Program: 84879
Project: 84879
Buggy source:
@Override public IValue checkArguments(MarkerList markers,IValue instance,IArguments arguments,ITypeContext typeContext){
  int len=arguments.size();
  IType parType;
  if (instance != null && (this.modifiers & Modifiers.INFIX) == Modifiers.INFIX) {
    IParameter par=this.parameters[0];
    parType=par.getType().getConcreteType(typeContext);
    IValue instance1=instance.withType(parType);
    if (instance1 == null) {
      Marker marker=markers.create(instance.getPosition(),"String_Node_Str",par.getName());
      marker.addInfo("String_Node_Str" + parType);
      marker.addInfo("String_Node_Str" + instance.getType());
    }
 else {
      instance=instance1;
    }
    if ((this.modifiers & Modifiers.VARARGS) != 0) {
      arguments.checkVarargsValue(this.parameterCount - 2,this.parameters[this.parameterCount - 1],markers,typeContext);
      for (int i=0; i < this.parameterCount - 2; i++) {
        arguments.checkValue(i,this.parameters[i + 1],markers,typeContext);
      }
      return instance;
    }
    for (int i=0; i < this.parameterCount - 1; i++) {
      arguments.checkValue(i,this.parameters[i + 1],markers,typeContext);
    }
    return instance;
  }
 else   if (instance == null && (this.modifiers & Modifiers.PREFIX) == Modifiers.PREFIX) {
    parType=this.theClass.getType();
    instance=arguments.getFirstValue();
    IValue instance1=instance.withType(parType);
    if (instance1 == null) {
      Marker marker=markers.create(instance.getPosition(),"String_Node_Str",this.name);
      marker.addInfo("String_Node_Str" + parType);
      marker.addInfo("String_Node_Str" + instance.getType());
    }
    return null;
  }
  if ((this.modifiers & Modifiers.VARARGS) != 0) {
    len=this.parameterCount - 1;
    arguments.checkVarargsValue(len,this.parameters[len],markers,typeContext);
    for (int i=0; i < len; i++) {
      arguments.checkValue(i,this.parameters[i],markers,typeContext);
    }
    return instance;
  }
  for (int i=0; i < this.parameterCount; i++) {
    arguments.checkValue(i,this.parameters[i],markers,typeContext);
  }
  return instance;
}

Fixed version (ground truth):
@Override public IValue checkArguments(MarkerList markers,ICodePosition position,IContext context,IValue instance,IArguments arguments,ITypeContext typeContext){
  int len=arguments.size();
  IType parType;
  if (instance != null && (this.modifiers & Modifiers.INFIX) == Modifiers.INFIX) {
    IParameter par=this.parameters[0];
    parType=par.getType().getConcreteType(typeContext);
    IValue instance1=instance.withType(parType);
    if (instance1 == null) {
      Marker marker=markers.create(instance.getPosition(),"String_Node_Str",par.getName());
      marker.addInfo("String_Node_Str" + parType);
      marker.addInfo("String_Node_Str" + instance.getType());
    }
 else {
      instance=instance1;
    }
    if ((this.modifiers & Modifiers.VARARGS) != 0) {
      arguments.checkVarargsValue(this.parameterCount - 2,this.parameters[this.parameterCount - 1],markers,typeContext);
      for (int i=0; i < this.parameterCount - 2; i++) {
        arguments.checkValue(i,this.parameters[i + 1],markers,typeContext);
      }
      return instance;
    }
    for (int i=0; i < this.parameterCount - 1; i++) {
      arguments.checkValue(i,this.parameters[i + 1],markers,typeContext);
    }
    return instance;
  }
 else   if (instance == null && (this.modifiers & Modifiers.PREFIX) == Modifiers.PREFIX) {
    parType=this.theClass.getType();
    instance=arguments.getFirstValue();
    IValue instance1=instance.withType(parType);
    if (instance1 == null) {
      Marker marker=markers.create(instance.getPosition(),"String_Node_Str",this.name);
      marker.addInfo("String_Node_Str" + parType);
      marker.addInfo("String_Node_Str" + instance.getType());
    }
    return null;
  }
  if (instance != null) {
    if ((this.modifiers & Modifiers.STATIC) != 0) {
      if (instance.valueTag() != IValue.CLASS_ACCESS) {
        markers.add(position,"String_Node_Str",this.name.unqualified);
        instance=null;
      }
    }
 else     if (instance.valueTag() == IValue.CLASS_ACCESS) {
      markers.add(position,"String_Node_Str",this.name.unqualified);
    }
  }
 else   if ((this.modifiers & Modifiers.STATIC) == 0) {
    if (context.isStatic()) {
      markers.add(position,"String_Node_Str",this.name);
    }
 else {
      markers.add(position,"String_Node_Str",this.name.unqualified);
      instance=new ThisValue(position,context.getThisClass().getType());
    }
  }
  if ((this.modifiers & Modifiers.VARARGS) != 0) {
    len=this.parameterCount - 1;
    arguments.checkVarargsValue(len,this.parameters[len],markers,typeContext);
    for (int i=0; i < len; i++) {
      arguments.checkValue(i,this.parameters[i],markers,typeContext);
    }
    return instance;
  }
  for (int i=0; i < this.parameterCount; i++) {
    arguments.checkValue(i,this.parameters[i],markers,typeContext);
  }
  return instance;
}