Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> I also wanted to ask whether to extend that approach to the other advice
>> installed in `elisp--local-variables´
>
> That would be nice, but...
>
>> but then noticed that `macroexpand´ is actually a built-in.
>
> `elisp--local-variables´ doesn't use that built-in any more, it uses
> `macroexpand-1` instead, which is implemented in `macroexp.el` :-)
>
> But the problem is that the advice wraps the call within
> a `condition-case` and that's inconvenient to do in a way which
> doesn't interfere too much with "normal use" (e.g. doesn't hide/catch
> errors when we don't want to, and doesn't impose too much of
> a performance cost either).

Agreed.

Anyway, here are two patches: One for Emacs 29 and one for master.

The patch for Emacs 29:

- does not contain the rather non-local change for avoiding compiler
  macros.  But it fixes this bug, anyway, by just ignoring all errors
  during the `macroexpand-all' call.

- contains a "don't merge to master" maker in the commit message.

What do you think?