Bug#458059: [NTG-pdftex] [tex-k] Bug#458059:

[Morten Høgholm <morten.hoegholm@latex-project.org>]

On Sun, 01 Jun 2008 01:55:24 +0200, Karl Berry wrote:

>     The attached file gives an error
>
> Stijn, I'm not sure if you ever found the resolution.
[...]
> You can see the loop, \makebm ends up calling itself.
>
> Evidently \makebm cannot be used in \everymath.  Even a complete
> re-archiTeXture will not help :).

The problem is this: When bm encounters a group such as happens in this  
case in the superscript, it will call \bm@mchoice defined thusly:
  \def\bm@mchoice#1#2#3#4#5{%
    \mathchoice{\hbox{#1$\displaystyle\m@th#2$}}%
               {\hbox{#1$\textstyle\m@th#3$}}%
               {\hbox{#1$\scriptstyle\m@th#4$}}%
               {\hbox{#1$\scriptscriptstyle\m@th#5$}}}

Exiting and entering mathmode like this triggers \everymath and so our  
infinite recursion is started. Easiest remedy is to also tell \everymath  
to reset itself.
  \renewcommand*\descriptionlabel[1]{%
    \hspace\labelsep
    {\everymath{\everymath{}\makebm}\normalfont\bfseries #1:}%
  }

--
Morten