required because QTypedArrayData::iterator and
QTypedArrayData::const_iterator have non-implicit copy constructors,
which means the variants returning a strict iterator need to pass the
storage pointer as an implicit first parameter. With the fix, the
compiler would emit functions with two different names for each
variant, which couldn't be merged.

If we remove those copy constructors, the compiler might be able to
generate the same code (no implicit first parameter) for both
functions.

Now, enter MSVC. Due to QPolygon, QVector<QPoint> and QVector<QPointF>
are "extern templates". That is, the compiler is not allowed to inline
anything, it must generate calls into QtCore (which we must fix for Qt
6, if we can). That means QtCore would only have one set of begin() /
end() functions. If an application tried to use the other set by
defining QT_STRICT_ITERATORS, you'd get a linker error for:

  ?begin@?$QVector@VQPoint@@@@QEAA?AViterator@?$QTypedArrayData@VQPoint@@@@V23@@Z
  (class QTypedArrayData<class QPoint>::iterator QGenericArray<class QPoint>::begin(class QTypedArrayData<class QPoint>::iterator))

Change-Id: I5c10a7d0a4855f4ba84056d313c6a800ecdcfe37
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Olivier Goffart <ogoffart@woboq.com>

0 files changed, 0 insertions, 0 deletions