Kebab case event listeners broken

[cathrinevaage]

Version

3.0.2

Reproduction link

https://codesandbox.io/s/eloquent-cdn-yipvt?file=/src/App.vue

Steps to reproduce

Attach an event listener on a component using kebab-casing.

<SomeComponent @some-event="someListener" />

In the component, emit an event using with any camel, Pascal, or kebab casing ('some-event', SomeEvent, someEvent).

What is expected?

The event listener should be called.

What is actually happening?

The event listener is not called.

---

This is a duplicate of #2429, but closed issues seem to get little attention, so I'm creating a new one with working reproductions and some insight.

As of #2278, listeners added with camel casing broke.
In that pr, all events, both listener names, and emitted event names, were converted to camelCase.

@some-event="someListener" is compiled to the vnode prop onSomeEvent: _ctx.someListener, as can be observed in the template explorer.

However, this can not be observed in the compiled template in the app. The render function for App.vue is printed in the console in the reproduction. Here you can see that it's compiled the same way as it was in v3.0.0; "onSome-event": _ctx.someListener.
When the emitted event is converted to camelCase, the handler can't be found.

I believe this is the cause of the issue.

[cathrinevaage]

This is not reproducible when creating a fresh new project with e.g vite.
Even though, in codesandbox, the compiler is clamped to ^3.0.1, the wrong behaviour persists. I suspect this is an issue at their end instead.
Closing.