RFR [lworld] 8239929: Object.newIdentity() replacement for new Object()

[Roger Riggs]

Hi Mandy,

I don't think we are ready for the storm of compiler warnings.
There are 100 in java.base alone.  We can change that later when we are 
ready to phase it in.

Roger


On 2/27/20 5:40 PM, Mandy Chung wrote:
> I think we should add @Deprecated in the Object constructor.
>
> Otherwise, looks fine.
>
> Mandy
>
> On 2/25/20 11:20 AM, Roger Riggs wrote:
>> Please review the static factory of an IdentityObject to replace "new 
>> Object()"
>> as mentioned in [1].
>>
>> No replacements proposed yet.  There are 504 instances of "new 
>> Object()" in JDK modules.
>> @@ -38,15 +38,36 @@
>>
>>   */
>>  public class Object {
>>
>>      /**
>>       * Constructs a new object.
>> +     * @apiNote {@link Object#newIdentity} should be used instead of 
>> {@code new Object()}.
>>       */
>>      @HotSpotIntrinsicCandidate
>>      public Object() {}
>>
>>      /**
>> +     * Constructs a new Object implementing the IdentityObject 
>> interface.
>> +     * The object is a unique IdentityObject suitable for all purposes
>> +     * that previously for which {@code new Object{}} was used 
>> including synchronization,
>> +     * mutexes and unique placeholders.
>> +     *
>> +     * @return a new Object implementing the IdentityObject interface
>> +     * @since Valhalla
>> +     */
>> +    public static IdentityObject newIdentity() {
>> +        return new IdentityInstance();
>> +    }
>> +
>> +    /**
>> +     * IdentityInstance replaces plain {@code new Object()}.
>> +     */
>> +    private final static class IdentityInstance implements 
>> IdentityObject {
>> +        private IdentityInstance() {}
>> +    }
>> +
>>
>>
>> As a Webrev:
>> http://cr.openjdk.java.net/~rriggs/webrev-object-newinstance-8239929/
>>
>> Thanks, Roger
>>
>> [1] 
>> http://cr.openjdk.java.net/~briangoetz/valhalla/sov/02-object-model.html
>