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.

8 files changed, 101 insertions, 110 deletions

diff --git a/doc/emacs/custom.texi b/doc/emacs/custom.texi
index 8a8ac5d0464..bdd6decb6b5 100644
--- a/doc/emacs/custom.texi
+++ b/doc/emacs/custom.texi
@@ -801,6 +801,7 @@ Its value is 70
   Automatically becomes buffer-local when set.
   This variable is safe as a file local variable if its value
   satisfies the predicate ‘integerp’.
+  Probably introduced at or before Emacs version 18.
 
 Documentation:
 Column beyond which automatic line-wrapping should happen.
diff --git a/src/buffer.c b/src/buffer.c
index 3b5078a175b..209e29f0f19 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -5603,17 +5603,17 @@ Use the command `abbrev-mode' to change this variable.  */);
 		     doc: /* Non-nil if searches and matches should ignore case.  */);
 
   DEFVAR_PER_BUFFER ("fill-column", &BVAR (current_buffer, fill_column),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Column beyond which automatic line-wrapping should happen.
 Interactively, you can set the buffer local value using \\[set-fill-column].  */);
 
   DEFVAR_PER_BUFFER ("left-margin", &BVAR (current_buffer, left_margin),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Column for the default `indent-line-function' to indent to.
 Linefeed indents to this column in Fundamental mode.  */);
 
   DEFVAR_PER_BUFFER ("tab-width", &BVAR (current_buffer, tab_width),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Distance between tab stops (for display of tab characters), in columns.
 NOTE: This controls the display width of a TAB character, and not
 the size of an indentation step.
@@ -5784,7 +5784,7 @@ If it is nil, that means don't auto-save this buffer.  */);
 Backing up is done before the first time the file is saved.  */);
 
   DEFVAR_PER_BUFFER ("buffer-saved-size", &BVAR (current_buffer, save_length),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Length of current buffer when last read in, saved or auto-saved.
 0 initially.
 -1 means auto-saving turned off until next real save.
@@ -5858,7 +5858,7 @@ In addition, a char-table has six extra slots to control the display of:
 See also the functions `display-table-slot' and `set-display-table-slot'.  */);
 
   DEFVAR_PER_BUFFER ("left-margin-width", &BVAR (current_buffer, left_margin_cols),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Width in columns of left marginal area for display of a buffer.
 A value of nil means no marginal area.
 
@@ -5866,7 +5866,7 @@ Setting this variable does not take effect until a new buffer is displayed
 in a window.  To make the change take effect, call `set-window-buffer'.  */);
 
   DEFVAR_PER_BUFFER ("right-margin-width", &BVAR (current_buffer, right_margin_cols),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Width in columns of right marginal area for display of a buffer.
 A value of nil means no marginal area.
 
@@ -5874,7 +5874,7 @@ Setting this variable does not take effect until a new buffer is displayed
 in a window.  To make the change take effect, call `set-window-buffer'.  */);
 
   DEFVAR_PER_BUFFER ("left-fringe-width", &BVAR (current_buffer, left_fringe_width),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Width of this buffer's left fringe (in pixels).
 A value of 0 means no left fringe is shown in this buffer's window.
 A value of nil means to use the left fringe width from the window's frame.
@@ -5883,7 +5883,7 @@ Setting this variable does not take effect until a new buffer is displayed
 in a window.  To make the change take effect, call `set-window-buffer'.  */);
 
   DEFVAR_PER_BUFFER ("right-fringe-width", &BVAR (current_buffer, right_fringe_width),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Width of this buffer's right fringe (in pixels).
 A value of 0 means no right fringe is shown in this buffer's window.
 A value of nil means to use the right fringe width from the window's frame.
@@ -5900,12 +5900,12 @@ Setting this variable does not take effect until a new buffer is displayed
 in a window.  To make the change take effect, call `set-window-buffer'.  */);
 
   DEFVAR_PER_BUFFER ("scroll-bar-width", &BVAR (current_buffer, scroll_bar_width),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Width of this buffer's vertical scroll bars in pixels.
 A value of nil means to use the scroll bar width from the window's frame.  */);
 
   DEFVAR_PER_BUFFER ("scroll-bar-height", &BVAR (current_buffer, scroll_bar_height),
-		     Qfixnump,
+		     Qintegerp,
 		     doc: /* Height of this buffer's horizontal scroll bars in pixels.
 A value of nil means to use the scroll bar height from the window's frame.  */);
 
@@ -6175,7 +6175,7 @@ Setting this variable is very fast, much faster than scanning all the text in
 the buffer looking for properties to change.  */);
 
