FULL PRODUCT VERSION :
java version "9-ea"
Java(TM) SE Runtime Environment (build 9-ea+142)
Java HotSpot(TM) 64-Bit Server VM (build 9-ea+142, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Darwin macbook-pro 16.1.0 Darwin Kernel Version 16.1.0: Thu Oct 13 21:26:57 PDT 2016; root:xnu-3789.21.3~60/RELEASE_X86_64 x86_64

A DESCRIPTION OF THE PROBLEM :
I have existing Java 8 source code that has static methods with generic parameters. In Java 8 it was possible to denote method references using these type parameters:

static <T extends Comparable<? super T>> Comparator<T> comparator() {
    return (Comparator<T> & Serializable) T::compareTo;
}

JDK 9 does not compile the code any more.

REGRESSION. Last worked in version 8u101

ADDITIONAL REGRESSION INFORMATION:
java version "1.8.0_101"
Java(TM) SE Runtime Environment (build 1.8.0_101-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.101-b13, mixed mode)

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Create the java class showed in 'Source code for an executable test case:' below.

2. Compile the class using 'javac test/Example.java'

3. Run the class using 'java test/Example'


EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The example should print 'true' to the console.
ACTUAL -
The java compiler of JDK 9 does abort compilation with an error. For details see Error Message(s)/Crash Logs below.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
test/Example.java:14: error: incompatible types: invalid method reference
        return (Comparator<T> & Serializable) T::compareTo;
                                              ^
    method compareTo in interface Comparable<T#2> cannot be applied to given types
      required: ? super T#1
      found: T#1,T#1
      reason: actual and formal argument lists differ in length
  where T#1,T#2 are type-variables:
    T#1 extends Comparable<? super T#1> declared in method <T#1>comparator()
    T#2 extends Object declared in interface Comparable
1 error

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package test;

import java.io.Serializable;
import java.util.Comparator;

interface Example {

    static void main(String[] args) {
        Comparator<String> comparator = comparator();
        System.out.println(comparator.compare("a", "b") == -1);
    }

    static <T extends Comparable<? super T>> Comparator<T> comparator() {
        return (Comparator<T> & Serializable) T::compareTo;
    }

}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
We can use a lambda expression instead of a method reference.

The example provided here can be expressed like this:

@SuppressWarnings("unchecked")
static <T extends Comparable<? super T>> Comparator<T> comparator() {
    return (Comparator<T> & Serializable) (o1, o2) -> ((Comparable<T>) o1).compareTo(o2);
}