The minimum sdk / xcode version is a requirement, so if the minimum is not met, we should generally error out. Changing the behavior in the already released 6.6.x series is not nice though. Refactor the code to support both a warning-first and error-first approach. Keep the warning-first behavior as-is in this change and pick it to all relevant branches. A follow up change will switch the default to the error-first approach for as-of-yet unreleased Qt branches. To support both approaches, there are now two variables to flip the warnings into errors and vice-versa depending on which is the default for a particular branch: - QT_FORCE_FATAL_APPLE_SDK_AND_XCODE_CHECK - QT_FORCE_WARN_APPLE_SDK_AND_XCODE_CHECK The maximum SDK version check remains a warning, because building against the newer SDK might still work, even if it isn't yet marked as supported. Amends a29bff3d80219f54d0837b0e6e0577192011dea1 Pick-to: 6.6 Task-number: QTBUG-119490 Change-Id: I92dedd69efc266dfc1c8cf15c93887be74fc99d8 Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>