   DEFVAR_PER_BUFFER ("buffer-display-count",
-		     &BVAR (current_buffer, display_count), Qfixnump,
+		     &BVAR (current_buffer, display_count), Qintegerp,
 		     doc: /* A number incremented each time this buffer is displayed in a window.
 The function `set-window-buffer' increments it.  */);
 
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
diff --git a/src/data.c b/src/data.c
index 476d28eadbc..c1699aeae73 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1122,20 +1122,21 @@ store_symval_forwarding (lispfwd valcontents, Lisp_Object newval,
 	int offset = XBUFFER_OBJFWD (valcontents)->offset;
 	Lisp_Object predicate = XBUFFER_OBJFWD (valcontents)->predicate;
 
-	if (!NILP (newval))
+	if (!NILP (newval) && !NILP (predicate))
 	  {
-	    if (SYMBOLP (predicate))
+	    eassert (SYMBOLP (predicate));
+	    Lisp_Object choiceprop = Fget (predicate, Qchoice);
+	    if (!NILP (choiceprop))
 	      {
-		Lisp_Object prop;
-
-		if ((prop = Fget (predicate, Qchoice), !NILP (prop)))
-		  {
-		    if (NILP (Fmemq (newval, prop)))
-		      wrong_choice (prop, newval);
-		  }
-		else if ((prop = Fget (predicate, Qrange), !NILP (prop)))
+		if (NILP (Fmemq (newval, choiceprop)))
+		  wrong_choice (choiceprop, newval);
+	      }
+	    else
+	      {
+		Lisp_Object rangeprop = Fget (predicate, Qrange);
+		if (CONSP (rangeprop))
 		  {
-		    Lisp_Object min = XCAR (prop), max = XCDR (prop);
+		    Lisp_Object min = XCAR (rangeprop), max = XCDR (rangeprop);
 		    if (! NUMBERP (newval)
 			|| NILP (CALLN (Fleq, min, newval, max)))
 		      wrong_range (min, max, newval);
diff --git a/src/fileio.c b/src/fileio.c
index 4ee125d7de2..9e9779967dd 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -5802,6 +5802,7 @@ A non-nil CURRENT-ONLY argument means save only current buffer.  */)
 	    && BUF_SAVE_MODIFF (b) < BUF_MODIFF (b)
 	    && BUF_AUTOSAVE_MODIFF (b) < BUF_MODIFF (b)
 	    /* -1 means we've turned off autosaving for a while--see below.  */
+	    && FIXNUMP (BVAR (b, save_length))
 	    && XFIXNUM (BVAR (b, save_length)) >= 0
 	    && (do_handled_files
 		|| NILP (Ffind_file_name_handler (BVAR (b, auto_save_file_name),
@@ -5815,13 +5816,17 @@ A non-nil CURRENT-ONLY argument means save only current buffer.  */)
 		&& before_time.tv_sec - b->auto_save_failure_time < 1200)
 	      continue;
 
+	    enum { growth_factor = 4 };
+	    verify (BUF_BYTES_MAX <= EMACS_INT_MAX / growth_factor);
+
 	    set_buffer_internal (b);
 	    if (NILP (Vauto_save_include_big_deletions)
-		&& (XFIXNAT (BVAR (b, save_length)) * 10
-		    > (BUF_Z (b) - BUF_BEG (b)) * 13)
+		&& FIXNUMP (BVAR (b, save_length))
 		/* A short file is likely to change a large fraction;
 		   spare the user annoying messages.  */
 		&& XFIXNAT (BVAR (b, save_length)) > 5000
+		&& (growth_factor * (BUF_Z (b) - BUF_BEG (b))
+		    < (growth_factor - 1) * XFIXNAT (BVAR (b, save_length)))
 		/* These messages are frequent and annoying for `*mail*'.  */
 		&& !NILP (BVAR (b, filename))
 		&& NILP (no_message))
diff --git a/src/lisp.h b/src/lisp.h
index 876b757bf3f..6db90596899 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -2679,7 +2679,7 @@ struct Lisp_Buffer_Objfwd
   {
     enum Lisp_Fwd_Type type;	/* = Lisp_Fwd_Buffer_Obj */
     int offset;
-    /* One of Qnil, Qfixnump, Qsymbolp, Qstringp, Qfloatp or Qnumberp.  */
+    /* One of Qnil, Qintegerp, Qsymbolp, Qstringp, Qfloatp or Qnumberp.  */
     Lisp_Object predicate;
   };
 
diff --git a/src/window.c b/src/window.c
index ca7cf7a4a61..deeb4f63fe0 100644
--- a/src/window.c
+++ b/src/window.c
@@ -3947,8 +3947,8 @@ set_window_buffer (Lisp_Object window, Lisp_Object buffer,
   b->display_error_modiff = 0;
 
