bug#27191: 26.0.50; Long history items in minibuffer (again)

[Stephen Berman]

On Thu, 01 Jun 2017 22:46:15 +0200 Stephen Berman <stephen.berman@gmx.net> 
wrote:

> 0. emacs -Q
> 1. C-x C-f
> ~/foo/bar/very/long/file/name/that/overflows/minibuffer/window/line/when/displayed
> <RET>
> 2. C-x C-f <up>
> => The file name entered in step 1 appears in the minibuffer, with point
>    on the "w" of "when" (i.e., column 80, the end of the visual line).
>
> If at step 2 instead of <up> you type `M-p', then point is at the end of
> the file name in the minibuffer.  This is what I expected for <up> too.
>
> The result with <up> is due to the fix for bug#22544.  In the bug thread
> (http://lists.gnu.org/archive/html/bug-gnu-emacs/2016-02/msg00357.html),
> the above problem was noted:
>
>> > Can't we special-case a line that isn't broken into several visual
>> > lines, and put the cursor at the end of such lines only?  That'd be
>> > the best.
>> 
>> The problem here is that like bash and other shells with histories do,
>> we need to put the cursor at the end of the previous history element
>> so the user can start editing it immediately (usually deleting the chars
>> from the end of the logical line).  OTOH, a subsequent <UP> should
>> continue navigating the history and put the next previous element to the
>> minibuffer.  But then <UP> can't be used to move between visual lines.
>> This is a lose-lose situation, unless we'll find some clever DWIM.
>
> The attached patch isn't particularly clever, but (unless I've
> overlooked something)

Oops, I did.  Here's the corrected patch:

diff --git a/lisp/simple.el b/lisp/simple.el
index ea3a495fbc..5c7dab8f74 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -2140,7 +2140,16 @@ previous-line-or-history-element
                         (current-column)))))
     (condition-case nil
        (with-no-warnings
-         (previous-line arg))
+         ;; If the history element consists of a single line longer
+         ;; than window-width, move by logical lines to hit
+         ;; beginning-of-buffer immediately and get the previous
+         ;; history element.  Otherwise, move by visual lines.
+         (if (and (save-excursion
+                    (end-of-line)
+                    (> (current-column) (window-width)))
+                  (= (line-number-at-pos) 1))
+             (previous-logical-line arg)
+           (previous-line arg)))
       (beginning-of-buffer
        ;; Restore old position since `line-move-visual' moves point to
        ;; the beginning of the line when it fails to go to the previous line.
@@ -2157,15 +2166,12 @@ previous-line-or-history-element
           (if (= (line-number-at-pos) 1)
               (move-to-column (+ old-column (1- (minibuffer-prompt-end))))
             (move-to-column old-column))
-        ;; Put the cursor at the end of the visual line instead of the
-        ;; logical line, so the next `previous-line-or-history-element'
-        ;; would move to the previous history element, not to a possible upper
-        ;; visual line from the end of logical line in `line-move-visual' mode.
-        (end-of-visual-line)
-        ;; Since `end-of-visual-line' puts the cursor at the beginning
-        ;; of the next visual line, move it one char back to the end
-        ;; of the first visual line (bug#22544).
-        (unless (eolp) (backward-char 1)))))))
+        ;; Put the cursor at the end of the logical line, even if it extends
+         ;; beyond window-width, since that is the natural target for editing
+         ;; history elements (bug#27191).  The condition above makes sure the
+         ;; next `previous-line-or-history-element' will move to the previous
+         ;; history element in either case.
+         (end-of-line))))))
 
 (defun next-complete-history-element (n)
   "Get next history element which completes the minibuffer before the point.

Steve Berman