Hi Tassilo,

2014-12-09 10:34 GMT+01:00 Tassilo Horn <tsdh@gnu.org>:
>> Or matching everything between the opening and the closing brace
>> (allowing at least one level of braces)?
>
> Either that, or we could also rely on syntax tables.  I.e., since
> `LaTeX-find-matching-end' already brings us to the end of the
> environment name,
>
>   (let ((end (point)))
>     (forward-char)
>     (backward-sexp)
>     (forward-char)
>     (buffer-substring-no-properties (point) end))
>
> gives us the environment name.

Good idea, except that `LaTeX-find-matching-end' fails to find the
closing brace of \end when the environment name is a macro with
arguments.  The attached patch should fix this problem.
`LaTeX-environment-name-regexp' needs to be a function because if it
were a variable it would always keep the original value, also in
buffers with different values for `TeX-grop' and `TeX-grcl' (or not?).
Probably `LaTeX-modify-environment' can be simplified following your
suggestion, the patch sketches an idea how to fix
`LaTeX-find-matching-end', but can be improved.

Bye,
Mosè