Edit and Continue for members of generic types

[jnm2]

Modifying or adding a method in a generic type is not currently supported: https://github.com/dotnet/roslyn/blob/main/docs/wiki/EnC-Supported-Edits.md#not-supported-edits This seems like a big-ticket item, but please consider implementing it.

It comes up a lot for me. Right now, for example, I'm debugging an application and want to try eight permutations in a generic class's constructor. Building and setting up the scenario eight times is not as fun as EnC would be.

(Opened from dotnet/roslyn#29667 to track runtime work per @tmat's request.)

[danroth27]

Related Visual Studio feedback issue: https://developercommunity.visualstudio.com/t/Blazor-Hot-Reload-is-not-working-compon/10247440

[danroth27]

@mikelle-rogers

[AaronRobinsonMSFT]

@jnm2 Is the following transform representative of your desired scenario? We're trying to understand the cost/scope of possible improvements and we want to make sure we understand the specific ask here.

// Before
class Foo<T>
{
    public Foo(T a)
    {
        Console.WriteLine("Unknown");
    }
}
public class Program
{
    public static void Main()
    {
        var s = new Foo<string>("1");
        var i = new Foo<int>(2);
        Console.WriteLine(3);
    }
}

// After
class Foo<T>
{
    public Foo(T a)
    {
        if (typeof(T) == typeof(int))
        {
            Console.WriteLine(a);
        }
        else if (typeof(T) == typeof(string))
        {
            Console.WriteLine(a);
        }
        else
        {
            Console.WriteLine("Unknown");
        }
    }
}
public class Program
{
    public static void Main()
    {
        var s = new Foo<string>("1");
        var i = new Foo<int>(2);
        Console.WriteLine(3);
    }
}

[jnm2]

@AaronRobinsonMSFT Yes, that could be representative. In the cases I remember, I didn't reference typeof(T) in the edits, but theoretically that could happen I suppose.

[AaronRobinsonMSFT]

Completed with #85269