fredemmott-pro:hhtest fredemmott$ hhvm --version
HipHop VM 3.23.2-0brew (rel)
Compiler: 1511205649_N
Repo schema: ec6e576aec2517122b203aece1c3a968530d66be
fredemmott-pro:hhtest fredemmott$ hhvm test.php
object(Foo)#1 (0) {
}
object(Foo)#1 (0) {
}
fredemmott-pro:hhtest fredemmott$ cat test.php
<?hh

<<__ConsistentConstruct>>
class Foo {
    <<__Memoize>>
    final public static function get(): this {
        return new static();
    }
}

class Bar extends Foo {}
class Baz extends Foo {}

var_dump(Bar::get(), Baz::get());