-XepDisableWarningsInGeneratedCode ignored by some bug checkers

[Stephan202]

The -XepDisableWarningsInGeneratedCode flag suppresses warnings inside classes annotated with @Generated. However, this logic has no effect on CompilationUnitTreeMatchers, as a CompilationUnitTree encompasses one or more classes.

For example, consider the following class:

import javax.annotation.processing.Generated;
import java.util.Map;

@Generated("foo")
class Dummy {
  private String prop;

  Dummy(String prop) {
    this.prop = prop;
  }
}

Compile this code as follows:

javac \
  -XDcompilePolicy=simple \
  -processorpath error_prone_core-2.3.2-with-dependencies.jar \
  '-Xplugin:ErrorProne -XepDisableAllChecks -XepDisableWarningsInGeneratedCode -Xep:FieldCanBeFinal:WARN -Xep:RemoveUnusedImports:WARN' \
  Dummy.java

Despite the @Generated annotation, two warnings are emitted:

Dummy.java:6: warning: [FieldCanBeFinal] This field is only assigned during initialization; consider making it final
  private String prop;
                 ^
    (see https://errorprone.info/bugpattern/FieldCanBeFinal)
  Did you mean 'private final String prop;'?
Dummy.java:2: warning: [RemoveUnusedImports] Unused imports
import java.util.Map;
^
    (see https://errorprone.info/bugpattern/RemoveUnusedImports)
  Did you mean to remove this line?
2 warnings

One possible solution would be to descend into CompilationUnitTrees to look for @Generated type declarations, and skip analysis if any are found. I wonder what the Error Prone team thinks of this approach. Maybe I'm overlooking a much more elegant and/or efficient solution.

NB: annotating a whole package as @Generated may be a workaround for this issue (didn't check), but such a workaround would in any case not be suitable for annotation processors which generate code in the same package as their "source type", like Google Auto Value or Immutables.

[dclements]

Same problem but with MethodCanBeStatic.