For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.
warning C28263: A syntax error in a conditional annotation was found for Intrinsic annotation
The Code Analysis tool reports this warning when the return value for the specified function has a conditional value. This warning indicates an error in the annotations, not in the code being analyzed. If the function declaration is in a header file, the annotation should be corrected so that it matches the header file.
The result list for the function and parameter specified has multiple unconditional values.
Typically, this indicates that more than one unconditional
__drv_valueIs annotations have been used to specify a result value.