RTL (Right-To-Left) latex environment not defined for xelatex

[daamien]

Hi !

Thanks for this amazing software !

I am trying to build a document writtent in a Right-To-Left language

Here's a minimal example:

<div dir="rtl" markdown="1"> 
ﭗﯿﺸﮕﻔﺗﺍﺭ                                                                                                
</div>   

When I try to generate the PDF with this command

pandoc --pdf-engine=xelatex sample.md -o sample.pdf

I get this error

Error producing PDF.                                                                                                                                      
! LaTeX Error: Environment RTL undefined.                                                                                                                 
                                                                                                                                                          
See the LaTeX manual or LaTeX Companion for explanation.                                                                                                  
Type  H <return>  for immediate help.                                                                                                                     
 ...                                                                                                                                                      
                                                                                                                                                          
l.62 \begin{RTL}                                                                                                                                                            

Looking at the default template, I can see that the RTL env is only defined for pdftex

https://github.com/jgm/pandoc-templates/blob/master/default.latex#L354

Is there's a specific reason for that ?

Would it be possible to this env for xelatex too ?

[jgm]

I believe the RTL environment is provided by the bidi package.
My vague recollection is that those definitions were added for pdflatex because it didn't use bidi?
Something may have changed regarding this when we switched from using polyglossia to using babel.
@mb21 @adunning can you see what is going on here and how it should be fixed?

[jgm]

You could try adding \usepackage{bidi} to your preamble to see if that helps.

[daamien]

Yes ! Adding bidi in the header solves the problem.

Sorry I am not familiar with that topic, but at first glance I'd say that when dir = rtl and --pdf-engine=xelatex are defined, then the bidi package should loaded by the template...

[jgm]

Sorry I am not familiar with that topic, but at first glance I'd say that when dir = rtl and --pdf-engine=xelatex are defined, then the bidi package should loaded by the template...

Yes, I think that's probably right -- and probably it wasn't needed before, because polyglossia loaded it automatically. But let me see if anyone can confirm that.

[jgm]

See https://tex.stackexchange.com/questions/392175/how-can-i-defer-the-loading-of-the-bidi-package for some hints on loading order for bidi. This also confirms that bidi is loaded by polyglossia, which is probably why we originally loaded it only for pdflatex.

[daamien]

Sure, The workaround is easy and there's no hurry...

Thanks again for your time and efforts

[tarleb]

Somewhat related: #8283.

[jgm]

I tried the following patch to the latex template:

diff --git a/data/templates/default.latex b/data/templates/default.latex
index bb752a680..e9c69537b 100644
--- a/data/templates/default.latex
+++ b/data/templates/default.latex
@@ -357,15 +357,6 @@ $endfor$
 \ifLuaTeX
   \usepackage{selnolig}  % disable illegal ligatures
 \fi
-$if(dir)$
-\ifPDFTeX
-  \TeXXeTstate=1
-  \newcommand{\RL}[1]{\beginR #1\endR}
-  \newcommand{\LR}[1]{\beginL #1\endL}
-  \newenvironment{RTL}{\beginR}{\endR}
-  \newenvironment{LTR}{\beginL}{\endL}
-\fi
-$endif$
 $if(natbib)$
 \usepackage[$natbiboptions$]{natbib}
 \bibliographystyle{$if(biblio-style)$$biblio-style$$else$plainnat$endif$}
@@ -392,6 +383,17 @@ $endif$
 $if(verbatim-in-note)$
 \VerbatimFootnotes % allow verbatim text in footnotes
 $endif$
+$if(dir)$
+\ifPDFTeX
+  \TeXXeTstate=1
+  \newcommand{\RL}[1]{\beginR #1\endR}
+  \newcommand{\LR}[1]{\beginL #1\endL}
+  \newenvironment{RTL}{\beginR}{\endR}
+  \newenvironment{LTR}{\beginL}{\endL}
+\else
+  \usepackage{bidi}
+\fi
+$endif$
 \hypersetup{
 $if(title-meta)$
   pdftitle={$title-meta$},

But this did not work. Tried with

::: {dir=rtl}
hello
:::

With --pdf-engine=pdflatex I get 'olleh' at the left margin. With --pdf-engine=xelatex I get 'hello' at the right margin. With --pdf-engine=lualatex I get

Error producing PDF.
! Emergency stop.
<read *> 
   
l.91 \RequireXeTeX

So this isn't the solution.

[jgm]

If we can't find a solution, we may need to document that dir=rtl won't work with xelatex and lualatex. But hopefully there's a better way!

[tarleb]

I got decent result with --pdf-engine=lualatex when using the luabidi package. Still trying to get xelatex to work, no success so far.