We're moving to Visual Studio 2017 and VS2017 prompts us to retarget the projects for 2 things: Windows SDK Version and Platform Toolset.
Currently our application can run on older Windows versions (at least to Server 2003, possibly older), and we need to retain the same (I know they're not supported anymore, but that's the customer's requirement).
Assuming that our code (which is all C++ in case it makes a difference) does not use any APIs which are only available on newer versions of Windows, will re-targeting to a newer version of the Windows SDK restrict or limit the versions of Windows that our app will run on?
And while on the subject, will re-targeting to a newer version of the Windows SDK have any pros or cons (ex. performance) (again, assuming we don't use any of the new APIs that are only available on newer Windows)?
No, using a newer SDK allows use of newer funcntionality but it does not require doing so. So long as you are careful to only use functionality that is present on the version of windows you are interested in your program will continue to work. You will, however, likely need to install the vs2017 runtime on the client systems.
You will need the VC++ runtime for the development kit that you are building from. Statically linking this library will remove this requirement, as the runtime is embedded in your binary.
来源：https://stackoverflow.com/questions/48215453/does-windows-sdk-restrict-eligible-versions-of-windows