bug#5030: 23.1.50; Unexpected minibuffer tab completion behavior

[Matthew Dempsky <matthew@dempsky.org>]

On Tue, Nov 24, 2009 at 6:24 PM, Matthew Dempsky wrote:
> The last patch I posted achieves the latter behavior.  Combining with
> the (proof-of-concept) patch below, I seem to achieve the former
> (personally more desirable) behavior.

I think the patch below is better yet.  The second hunk fixes a bug
where `minibuffer-completion-help' assumes that it can directly
compare the input string against the list of candidate completion
strings (e.g., for `find-file', `string' will be bound to something
like `/path/to/a' while `completions' will be a list of file names
like ("aaa" "aab" . 10)).

The first hunk then improves on my last patch's behavior by if you
complete "x" to "xy" when there's also "xyz" available and the
*Completions* buffer is visible, it leaves it visible rather than
hiding it just because "xy" is now an exact match.  (I'm still playing
around with this to see how it actually feels.)

--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -489,10 +489,8 @@ E = after completion we now have an Exact match.
 					minibuffer-completion-table
 					minibuffer-completion-predicate)))
             (if completed
-                ;; We could also decide to refresh the completions,
-                ;; if they're displayed (and assuming there are
-                ;; completions left).
-                (minibuffer-hide-completions)
+		(when (get-buffer-window "*Completions*" 0)
+		  (minibuffer-completion-help))
               ;; Show the completion table, if requested.
               (cond
                ((not exact)
@@ -1003,7 +1001,9 @@ variables.")
     (message nil)
     (if (and completions
              (or (consp (cdr completions))
-                 (not (equal (car completions) string))))
+                 (not (test-completion completion
+				       minibuffer-completion-table
+				       minibuffer-completion-predicate))))
         (let* ((last (last completions))
                (base-size (cdr last))
                ;; If the *Completions* buffer is shown in a new