Stop using deprecated net.Dialer.DualStack

[joanlopez]

What?

It removes all the uses of net.Dialer.DualStack, because now it's deprecated, and the desired behavior (enabled) is now by default. It also slightly modifies few comments to make that more clear.

Why?

Not sure why staticcheck is not complaining, but I guess it's always good idea to stop using a deprecated field, especially in this case that I can't see any pain.

Checklist

• I have performed a self-review of my code.
• I have added tests for my changes.
• I have run linter locally (make lint) and all checks pass.
• I have run tests locally (make tests) and all tests pass.
• I have commented on my code, particularly in hard-to-understand areas.

Related PR(s)/Issue(s)

N/A

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (7d131d6) 72.48% compared to head (2641660) 72.50%.

❗ Current head 2641660 differs from pull request most recent head b0e8457. Consider uploading reports for the commit b0e8457 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3520      +/-   ##
==========================================
+ Coverage   72.48%   72.50%   +0.01%     
==========================================
  Files         276      276              
  Lines       20842    20840       -2     
==========================================
+ Hits        15108    15110       +2     
+ Misses       4771     4767       -4     
  Partials      963      963              

Flag	Coverage Δ
ubuntu	72.45% <ø> (+<0.01%)	⬆️
windows	72.36% <ø> (+0.01%)	⬆️

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[codebien]

Thanks @joanlopez. So strange staticcheck doesn't complain. How did you catch it?

[joanlopez]

Thanks @joanlopez. So strange staticcheck doesn't complain.

Honestly, I just assumed it was a staticcheck's bug because it's a struct field and/or because it's in the stdlib (or the combination of both), but didn't really care.

But now that you asked 😛, I spent some time looking at existing issues, and also debugging the related code for the sake of curiosity, and I figured out that there's an open issue (dominikh/go-tools#607) that mentions some cases, including that one specifically (instantiating structs - assignment of deprecated fields), and a PR that looks promising to fix it (dominikh/go-tools#1382).

So, I've pinged the linter's author as a reminder (noting that it worths taking a look, using the net.Dialer.DualStack example), and offered my help to get conflicts resolved on that PR's branch in order to get it ready to be reviewed (cause it seems a bit abandoned, and the PR author is marked as busy).

How did you catch it?

Apparently the IDE (linter?) is smarter/better at catching these than the staticcheck linter 🙈

[joanlopez]

Jfyi @codebien, as you asked, here's an update: dominikh/go-tools#1382

\ - hopefully it'll get fixed sooner rather than later! 💃🏻