Re: [Bug-AUCTeX] 11.86: tex-preview's showlabels option doesn't work with amsmath's multline environment; workaround found

[Ralf Angeli]

* address@hidden (2010-10-30) writes:

> It is a known problem that latex-preview's showlabels option doesn't
> work with amsmath's multline environment: the label simply doesn't show
> up in the preview of these equations.  This has previously been reported
> in http://www.mail-archive.com/address@hidden/msg00653.html quite a
> few years ago.  As I rely quite heavily on this option (I think reftex
> doesn't use the previews so it isn't as convenient), this bug is rather
> annoying.

RefTeX works directly with the LaTeX source, not the typeset output.

> Using the attached test file, I think I have found the problem.  When
> the multline environment is used, the content is expanded twice in
> amsmath.sty's \multline@, the first time for measurement only.
> address@hidden is thus also called twice, but the second time \next is
> equal to address@hidden and processing get skipped.

Thanks for debugging this.

> If I remove this
> duplication check, by editing the definition of address@hidden in
> prshowlabels.def:
>
> -   address@hidden
> +   \iffalse\egroup\romannumeral\else
>
> Labels then show up normally.

Hm, but AFAIU this would also remove the feature that labels equal to
the last one are ignored.  I'm not sure when a situation with multiple
identical labels usually occurs.  I could provoke that by using "eq:foo"
in your test file where you had "eq:foo1" and "eq:foo2" but I am not
sure if this is what David had in mind when he wrote the code.

David, could you please comment?

-- 
Ralf