RFR: 8339644: Improve parsing of Day/Month in tzdata rules [v3]

[Naoto Sato]

On Fri, 6 Sep 2024 21:49:30 GMT, Naoto Sato <naoto at openjdk.org> wrote:

>> Fixing TZDB build tool to accommodate full month/day names. Recently released tzdb2024b included (inadvertently) full month name "April", which is allowed by the spec (zic.8), but never used. This will cause build failure of the JDK. The proposed fix is manually tested by modifying the tzdb files to include full month names, and confirmed the successful build of the JDK.
>
> Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Strictly conforming to the spec

Had to modify the fix. According to zic(8):

Names must be in English and are case insensitive.  They appear in several contexts, and include month and weekday names and keywords such as “maximum”, “only”, “Rolling”, and “Zone”.  A name can be abbreviated by omitting all but an initial prefix; any abbreviation must be unambiguous in context

Thus April can not only either "Apr" or "April", but also "apr", "april", "apri", or "Ap". The fix assumes the source tz files already have unbiguous names.

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PR Comment: https://git.openjdk.org/jdk/pull/20893#issuecomment-2334857393