# CMP0074

`find_package()` uses `<PackageName>_ROOT` variables.

In CMake 3.12 and above the `find_package(<PackageName>)` command now searches prefixes specified by the `<PackageName>_ROOT` CMake variable and the `<PackageName>_ROOT` environment variable. Package roots are maintained as a stack so nested calls to all `find_*` commands inside find modules also search the roots as prefixes. This policy provides compatibility with projects that have not been updated to avoid using `<PackageName>_ROOT` variables for other purposes.

The `OLD` behavior for this policy is to ignore `<PackageName>_ROOT` variables. The `NEW` behavior for this policy is to use `<PackageName>_ROOT` variables.

This policy was introduced in CMake version 3.12. CMake version 3.15.0-rc3 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.