Remove documentation of undefined behavior.

* doc/lispref/positions.texi (Character Motion):
* doc/lispref/markers.texi (Moving Markers):
(Creating Markers): Comment out undefined behavior.

* src/marker.c (set_marker): Remove documentation of undefined behavior.

doc/lispref/ChangeLog

@@ -1,3 +1,9 @@
+2013-08-16  Xue Fuqiao  <xfq.free@gmail.com>
+
+	* positions.texi (Character Motion):
+	* markers.texi (Moving Markers):
+	(Creating Markers): Comment out undefined behavior.
+
 2013-08-15  Xue Fuqiao  <xfq.free@gmail.com>
 
 	* markers.texi (The Region): Add/move indexes.

doc/lispref/markers.texi

@@ -216,11 +216,14 @@ new marker that points to the same place and the same buffer as does
 The new marker's insertion type is specified by the argument
 @var{insertion-type}.  @xref{Marker Insertion Types}.
 
+@c This behavior used to be documented until 2013/08.
+@ignore
 If passed an integer argument less than 1, @code{copy-marker} returns a
 new marker that points to the beginning of the current buffer.  If
 passed an integer argument greater than the length of the buffer,
 @code{copy-marker} returns a new marker that points to the end of the
 buffer.
+@end ignore
 
 @example
 @group
@@ -351,11 +354,15 @@ This function moves @var{marker} to @var{position}
 in @var{buffer}.  If @var{buffer} is not provided, it defaults to
 the current buffer.
 
+@c This behavior used to be documented until 2013/08.
+@ignore
 If @var{position} is less than 1, @code{set-marker} moves @var{marker}
 to the beginning of the buffer.  If @var{position} is greater than the
 size of the buffer (@pxref{Point}), @code{set-marker} moves marker to
-the end of the buffer.  If @var{position} is @code{nil} or a marker
-that points nowhere, then @var{marker} is set to point nowhere.
+the end of the buffer.
+@end ignore
+If @var{position} is @code{nil} or a marker that points nowhere, then
+@var{marker} is set to point nowhere.
 
 The value returned is @var{marker}.
 

doc/lispref/positions.texi

@@ -146,9 +146,13 @@ that.
 
 @deffn Command goto-char position
 This function sets point in the current buffer to the value
-@var{position}.  If @var{position} is less than 1, it moves point to the
-beginning of the buffer.  If @var{position} is greater than the length
-of the buffer, it moves point to the end.
+@var{position}.
+@c This behavior used to be documented until 2013/08.
+@ignore
+If @var{position} is less than 1, it moves point to the beginning of
+the buffer.  If @var{position} is greater than the length of the
+buffer, it moves point to the end.
+@end ignore
 
 If narrowing is in effect, @var{position} still counts from the
 beginning of the buffer, but point cannot go outside the accessible

doc/lispref/text.texi

@@ -240,6 +240,7 @@ Major and minor modes can add functions to
 copied out of the buffer.
 @end defun
 
+@c FIXME: `filter-buffer-substring-function' should be documented.
 @defvar filter-buffer-substring-functions
 This variable is a wrapper hook (@pxref{Running Hooks}), whose members
 should be functions that accept four arguments: @var{fun},

lisp/follow.el

@@ -1259,6 +1259,8 @@ non-first windows in Follow mode."
 
 	;; If the region is visible, make it look good when spanning
 	;; multiple windows.
+
+	;; FIXME: Why not use `use-region-p' here?
 	(when (region-active-p)
 	  (follow-maximize-region
 	   (selected-window) windows win-start-end)))

src/ChangeLog

@@ -1,3 +1,7 @@
+2013-08-16  Xue Fuqiao  <xfq.free@gmail.com>
+
+	* marker.c (set_marker): Remove documentation of undefined behavior.
+
 2013-08-15  Lars Magne Ingebrigtsen  <larsi@gnus.org>
 
 	* image.c (imagemagick_compute_animated_image): Animate correctly

src/marker.c

@@ -536,11 +536,8 @@ set_marker_internal (Lisp_Object marker, Lisp_Object position,
 DEFUN ("set-marker", Fset_marker, Sset_marker, 2, 3, 0,
        doc: /* Position MARKER before character number POSITION in BUFFER.
 If BUFFER is omitted or nil, it defaults to the current buffer.  If
-POSITION is less than 1, MARKER is moved to the beginning of the
-buffer.  If POSITION is greater than the size of the buffer, marker is
-moved to the end of the buffer.  If POSITION is nil, makes marker
-point nowhere so it no longer slows down editing in any buffer.
-Returns MARKER.  */)
+POSITION is nil, makes marker point nowhere so it no longer slows down
+editing in any buffer.  Returns MARKER.  */)
   (Lisp_Object marker, Lisp_Object position, Lisp_Object buffer)
 {
   return set_marker_internal (marker, position, buffer, 0);