On macOS, compiling Qt for debug only (non-framework), the generated CMake files are generated incorrectly.
./configure -debug -no-framework
For example: lib/cmake/Qt5Core/Qt5CoreConfig.cmake contains a reference to libQt5Core*_debug*_debug.5.12.3.dylib instead of libQt5Core_debug.5.12.3.dylib. (The _debug suffix is added twice)
I believe, this is because at the end of qt_module.prf the TARGET variable is set to the result of the call chain qt5LibraryTarget -> qtLibraryTarget -> qtPlatformTargetSuffix (All in qt_functions.prf.
Then, further on in create_cmake.prf (~lines 200-220), TARGET is copied into CMAKE_QT_STEM and is then assumed to be a suffixless name of the target binary in a multi-configuration build.
However, as seen in qtPlatformTargetSuffix, in the case of a macOS single configuration debug build, CMAKE_QT_STEM will already have the _debug suffix added.