"! File ended while scanning use of" error not handled correctly by TeX-next-error

[Rupert Levene]

Binary package hint: auctex

If I run emacs -q and load the following file, ~/test.tex:

\documentclass{beamer}
\begin{document}
\begin{frame}
  $a_{b$
\end{frame}
\end{document}

and hit C-c C-c LaTeX RET, emacs says "LaTeX errors in `*~/test output'. Use C-c ` to display."

Then I hit C-c ` and I expect one buffer called *TeX Help* to be created containing the "Missing } inserted" error, alongside the original test.tex buffer.

But this doesn't happen: instead, two buffers are created: one called *TeX Help*, and a read-only buffer called Debian. Both are empty, and the minibuffer says: Search failed: "^l\\." These two buffers replace the test.tex buffer.

Incidentally, if I go to the new Debian buffer and hit C-x C-w, the minibuffer says "Write file: ~/TeX Live 2009/", which I find rather curious.

If I comment out the \begin{frame} and \end{frame} lines in test.tex, then I do get the expected behaviour.

Version info:
$ lsb_release -rd
Description: Ubuntu 10.04.2 LTS
Release: 10.04
$ apt-cache policy emacs23 auctex
emacs23:
  Installed: 23.1+1-4ubuntu7.2
  Candidate: 23.1+1-4ubuntu7.2
  Version table:
 *** 23.1+1-4ubuntu7.2 0
        500 http://ftp.heanet.ie/pub/ubuntu/ lucid-updates/main Packages
        100 /var/lib/dpkg/status
     23.1+1-4ubuntu7 0
        500 http://ftp.heanet.ie/pub/ubuntu/ lucid/main Packages
auctex:
  Installed: 11.85-1ubuntu1
  Candidate: 11.85-1ubuntu1
  Version table:
 *** 11.85-1ubuntu1 0
        500 http://ftp.heanet.ie/pub/ubuntu/ lucid/main Packages
        100 /var/lib/dpkg/status

[era (era)]

Could you please enable debugging with (setq debug-on-error t) and repeat the repro steps, then attach the contents of the *Backtrace* buffer you will hopefully get when the error happens.

I am setting the Status of this bug report to Incomplete to mark it as pending on your input. It can be changed back to New once you supply the requested information. Thank you for your patience and cooperation.

[Rupert Levene (levene)]

Backtrace attached.

[Rupert Levene (levene)]

Here is the LaTeX log file. I imagine that the bug lies in the parsing of this file.

[era (era)]

I am able to reproduce this out of the box on 10.04.2 with emacs23 and auctex from the official repositories. Marking as Confirmed.

[Rupert Levene (levene)]

Here is a simpler test case:

\documentclass{article}
\begin{document}
\emph{
\end{document}

The problem seems to be that TeX-next-error expects every error in the log file to have a line number attached to it. But the error here is

! File ended while scanning use of \emph .

which doesn't generate a line number.

[era (era)]

I forwarded your bug to Debian's auctex maintainer. Thanks for your effort in diagnosing this!

[era (era)]

The Debian bug now has a small patch, from a Ubuntu user, no less.