Be more careful about pointers to bignum vals

This uses ‘const’ to be better at catching bugs that
mistakenly attempt to modify a bignum value.
Lisp bignums are supposed to be immutable.
* src/alloc.c (make_pure_bignum):
* src/fns.c (sxhash_bignum):
Accept Lisp_Object instead of struct Lisp_Bignum *, as that’s
simpler now.  Caller changed.
* src/bignum.h (bignum_val, xbignum_val): New inline functions.
Prefer them to &i->value and XBIGNUM (i)->value, since they
apply ‘const’ to the result.
* src/timefns.c (lisp_to_timespec): Use mpz_t const *
to point to a bignum value.

1 files changed, 15 insertions, 15 deletions

diff --git a/src/data.c b/src/data.c
index cf9f8e56133..8344bfdd3d5 100644
--- a/src/data.c
+++ b/src/data.c
@@ -525,7 +525,7 @@ DEFUN ("natnump", Fnatnump, Snatnump, 1, 1, 0,
   (Lisp_Object object)
 {
   return ((FIXNUMP (object) ? 0 <= XFIXNUM (object)
-           : BIGNUMP (object) && 0 <= mpz_sgn (XBIGNUM (object)->value))
+           : BIGNUMP (object) && 0 <= mpz_sgn (*xbignum_val (object)))
           ? Qt : Qnil);
 }
 
@@ -2481,7 +2481,7 @@ arithcompare (Lisp_Object num1, Lisp_Object num2,
       else if (isnan (f1))
         lt = eq = gt = false;
       else
-        i2 = mpz_cmp_d (XBIGNUM (num2)->value, f1);
+        i2 = mpz_cmp_d (*xbignum_val (num2), f1);
     }
   else if (FIXNUMP (num1))
     {
@@ -2502,7 +2502,7 @@ arithcompare (Lisp_Object num1, Lisp_Object num2,
           i2 = XFIXNUM (num2);
         }
       else
-        i2 = mpz_sgn (XBIGNUM (num2)->value);
+        i2 = mpz_sgn (*xbignum_val (num2));
     }
   else if (FLOATP (num2))
     {
@@ -2510,12 +2510,12 @@ arithcompare (Lisp_Object num1, Lisp_Object num2,
       if (isnan (f2))
         lt = eq = gt = false;
       else
-        i1 = mpz_cmp_d (XBIGNUM (num1)->value, f2);
+        i1 = mpz_cmp_d (*xbignum_val (num1), f2);
     }
   else if (FIXNUMP (num2))
-    i1 = mpz_sgn (XBIGNUM (num1)->value);
+    i1 = mpz_sgn (*xbignum_val (num1));
   else
-    i1 = mpz_cmp (XBIGNUM (num1)->value, XBIGNUM (num2)->value);
+    i1 = mpz_cmp (*xbignum_val (num1), *xbignum_val (num2));
 
   if (eq)
     {
@@ -3005,7 +3005,7 @@ usage: (- &optional NUMBER-OR-MARKER &rest MORE-NUMBERS-OR-MARKERS)  */)
         return make_int (-XFIXNUM (a));
       if (FLOATP (a))
         return make_float (-XFLOAT_DATA (a));
-      mpz_neg (mpz[0], XBIGNUM (a)->value);
+      mpz_neg (mpz[0], *xbignum_val (a));
       return make_integer_mpz ();
     }
   return arith_driver (Asub, nargs, args, a);
@@ -3214,7 +3214,7 @@ representation.  */)
 
   if (BIGNUMP (value))
     {
-      mpz_t *nonneg = &XBIGNUM (value)->value;
+      mpz_t const *nonneg = xbignum_val (value);
       if (mpz_sgn (*nonneg) < 0)
         {
           mpz_com (mpz[0], *nonneg);
@@ -3245,10 +3245,10 @@ In this case, the sign bit is duplicated.  */)
     {
       if (EQ (value, make_fixnum (0)))
         return value;
-      if (mpz_sgn (XBIGNUM (count)->value) < 0)
+      if (mpz_sgn (*xbignum_val (count)) < 0)
         {
           EMACS_INT v = (FIXNUMP (value) ? XFIXNUM (value)
-                         : mpz_sgn (XBIGNUM (value)->value));
+                         : mpz_sgn (*xbignum_val (value)));
           return make_fixnum (v < 0 ? -1 : 0);
         }
       overflow_error ();
@@ -3291,8 +3291,8 @@ expt_integer (Lisp_Object x, Lisp_Object y)
   if (TYPE_RANGED_FIXNUMP (unsigned long, y))
     exp = XFIXNUM (y);
   else if (MOST_POSITIVE_FIXNUM < ULONG_MAX && BIGNUMP (y)
-           && mpz_fits_ulong_p (XBIGNUM (y)->value))
-    exp = mpz_get_ui (XBIGNUM (y)->value);
+           && mpz_fits_ulong_p (*xbignum_val (y)))
+    exp = mpz_get_ui (*xbignum_val (y));
   else
     overflow_error ();
 
@@ -3311,7 +3311,7 @@ Markers are converted to integers.  */)
     return make_int (XFIXNUM (number) + 1);
   if (FLOATP (number))
     return (make_float (1.0 + XFLOAT_DATA (number)));
-  mpz_add_ui (mpz[0], XBIGNUM (number)->value, 1);
+  mpz_add_ui (mpz[0], *xbignum_val (number), 1);
   return make_integer_mpz ();
 }
 
@@ -3326,7 +3326,7 @@ Markers are converted to integers.  */)
     return make_int (XFIXNUM (number) - 1);
   if (FLOATP (number))
     return (make_float (-1.0 + XFLOAT_DATA (number)));
-  mpz_sub_ui (mpz[0], XBIGNUM (number)->value, 1);
+  mpz_sub_ui (mpz[0], *xbignum_val (number), 1);
   return make_integer_mpz ();
 }
 
@@ -3337,7 +3337,7 @@ DEFUN ("lognot", Flognot, Slognot, 1, 1, 0,
   CHECK_INTEGER (number);
   if (FIXNUMP (number))
     return make_fixnum (~XFIXNUM (number));
-  mpz_com (mpz[0], XBIGNUM (number)->value);
+  mpz_com (mpz[0], *xbignum_val (number));
   return make_integer_mpz ();
 }