bug#14427: 24.3.50; Highlight symbol at point

[Juri Linkov <juri@jurta.org>]

This feature request mostly doesn't depend on the outcome of bug#14405.
I don't know why Jambunathan didn't propose this feature earlier, but it
logically follows from his other improvements in hi-lock.el, i.e. the
feature that doesn't ask for a face and automatically uses the next face
from the list of available faces suggests also a command that doesn't ask
for a symbol and automatically uses the symbol at point:

=== modified file 'lisp/hi-lock.el'
--- lisp/hi-lock.el	2013-03-31 13:34:35 +0000
+++ lisp/hi-lock.el	2013-05-20 22:52:54 +0000
@@ -483,6 +461,27 @@ (defun hi-lock-face-phrase-buffer (regex
   (unless hi-lock-mode (hi-lock-mode 1))
   (hi-lock-set-pattern regexp face))
 
+;;;###autoload
+(defalias 'highlight-symbol-at-point 'hi-lock-face-symbol-at-point)
+;;;###autoload
+(defun hi-lock-face-symbol-at-point ()
+  "Set face of each match of the symbol at point.
+Use `find-tag-default-as-symbol-regexp' to retrieve the symbol at point.
+Use non-nil `hi-lock-auto-select-face' to retrieve the next face
+from `hi-lock-face-defaults' automatically.
+
+Use Font lock mode, if enabled, to highlight symbol at point.
+Otherwise, use overlays for highlighting.  If overlays are used,
+the highlighting will not update as you type."
+  (interactive)
+  (let* ((regexp (hi-lock-regexp-okay
+		  (find-tag-default-as-symbol-regexp)))
+	 (hi-lock-auto-select-face t)
+	 (face (hi-lock-read-face-name)))
+    (or (facep face) (setq face 'hi-yellow))
+    (unless hi-lock-mode (hi-lock-mode 1))
+    (hi-lock-set-pattern regexp face)))
+
 (defun hi-lock-keyword->face (keyword)
   (cadr (cadr (cadr keyword))))    ; Keyword looks like (REGEXP (0 'FACE) ...).