Fix 'current-column' in the presence of display strings

* src/indent.c (check_display_width): Support calculation of width
of 'display' properties whose values are strings.  This fixes the
value returned by 'current-column' when display strings are
present between BOL and point.  (Bug#53795)

1 files changed, 36 insertions, 25 deletions

diff --git a/src/indent.c b/src/indent.c
index 5c21cd8f99d..efeb9e74f43 100644
--- a/src/indent.c
+++ b/src/indent.c
@@ -468,31 +468,40 @@ check_display_width (ptrdiff_t pos, ptrdiff_t col, ptrdiff_t *endpos)
 {
   Lisp_Object val, overlay;
 
-  if (CONSP (val = get_char_property_and_overlay
-	     (make_fixnum (pos), Qdisplay, Qnil, &overlay))
-      && EQ (Qspace, XCAR (val)))
-    { /* FIXME: Use calc_pixel_width_or_height.  */
-      Lisp_Object plist = XCDR (val), prop;
+  if (!NILP (val = get_char_property_and_overlay (make_fixnum (pos), Qdisplay,
+						  Qnil, &overlay)))
+    {
       int width = -1;
-      EMACS_INT align_to_max =
-	(col < MOST_POSITIVE_FIXNUM - INT_MAX
-	 ? (EMACS_INT) INT_MAX + col
-	 : MOST_POSITIVE_FIXNUM);
-
-      if ((prop = Fplist_get (plist, QCwidth),
-	   RANGED_FIXNUMP (0, prop, INT_MAX))
-	  || (prop = Fplist_get (plist, QCrelative_width),
-	      RANGED_FIXNUMP (0, prop, INT_MAX)))
-	width = XFIXNUM (prop);
-      else if (FLOATP (prop) && 0 <= XFLOAT_DATA (prop)
-	       && XFLOAT_DATA (prop) <= INT_MAX)
-	width = (int)(XFLOAT_DATA (prop) + 0.5);
-      else if ((prop = Fplist_get (plist, QCalign_to),
-		RANGED_FIXNUMP (col, prop, align_to_max)))
-	width = XFIXNUM (prop) - col;
-      else if (FLOATP (prop) && col <= XFLOAT_DATA (prop)
-	       && (XFLOAT_DATA (prop) <= align_to_max))
-	width = (int)(XFLOAT_DATA (prop) + 0.5) - col;
+      Lisp_Object plist = Qnil;
+
+      /* Handle '(space ...)' display specs.  */
+      if (CONSP (val) && EQ (Qspace, XCAR (val)))
+	{ /* FIXME: Use calc_pixel_width_or_height.  */
+	  Lisp_Object prop;
+	  EMACS_INT align_to_max =
+	    (col < MOST_POSITIVE_FIXNUM - INT_MAX
+	     ? (EMACS_INT) INT_MAX + col
+	     : MOST_POSITIVE_FIXNUM);
+
+	  plist = XCDR (val);
+	  if ((prop = Fplist_get (plist, QCwidth),
+	       RANGED_FIXNUMP (0, prop, INT_MAX))
+	      || (prop = Fplist_get (plist, QCrelative_width),
+		  RANGED_FIXNUMP (0, prop, INT_MAX)))
+	    width = XFIXNUM (prop);
+	  else if (FLOATP (prop) && 0 <= XFLOAT_DATA (prop)
+		   && XFLOAT_DATA (prop) <= INT_MAX)
+	    width = (int)(XFLOAT_DATA (prop) + 0.5);
+	  else if ((prop = Fplist_get (plist, QCalign_to),
+		    RANGED_FIXNUMP (col, prop, align_to_max)))
+	    width = XFIXNUM (prop) - col;
+	  else if (FLOATP (prop) && col <= XFLOAT_DATA (prop)
+		   && (XFLOAT_DATA (prop) <= align_to_max))
+	    width = (int)(XFLOAT_DATA (prop) + 0.5) - col;
+	}
+      /* Handle 'display' strings.   */
+      else if (STRINGP (val))
+	width = XFIXNUM (Fstring_width (val, Qnil, Qnil));
 
       if (width >= 0)
 	{
@@ -504,7 +513,8 @@ check_display_width (ptrdiff_t pos, ptrdiff_t col, ptrdiff_t *endpos)
 
 	  /* For :relative-width, we need to multiply by the column
 	     width of the character at POS, if it is greater than 1.  */
-	  if (!NILP (Fplist_get (plist, QCrelative_width))
+	  if (!NILP (plist)
+	      && !NILP (Fplist_get (plist, QCrelative_width))
 	      && !NILP (BVAR (current_buffer, enable_multibyte_characters)))
 	    {
 	      int b, wd;
@@ -516,6 +526,7 @@ check_display_width (ptrdiff_t pos, ptrdiff_t col, ptrdiff_t *endpos)
 	  return width;
 	}
     }
+
   return -1;
 }