bug#13942: 24.3.50; `smie-auto-fill' loops

[Dirk Ullrich]

Prerequisits:
1. An Emacs with recent-enough `lisp/emacs-lisp/smie.el' module such
that `smie-auto-fill' is provided.
2. A ProofGeneral (PG) with its Coq mode based on `smie' (and
`load-path' properly set).
3. A Coq file with a comment longer than `fill-column'.

How to reproduce the bug:
1. Initialize PG by loading `pg-init.el'.
2. Enable auto-filling for PG's Coq mode.
3. Load the Coq test file, and trigger auto-filling by placing the
cursor just after a to-long comment line and hitting ENTER. -> Emacs
loops.

Remarks:
1. A debugger session shows that the looping is caused by
`smie-auto-fill'.
2. A simple Coq test file is appended to this bug report.



In GNU Emacs 24.3.50.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.4.2)
 of 2013-03-13 on koan
Windowing system distributor `The X.Org Foundation', version 11.0.11204000
System Description:     Debian GNU/Linux 7.0 (wheezy)

Configured using:
 `configure --prefix=/usr/local/packages/emacs-devel --sysconfdir=/etc
 --mandir=/usr/local/packages/emacs-devel/share/man
 --localstatedir=/var/local/packages/emacs-devel
 --libexecdir=/usr/local/packages/emacs-devel/lib
 --enable-locallisppath=/etc/emacs --without-sound
 --with-gameuser=packages --program-suffix=-devel --with-x-toolkit=gtk3'

Important settings:
  value of $LANG: de_DE.UTF-8
  locale-coding-system: utf-8-unix
  default enable-multibyte-characters: t

Major mode: Coq

Minor modes in effect:
  holes-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  auto-fill-function: smie-auto-fill
  transient-mark-mode: t

Recent input:
C-x C-f P <tab> . <tab> <return> M-x a u <tab> - f
<tab> <return> <end> SPC <backspace> C-x C-s <up> M-q
C-x u <down> <return> C-x C-s <return> <C-end> <backspace>
<backspace> <backspace> C-x C-s <return> <down> <down>
<backspace> C-x C-s M-x e m a <tab> <tab> <backspace>
<backspace> <backspace> <backspace> <backspace> <backspace>
r e p o r t <tab> <return>

Recent messages:
Wrote /common/depot/unfinished/2do/emacs-devel/smie-auto-fill/PG_Autofill.v
Quit
Mark set
Saving file 
/common/depot/unfinished/2do/emacs-devel/smie-auto-fill/PG_Autofill.v...
Wrote /common/depot/unfinished/2do/emacs-devel/smie-auto-fill/PG_Autofill.v
Quit
End of buffer
Saving file 
/common/depot/unfinished/2do/emacs-devel/smie-auto-fill/PG_Autofill.v...
Wrote /common/depot/unfinished/2do/emacs-devel/smie-auto-fill/PG_Autofill.v
Making completion list...

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev
gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util
mail-prsvr mail-utils help-mode vc-git which-func imenu coq
coq-smie-lexer smie coq-indent coq-par-compile coq-seq-compile
coq-compile-common coq-abbrev coq-local-vars local-vars-list coq-syntax
coq-db holes proof proof-shell pg-user completion pg-goals pg-response
proof-toolbar pg-assoc proof-tree proof-script proof-menu cus-edit
cus-start cus-load wid-edit span proof-auxmodes proof-utils scomint
proof-syntax advice help-fns bufhist easy-mmode ring proof-splash
derived pg-custom proof-config proof-faces proof-useropts pg-pamacs
proof-compat easymenu proof-site proof-autoloads cl-macs gv cl nadvice
cl-lib pg-vars time-date tooltip ediff-hook vc-hooks lisp-float-type
mwheel x-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list newcomment lisp-mode register page menu-bar rfn-eshadow
timer select scroll-bar mouse jit-lock font-lock syntax facemenu
font-core frame cham georgian utf-8-lang misc-lang vietnamese tibetan
thai tai-viet lao korean japanese hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer loaddefs button faces
cus-face macroexp files text-properties overlay sha1 md5 base64 format
env code-pages mule custom widget hashtable-print-readable backquote
make-network-process dbusbind inotify dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty emacs)

PG_Autofill.v
Description: Binary data