Mark the generated source file with the GENERATED property explicitly
since it is not marked automatically as the output of any custom
command. Mark both the 0 and 1 variants so it works no matter the
outcome of the generator expression.
Allow setting build properties based on the features available
for a target. The availability of features is determined at
generate-time by evaluating the link implementation.
Ensure that the <LANG>_STANDARD determined while evaluating
COMPILE_FEATURES in the link implementation is not lower than that
provided by the INTERFACE of the link implementation. This is
similar to handling of transitive properties such as
POSITION_INDEPENDENT_CODE.
Brad King
Stephen Kelly