[RDG] Route handlers with the same parameters but differing nullability produce compiler warnings

[captainsafia]

At the moment, it's hard to use our strongly-typed overloads strategy to generate code that correctly handles two route handlers with the same parameters but differing nullability:

app.MapPost("/foo", (Todo todo) => ...);
app.MapPost("/bar", (Todo? todo) => ...);

We might consider generating two different strongly-typed overloads, one with the nullability annotations and one without:

MapPost(System.Action<Todo>);
MapPost(System.Action<Todo?>);

But overload resolution is not able to discern between the two delegate signatures and treats them as ambiguous overloads.

We can also emit only the overload that expects an NRT:

MapPost(System.Action<Todo?>);

But that presents a nullability warning to users (CS8622) when passing an overload to the delegate that does not expect an NRT.

[captainsafia]

Update: this only impacts scenarios where the handler is passed as an inline lambda.

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 8 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.

[captainsafia]

Closed via interceptors support.