Can @Stable (or something similar) be made accessible?
peter.levart at gmail.com
Fri Jan 12 11:35:39 UTC 2018
On 01/12/2018 09:47 AM, Andrew Haley wrote:
> On 12/01/18 04:33, Jason Greene wrote:
>> The internal @Stable facility provides the desired semantics and
>> precision, but it is heavily locked down, with privileged code
>> checks and export restrictions. Could this be made more accessible
>> (or perhaps a variant restricted to just final fields)? Informing
>> the compiler that a final field is a true lazy initialized constant,
>> with no store-to-final seems a pretty useful construct in general. I
>> can understand that the long term desire is that this shouldn’t be
>> necessary, and should be inferred , but at that point the
>> annotation is still useful as documentation and legacy
>> compatibility. If nothing else could it be allowed in non-privileged
>> code via some flag?
> I don't know of any way to do that without compromising the integrity
> of the JVM. All that anybody would have to do to break the VM is to
> define a field as @Stable and then change the field.
Would you be so kind to explain how this breakage occurs? I can
understand that improper use of @Stable annotation may break the
intended semantics of a program, but to break the integrity of VM? I'm
trying to imagine the scenario, but can't.
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