# CMP0063

Honor visibility properties for all target types.

The `<LANG>_VISIBILITY_PRESET` and `VISIBILITY_INLINES_HIDDEN` target properties affect visibility of symbols during dynamic linking. When first introduced these properties affected compilation of sources only in shared libraries, module libraries, and executables with the `ENABLE_EXPORTS` property set. This was sufficient for the basic use cases of shared libraries and executables with plugins. However, some sources may be compiled as part of static libraries or object libraries and then linked into a shared library later. CMake 3.3 and above prefer to honor these properties for sources compiled in all target types. This policy preserves compatibility for projects expecting the properties to work only for some target types.

The `OLD` behavior for this policy is to ignore the visibility properties for static libraries, object libraries, and executables without exports. The `NEW` behavior for this policy is to honor the visibility properties for all target types.

This policy was introduced in CMake version 3.3. CMake version 3.18.3 warns when the policy is not set and uses `OLD` behavior. Use the `cmake_policy()` command to set it to `OLD` or `NEW` explicitly.

Note

The `OLD` behavior of a policy is `deprecated by definition` and may be removed in a future version of CMake.