Merge from origin/emacs-27

ac1a2b2160 Add more doc-view requirements
109eb1e7e2 Fix undefined behavior when fetching glyphs from the displ...

# Conflicts:
#	lisp/doc-view.el

2 files changed, 9 insertions, 7 deletions

diff --git a/lisp/doc-view.el b/lisp/doc-view.el
index 73483b25796..9997c1ae7b8 100644
--- a/lisp/doc-view.el
+++ b/lisp/doc-view.el
@@ -22,10 +22,12 @@
 
 ;;; Requirements:
 
-;; doc-view.el requires GNU Emacs 22.1 or newer.  You also need Ghostscript,
-;; `dvipdf' (comes with Ghostscript) or `dvipdfm' (comes with teTeX or TeXLive)
-;; and `pdftotext', which comes with xpdf (https://www.foolabs.com/xpdf/) or
-;; poppler (https://poppler.freedesktop.org/).
+;; Viewing PS/PDF/DVI files requires Ghostscript, `dvipdf' (comes with
+;; Ghostscript) or `dvipdfm' (comes with teTeX or TeXLive) and
+;; `pdftotext', which comes with xpdf (https://www.foolabs.com/xpdf/)
+;; or poppler (https://poppler.freedesktop.org/).
+;; Djvu documents require `ddjvu' (from DjVuLibre).
+;; ODF files require `soffice' (from LibreOffice).
 
 ;;; Commentary:
 
diff --git a/src/xdisp.c b/src/xdisp.c
index 32486eaa37b..2344fe70601 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -8324,10 +8324,10 @@ next_element_from_display_vector (struct it *it)
 	    next_face_id = it->dpvec_face_id;
 	  else
 	    {
-	      int lface_id =
-		GLYPH_CODE_FACE (it->dpvec[it->current.dpvec_index + 1]);
+              Lisp_Object gc = it->dpvec[it->current.dpvec_index + 1];
+              int lface_id = GLYPH_CODE_P (gc) ? GLYPH_CODE_FACE (gc) : 0;
 
-	      if (lface_id > 0)
+              if (lface_id > 0)
 		next_face_id = merge_faces (it->w, Qt, lface_id,
 					    it->saved_face_id);
 	    }