EventCallback not working for generic components

[stsrki]

This issue is continuation of #8385

The original problem is fixed but now the problem is that generic typeparam must always be defined when using custom component. It seems that Blazor is not recognizing it implicitly.

The minimal sample can be found here: https://github.com/stsrki/BlazorGenericEventIssue

Not working:

This will giving me error because TValue is not defined:

<SelectEdit Value="@someValue" ValueChanged="@((v) => someValue=v)">

Error CS0029 Cannot implicitly convert type 'Microsoft.AspNetCore.Components.UIWheelEventArgs' to 'int'
Error CS1662 Cannot convert lambda expression to intended delegate type because some of the return types in the block are not implicitly convertible to the delegate return type
Error CS0029 Cannot implicitly convert type 'int' to 'System.Threading.Tasks.Task'
Error CS0266 Cannot implicitly convert type 'object' to 'int'. An explicit conversion exists (are you missing a cast?)

Working:

This is working only after TValue is set. It is not recognized from the context.

<SelectEdit TValue="int" Value="@someValue"ValueChanged="@((v) => someValue=v)">

Expected behavior:

TValue should be automatically detected from the supplied value(s).

[marin-bratanov]

May be related/duplicate of #12226

[pranavkm]

As @marin-bratanov this is pretty similar to #12226. We'll use the other issue to track further work.