Hi all,

I noticed that TeX-find-macro-end doesn't work as expected way on, e.g.,

  \begin{enumerate}[a)]

The issue arose organically when folding such macros.

To see the basic issue, evaluate the following in scratch:

--8<---------------cut here---------------start------------->8---
(mapcar
 (lambda (str)
   (with-temp-buffer
     (LaTeX-mode)
     (insert str)
     (char-to-string (char-before (TeX-find-macro-end-helper (point-min))))))
 '("\begin{enumerate}[a]"
   "\begin{enumerate}[(a)]"
   "\begin{enumerate}[a)]"))
--8<---------------cut here---------------end--------------->8---

This returns ("]" "]" ")") but should return ("]" "]" "]").

The attached patch seems to address the issue by using a stripped syntax
table, which seems like a standard approach in tex.el.  Any feedback
would be welcome.

Paul