[jdk17u] RFR: 8268885: duplicate checkcast when destination type is not first type of intersection type

Wed Oct 6 15:32:27 UTC 2021

I'd like to backport JDK-8268885 to 17u. It fixes duplicate checkcasts in javac.
The patch applies cleanly.
Tested with langtools tests, updated test fails without the fix, passes with it.

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Commit messages:
 - Backport dd1209e4ae3c8e42d121329639ec4bd359d0a456

Changes: https://git.openjdk.java.net/jdk17u/pull/158/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=158&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268885
  Stats: 37 lines in 2 files changed: 24 ins; 3 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/158.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/158/head:pull/158

PR: https://git.openjdk.java.net/jdk17u/pull/158