bug#45342: 28.0.50; Native compiled function returns raw bytes, not string

[Alexander Miller]

In my config I have the following function that is used to prettify my
mode-line (the actual version is pure and side-effect-free and inlined,
but that does not seem to have any effect here):

(defun f (n)
  (pcase n
    (1 " ➊") (2 " ➋") (3 " ➌") (4 " ➍") (5 " ➎") (6 " ➏")
    (7 " ➐") (8 " ➑") (9 " ➒") (10 " ➓") (_ "")))

When native compiled it appears to return raw bytes instead of the
unicode symbols, for example I am seeing \342\236\212 instead of ➊.

I can circumvent that by using (1 (decode-coding-string " ➊" 'utf-8)),
but of course that should not be necessary, since there's no such
problem with the byte-compiled version.

And on a probably unrelated note: is it normal for such a simple
function to be compiled to 100 LOC of assembly? That seems surprisingly
to my amateur eyes.

In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version
3.24.23, cairo version 1.17.3)
of 2020-12-20 built on am-laptop
Repository revision: ab985f41db5fdaeada513d28a065332fd8838cf4
Repository branch: makepkg
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Manjaro Linux

Configured using:
'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
--localstatedir=/var --mandir=/usr/share/man --with-gameuser=:games
--with-sound=alsa --with-modules --without-gconf --without-gsettings
--with-nativecomp --with-x-toolkit=gtk3 --without-xaw3d
--without-m17n-flt --with-cairo --without-compress-install
'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt -g
-fuse-ld=gold' CPPFLAGS=-D_FORTIFY_SOURCE=2
LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

Configured features:
XPM JPEG TIFF GIF PNG RSVG CAIRO SOUND GPM DBUS GLIB NOTIFY INOTIFY ACL
GNUTLS LIBXML2 FREETYPE HARFBUZZ LIBOTF ZLIB TOOLKIT_SCROLL_BARS GTK3
X11 XDBE XIM MODULES NATIVE_COMP THREADS LIBSYSTEMD JSON PDUMPER LCMS2

Important settings:
value of $LC_MONETARY: de_DE.UTF-8
value of $LC_NUMERIC: de_DE.UTF-8
value of $LC_TIME: de_DE.UTF-8
value of $LANG: en_GB.utf8
locale-coding-system: utf-8

Major mode: ELisp/l

Minor modes in effect:
rainbow-delimiters-mode: t
rainbow-mode: t
display-line-numbers-mode: t
hl-todo-mode: t
org-super-agenda-mode: t
treemacs-icons-dired-mode: t
treemacs-filewatch-mode: t
treemacs-follow-mode: t
treemacs-git-mode: deferred
treemacs-fringe-indicator-mode: t
helm-mode: t
helm--remap-mouse-mode: t
async-bytecomp-package-mode: t
gcmh-mode: t
projectile-mode: t
company-prescient-mode: t
global-company-mode: t
company-mode: t
global-evil-vimish-fold-mode: t
evil-vimish-fold-mode: t
vimish-fold-mode: t
show-smartparens-global-mode: t
show-smartparens-mode: t
smartparens-global-mode: t
smartparens-mode: t
framey-mode: t
purpose-mode: t
shackle-mode: t
winum-mode: t
eyebrowse-mode: t
global-subword-mode: t
subword-mode: t
global-evil-surround-mode: t
evil-surround-mode: t
evil-lion-mode: t
evil-goggles-mode: t
shell-dirtrack-mode: t
evil-mode: t
evil-local-mode: t
tooltip-mode: t
global-eldoc-mode: t
eldoc-mode: t
electric-indent-mode: t
mouse-wheel-mode: t
tool-bar-mode: t
prettify-symbols-mode: t
menu-bar-mode: t
file-name-shadow-mode: t
global-font-lock-mode: t
font-lock-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:
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/home/am/.emacs.d/straight/build/let-alist/let-alist
~/Documents/git/treemacs/src/elisp/treemacs-interface hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-interface
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/home/am/.emacs.d/straight/build/treemacs/treemacs-rendering
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/home/am/.emacs.d/straight/build/treemacs/treemacs
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/home/am/.emacs.d/straight/build/treemacs/treemacs-workspaces
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/home/am/.emacs.d/straight/build/treemacs/treemacs-customization
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/home/am/.emacs.d/straight/build/treemacs/treemacs-faces
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/home/am/.emacs.d/straight/build/treemacs/treemacs-themes
~/Documents/git/treemacs/src/elisp/treemacs-mouse-interface hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-mouse-interface
~/Documents/git/treemacs/src/elisp/treemacs-mode hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-mode
~/Documents/git/treemacs/src/elisp/treemacs-icons hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-icons
~/Documents/git/treemacs/src/elisp/treemacs-compatibility hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-compatibility
~/Documents/git/treemacs/src/elisp/treemacs-follow-mode hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-follow-mode
~/Documents/git/treemacs/src/elisp/treemacs-visuals hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-visuals
~/Documents/git/treemacs/src/elisp/treemacs-core-utils hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-core-utils
~/Documents/git/treemacs/src/elisp/treemacs-extensions hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-extensions
~/Documents/git/treemacs/src/elisp/treemacs-filewatch-mode hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-filewatch-mode
~/Documents/git/treemacs/src/elisp/treemacs-persistence hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-persistence
~/Documents/git/treemacs/src/elisp/treemacs-async hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-async
~/Documents/git/treemacs/src/elisp/treemacs-bookmarks hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-bookmarks
~/Documents/git/treemacs/src/elisp/treemacs-tag-follow-mode hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-tag-follow-mode
~/Documents/git/treemacs/src/elisp/treemacs-logging hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-logging
~/Documents/git/treemacs/src/elisp/treemacs-header-line hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-header-line
~/Documents/git/treemacs/src/elisp/treemacs-fringe-indicator hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-fringe-indicator
~/Documents/git/treemacs/src/elisp/treemacs-diagnostics hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-diagnostics
~/Documents/git/treemacs/src/elisp/treemacs-macros hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-macros
~/Documents/git/treemacs/src/elisp/treemacs-scope hides
/home/am/.emacs.d/straight/build/treemacs/treemacs-scope

Features:
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Memory information:
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