Merge from origin/emacs-26

0b810eb Fix a typo in char-width-table
3f00db7 Minor update in admin/notes/unicode
bcd0115 Fix lisp indent infloop on unfinished strings (Bug#37045)
5f992d1 Improve commentary in composite.el
3a04be2 ; Improve commentary in xdisp.c
15de1d1 Fix markup in dired-x.texi
bda7fc7 ; Fix typo in a doc string of speedbar.el
6f57ef9 * src/callproc.c (Fcall_process): Doc fix.

# Conflicts:
#	doc/misc/dired-x.texi
#	lisp/international/characters.el
#	src/callproc.c

1 files changed, 8 insertions, 1 deletions

diff --git a/lisp/composite.el b/lisp/composite.el
index e0d0721f16d..d0f20949438 100644
--- a/lisp/composite.el
+++ b/lisp/composite.el
@@ -555,6 +555,11 @@ All non-spacing characters have this function in
      ;; This sequence doesn't start with a proper base character.
      ((memq (get-char-code-property (lgstring-char gstring 0)
 				    'general-category)
+            ;; "Improper" base characters are of the following general
+            ;; categories:
+            ;;   Mark (nonspacing, combining, enclosing)
+            ;;   Separator (space, line, paragraph)
+            ;;   Other (control, format, surrogate)
 	    '(Mn Mc Me Zs Zl Zp Cc Cf Cs))
       nil)
 
@@ -647,6 +652,7 @@ All non-spacing characters have this function in
 			  de (+ de yoff)))
 		   ((and (= class 0)
 			 (eq (get-char-code-property (lglyph-char glyph)
+                                                     ;; Me = enclosing mark
 						     'general-category) 'Me))
 		    ;; Artificially laying out glyphs in an enclosing
 		    ;; mark is difficult.  All we can do is to adjust
@@ -772,7 +778,8 @@ prepending a space before it."
 					    'general-category)
 		    'Cf)
 		(progn
-		  ;; Compose by replacing with a space.
+		  ;; Compose Cf (format) control characters by
+		  ;; replacing with a space.
 		  (lglyph-set-char glyph 32)
 		  (lglyph-set-width glyph 1)
 		  (setq i (1+ i)))