Treat out-of-range positions consistently

If a position argument to get-byte etc. is an out-of-range integer,
treat it the same regardless of whether it is a fixnum or a bignum.
* src/buffer.c (fix_position): New function.
* src/buffer.c (validate_region):
* src/character.c (Fget_byte):
* src/coding.c (Ffind_coding_systems_region_internal)
(Fcheck_coding_systems_region):
* src/composite.c (Ffind_composition_internal):
* src/editfns.c (Fposition_bytes, Fchar_after, Fchar_before)
(Finsert_buffer_substring, Fcompare_buffer_substrings)
(Fnarrow_to_region):
* src/fns.c (Fsecure_hash_algorithms):
* src/font.c (Finternal_char_font, Ffont_at):
* src/fringe.c (Ffringe_bitmaps_at_pos):
* src/search.c (search_command):
* src/textprop.c (get_char_property_and_overlay):
* src/window.c (Fpos_visible_in_window_p):
* src/xdisp.c (Fwindow_text_pixel_size):
Use it instead of CHECK_FIXNUM_COERCE_MARKER, so that
the code is simpler and treats bignums consistently with fixnums.
* src/buffer.h (CHECK_FIXNUM_COERCE_MARKER): Define here
rather than in lisp.h, and reimplement in terms of fix_position
so that it treats bignums consistently with fixnums.
* src/lisp.h (CHECK_FIXNUM_COERCE_MARKER): Move to buffer.h.
* src/textprop.c (validate_interval_range): Signal with original
bounds rather than modified ones.

14 files changed, 111 insertions, 164 deletions

diff --git a/src/buffer.c b/src/buffer.c
index cc7d4e4817c..70598a7a22a 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -131,6 +131,23 @@ CHECK_OVERLAY (Lisp_Object x)
   CHECK_TYPE (OVERLAYP (x), Qoverlayp, x);
 }
 
+/* Convert the position POS to an EMACS_INT that fits in a fixnum.
+   Yield POS's value if POS is already a fixnum, POS's marker position
+   if POS is a marker, and MOST_NEGATIVE_FIXNUM or
+   MOST_POSITIVE_FIXNUM if POS is a negative or positive bignum.
+   Signal an error if POS is not of the proper form.  */
+
+EMACS_INT
+fix_position (Lisp_Object pos)
+{
+  if (FIXNUMP (pos))
+    return XFIXNUM (pos);
+  if (MARKERP (pos))
+    return marker_position (pos);
+  CHECK_TYPE (BIGNUMP (pos), Qinteger_or_marker_p, pos);
+  return !NILP (Fnatnump (pos)) ? MOST_POSITIVE_FIXNUM : MOST_NEGATIVE_FIXNUM;
+}
+
 /* These setters are used only in this file, so they can be private.
    The public setters are inline functions defined in buffer.h.  */
 static void
@@ -2257,19 +2274,20 @@ so the buffer is truly empty after this.  */)
 }
 
 void
-validate_region (register Lisp_Object *b, register Lisp_Object *e)
+validate_region (Lisp_Object *b, Lisp_Object *e)
 {
-  CHECK_FIXNUM_COERCE_MARKER (*b);
-  CHECK_FIXNUM_COERCE_MARKER (*e);
+  EMACS_INT beg = fix_position (*b), end = fix_position (*e);
 
-  if (XFIXNUM (*b) > XFIXNUM (*e))
+  if (end < beg)
     {
-      Lisp_Object tem;
-      tem = *b;  *b = *e;  *e = tem;
+      EMACS_INT tem = beg;  beg = end;  end = tem;
     }
 
-  if (! (BEGV <= XFIXNUM (*b) && XFIXNUM (*e) <= ZV))
+  if (! (BEGV <= beg && end <= ZV))
     args_out_of_range_3 (Fcurrent_buffer (), *b, *e);
+
+  *b = make_fixnum (beg);
+  *e = make_fixnum (end);
 }
 
