bug#21366: 11.88.6; Vertical bar is paired delimiter in syntax table

[Michael Hoffman]

The vertical bar (|) is paired delimiter/math mode ("$") in the TeX 
syntax table. This means that balanced vertical bars are expected just 
as balanced parentheses. This causes problems with S-expression movement 
and Flyspell when there are odd numbers of vertical bars. The easiest 
way to reproduce a problem this causes:

1. Create test1.tex with contents:

{|{}|{}|}

2. Go to beginning of buffer and type C-M-f (forward-sexp)

What I expected to happen:

Cursor moves to last closing curly brace.

What happens instead:

I receive the error:

forward-sexp: Scan error: "Unbalanced parentheses", 1, 11

This sort of unbalanced vertical bar is likely to happen in table 
definitions.

Workaround:

Add this to .emacs:

(with-eval-after-load 'tex
   (modify-syntax-entry ?| "." TeX-mode-syntax-table))

I don't understand why | is treated as a paired delimiter in the first 
place, though.

------------------------------------------------------------------------



Emacs  : GNU Emacs 24.5.2 (x86_64-unknown-linux-gnu, GTK+ Version 3.8.8)
 of 2015-07-29 on mhoffman2.uhnres.utoronto.ca
Package: 11.88.6

current state:
==============
(setq
 AUCTeX-date "2015-05-08"
 window-system 'x
 LaTeX-version "2e"
 TeX-style-path '("~/.emacs.d/auctex" 
"/users/mhoffman/.emacs.d/elpa/auctex-11.88.6/style"
                  "/users/mhoffman/.emacs.d/auctex/auto" 
"/users/mhoffman/.emacs.d/auctex/style"
                  "auto" "style")
 TeX-auto-save t
 TeX-parse-self t
 TeX-master t
 TeX-command-list '(("Make" "make LATEX=\"%`%l%(mode)\"" TeX-run-TeX t 
t :help "Run make")
                    ("Latexmk" "latexmk -pdf %s" TeX-run-TeX nil t 
:help "Run Latexmk")
                    ("TeX" "%(PDF)%(tex) %(file-line-error) 
%(extraopts) %`%S%(PDFout)%(mode)%' %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) %t" 
TeX-run-compile nil (texinfo-mode) :help
                     "Run Makeinfo with Info output")
                    ("Makeinfo HTML" "makeinfo %(extraopts) --html %t" 
TeX-run-compile nil
                     (texinfo-mode) :help "Run Makeinfo with HTML output")
                    ("AmSTeX" "%(PDF)amstex %(extraopts) 
%`%S%(PDFout)%(mode)%' %t" TeX-run-TeX nil
                     (ams-tex-mode) :help "Run AMSTeX")
                    ("ConTeXt" "texexec --once --texutil %(extraopts) 
%(execopts)%t" TeX-run-TeX nil
                     (context-mode) :help "Run ConTeXt once")
                    ("ConTeXt Full" "texexec %(extraopts) 
%(execopts)%t" TeX-run-TeX nil
                     (context-mode) :help "Run ConTeXt until completion")
                    ("BibTeX" "bibtex %s" TeX-run-BibTeX nil t :help 
"Run BibTeX")
                    ("Biber" "biber %s" TeX-run-Biber nil t :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-command t t 
:help
                     "Generate PostScript file")
                    ("Index" "makeindex %s" TeX-run-command nil t :help 
"Create index file")
                    ("Xindy" "texindy %s" TeX-run-command nil t :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"))
 )