Since commit 83ddc4d289 (VS: Do not select a Windows SDK too high for
current VS version, 2017-08-07, v3.13.0-rc1~72^2~2) we enforce a maximum
SDK version for the VS 2015 generator. The blog post linked in the
original commit is no longer available, but it can be seen here:
* https://web.archive.org/web/20190108032520/https://blogs.msdn.microsoft.com/chuckw/2018/10/02/windows-10-october-2018-update/
In particular, it states:
> VS 2015 Users: The Windows 10 SDK (15063, 16299, 17134, 17763)
> is officially only supported for VS 2017.
However, in some circumstances a higher version can be used.
Add a `CMAKE_VS_WINDOWS_TARGET_PLATFORM_VERSION_MAXIMUM` to override the
generator's default maximum SDK version.
Fixes: #20633
Define a `CMAKE_WINDOWS_KITS_10_DIR` environment variable to allow
users to tell CMake about a custom Windows 10 SDK directory. We
choose to make this an environment variable rather than a CMake
variable or cache entry because:
* Using a custom directory also requires custom external MSBuild
configuration. Therefore users are already configuring a
custom environment.
* The custom directory must be set consistently in all parts of
a build including nested projects. An environment variable
avoids requiring users to thread the setting into nested builds.
Fixes: #16743
Since commit v3.4.0-rc1~5^2~1 (VS: Add support for selecting the Windows
10 SDK, 2015-09-30) the VS 2015 generator requires a Windows 10 SDK to
be available when CMAKE_SYSTEM_VERSION specifies Windows 10 (e.g. when
building on a Windows 10 host). Howewver, it is possible to install VS
2015 without any Windows 10 SDK. Instead of failing with an error
message about the lack of a Windows 10 SDK, simply tolerate this case
and use the default Windows 8.1 SDK. Since building for Windows Store
still requires the SDK, retain the diagnostic in that case.
Teach the VS 2015 generator to produce a WindowsTargetPlatformVersion
value. Use the CMAKE_SYSTEM_VERSION to specify the version and if not
set choose a default based on available SDKs. Activate this behavior
when targeting Windows 10.
Co-Author: Brad King <brad.king@kitware.com>
jonathan molinatto