   /* Update time stamps of buffer display.  */
-  if (FIXNUMP (BVAR (b, display_count)))
-    bset_display_count (b, make_fixnum (XFIXNUM (BVAR (b, display_count)) + 1));
+  if (INTEGERP (BVAR (b, display_count)))
+    bset_display_count (b, Fadd1 (BVAR (b, display_count)));
   bset_display_time (b, Fcurrent_time ());
 
   w->window_end_pos = 0;
diff --git a/src/xdisp.c b/src/xdisp.c
index 9eed74cb98a..5f438152341 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -376,17 +376,26 @@ static Lisp_Object list_of_error;
 	       || it->s[IT_BYTEPOS (*it)] == '\t'))			\
        || (IT_BYTEPOS (*it) < ZV_BYTE					\
 	   && (*BYTE_POS_ADDR (IT_BYTEPOS (*it)) == ' '			\
-	       || *BYTE_POS_ADDR (IT_BYTEPOS (*it)) == '\t'))))		\
-
-/* Test all the conditions needed to print the fill column indicator.  */
-#define FILL_COLUMN_INDICATOR_NEEDED(it)			\
-  Vdisplay_fill_column_indicator			\
-  && (it->continuation_lines_width == 0)			\
-  && (!NILP (Vdisplay_fill_column_indicator_column))		\
-  && FIXNATP (Vdisplay_fill_column_indicator_character)		\
-  && ((EQ (Vdisplay_fill_column_indicator_column, Qt)		\
-       && FIXNATP (BVAR (current_buffer, fill_column)))		\
-      || (FIXNATP (Vdisplay_fill_column_indicator_column)))
+	       || *BYTE_POS_ADDR (IT_BYTEPOS (*it)) == '\t'))))
+
+/* If all the conditions needed to print the fill column indicator are
+   met, return the (nonnegative) column number, else return a negative
+   value.  */
+static int
+fill_column_indicator_column (struct it *it)
+{
+  if (Vdisplay_fill_column_indicator
+      && it->continuation_lines_width == 0
+      && CHARACTERP (Vdisplay_fill_column_indicator_character))
+    {
+      Lisp_Object col = (EQ (Vdisplay_fill_column_indicator_column, Qt)
+			 ? BVAR (current_buffer, fill_column)
+			 : Vdisplay_fill_column_indicator_column);
+      if (RANGED_FIXNUMP (0, col, INT_MAX))
+	return XFIXNUM (col);
+    }
+  return -1;
+}
 
 /* True means print newline to stdout before next mini-buffer message.  */
 
@@ -20160,18 +20169,11 @@ append_space_for_newline (struct it *it, bool default_face_p)
 	  /* Corner case for when display-fill-column-indicator-mode
 	     is active and the extra character should be added in the
 	     same place than the line.  */
-	  if ((it->w->pseudo_window_p == 0)
-	      && FILL_COLUMN_INDICATOR_NEEDED(it))
+	  int indicator_column = (it->w->pseudo_window_p == 0
+				  ? fill_column_indicator_column (it)
+				  : -1);
+	  if (0 <= indicator_column)
 	    {
-	       int fill_column_indicator_column = -1;
-
-	       if (EQ (Vdisplay_fill_column_indicator_column, Qt))
-	         fill_column_indicator_column =
-		   XFIXNAT (BVAR (current_buffer, fill_column));
-	       else
-		 fill_column_indicator_column =
-		   XFIXNAT (Vdisplay_fill_column_indicator_column);
-
 	       struct font *font =
 	         default_face->font ?
 		   default_face->font : FRAME_FONT (it->f);
@@ -20179,18 +20181,19 @@ append_space_for_newline (struct it *it, bool default_face_p)
 	         font->average_width ?
 		   font->average_width : font->space_width;
 
