| CMP0102 |
| ------- |
| |
| The :command:`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 :command:`mark_as_advanced` command would create a new cache |
| entry with an ``UNINITIALIZED`` type and no value. When a :command:`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 |
| :command:`cmake_policy` command to set it to ``OLD`` or ``NEW`` explicitly. |
| Unlike many policies, CMake version |release| does *not* warn |
| when this policy is not set and simply uses ``OLD`` behavior. |
| |
| .. include:: DEPRECATED.txt |