RFR: 8371339: Illegal pattern char 'B' with locale.providers as HOST on macOS for Taiwanese

[Roger Riggs]

On Thu, 6 Nov 2025 19:35:06 GMT, Naoto Sato <naoto at openjdk.org> wrote:

> This is a leftover when we introduced "dayperiods" in the JDK ([JDK-8247781](https://bugs.openjdk.org/browse/JDK-8247781)). The CLDR Converter was modified to generate patterns for SimpleDateFormat for dayperiods (simply replacing them with ampm), and the same processing should have been applied to Host provider on mac, which also uses LDML patterns. As in the bug report, macos recently started using dayperiods, thus the issue was revealed. Regression test is not provided as it would require the macos's default locale should be configured to zh_TW. I have manually confirmed that the proposed fix would work for the problem case.

Looks good.

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Marked as reviewed by rriggs (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/28181#pullrequestreview-3456048793