bug#15074: 24.3; Possible typo in the Elisp Reference Manual - section 2.3.3.4

bug#15074: 24.3; Possible typo in the Elisp Reference Manual - section 2.3.3.4

[Sian Mountbatten]

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This bug report will be sent to the Bug-GNU-Emacs mailing list
and the GNU bug tracker at debbugs.gnu.org.  Please check that
the From: line contains a valid email address.  After a delay of up
to one day, you should receive an acknowledgment at that address.

Please write in English if possible, as the Emacs maintainers
usually do not have translators for other languages.

Please describe exactly what actions triggered the bug, and
the precise symptoms of the bug.  If you can, give a recipe
starting from `emacs -Q':

In section 2.3.3.4 of the Elisp Reference Manual, this sentence occurs:
    The integer that represents such a character has the $2^{27}$ bit
    set.

I have expressed the number using the TeX/LaTeX manner. The
point is that, in the following paragraph, the text refers to the
$2^7$ bit. I suspect, therefore, that the 27 mentioned should really
be 7. If 27 was intended, that would mean that char tables would have
to accommodate more than 134 million characters! Surely not!

In GNU Emacs 24.3.1 (x86_64-pc-linux-gnu, GTK+ Version 3.8.2)
  of 2013-06-25 on sochi, modified by Debian
Windowing system distributor `The X.Org Foundation', version 11.0.11204000
System Description:    Debian GNU/Linux unstable (sid)

Configured using:
  `configure '--build' 'x86_64-linux-gnu' '--build' 'x86_64-linux-gnu'
  '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib'
  '--localstatedir=/var/lib' '--infodir=/usr/share/info'
  '--mandir=/usr/share/man' '--with-pop=yes'
  '--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.3/site-lisp:/usr/share/emacs/site-lisp'
  '--with-crt-dir=/usr/lib/x86_64-linux-gnu' '--with-x=yes'
  '--with-x-toolkit=gtk3' '--with-toolkit-scroll-bars'
  'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fstack-protector
  --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall'
  'LDFLAGS=-Wl,-z,relro' 'CPPFLAGS=-D_FORTIFY_SOURCE=2''

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

Major mode: Emacs-Lisp

Minor modes in effect:
   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
   column-number-mode: t
   line-number-mode: t
   transient-mark-mode: t

Recent input:
<down> <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <up> <right> <right> <right> <right>
<right> <right> <right> <right> <right> <right> <right>
<right> SPC I SPC s h a k l <backspace> <backspace>
l l SPC a l s o SPC l o o k SPC i n t o SPC t h e SPC
p o s s i b i l i t y SPC o f SPC m a k i n g SPC G
W M SPC u s e SPC t h e SPC G T K + SPC G U I SPC t
o o l k i t SPC w h i c h SPC m i g h t SPC e n a b
l e SPC t h e SPC D r a n g <backspace> <backspace>
g - a n d - D r o p SPC c a p a b i l i t y SPC o f
SPC R O X - F i l e r SPC ( m y SPC p r e f e r r e
d SPC f i l e SPC m a n a g e r ) . <right> <right>
<right> <left> <left> <left> SPC S o , SPC h e r e
SPC I S-SPC a m SPC <backspace> , SPC u s i n g SPC
G W M SPC a s SPC m y SPC w i n d o w SPC m a n a g
e r . <right> <right> <right> <right> <right> C-x C-s
<help-echo> <help-echo> <help-echo> <help-echo> C-x
k <return> <down> <down> <down> <down> <down> <down>
<down> <down> <down> <down> <down> <up> <right> <right>
<right> <right> <right> <help-echo> <menu> r e p o
SPC r SPC e m SPC SPC <return>

Recent messages:
Auto-saving...done
Saving file /home/sian/Retejo/blog/engblog.html...
Wrote /home/sian/Retejo/blog/engblog.html
Auto-saving...done
Auto-saving...done
Auto-saving...done
Auto-saving...done
Saving file /home/sian/Retejo/blog/engblog.html...
Wrote /home/sian/Retejo/blog/engblog.html
Making completion list...

Load-path shadows:
/usr/share/emacs/24.3/site-lisp/debian-startup hides 
/usr/share/emacs/site-lisp/debian-startup
/usr/share/emacs24/site-lisp/dictionaries-common/ispell hides 
/usr/share/emacs/24.3/lisp/textmodes/ispell
/usr/share/emacs24/site-lisp/dictionaries-common/flyspell hides 
/usr/share/emacs/24.3/lisp/textmodes/flyspell

Features:
(shadow mail-extr emacsbug message rfc822 mml mml-sec mm-decode
mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader
sendmail rfc2047 rfc2045 ietf-drums mail-utils skeleton sgml-mode
apropos sort bookmark help-mode help-fns jka-compr info easymenu
erc-goodies erc erc-backend erc-compat format-spec auth-source eieio
byte-opt bytecomp byte-compile cconv gnus-util mm-util mail-prsvr
password-cache thingatpt pp saveplace 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 dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty emacs)

-- 
Sian Mountbatten (home web-site http://www.poenikatu.co.uk/>)
Learning C++11 from the C++ Primer 5th edition.
I'm an associate FSF member (no. 10888).
Help us support software freedom! http://www.fsf.org/jf?referrer=10888

-- 
Sian Mountbatten (home web-site http://www.poenikatu.co.uk/>)
Learning C++11 from the C++ Primer 5th edition.
I'm an associate FSF member (no. 10888).
Help us support software freedom! http://www.fsf.org/jf?referrer=10888


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bug#15074: 24.3; Possible typo in the Elisp Reference Manual - section 2.3.3.4

[Eli Zaretskii]

> Date: Mon, 12 Aug 2013 09:38:57 +0100
> From: Sian Mountbatten <poenikatu@fastmail.co.uk>
> 
> In section 2.3.3.4 of the Elisp Reference Manual, this sentence occurs:
>     The integer that represents such a character has the $2^{27}$ bit
>     set.
> 
> I have expressed the number using the TeX/LaTeX manner. The
> point is that, in the following paragraph, the text refers to the
> $2^7$ bit. I suspect, therefore, that the 27 mentioned should really
> be 7.

No, it's not a typo: the META modifier bit of a character is indeed
0x8000000.

> If 27 was intended, that would mean that char tables would have
> to accommodate more than 134 million characters! Surely not!

As a matter of fact, char tables can accommodate all the Unicode
character space, but they do that in an efficient way, not by
allocating a flat array.  Nevertheless, the META bit is unrelated to
the capacity of a char table, since modifiers are not stored there.