5 files changed, 91 insertions, 19 deletions

diff --git a/lisp/cus-face.el b/lisp/cus-face.el
index d73bce42c3e..5a49a810434 100644
--- a/lisp/cus-face.el
+++ b/lisp/cus-face.el
@@ -233,7 +233,11 @@
              (file :tag "File"
                    :help-echo "Name of bitmap file."
                    :must-match t)))
-
+    (:extend
+     (choice :tag "Extend"
+             :help-echo "Control whether attributes should be extended after EOL."
+             (const :tag "Off" nil)
+             (const :tag "On" t)))
     (:inherit
      (repeat :tag "Inherit"
              :help-echo "List of faces to inherit attributes from."
diff --git a/lisp/faces.el b/lisp/faces.el
index c789d3729e0..36fc69895dd 100644
--- a/lisp/faces.el
+++ b/lisp/faces.el
@@ -342,6 +342,7 @@ is either `foreground-color', `background-color', or a keyword."
     (:box (".attributeBox" . "Face.AttributeBox"))
     (:underline (".attributeUnderline" . "Face.AttributeUnderline"))
     (:inverse-video (".attributeInverse" . "Face.AttributeInverse"))
+    (:extend (".attributeExtend" . "Face.AttributeExtend"))
     (:stipple
      (".attributeStipple" . "Face.AttributeStipple")
      (".attributeBackgroundPixmap" . "Face.AttributeBackgroundPixmap"))
@@ -594,6 +595,13 @@ Use `face-attribute' for finer control."
   (let ((italic (face-attribute face :slant frame inherit)))
     (memq italic '(italic oblique))))
 
+(defun face-extend-p (face &optional frame inherit)
+ "Return non-nil if FACE specifies a non-nil extend.
+If the optional argument FRAME is given, report on face FACE in that frame.
+If FRAME is t, report on the defaults for face FACE (for new frames).
+If FRAME is omitted or nil, use the selected frame.
+Optional argument INHERIT is passed to `face-attribute'."
+ (eq (face-attribute face :extend frame inherit) t))
 
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -760,6 +768,11 @@ For convenience, attributes `:family', `:foundry', `:width',
 `:height', `:weight', and `:slant' may also be set in one step
 from an X font name:
 
+`:extend'
+
+VALUE specifies whether the FACE should be extended after EOL.
+VALUE must be one of t or nil.
+
 `:font'
 
 Set font-related face attributes from VALUE.
@@ -979,6 +992,18 @@ Use `set-face-attribute' or `modify-face' for finer control."
 
 (define-obsolete-function-alias 'set-face-italic-p 'set-face-italic "24.4")
 
+(defun set-face-extend (face extend-p &optional frame)
+  "Specify whether face FACE should be extended.
+EXTEND-P nil means FACE explicitly doesn't extend after EOL.
+EXTEND-P t means FACE extends after EOL.
+
+FRAME nil or not specified means change face on all frames.
+Use `set-face-attribute' to \"unspecify\" underlining."
+  (interactive
+   (let ((list (read-face-and-attribute :extend)))
+     (list (car list) (if (cadr list) t))))
+  (set-face-attribute face frame :extend extend-p))
+
 
 (defalias 'set-face-background-pixmap 'set-face-stipple)
 
@@ -1102,7 +1127,7 @@ an integer value."
            (:slant
             (mapcar #'(lambda (x) (cons (symbol-name (aref x 1)) (aref x 1)))
                     font-slant-table))
-           (:inverse-video
+           ((or :inverse-video :extend)
             (mapcar #'(lambda (x) (cons (symbol-name x) x))
                     (internal-lisp-face-attribute-values attribute)))
            ((or :underline :overline :strike-through :box)
@@ -1147,6 +1172,7 @@ an integer value."
     (:slant . "slant")
     (:underline . "underline")
     (:overline . "overline")
+    (:extend . "extend")
     (:strike-through . "strike-through")
     (:box . "box")
     (:inverse-video . "inverse-video display")
@@ -1549,7 +1575,8 @@ is given, in which case return its value instead."
              ;; (see also realize_default_face in xfaces.c).
              (append
               '(:underline nil :overline nil :strike-through nil
-                :box nil :inverse-video nil :stipple nil :inherit nil)
+                :box nil :inverse-video nil :stipple nil :inherit nil
+                :extend nil)
               ;; `display-graphic-p' is unavailable when running
               ;; temacs, prior to loading frame.el.
               (when (fboundp 'display-graphic-p)
@@ -2314,24 +2341,24 @@ If you set `term-file-prefix' to nil, this function does nothing."
 ;; if background is light.
 (defface region
   '((((class color) (min-colors 88) (background dark))
-     :background "blue3")
+     :background "blue3" :extend t)
     (((class color) (min-colors 88) (background light) (type gtk))
      :distant-foreground "gtk_selection_fg_color"
-     :background "gtk_selection_bg_color")
+     :background "gtk_selection_bg_color" :extend t)
     (((class color) (min-colors 88) (background light) (type ns))
      :distant-foreground "ns_selection_fg_color"
-     :background "ns_selection_bg_color")
+     :background "ns_selection_bg_color" :extend t)
     (((class color) (min-colors 88) (background light))
-     :background "lightgoldenrod2")
+     :background "lightgoldenrod2" :extend t)
     (((class color) (min-colors 16) (background dark))
-     :background "blue3")
+     :background "blue3" :extend t)
     (((class color) (min-colors 16) (background light))
-     :background "lightgoldenrod2")
+     :background "lightgoldenrod2" :extend t)
     (((class color) (min-colors 8))
-     :background "blue" :foreground "white")
+     :background "blue" :foreground "white" :extend t)
     (((type tty) (class mono))
      :inverse-video t)
-    (t :background "gray"))
+    (t :background "gray" :extend t))
   "Basic face for highlighting the region."
   :version "21.1"
   :group 'basic-faces)
diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index 5e55240daba..235aa9a6e19 100644
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -1385,6 +1385,7 @@ If FRAME is omitted or nil, use the selected frame."
                   (:stipple . "Stipple")
                   (:font . "Font")
                   (:fontset . "Fontset")
+                  (:extend . "Extend")
                   (:inherit . "Inherit")))
          (max-width (apply #'max (mapcar #'(lambda (x) (length (cdr x)))
                                          attrs))))
diff --git a/src/dispextern.h b/src/dispextern.h
index 57400ae047a..519cc36345c 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1677,11 +1677,9 @@ struct face
   /* Pixel value or color index of background color.  */
   unsigned long background;
 
