RFR: 8300543 Compiler Implementation for Pattern Matching for switch [v2]

Maurizio Cimadamore mcimadamore at openjdk.org
Tue Apr 18 13:15:54 UTC 2023

On Tue, 18 Apr 2023 09:13:01 GMT, Jan Lahoda <jlahoda at openjdk.org> wrote:

>> This is the first draft of a patch for JEP 440 and JEP 441. Changes included:
>>  - the pattern matching for switch and record patterns features are made final, together with updates to tests.
>>  - parenthesized patterns are removed.
>>  - qualified enum constants are supported for case labels.
>> This change herein also includes removal record patterns in for each loop, which may be split into a separate PR in the future.
> Jan Lahoda has updated the pull request incrementally with six additional commits since the last revision:
>  - Fixing infinite loop where a binding pattern is replaced with a binding pattern for the same type.
>  - Reflecting review comments.
>  - Fixing exhaustiveness for unsealed supertype pattern.
>  - No need to enable features after error reported.
>  - SwitchBootstraps.typeSwitch should not initialize enum classes.
>  - A prototype of avoiding enum initialization.

src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Flow.java line 953:

> 951:                     }
> 952: 
> 953:                     Set<PatternDescription> cleanedToRemove = new HashSet<>(toRemove);

Another way to do this would be to compute the intersection between `toRemove` and `toAdd` (e.g. with `retainAll`), and then remove the intersection from both sets.


PR Review Comment: https://git.openjdk.org/jdk/pull/13074#discussion_r1169854290

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