using System;

using System.ComponentModel.DataAnnotations;

using System.Linq.Expressions;

using System.Reflection;

​

class TestClass {

    //[Display(Name = "Test")]

    public int TestProperty { get; set; }

}

​

static class Extensions<T> {

    public static string Label<TType>(Expression<Func<T, TType>> prop) {

        var propertyInfo = ((MemberExpression) prop.Body).Member as PropertyInfo;

        if (propertyInfo is not PropertyInfo) {

            throw new Exception();

        }

        DisplayAttribute attr = propertyInfo.GetCustomAttribute<DisplayAttribute>();

        if (attr is DisplayAttribute) {

            return attr.Name;

        }

        return propertyInfo.Name;

    }

}

​

public class Program {

    public static void Main(string [] args) {

        var label = Extensions<TestClass>.Label(mt => mt.TestProperty);

        Console.WriteLine($"Property display attribute is {label}");

    }

}