-  /* Pixel value or color index of underline color.  */
+  /* Pixel value or color index of underline, overlined,
+     strike-through, or box color.  */
   unsigned long underline_color;
-
-  /* Pixel value or color index of overlined, strike-through, or box
-     color.  */
   unsigned long overline_color;
   unsigned long strike_through_color;
   unsigned long box_color;
@@ -1864,6 +1862,9 @@ struct face_cache
    ? FRAME_FACE_CACHE (F)->faces_by_id[ID]              \
    : NULL)
 
+#define FACE_EXTENSIBLE_P(F)                    \
+  (!NILP (F->lface[LFACE_EXTEND_INDEX]))
+
 /* True if FACE is suitable for displaying ASCII characters.  */
 INLINE bool
 FACE_SUITABLE_FOR_ASCII_CHAR_P (struct face *face)
@@ -2373,7 +2374,7 @@ struct it
   /* Face id of the iterator saved in case a glyph from dpvec contains
      a face.  The face is restored when all glyphs from dpvec have
      been delivered.  */
-  int saved_face_id;
+  int saved_face_id, saved_extend_face_id;
 
   /* Vector of glyphs for control character translation.  The pointer
      dpvec is set to ctl_chars when a control character is translated.
@@ -2435,7 +2436,7 @@ struct it
     ptrdiff_t prev_stop;
     ptrdiff_t base_level_stop;
     struct composition_it cmp_it;
-    int face_id;
+    int face_id, extend_face_id;
 
     /* Save values specific to a given method.  */
     union {
@@ -2493,6 +2494,9 @@ struct it
   /* Face to use.  */
   int face_id;
 
+  /* Face to extend at EOL/  */
+  int extend_face_id;
+
   /* Setting of buffer-local variable selective-display-ellipses.  */
   bool_bf selective_display_ellipsis_p : 1;
 
diff --git a/src/xfaces.c b/src/xfaces.c
index c7d6990f505..889bf83561c 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -1590,6 +1590,7 @@ the WIDTH times as wide as FACE on FRAME.  */)
 #define LFACE_FONT(LFACE)           AREF ((LFACE), LFACE_FONT_INDEX)
 #define LFACE_INHERIT(LFACE)        AREF ((LFACE), LFACE_INHERIT_INDEX)
 #define LFACE_FONTSET(LFACE)        AREF ((LFACE), LFACE_FONTSET_INDEX)
+#define LFACE_EXTEND(LFACE)         AREF ((LFACE), LFACE_EXTEND_INDEX)
 #define LFACE_DISTANT_FOREGROUND(LFACE) \
   AREF ((LFACE), LFACE_DISTANT_FOREGROUND_INDEX)
 
