* numeric.c (fix_pow): Handle special cases when base is 0, 1 or +1

  [Bug ruby#5713] [Rubyspec:7af675cde9f]

numeric.c

@@ -2840,6 +2840,13 @@ fix_pow(VALUE x, VALUE y)
     if (FIXNUM_P(y)) {
 	long b = FIX2LONG(y);
 
+	if (a == 1) return INT2FIX(1);
+	if (a == -1) {
+	    if (b % 2 == 0)
+		return INT2FIX(1);
+	    else
+		return INT2FIX(-1);
+	}
 	if (b < 0)
 	    return rb_funcall(rb_rational_raw1(x), rb_intern("**"), 1, y);
 
@@ -2849,27 +2856,19 @@ fix_pow(VALUE x, VALUE y)
 	    if (b > 0) return INT2FIX(0);
 	    return DBL2NUM(INFINITY);
 	}
-	if (a == 1) return INT2FIX(1);
-	if (a == -1) {
-	    if (b % 2 == 0)
-		return INT2FIX(1);
-	    else
-		return INT2FIX(-1);
-	}
 	return int_pow(a, b);
     }
     switch (TYPE(y)) {
       case T_BIGNUM:
 
-	if (rb_funcall(y, '<', 1, INT2FIX(0)))
-	    return rb_funcall(rb_rational_raw1(x), rb_intern("**"), 1, y);
-
-	if (a == 0) return INT2FIX(0);
 	if (a == 1) return INT2FIX(1);
 	if (a == -1) {
 	    if (int_even_p(y)) return INT2FIX(1);
 	    else return INT2FIX(-1);
 	}
+	if (rb_funcall(y, '<', 1, INT2FIX(0)))
+	    return rb_funcall(rb_rational_raw1(x), rb_intern("**"), 1, y);
+	if (a == 0) return INT2FIX(0);
 	x = rb_int2big(FIX2LONG(x));
 	return rb_big_pow(x, y);
       case T_FLOAT: