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, 3 insertions, 3 deletions

diff --git a/src/floatfns.c b/src/floatfns.c
index a913aad5aac..0a85df47dec 100644
--- a/src/floatfns.c
+++ b/src/floatfns.c
@@ -268,9 +268,9 @@ DEFUN ("abs", Fabs, Sabs, 1, 1, 0,
     }
   else
     {
-      if (mpz_sgn (XBIGNUM (arg)->value) < 0)
+      if (mpz_sgn (*xbignum_val (arg)) < 0)
         {
-          mpz_neg (mpz[0], XBIGNUM (arg)->value);
+          mpz_neg (mpz[0], *xbignum_val (arg));
           arg = make_integer_mpz ();
         }
     }
@@ -315,7 +315,7 @@ This is the same as the exponent of a float.  */)
       value = ivalue - 1;
     }
   else if (!FIXNUMP (arg))
-    value = mpz_sizeinbase (XBIGNUM (arg)->value, 2) - 1;
+    value = mpz_sizeinbase (*xbignum_val (arg), 2) - 1;
   else
     {
       EMACS_INT i = XFIXNUM (arg);