Follow-up fix for InvalidAddressError messages

[taketo1113]

Background

In the following Pull Request, an issue was fixed where the error message for InvalidAddressError did not include the invalid IP address:

• Fix InvalidAddressError message #70
• Fix Wrong InvalidAddressError message #60

This Pull Request fixes additional cases where the invalid IP address is still not shown in the InvalidAddressError message, as well as cases where the error message shows a numeric value instead of an address format.

Details

Invalid address is not shown

When an invalid non-IPv4 address value is passed to IPAddr#new, @addr is not set. As a result, the error message ends up missing the invalid address.
In this case, the argument (left) passed to the in6_addr method, where the exception is raised, is now included in the error message.

For example:

IPAddr.new("INVALID")
/Users/taketo/.rbenv/versions/4.0-dev/lib/ruby/4.0.0+1/ipaddr.rb:758:in 'IPAddr#in6_addr': invalid address:  (IPAddr::InvalidAddressError)

Numeric value instead of an address representation

In some cases, the address shown in the error message is a numeric value such as 42540766411282592856903984951653826560 instead of a human-readable address format like 2001:db8::.
This Pull Request updates the error messages to display the address in a human-readable format.

For example:

IPAddr.new('2001:db8::').ipv4_mapped
/Users/taketo/.rbenv/versions/4.0-dev/lib/ruby/4.0.0+1/ipaddr.rb:371:in 'IPAddr#ipv4_mapped': not an IPv4 address: 42540766411282592856903984951653826560 (IPAddr::InvalidAddressError)

The following methods are updated to improve their error messages:

• #ipv4_mapped
• #ipv4_compat
• #ip6_arpa
• #ip6_int

Expected behavior

# IPAddr#new with invalid string
IPAddr.new("INVALID")
/Users/taketo/path/ipaddr/lib/ipaddr.rb:758:in 'IPAddr#in6_addr': invalid address: INVALID (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "invalid address: #{left}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	from /Users/taketo/path/ipaddr/lib/ipaddr.rb:693:in 'IPAddr#initialize'
...

# IPAddr#ipv4_mapped with IPv6 address
IPAddr.new('2001:db8::').ipv4_mapped
/Users/taketo/path/ipaddr/lib/ipaddr.rb:371:in 'IPAddr#ipv4_mapped': not an IPv4 address: 2001:db8:: (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "not an IPv4 address: #{to_s}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

# IPAddr#ipv4_compat with IPv6 address
IPAddr.new('2001:db8::').ipv4_compat
/Users/taketo/path/ipaddr/lib/ipaddr.rb:383:in 'IPAddr#ipv4_compat': not an IPv4 address: 2001:db8:: (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "not an IPv4 address: #{to_s}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

# IPAddr#ip6_arpa with IPv4 address
IPAddr.new("192.168.2.1").ip6_arpa
/Users/taketo/path/ipaddr/lib/ipaddr.rb:416:in 'IPAddr#ip6_arpa': not an IPv6 address: 192.168.2.1 (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "not an IPv6 address: #{to_s}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

# IPAddr#ip6_int with IPv4 address
IPAddr.new("192.168.2.1").ip6_int
/Users/taketo/path/ipaddr/lib/ipaddr.rb:424:in 'IPAddr#ip6_int': not an IPv6 address: 192.168.2.1 (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "not an IPv6 address: #{to_s}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Actual behavior

$ ruby -v
ruby 4.0.0dev (2025-12-17T12:11:27Z master aee4b24829) +PRISM [arm64-darwin25]

IPAddr::VERSION
=> "1.2.8"

# IPAddr#new with invalid string
IPAddr.new("INVALID")
/Users/taketo/.rbenv/versions/4.0-dev/lib/ruby/4.0.0+1/ipaddr.rb:758:in 'IPAddr#in6_addr': invalid address:  (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "invalid address: #{@addr}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
	from /Users/taketo/.rbenv/versions/4.0-dev/lib/ruby/4.0.0+1/ipaddr.rb:693:in 'IPAddr#initialize'
...

# IPAddr#ipv4_mapped with IPv6 address
IPAddr.new('2001:db8::').ipv4_mapped
/Users/taketo/.rbenv/versions/4.0-dev/lib/ruby/4.0.0+1/ipaddr.rb:371:in 'IPAddr#ipv4_mapped': not an IPv4 address: 42540766411282592856903984951653826560 (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "not an IPv4 address: #{@addr}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

# IPAddr#ipv4_compat with IPv6 address
IPAddr.new('2001:db8::').ipv4_compat
/Users/taketo/.rbenv/versions/4.0-dev/lib/ruby/4.0.0+1/ipaddr.rb:383:in 'IPAddr#ipv4_compat': not an IPv4 address: 42540766411282592856903984951653826560 (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "not an IPv4 address: #{@addr}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

# IPAddr#ip6_arpa with IPv4 address
IPAddr.new("192.168.2.1").ip6_arpa
/Users/taketo/.rbenv/versions/4.0-dev/lib/ruby/4.0.0+1/ipaddr.rb:416:in 'IPAddr#ip6_arpa': not an IPv6 address: 3232236033 (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "not an IPv6 address: #{@addr}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

# IPAddr#ip6_int with IPv4 address
IPAddr.new("192.168.2.1").ip6_int
/Users/taketo/.rbenv/versions/4.0-dev/lib/ruby/4.0.0+1/ipaddr.rb:424:in 'IPAddr#ip6_int': not an IPv6 address: 3232236033 (IPAddr::InvalidAddressError)

      raise InvalidAddressError, "not an IPv6 address: #{@addr}"
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^