[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.

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.
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[captainsafia]

Closed via interceptors support.