Add get_line confusable to Stdin::read_line()

[JakenHerman]

This pull request resolves rust-lang#131091

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I've updated tests for tests/ui/attributes/rustc_confusables_std_cases in order to verify this change is working as intended.

[myclevorname]

Thank you for doing this.

[GrigorenkoPV]

You opened the PR in the wrong repository, you should do it here instead.

Also I think a test case should be added in tests/ui/attributes/rustc_confusables_std_cases.rs

[JakenHerman]

@GrigorenkoPV Yea, I didn't do it to the rust repository yet because I was still adding tests 😄 I've never added one of these tests, the strategy seems straight forward, but I don't know how to determine that error code that's in the comments. (i.e. //~ERROR E0599)

Edit: Actually, after running rustic --explain E0599, I believe this is the error code that I want.

So I've added:

let mut buffer = String::new();
let stdin = std::io::stdin();
stdin.get_line(&mut buffer).unwrap(); //~ ERROR E0599
//~^ HELP you might have meant to use `read_line`

I've run ./x.py build followed by ./x.py test tests/ui/attributes/rustc_confusables_std_cases.rs, but my tests are failing, so I'm not sure what's going on.. Sorry - first time working on this project, I'll get it worked out before I PR into the rust repository.

Edit (again): I see, my expected output was incorrect.. about to modify PR to target main repository.