New in version 3.8.
Visual Studio preferred tool architecture.
The Visual Studio Generators for VS 2013 and above support using either the 32-bit or 64-bit host toolchains by specifying a host=x86 or host=x64 value in the CMAKE_GENERATOR_TOOLSET option. CMake provides the selected toolchain architecture preference in this variable (x86, x64, or empty).
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Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.19/variable/CMAKE_VS_PLATFORM_TOOLSET_HOST_ARCHITECTURE.html