@@ -1633,6 +1634,10 @@ check_lface_attrs (Lisp_Object attrs[LFACE_VECTOR_SIZE])
            || SYMBOLP (attrs[LFACE_UNDERLINE_INDEX])
            || STRINGP (attrs[LFACE_UNDERLINE_INDEX])
            || CONSP (attrs[LFACE_UNDERLINE_INDEX]));
+  eassert (UNSPECIFIEDP (attrs[LFACE_EXTEND_INDEX])
+           || IGNORE_DEFFACE_P (attrs[LFACE_EXTEND_INDEX])
+           || SYMBOLP (attrs[LFACE_EXTEND_INDEX])
+           || STRINGP (attrs[LFACE_EXTEND_INDEX]));
   eassert (UNSPECIFIEDP (attrs[LFACE_OVERLINE_INDEX])
            || IGNORE_DEFFACE_P (attrs[LFACE_OVERLINE_INDEX])
            || SYMBOLP (attrs[LFACE_OVERLINE_INDEX])
@@ -2512,6 +2517,13 @@ merge_face_ref (struct window *w,
                                         err_msgs, named_merge_points))
                     err = true;
                 }
+              else if (EQ (keyword, QCextend))
+                {
+                  if (EQ (value, Qt) || NILP (value))
+                    to[LFACE_EXTEND_INDEX] = value;
+                  else
+                    err = true;
+                }
               else
                 err = true;
 
@@ -3030,6 +3042,17 @@ FRAME 0 means change the face on all frames, and change the default
       old_value = LFACE_INVERSE (lface);
       ASET (lface, LFACE_INVERSE_INDEX, value);
     }
+  else if (EQ (attr, QCextend))
+    {
+      if (!UNSPECIFIEDP (value) && !IGNORE_DEFFACE_P (value))
+        {
+          CHECK_SYMBOL (value);
+          if (!EQ (value, Qt) && !NILP (value))
+            signal_error ("Invalid extend face attribute value", value);
+        }
+      old_value = LFACE_EXTEND (lface);
+      ASET (lface, LFACE_EXTEND_INDEX, value);
+    }
   else if (EQ (attr, QCforeground))
     {
       /* Compatibility with 20.x.  */
@@ -3503,7 +3526,9 @@ DEFUN ("internal-set-lisp-face-attribute-from-resource",
     value = face_boolean_x_resource_value (value, true);
   else if (EQ (attr, QCweight) || EQ (attr, QCslant) || EQ (attr, QCwidth))
     value = intern (SSDATA (value));
-  else if (EQ (attr, QCreverse_video) || EQ (attr, QCinverse_video))
+  else if (EQ (attr, QCreverse_video)
+           || EQ (attr, QCinverse_video)
+           || EQ (attr, QCextend))
     value = face_boolean_x_resource_value (value, true);
   else if (EQ (attr, QCunderline)
            || EQ (attr, QCoverline)
@@ -3727,6 +3752,8 @@ frames).  If FRAME is omitted or nil, use the selected frame.  */)
     value = LFACE_SWIDTH (lface);
   else if (EQ (keyword, QCinherit))
     value = LFACE_INHERIT (lface);
+  else if (EQ (keyword, QCextend))
+    value = LFACE_EXTEND (lface);
   else if (EQ (keyword, QCfont))
     value = LFACE_FONT (lface);
   else if (EQ (keyword, QCfontset))
@@ -3754,7 +3781,9 @@ Value is nil if ATTR doesn't have a discrete set of valid values.  */)
 
   if (EQ (attr, QCunderline) || EQ (attr, QCoverline)
       || EQ (attr, QCstrike_through)
-      || EQ (attr, QCinverse_video) || EQ (attr, QCreverse_video))
+      || EQ (attr, QCinverse_video)
+      || EQ (attr, QCreverse_video)
+      || EQ (attr, QCextend))
     result = list2 (Qt, Qnil);
 
   return result;
@@ -4784,6 +4813,9 @@ gui_supports_face_attributes_p (struct frame *f,
       || (!UNSPECIFIEDP (attrs[LFACE_INVERSE_INDEX])
           && face_attr_equal_p (attrs[LFACE_INVERSE_INDEX],
                                 def_attrs[LFACE_INVERSE_INDEX]))
+      || (!UNSPECIFIEDP (attrs[LFACE_EXTEND_INDEX])
+          && face_attr_equal_p (attrs[LFACE_EXTEND_INDEX],
+                                def_attrs[LFACE_EXTEND_INDEX]))
       || (!UNSPECIFIEDP (attrs[LFACE_FOREGROUND_INDEX])
           && face_attr_equal_p (attrs[LFACE_FOREGROUND_INDEX],
                                 def_attrs[LFACE_FOREGROUND_INDEX]))
@@ -5362,6 +5394,9 @@ realize_default_face (struct frame *f)
         ASET (lface, LFACE_FONTSET_INDEX, Qnil);
     }
 
+  if (UNSPECIFIEDP (LFACE_EXTEND (lface)))
+    ASET (lface, LFACE_EXTEND_INDEX, Qnil);
+
   if (UNSPECIFIEDP (LFACE_UNDERLINE (lface)))
     ASET (lface, LFACE_UNDERLINE_INDEX, Qnil);
 
@@ -6539,6 +6574,7 @@ syms_of_xfaces (void)
   DEFSYM (QCstrike_through, ":strike-through");
   DEFSYM (QCbox, ":box");
   DEFSYM (QCinherit, ":inherit");
+  DEFSYM (QCextend, ":extend");
 
   /* Symbols used for Lisp face attribute values.  */
   DEFSYM (QCcolor, ":color");