(Fdelete_and_extract_region): Use empty_unibyte_string.

src/ChangeLog

+2007-06-08  Juanma Barranquero	<lekktu@gmail.com>
+
+	* callint.c (Fcall_interactively):
+	* editfns.c (Fdelete_and_extract_region):
+	* fileio.c (Fread_file_name):
+	* fns.c (Fmapconcat):
+	* keyboard.c (cmd_error_internal):
+	* keymap.c (Fkey_description):
+	* lread.c (openp):
+	* minibuf.c (read_minibuf):
+	* search.c (wordify):
+	* sunfns.c (sel_read):
+	* xdisp.c (Fformat_mode_line, syms_of_xdisp):
+	* xfns.c (x_default_scroll_bar_color_parameter):
+	* xmenu.c (menu_help_callback):
+	* xselect.c (Fx_get_atom_name):
+	* xterm.c (x_term_init): Use empty_unibyte_string.
+
+2007-06-08  Dmitry Antipov  <dmitry.antipov@mail.ru>  (tiny change)
+
+	* alloc.c (init_strings): Initialize canonical empty strings.
+	(make_uninit_string, make_uninit_multibyte_string): Return appropriate
+	canonical empty string when the requested size is 0.
+
+	* emacs.c (empty_unibyte_string): Rename from empty_string.
+	(empty_multibyte_string): New canonical empty string.
+	(syms_of_emacs): Don't initialize empty_string.
+
+	* lisp.h (STRING_SET_UNIBYTE): Return the canonical empty unibyte
+	string, if appropriate.
+	(empty_unibyte_string, empty_multibyte_string): New externs.
+	(empty_string): Remove extern.
+
+	* lread.c (syms_of_lread): Use empty_unibyte_string.
+
 2007-06-07  Jason Rumney  <jasonr@gnu.org>
 
 	* s/ms-w32.h: Don't define HAVE_TZNAME.

src/callint.c

@@ -585,7 +585,7 @@ invoke it.  If KEYS is omitted or nil, the return value of
 	case 'G':		/* Possibly nonexistent file name,
 				   default to directory alone. */
 	  args[i] = Fread_file_name (callint_message,
-				     Qnil, Qnil, Qnil, build_string (""), Qnil);
+				     Qnil, Qnil, Qnil, empty_unibyte_string, Qnil);
 	  break;
 
 	case 'i':		/* Ignore an argument -- Does not do I/O */

src/editfns.c

@@ -3031,7 +3031,7 @@ DEFUN ("delete-and-extract-region", Fdelete_and_extract_region,
 {
   validate_region (&start, &end);
   if (XINT (start) == XINT (end))
-    return build_string ("");
+    return empty_unibyte_string;
   return del_range_1 (XINT (start), XINT (end), 1, 1);
 }