codegen.c: allow constant folding for negative integer modulo.
@@ -823,8 +823,11 @@ gen_binop(codegen_scope *s, mrb_sym op, uint16_t dst)
if (!mrb_num_shift(s->mrb, n0, -n, &n)) return FALSE;
}
else if (op == MRB_OPSYM_2(s->mrb, mod)) {
- if (n0 < 0 || n < 0) return FALSE;
- n = n0 % n;
+ mrb_int n1 = n0 % n;
+ if ((n0 < 0) != (n < 0) && n1 != 0) {
+ n1 += n;
+ }
+ n = n1;
}
else if (op == MRB_OPSYM_2(s->mrb, and)) {
n = n0 & n;
