“improper alphabetic constant” with hyperref and bidi packages

Question

I'm getting an "improper alphabetic constant" error in xelatex which appears to be due to an interaction between the bidi and hyperref packages, when I redefine the \section cmd. Here's an MWE:

\documentclass{report}
\usepackage[unicode]{hyperref}
\usepackage{bidi} %Must be loaded after hyperref pkg
\makeatletter
\renewcommand\section{\@startsection{section}{1}{0pt}{0pt}{0pt}{}}
\makeatother
\begin{document}
\section{\RL{foo}}
\RL{bar}
\end{document}

It's important that the text \RL{bar} be the first non-whitespace after the \section{}, otherwise the error is not triggered.

I've checked the suggested "Similar Questions," and don't see anything quite like this.

Suggestions?

Answer 1

I do not think, you need to pass unicode option to hyperref package with XeTeX engine. So with the following example:

\documentclass{report}
\usepackage{hyperref}
\usepackage{bidi} %Must be loaded after hyperref pkg
\makeatletter
\renewcommand\section{\@startsection{section}{1}{0pt}{0pt}{0pt}{}}
\makeatother
\begin{document}
\section{\RL{foo}}
\RL{bar}
\end{document}

I get no error (using Updated TeXLive 2012) but one related warning which is due to the use of \RL macro inside \section:

Package hyperref Warning: Token not allowed in a PDF string (Unicode):
(hyperref)                removing `\RL' on input line 9.

For details see page 19 of hyperref manual, under Replacement macros subsubsection.

To get rid off this warning, you can change your example into:

\documentclass{report}
\usepackage{hyperref}
\usepackage{bidi} %Must be loaded after hyperref pkg
\makeatletter
\renewcommand\section{\@startsection{section}{1}{0pt}{0pt}{0pt}{}}
\makeatother
\begin{document}
\section{\texorpdfstring{\RL{foo}}{foo}}
\RL{bar}
\end{document}

and if you do not like \texorpdfstring, you can try:

\documentclass{report}
\usepackage{hyperref}
\usepackage{bidi} %Must be loaded after hyperref pkg
\makeatletter
\renewcommand\section{\@startsection{section}{1}{0pt}{0pt}{0pt}{}}
\pdfstringdefDisableCommands{%
\let\RL\@firstofone
}
\makeatother
\begin{document}
\section{\RL{foo}}
\RL{bar}
\end{document}