Introduce a bunch of helper functions to manipulate compiler
flags and linker flags for the
CMAKE_<LANG>_FLAGS_<CONFIG>
and
CMAKE_<LINK_TYPE>_LINKER_FLAGS_<CONFIG>
CMake variables.
These variables can be assigned and modified either in the cache
or for a specific subdirectory scope, which will apply the flags
only to targets in that scope.
Add qt_internal_add_optimize_full_flags() function which mimics
qmake's CONFIG += optimize_full behavior.
Calling it will force usage of the '-O3' optimization flag on supported
platforms (falling back '-O2' where not supported).
Use the function for the Core and Gui subdirectories, to enable full
optimization for the respective Qt modules as it is done in the qmake
projects.
To ensure that the global qmake-like compiler flags are assigned
eveywhere,
qt_internal_set_up_config_optimizations_like_in_qmake() needs
to be called after Qt global features like optimize_size and
optimize_full are available.
This means that qtbase and its standalone tests need some special
handling in regards to when to call that function.
Task-number: QTBUG-86866
Change-Id: Ic7ac23de0265561cb06a0ba55089b6c0d3347441
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
07b6d3367d