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 3.15.7 warns when the policy is not set and uses OLD behavior. Use the cmake_policy() command to set it to OLD or NEW explicitly.