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

[Chong Yidong]

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)))