* lisp/replace.el (query-replace-from-to-separator): Turn defvar into defcustom.

Wrap char-displayable-p in ignore-errors because an attempt
to autoload char-displayable-p fails during pre-loading.
Move (propertize "\0" ... 'separator t) out of customizable part
to query-replace-read-from.
(query-replace-read-from): Call custom-reevaluate-setting on
query-replace-from-to-separator to reevaluate the separator
depending on the return value of char-displayable-p.
http://lists.gnu.org/archive/html/emacs-devel/2014-11/msg00466.html

2 files changed, 32 insertions, 9 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 6a6ff73b365..ba01694c5dd 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,17 @@
 2014-11-18  Juri Linkov  <juri@linkov.net>
 
+        * replace.el (query-replace-from-to-separator): Turn defvar into
+        defcustom.  Wrap char-displayable-p in ignore-errors because an
+        attempt to autoload char-displayable-p fails during pre-loading.
+        Move (propertize "\0" ... 'separator t) out of customizable part
+        to query-replace-read-from.
+        (query-replace-read-from): Call custom-reevaluate-setting on
+        query-replace-from-to-separator to reevaluate the separator
+        depending on the return value of char-displayable-p.
+        http://lists.gnu.org/archive/html/emacs-devel/2014-11/msg00466.html
+
+2014-11-18  Juri Linkov  <juri@linkov.net>
+
         * bindings.el (minibuffer-local-map): Rebind [down] from
         next-history-element to next-line-or-history-element, and [up]
         from previous-history-element to previous-line-or-history-element.
diff --git a/lisp/replace.el b/lisp/replace.el
index c7fbcb5d99c..2c7ad19ea3b 100644
--- a/lisp/replace.el
+++ b/lisp/replace.el
@@ -67,11 +67,16 @@ That becomes the \"string to replace\".")
 to the minibuffer that reads the string to replace, or invoke replacements
 from Isearch by using a key sequence like `C-s C-s M-%'." "24.3")
 
-(defvar query-replace-from-to-separator
-  (propertize "\0"
-              'display (propertize " \u2192 " 'face 'minibuffer-prompt)
-              'separator t)
-  "String that separates FROM and TO in the history of replacement pairs.")
+(defcustom query-replace-from-to-separator
+  (propertize
+   (or (ignore-errors
+         (if (char-displayable-p ?\u2192) " \u2192 " " -> "))
+       " -> ")
+   'face 'minibuffer-prompt)
+  "String that separates FROM and TO in the history of replacement pairs."
+  :group 'matching
+  :type 'sexp
+  :version "25.1")
 
 (defcustom query-replace-from-history-variable 'query-replace-history
   "History list to use for the FROM argument of `query-replace' commands.
@@ -137,19 +142,25 @@ The return value can also be a pair (FROM . TO) indicating that the user
 wants to replace FROM with TO."
   (if query-replace-interactive
       (car (if regexp-flag regexp-search-ring search-ring))
+    (custom-reevaluate-setting 'query-replace-from-to-separator)
     (let* ((history-add-new-input nil)
+           (separator
+            (when query-replace-from-to-separator
+              (propertize "\0"
+                          'display query-replace-from-to-separator
+                          'separator t)))
            (query-replace-from-to-history
             (append
-             (when query-replace-from-to-separator
+             (when separator
                (mapcar (lambda (from-to)
                          (concat (query-replace-descr (car from-to))
-                                 query-replace-from-to-separator
+                                 separator
                                  (query-replace-descr (cdr from-to))))
                        query-replace-defaults))
              (symbol-value query-replace-from-history-variable)))
            (minibuffer-allow-text-properties t) ; separator uses text-properties
            (prompt
-            (if (and query-replace-defaults query-replace-from-to-separator)
+            (if (and query-replace-defaults separator)
                 (format "%s (default %s): " prompt (car query-replace-from-to-history))
               (format "%s: " prompt)))
            (from
@@ -166,7 +177,7 @@ wants to replace FROM with TO."
           (cons (caar query-replace-defaults)
                 (query-replace-compile-replacement
                  (cdar query-replace-defaults) regexp-flag))
-        (let* ((to (if (and (string-match query-replace-from-to-separator from)
+        (let* ((to (if (and (string-match separator from)
                             (get-text-property (match-beginning 0) 'separator from))
                        (query-replace-compile-replacement
                         (substring-no-properties from (match-end 0)) regexp-flag)))