bug#48518: 13.0.11; LaTeX environment C-c C-e on region doesn't indent properly

[Berthold Lorke]

Whenever I highlight a region and do C-c C-e of any kind, the result
will not have the text indented correctly, and the closing
"\end{environment}" will also not be indented correctly.  Merely the
"\begin{environment} is indented correctly.

Steps to reproduce:

 1. Install auctex
 2. Open a tex file (in latex-mode)
 3. Start an intented environment, such as a section
 4. Write some text
 5. Highlight that text
 6. Perform LaTeX-environment (C-c C-e) on that highlighted region

Example:

```tex
\documentclass{article}
\begin{document}
Hello.
\begin{section}
  Here is a text.

  With some paragraphs.

  Here is a third paragraph.
\end{section}
\end{document}
```

After the steps:

```tex
\documentclass{article}
\begin{document}
Hello.
\begin{section}
  \begin{environment}
  Here is a text.

  With some paragraphs.

  Here is a third paragraph.
\end{environment}
\end{section}
\end{document}
```

It is easily fixed if I rehighlight the text and press tab (indent
region), but this is tedious.  I should try to debug this myself, or
hotfix this by just writing a hook, but it should be easy to fix, and it
is a good exercise for me, but I am too lazy, sorry.

Best wishes
Berthold Lorke


Emacs  : GNU Emacs 27.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version
3.24.27, cairo version 1.17.4)
 of 2021-03-26
Package: 13.0.11

current state:
==============
(setq
 AUCTeX-date "2021-04-28"
 window-system 'x
 LaTeX-version "2e"
 TeX-style-path '("~/.emacs.d/auctex"
"/tmp/.emacs.d/elpa/auctex-13.0.11/style" "/tmp/.emacs.d/auctex/auto"
                  "/tmp/.emacs.d/auctex/style" "auto" "style")
 TeX-auto-save nil
 TeX-parse-self nil
 TeX-master t
 TeX-command-list '(("TeX" "%(PDF)%(tex) %(file-line-error)
%`%(extraopts) %S%(PDFout)%(mode)%' %(output-dir) %t"
                     TeX-run-TeX nil (plain-tex-mode ams-tex-mode texinfo-mode) 
:help
"Run plain TeX")
                    ("LaTeX" "%`%l%(mode)%' %T" TeX-run-TeX nil (latex-mode
doctex-mode) :help "Run LaTeX")
                    ("Makeinfo" "makeinfo %(extraopts) %(o-dir) %t" 
TeX-run-compile
nil (texinfo-mode) :help
                     "Run Makeinfo with Info output")
                    ("Makeinfo HTML" "makeinfo %(extraopts) %(o-dir) --html %t"
TeX-run-compile nil (texinfo-mode)
                     :help "Run Makeinfo with HTML output")
                    ("AmSTeX" "amstex %(PDFout) %`%(extraopts) %S%(mode)%'
%(output-dir) %t" TeX-run-TeX nil
                     (ams-tex-mode) :help "Run AMSTeX")
                    ("ConTeXt" "%(cntxcom) --once --texutil %(extraopts)
%(execopts)%t" TeX-run-TeX nil
                     (context-mode) :help "Run ConTeXt once")
                    ("ConTeXt Full" "%(cntxcom) %(extraopts) %(execopts)%t"
TeX-run-TeX nil (context-mode) :help
                     "Run ConTeXt until completion")
                    ("BibTeX" "bibtex %(O?aux)" TeX-run-BibTeX nil
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode
context-mode) :help
                     "Run BibTeX")
                    ("Biber" "biber %s %(output-dir)" TeX-run-Biber nil
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode)
:help "Run Biber")
                    ("View" "%V" TeX-run-discard-or-function t t :help "Run 
Viewer")
                    ("Print" "%p" TeX-run-command t t :help "Print the file")
                    ("Queue" "%q" TeX-run-background nil t :help "View the 
printer
queue" :visible
                     TeX-queue-command)
                    ("File" "%(o?)dvips %d -o %f " TeX-run-dvips t
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode)
:help
                     "Generate PostScript file")
                    ("Dvips" "%(o?)dvips %d -o %f " TeX-run-dvips nil
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode)
:help
                     "Convert DVI file to PostScript")
                    ("Dvipdfmx" "dvipdfmx %d -o %(O?pdf)" TeX-run-dvipdfmx nil
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode)
:help
                     "Convert DVI file to PDF with dvipdfmx")
                    ("Ps2pdf" "ps2pdf %f %(O?pdf)" TeX-run-ps2pdf nil
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode)
:help
                     "Convert PostScript file to PDF")
                    ("Glossaries" "makeglossaries %(O?aux)" TeX-run-command nil
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode)
:help
                     "Run makeglossaries to create glossary\n     file")
                    ("Index" "makeindex %(O?idx)" TeX-run-index nil
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode)
:help
                     "Run makeindex to create index file")
                    ("upMendex" "upmendex %(O?idx)" TeX-run-index t
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode)
:help
                     "Run upmendex to create index file")
                    ("Xindy" "texindy %s" TeX-run-command nil
                     (plain-tex-mode latex-mode doctex-mode ams-tex-mode 
texinfo-mode)
:help
                     "Run xindy to create index file")
                    ("Check" "lacheck %s" TeX-run-compile nil (latex-mode) :help
                     "Check LaTeX file for correctness")
                    ("ChkTeX" "chktex -v6 %s" TeX-run-compile nil (latex-mode) 
:help
                     "Check LaTeX file for common mistakes")
                    ("Spell" "(TeX-ispell-document \"\")" TeX-run-function nil 
t :help
"Spell-check the document")
                    ("Clean" "TeX-clean" TeX-run-function nil t :help "Delete
generated intermediate files")
                    ("Clean All" "(TeX-clean t)" TeX-run-function nil t :help
                     "Delete generated intermediate and output files")
                    ("Other" "" TeX-run-command t t :help "Run an arbitrary 
command"))
 )