-	       const int column_x =
-		 char_width * fill_column_indicator_column +
-		   it->lnum_pixel_width;
-
-	       if (it->current_x == column_x)
+	       int column_x;
+	       if (!INT_MULTIPLY_WRAPV (indicator_column, char_width,
+					&column_x)
+		   && !INT_ADD_WRAPV (it->lnum_pixel_width, column_x,
+				      &column_x)
+		   && it->current_x == column_x)
 	         {
 	           it->c = it->char_to_display =
 		     XFIXNAT (Vdisplay_fill_column_indicator_character);
 	           it->face_id =
 		     merge_faces (it->w, Qfill_column_indicator,
 		                  0, saved_face_id);
-	           face = FACE_FROM_ID(it->f, it->face_id);
+	           face = FACE_FROM_ID (it->f, it->face_id);
 	           goto produce_glyphs;
 	         }
 	    }
@@ -20422,30 +20425,22 @@ extend_face_to_end_of_line (struct it *it)
 	  /* Display fill column indicator if not in modeline or
 	     toolbar and display fill column indicator mode is
 	     active.  */
-	  if ((it->w->pseudo_window_p == 0)
-	      && FILL_COLUMN_INDICATOR_NEEDED(it))
+	  int indicator_column = (it->w->pseudo_window_p == 0
+				  ? fill_column_indicator_column (it)
+				  : -1);
+	  if (0 <= indicator_column)
             {
-	       int fill_column_indicator_column = -1;
-
-	       if (EQ (Vdisplay_fill_column_indicator_column, Qt))
-	         fill_column_indicator_column =
-		   XFIXNAT (BVAR (current_buffer, fill_column));
-	       else
-		 fill_column_indicator_column =
-		   XFIXNAT (Vdisplay_fill_column_indicator_column);
-
 	      struct font *font =
 	        default_face->font ? default_face->font : FRAME_FONT (f);
 	      const int char_width =
 	        font->average_width ?
 		  font->average_width : font->space_width;
 
-	      const int column_x =
-	        char_width * fill_column_indicator_column +
-	          it->lnum_pixel_width;
-
-	      if ((it->current_x <= column_x)
-	          && (column_x <= it->last_visible_x))
+	      int column_x;
+	      if (!INT_MULTIPLY_WRAPV (indicator_column, char_width, &column_x)
+		  && !INT_ADD_WRAPV (it->lnum_pixel_width, column_x, &column_x)
+		  && it->current_x <= column_x
+		  && column_x <= it->last_visible_x)
 	        {
 	          const char saved_char = it->char_to_display;
 	          const struct text_pos saved_pos = it->position;
@@ -20625,45 +20620,33 @@ extend_face_to_end_of_line (struct it *it)
 	it->face_id = face->id;
 
       /* Display fill-column indicator if needed.  */
-      if (FILL_COLUMN_INDICATOR_NEEDED(it))
+      int indicator_column = fill_column_indicator_column (it);
+      if (0 <= indicator_column
+	  && INT_ADD_WRAPV (it->lnum_pixel_width, indicator_column,
+			    &indicator_column))
+	indicator_column = -1;
+      do
 	{
-	  int fill_column_indicator_column = -1;
+	  int saved_face_id;
+	  bool indicate = it->current_x == indicator_column;
+	  if (indicate)
+	    {
+	      saved_face_id = it->face_id;
+	      it->face_id =
+		merge_faces (it->w, Qfill_column_indicator, 0, saved_face_id);
+	      it->c = it->char_to_display =
+		XFIXNAT (Vdisplay_fill_column_indicator_character);
+	    }
 
-	  /* Vdisplay_fill_column_indicator_column accepts the special
-	     value t to use the default fill-column variable.  The
-	     conditions are all defined in the macro
-	     FILL_COLUMN_INDICATOR_NEEDED.  */
-	  if (EQ (Vdisplay_fill_column_indicator_column, Qt))
-	    fill_column_indicator_column =
-	      XFIXNAT (BVAR (current_buffer, fill_column)) + it->lnum_pixel_width;
-	  else
-	    fill_column_indicator_column =
-	      XFIXNAT (Vdisplay_fill_column_indicator_column) + it->lnum_pixel_width;
+	  PRODUCE_GLYPHS (it);
 
-	  do
+	  if (indicate)
 	    {
-	      if (it->current_x == fill_column_indicator_column)
-	        {
-		  const int saved_face_id = it->face_id;
-		  it->face_id =
-		    merge_faces (it->w, Qfill_column_indicator, 0, saved_face_id);
-		  it->c = it->char_to_display =
-		    XFIXNAT (Vdisplay_fill_column_indicator_character);
-		  PRODUCE_GLYPHS (it);
-		  it->face_id = saved_face_id;
-		  it->c = it->char_to_display = ' ';
-	        }
-	      else
-		PRODUCE_GLYPHS (it);
-	    } while (it->current_x <= it->last_visible_x);
+	      it->face_id = saved_face_id;
+	      it->c = it->char_to_display = ' ';
+	    }
 	}
-      else
-	{
-          do
-	    {
-	      PRODUCE_GLYPHS (it);
-            } while (it->current_x <= it->last_visible_x);
-        }
+      while (it->current_x <= it->last_visible_x);
 
       if (WINDOW_RIGHT_MARGIN_WIDTH (it->w) > 0
 	  && (it->glyph_row->used[RIGHT_MARGIN_AREA]