<i18n dev> Integrated: 8368981: Case Fold Locale Legacy Tags On Demand

[Justin Lu]

On Wed, 1 Oct 2025 21:11:53 GMT, Justin Lu <jlu at openjdk.org> wrote:

> Please review this PR which case folds grandfathered BCP47 tags on demand. (Instead of keeping the case compliant versions stored.)
> 
> This facilitates the cleanup of the `LEGACY` map (which contains a String to String Array mapping). The 2D String array, creation and populating of the  `LEGACY` map, as well as lower case folding of the legacy tags can now be removed from the static block of _sun.util.locale.LanguageTag_.
> 
> Legacy tags are a small subset compared to the entire set of valid BCP47 tags. Reducing the cost for supporting them would be ideal. Instead, legacy tags can now be checked against and folded on demand via a switch statement.
> 
> The commented grandfathered syntax is removed because the values themselves already exist as code, and the exact case can be found in the provided RFC link.

This pull request has now been integrated.

Changeset: 23a65644
Author:    Justin Lu <jlu at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/23a65644ae63b271ca99c55a2a60a192c4e4dfb8
Stats:     208 lines in 2 files changed: 100 ins; 90 del; 18 mod

8368981: Case Fold Locale Legacy Tags On Demand

Reviewed-by: rriggs, naoto

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PR: https://git.openjdk.org/jdk/pull/27596