CMP0117ΒΆ
New in version 3.20.
MSVC RTTI flag /GR is not added to
CMAKE_CXX_FLAGS by default.
When using MSVC-like compilers in CMake 3.19 and below, the RTTI flag
/GR is added to CMAKE_CXX_FLAGS by
default. This behavior is left from support for MSVC versions from Visual
Studio 2003 and below that did not enable RTTI by default. It is no longer
necessary. Furthermore, it is problematic for projects that want to change
to /GR- programmatically. In particular, it requires string editing of
the CMAKE_CXX_FLAGS variable with knowledge
of the CMake builtin default so it can be replaced.
CMake 3.20 and above prefer to leave out /GR from the value of
CMAKE_CXX_FLAGS by default.
This policy provides compatibility with projects that have not been updated
to expect the lack of the /GR flag. The policy setting takes effect as
of the first project() or enable_language() command that
initializes CMAKE_CXX_FLAGS.
Note
Once the policy has taken effect at the top of a project for a given language, that choice must be used throughout the tree for that language. In projects that have nested projects in subdirectories, be sure to convert everything together.
The OLD behavior for this policy is to place the MSVC /GR flag in the
default CMAKE_CXX_FLAGS cache entry. The
NEW behavior for this policy is to not place the MSVC /GR flag in
the default cache entry.
This policy was introduced in CMake version 3.20.
It may be set by cmake_policy() or cmake_minimum_required().
If it is not set, CMake does not warn, and uses OLD behavior.
Note
The OLD behavior of a policy is
deprecated by definition
and may be removed in a future version of CMake.