Handle Windows newlines gracefully

[g-andrade]

Bug Description

Recently I tried to run CI for my lib on Windows.

All the tests passed (surprisingly!) but Elvis (invoked through rebar3_lint) complained a lot about trailing spaces and operator spaces. Like, for almost every line of code.

So, what's happening is: git can be configured to automatically convert line endings into whatever the OS's native ones are.

And that's what it does by default on the Windows image I used, apparently.

However, elvis_core only knows how to split lines using \n (e.g. here, which leaves all of those extra \r around (and they qualify as whitespace.)

To Reproduce

Now that's tricky 🤔 I don't have Windows myself.

But it boils down to:

1. clone a rebar3 project which integrates rebar3_lint on Windows, and
2. run rebar3 lint.

Alternatively, leveraging GitHub Actions for CI'ing on Windows should be enough to confirm the problem.

Expected Behavior

I expected that any newline-affected rules (e.g. no_trailing_whitespace) would take into account Windows newline endings gracefully (\r\n rather than just \n.)

rebar3 Logs

Here it is (let me know if more details are needed.)

Additional Context

• OS: Microsoft Windows Server 2019 (10.0.17763)
• Erlang version: OTP 24.0.5
• rebar3 version: 3.16.1
• rebar3_lint version: 0.5.0 (which imports elvis_core 1.2.0)

[g-andrade]

By the way: in the process of investigating the issue I pretty much fixed it, so let me know and I can open a PR (which I didn't do already because at some point I read CONTRIBUTING.md 😄 )

[g-andrade]

Here's the fix and here's confirmation that it worked.

If you agree with the solution, I'll open a PR.

If not, I'm open to exploring other options (and I'll understand if you don't even consider this a real problem, given how few people are actually using Windows to develop Erlang.)

[elbrujohalcon]

@g-andrade Great catch! Amazing description! Incredibly thorough explanation! And perfect fix!

I would ❤️ to have that as a PR 🙏🏻