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.

7 files changed, 100 insertions, 110 deletions

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]