Math comma issue with babel and MinionPro/MinionMath: typeset as an inverted E

Question

The following code typesets an inverted E instead of the math comma on my system (texlive 2014, OSX)

\documentclass{book} 

\usepackage[T1]{fontenc}
\usepackage[onlytext]{MinionPro}
\usepackage{minionmath}
\usepackage[italian,british]{babel} 

\begin{document}     
Hallo. $(a,b)$. $(c, d)$.    
\end{document}

All the mentioned commands seem necessary; without "italian", there is no problem; there is also no problem if "minionmath" is taken out. (The "british" can be taken out, though, and the problem still remains.) Can anybody help here?

P.S. It seems that adding \usepackage{icomma} after the babel command "sort of" solves the problem; but then I would have to go through thousands of commas in my files and check whether there is a space after them. That is not feasible...

Answer 1

There is wrong code in italian.ldf: such code is wrong because it relies on the mathcode of the comma being the same as in the standard setting, which is not the case when minionmath is used. Indeed the standard math code for the comma is "613B, which becomes "622C with minionmath.

The consequence is that \virgola and \virgoladecimale point to a random character.

You should be able to fix the problem with a hack: define \virgola to point to the correct mathchar (after loading minionmath) and \virgoladecimale to be the same character, but made into an Ordinary atom with braces.

\documentclass{book} 

\usepackage[T1]{fontenc}
\usepackage[italian,british]{babel} 

\usepackage[onlytext]{MinionPro}
\usepackage{minionmath}

\mathchardef\virgola=\mathcode`,
\def\virgoladecimale{{\virgola}}

\begin{document}     
Hallo. $(a,b)$. $(c, d)$.    
\end{document}