Suppose the user connects QProcess::readyReadStandardOutput with a
slot that calls QCoreApplication::processEvents.
Assume the event loop did not handle events between QProcess::start
and QProcess::waitForFinished. The process writes to stdout and exits.
QProcessPrivate::waitForFinished calls drainOutputPipes which calls
QWindowsPipeWriter::waitForReadyRead. This in turn will trigger
_q_processDied via the readyRead signal and processEvents.
_q_processDied will delete the pid object and set pid to null.
After drainOutputPipes returns, _q_processDied is called again but it
must not be called if pid is already destroyed.
Prevent calling _q_processDied if pid is null.
Task-number: QTBUG-48697
Change-Id: Iee047938ee1529057a1a43d71f4e882750903c7e
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
6f75c189e1