Blazor inline `RenderFragment` syntax does not handle `EventCallback`s Properly

[davidmilligan]

Describe the bug

Trying to use EventCallback in an "inline" razor RenderFragment results in a compilation failure. I think this is due to the generated razor cs code calling the wrong AddAttribute override on the builder.

To Reproduce

public class C : ComponentBase
{
    [Parameter] public EventCallback E { get; set; }
}

@code{
    private RenderFragment M() {
       return @<C E=@(() => { }) />;
    }
}

Expected Behavior

Compiles successfully

Actual Behavior

error CS1503: Argument 2: cannot convert from 'bool' to 'Microsoft.AspNetCore.Components.EventCallback'

Further technical details

• ASP.NET Core version: 5.0.104

Use Case:

Using bUnit to write test cases in .razor files. See: https://bunit.dev/docs/getting-started/writing-tests.html?tabs=xunit#secret-sauce-of-razor-files-tests

This issue was reported in down in the middle of an unrelated thread, but I think it was overlooked, as it wasn't really the main issue: #19640 (comment)

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[mkArtakMSFT]

@javiercn should this be transferred to the razor repo or do we have work to do here on our end?

Thanks for contacting us.

We're moving this issue to the .NET 9 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[vgallegob]

I really need this, the only way left is using the builder manually which I do not want to maintain.