Respect -proto_dist flag when specified multiple times

[jonatanklosko]

Currently specifying multiple instances of -proto_dist ignores the flag altogether.

$ erl -name foo@::1 -proto_dist inet6_tcp
Erlang/OTP 28 [DEVELOPMENT] [erts-15.0.1] [source] [64-bit] [smp:10:10] [ds:10:10:10] [async-threads:1] [jit]

Eshell V15.0.1 (press Ctrl+G to abort, type help(). for help)
(foo@::1)1> sys:get_state(erl_epmd).
{state,#Port<0.4>,62687,foo,inet6}

$ erl -name foo@::1 -proto_dist inet6_tcp -proto_dist inet6_tcp
Erlang/OTP 28 [DEVELOPMENT] [erts-15.0.1] [source] [64-bit] [smp:10:10] [ds:10:10:10] [async-threads:1] [jit]

Eshell V15.0.1 (press Ctrl+G to abort, type help(). for help)
(foo@::1)1> sys:get_state(erl_epmd).
{state,#Port<0.4>,62693,foo,inet}

[github-actions]

CT Test Results

    2 files     70 suites   1h 2m 17s ⏱️
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1 715 runs  1 441 ✅ 274 💤 0 ❌

Results for commit 4de3cc9.

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[jhogberg]

Thanks for the PR! Can you log a warning when the option is specified multiple times (c.f. #2227)?

[jonatanklosko]

Sidenote: similar functions above do not have that warning.

A follow up question: is there a reason we process proto_dist as a list, instead of getting the first item? In other words, is there a case where the user would pass -proto_dist [proto1, proto2]. The docs say -proto_dist Proto, indicating a single value is expected.

[jhogberg]

Indeed, not all functions have that warning, nor do many other places elsewhere in the codebase that uses init:get_argument/1 (most seem to either ignore the flag or grab the first argument, both of them silently). It's rather inconsistent unfortunately, but there's nothing wrong with fixing it as we go.

As for processing as a list the intent seems to be supporting multiple protocols at the same time, but as you noted we haven't documented that anywhere so it's not supported.

[jonatanklosko]

Note: the warning shows up twice, since we read the value in two places.

[jhogberg]

I think that's fine. :-)

[jhogberg]

Hi again, the tests ran fine and I'm ready to merge this as soon as the commits are squashed :-)

[jonatanklosko]

@jhogberg rebased and squashed!

[jhogberg]

Merged, thanks again for the PR!