Escaped percent signs in LaTeX (\%) still are considered comments in certain contexts

[isaisabel]

In LaTeX, the symbol % is considered the start of a comment. However, when escaped (%) it is considered by the latex compiler to just be a normal % character. Pandoc does not always catch these escaped comment markers correctly, interpreting them as comments in certain contexts.

See the following example:

$ pandoc --version
pandoc 1.19.2.1
Compiled with pandoc-types 1.17.0.4, texmath 0.9, skylighting 0.1.1.4
Default user data directory: /Users/jtrahan/.pandoc
Copyright (C) 2006-2016 John MacFarlane
Web:  http://pandoc.org
This is free software; see the source for copying conditions.
There is no warranty, not even for merchantability or fitness
for a particular purpose.

The example1 latex input file:

$ cat example1.tex
\documentclass{article}
\newcommand{\fakeitemize}[1]{
    \begin{itemize}
        #1
    \end{itemize}
}
\newcommand{\testcmd}[1]{
    #1
}
\begin{document}
    \fakeitemize{
        \item Pandoc is 100\% awesome.
    }

    \begin{itemize}
        \item Pandoc is 200\% awesome.
    \end{itemize}

    \testcmd{
        Pandoc is 300\% awesome.
    }
\end{document}

The output from the first conversion through pandoc. As you can see, the text starting at the escaped percent sign is lost for all text that is passed through arguments into the custom commands:

$ cat example1.tex | pandoc -f latex -t html
<ul>
<li><p>Pandoc is 100 </p></li>
</ul>
<ul>
<li><p>Pandoc is 200% awesome.</p></li>
</ul>
<p>Pandoc is 300 </p>

[jgm]

This is going to be fixed by the big rewrite of the LaTeX reader that I'm working on now.