From: Quek Yu Han <qythium@gmail.com>
To: 33890@debbugs.gnu.org
Subject: bug#33890: 27.0.50; Incorrect behaviour of cl-loop macro
Date: Thu, 27 Dec 2018 04:28:59 -0500 [thread overview]
Message-ID: <CAGCUw0jQX_rp7ZhmFr4FLUmH0BUzeR48MObuFR-CHX5LsuTMvA@mail.gmail.com> (raw)
It appears that a change to the `cl-loop` macro in Emacs 27 introduced a
bug where certain clauses would be evaluated more than once in a loop
with a "when" clause.
See the following minimal example which finds the index of an element in
a list:
(cl-loop
for x in '(a b c d e)
for index = 0 then (1+ index)
when (eq x 'e)
return index)
In Emacs 26.1 this returns `4` as expected, but in Emacs 27.0.50 it
returns `7`, due to the index being incremented twice per loop. The same
occurs after a `emacs -Q` restart.
For reference here is the macroexpanded form of the above expression,
with the difference between 26 and 27 outlined (everything else is
identical):
(cl-block nil
(let* ((--cl-var-- '(a b c d e))
(x nil)
(index nil)
(--cl-var-- t)
(--cl-var-- t)
--cl-var--)
(while (and (consp --cl-var--)
(progn
(setq x (car --cl-var--))
(setq index
(if --cl-var-- 0 (1+ index)))
(if (eq x 'e)
(setq --cl-var-- index
--cl-var-- nil)
t)))
(setq --cl-var-- (cdr --cl-var--))
;;;============== ADDED IN EMACS 27 =================
(and (and (consp --cl-var--)
(progn
(setq x (car --cl-var--))
(setq index
(if --cl-var-- 0 (1+ index)))
(if (eq x 'e)
(setq --cl-var-- index
--cl-var-- nil)
t))))
;;;==================================================
(setq --cl-var-- nil))
--cl-var--))
Thanks!
In GNU Emacs 27.0.50 (build 1, x86_64-apple-darwin17.6.0, NS
appkit-1561.40 Version 10.13.5 (Build 17F77))
of 2018-07-08 built on QYH.local
Repository revision: 98463bed07ecc9057094928ffdc2321eaaf3ab52
Windowing system distributor 'Apple', version 10.3.1671
System Description: Mac OS X 10.14.2
Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Configured using:
'configure --disable-dependency-tracking --disable-silent-rules
--enable-locallisppath=/usr/local/share/emacs/site-lisp
--infodir=/usr/local/Cellar/emacs-plus/HEAD-98463be/share/info/emacs
--prefix=/usr/local/Cellar/emacs-plus/HEAD-98463be --with-xml2
--without-dbus --with-gnutls --with-imagemagick --with-modules
--with-rsvg --with-xwidgets --with-ns --disable-ns-self-contained'
Configured features:
RSVG IMAGEMAGICK NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS
MODULES THREADS XWIDGETS LCMS2
Important settings:
value of $LC_ALL: en_US.UTF-8
value of $LC_CTYPE: UTF-8
value of $LANG: en_US.UTF-8
locale-coding-system: utf-8-unix
Major mode: Lisp Interaction
Minor modes in effect:
tooltip-mode: t
global-eldoc-mode: t
eldoc-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
auto-composition-mode: t
auto-encryption-mode: t
auto-compression-mode: t
line-number-mode: t
transient-mark-mode: t
Load-path shadows:
None found.
Features:
(shadow sort mail-extr emacsbug message rmc puny seq byte-opt gv
bytecomp byte-compile cconv dired dired-loaddefs format-spec rfc822 mml
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rmail rmail-loaddefs mm-decode mm-bodies mm-encode mail-parse rfc2231
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rfc2045 ietf-drums mm-util mail-prsvr mail-utils elec-pair time-date
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mwheel term/ns-win ns-win ucs-normalize mule-util term/common-win
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newcomment text-mode elisp-mode lisp-mode prog-mode register page
menu-bar rfn-eshadow isearch timer select scroll-bar mouse jit-lock
font-lock syntax facemenu font-core term/tty-colors frame cl-generic
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 charscript charprop
case-table epa-hook jka-cmpr-hook help simple abbrev obarray minibuffer
cl-preloaded nadvice loaddefs button faces cus-face macroexp files
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custom widget hashtable-print-readable backquote xwidget-internal kqueue
cocoa ns lcms2 multi-tty make-network-process emacs)
Memory information:
((conses 16 203880 9574)
(symbols 48 20001 1)
(miscs 40 33 114)
(strings 32 28869 1418)
(string-bytes 1 768776)
(vectors 16 35252)
(vector-slots 8 725502 18860)
(floats 8 47 69)
(intervals 56 230 0)
(buffers 992 11))
next reply other threads:[~2018-12-27 9:28 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-27 9:28 Quek Yu Han [this message]
2018-12-31 6:22 ` bug#33890: 27.0.50; Incorrect behaviour of cl-loop macro Glenn Morris
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