 /* Advance BYTE_POS up to a character boundary
diff --git a/src/buffer.h b/src/buffer.h
index fd05fdd37de..31f497ea40a 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -1150,6 +1150,8 @@ extern Lisp_Object interval_insert_behind_hooks;
 extern Lisp_Object interval_insert_in_front_hooks;
 
 
+extern EMACS_INT fix_position (Lisp_Object);
+#define CHECK_FIXNUM_COERCE_MARKER(x) ((x) = make_fixnum (fix_position (x)))
 extern void delete_all_overlays (struct buffer *);
 extern void reset_buffer (struct buffer *);
 extern void compact_buffer (struct buffer *);
diff --git a/src/character.c b/src/character.c
index 5d419a2e836..d71cb3f145c 100644
--- a/src/character.c
+++ b/src/character.c
@@ -931,10 +931,10 @@ character is not ASCII nor 8-bit character, an error is signaled.  */)
         }
       else
         {
-          CHECK_FIXNUM_COERCE_MARKER (position);
-          if (XFIXNUM (position) < BEGV || XFIXNUM (position) >= ZV)
+          EMACS_INT fixed_pos = fix_position (position);
+          if (! (BEGV <= fixed_pos && fixed_pos < ZV))
             args_out_of_range_3 (position, make_fixnum (BEGV), make_fixnum (ZV));
-          pos = XFIXNAT (position);
+          pos = fixed_pos;
           p = CHAR_POS_ADDR (pos);
         }
       if (NILP (BVAR (current_buffer, enable_multibyte_characters)))
diff --git a/src/coding.c b/src/coding.c
index 8b54281c0bf..0bea2a0c2bc 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -9023,23 +9023,23 @@ DEFUN ("find-coding-systems-region-internal",
     }
   else
     {
-      CHECK_FIXNUM_COERCE_MARKER (start);
-      CHECK_FIXNUM_COERCE_MARKER (end);
-      if (XFIXNUM (start) < BEG || XFIXNUM (end) > Z || XFIXNUM (start) > XFIXNUM (end))
+      EMACS_INT s = fix_position (start);
+      EMACS_INT e = fix_position (end);
+      if (! (BEG <= s && s <= e && e <= Z))
         args_out_of_range (start, end);
       if (NILP (BVAR (current_buffer, enable_multibyte_characters)))
         return Qt;
-      start_byte = CHAR_TO_BYTE (XFIXNUM (start));
-      end_byte = CHAR_TO_BYTE (XFIXNUM (end));
-      if (XFIXNUM (end) - XFIXNUM (start) == end_byte - start_byte)
+      start_byte = CHAR_TO_BYTE (s);
+      end_byte = CHAR_TO_BYTE (e);
+      if (e - s == end_byte - start_byte)
         return Qt;
 
-      if (XFIXNUM (start) < GPT && XFIXNUM (end) > GPT)
+      if (s < GPT && GPT < e)
         {
-          if ((GPT - XFIXNUM (start)) < (XFIXNUM (end) - GPT))
-            move_gap_both (XFIXNUM (start), start_byte);
+          if (GPT - s < e - GPT)
+            move_gap_both (s, start_byte);
           else
-            move_gap_both (XFIXNUM (end), end_byte);
+            move_gap_both (e, end_byte);
         }
     }
 
@@ -9277,25 +9277,25 @@ is nil.  */)
     }
   else
     {
-      CHECK_FIXNUM_COERCE_MARKER (start);
-      CHECK_FIXNUM_COERCE_MARKER (end);
-      if (XFIXNUM (start) < BEG || XFIXNUM (end) > Z || XFIXNUM (start) > XFIXNUM (end))
+      EMACS_INT s = fix_position (start);
+      EMACS_INT e = fix_position (end);
+      if (! (BEG <= s && s <= e && e <= Z))
         args_out_of_range (start, end);
       if (NILP (BVAR (current_buffer, enable_multibyte_characters)))
         return Qnil;
-      start_byte = CHAR_TO_BYTE (XFIXNUM (start));
-      end_byte = CHAR_TO_BYTE (XFIXNUM (end));
-      if (XFIXNUM (end) - XFIXNUM (start) == end_byte - start_byte)
+      start_byte = CHAR_TO_BYTE (s);
+      end_byte = CHAR_TO_BYTE (e);
+      if (e - s == end_byte - start_byte)
         return Qnil;
 
