Re: [possible patch] Remove the '\\[0pt]' string from the last line of a verse block in LaTeX export

[Ihor Radchenko <yantar92@posteo.net>]

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

>> As for {[}{]}, it is a bit difficult to implement. Especially when we
>> also consider user filters and derived backends. If we have several
>> transcoders of consequent elements, there is always a risk that even
>> when a given filter/transcoder is generating a valid LaTeX code,
>> concatenating them may still cause issues like we have with \\.
>
> I see. I think pandoc's solution is what Leslie Lamport recommends
> (naturally, Lamport doesn't say to enclose /all/ brackets in curly
> braces).

This turned out to be a lot easier than I thought.
See the attached patch.

>> \command
>> [unrelated text]
>>
>> If there are, we may actually want to consider pandoc's approach
>> seriously.
>
> In principle, any environment that takes an optional argument in a
> "dangerous" position. Just do a simple test. Something like this:
>
> #+begin_figure
> [lorem] ipsum
> #+end_figure
>
> will throw an error like ''LaTeX Error: Unknown float option...''
>
> Of course, putting an empty line after #+begin... usually solves it. But
> the user may not know it.
>
> There are also a number of commands with an optional argument. For
> example \pagebreak. Something like this will give an error:
>
> lorem @@latex:\pagebreak@@ [ipsum]
>
> \item is another typical example, but in this case org adds \relax.

With the patch, I am getting the following:

* This is test
lorem @@latex:\pagebreak@@ [ipsum]

#+begin_figure
[lorem] figure
#+end_figure

| [foo] | 2 |
| [bar] | 3 |

- [bax]
- [aur]

exports to

lorem \pagebreak {[}ipsum]

\begin{figure}
{[}lorem] figure
\end{figure}

\begin{center}
\begin{tabular}{lr}
{[}foo] & 2\\[0pt]
{[}bar] & 3\\[0pt]
\end{tabular}
\end{center}

\begin{itemize}
\item {[}bax]
\item {[}aur]
\end{itemize}


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From db3fa01d6f15b3d3f499f77e342a608a822029c8 Mon Sep 17 00:00:00 2001
Message-ID: <db3fa01d6f15b3d3f499f77e342a608a822029c8.1705583005.git.yantar92@posteo.net>
From: Ihor Radchenko <yantar92@posteo.net>
Date: Thu, 18 Jan 2024 14:01:32 +0100
Subject: [PATCH] ox-latex: Make sure that [text] is not misinterpreted as
 LaTeX argument

* lisp/ox-latex.el (org-latex-plain-text): Protect plain text starting
from [.  It might be misinterpreted as optional command argument if
previous exported fragment ends with a command accepting such.
*
testing/lisp/test-ox-latex.el (text-ox-latex/protect-square-brackets):
Add new test.

Link: https://orgmode.org/list/87o7dju9vn.fsf@posteo.net
---
 lisp/ox-latex.el              |  9 +++++++++
 testing/lisp/test-ox-latex.el | 23 +++++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/lisp/ox-latex.el b/lisp/ox-latex.el
index 432f09f4e..a3505c25f 100644
--- a/lisp/ox-latex.el
+++ b/lisp/ox-latex.el
@@ -3094,6 +3094,15 @@ (defun org-latex-plain-text (text info)
 		    "\\(?:[ \t]*\\\\\\\\\\)?[ \t]*\n"
                     (concat org-latex-line-break-safe "\n")
                     output nil t)))
+    ;; Protect [foo] at the beginning of lines / beginning of the
+    ;; plain-text object.  This prevents LaTeX from unexpectedly
+    ;; interpreting @@latex:\pagebreak@@ [foo] as a command with
+    ;; optional argument.
+    (setq output (replace-regexp-in-string
+                  (rx bol (0+ space) (group "["))
+                  "{[}"
+                  output
+                  nil nil 1))
     ;; Return value.
     output))
 
diff --git a/testing/lisp/test-ox-latex.el b/testing/lisp/test-ox-latex.el
index 41df1b823..237ad97ec 100644
--- a/testing/lisp/test-ox-latex.el
+++ b/testing/lisp/test-ox-latex.el
@@ -29,6 +29,29 @@ (unless (featurep 'ox-latex)
 
 \f
 
+(ert-deftest text-ox-latex/protect-square-brackets ()
+  "Test [foo] being interpreted as plain text even after LaTeX commands."
+  (org-test-with-exported-text
+      'latex
+      "* This is test
+lorem @@latex:\\pagebreak@@ [ipsum]
+
+#+begin_figure
+[lorem] figure
+#+end_figure
+
+| [foo] | 2 |
+| [bar] | 3 |
+
+- [bax]
+- [aur]
+"
+    (goto-char (point-min))
+    (should (search-forward "lorem \\pagebreak {[}ipsum]"))
+    (should (search-forward "{[}lorem] figure"))
+    (should (search-forward "{[}foo]"))
+    (should (search-forward "\\item {[}bax]"))))
+
 (ert-deftest test-ox-latex/verse ()
   "Test verse blocks."
   (org-test-with-exported-text
-- 
2.43.0


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-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
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