It's not clear to me if dropping support for this functionality was intentional.

Chain of events:

- #21689 removed test coverage due to a misunderstanding due, I believe, to this functionality being generally supported by all platforms except macOS which does not and returns a different format
- #21756 removed support and caused this regression
- #21690 restores the test coverage that would have caught this regression

Currently, neither the test coverage before #21689 nor the coverage restored by #21690 pass since the merge of #21756.

{
    
    
    const std::map<std::string, std::string> canonical_representations_ipv6{
        {"0000:0000:0000:0000:0000:0000:0000:0000", "::"},
        {"000:0000:000:00:0:00:000:0000", "::"},
        {"000:000:000:000:000:000:000:000", "::"},
        {"00:00:00:00:00:00:00:00", "::"},
        {"0:0:0:0:0:0:0:0", "::"},
        {"0:0:0:0:0:0:0:1", "::1"},
        {"2001:0:0:1:0:0:0:1", "2001:0:0:1::1"},
        {"2001:0db8:0:0:1:0:0:1", "2001:db8::1:0:0:1"},
        {"2001:0db8:85a3:0000:0000:8a2e:0370:7334", "2001:db8:85a3::8a2e:370:7334"},
        {"2001:0db8::0001", "2001:db8::1"},
        {"2001:0db8::0001:0000", "2001:db8::1:0"},
        {"2001:0db8::1:0:0:1", "2001:db8::1:0:0:1"},
        {"2001:db8:0000:0:1::1", "2001:db8::1:0:0:1"},
        {"2001:db8:0000:1:1:1:1:1", "2001:db8:0:1:1:1:1:1"},
        {"2001:db8:0:0:0:0:2:1", "2001:db8::2:1"},
        {"2001:db8:0:0:0::1", "2001:db8::1"},
        {"2001:db8:0:0:1:0:0:1", "2001:db8::1:0:0:1"},
        {"2001:db8:0:0:1::1", "2001:db8::1:0:0:1"},
        {"2001:DB8:0:0:1::1", "2001:db8::1:0:0:1"},