JDK 8 code review request for 7140820 Add covariant overrides to Collections clone methods

[Joe Darcy]

On 01/29/2012 10:52 PM, Rémi Forax wrote:
> On 01/30/2012 04:58 AM, Joe Darcy wrote:
>> Hello,
>>
>> As an indirect outgrowth of warnings cleanup day, various categories 
>> of warnings can be eliminated by in the use of Cloneable types by 
>> overriding the
>>
>>     Object clone()
>>
>> method inherited from java.lang.Object with a covariant override such as
>>
>>     MyType clone()
>>
>> Please review my changes for
>>
>>     7140820 Add covariant overrides to Collections clone methods
>>     http://cr.openjdk.java.net/~darcy/7140820.0/
>>
>> which add such covariant override clone methods to collections and a 
>> few other classes in java.util.  Doing a full JDK build with these 
>> changes, I've also made alterations to other classes to remove now 
>> superfuous casts (casts which are a javac lint warning!) and some 
>> unneeded @SuppressWarnings annotations.  I also cleaned up a few 
>> rawtypes warnings while in editing files in java.util.
>>
>> (Note that the old specListeners method in EventRequestSpecList.java 
>> was much buggy; it cast an ArrayList from runtime.specListeners to a 
>> Vector.)
>>
>> Thanks,
>>
>> -Joe
>
> WTF !
>
> while it's maybe a binary compatible change, I haven't take a look to 
> all modified classes to be sure
> it's not a source compatible change.

Adding the covariant override is a binary compatible change because 
there would be a bridge method providing the original "Object clone()" 
signature.

>
> People had created class that inherits from ArrayList and override clone,
> while it's not a good practice, there is a *lot* of code from pre-1.5 
> days that does exactly that,
> this change will simply break all those codes.
>

*sigh*

Yes, I didn't fully consider the source compatibility implications given 
that these types can be subclasses; I'll look this over some more.

(This was meant to be part of a larger effort to review of potentially 
overridable clone methods in the JDK.  I wrote an annotation processor 
to look over the code base to find potential classes to upgrade; I can 
refine the processor to look for classes that don't override clone and 
are also final or effectively final, having no accessible constructors.)

Thanks Remi,

-Joe