[ruby/ipaddr] Fix exception calling `to_range' after `freeze'

https://github.com/ruby/ipaddr/commit/77fe1fca0a

lib/ipaddr.rb

@@ -411,7 +411,7 @@ class IPAddr
       raise AddressFamilyError, "unsupported address family"
     end
 
-    return clone.set(begin_addr, @family)..clone.set(end_addr, @family)
+    self.class.new(begin_addr, @family)..self.class.new(end_addr, @family)
   end
 
   # Returns the prefix length in bits for the ipaddr.
@@ -583,6 +583,7 @@ class IPAddr
   # those, such as &, |, include? and ==, accept a string, or a packed
   # in_addr value instead of an IPAddr object.
   def initialize(addr = '::', family = Socket::AF_UNSPEC)
+    @mask_addr = nil
     if !addr.kind_of?(String)
       case family
       when Socket::AF_INET, Socket::AF_INET6

test/test_ipaddr.rb

@@ -255,6 +255,28 @@ class TC_IPAddr < Test::Unit::TestCase
     assert_equal("1:2:3:4:5:6:7:8%ab0", a.to_s)
     assert_raise(IPAddr::InvalidAddressError) { a.zone_id = '%' }
   end
+
+  def test_to_range
+    a1 = IPAddr.new("127.0.0.1")
+    range = a1..a1
+    assert_equal(range, a1.to_range)
+    assert_equal(range, a1.freeze.to_range)
+
+    a2 = IPAddr.new("192.168.0.1/16")
+    range = IPAddr.new("192.168.0.0")..IPAddr.new("192.168.255.255")
+    assert_equal(range, a2.to_range)
+    assert_equal(range, a2.freeze.to_range)
+
+    a3 = IPAddr.new("3ffe:505:2::1")
+    range = a3..a3
+    assert_equal(range, a3.to_range)
+    assert_equal(range, a3.freeze.to_range)
+
+    a4 = IPAddr.new("::ffff/127")
+    range = IPAddr.new("::fffe")..IPAddr.new("::ffff")
+    assert_equal(range, a4.to_range)
+    assert_equal(range, a4.freeze.to_range)
+  end
 end
 
 class TC_Operator < Test::Unit::TestCase