bug#49797: 28.0.50; Setting face to custom fontset doesn't work

[Yuan Fu]

If I evaluate the following:

(progn
  (create-fontset-from-fontset-spec
   (font-xlfd-name
    (font-spec :registry "fontset-lunamono")))
  (set-fontset-font "fontset-lunamono" 'latin (font-spec :family "SF Mono"))
  (set-face-attribute 'default nil :fontset "fontset-lunamono”))

I expect Latin characters to be shown in SF Mono font, but that’s not what 
happened. If I instead set font for the default fontset, the characters in the 
buffer are correctly displayed in SF Mono font. I tried this code snippet with 
Emacs 26, 27 and 28, and all of them have this problem.

I can see that the fondest is correctly modified by looking at the result of 
describe-fontset, so I guess it’s the face that isn’t finding the correct font 
to display the character.

Yuan

In GNU Emacs 28.0.50 (build 72, x86_64-apple-darwin20.3.0, NS appkit-2022.30 
Version 11.2.3 (Build 20D91))
of 2021-07-31 built on Brown
Repository revision: dd34bef7d3769a8574bcee2c1e91e8445129af75
Repository branch: master
Windowing system distributor 'Apple', version 10.3.2022
System Description:  macOS 11.2.3

Configured using:
'configure --with-pdumper=yes --with-ns --enable-checking=yes,glyphs
--enable-check-lisp-object-type 'CFLAGS=-O0 -g3''

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

Important settings:
  value of $LC_CTYPE: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-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
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: 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 epa derived epg epg-config gnus-util rmail
rmail-loaddefs auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json map text-property-search time-date
subr-x seq byte-opt gv bytecomp byte-compile cconv mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader cl-loaddefs
cl-lib sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr mail-utils
iso-transl 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 easymenu
timer select scroll-bar mouse jit-lock font-lock syntax 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 button
loaddefs faces cus-face macroexp files window 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 51166 10427)
(symbols 48 6528 1)
(strings 32 17706 1638)
(string-bytes 1 583355)
(vectors 16 13503)
(vector-slots 8 175734 10173)
(floats 8 21 47)
(intervals 56 190 0)
(buffers 992 11))