Re: [bug] `org-latex-line-break-safe' breaks the export of verse blocks to LaTeX

[Ihor Radchenko <yantar92@posteo.net>]

Juan Manuel Macías <maciaschain@posteo.net> writes:

> The recent addition of the `org-latex-line-break-safe' constant makes it
> impossible to compile verse blocks. The reason is that now a \\ is
> inserted between each stanza (aka each paragraph), instead of the
> `\vspace{1em}' as before. That's wrong, as this compile error message
> says:

Thanks for reporting!
Fixed on main.
https://git.savannah.gnu.org/cgit/emacs/org-mode.git/commit/?id=5fa66c7ffc4efbea11357fe0d05bc570855cfa91

This was an omission when replacing "\\" instances with safer version in
ox-latex.el.

> On the other hand, I have a few reservations about the usefulness of
> org-latex-line-break-safe. To begin with, it is a particular solution
> applied in a general way. This can have unexpected consequences, as has
> happened in verse blocks. It's like putting your whole body in a
> cast because of a broken finger.

The idea is to use "\\\someescapeLaTeXcommand" rather than "\\". The
latter can take arguments unexpectedly. See
https://orgmode.org/list/8735c0kpb9.fsf@localhost

> I think if the reason for this addition is to prevent problems with
> square brackets, in certain contexts, why not just apply a point
> solution? For example, putting {[}, which is a common LaTeX way to
> protect a square bracket.

Because people export tables not only to LaTeX, but also to other
formats. {[} makes no sense then.

> Use a macro, for example, or even
> define a new entity, something like:
>
> (setq org-entities-user
>       '(("lbrack" "{[}" nil "[" "[" "[" "[")
> 	("rbrack" "{]}" nil "]" "]" "]" "]")))

It will be unclear when to use such entity. Note that it is not obvious
at all that LaTeX export specifically will stumble on

| [1, 2] |
| [3, 4] |

without knowing LaTeX internals and checking the exported LaTeX
intermediate source closely.

We already ask users to deal with Org parser oddities. If we also demand
knowing LaTeX oddities, it will be too much. Better modify parser to
export valid Org syntax into valid LaTeX.

> And finally, I think that applying a general solution to this problem is
> something that should be done(IMHO) in LaTeX and not in Org, for
> example, with some new package that would protect certain signs or
> through ad hoc LaTeX/Lua code.

Either way, we will need to use the new package in ox-latex.el. And our
current approach is somewhat better because users can still use direct
LaTeX @@latex:\\@@ if they want to get "\\" exactly.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>