MSVC 2015 builds Failing After 2017 Support added

On Sat Feb 18 19:52:23 UTC 2017 Luke Benes wrote:

> I'm getting the following build error: 
> C:\Program Files
(x86)\MSBuild\Microsoft.Cpp\v4.0\V140\Platforms\Win32\PlatformToolsets\
v140\Toolset.targets(34,5): >error MSB8036: The Windows SDK version
10.0.10240.0 was not found. >Install the required version of Windows
SDK or change the SDK version >in the project property pages or by
right-clicking the solution and >selecting "Retarget solution".

Hm.., what was changed since MSVC 2017 support, is that we are passing 
toolset version, see commit message of the change you pointed to, and
particularly this line in external packages make files:

  $(if $(filter
$(UCRTVERSION),),,/p:WindowsTargetPlatformVersion=$(UCRTVERSION)) \

e.g.

https://cgit.freedesktop.org/libreoffice/core/diff/external/lcms2/Exter
nalProject_lcms2.mk?id=b862cbdd345ec57c2595629ded6a3969e1e65d56

So, if your UCRTVERSION is 10.0.10240.0 (can you verify in
config_host.mk?), then the corresponding msbuild toolset must be
installed. Looks like you have only partially installed SDK 10 on your
machine, so you are on your own.

As explained in the commit message, that was needed to force msbuild to
use non default toolset (fro SDK 10) when no default one (SDK 8) is
installed on the system.

As Tor pointed out, complete installation of what is coming with your
compiler should do the job.

> Have Windows SDK requirements changed for 2015 or is this a bug? 

Normally we announce something like that on dev ML, or even ask for ESC
decision. So, no, it wasn't intended. Also note, that all TBs have no
problems with verification of MSVC 2017 change.