[jira] [Created] (GROOVY-7954) Equal Operator for Classes implementing Comparable not Working on Interfaces

["Josef (JIRA)" <ji...@apache.org>]

Josef created GROOVY-7954:
-----------------------------

             Summary: Equal Operator for Classes implementing Comparable not Working on Interfaces
                 Key: GROOVY-7954
                 URL: https://issues.apache.org/jira/browse/GROOVY-7954
             Project: Groovy
          Issue Type: Bug
          Components: groovy-runtime
    Affects Versions: 2.4.7
         Environment: Windows 10, Java 7
            Reporter: Josef


Using the equal operator "==" on two instances A and B does not work correctly, when

1) A and B implement the same interface I1 but are not the same class and
2) interface I1 extends the "Comparable" interface.

The checking in DefaultTypeTransformation.compareToWithEqualityCheck(...) checks for assignable classes, and uses compareTo when assignable on class level (which is not the case for instance A and B). But it does not check on interface level.

That way, calling the compareTo(..) method is not performed.
In my use case, class A and B are actually considered equal, even so their concrete implementation is different. And the compareTo(...) method would actually return 0. 

How about doing real equality checking instead of returning -1 close to the end of method DefaultTypeTransformation.compareToWithEqualityCheck(...):

...
if (equalityCheckOnly) {
    return left.equals(right) ? 0 : -1;
}

throw new GroovyRuntimeException("Cannot compare " + left.getClass().getName() + " with value '" +
                left + "' and " + right.getClass().getName() + " with value '" + right + "'");

Thanks for your effort.



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