Empty extern constructor fails to compile

[Grimelios]

I'm running nightly 01/10/2025. Consider project A (a console application) that depends on project B (a library). First, here's project B (the library):

using System;

namespace B
{
    static
    {
        public static void Run()
        {
            MyClass @class = new .();
        }
    }

    public class MyClass
    {
        public extern this();
    }
}

Second, here's project A (the application):

using B;
using System;

namespace A
{
    static
    {
        public static void Main()
        {
            B.Run();
        }
    }
}

namespace B
{
    public extension MyClass
    {
        public override this()
        {
        }
    }
}

As shown, project B has a class MyClass with an empty extern constructor. Project A extends MyClass to provide an implementation for that constructor, but the project fails to compile (with error LNK2019: unresolved external symbol).

Adding a parameter to the constructor results in a successful compilation:

public class MyClass
{
    // Other relevant code is updated to also account for this parameter.
    public extern this(int32 value);
}

Interestingly, adding MyClass destructors to both projects also results in a successful compilation, even with the constructor remaining empty. Adding a destructor to only one project doesn't cut it.

// In project A...
public extension MyClass
{
    public override this()
    {
    }

    public ~this()
    {
    }
}

// In project B...
public class MyClass
{
    public extern this();

    public ~this()
    {
    }
}