New in version 3.21.
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
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.
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.
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
Unlike many policies, CMake version 3.26.20230321-gdea7cbc does not warn when the policy
is not set and simply uses
OLD behavior of a policy is
deprecated by definition
and may be removed in a future version of CMake.