Dry-run functionality

[ozkriff]

Is something like --dry-run planned? Or rustfix will always require a VCS?

[killercup]

I'm not sure I understand. What would --dry-run do? Not change the files? Isn't that basically the same as doing cargo check instead of cargo fix, then?

[killercup]

Oh, and depending on your answer, this seems like an issue better suited for the cargo repository, as the cargo fix tool lives there (cf. https://github.com/rust-lang/cargo/issues?utf8=✓&q=is%3Aissue+label%3ACommand-fix+). This repo only contains the rustfix library.

[Manishearth]

It would print out a diff of what it _would_ change. with cargo check you still have to wonder about which suggestions would get applied, and how

…

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[ozkriff]

From the 1.29 blog post:

The compiler has an API for this, and it only suggests fixing lints that we’re confident recommend correct code.

As far as I understand, not all warnings showed by cargo check are fixed by rustfix.

[killercup]

Ah, I see, writing the diff is an interesting idea. In theory you can write it to a .patch file, too, then.

Do you want to open this issue on the cargo repo, @ozkriff? Otherwise I can do it (but you probably have some concrete idea and use cases you could describe, too).

[ozkriff]

Do you want to open this issue on the cargo repo, @ozkriff?

👍 Will do in a few minutes.

you probably have some concrete idea and use cases you could describe

Actually, no, I was just asked about this in the comments to russian translation of 1.29 announcement.

[ozkriff]

Done: rust-lang/cargo#6040

[Manishearth]

I think this library will also need support for doing all this without editing, no?

[killercup]

@Manishearth nah, all file handling is done in the cargo subcommand

[ehuss]

Closing in favor of rust-lang/cargo#6040.