* src/keymap.c (Fmake_composed_keymap): Move to subr.el.

* lisp/subr.el (make-composed-keymap): Move from C.  Change calling
convention, and improve docstring to bring attention to a subtle point.
* lisp/minibuffer.el (completing-read-default): Adjust accordingly.

3 files changed, 26 insertions, 9 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 28d78fa7302..6a6abdf7e42 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2011-08-03  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * subr.el (make-composed-keymap): Move from C.  Change calling
+        convention, and improve docstring to bring attention to a subtle point.
+        * minibuffer.el (completing-read-default): Adjust accordingly.
+
 2011-08-03  Michael Albinus  <michael.albinus@gmx.de>
 
         * net/tramp-sh.el (tramp-open-connection-setup-interactive-shell)
diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index d62b377954d..0a2774de572 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -2754,15 +2754,12 @@ See `completing-read' for the meaning of the arguments."
                      base-keymap
                    ;; Layer minibuffer-local-filename-completion-map
                    ;; on top of the base map.
-                   ;; Use make-composed-keymap so that set-keymap-parent
-                   ;; doesn't modify minibuffer-local-filename-completion-map.
-                   (let ((map (make-composed-keymap
-                               minibuffer-local-filename-completion-map)))
-                     ;; Set base-keymap as the parent, so that nil bindings
-                     ;; in minibuffer-local-filename-completion-map can
-                     ;; override bindings in base-keymap.
-                     (set-keymap-parent map base-keymap)
-                     map)))
+                   (make-composed-keymap
+                    minibuffer-local-filename-completion-map
+                    ;; Set base-keymap as the parent, so that nil bindings
+                    ;; in minibuffer-local-filename-completion-map can
+                    ;; override bindings in base-keymap.
+                    base-keymap)))
          (result (read-from-minibuffer prompt initial-input keymap
                                        nil hist def inherit-input-method)))
     (when (and (equal result "") def)
diff --git a/lisp/subr.el b/lisp/subr.el
index ef19797012a..d57c507a548 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -526,6 +526,20 @@ but optional second arg NODIGITS non-nil treats them like other chars."
           (define-key map (char-to-string loop) 'digit-argument)
           (setq loop (1+ loop))))))
 
+(defun make-composed-keymap (maps &optional parent)
+  "Construct a new keymap composed of MAPS and inheriting from PARENT.
+When looking up a key in the returned map, the key is looked in each
+keymap of MAPS in turn until a binding is found.
+If no binding is found in MAPS, the lookup continues in PARENT, if non-nil.
+As always with keymap inheritance, a nil binding in MAPS overrides
+any corresponding binding in PARENT, but it does not override corresponding
+bindings in other keymaps of MAPS.
+MAPS can be a list of keymaps or a single keymap.
+PARENT if non-nil should be a keymap."
+  `(keymap
+    ,@(if (keymapp maps) (list maps) maps)
+    ,@parent))
+
 (defun define-key-after (keymap key definition &optional after)
   "Add binding in KEYMAP for KEY => DEFINITION, right after AFTER's binding.
 This is like `define-key' except that the binding for KEY is placed