Avoid infinite loop on negative exponent; fix #3677

src/numeric.c

@@ -60,26 +60,23 @@ num_pow(mrb_state *mrb, mrb_value x)
     mrb_int base = mrb_fixnum(x);
     mrb_int exp = mrb_fixnum(y);
     mrb_int result = 1;
-    mrb_bool ok = TRUE;
 
+    if (exp < 0) goto float_pow;
     for (;;) {
       if (exp & 1) {
         if (mrb_int_mul_overflow(result, base, &result)) {
-          ok = FALSE;
-          break;
+          goto float_pow;
         }
       }
       exp >>= 1;
       if (exp == 0) break;
       if (mrb_int_mul_overflow(base, base, &base)) {
-        ok = FALSE;
-        break;
+        goto float_pow;
       }
     }
-    if (ok) {
     return mrb_fixnum_value(result);
   }
-  }
+ float_pow:
   d = pow(mrb_to_flo(mrb, x), mrb_to_flo(mrb, y));
   return mrb_float_value(mrb, d);
 }