bug#20820: 25.0.50; [PATCH] Default for reftex-label-regexps is too loose

[Nils Ackermann <nils@ackermath.info>]

The following valid latex test file shows the problem:

====
\documentclass{article}
\usepackage{enumitem}

\begin{document}
\section{A}
 [
\section{B}
  \begin{enumerate}[label=a]
  \item 
  \end{enumerate}
\end{document}
====

After loading `reftex', calling `reftex-toc' in the buffer with above
test file results in the following output:

====
TABLE-OF-CONTENTS on /path/to/test.tex
SPC=view TAB=goto RET=goto+hide [q]uit [r]escan [l]abels [f]ollow [x]r [?]Help
------------------------------------------------------------------------------
     1 A

====

while the following would be expected:

====
TABLE-OF-CONTENTS on /path/to/test.tex
SPC=view TAB=goto RET=goto+hide [q]uit [r]escan [l]abels [f]ollow [x]r [?]Help
------------------------------------------------------------------------------
     1 A
     2 B

====

The default regexp in reftex-label-regexps consumes everything from the
first opening `[' until the `label=' clause, hiding relevant material in
between.

This is a problem because in mathematics texts unbalanced brackets
appear commonly.  The gobbled up text is then not accessible from reftex
anymore.

Proposed fix:

---
 lisp/textmodes/reftex-vars.el | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/textmodes/reftex-vars.el b/lisp/textmodes/reftex-vars.el
index 7f050e9..4eb0432 100644
--- a/lisp/textmodes/reftex-vars.el
+++ b/lisp/textmodes/reftex-vars.el
@@ -876,7 +876,7 @@ DOWNCASE    t:   Downcase words before using them."
       "\\\\label{\\(?1:[^}]*\\)}"
       ;; keyvals [..., label = {foo}, ...] forms used by ctable,
       ;; listings, minted, ...
-      "\\[[^]]*\\<label[[:space:]]*=[[:space:]]*{?\\(?1:[^],}]+\\)}?")
+      "\\[[^[]]*\\<label[[:space:]]*=[[:space:]]*{?\\(?1:[^],}]+\\)}?")
     "List of regexps matching \\label definitions.
 The default value matches usual \\label{...} definitions and
 keyval style [..., label = {...}, ...] label definitions.  It is
-- 
1.9.1

In GNU Emacs 25.0.50.1 (x86_64-unknown-linux-gnu)
 of 2015-06-15 on aphrodite
Repository revision: f0f216eaa1ebc84457812f66a5e714721245ef9d
System Description:	Ubuntu 14.04.1 LTS

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