[luatex] incompatible change to mathcode

[Khaled Hosny]

On Tue, May 08, 2012 at 08:11:45PM +0100, David Carlisle wrote:
> 
> Luatex has changed mathcode to allow a larger numeric range however
> changing TeX primitives without giving them new names seems suspect
> and in this particular case, since \mathcode has changed but
> \mathchardef has not the essential link between these two commands
> has been broken.
> 
> This has come to light (again) due to a latex bug report that the
> core tools latex package bm is broken in lualatex
> 
> http://www.latex-project.org/cgi-bin/ltxbugs2html?pr=tools/4188
> 
> Searching with google suggests that several other packages notably
> amsmath are similarly broken but workarounds have been provided on
> an ad hoc basis.
> 
> Can this change be reversed and TeX primitives _not_ be changed in
> incompatible ways.

We extend other primitives as well, e.g. \char (XeTeX does, too).

IMO, I think we should just extend \mathchardef in a similar way, so
that \mathchardef\matha\mathcode`a works again.

Regards,
 Khaled