Help: Mention if(POLICY) and NO_POLICY_SCOPE in policies manual.

This commit is contained in:
Stephen Kelly 2013-12-20 12:19:11 +01:00
parent a0ce1e36b6
commit 8f849b9071
1 changed files with 15 additions and 1 deletions

View File

@ -21,7 +21,21 @@ for a policy, also avoiding the warning.
The :command:`cmake_minimum_required` command does more than report an
error if a too-old version of CMake is used to build a project. It
also sets all policies introduced in that CMake version or earlier to
NEW behavior.
NEW behavior. To manage policies without increasing the minimum required
CMake version, the :command:`if(POLICY)` command may be used::
if(POLICY CMP0990)
cmake_policy(SET CMP0990 NEW)
endif()
This has the effect of using the NEW behavior with newer CMake releases which
users may be using and not issuing a compatibility warning.
The setting of a policy is confined in some cases to not propagate to the
parent scope. For example, if the files read by the :command:`include` command
or the :command:`find_package` command contain a use of :command:`cmake_policy`,
that policy setting will not affect the caller by default. Both commands accept
an optional ``NO_POLICY_SCOPE`` keyword to control this behavior.
The :variable:`CMAKE_MINIMUM_REQUIRED_VERSION` variable may also be used
to determine whether to report an error on use of deprecated macros or