bug#3494: 23.0.94; line-move-visual: temporary goal column confused by hscrolling

[Chong Yidong <cyd@stupidchicken.com>]

Please test this patch instead of the one I previously sent (I'll
install it on the trunk as well, for additional testing).

*** emacs/lisp/simple.el.~1.988.~	2009-06-21 00:37:46.000000000 -0400
--- emacs/lisp/simple.el	2009-07-11 12:30:05.000000000 -0400
***************
*** 3956,3965 ****
  (defvar temporary-goal-column 0
    "Current goal column for vertical motion.
  It is the column where point was at the start of the current run
! of vertical motion commands.  It is a floating point number when
! moving by visual lines via `line-move-visual'; this is the
! x-position, in pixels, divided by the default column width.  When
! the `track-eol' feature is doing its job, the value is
  `most-positive-fixnum'.")
  
  (defcustom line-move-ignore-invisible t
--- 3956,3969 ----
  (defvar temporary-goal-column 0
    "Current goal column for vertical motion.
  It is the column where point was at the start of the current run
! of vertical motion commands.
! 
! When moving by visual lines via `line-move-visual', it is a cons
! cell (COL . HSCROLL), where COL is the x-position, in pixels,
! divided by the default column width, and HSCROLL is the number of
! columns by which window is scrolled from left margin.
! 
! When the `track-eol' feature is doing its job, the value is
  `most-positive-fixnum'.")
  
  (defcustom line-move-ignore-invisible t
***************
*** 4059,4075 ****
    (let ((posn (posn-at-point))
  	(opoint (point))
  	x)
!     ;; Reset temporary-goal-column, unless the previous command was a
!     ;; line-motion command or we were called from some other command.
!     (unless (and (floatp temporary-goal-column)
! 		 (memq last-command `(next-line previous-line ,this-command)))
!       (cond ((eq (nth 1 posn) 'right-fringe) ; overflow-newline-into-fringe
! 	     (setq temporary-goal-column (- (window-width) 1)))
! 	    ((setq x (car (posn-x-y posn)))
! 	     (setq temporary-goal-column (/ (float x) (frame-char-width))))))
      ;; Move using `vertical-motion'.
      (or (and (= (vertical-motion
! 		 (cons (or goal-column (truncate temporary-goal-column)) arg))
  		arg)
  	     (or (>= arg 0)
  		 (/= (point) opoint)
--- 4063,4095 ----
    (let ((posn (posn-at-point))
  	(opoint (point))
  	x)
!     ;; Check if the previous command was a line-motion command or we
!     ;; were called from some other command.
!     (cond ((and (consp temporary-goal-column)
! 		(memq last-command `(next-line previous-line ,this-command)))
! 	   ;; If so, there's no need to reset `temporary-goal-column',
! 	   ;; unless the window hscroll has changed.
! 	   (when (/= (window-hscroll) (cdr temporary-goal-column))
! 	     (set-window-hscroll nil 0)
! 	     (setq temporary-goal-column
! 		   (cons (+ (car temporary-goal-column)
! 			    (cdr temporary-goal-column)) 0))))
! 	  ;; Otherwise, we should reset `temporary-goal-column'.
! 	  ;; Handle the `overflow-newline-into-fringe' case:
! 	  ((eq (nth 1 posn) 'right-fringe)
! 	   (setq temporary-goal-column (cons (- (window-width) 1)
! 					     (window-hscroll))))
! 	  ((setq x (car (posn-x-y posn)))
! 	   (setq temporary-goal-column
! 		 (cons (/ (float x) (frame-char-width))
! 		       (window-hscroll)))))
      ;; Move using `vertical-motion'.
      (or (and (= (vertical-motion
! 		 (cons (or goal-column
! 			   (if (consp temporary-goal-column)
! 			       (truncate (car temporary-goal-column))
! 			     temporary-goal-column))
! 		       arg))
  		arg)
  	     (or (>= arg 0)
  		 (/= (point) opoint)
***************
*** 4091,4098 ****
    (let ((inhibit-point-motion-hooks t)
  	(opoint (point))
  	(orig-arg arg))
!     (if (floatp temporary-goal-column)
! 	(setq temporary-goal-column (truncate temporary-goal-column)))
      (unwind-protect
  	(progn
  	  (if (not (memq last-command '(next-line previous-line)))
--- 4111,4119 ----
    (let ((inhibit-point-motion-hooks t)
  	(opoint (point))
  	(orig-arg arg))
!     (if (consp temporary-goal-column)
! 	(setq temporary-goal-column (+ (car temporary-goal-column)
! 				       (cdr temporary-goal-column))))
      (unwind-protect
  	(progn
  	  (if (not (memq last-command '(next-line previous-line)))