bug#22717: 25.0.91; sh-mode indentation bug with opening parens at the beginnings of lines, and apostrophes

[Phil Sainty]

I've come up with the following test case:

#!/bin/sh
echo "
(" # Opening parenthesis at the beginning of a line

if true; then
    # Here's an apostrophe
fi # ...and now this will be indented -- aligned with the apostrophe


If you auto-indent that, the final line gets indented to align
with the column containing the apostrophe in the preceding comment.


I've been working through a very large shell script trying to
eliminate indentation issues, and I discovered that quotes in
comments could cause problems with the indentation of later
lines of code.

Balanced apostrophes 'like so' seem to be ok in general, but
sometimes unbalanced quotes would cause subsequent issues.

I noticed the opening parenthesis bit while trying to narrow
this down to a small test case, and have subsequently confirmed
that inserting a space before all such line-starting opening
parens eliminates all of my problems with commented quotes.

My initial workaround had been to convert unbalanced commented
apostrophes into a unicode RIGHT SINGLE QUOTATION MARK, and
that resolved most of the problems I was seeing.

I found one instance in my large script where double quotes were
an issue, such that changing "emacsclient -a ''" in a comment
(including both types of quote) into just emacsclient -a '' (i.e.
removing the double quotes) resolved the issue.

I also saw occasional (but not consistent) issues with `symbol'
style quotes, and I ended up replacing the backticks with normal
apostrophes for all of those instances.

(But again, the opening paren seems to be the trigger.)

This was mostly with 24.5, but I've just checked my test case
with the current emacs-25 branch from git, and replicated the
problem.

I found one other consistent indentation issue, which I'll post
as a separate bug, as it seems like a different issue.


-Phil






In GNU Emacs 25.0.91.1 (x86_64-unknown-linux-gnu, X toolkit, Xaw3d 
scroll bars)
 of 2016-02-18 built on shodan
Repository revision: 14aec913ac3f0dd408487c0e8327403e0f239964
Windowing system distributor 'The X.Org Foundation', version 11.0.11701000
System Description:     Ubuntu 15.04

Configured using:
 'configure --prefix=/home/phil/emacs/trunk/usr/local
 --with-x-toolkit=lucid --without-sound'

Configured features:
XAW3D XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK DBUS GSETTINGS NOTIFY
GNUTLS LIBXML2 FREETYPE XFT ZLIB TOOLKIT_SCROLL_BARS LUCID X11

Important settings:
  value of $LANG: en_NZ.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8

Major mode: Shell-script

Minor modes in effect:
  sh-electric-here-document-mode: t
  show-paren-mode: t
  minibuffer-depth-indicate-mode: t
  winner-mode: t
  global-hl-line-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
GNU Emacs 25.0.91.1 (x86_64-unknown-linux-gnu, X toolkit, Xaw3d scroll 
bars) of 2016-02-18
Mark set [5 times]
Setting up indent for shell type sh
Indentation variables are now local.
Indentation setup for shell type sh
Mark activated
Indenting region...done
Undo!
funcall-interactively: End of buffer

Load-path shadows:
None found.

Features:
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Memory information:
((conses 16 93900 8317)
 (symbols 48 20374 0)
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 (strings 32 17885 4311)
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