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

[Vicente Romero]

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/java.base/share/classes/java/lang/runtime/SwitchBootstraps.java line 170:

> 168:             } else if (label instanceof EnumDesc<?> enumDesc) {
> 169:                 if (target.getClass().isEnum() &&
> 170:                     ((Enum<?>) target).describeConstable().stream().anyMatch(d -> d.equals(enumDesc))) {

probably a matter of style but isn't it a bit too much to use streams here? there will be always only one element right?

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PR Review Comment: https://git.openjdk.org/jdk/pull/13074#discussion_r1170784311