It seems like the intention has been that QT_NO_DEBUG gets set only when debug level is 'no', or 'some', as it's not set unconditionally but separately for both of these cases. The latter case is not only for 'some', however, but gets set for any debug level above that as well.
I wouldn't necessarily enable Qt debug support for 'yes' level either, but for more special debug facilities requesting 'checks' it would make sense.
It seems like the intention has been that QT_NO_DEBUG gets set only when debug level is 'no', or 'some', as it's not set unconditionally but separately for both of these cases. The latter case is not only for 'some', however, but gets set for any debug level above that as well.
I wouldn't necessarily enable Qt debug support for 'yes' level either, but for more special debug facilities requesting 'checks' it would make sense.