bug#42486: 28.0.50; Bug of feature/native-comp branch. Error message native-compile-async: Symbol’s value as variable is void: comp-native-path-postfix

[AllenDang]

Under MacOS v10.15.5

1. Launch Emacs GUI.
2. Scratch buffer, input (native-compile-async "~/.emacs.d/elpa/" 4 t).
3. M-x eval-buffer

Error message native-compile-async: Symbol’s value as variable is void:
comp-native-path-postfix appear in bottom message line.

The branch information is:
commit 37e0dbc97242a69da9f02039f5635261a307659a (HEAD -> feature/native-comp, 
origin/feature/native-comp, list)
Merge: 907618b3b5 5d2a83ea0e
Author: Andrea Corallo <akrl@sdf.org>
Date:   Sun Jul 19 20:39:27 2020 +0100

    Merge remote-tracking branch 'savannah/master' into HEAD

diff --cc lisp/gnus/gnus.el
index 89d5d12054,69f2bb2799..c411ec7deb
--- a/lisp/gnus/gnus.el
+++ b/lisp/gnus/gnus.el
@@@ -4126,12 -4140,11 +4140,12 @@@ prompt the user for the name of an NNT
    ;; file.
    (unless (string-match "^Gnus" gnus-version)
      (load "gnus-load" nil t))
 -  (unless (byte-code-function-p (symbol-function 'gnus))
 -    (message "You should byte-compile Gnus")
 +  (unless (or (byte-code-function-p (symbol-function 'gnus))
 +            (subr-native-elisp-p (symbol-function 'gnus)))
 +    (message "You should compile Gnus")
      (sit-for 2))
    (let ((gnus-action-message-log (list nil)))
-     (gnus-1 arg dont-connect slave)
+     (gnus-1 arg dont-connect child)
      (gnus-final-warning)))

  (declare-function debbugs-gnu "ext:debbugs-gnu"


In GNU Emacs 28.0.50 (build 1, x86_64-apple-darwin19.6.0, NS appkit-1894.60 
Version 10.15.6 (Build 19G73))
 of 2020-07-23 built on AllenDangMacBookPro.local
Repository revision: 37e0dbc97242a69da9f02039f5635261a307659a
Repository branch: feature/native-comp
Windowing system distributor 'Apple', version 10.3.1894
System Description:  Mac OS X 10.15.6

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Mark set
file-name-as-directory: Symbol’s value as variable is void: 
comp-native-path-postfix
Configured using:
 'configure LDFLAGS=-L/usr/local/lib/gcc/10'

Configured features:
JPEG TIFF GIF PNG RSVG GLIB NOTIFY KQUEUE ACL GNUTLS LIBXML2 ZLIB
TOOLKIT_SCROLL_BARS NS MODULES THREADS JSON PDUMPER LCMS2

Important settings:
  value of $LC_ALL: en_US.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 dired dired-loaddefs
rfc822 mml mml-sec password-cache epa epg epg-config gnus-util rmail
rmail-loaddefs text-property-search time-date mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils comp pcase
derived subr-x rx cl-seq cl-macs cl-extra help-mode easymenu seq
byte-opt gv cl-loaddefs cl-lib bytecomp byte-compile cconv tooltip eldoc
electric uniquify ediff-hook vc-hooks lisp-float-type mwheel term/ns-win
ns-win ucs-normalize mule-util term/common-win tool-bar dnd fontset
image regexp-opt fringe tabulated-list replace newcomment text-mode
elisp-mode lisp-mode prog-mode register page tab-bar menu-bar
rfn-eshadow isearch timer select scroll-bar mouse jit-lock font-lock
syntax facemenu font-core term/tty-colors frame minibuffer 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
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 threads kqueue cocoa ns
lcms2 multi-tty make-network-process emacs)

Memory information:
((conses 16 90836 8976)
 (symbols 48 8094 1)
 (strings 32 18835 1532)
 (string-bytes 1 625861)
 (vectors 16 11587)
 (vector-slots 8 138705 11517)
 (floats 8 23 17)
 (intervals 56 198 0)
 (buffers 992 10))