Re: error message at line break

[Nicolas Goaziou]

Hello,

Étienne Deparis <address@hidden> writes:

>   Debugger entered--Lisp error: (wrong-type-argument char-or-string-p nil)
>   insert-before-markers-and-inherit(nil)
>   org-comment-line-break-function(t)

[...]

> I confirm that I've the same variable set in my Emacs config file:
>
>   (setq-default auto-fill-function 'do-auto-fill)
>
> Which I take from the Emacs Wiki AutoFill page¹, with the explanation
> of: « If you would like to enable auto fill for all major modes, you can
> add this single line to your configuration ».
>
> ¹ https://www.emacswiki.org/emacs/AutoFillMode

This is a very bad (outdated ?) advice! With this, you force
`do-auto-fill' function in every major mode, even if that function
doesn't have a clue about what the major mode is about. Also this
prevents the major mode from setting its own filling. Do you have any
reason to do this?

A correct way to activate auto fill in all text-based modes (including
Org), is, for example,

  (add-hook 'text-mode-hook (lambda () (auto-fill-mode 1)))

See (info "(emacs)Auto Fill") for more information.

> To fix this, I simply replace the last line of
> `org-comment-line-break-function' (in ./lisp/org.el, line 19723) from:
>
>   (insert-before-markers-and-inherit fill-prefix)
>
> To
>
>   (when fill-prefix
>     (insert-before-markers-and-inherit fill-prefix))

Well, the fix is cheap, sure, but, OTOH, the error is to be expected,
since you force Org to use a function which is not adequate.

I'm not sure we should paper over this kind of misuse of
`auto-fill-function'.

WDYT?

Regards,

-- 
Nicolas Goaziou