RFR: 8262889: Compiler implementation for Record Patterns [v2]

[Jan Lahoda]

> 8262889: Compiler implementation for Record Patterns
> 
> A first version of a patch that introduces record patterns into javac as a preview feature. For the specification, please see:
> http://cr.openjdk.java.net/~gbierman/jep427+405/jep427+405-20220426/specs/patterns-switch-record-patterns-jls.html
> 
> There are two notable tricky parts:
> -in the parser, it was necessary to improve the `analyzePattern` method to handle nested/record patterns, while still keeping error recovery reasonable
> -in the `TransPatterns`, the desugaring of the record patterns is very straightforward - effectivelly the record patterns are desugared into guards/conditions. This will likely be improved in some future version/preview
> 
> `MatchException` has been extended to cover additional cases related to record patterns.

Jan Lahoda has updated the pull request incrementally with one additional commit since the last revision:

  Reflecting review feedback.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/8516/files
  - new: https://git.openjdk.java.net/jdk/pull/8516/files/56020b0b..90b37c3a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=8516&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=8516&range=00-01

  Stats: 193 lines in 18 files changed: 67 ins; 19 del; 107 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8516.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8516/head:pull/8516

PR: https://git.openjdk.java.net/jdk/pull/8516