There is no need for this variable to be stored in CMake's cache. We don't perform expensive operations to set up QT_SYNCQT, and we even unset the cache variable to ensure it gets recomputed on reconfiguration. We still store QT_SYNCQT in a global property, because the function qt_ensure_sync_qt is called in different directory scopes, and we want to avoid re-calculations for every subdir. It's now possible for the user to set QT_SYNCQT (see QTBUG-88088 for motivation). Also, in a non-prefix build, changes to syncqt.pl in the source dir are reflected upon re-configuration in the build tree (because qt_copy_or_install is called on every configure). Pick-to: 6.2 Fixes: QTBUG-88088 Task-number: QTBUG-75290 Change-Id: I6137b060d200d3dafd4a64d5a6c1bd2549723d78 Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>