bug#63564: 29.0.91; (setcdr) behaves differently between natively and byte compiled code

[Mattias Engdegård]

> Users have discovered there's a markdown-mode function that behaves
> differently depending Emacs is executing byte-compiled code or natively
> compiled code.
> 
> The issue is documented
> [here](https://github.com/jrblevin/markdown-mode/issues/578).

> 
> There are two examples in the issue that will produce an `Wrong type
> argument: consp, nil` error on the natively compiled version of
> `markdown-imenu-create-nested-index`, but not the byte-compiled or
> interpreted version.  A user has provided a disassembly of the natively
> compiled code for that function.
> 
> The last user has said and I can confirm the offending line seems to be 
> `(setcdr
> sibling-alist alist)` in that function.
> 
> Much appreciate it if Andrea could take a look.


I'm not Andrea, but it appears that a related coding error was fixed in a 
recent commit to markdown-mode, 44f0e89534. Did that help?