The XmlStringRef(const QString*) ctor calls the (const QString *, int, int) ctor, passing QString::length() as the third argument. If the input QString had more than 2 Gi characters, the resulting XmlStringRef represents only the prefix of the input (mod (INT_MAX+1)). Fix by making the delegatee ctor use qsizetype instead of int, allowing to pass data through without truncation. [ChangeLog][QtCore][QXmlStreamReader] Fixed several bugs regarding handling of documents larger than 2Gi characters on 64-bit platforms. Pick-to: 6.3 6.2 Fixes: QTBUG-102466 Change-Id: Ie48274190ac359f62d3ec3d8fe60eb43cc2c362a Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>