`auto-unexpected-qstringbuilder` only partially applies to Qt>=6.7
It was fixed last year https://codereview.qt-project.org/c/qt/qtbase/+/479775
However, the case of lambda returning QStringBuilder
appears to be unfixed https://bugreports.qt.io/browse/QTBUG-117699 https://bugreports.qt.io/browse/QTBUG-47066
Edited by shenleban tongying