bug#30568: 27.0.50; `rx' doesn't create optimal regex for (group (or ...))

[p.stephani2@gmail.com]

emacs -Q -batch --eval=3D'(progn (princ (rx (group (or "aaa" "bbb")))) (ter=
pri))'
=3D=3D> \(\(?:aaa\|bbb\)\)

This should generate \(aaa\|bbb\) instead.  Of course, these regexes are
equivalent, but the second one is easier to read (and maybe faster).


In GNU Emacs 27.0.50 (build 16, x86_64-pc-linux-gnu, GTK+ Version 3.22.24)
  of 2018-02-21 built on localhost
Repository revision: d599dce1353ce59d134fcff21cde02c70025253d
Windowing system distributor 'The X.Org Foundation', version 11.0.11903000
System Description: Debian GNU/Linux buster/sid

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
  'configure --without-threads --enable-gcc-warnings=3Dwarn-only
  --enable-gtk-deprecation-warnings --without-pop --with-mailutils
  --enable-checking --enable-check-lisp-object-type --with-modules
  'CFLAGS=3D-O0 -ggdb3''

Configured features:
XPM JPEG TIFF GIF PNG SOUND DBUS GSETTINGS NOTIFY GNUTLS FREETYPE XFT
ZLIB TOOLKIT_SCROLL_BARS GTK3 X11 MODULES JSON

Important settings:
   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 cl-loaddefs cl-lib dired dired-loaddefs
format-spec rfc822 mml easymenu mml-sec password-cache epa derived epg
epg-config gnus-util rmail rmail-loaddefs mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail rfc2047
rfc2045 ietf-drums mm-util mail-prsvr mail-utils elec-pair time-date
mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel term/x-win x-win term/common-win x-dnd tool-bar
dnd fontset image regexp-opt fringe tabulated-list replace 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
text-properties overlay sha1 md5 base64 format env code-pages mule
custom widget hashtable-print-readable backquote dbusbind inotify
dynamic-setting system-font-setting font-render-setting move-toolbar gtk
x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 95399 9075)
  (symbols 48 20247 1)
  (miscs 40 40 121)
  (strings 32 28348 1815)
  (string-bytes 1 757412)
  (vectors 16 14141)
  (vector-slots 8 499378 12892)
  (floats 8 50 67)
  (intervals 56 223 0)
  (buffers 992 12))

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