Java could have done the same by implementing erasure as a VM-level construct that's only invoked when a generic class is used in a non-generic manner. That is,

Java could have done the same by implementing erasure as a VM-level construct that's only invoked when a generic class is used in a non-generic manner. That is, using List is equivalent to using List<Object>, which I think even retains semantic equivalence. Bonus points for gating the feature behind pre-5 class versions.