Remove fixnum restriction on some display vars

This is a minor patch to remove some fixnum restrictions.
Many more such patches are needed, but one thing at a time.
* doc/emacs/custom.texi (Examining): Update fill-column example.
* src/buffer.c (fill-column, left-margin, tab-width)
(buffer-saved-size, left-margin-width, right-margin-width)
(left-fringe-width, right-fringe-width, scroll-bar-width)
(scroll-bar-height, buffer-display-count):
Allow any integer; do not restrict to fixnums.
* src/character.h (SANE_TAB_WIDTH): Do not assume tab_width
is a nonnegative fixnum.
(sanitize_tab_width): Take a Lisp_Object integer, not an
EMACS_INT.  Only use changed.
* src/data.c (store_symval_forwarding): Remove unnecessary
SYMBOLP since the predicate (e.g., Qintegerp) is always a
symbol (leave the test in as an eassert).  Avoid assignments
inside if-conditions.
* src/fileio.c (Fdo_auto_save): Do not assume
buffer-saved-size is a fixnum.  Avoid undefined behavior
on EMACS_INT overflow by multiplying a fixnum by at most 4,
not by at most 13.
* src/window.c (set_window_buffer): When buffer-display-count
is too large for a fixnum, make it a bignum.
* src/xdisp.c (FILL_COLUMN_INDICATOR_NEEDED): Remove macro, ...
(fill_column_indicator_column): ... replacing with this new function.
All uses changed.  The function is a bit pickier, to prevent
problems with non-character fixnums and columns out of range
for int, and to remove the assumption that integers are in
fixnum range.
(append_space_for_newline, extend_face_to_end_of_line):
Avoid undefined behavior with signed integer overflow.
Simplify.

1 files changed, 5 insertions, 4 deletions

diff --git a/src/character.h b/src/character.h
index 5dff85aed47..cc57a2a7d5c 100644
--- a/src/character.h
+++ b/src/character.h
@@ -558,12 +558,13 @@ enum
 
 /* Return a non-outlandish value for the tab width.  */
 
-#define SANE_TAB_WIDTH(buf) \
-  sanitize_tab_width (XFIXNAT (BVAR (buf, tab_width)))
+#define SANE_TAB_WIDTH(buf) sanitize_tab_width (BVAR (buf, tab_width))
+
 INLINE int
-sanitize_tab_width (EMACS_INT width)
+sanitize_tab_width (Lisp_Object width)
 {
-  return 0 < width && width <= 1000 ? width : 8;
+  return (FIXNUMP (width) && 0 < XFIXNUM (width) && XFIXNUM (width) <= 1000
+          ? XFIXNUM (width) : 8);
 }
 
 /* Return the width of ASCII character C.  The width is measured by