public class LambdaEqualityComparer<T> : IEqualityComparer<T>
    {
        private readonly Func<T, T, bool> _equalsDelegate;

        public LambdaEqualityComparer(Func<T, T, bool> equalsDelegate)
        {
            _equalsDelegate = equalsDelegate;
        }

        public bool Equals(T x, T y)
        {
            Console.WriteLine($"Equals({x}, {y})");
            return _equalsDelegate(x, y);
        }

        public int GetHashCode(T obj)
        {
            return 0;
        }

        public static implicit operator LambdaEqualityComparer<T>(Func<T, T, bool> equalsDelegate)
        {
            return new LambdaEqualityComparer<T>(equalsDelegate);
        }
    }

    public class Test
    {
        public int X { get; set; }

        public int Y { get; set; }

        public override string ToString() => $"Test{{X: {X}, Y: {Y}}}";
    }

        private static void Main(string[] args)
        {
            var tests1 = Enumerable.Range(1, 3).Select(it => new Test {X = it, Y = 1});

            var r = tests1.Distinct((LambdaEqualityComparer<Test>)((x, y) =>  x.Y == y.Y)).ToArray();

            Console.WriteLine("结果===================");
            foreach(var t in r)
            {
                Console.WriteLine(t);
            }
        }

Equals(Test{X: 1, Y: 1}, Test{X: 2, Y: 1})
Equals(Test{X: 1, Y: 1}, Test{X: 3, Y: 1})
结果===================
Test{X: 1, Y: 1}

        public int GetHashCode(T obj)
        {
            return obj.GetHashCode();
        }

结果===================
Test{X: 1, Y: 1}
Test{X: 2, Y: 1}
Test{X: 3, Y: 1}