This will have to be explicitly mentioned in the migration docs as this method is meant to be overridden by user forms.

that is my plan after this is all merged

If we wanted to, we could deprecated this in cake 5 and check if _execute() is declared in a derived class or not.

Is Form::_execute() the only method we want to deprecate this way or do want to do that for all the other methods as well? Meaning:

• add process() method in 5.next
• move current _execute() method contents to process() and call process() inside current _execute()
• add deprecation warning to _execute()

Any with extension point (likely to be existing on app/plugin side).
Afaik that only fits this one method, right?

At least for these methods changed in here I don't see any as well.
But there are (probably) others which just have a removed _ so we can do that for those as well.

Is Form::_execute() the only method we want to deprecate this way or do want to do that for all the other methods as well?

I can't think of any other method currently, we don't need to go about doing similar for other protected methods. It's required for this one as it's specifically meant to be overridden in app code and documented as such.

We could always do a method_exists and call the _execute() method if it exists for backwards compatibility. It would also give us a spot to trigger a deprecation.

It's already been handled for 5.next :)
#18725