[java] False positive for UseInstanceofToCompareClasses on local generic class

[oowekyala]

UseInstanceofToCompareClasses reports on non-reifiable types, even though they're not acceptable as operand to instanceof. E.g.:

class Foo<T> {

public Foo<T> wrap() {
   // since the local class is not static, the T here refers to the T of the outer instance
   class MyWrapper extends Foo<T> {
      
   }
   this instanceof MyWrapper // -> error, MyWrapper is not reifiable, because its supertype Foo<T> isn't 

   this.getClass().equals(MyWrapper.class) // this is the only way to compare it
} 

}

[jsotuyod]

This is actually an internal rule defined by us in our dogfood ruleset, so I move the issue here instead

build-tools/src/main/resources/net/sourceforge/pmd/pmd-dogfood-config.xml

Lines 515 to 533 in dc0c494

	<rule name="UseInstanceofToCompareClasses"
	language="java"
	since="5.0"
	message="replace o.getClass().equals(MyClass.class) with o instanceof MyClass"
	class="net.sourceforge.pmd.lang.rule.xpath.XPathRule">
	<description>replace o.getClass().equals(MyClass.class) with o instanceof MyClass. Make sure MyClass doesn't have descendants</description>
	<priority>1</priority>
	<properties>
	<property name="xpath">
	<value>
	<![CDATA[
	//MethodCall[pmd-java:matchesSig("_#equals(java.lang.Object)")]
	[MethodCall[pmd-java:matchesSig("_#getClass()")]]
	[ArgumentList/ClassLiteral]
	]]>
	</value>
	</property>
	</properties>
	</rule>