-      if (XFIXNUM (start) < GPT && XFIXNUM (end) > GPT)
+      if (s < GPT && GPT < e)
         {
-          if ((GPT - XFIXNUM (start)) < (XFIXNUM (end) - GPT))
-            move_gap_both (XFIXNUM (start), start_byte);
+          if (GPT - s < e - GPT)
+            move_gap_both (s, start_byte);
           else
-            move_gap_both (XFIXNUM (end), end_byte);
+            move_gap_both (e, end_byte);
         }
-      pos = XFIXNUM (start);
+      pos = s;
     }
 
   list = Qnil;
diff --git a/src/composite.c b/src/composite.c
index 84de334ce0d..a00a4541f5e 100644
--- a/src/composite.c
+++ b/src/composite.c
@@ -1839,27 +1839,24 @@ See `find-composition' for more details.  */)
   ptrdiff_t start, end, from, to;
   int id;
 
-  CHECK_FIXNUM_COERCE_MARKER (pos);
+  EMACS_INT fixed_pos = fix_position (pos);
   if (!NILP (limit))
-    {
-      CHECK_FIXNUM_COERCE_MARKER (limit);
-      to = min (XFIXNUM (limit), ZV);
-    }
+    to = clip_to_bounds (PTRDIFF_MIN, fix_position (limit), ZV);
   else
     to = -1;
 
   if (!NILP (string))
     {
       CHECK_STRING (string);
-      if (XFIXNUM (pos) < 0 || XFIXNUM (pos) > SCHARS (string))
+      if (! (0 <= fixed_pos && fixed_pos <= SCHARS (string)))
         args_out_of_range (string, pos);
     }
   else
     {
-      if (XFIXNUM (pos) < BEGV || XFIXNUM (pos) > ZV)
+      if (! (BEGV <= fixed_pos && fixed_pos <= ZV))
         args_out_of_range (Fcurrent_buffer (), pos);
     }
-  from = XFIXNUM (pos);
+  from = fixed_pos;
 
   if (!find_composition (from, to, &start, &end, &prop, string))
     {
@@ -1870,12 +1867,12 @@ See `find-composition' for more details.  */)
         return list3 (make_fixnum (start), make_fixnum (end), gstring);
       return Qnil;
     }
-  if ((end <= XFIXNUM (pos) || start > XFIXNUM (pos)))
+  if (! (start <= fixed_pos && fixed_pos < end))
     {
       ptrdiff_t s, e;
 
       if (find_automatic_composition (from, to, &s, &e, &gstring, string)
-          && (e <= XFIXNUM (pos) ? e > end : s < start))
+          && (e <= fixed_pos ? e > end : s < start))
         return list3 (make_fixnum (s), make_fixnum (e), gstring);
     }
   if (!composition_valid_p (start, end, prop))
diff --git a/src/editfns.c b/src/editfns.c
index cbc1082b2cc..90520d0dced 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -948,10 +948,10 @@ DEFUN ("position-bytes", Fposition_bytes, Sposition_bytes, 1, 1, 0,
 If POSITION is out of range, the value is nil.  */)
   (Lisp_Object position)
 {
-  CHECK_FIXNUM_COERCE_MARKER (position);
-  if (XFIXNUM (position) < BEG || XFIXNUM (position) > Z)
+  EMACS_INT pos = fix_position (position);
+  if (! (BEG <= pos && pos <= Z))
     return Qnil;
-  return make_fixnum (CHAR_TO_BYTE (XFIXNUM (position)));
+  return make_fixnum (CHAR_TO_BYTE (pos));
 }
 
