The qt_set01 function had a critical argument quoting flaw. This happened because CMake removes quotes when calling the function, causing variable substitution in the condition evaluation. For example, calling qt_set01(QNX CMAKE_SYSTEM_NAME STREQUAL "QNX") with QNX already set to 1 would evaluate CMAKE_SYSTEM_NAME STREQUAL QNX (where QNX expands to 1) instead of CMAKE_SYSTEM_NAME STREQUAL "QNX". This particularly affected users with QNX toolchains that pre-set the QNX variable, causing configure to fail. Replace all qt_set01 calls with explicit if/else blocks that properly preserve string literals and avoid the eval-like behavior. Remove the qt_set01 function. The platform detection code is now admittedly more verbose but plain CMake without argument quoting pitfalls. Pick-to: 6.8 6.10 Fixes: QTBUG-142267 Change-Id: I642fc8582001b8c7b7b6ff56eae7ccabc89ba565 Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>