bug#33682: 27.0.50; enriched-mode cannot save anonymous faces

[Charles A. Roelli]

C-x C-f /tmp/test-file
M-x enriched-mode RET
M-: (insert (propertize "foo" 'face '(:background "red"))) RET
C-x C-s

Error: Invalid face: :background

The backtrace is:
Debugger entered--Lisp error: (error "Invalid face" :background)
  internal-get-lisp-face-attribute(:background :foreground nil)
  face-attribute(:background :foreground)
  enriched-face-ans(:background)
  enriched-encode-other-face(nil :background)
  format-annotate-atomic-property-change(((bold-italic "bold" "italic") (bold 
"bold") (italic "italic") (underline "underline") (fixed "fixed") (excerpt 
"excerpt") (default) (nil enriched-encode-other-face)) nil :background)
  format-annotate-single-property-change(face nil (:background "red") ((face 
(bold-italic "bold" "italic") (bold "bold") (italic "italic") (underline 
"underline") (fixed "fixed") (excerpt "excerpt") (default) (nil 
enriched-encode-other-face)) (left-margin (4 "indent")) (right-margin (4 
"indentright")) (justification (none "nofill") (right "flushright") (left 
"flushleft") (full "flushboth") (center "center")) (PARAMETER (t "param")) 
(FUNCTION (enriched-decode-foreground "x-color") (enriched-decode-background 
"x-bg-color") (enriched-decode-display-prop "x-display") 
(enriched-decode-charset "x-charset")) (read-only (t "x-read-only")) (display 
(nil enriched-handle-display-prop)) (charset (nil 
enriched-handle-charset-prop)) (unknown (nil format-annotate-value))))
  format-annotate-location(1 t (front-sticky rear-nonsticky hard) ((face 
(bold-italic "bold" "italic") (bold "bold") (italic "italic") (underline 
"underline") (fixed "fixed") (excerpt "excerpt") (default) (nil 
enriched-encode-other-face)) (left-margin (4 "indent")) (right-margin (4 
"indentright")) (justification (none "nofill") (right "flushright") (left 
"flushleft") (full "flushboth") (center "center")) (PARAMETER (t "param")) 
(FUNCTION (enriched-decode-foreground "x-color") (enriched-decode-background 
"x-bg-color") (enriched-decode-display-prop "x-display") 
(enriched-decode-charset "x-charset")) (read-only (t "x-read-only")) (display 
(nil enriched-handle-display-prop)) (charset (nil 
enriched-handle-charset-prop)) (unknown (nil format-annotate-value))))
  format-annotate-region(1 4 ((face (bold-italic "bold" "italic") (bold "bold") 
(italic "italic") (underline "underline") (fixed "fixed") (excerpt "excerpt") 
(default) (nil enriched-encode-other-face)) (left-margin (4 "indent")) 
(right-margin (4 "indentright")) (justification (none "nofill") (right 
"flushright") (left "flushleft") (full "flushboth") (center "center")) 
(PARAMETER (t "param")) (FUNCTION (enriched-decode-foreground "x-color") 
(enriched-decode-background "x-bg-color") (enriched-decode-display-prop 
"x-display") (enriched-decode-charset "x-charset")) (read-only (t 
"x-read-only")) (display (nil enriched-handle-display-prop)) (charset (nil 
enriched-handle-charset-prop)) (unknown (nil format-annotate-value))) 
enriched-make-annotation (front-sticky rear-nonsticky hard))
  enriched-encode(1 4 #<buffer test-file-3>)
  format-encode-run-method(enriched-encode 1 4 #<buffer test-file-3>)
  format-annotate-function(text/enriched nil nil #<buffer test-file-3> 0)
  write-region(nil nil "/tmp/test-file-3" nil t "/private/tmp/test-file-3")
  basic-save-buffer-2()
  basic-save-buffer-1()
  basic-save-buffer(t)
  save-buffer(1)
  funcall-interactively(save-buffer 1)
  call-interactively(save-buffer nil nil)
  command-execute(save-buffer)


In GNU Emacs 27.0.50 (build 8, x86_64-apple-darwin10.8.0, NS appkit-1038.36 
Version 10.6.8 (Build 10K549))
 of 2018-12-09 built on gray
Repository revision: d79bb75683ceb4eee2f753eb38fa8db99aff4568
Repository branch: master
Windowing system distributor 'Apple', version 10.3.1038
System Description:  Mac OS X 10.6.8