bug#67008: 30.0.50; Multiple major mode parents

[Mattias Engdegård]

11 nov. 2023 kl. 21.13 skrev Stefan Monnier <monnier@iro.umontreal.ca>:

> Having read a bit further, I'm now not sure that `merge-ordered-lists`
> implements C3.  I suspect it provides a useful primitive with which to
> implement C3 but whether it gives the same result as C3 or not depends
> on how we call it.

Yes, the output seems very sensitive about the input order:

 (B A) (C A) (D B) (E D C) -> (E D B C A)

 (E D C) (B A) (C A) (D B) -> (E D C B A)

Maybe that's obvious for someone who knows how to use it.

It could probably be used as a general-purpose topo-sorter but it's not a very 
efficient one (at least quadratic, possibly cubic).

Oh, and the function probably shouldn't call delq on its input argument.