UnnecessarySemicolonAfterTypeMemberDeclaration throws Exception on on Local Class

[nrmancuso]

I have read check documentation: https://checkstyle.sourceforge.io/checks/coding/unnecessarysemicolonaftertypememberdeclaration.html#UnnecessarySemicolonAfterTypeMemberDeclaration
I have downloaded the latest checkstyle from: https://checkstyle.org/cmdline.html#Download_and_Run
I have executed the cli and showed it below, as cli describes the problem better than 1,000 words

➜  src javac SwitchScope.java 

➜  src cat SwitchScope.java 
public class SwitchScope {
    public static void main(String[] args) {
        switch (args.length) {
        case 0:
            final int k = 12;
            class Local {
                int j = k;
            }
        case 1:
        }
    }
}
                                                                                                           
➜  src cat config.xml 
<?xml version="1.0"?>
<!DOCTYPE module PUBLIC
    "-//Checkstyle//DTD Checkstyle Configuration 1.3//EN"
    "https://checkstyle.org/dtds/configuration_1_3.dtd">
<module name="Checker">
  <property name="severity" value="error"/>
  <property name="fileExtensions" value="java, properties, xml"/>
  <module name="TreeWalker">
    <module name="UnnecessarySemicolonAfterTypeMemberDeclaration"/>
 </module>
</module>

➜  src java -jar checkstyle-10.12.1-all.jar -c config.xml SwitchScope.java 
Starting audit...
com.puppycrawl.tools.checkstyle.api.CheckstyleException: Exception was thrown while processing SwitchScope.java
        at com.puppycrawl.tools.checkstyle.Checker.processFiles(Checker.java:306)
        at com.puppycrawl.tools.checkstyle.Checker.process(Checker.java:223)
        at com.puppycrawl.tools.checkstyle.Main.runCheckstyle(Main.java:415)
        at com.puppycrawl.tools.checkstyle.Main.runCli(Main.java:338)
        at com.puppycrawl.tools.checkstyle.Main.execute(Main.java:195)
        at com.puppycrawl.tools.checkstyle.Main.main(Main.java:130)
Caused by: java.lang.NullPointerException: Cannot invoke "com.puppycrawl.tools.checkstyle.api.DetailAST.getType()" because "ast" is null
        at com.puppycrawl.tools.checkstyle.checks.coding.UnnecessarySemicolonAfterTypeMemberDeclarationCheck.isSemicolon(UnnecessarySemicolonAfterTypeMemberDeclarationCheck.java:236)
        at com.puppycrawl.tools.checkstyle.checks.coding.UnnecessarySemicolonAfterTypeMemberDeclarationCheck.checkTypeDefinition(UnnecessarySemicolonAfterTypeMemberDeclarationCheck.java:196)
        at com.puppycrawl.tools.checkstyle.checks.coding.UnnecessarySemicolonAfterTypeMemberDeclarationCheck.visitToken(UnnecessarySemicolonAfterTypeMemberDeclarationCheck.java:165)
        at com.puppycrawl.tools.checkstyle.TreeWalker.notifyVisit(TreeWalker.java:335)
        at com.puppycrawl.tools.checkstyle.TreeWalker.processIter(TreeWalker.java:406)
        at com.puppycrawl.tools.checkstyle.TreeWalker.walk(TreeWalker.java:273)
        at com.puppycrawl.tools.checkstyle.TreeWalker.processFiltered(TreeWalker.java:154)
        at com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck.process(AbstractFileSetCheck.java:98)
        at com.puppycrawl.tools.checkstyle.Checker.processFile(Checker.java:334)
        at com.puppycrawl.tools.checkstyle.Checker.processFiles(Checker.java:293)
        ... 5 more
Checkstyle ends with 1 errors.

---

Describe what you expect in detail.

I would expect this check not to throw a Null Pointer Exception on a local class declaration within a switch statement, even if this code is unusual.

[hariomch1]

Can i work on this?

[relentless-pursuit]

I have figured out where the null check can be done. Can i be assigned this?

[relentless-pursuit]

First, I tried to reproduce an issue by creating a Test.java which actually replicates the issue and a config file. And, I got a nullpointer exception as seen below.

piyush@ Development % java -jar checkstyle-10.12.2-SNAPSHOT-all.jar -c config.xml Test.java
Starting audit...
com.puppycrawl.tools.checkstyle.api.CheckstyleException: Exception was thrown while processing Test.java
	at com.puppycrawl.tools.checkstyle.Checker.processFiles(Checker.java:306)
	at com.puppycrawl.tools.checkstyle.Checker.process(Checker.java:223)
	at com.puppycrawl.tools.checkstyle.Main.runCheckstyle(Main.java:415)
	at com.puppycrawl.tools.checkstyle.Main.runCli(Main.java:338)
	at com.puppycrawl.tools.checkstyle.Main.execute(Main.java:195)
	at com.puppycrawl.tools.checkstyle.Main.main(Main.java:130)
Caused by: java.lang.NullPointerException: Cannot invoke "com.puppycrawl.tools.checkstyle.api.DetailAST.getType()" because "ast" is null
	at com.puppycrawl.tools.checkstyle.checks.coding.UnnecessarySemicolonAfterTypeMemberDeclarationCheck.isSemicolon(UnnecessarySemicolonAfterTypeMemberDeclarationCheck.java:236)
	at com.puppycrawl.tools.checkstyle.checks.coding.UnnecessarySemicolonAfterTypeMemberDeclarationCheck.checkTypeDefinition(UnnecessarySemicolonAfterTypeMemberDeclarationCheck.java:196)
	at com.puppycrawl.tools.checkstyle.checks.coding.UnnecessarySemicolonAfterTypeMemberDeclarationCheck.visitToken(UnnecessarySemicolonAfterTypeMemberDeclarationCheck.java:165)
	at com.puppycrawl.tools.checkstyle.TreeWalker.notifyVisit(TreeWalker.java:335)
	at com.puppycrawl.tools.checkstyle.TreeWalker.processIter(TreeWalker.java:406)
	at com.puppycrawl.tools.checkstyle.TreeWalker.walk(TreeWalker.java:273)
	at com.puppycrawl.tools.checkstyle.TreeWalker.processFiltered(TreeWalker.java:154)
	at com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck.process(AbstractFileSetCheck.java:98)
	at com.puppycrawl.tools.checkstyle.Checker.processFile(Checker.java:334)
	at com.puppycrawl.tools.checkstyle.Checker.processFiles(Checker.java:293)
	... 5 more
Checkstyle ends with 1 errors.

After, i implemented the null-check, I get the following output without any nullpointer exception.

piyush@ Development % java -jar checkstyle-10.12.2-SNAPSHOT-all.jar -c config.xml Test.java
Starting audit...
Audit done.

Is it good enough? And, can i proceed with a draft PR or a PR?

[nrmancuso]

Anyone is welcome to send a PR, please make a comment "I am on it" in this issue to let others know you are working on it.

[relentless-pursuit]

Anyone is welcome to send a PR, please make a comment "I am on it" in this issue to let others know you are working on it.

Thank you. I am on it.

[relentless-pursuit]

@nrmancuso i have added PR. But, it is failing the CIs. Not sure why. I just made a simple change though.

[nrmancuso]

Closed via #13486