New in version 3.24.
Watcom runtime library flags are selected by an abstraction.
Compilers targeting the Watcom ABI have flags to select the Watcom runtime library.
In CMake 3.23 and below, Watcom runtime library selection flags are added to
CMAKE_<LANG>_FLAGS_<CONFIG> cache entries by CMake
automatically. This allows users to edit their cache entries to adjust the
flags. However, the presence of such default flags is problematic for
projects that want to choose a different runtime library programmatically.
In particular, it requires string editing of the
CMAKE_<LANG>_FLAGS_<CONFIG> variables with knowledge of the
CMake builtin defaults so they can be replaced.
CMake 3.24 and above prefer to leave the Watcom runtime library selection flags
out of the default
CMAKE_<LANG>_FLAGS_<CONFIG> values and instead
offer a first-class abstraction. The
WATCOM_RUNTIME_LIBRARY target property may be set to
select the Watcom runtime library. If they are not set then CMake uses the
MultiThreadedDLL on Windows and
SingleThreaded on other
platforms, which is equivalent to the original flags.
This policy provides compatibility with projects that have not been updated
to be aware of the abstraction. The policy setting takes effect as of the
enable_language() command that enables
a language whose compiler targets the Watcom ABI.
Once the policy has taken effect at the top of a project, that choice must be used throughout the tree. In projects that have nested projects in subdirectories, be sure to convert everything together.
OLD behavior for this policy is to place Watcom runtime library
flags in the default
entries and ignore the
NEW behavior for this policy is to not place Watcom runtime
library flags in the default cache entries and use the abstraction instead.
This policy was introduced in CMake version 3.24. Use the
cmake_policy() command to set it to
Unlike many policies, CMake version 3.28.20231205-g72ce0e6 does not warn
when this 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.