Fix anonymous classes directly from interfaces

- Fix the failing scenarios such as new Comaprator<String>() {...

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/typeresolution/typedefinition/JavaTypeDefinition.java

@@ -26,9 +26,14 @@ public class JavaTypeDefinition implements TypeDefinition {
         this.clazz = clazz;
 
         final TypeVariable<?>[] typeParameters;
+        // the anonymous class can't have generics, but we may be binding generics from super classes
         if (clazz.isAnonymousClass()) {
-            // the anonymous class can't have generics, but we may be bounding generics from super classes
-            typeParameters = resolveTypeDefinition(clazz.getGenericSuperclass()).clazz.getTypeParameters();
+            // is this an anonymous class based on an interface or a class?
+            if (clazz.getSuperclass() == Object.class) {
+                typeParameters = clazz.getInterfaces()[0].getTypeParameters();
+            } else {
+                typeParameters = clazz.getSuperclass().getTypeParameters();
+            }
         } else {
             typeParameters = clazz.getTypeParameters();
         }
@@ -54,7 +59,7 @@ public class JavaTypeDefinition implements TypeDefinition {
         }
         
         final JavaTypeDefinition newDef = new JavaTypeDefinition(clazz);
-        
+
         // We can only cache types without generics, since their values are context-based
         if (!newDef.isGeneric) {
             CLASS_TYPE_DEF_CACHE.put(clazz, newDef);
@@ -64,13 +69,13 @@ public class JavaTypeDefinition implements TypeDefinition {
     }
     
     public static JavaTypeDefinition forClass(final Class<?> clazz, final JavaTypeDefinition... boundGenerics) {
-        // With generics there is no cache
-        final JavaTypeDefinition typeDef = forClass(clazz);
-        
-        if (typeDef == null) {
+        if (clazz == null) {
             return null;
         }
         
+        // With generics there is no cache
+        final JavaTypeDefinition typeDef = new JavaTypeDefinition(clazz);
+
         for (final JavaTypeDefinition generic : boundGenerics) {
             typeDef.genericArgs.add(generic);
         }

pmd-java/src/test/java/net/sourceforge/pmd/typeresolution/ClassTypeResolverTest.java

@@ -12,6 +12,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.StringReader;
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.List;
 import java.util.StringTokenizer;
 
@@ -49,6 +50,7 @@ import net.sourceforge.pmd.lang.java.ast.TypeNode;
 import net.sourceforge.pmd.lang.java.symboltable.VariableNameDeclaration;
 import net.sourceforge.pmd.lang.java.typeresolution.ClassTypeResolver;
 import net.sourceforge.pmd.lang.java.typeresolution.typedefinition.JavaTypeDefinition;
+import net.sourceforge.pmd.typeresolution.testdata.AnonymousClassFromInterface;
 import net.sourceforge.pmd.typeresolution.testdata.AnonymousInnerClass;
 import net.sourceforge.pmd.typeresolution.testdata.ArrayListFound;
 import net.sourceforge.pmd.typeresolution.testdata.DefaultJavaLangImport;
@@ -170,6 +172,15 @@ public class ClassTypeResolverTest {
         Assert.assertTrue(statement.isReferenceToClassSameCompilationUnit());
     }
 
+    @Test
+    public void testAnonymousClassFromInterface() throws Exception {
+        Node acu = parseAndTypeResolveForClass(AnonymousClassFromInterface.class, "1.8");
+        ASTAllocationExpression allocationExpression = acu.getFirstDescendantOfType(ASTAllocationExpression.class);
+        TypeNode child = (TypeNode) allocationExpression.jjtGetChild(0);
+        Assert.assertTrue(Comparator.class.isAssignableFrom(child.getType()));
+        Assert.assertSame(Integer.class, child.getTypeDefinition().getGenericType(0).getType());
+    }
+
     @Test
     public void testAnonymousInnerClass() throws ClassNotFoundException {
         ASTCompilationUnit acu = parseAndTypeResolveForClass15(AnonymousInnerClass.class);

pmd-java/src/test/java/net/sourceforge/pmd/typeresolution/testdata/AnonymousClassFromInterface.java

@@ -0,0 +1,17 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.typeresolution.testdata;
+
+import java.util.Comparator;
+
+public class AnonymousClassFromInterface {
+
+    public Comparator<Integer> comparator = new Comparator<Integer>() {
+        @Override
+        public int compare(Integer o1, Integer o2) {
+            return 0;
+        }
+    };
+}