Document class gsm-l's ToC is messed up

Question

I'm writing a text using document class gsm-l but the number of the sections overlap with the section symbol §, like this:

Here's an MWE:

\documentclass[a4paper,12pt]{gsm-l}

\usepackage{amsthm, amssymb, amsmath, amsfonts}
\usepackage[utf8]{inputenc}       
\usepackage[T1]{fontenc}           
\usepackage[brazil]{babel} 
\usepackage{gfsartemisia-euler}
\usepackage{dsfont}

\begin{document}

\chapter*{foo}

\tableofcontents

\chapter{foo}

\section{foo}

\section{foo}

\chapter{foo}

\section{foo}

\section{foo}

\end{document}

I think the problem is either with \usepackage{gfsartemisia-euler} or \usepackage[T1]{fontenc}. I tried commenting each one of these packages with % separately, and when I commented the two above (again, one at a time!), the problem was fixed. I don't know why this is happening. What do I do?

Answer 1

There is a bug in the Artemisia-Euler font in the T1 encoding: the § character is assigned zero width. When the OT1 encoding is used, the glyph has the correct width.

A fix for using the T1 encoding which is necessary when typesetting in Portuguese, otherwise hyphenation will be hindered up to being almost impossible, is as follows, instructing LaTeX to fetch the glyph from the OT1 encoded font:

\documentclass[a4paper,12pt]{gsm-l}

\usepackage[T1]{fontenc}           
\usepackage[utf8]{inputenc}       
\usepackage[brazil]{babel} 
\usepackage{amsthm, amssymb, amsmath, amsfonts}

\usepackage{gfsartemisia-euler}
\usepackage{dsfont}

% fix the width of the § glyph
\UndeclareTextCommand{\textsection}{T1}
\DeclareTextSymbolDefault{\textsection}{OT1}

\begin{document}

\tableofcontents

\chapter{foo}

\S1

\section{foo}

\section{foo}

\chapter{foo}

\section{foo}

\section{foo}

\end{document}

Note

The gsm-l class has nothing to do with the issue, except for the fact it shows it, since it uses the § glyph in the table of contents.

Here's a really minimal example:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{gfsartemisia-euler}

\begin{document}

{\fontencoding{OT1}\selectfont\S1}

{\fontencoding{T1}\selectfont\S1}

\end{document}

From the output it's clear that § has zero width in the T1 encoded font. The proposed workaround has no consequences on hyphenation, because § doesn't participate to it anyway.

I checked all Artemisia-Euler fonts in the T1 encoding and all have § with zero width. This is bad and good news together: it's bad because it's a bug; it's good because the proposed hack will work independently of the current font.

Answer 2

Apparently there's a fontencoding clash between T1 and OT1 occuring. The wrong spacings etc. vanish if OT1 is used instead of T1:

\documentclass[a4paper,12pt]{gsm-l}

\usepackage{amsthm, amssymb, amsmath, amsfonts}
\usepackage[utf8]{inputenc}       
\usepackage[OT1]{fontenc}           
\usepackage[brazil]{babel} 
\usepackage{gfsartemisia-euler}
\usepackage{dsfont}

\begin{document}

\chapter*{foo}

\tableofcontents

\chapter{foo}

\section{foo}

\section{foo}

\chapter{foo}

\section{foo}

\section{foo}

\end{document}