Merge bitcoin-core/secp256k1#1283: Get rid of secp256k1_fe_const_b

69e1ec0 Get rid of secp256k1_fe_const_b (Pieter Wuille)

Pull request description:

  Replaces bitcoin#1282.

  Its only remaining use is in a test introduced in bitcoin#1118, and it is easily replaced by the new `secp256k1_fe_add_int` from bitcoin#1217.

ACKs for top commit:
  real-or-random:
    utACK 69e1ec0

Tree-SHA512: 6ada192e0643fc5326198b60f019a5081444f9ba0a5b8ba6236f2a526829d8e5e479556600a604d9bc96c7ba86e3aab813f93c66679287d2135e95a2b75f5d3e

src/group_impl.h

@@ -73,8 +73,6 @@ static const secp256k1_ge secp256k1_ge_const_g = SECP256K1_G;
 #endif
 /* End of section generated by sage/gen_exhaustive_groups.sage. */
 
-static const secp256k1_fe secp256k1_fe_const_b = SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, SECP256K1_B);
-
 static void secp256k1_ge_set_gej_zinv(secp256k1_ge *r, const secp256k1_gej *a, const secp256k1_fe *zi) {
     secp256k1_fe zi2;
     secp256k1_fe zi3;

src/tests.c

@@ -4498,7 +4498,7 @@ static void ecmult_const_mult_xonly(void) {
             random_field_element_test(&x);
             secp256k1_fe_sqr(&c, &x);
             secp256k1_fe_mul(&c, &c, &x);
-            secp256k1_fe_add(&c, &secp256k1_fe_const_b);
+            secp256k1_fe_add_int(&c, SECP256K1_B);
         } while (secp256k1_fe_is_square_var(&c));
         /* If i is odd, n=d*x for random non-zero d. */
         if (i & 1) {