Abstract class with fields implementing ValueObject

[John Rose]

That could be one of very many edge conditions in the JVMS that are not diagnosed directly by a validation, but that will eventually cause an error when the broken classfile is further used.

I don’t think there needs to be a special rule for this.  We don’t try to comprehensively diagnose all “impossible-to-use” classfiles.

On 9 Feb 2022, at 13:50, Frederic Parain wrote:

> There's a weird case that seems to be allowed by the Value Objects JVMS draft:
>
> An abstract class can declare non-static fields, which means it won't
> have the ACC_PERMITS_VALUE flag set, but also declare that it implements
> the ValueObject interface.
>
> The combination looks just wrong, because no class can subclass such class:
>   - identity classes are not allowed because of the presence  of
>     the ValueObject interface
>   - value classes are not allowed because of the absence of
>     ACC_PERMITS_VALUE
>
> I've looked for a rule that would prohibit such combination in the
> JVMS draft but couldn't find one.
>
> Did I miss something?
>
> Fred