CMP0149ΒΆ
New in version 3.27.
Visual Studio Generators select latest Windows SDK by default.
Visual Studio Generators select a Windows SDK version to put in the
WindowsTargetPlatformVersion setting in .vcxproj files.
CMake sets the CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION
variable to the selected SDK version.
Prior to CMake 3.27, the SDK version was always selected by the value of
the CMAKE_SYSTEM_VERSION variable. Users or toolchain files
could set that variable to one of the exact Windows SDK versions available
on the host system. Since CMAKE_SYSTEM_VERSION defaults to
CMAKE_HOST_SYSTEM_VERSION, and it is not guaranteed that a
matching Windows SDK version is available, CMake had to fall back to
using the latest Windows SDK version if no exact match was available.
This approach was problematic:
The latest Windows SDK might or might not be selected based on whether the host version of Windows happens to match an available SDK version.
An old Windows SDK version might be selected that has not been updated for newer language standards such as C11.
CMake 3.27 and higher prefer to ignore the exact value of
CMAKE_SYSTEM_VERSION and by default select the latest SDK
version available. An exact SDK version may be specified explicitly
using a version= field in the CMAKE_GENERATOR_PLATFORM
variable. See Visual Studio Platform Selection.
This policy provides compatibility for projects, toolchain files, and
build scripts that have not been ported away from using
CMAKE_SYSTEM_VERSION to specify an exact SDK version.
Note
This policy must be set before the first project() or
enable_language() command invocation at the top of the
project. That is when Visual Studio Generators select a
Windows SDK.
The OLD behavior for this policy is to use the exact value of
CMAKE_SYSTEM_VERSION if possible. The NEW behavior
for this policy is to ignore it.
This policy was introduced in CMake version 3.27. Use the
cmake_policy() command to set it to OLD or NEW explicitly.
Unlike many policies, CMake version 3.27.9 does not warn
when this policy is not set and simply uses OLD behavior.
Note
The OLD behavior of a policy is
deprecated by definition
and may be removed in a future version of CMake.