cmake/Help/command/UNSET_NOTE.txt

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2023-07-02 19:51:09 +02:00
.. note::
When evaluating :ref:`Variable References` of the form ``${VAR}``, CMake
first searches for a normal variable with that name. If no such normal
variable exists, CMake will then search for a cache entry with that name.
Because of this, **unsetting a normal variable can expose a cache variable
that was previously hidden**. To force a variable reference of the form
``${VAR}`` to return an empty string, use ``set(<variable> "")``, which
clears the normal variable but leaves it defined.