C# 9 Records not providing an override of == when running on .Net Core 3

[epNickColeman]

Version Used: .Net 3.1.403 C# 9.0

Steps to Reproduce:

1. Create two equivalent records
2. Compare with .equals, observe true
3. Compare with ==, observe false

        [Test]
        public void RecordsAreEqualByValue()
        {
            var zaphod1 = new Person(firstName: "Zaphod", lastName: "Beeblebrox");
            var zaphod2 = new Person(firstName: "Zaphod", lastName: "Beeblebrox");

            zaphod1.Should().Be(zaphod2); // Passes
            (zaphod1 == zaphod2).Should().BeTrue(); // Fails in .net core 3, passes in .net 5
        }

Expected Behavior: I expect == to be overridden regardless of framework version Actual Behavior: == is not overridden in .net core3

[Youssef1313]

The following prints true for me in .NET Core 3.

using System;

namespace System.Runtime.CompilerServices
{
    class IsExternalInit { }
}

namespace ConsoleApp3
{
    record Person(string A, string B);

    class Program
    {
        static void Main(string[] args)
        {
            var a = new Person("a", "b");
            var b = new Person("a", "b");
            Console.WriteLine(a == b);
        }
    }
}

[epNickColeman]

Ah, I see it works when targeting 3.1, but using the .net 5.0.300 SDK. I had the following global.json

{
  "sdk": {
    "version": "3.1.300",
    "rollForward": "latestFeature"
  }
}

which means it was built with 3.1.403 version of the compiler - so I guess this is we can use the 5.0 SDK to target 3.1 while still necessary, so this can probably be closed. Thanks for taking the time to look at this.

[huoyaoyuan]

C# 9 was shipped with .NET 5. Are you sure you can compile C# 9 with 3.1 SDK?