bug#65267: 30.0.50; modifying debug-ignored-errors during startup with --debug-init is broken

[Štěpán Němec]

On Sun, 13 Aug 2023 12:19:31 -0400
Stefan Monnier via wrote:

> Yeah, it's wrong, but I'm not sure how to fix it:
> `--debug-init` needs to change the value of `debug-ignored-errors` while
> `init.el` is executed,

FWIW, I'm sure I'm missing something, but the above is far from obvious
to me.  Why does --debug-init need to muck with debug-ignored-errors at
all?  debug-ignored-errors usually/mostly contains errors unlikely to
occur during startup, and even if they do occur during startup, why
should Emacs not respect debug-ignored-errors and ignore them?  (I also
couldn't find this exception (i.e., --debug-init causing
debug-ignored-errors to be ignored) documented anywhere, BTW.)

> but it's not clear how to "revert" to "the value
> it would have if we had not changed it" once we're finished processing
> `init.el`.
>
> Maybe we should introduce a new `inhibit-debug-ignored-errors` which we
> could let-bind while loading `init.el` without having to modify
> `debug-ignored-errors` itself?

If ignoring debug-ignored-errors during startup is really necessary,
that sounds like a possibly cleaner way, indeed (albeit introducing
yet another form to ignore another form ignoring errors...).

On Sun, 13 Aug 2023 19:32:46 +0300
Eli Zaretskii wrote:

> We could document that modifying debug-ignored-errors only works
> reliably if done from after-init-hook.  WDYT?

Pushing the breakage downstream... would mean packages like yasnippet
would have to adapt, among other things.  Not the end of the world, I
guess, but I still don't understand why the breakage (or "change in
behavior", if you prefer) is necessary or desired.

-- 
Štěpán