bug#67008: 30.0.50; Multiple major mode parents

[Dmitry Gutov]

On 09/11/2023 07:38, Stefan Monnier via Bug reports for GNU Emacs, the 
Swiss army knife of text editors wrote:
> While it seems difficult to add support for multiple inheritance to
> `define-derived-mode`, it's fairly easy to allow a major mode to declare
> itself the spiritual heir of various other major modes beside the one
> from which it actually inherits.

I think it would help with certain customizations which check whether a 
mode is derived from e.g. js-mode.

But whatever code that runs in parent-mode-hook won't run in the 
"derived modes" that use the new mechanism, would it?

I wonder which of these two problems have a bigger impact for the 
seamless migration to ts modes.