 DEFUN ("byte-to-position", Fbyte_to_position, Sbyte_to_position, 1, 1, 0,
@@ -1068,11 +1068,11 @@ If POS is out of range, the value is nil.  */)
     }
   else
     {
-      CHECK_FIXNUM_COERCE_MARKER (pos);
-      if (XFIXNUM (pos) < BEGV || XFIXNUM (pos) >= ZV)
+      EMACS_INT p = fix_position (pos);
+      if (! (BEGV <= p && p < ZV))
         return Qnil;
 
-      pos_byte = CHAR_TO_BYTE (XFIXNUM (pos));
+      pos_byte = CHAR_TO_BYTE (p);
     }
 
   return make_fixnum (FETCH_CHAR (pos_byte));
@@ -1102,12 +1102,12 @@ If POS is out of range, the value is nil.  */)
     }
   else
     {
-      CHECK_FIXNUM_COERCE_MARKER (pos);
+      EMACS_INT p = fix_position (pos);
 
-      if (XFIXNUM (pos) <= BEGV || XFIXNUM (pos) > ZV)
+      if (! (BEGV < p && p <= ZV))
         return Qnil;
 
-      pos_byte = CHAR_TO_BYTE (XFIXNUM (pos));
+      pos_byte = CHAR_TO_BYTE (p);
     }
 
   if (!NILP (BVAR (current_buffer, enable_multibyte_characters)))
@@ -1726,21 +1726,8 @@ using `string-make-multibyte' or `string-make-unibyte', which see.  */)
   if (!BUFFER_LIVE_P (bp))
     error ("Selecting deleted buffer");
 
-  if (NILP (start))
-    b = BUF_BEGV (bp);
-  else
-    {
-      CHECK_FIXNUM_COERCE_MARKER (start);
-      b = XFIXNUM (start);
-    }
-  if (NILP (end))
-    e = BUF_ZV (bp);
-  else
-    {
-      CHECK_FIXNUM_COERCE_MARKER (end);
-      e = XFIXNUM (end);
-    }
-
+  b = !NILP (start) ? fix_position (start) : BUF_BEGV (bp);
+  e = !NILP (end) ? fix_position (end) : BUF_ZV (bp);
   if (b > e)
     temp = b, b = e, e = temp;
 
@@ -1794,21 +1781,8 @@ determines whether case is significant or ignored.  */)
         error ("Selecting deleted buffer");
     }
 
-  if (NILP (start1))
-    begp1 = BUF_BEGV (bp1);
-  else
-    {
-      CHECK_FIXNUM_COERCE_MARKER (start1);
-      begp1 = XFIXNUM (start1);
-    }
-  if (NILP (end1))
-    endp1 = BUF_ZV (bp1);
-  else
-    {
-      CHECK_FIXNUM_COERCE_MARKER (end1);
-      endp1 = XFIXNUM (end1);
-    }
-
+  begp1 = !NILP (start1) ? fix_position (start1) : BUF_BEGV (bp1);
+  endp1 = !NILP (end1) ? fix_position (end1) : BUF_ZV (bp1);
   if (begp1 > endp1)
     temp = begp1, begp1 = endp1, endp1 = temp;
 
@@ -1832,21 +1806,8 @@ determines whether case is significant or ignored.  */)
         error ("Selecting deleted buffer");
     }
 
-  if (NILP (start2))
-    begp2 = BUF_BEGV (bp2);
-  else
-    {
-      CHECK_FIXNUM_COERCE_MARKER (start2);
-      begp2 = XFIXNUM (start2);
-    }
-  if (NILP (end2))
-    endp2 = BUF_ZV (bp2);
-  else
-    {
-      CHECK_FIXNUM_COERCE_MARKER (end2);
-      endp2 = XFIXNUM (end2);
-    }
-
+  begp2 = !NILP (start2) ? fix_position (start2) : BUF_BEGV (bp2);
+  endp2 = !NILP (end2) ? fix_position (end2) : BUF_ZV (bp2);
   if (begp2 > endp2)
     temp = begp2, begp2 = endp2, endp2 = temp;
 
