Integrated: 8343306: javac is failing to determine if a class and a sealed interface are disjoint

[Vicente Romero]

On Wed, 30 Oct 2024 20:48:27 GMT, Vicente Romero <vromero at openjdk.org> wrote:

> For code like:
> 
> 
> class Test {
>     sealed interface I permits C1 {}
>     non-sealed class C1 implements I {}
>     class C2 extends C1 {}
>     class C3 {}
>     I m(int s, C3 c3) {
>         I i = (I)c3;
>     }
> }
> 
> javac is failing to issue an error and accepts this code. The spec is clear stating that code like this should be rejected. See:
> 
> 5.1.6.1 Allowed Narrowing Reference Conversion:
> 
> • A class named C is disjoint from an interface named I if (i) it is not the case that
>   C <: I , and (ii) one of the following cases applies:
>   – C is freely extensible (§8.1.1.2), and I is sealed , and C is disjoint from all of
>   the permitted direct subclasses and subinterfaces of I .
> 
> and just below it continues:
> • A class named C is disjoint from another class named D if (i) it is not the case
> that C <: D , and (ii) it is not the case that D <: C .
> 
> so here we have the `C3` is a freely extensible class and interface `I` is sealed and `C3` is disjoint from `C1` which is is the permitted subclass of interface `I`
> 
> This PR should sync javac with the spec
> 
> TIA

This pull request has now been integrated.

Changeset: 96eed7fa
Author:    Vicente Romero <vromero at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/96eed7fa6c025374bc10039bca2949a76d78f890
Stats:     69 lines in 2 files changed: 45 ins; 0 del; 24 mod

8343306: javac is failing to determine if a class and a sealed interface are disjoint

Reviewed-by: jlahoda, mcimadamore

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PR: https://git.openjdk.org/jdk/pull/21794