The existing QIODevice::readLineInto takes a QByteArray *, so it's dependent on a QByteArray and therefore needs at least one (initial) allocation. Add QIODevice::readLineInto() that takes a QSpan, allowing the user to provide a buffer to write into and returns a QByteArrayView. QBAV and QSpan are not null terminated. Make null termination optional when reading using QIODevicePrivate::readLine(). Extend the function to accept a ReadLineOption enum parameter with a default value of "NullTerminated" to preserve old calls. Do the same to QRingBufferRef::readLine(). Add QRingBuffer::readLineWithoutTerminatingNull(). [ChangeLog][QtCore][QIODevice] Added overloads of QIODevice::readLineInto() taking QSpan and returnig a QByteArrayView. Task-number: QTBUG-126574 Change-Id: I278a42cef4c9aa64ed884027f79105b5b7d44813 Reviewed-by: Marc Mutz <marc.mutz@qt.io> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>