@@ -2700,29 +2661,27 @@ See also `save-restriction'.
 When calling from Lisp, pass two arguments START and END:
 positions (integers or markers) bounding the text that should
 remain visible.  */)
-  (register Lisp_Object start, Lisp_Object end)
+  (Lisp_Object start, Lisp_Object end)
 {
-  CHECK_FIXNUM_COERCE_MARKER (start);
-  CHECK_FIXNUM_COERCE_MARKER (end);
+  EMACS_INT s = fix_position (start), e = fix_position (end);
 
-  if (XFIXNUM (start) > XFIXNUM (end))
+  if (e < s)
     {
-      Lisp_Object tem;
-      tem = start; start = end; end = tem;
+      EMACS_INT tem = s; s = e; e = tem;
     }
 
-  if (!(BEG <= XFIXNUM (start) && XFIXNUM (start) <= XFIXNUM (end) && XFIXNUM (end) <= Z))
+  if (!(BEG <= s && s <= e && e <= Z))
     args_out_of_range (start, end);
 
-  if (BEGV != XFIXNAT (start) || ZV != XFIXNAT (end))
+  if (BEGV != s || ZV != e)
     current_buffer->clip_changed = 1;
 
-  SET_BUF_BEGV (current_buffer, XFIXNAT (start));
-  SET_BUF_ZV (current_buffer, XFIXNAT (end));
-  if (PT < XFIXNAT (start))
-    SET_PT (XFIXNAT (start));
-  if (PT > XFIXNAT (end))
-    SET_PT (XFIXNAT (end));
+  SET_BUF_BEGV (current_buffer, s);
+  SET_BUF_ZV (current_buffer, e);
+  if (PT < s)
+    SET_PT (s);
+  if (e < PT)
+    SET_PT (e);
   /* Changing the buffer bounds invalidates any recorded current column.  */
   invalidate_current_column ();
   return Qnil;
diff --git a/src/fns.c b/src/fns.c
index 80012fa9d28..138082e07c8 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -5187,22 +5187,8 @@ extract_data_from_object (Lisp_Object spec,
       struct buffer *bp = XBUFFER (object);
       set_buffer_internal (bp);
 
-      if (NILP (start))
-        b = BEGV;
-      else
-        {
-          CHECK_FIXNUM_COERCE_MARKER (start);
-          b = XFIXNUM (start);
-        }
-
-      if (NILP (end))
-        e = ZV;
-      else
-        {
-          CHECK_FIXNUM_COERCE_MARKER (end);
-          e = XFIXNUM (end);
-        }
-
+      b = !NILP (start) ? fix_position (start) : BEGV;
+      e = !NILP (end) ? fix_position (end) : ZV;
       if (b > e)
         {
           EMACS_INT temp = b;
diff --git a/src/font.c b/src/font.c
index 2a456300619..0c9e752e089 100644
--- a/src/font.c
+++ b/src/font.c
@@ -4606,10 +4606,10 @@ DEFUN ("internal-char-font", Finternal_char_font, Sinternal_char_font, 1, 2, 0,
       Lisp_Object window;
       struct window *w;
 
-      CHECK_FIXNUM_COERCE_MARKER (position);
-      if (! (BEGV <= XFIXNUM (position) && XFIXNUM (position) < ZV))
+      EMACS_INT fixed_pos = fix_position (position);
+      if (! (BEGV <= fixed_pos && fixed_pos < ZV))
         args_out_of_range_3 (position, make_fixnum (BEGV), make_fixnum (ZV));
-      pos = XFIXNUM (position);
+      pos = fixed_pos;
       pos_byte = CHAR_TO_BYTE (pos);
       if (NILP (ch))
         c = FETCH_CHAR (pos_byte);
@@ -5013,24 +5013,26 @@ character at index specified by POSITION.  */)
   (Lisp_Object position, Lisp_Object window, Lisp_Object string)
 {
   struct window *w = decode_live_window (window);
+  EMACS_INT pos;
 
