This code:

interface Iface<T1> {}

class Impl implements Iface<Impl> {}

class Acceptor<T2 extends Iface<T2>> {
    public Acceptor(T2 obj) {}
}

public class Test {
    public static void main(String[] args) {
        Acceptor<?> acceptor = new Acceptor<>(new Impl());
    }
}

which is accepted by javac 7 is rejected by javac 8 with this error message:

Test.java:11: error: incompatible types: cannot infer type arguments for Acceptor<>
        Acceptor<?> acceptor = new Acceptor<>(new Impl());
                                           ^
    reason: inference variable T2 has incompatible bounds
      equality constraints: Impl
      upper bounds: Iface<CAP#1>,Iface<T2>
  where T2 is a type-variable:
    T2 extends Iface<T2> declared in class Acceptor
  where CAP#1 is a fresh type-variable:
    CAP#1 extends Iface<CAP#1> from capture of ?
1 error