gen_tcp:connect/3 fails when addr in the SockAddr map is loopback

[ptome]

Describe the bug
gen_tcp:connect/3 fails when addr in the SockAddr map is loopback.

To Reproduce
Open a listening socket:

$ nc -vv -l -p 4321
listening on [any] 4321 ...

Open a TCP connection to loopback, from Erlang:

$ erl
Erlang/OTP 28 [RELEASE CANDIDATE 1] [erts-15.2.2] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [jit:ns]

Eshell V15.2.2 (press Ctrl+G to abort, type help(). for help)
1> {ok, Sock} = gen_tcp:connect(#{family => inet, addr => loopback, port => 4321}, [binary, {packet, 0}]).
** exception exit: {function_clause,[{inet_tcp,do_connect,
                                               [#{port => 4321,addr => loopback,family => inet},
                                                [binary,{packet,0}],
                                                infinity],
                                               [{file,"inet_tcp.erl"},{line,119}]},
                                     {gen_tcp,connect,3,[{file,"gen_tcp.erl"},{line,464}]},
                                     {erl_eval,do_apply,7,[{file,"erl_eval.erl"},{line,922}]},
                                     {erl_eval,expr,6,[{file,"erl_eval.erl"},{line,666}]},
                                     {shell,exprs,7,[{file,"shell.erl"},{line,935}]},
                                     {shell,eval_exprs,7,[{file,"shell.erl"},{line,891}]},
                                     {shell,eval_loop,4,[{file,"shell.erl"},{line,876}]}]}
     in function  gen_tcp:connect/3 (gen_tcp.erl, line 469)
2> 

Expected behavior
gen_tcp:connect/3 should work with a sockaddr_in() when addr is loopback.

-type sockaddr_in() ::
          #{family := inet, port := port_number(), addr := any | broadcast | loopback | in_addr()}.

Affected versions
Tested on OTP 28 RC1, current master. Likely affects previous versions since 24.3 (commit 94e68e5).

Additional context
I was trying to understand if #5044 was solved by the OTP 24.3 change to gen_tcp:connect/3. I'm not sure if I'm doing something wrong, but I can't get it to work with loopback.

From the stack strace, inet_tcp:do_connect doesn't have a clause for the atoms. It only matches {A,B,C,D} tuples (IP address).

This is called from inet_tcp:connect after gen_tcp:connect2 in:

otp/lib/kernel/src/gen_tcp.erl

Lines 598 to 600 in 03b6047

	connect2(SockAddr, Opts0, Timer) ->
	{Mod, Opts} = inet:tcp_module(Opts0, SockAddr),
	Mod:connect(SockAddr, Opts, inet:timeout(Timer)).

I can solve the problem by calling inet:translate_ip/2 before Mod:connect in connect2, but I'm not sure if this is the correct way to fix it.

connect2(#{addr := Addr, family := Family} = SockAddr, Opts0, Timer) ->
    {Mod, Opts} = inet:tcp_module(Opts0, SockAddr),
    SockAddr2 = SockAddr#{addr := inet:translate_ip(Addr, Family)},
    Mod:connect(SockAddr2, Opts, inet:timeout(Timer)).

If it is a bug, I would like to work on a PR, including documentation and tests if needed. I may need some guidance on the correct way of fixing it.