Emit warning when feeding something genex when it doesn't consume it
I was attempting for quite some time to use genex for having build config specific IPO settings, for example like this:
set_property(TARGET hello_world PROPERTY INTERPROCEDURAL_OPTIMIZATION $<CONFIG:Release>)
Later I learned that some properties do not consume genex. It would be useful if the properties that do not consume genex emit warnings when they're being fed genex.