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

[Stephen Berman <stephen.berman@gmx.net>]

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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) DWIM: it puts point at the end of a history
element longer than window-width, and if such an element is a single
line, the next <up> displays the previous history element.  Otherwise,
<up> moves by visual lines (specifically also in multi-line history
elements, including those with lines longer than window-width).

(I wanted to add tests for this, but I haven't been able to figure out
how to emulate minibuffer history navigation non-interactively.)

In GNU Emacs 26.0.50 (build 30, x86_64-pc-linux-gnu, GTK+ Version 3.22.8)
 of 2017-05-29 built on rosalinde
Repository revision: c503188f8079ae73d95abd0bce0f53d104b03205
Windowing system distributor 'The X.Org Foundation', version 11.0.11901000


2017-06-01  Stephen Berman  <stephen.berman@gmx.net>

	Improve navigation through minibuffer history

	* lisp/simple.el (previous-line-or-history-element): If the
	element extends beyond window-width, go to its logical end,
	since that is the natural target for editing history elements.
	If it consists of a single line, move by logical lines to hit
	beginning-of-buffer immediately and get the previous history
	element.  Otherwise, move by visual lines.


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diff --git a/lisp/simple.el b/lisp/simple.el
index ea3a495fbc..1b96bce773 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.
@@ -2162,10 +2171,9 @@ 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)))))))
+	 ;; If the line extends beyond window-width, go to its logical end,
+	 ;; since that is the natural target for editing history elements.
+	 (unless (eolp) (end-of-line)))))))
 
 (defun next-complete-history-element (n)
   "Get next history element which completes the minibuffer before the point.