Hi,

AUCTeX has taken back this change, realizing that texmathp.el is also used in contexts where the mechanisms of AUCTeX to find out about LaTeX packages being used does not work. I do think this is already fixed in the latest AUCTeX version. At least it is fixed in their git.

- Carsten

Carsten

On Fri, Aug 28, 2020 at 7:09 AM Kyle Meyer <kyle@kyleam.com> wrote:

Stefi writes:

> It might be a change to texmathp.el. It is part of Auctex and checks if
> math mode is on or off. I could not find align environment in the list
> of default environments. Maybe that has changed.
>
> However, I added align and align* to "Texmathp Tex Commands" from the
> customize browser (open a .tex file to customize auctex). Tab-expansion
> is working now. Can anyone confirm?
>
> In my .emacs, it added to custom-set-variables:
> '(texmathp-tex-commands (quote (("align*" env-on) ("align" env-on))))

Yes, that results in expansion on my end as well.

It looks like this issue was introduced with AUCTeX's 91701704 (Delete
overhead in extending font lock range of math expression, 2020-06-11).
If you're getting AUCTeX from ELPA, the regression is included the
current version there (12.2.4, 2020-06-29).

At the start of this month, it was fixed in f04a508f (Restore all math
environments in texmathp.el, 2020-08-01), so the issue should go away
with the next update that lands on ELPA.