[java] CompareObjectsWithEquals / UseEqualsToCompareStrings - False negatives with fields

[adangel]

Describe the PR

Fixes false negatives in case fields are referenced with this.
Type resolution on PrimaryExpression works well enough to
simply check the type.

CompareObjectsWithEquals had the same problem. It was easier to rewrite this rule as a XPath rule.
Note: I changed one test case, which was actually wrong.

Example

public class ClassWithStringFields {
    private String string1 = "a";
    private String string2 = "a";

    public void bar() {
        if (string1 == string2) { }  // violation
        if (string1 == this.string2) { } // violation - FN
        if (this.string1 == string2) { } // violation - FN
        if (this.string1 == this.string2) { } // violation - FN

        if (string1 != string2) { } // violation
        if (string1 != this.string2) { } // violation - FN
        if (this.string1 != string2) { } // violation - FN
        if (this.string1 != this.string2) { } // violation - FN

        if (string1.equals(string2)) { } // ok
        if (this.string1.equals(string2)) { } // ok
        if (string1.equals(this.string2)) { } // ok
        if (this.string1.equals(this.string2)) { } // ok
    }
}

Related issues

• None

Ready?

• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by travis)
• Release Notes
• Get regression tester report working (should show new violations)

[pmd-test]

	1 Message
📖	This changeset introduces 357 new violations, 0 new errors and 0 new configuration errors, removes 55 violations, 0 errors and 2 configuration errors. Full report
✅	This changeset introduces 548 new violations, 0 new errors and 0 new configuration errors, removes 50 violations, 0 errors and 2 configuration errors. Full report
✅	This changeset introduces 1303 new violations, 0 new errors and 0 new configuration errors, removes 38 violations, 0 errors and 2 configuration errors. Full report
✅	This changeset introduces 1517 new violations, 0 new errors and 0 new configuration errors, removes 38 violations, 0 errors and 2 configuration errors. Full report
✅	This changeset introduces 13531 new violations, 0 new errors and 0 new configuration errors, removes 38 violations, 0 errors and 2 configuration errors. Full report

Generated by 🚫 Danger

[adangel]

Running pmdtester failed, this message is mainly used to remind the maintainers of PMD.

From the logs:

--2020-11-19 21:32:50-- https://master.dl.sourceforge.net/project/pmd/pmd-regression-tester/master-baseline.zip
Resolving master.dl.sourceforge.net (master.dl.sourceforge.net)... 216.105.38.12
Connecting to master.dl.sourceforge.net (master.dl.sourceforge.net)|216.105.38.12|:443... connected.
HTTP request sent, awaiting response... 503 Service Unavailable
2020-11-19 21:32:50 ERROR 503: Service Unavailable.

regression tester was unable to download the master baseline from sourceforge.... I hope, that's only a temporary problem.

[adangel]

regression tester was unable to download the master baseline from sourceforge.... I hope, that's only a temporary problem.

Seems like there are some issues atm - see https://sourceforge.net/p/forge/site-support/21502/

I could resolve it now by deleting the baseline and re-uploading it. That triggered the mirroring again and the download worked:
https://sourceforge.net/projects/pmd/files/pmd-regression-tester/master-baseline.zip/download

[oowekyala]

Looks good. I'll merge into master and incorporate these improvements into #2899