On Wed, 24 Jun 2026 18:47:07 GMT, Justin Lu <[email protected]> wrote:
> This PR corrects Locale parsing logic for extra languages. The BCP syntax
> enforces that extlangs may only follows `2*3 ALPHA` langs. This is also
> reinforced by the syntax comment described in `LanguageTag.parse` (which is
> based off the BNF). However, the current implementation does not respect
> this, and allows extlangs to follow `4ALPHA` (future use) as well as
> `5*8ALPHA` langs.
>
> For example, `Locale.forLanguageTag("quux-bar").toLanguageTag()` returns the
> extlang "bar" when it should return the lang "quux" and discard the extlang
> "bar".
>
> This is likely an oversight and should be fixed rather than kept and
> specified as a BCP deviation, since it is non standard for extlangs to follow
> those previously mentioned longer tags.
>
> I can file a release note if deemed warranted since the acceptable inputs
> shrink as a result (even if the correct behavior). Personally, I would lean
> towards not filing one since such occurrences would be non-standard as there
> are no extlangs that follow a non 2-3 length language prefix.
>
> ---------
> - [x] I confirm that I make this contribution in accordance with the [OpenJDK
> Interim AI Policy](https://openjdk.org/legal/ai).
LGTM
test/jdk/java/util/Locale/LocaleEnhanceTest.java line 1401:
> 1399:
> 1400: // Ensure that extlang is only accepted after a 2*3ALPHA lang
> 1401: // That is, 4 ALPHA (future use) and 5*8 ALPHA langs should not
> accept extlangs
Nit: I think it may be clearer to spell out `lang` as `language`, which is the
name used in RFC 5646.
-------------
PR Review: https://git.openjdk.org/jdk/pull/31663#pullrequestreview-4565746860
PR Review Comment: https://git.openjdk.org/jdk/pull/31663#discussion_r3470112326
