master 4243747b1b: Fix 'current-column' in the presence of display strings

[Eli Zaretskii]

branch: master
commit 4243747b1b8c3b7e3463822804b32e83febe2878
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    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)
---
 src/indent.c | 61 +++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 36 insertions(+), 25 deletions(-)

diff --git a/src/indent.c b/src/indent.c
index 5c21cd8f99..efeb9e74f4 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;
 }