CMP0102ΒΆ
The mark_as_advanced()
command no longer creates a cache entry if one
does not already exist.
In CMake 3.16 and below, if a variable was not defined at all or just defined
locally, the mark_as_advanced()
command would create a new cache
entry with an UNINITIALIZED
type and no value. When a find_path()
(or other similar find_
command) would next run, it would find this
undefined cache entry and set it up with an empty string value. This process
would end up deleting the local variable in the process (due to the way the
cache works), effectively clearing any stored find_
results that were only
available in the local scope.
The OLD
behavior for this policy is to create the empty cache definition.
The NEW
behavior of this policy is to ignore variables which do not
already exist in the cache.
This policy was introduced in CMake version 3.17. Use the
cmake_policy()
command to set it to OLD
or NEW
explicitly.
Unlike many policies, CMake version 3.17.5 does not warn
when this policy is not set and simply uses OLD
behavior.
Note
The OLD
behavior of a policy is
deprecated by definition
and may be removed in a future version of CMake.