[java] Resolve StackOverflow in JavaTypeDefinitionSimple.toString()

- Resolves #831

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

@@ -158,4 +158,6 @@ public abstract class JavaTypeDefinition implements TypeDefinition {
     public abstract JavaTypeDefinition getJavaType(int index);
 
     public abstract int getJavaTypeCount();
+
+    protected abstract String shallowString();
 }

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

@@ -21,8 +21,10 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.function.Function;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import java.util.stream.Collectors;
 
 
 /* default */ class JavaTypeDefinitionSimple extends JavaTypeDefinition {
@@ -243,7 +245,21 @@ import java.util.logging.Logger;
     public String toString() {
         return new StringBuilder("JavaTypeDefinition [clazz=").append(clazz)
                 .append(", definitionType=").append(getDefinitionType())
-                .append(", genericArgs=").append(genericArgs)
+                .append(", genericArgs=").append(genericArgs.stream().map(new Function<JavaTypeDefinition, String>() {
+
+                    @Override
+                    public String apply(final JavaTypeDefinition jtd) {
+                        return jtd.shallowString();
+                    }
+                }).collect(Collectors.toList()))
+                .append(", isGeneric=").append(isGeneric)
+                .append("]\n").toString();
+    }
+    
+    @Override
+    public String shallowString() {
+        return new StringBuilder("JavaTypeDefinition [clazz=").append(clazz)
+                .append(", definitionType=").append(getDefinitionType())
                 .append(", isGeneric=").append(isGeneric)
                 .append("]\n").toString();
     }

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

@@ -111,15 +111,20 @@ import java.util.Set;
     public String toString() {
         StringBuilder builder = new StringBuilder()
                 .append("JavaTypeDefinition ")
-                .append(getDefinitionType().toString())
+                .append(getDefinitionType())
                 .append(" [")
                 .append(typeList[0]);
         for (int index = 1; index < typeList.length; ++index) {
-            builder.append(" && ");
-            builder.append(typeList[index]);
+            builder.append(" && ")
+                .append(typeList[index]);
         }
         return builder.append("]").toString();
     }
+    
+    @Override
+    protected String shallowString() {
+        return toString();
+    }
 
     @Override
     public boolean equals(Object obj) {

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

@@ -102,6 +102,7 @@ import net.sourceforge.pmd.typeresolution.testdata.MethodThirdPhase;
 import net.sourceforge.pmd.typeresolution.testdata.NestedAnonymousClass;
 import net.sourceforge.pmd.typeresolution.testdata.Operators;
 import net.sourceforge.pmd.typeresolution.testdata.OverloadedMethodsUsage;
+import net.sourceforge.pmd.typeresolution.testdata.PmdStackOverflow;
 import net.sourceforge.pmd.typeresolution.testdata.Promotion;
 import net.sourceforge.pmd.typeresolution.testdata.SubTypeUsage;
 import net.sourceforge.pmd.typeresolution.testdata.SuperExpression;
@@ -123,6 +124,12 @@ import net.sourceforge.pmd.typeresolution.testdata.dummytypes.SuperClassB2;
 
 public class ClassTypeResolverTest {
 
+    @Test
+    public void stackOverflowTest() {
+        // See #831 https://github.com/pmd/pmd/issues/831 - [java] StackOverflow in JavaTypeDefinitionSimple.toString
+        parseAndTypeResolveForClass15(PmdStackOverflow.class);
+    }
+    
     @Test
     public void testClassNameExists() {
         ClassTypeResolver classTypeResolver = new ClassTypeResolver();

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

@@ -0,0 +1,47 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.typeresolution.testdata;
+
+public class PmdStackOverflow {
+
+    public void shouldThrowStackOverfloError() {
+        MessageBuilder messageBuilder = new MessageBuilderA();
+
+        // Works
+        PartBuilder partBuilder = messageBuilder.newComponent();
+        messageBuilder.addComponent(partBuilder.withSomeValue("ABC"));
+
+        // Does not work
+        messageBuilder.addComponent(messageBuilder.newComponent().withSomeValue("ABC"));
+    }
+
+}
+
+abstract class MessageBuilder<T extends MessageBuilder, U extends PartBuilder<U>> {
+
+    public abstract U newComponent();
+
+    public T addComponent(U ignore) {
+        return (T) this;
+    }
+}
+
+class MessageBuilderA extends MessageBuilder<MessageBuilderA, PartBuilderA> {
+
+    @Override
+    public PartBuilderA newComponent() {
+        return new PartBuilderA();
+    }
+}
+
+class PartBuilder<T extends PartBuilder> {
+
+    public T withSomeValue(String ignore) {
+        return (T) this;
+    }
+}
+
+class PartBuilderA extends PartBuilder<PartBuilderA> {
+}