MutableException check fails with NPE if extended class is in canonical form

[mkordas]

MutableException check fails with NullPointerException if extended class is in canonical form.

Configuration

<module name="MutableException"/>

Input file

class CustomException extends java.lang.Exception {}

Stacktrace

java.lang.NullPointerException
        at com.puppycrawl.tools.checkstyle.checks.design.MutableExceptionCheck.isExtendedClassNamedAsException(MutableExceptionCheck.java:155)
        at com.puppycrawl.tools.checkstyle.checks.design.MutableExceptionCheck.visitClassDef(MutableExceptionCheck.java:114)
        at com.puppycrawl.tools.checkstyle.checks.design.MutableExceptionCheck.visitToken(MutableExceptionCheck.java:91)
        at com.puppycrawl.tools.checkstyle.TreeWalker.notifyVisit(TreeWalker.java:393)
        at com.puppycrawl.tools.checkstyle.TreeWalker.processIter(TreeWalker.java:482)
        at com.puppycrawl.tools.checkstyle.TreeWalker.walk(TreeWalker.java:322)
        at com.puppycrawl.tools.checkstyle.TreeWalker.processFiltered(TreeWalker.java:195)
        at com.puppycrawl.tools.checkstyle.api.AbstractFileSetCheck.process(AbstractFileSetCheck.java:76)
        at com.puppycrawl.tools.checkstyle.Checker.process(Checker.java:260)

[romani]

Pleaese let me know name of opensource project where you found such code, we might use it in checkstyle-checker.

[mkordas]

It's the project we already use - Findbugs.

[romani]

Hmm, i checked it on 6.6 it worked fine, so i put priority Hight. I will think how to can make huge regression testing on each commit.

[Vladlis]

Sorry, this is my fault
#1103

[romani]

merged.

[romani]

@Vladlis, on any next PR from you, please test by checkstyle-tester all your changes, and confirm that there is no Errors after your changes for "dead code".

[mkordas]

This issue needs to be reopened. In this case removing "dead" code and then having NPE was VERY valuable, as it revealed missing implementation for canonical class names. Adding null check hid the issue once again.
I'll provide failing test and new implementation shortly.

[romani]

I keep it close, as you already fixed it.