[records] Specify use of @Override and @SafeVarargs on record components

[Tagir Valeev]

I agree it is silly to put these annos on record components. On the other
> hand, I am not sure the spec should prohibit them -- seems more the sort of
> thing an IDE should say "hey, that was probably dumb, are you sure you want
> that?"
>
> In any case, it is reasonable for a compiler to error in the case of
> @Override on a component whose accessor does not override something --
> because we should type-check implicit members as well as explicit.
>

The same argument applies to @SafeVarargs. The compiler will implicitly
apply it to the accessor method but according to the spec, this annotation
cannot be applied to non-vararg method, and accessor method is never
vararg, hence this should be an error. I feel this should be covered by
spec because @SafeVarargs is fully specified in any other aspect. E. g.
it's equally silly to put it on the method without arguments and it's a
compilation error, not just IDE warning.

With best regards,
Tagir Valeev.





>
>
>
> On 1/22/2020 3:03 AM, Tagir Valeev wrote:
>
> Hello!
>
> It appears that it's possible to annotate record component as
> @Override or @SafeVarargs, and spec doesn't explicitly forbid this:
>
> record Test(@SafeVarargs int x, @Override int y) {}
>
> In these cases, it's assumed that the annotation propagates to the
> accessor method. However, having @SafeVarargs on the accessor method
> is prohibited, so should be in a record component. So I expect to see
> in 9.6.4.7 something like this:
>
>
> It is a compile-time error if a record component (§8.10.1) is annotated with the annotation @SafeVarargs.
>
> Having the @Override is possible on the accessor if accessor overrides
> the interface method (and it's really cool possibility!) Probably it's
> ok to allow this annotation on the record component in this case, but
> it should be definitely disallowed if the accessor doesn't override
> anything. So I expect something like this in 9.6.4.4:
>
>
> If a record component (§8.10.1) of record R is annotated with the annotation @Override and the accessor method for that component (§8.10.3) does not override a method declared in a superinterface of R (§8.4.8.1), then a compile-time error occurs.
>
> What do you think?
>
> With best regards,
> Tagir Valeev.
>
> [1] https://docs.oracle.com/javase/specs/jls/se13/html/jls-9.html#jls-9.6.4.7
> [2] https://docs.oracle.com/javase/specs/jls/se13/html/jls-9.html#jls-9.6.4.4
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.java.net/pipermail/amber-spec-experts/attachments/20200122/77d990d2/attachment.htm>