foo1.cs

      foreach (var referenceExpression in codeBody.ThisAndDescendants<IReferenceExpression>())
      {
        var resolveResult = referenceExpression.Reference.Resolve();
        if (!resolveResult.ResolveErrorType.IsAcceptable) continue;

        var declaredElement = resolveResult.Result.DeclaredElement;

        var field = declaredElement as IField;
        if (field != null)
        {
          if (!field.IsReadonly && !field.IsConstant)
            consumer.AddHighlighting(new NonReadonlyMemberInGetHashCodeWarning(referenceExpression, field));
        }

        var property = declaredElement as IProperty;
        if (property != null)
        {
          if (property.IsAuto && property.Setter != null && referenceExpression.IsCSharp6Supported())
            consumer.AddHighlighting(new NonReadonlyMemberInGetHashCodeWarning(referenceExpression, property));
        }

        var method = declaredElement as IMethod;
        if (method.IsObjectGetHashCodeMethod() && referenceExpression.QualifierExpression.GetOperandThroughParenthesis() is IBaseExpression)
        {
          consumer.AddHighlighting(new BaseObjectGetHashCodeCallInGetHashCodeWarning(referenceExpression));
        }
      }

foo2.cs

      foreach (var referenceExpression in codeBody.ThisAndDescendants<IReferenceExpression>())
      {
        var resolveResult = referenceExpression.Reference.Resolve();
        if (!resolveResult.ResolveErrorType.IsAcceptable) continue;

        switch (resolveResult.Result.DeclaredElement)
        {
          case IField field when !field.IsReadonly && !field.IsConstant:
            consumer.AddHighlighting(new NonReadonlyMemberInGetHashCodeWarning(referenceExpression, field));
            break;

          case IProperty property when property.IsAuto
                                    && property.Setter != null
                                    && referenceExpression.IsCSharp6Supported():
            consumer.AddHighlighting(new NonReadonlyMemberInGetHashCodeWarning(referenceExpression, property));
            break;
            
          case IMethod method when method.IsObjectGetHashCodeMethod()
                                && referenceExpression.QualifierExpression.GetOperandThroughParenthesis() is IBaseExpression:
            consumer.AddHighlighting(new BaseObjectGetHashCodeCallInGetHashCodeWarning(referenceExpression));
            break;
        }
      }