RFR: 8367530: The exhaustiveness errors could be improved [v13]

[Maurizio Cimadamore]

On Mon, 26 Jan 2026 12:17:22 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Maybe the intent is that you don't want to just check the "depth" of the check, but also the "width" -- e.g. if there's few nested record patterns, but each has a huge number of components.
>
> Also, `isBpCovered` seems to be called by routines (like `reduceRecordPattern`) that do not seem related to the new logic (which is what got me suspicious about the location of the update to begin with). Which has (at least in theory) potential for `TooManyChecksException` to trigger in places where it's not expected? (but maybe that's handled by the special value `-1` which is carefully set after the new logic runs)

A possible suggestion might be to add this check inside `doExpandMissingPatternDescriptions` -- after the `if (toExpand instanceof BindingPattern bp) {` ?

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PR Review Comment: https://git.openjdk.org/jdk/pull/27256#discussion_r2727399031