New in version 3.21.

The find_file(), find_path(), find_library() and find_program() commands cache their result in the variable specified by their first argument. Prior to CMake 3.21, if a cache variable of that name already existed before the call but the cache variable had no type, any non-cache variable of the same name would be discarded and the cache variable was always used (see also CMP0126 for a different but similar behavior). This contradicts the convention that a non-cache variable should take precedence over a cache variable of the same name. Such a situation can arise if a user sets a cache variable on the command line without specifying a type, such as cmake -DMYVAR=blah ... instead of cmake -DMYVAR:FILEPATH=blah.

Related to the above, if a cache variable of the specified name already exists and it does have a type, the various find_...() commands would return that value unchanged. In particular, if it contained a relative path, it would not be converted to an absolute path in this situation.

When policy CMP0125 is set to OLD or is unset, the behavior is as described above. When it is set to NEW, the behavior is as follows:

  • If a non-cache variable of the specified name exists when the find_...() command is called, its value will be used regardless of whether a cache variable of the same name already exists or not. A cache variable will not be created in this case if no such cache variable existed before. If a cache variable of the specified name did already exist, the cache will be updated to match the non-cache variable.

  • The various find...() commands will always provide an absolute path in the result variable, except where a relative path provided by a cache or non-cache variable cannot be resolved to an existing path.

This policy was introduced in CMake version 3.21. Use the cmake_policy() command to set it to OLD or NEW explicitly. Unlike many policies, CMake version 3.28.6 does not warn when the policy is not set and simply uses OLD behavior.


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