RFR: 8359493: Refactor how aggregated mandatory warnings are handled in the compiler [v2]

[Archie Cobbs]

On Mon, 23 Jun 2025 21:19:37 GMT, Archie Cobbs <acobbs at openjdk.org> wrote:

>> Also, are there mandatory warnings for which there's no aggregation?
>
> Thanks for your thoughts on that. I will work on a properties file version of this so we can take a look at it. I think this should help make things as "clean" as they can be, while still preserving the existing (slightly wonky) behavior.
> 
> Regarding the JEP, there may indeed be some disagreement between what it specifies and what's implemented. If so, adding these flags to the properties file should make that disagreement (a) more obvious and (b) easy to fix.

> Also, are there mandatory warnings for which there's no aggregation?

Yes, I believe these are the only two:

`compiler.warn.sun.proprietary`
`compiler.warn.preview.feature.use.classfile`

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PR Review Comment: https://git.openjdk.org/jdk/pull/25810#discussion_r2162557517