GNU bug report logs - #79621
31.0.50; rx macro fails an obvious sanity test (match index off by one)

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Lockywolf <for_emacs_1 <at> lockywolf.net>
To: bug-gnu-emacs <at> gnu.org
Subject: 31.0.50; rx macro fails an obvious sanity test (match index off by
 one)
Date: Tue, 14 Oct 2025 17:18:07 +0800

[Message part 1 (text/plain, inline)]

(with-temp-buffer
  (insert "hello Emacs world")
  (string-match (rx (group (+ anychar))
                    (group "Emacs"))
                (buffer-string))
 (match-string 1))
=>
(args-out-of-range #<buffer  *temp*> 0 6)

In fact, args should be 1 and 7, not 0 and 6.


In GNU Emacs 31.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
 3.24.31, cairo version 1.16.0) of 2025-09-27 built on
 laptop.lockywolf.net
Repository revision: 339003c9db6a4d48734f199e955e2d9caa26a8f8
Repository branch: ispell-tests-2
Windowing system distributor 'The X.Org Foundation', version 11.0.12014000
System Description: Slackware 15.0 x86_64

Configured using:
 'configure 'CC=ccache gcc'
 PKG_CONFIG_PATH=/opt/cuda-12.6/usr/lib64/pkgconfig/:/opt/cuda-12.6/usr/lib64/pkgconfig/:/opt/cuda-12.6/usr/lib64/pkgconfig/::/usr/local/lib64/pkgconfig:/usr/local/share/pkgconfig:/usr/local/lib64/pkgconfig:/usr/local/share/pkgconfig:/usr/local/lib64/pkgconfig:/usr/local/share/pkgconfig'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND
SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XDBE XIM
XINERAMA XINPUT2 XPM XRANDR GTK3 ZLIB

Important settings:
  value of $LC_COLLATE: C
  value of $LC_TIME: en_GB.UTF-8
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  show-paren-mode: t
  electric-indent-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
  minibuffer-nonselected-mode: t
  minibuffer-regexp-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug lisp-mnt message mailcap yank-media puny
dired dired-loaddefs rfc822 mml mml-sec password-cache epa derived epg
rfc6068 epg-config gnus-util text-property-search time-date subr-x
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-fns radix-tree cl-print byte-opt gv bytecomp
byte-compile debug backtrace help-mode find-func rx warnings icons
cl-loaddefs cl-lib rmc iso-transl tooltip cconv eldoc paren electric
uniquify ediff-hook vc-hooks lisp-float-type elisp-mode mwheel
term/x-win x-win term/common-win x-dnd touch-screen tool-bar dnd fontset
image regexp-opt fringe tabulated-list replace newcomment text-mode
lisp-mode prog-mode register page tab-bar menu-bar rfn-eshadow isearch
easymenu timer select scroll-bar mouse jit-lock font-lock syntax
font-core term/tty-colors frame minibuffer nadvice seq simple cl-generic
indonesian philippine cham georgian utf-8-lang misc-lang vietnamese
tibetan thai tai-viet lao korean japanese eucjp-ms cp51932 hebrew greek
romanian slovak czech european ethiopic indian cyrillic chinese
composite emoji-zwj charscript charprop case-table epa-hook
jka-cmpr-hook help abbrev obarray oclosure cl-preloaded button loaddefs
theme-loaddefs faces cus-face macroexp files window text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget keymap
hashtable-print-readable backquote threads dbusbind inotify lcms2
dynamic-setting system-font-setting font-render-setting cairo gtk
x-toolkit xinput2 x multi-tty move-toolbar make-network-process
tty-child-frames emacs)

Memory information:
((conses 16 55798 9505) (symbols 48 6818 0) (strings 32 17100 1779)
 (string-bytes 1 440015) (vectors 16 12339)
 (vector-slots 8 136277 10985) (floats 8 24 9) (intervals 56 512 0)
 (buffers 1064 13))

[Message part 2 (text/plain, inline)]

-- 
Your sincerely,
Vladimir Nikishkin (MiEr, lockywolf)
(Laptop)

[signature.asc (application/pgp-signature, inline)]

Message #8 received at 79621 <at> debbugs.gnu.org (full text, mbox):

From: Michael Heerdegen <michael_heerdegen <at> web.de>
To: Lockywolf <for_emacs_1 <at> lockywolf.net>
Cc: 79621 <at> debbugs.gnu.org
Subject: Re: bug#79621: 31.0.50; rx macro fails an obvious sanity test
 (match index off by one)
Date: Tue, 14 Oct 2025 11:53:52 +0200

Lockywolf <for_emacs_1 <at> lockywolf.net> writes:

> (with-temp-buffer
>   (insert "hello Emacs world")
>   (string-match (rx (group (+ anychar))
>                     (group "Emacs"))
>                 (buffer-string))
>  (match-string 1))
> =>
> (args-out-of-range #<buffer  *temp*> 0 6)
>
> In fact, args should be 1 and 7, not 0 and 6.

Your problem is not about `rx', since specifying the regexp in string
form leads to the same result:

#+begin_src emacs-lisp
(with-temp-buffer
  (insert "hello Emacs world")
  (string-match "\\([^z-a]+\\)\\(Emacs\\)"
                (buffer-string))
 (match-string 1))
#+end_src

Please note this paragraph in (info "(elisp) Simple Match Data"):

|  -- Function: match-string count &optional in-string
|    [...]
|    If the last such operation was done against a string with
|    ‘string-match’, then you should pass the same string as the
|    argument IN-STRING.  After a buffer search or match, you should
|    omit IN-STRING or pass ‘nil’ for it; but you should make sure that
|    the current buffer when you call ‘match-string’ is the one in which
|    you did the searching or matching.  Failure to follow this advice
|    will lead to incorrect results.

So your call is just wrong, you have to pass the string used for
matching.


Michael.

Message #11 received at 79621 <at> debbugs.gnu.org (full text, mbox):

From: Robert Pluim <rpluim <at> gmail.com>
To: Lockywolf <for_emacs_1 <at> lockywolf.net>
Cc: 79621 <at> debbugs.gnu.org
Subject: Re: bug#79621: 31.0.50; rx macro fails an obvious sanity test
 (match index off by one)
Date: Tue, 14 Oct 2025 11:53:50 +0200

>>>>> On Tue, 14 Oct 2025 17:18:07 +0800, Lockywolf <for_emacs_1 <at> lockywolf.net> said:

    Lockywolf> (with-temp-buffer
    Lockywolf>   (insert "hello Emacs world")
    Lockywolf>   (string-match (rx (group (+ anychar))
    Lockywolf>                     (group "Emacs"))
    Lockywolf>                 (buffer-string))
    Lockywolf>  (match-string 1))
    Lockywolf> =>
    Lockywolf> (args-out-of-range #<buffer  *temp*> 0 6)

    Lockywolf> In fact, args should be 1 and 7, not 0 and 6.

This is nothing to do with rx. When you call `match-string' after
`string-match' you have to pass the string again.

Robert
-- 

Message #16 received at 79621-done <at> debbugs.gnu.org (full text, mbox):

From: Lockywolf <for_emacs_1 <at> lockywolf.net>
To: 79621-done <at> debbugs.gnu.org
Subject: Re: bug#79621: Acknowledgement (31.0.50; rx macro fails an obvious
 sanity test (match index off by one))
Date: Tue, 14 Oct 2025 19:01:42 +0800

match-string should be called with the second argument

-- 
Your sincerely,
Vladimir Nikishkin (MiEr, lockywolf)
(Laptop)

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