RFR: JDK-8216558: Lookup.unreflectSetter(Field) fails to throw IllegalAccessException for final fields

Mandy Chung mandy.chung at oracle.com
Fri Jan 11 22:47:29 UTC 2019

On 1/11/19 2:38 PM, David Holmes wrote:
> There seem to be a number of spec issues around this. Shouldn't 
> findStaticSetter say something about what happens when the field is 
> final? Same for findSetter? This issue seems to be much bigger than 
> just a simple bug fix.

I don't see any issue with the spec for findSetter and 
findStaticSetter.  findSetter returns a method handle equivalent to 
`putField` bytecode and it throws IAE when access checking is performed 
since it's final and not writeable.  Similiarly for findStaticSetter.

> A CSR request will need to be filed.

Of course, as this is a spec change.


> David
> -----
> On 12/01/2019 5:07 am, Mandy Chung wrote:
>> This issue requires a spec change and it's a behavioral change. 
>> Field::set on a static final field throws IAE.  Although there are 
>> few cases in the world that hack around it, I think the compatibility 
>> risk is low in this change.
>> I added a suggested fix in the JBS issue.
>> Mandy
>> On 1/11/19 10:07 AM, Mandy Chung wrote:
>>> Hi Adam,
>>> This is indeed a bug.    I suggest to do the check in the 
>>> checkAccess method closes to where it performs the instance final 
>>> field check. Please also add a test case.
>>> Mandy
>>> On 1/11/19 6:38 AM, Adam Farley8 wrote:
>>>> Hi All,
>>>> First; thanks for responding so quickly. :)
>>>> Second, it sounds like changing the contents of a final field is
>>>> acceptable under the spec, but *not* changing the contents of a static
>>>> final field.
>>>> The test case uploaded to the bug uses a static final field for the 
>>>> test,
>>>> so I think we can agree that the ability to create a setter for a 
>>>> static
>>>> final field is still a bug.
>>>> It sounds like the same fix could work if we check for "static" 
>>>> when we
>>>> check for "final", with a modified message.
>>>> As Field.set (post-setAccessible) fails to set the value of a 
>>>> static final
>>>> field, I think we can agree that unreflectSetter should fail to 
>>>> create a
>>>> setter MethodHandle for this same field.
>>>> Best Regards
>>>> Adam Farley
>>>> IBM Runtimes

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