Previously if Qt was configured with -developer-build, configure would pass to CMake -DINPUT_developer_build=ON, which will ensure that both FEATURE_developer_build and QT_FEATURE_developer_build are set to ON. Then if somebody tries to toggle FEATURE_developer_build to OFF in the CMakeCache.txt and rerun cmake, the feature will bounce back to ON, due to the code in QtSetup.cmake that doesn't take into account if FEATURE_developer_build is already defined, and thus reset it based on the value that is cached in INPUT_developer_build. Change the checks for INPUT_developer_build and INPUT_no_prefix, to take into account the defined-ness of their FEATURE_ counterparts. If they are defined, ignore the INPUT_ values. This allows toggling the FEATURE_ variables and also aligns with the INPUT_ handling behavior that we have in qt_evaluate_feature which ignores INPUT_ values once the FEATURE_ is defined. While this aligns the behavior with other features, there is still a problem. If you first configure without -developer-build, and FEATURE_developer_build is set OFF, and then reconfigure with -developer-build, because FEATURE_developer_build is already defined, the INPUT_developer_build=ON is ignored. This is a problem for other features as well and will be handled in a follow up change. Pick-to: 6.6 Task-number: QTBUG-112957 Change-Id: I4f31157b0e7963e4d43e28062a585e939ceea0c1 Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>