   if (NILP (string))
     {
       if (XBUFFER (w->contents) != current_buffer)
         error ("Specified window is not displaying the current buffer");
-      CHECK_FIXNUM_COERCE_MARKER (position);
-      if (! (BEGV <= XFIXNUM (position) && XFIXNUM (position) < ZV))
+      pos = fix_position (position);
+      if (! (BEGV <= pos && pos < ZV))
         args_out_of_range_3 (position, make_fixnum (BEGV), make_fixnum (ZV));
     }
   else
     {
       CHECK_FIXNUM (position);
       CHECK_STRING (string);
-      if (! (0 <= XFIXNUM (position) && XFIXNUM (position) < SCHARS (string)))
+      pos = XFIXNUM (position);
+      if (! (0 <= pos && pos < SCHARS (string)))
         args_out_of_range (string, position);
     }
 
-  return font_at (-1, XFIXNUM (position), NULL, w, string);
+  return font_at (-1, pos, NULL, w, string);
 }
 
 #if 0
diff --git a/src/fringe.c b/src/fringe.c
index 2a46e3c34f2..d8d80bb3fe9 100644
--- a/src/fringe.c
+++ b/src/fringe.c
@@ -1675,10 +1675,10 @@ Return nil if POS is not visible in WINDOW.  */)
 
   if (!NILP (pos))
     {
-      CHECK_FIXNUM_COERCE_MARKER (pos);
-      if (! (BEGV <= XFIXNUM (pos) && XFIXNUM (pos) <= ZV))
+      EMACS_INT p = fix_position (pos);
+      if (! (BEGV <= p && p <= ZV))
         args_out_of_range (window, pos);
-      textpos = XFIXNUM (pos);
+      textpos = p;
     }
   else if (w == XWINDOW (selected_window))
     textpos = PT;
diff --git a/src/lisp.h b/src/lisp.h
index 49923be702a..d3b1c39c8fb 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3012,14 +3012,6 @@ CHECK_FIXNAT (Lisp_Object x)
       CHECK_RANGED_INTEGER (x, 0, TYPE_MAXIMUM (type));                 \
   } while (false)
 
-#define CHECK_FIXNUM_COERCE_MARKER(x)                                   \
-  do {                                                                  \
-    if (MARKERP ((x)))                                                  \
-      XSETFASTINT (x, marker_position (x));                             \
-    else                                                                \
-      CHECK_TYPE (FIXNUMP (x), Qinteger_or_marker_p, x);                \
-  } while (false)
-
 INLINE double
 XFLOATINT (Lisp_Object n)
 {
diff --git a/src/search.c b/src/search.c
index 818bb4af246..7389fbef0ee 100644
--- a/src/search.c
+++ b/src/search.c
@@ -1028,8 +1028,7 @@ search_command (Lisp_Object string, Lisp_Object bound, Lisp_Object noerror,
     }
   else
     {
-      CHECK_FIXNUM_COERCE_MARKER (bound);
-      lim = XFIXNUM (bound);
+      lim = fix_position (bound);
       if (n > 0 ? lim < PT : lim > PT)
         error ("Invalid search bound (wrong side of point)");
       if (lim > ZV)
diff --git a/src/textprop.c b/src/textprop.c
index ee048336ac0..960dba3f8dc 100644
--- a/src/textprop.c
+++ b/src/textprop.c
@@ -131,6 +131,7 @@ validate_interval_range (Lisp_Object object, Lisp_Object *begin,
 {
   INTERVAL i;
   ptrdiff_t searchpos;
+  Lisp_Object begin0 = *begin, end0 = *end;
 
   CHECK_STRING_OR_BUFFER (object);
   CHECK_FIXNUM_COERCE_MARKER (*begin);
@@ -155,7 +156,7 @@ validate_interval_range (Lisp_Object object, Lisp_Object *begin,
 
       if (!(BUF_BEGV (b) <= XFIXNUM (*begin) && XFIXNUM (*begin) <= XFIXNUM (*end)
             && XFIXNUM (*end) <= BUF_ZV (b)))
-        args_out_of_range (*begin, *end);
+        args_out_of_range (begin0, end0);
       i = buffer_intervals (b);
 
