False positive: UnusedVariable for record components that are not read directly

[anthonyvdotbe]

Description of the problem / feature request:

A false positive for UnusedVariable is reported for all record components that are only read through methods.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

class Foo {

    record Bar(int v) {}

    int baz() {
        return new Bar(42).v();
    }

}

What version of Error Prone are you using?

2.4.0

Have you found anything relevant by searching the web?

No.

[ferozco]

We built a stricter version of UnusedVariable in gradle-baseline and we were able to make the rule compatible with records with this change which should be directly applicable to UnusedVariable

[codylerum]

Same hit on this

Just the most simple record will fail

public record AgentAndCount(String agent, long count) {
}

Warning:  /home/runner/work/oss/oss/src/main/java/co/foo/oss/agent/AgentAndCount.java:[3,34] [UnusedVariable] The field 'agent' is never read.
    (see https://errorprone.info/bugpattern/UnusedVariable)
  Did you mean 'public record AgentAndCount(, long count) {'?
Warning:  /home/runner/work/oss/oss/src/main/java/co/foo/oss/agent/AgentAndCount.java:[3,46] [UnusedVariable] The field 'count' is never read.
    (see https://errorprone.info/bugpattern/UnusedVariable)
  Did you mean 'public record AgentAndCount(String agent) {'?

[tschniewind]

Please reopen, cause it still failes if record is private as in

class Foo {

  private record Bar(int v) {
  }

  int baz() {
    return new Bar(42).v();
  }

}

com.google.errorprone.error_prone_core: 2.16
JDK 17, source & target 17

[nvervelle]

Please reopen, cause it still failes if record is private as in

This is why #2713 was opened :-)