# CMP0075

Include file check macros honor `CMAKE_REQUIRED_LIBRARIES`.

In CMake 3.12 and above, the

- `check_include_file` macro in the `CheckIncludeFile` module, the
- `check_include_file_cxx` macro in the `CheckIncludeFileCXX` module, and the
- `check_include_files` macro in the `CheckIncludeFiles` module

now prefer to link the check executable to the libraries listed in the `CMAKE_REQUIRED_LIBRARIES` variable. This policy provides compatibility with projects that have not been updated to expect this behavior.

The `OLD` behavior for this policy is to ignore `CMAKE_REQUIRED_LIBRARIES` in the include file check macros. The `NEW` behavior of this policy is to honor `CMAKE_REQUIRED_LIBRARIES` in the include file check macros.

This policy was introduced in CMake version 3.12. CMake version 3.15.0-rc4 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.