Better implementation of EventCallback.Equals

[JelleHissink]

Better implementation of EventCallback.Equals

We noticed after upgrading our blazor application to .net 8.0 that some EventCallback keep being modified. Eventhough the value was the same, the same target component, the same method.

The generated code that renders the component seems to fabricate a new MulticastDelegate, having the same Type, Target and Method. The implementation of EventCallback uses Object.ReferenceEquals, so it concludes it is different every render.

Fixes #53361

[ghost]

Thanks for your PR, @JelleHissink. Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[ghost]

Hi @JelleHissink. If this is not a tell-mode PR, please make sure to follow the instructions laid out in the servicing process document.
Otherwise, please add tell-mode label.

[JelleHissink]

@dotnet-policy-service agree

[JelleHissink]

I wanted to reproduce the build error locally, however I am having issues running all tests locally because I get this error when I execute restore.cmd:

C:\Work\github\aspnetcore\eng\targets\Npm.Common.targets(46,5): error : [email protected]: The engine "node" i
s incompatible with this module. Expected version "^14 || ^16 || ^17 || ^18 || ^19". Got "20.11.0" [C:\Work\github\aspn
etcore\src\SignalR\clients\ts\common\common.npmproj]

[SteveSandersonMS]

Would it be OK to retarget this to main so it goes in .NET 9? Targeting release/8.0 is much more complicated as we need a much more definite justification for risking other behavioral changes in a patch release.

Bear in mind that the change being introduced here doesn't only affect EventCallback.Equals; it also affects rendering as it can change which set of components get detected as needing an update according to the diffing system. It doesn't just revert to .NET 7 behavior; it creates a different behavior for rendering than existed in .NET 7 or 8. I agree that the change is a desirable one in the long term, but we try to be extremely careful about introducing subtle behavioral changes in patch releases.

I know you need a solution for your own app before then, but perhaps you could work around by calling your own EventCallback comparison utility function.

[JelleHissink]

Sorry, I managed to totally get stuck in changing the target branch, I made a new PR #53395
@SteveSandersonMS Could you assign the same properties there?

[ghost]

Hi @JelleHissink. It looks like you just commented on a closed PR. The team will most probably miss it. If you'd like to bring something important up to their attention, consider filing a new issue and add enough details to build context.