       /* If there's no text, there are no properties.  */
@@ -170,7 +171,7 @@ validate_interval_range (Lisp_Object object, Lisp_Object *begin,
 
       if (! (0 <= XFIXNUM (*begin) && XFIXNUM (*begin) <= XFIXNUM (*end)
              && XFIXNUM (*end) <= len))
-        args_out_of_range (*begin, *end);
+        args_out_of_range (begin0, end0);
       i = string_intervals (object);
 
       if (len == 0)
@@ -611,7 +612,7 @@ get_char_property_and_overlay (Lisp_Object position, register Lisp_Object prop,
 {
   struct window *w = 0;
 
-  CHECK_FIXNUM_COERCE_MARKER (position);
+  EMACS_INT pos = fix_position (position);
 
   if (NILP (object))
     XSETBUFFER (object, current_buffer);
@@ -628,14 +629,14 @@ get_char_property_and_overlay (Lisp_Object position, register Lisp_Object prop,
       Lisp_Object *overlay_vec;
       struct buffer *obuf = current_buffer;
 
-      if (XFIXNUM (position) < BUF_BEGV (XBUFFER (object))
-          || XFIXNUM (position) > BUF_ZV (XBUFFER (object)))
+      if (! (BUF_BEGV (XBUFFER (object)) <= pos
+             && pos <= BUF_ZV (XBUFFER (object))))
         xsignal1 (Qargs_out_of_range, position);
 
       set_buffer_temp (XBUFFER (object));
 
       USE_SAFE_ALLOCA;
-      GET_OVERLAYS_AT (XFIXNUM (position), overlay_vec, noverlays, NULL, false);
+      GET_OVERLAYS_AT (pos, overlay_vec, noverlays, NULL, false);
       noverlays = sort_overlays (overlay_vec, noverlays, w);
 
       set_buffer_temp (obuf);
@@ -662,7 +663,7 @@ get_char_property_and_overlay (Lisp_Object position, register Lisp_Object prop,
 
   /* Not a buffer, or no appropriate overlay, so fall through to the
      simpler case.  */
-  return Fget_text_property (position, prop, object);
+  return Fget_text_property (make_fixnum (pos), prop, object);
 }
 
 DEFUN ("get-char-property", Fget_char_property, Sget_char_property, 2, 3, 0,
diff --git a/src/window.c b/src/window.c
index 8cdad27b664..075fd4e550c 100644
--- a/src/window.c
+++ b/src/window.c
@@ -1895,10 +1895,7 @@ POS, ROWH is the visible height of that row, and VPOS is the row number
   if (EQ (pos, Qt))
     posint = -1;
   else if (!NILP (pos))
-    {
-      CHECK_FIXNUM_COERCE_MARKER (pos);
-      posint = XFIXNUM (pos);
-    }
+    posint = fix_position (pos);
   else if (w == XWINDOW (selected_window))
     posint = PT;
   else
diff --git a/src/xdisp.c b/src/xdisp.c
index 58d7ca5cb71..61c798c59e8 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -10413,10 +10413,7 @@ include the height of both, if present, in the return value.  */)
         start = pos;
     }
   else
-    {
-      CHECK_FIXNUM_COERCE_MARKER (from);
-      start = min (max (XFIXNUM (from), BEGV), ZV);
-    }
+    start = clip_to_bounds (BEGV, fix_position (from), ZV);
 
   if (NILP (to))
     end = ZV;
@@ -10430,10 +10427,7 @@ include the height of both, if present, in the return value.  */)
         end = pos;
     }
   else
-    {
-      CHECK_FIXNUM_COERCE_MARKER (to);
-      end = max (start, min (XFIXNUM (to), ZV));
-    }
+    end = clip_to_bounds (start, fix_position (to), ZV);
 
   if (!NILP (x_limit) && RANGED_FIXNUMP (0, x_limit, INT_MAX))
     max_x = XFIXNUM (x_limit);