NeedBraces: False Positives for LITERAL_CASE and LITERAL_DEFAULT

[gkeighren]

https://checkstyle.org/config_blocks.html#NeedBraces

/var/tmp $ javac NeedBracesSwitchTest.java

/var/tmp $ cat NeedBracesSwitchTest.java

public class NeedBracesSwitchTest {

  // NeedBraces should not raise any violations for this code
  // Violation raised by Checkstyle 6.4+

  // Specific cases tested:
  // Raises violation: 8.0, 7.8.2, 7.7, 7.6, 7.5.1, 6.19, 6.7, 6.4.1, 6.4
  // No violations: 5.9, 6.1, 6.2, 6.3

  public String aMethod(int val) {
      switch (val) {
              case 0: {
                      return "zero";
                  }
              case 1: {
                      return "one";
                  }
              default: {
                      return "non-binary";
                  }
          }
  }

}

/var/tmp $ cat config.xml

<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
        "-//Puppy Crawl//DTD Check Configuration 1.3//EN"
        "http://checkstyle.sourceforge.net/dtds/configuration_1_3.dtd">
<module name="Checker">
    <module name="TreeWalker">
        <module name="NeedBraces">
            <property name="tokens" value="LITERAL_CASE, LITERAL_DEFAULT"/>
        </module>
    </module>
</module>

/var/tmp $ java -jar checkstyle-8.0-all.jar -c config.xml NeedBracesSwitchTest.java

Starting audit...
[ERROR] C:\Users\gavin.keighren\Desktop\NeedBracesSwitchTest.java:12: 'case' construct must use '{}'s. [NeedBraces]
[ERROR] C:\Users\gavin.keighren\Desktop\NeedBracesSwitchTest.java:15: 'case' construct must use '{}'s. [NeedBraces]
[ERROR] C:\Users\gavin.keighren\Desktop\NeedBracesSwitchTest.java:18: 'default' construct must use '{}'s. [NeedBraces]
Audit done.
Checkstyle ends with 3 errors.

/var/tmp $ java -jar checkstyle-6.4-all.jar -c config.xml NeedBracesSwitchTest.java
Starting audit...
C:\Users\gavin.keighren\Desktop\NeedBracesSwitchTest.java:12: 'case' construct must use '{}'s.
C:\Users\gavin.keighren\Desktop\NeedBracesSwitchTest.java:15: 'case' construct must use '{}'s.
C:\Users\gavin.keighren\Desktop\NeedBracesSwitchTest.java:18: 'default' construct must use '{}'s.
Audit done.

/var/tmp $ java -jar checkstyle-6.3-all.jar -c config.xml NeedBracesSwitchTest.java
Starting audit...
Audit done.

---

I expect no violations reported. Based on local testing, the incorrect violations started being reported with Checkstyle 6.4. Please see comment in java test file for list of locally tested versions and the results.

[rnveach]

the incorrect violations started being reported with Checkstyle 6.4

Though we don't specify when acceptable tokens were added in our documentation at http://checkstyle.sourceforge.net/config_blocks.html#NeedBraces , case and default were not added as acceptable tokens until abe2b20#diff-95edbb4da33f2c258c9d24deab6b19ec which was 6.4.
Before this commit, acceptable tokens was same as default tokens which didn't list case and default.
So 6.3 or prior was never intended to support case and default.

I'm not sure why there is no error specifying the tokens being used weren't acceptable when doing regression with 6.3, but it must be a bug of some kind in old code as there will be an error in 6.4 if it was not part of acceptable. It was probably all part of the same commit that fixed this.

[romani]

Fix is merged