[jdk17] RFR: 8269146: Missing unreported constraints on pattern and other case label combination [v2]

[Maurizio Cimadamore]

On Thu, 1 Jul 2021 13:26:25 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

>> There is a number of constraints on the case label forms - patterns cannot be combined with patterns, etc. Currently, the checks are implemented by checking if there are clashing bindings. But this misses some of the cases which should lead to errors. This patch proposes to implement explicit checks on the structure of the case labels in `Attr.handleSwitch`, rather than relying on clashing bindings.
>
> Jan Lahoda has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fixing fallthrough.

Approving for now, perhaps with a view to investigate ways to split the checks at a later point.

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Marked as reviewed by mcimadamore (Reviewer).

PR: https://git.openjdk.java.net/jdk17/pull/194