Fix duplicate traversal in inheritance traversing for overridden nodes.

monticore-generator/src/main/java/de/monticore/codegen/cd2java/_visitor/InheritanceHandlerDecorator.java

@@ -20,7 +20,9 @@
 import de.se_rwth.commons.Joiners;
 
 import java.util.ArrayList;
+import java.util.LinkedHashSet;
 import java.util.List;
+import java.util.Set;
 import java.util.stream.Collectors;
 
 import static de.monticore.cd.codegen.CD2JavaTemplates.ANNOTATIONS;
@@ -100,10 +102,10 @@ protected List<ASTCDMethod> getASTHandleMethods(ASTCDDefinition astcdDefinition,
   protected ASTCDMethod   getASTHandleMethod(ASTCDClass astcdClass, String languageInterfaceName, String handlerSimpleTypeName) {
     ASTCDMethod handleMethod = visitorService.getVisitorMethod(HANDLE,
             getMCTypeFacade().createQualifiedType(Joiners.DOT.join(visitorService.getASTPackage(), astcdClass.getName())));
-    List<String> superTypeList = new ArrayList<>();
+    Set<String> superTypeList = new LinkedHashSet<>();
     // super classes
     if (astcdClass.isPresentCDExtendUsage() && !astcdClass.printSuperclasses().isEmpty()) {
-      superTypeList= visitorService.getAllSuperClassesTransitive(astcdClass);
+      superTypeList.addAll(visitorService.getAllSuperClassesTransitive(astcdClass));
     }
     // super interfaces
     superTypeList.addAll(visitorService.getAllSuperInterfacesTransitive(astcdClass.getSymbol()));

monticore-test/it/src/main/grammars/mc/feature/visitor/Sub.mc4

@@ -6,6 +6,9 @@ grammar Sub extends mc.feature.visitor.Sup {
 
   E = B;
 
-  B = "test2";
+  B = "test2" NodeImpl?;
+
+  @Override
+  NodeImpl implements SomeNode = "NodeOverride";
 
 }

monticore-test/it/src/main/grammars/mc/feature/visitor/Sup.mc4

@@ -8,4 +8,8 @@ component grammar Sup extends mc.common.Basics {
 
   A = "test1" E;
 
+  interface SomeNode;
+
+  NodeImpl implements SomeNode = "NodeImpl";
+
 }

monticore-test/it/src/main/java/mc/feature/visitor/NodeCounter.java

@@ -0,0 +1,25 @@
+/* (c) https://github.com/MontiCore/monticore */
+
+package mc.feature.visitor;
+
+import mc.feature.visitor.sup._ast.ASTSomeNode;
+import mc.feature.visitor.sup._visitor.SupVisitor2;
+
+public class NodeCounter implements SupVisitor2 {
+
+  protected int num = 0;
+
+  @Override
+  public void visit(ASTSomeNode node) {
+    num++;
+  }
+
+  public int getNum() {
+    return num;
+  }
+
+  public void setNum(int num) {
+    this.num = num;
+  }
+
+}

monticore-test/it/src/test/java/mc/feature/visitor/VisitorTest.java

@@ -18,6 +18,7 @@
 import de.se_rwth.commons.logging.Log;
 import mc.GeneratorIntegrationsTest;
 import mc.feature.visitor.sub.SubMill;
+import mc.feature.visitor.sub._ast.ASTE;
 import mc.feature.visitor.sub._parser.SubParser;
 import mc.feature.visitor.sub._visitor.SubTraverser;
 import mc.feature.visitor.sup._ast.ASTA;
@@ -58,4 +59,33 @@ public void testConcreteVisitor() throws IOException {
     Assertions.assertTrue(Log.getFindings().isEmpty());
   }
 
+
+  @Test
+  public void testInheritanceTraversal() throws IOException {
+    SubParser p = new SubParser();
+    Optional<ASTE> node = p.parse_String("test2 NodeOverride");
+    Assertions.assertFalse(p.hasErrors());
+    Assertions.assertTrue(node.isPresent());
+
+    // init with plain traverser
+    SubTraverser t1 = SubMill.traverser();
+    NodeCounter c1 = new NodeCounter();
+    t1.add4Sup(c1);
+
+    // plain traverser should not reach the interface implementation
+    node.get().accept(t1);
+    Assertions.assertEquals(0, c1.getNum());
+
+
+    // init with inheritance traverser
+    SubTraverser t2 = SubMill.inheritanceTraverser();
+    NodeCounter c2 = new NodeCounter();
+    t2.add4Sup(c2);
+
+    // inheritance traverser should reach the interface implementation precisely once
+    node.get().accept(t2);
+    Assertions.assertEquals(1, c2.getNum());
+
+  }
+
 }