RFR: 8262891: Compiler implementation for Pattern Matching for switch (Preview) [v5]

[Jan Lahoda]

On Thu, 27 May 2021 10:38:08 GMT, Maurizio Cimadamore <mcimadamore at openjdk.org> wrote:

>> Jan Lahoda has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 12 commits:
>> 
>>  - Post-merge fix - need to include jdk.internal.javac in the list of packages used by jdk.compiler again, as we now (again) have a preview feature in javac.
>>  - Correcting LineNumberTable for rule switches.
>>  - Merging master into JDK-8262891
>>  - Fixing various error-related bugs.
>>  - Avoiding fall-through from the total case to a synthetic default but changing total patterns to default.
>>  - Reflecting recent spec changes.
>>  - Reflecting review comments.
>>  - Reflecting review comments on SwitchBootstraps.
>>  - Trailing whitespaces.
>>  - Cleanup, reflecting review comments.
>>  - ... and 2 more: https://git.openjdk.java.net/jdk/compare/083416d3...fd748501
>
> src/jdk.compiler/share/classes/com/sun/tools/javac/comp/Attr.java line 1657:
> 
>> 1655: 
>> 1656:         try {
>> 1657:             boolean enumSwitch = (seltype.tsym.flags() & Flags.ENUM) != 0;
> 
> This is getting convoluted enough that an enum on the AST (e.g. SwitchKind) might be helpful to save some of these classification properties - which I imagine we have to redo at some point later (e.g. in Lower/TransPattern). I'm ok with fixing in a followup issue.

Thanks Maurizio. Yes, some of the logic is partly repeated elsewhere, but I need to investigate how to improve that. I've filled:
https://bugs.openjdk.java.net/browse/JDK-8267929

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PR: https://git.openjdk.java.net/jdk/pull/3863