Conflict between arydshln and tabu and X column type?

Question

\documentclass{article}
\usepackage{tabu}
\usepackage{arydshln}

\begin{document}
\begin{table}
\begin{tabu}{l X}
a & b
\end{tabu}
\end{table}
\end{document}

This gives me the following two error messages over and over:

! Missing \cr inserted.
<inserted text> 
                \cr 
l.10 \end{tabu}

I'm guessing that you meant to end an alignment here.

! Misplaced \cr.
<inserted text> \cr 

l.10 \end{tabu}

I can't figure out why you would want to use a tab mark
or \cr or \span just now. If something like a right brace
up above has ended a previous alignment prematurely,
you're probably due for more error messages, and you
might try typing `S' now just to see what is salvageable.

If I do one of the following, the error disappears:

• Change the X column to l
• Remove \usepackage{arydhsln}

However, I have a big document that uses a lot of tabu X columns in some sections, and I need arydshln for the \hdashline command when drawing complex (not in the sqrt(-1) sense) mathematical matrices in other places.

Can this conflict be resolved? How?

Answer 1

You have to swap the loading order as tabu modifies some internals arydshln uses (as noted in section 9 of the documentation).

\documentclass{article}
\usepackage{arydshln}
\usepackage{tabu}

\begin{document}
\begin{table}
\begin{tabu}{l X}
a & b
\end{tabu}
\end{table}
\end{document}