Add a --emit stdout flag to scarb fmt

[ClementWalter]

Problem

There is no way to have scarb outputs the formatted result instead of overwriting the input.

This is a problem when integrating scarb with other linters in a tool like trunk.io. See this file using cairo-format:

https://github.com/ClementWalter/kakarot/blob/7686fbf022d99ce01927eb488ad59f0a0ec7ce5d/.trunk/trunk.yaml#L30

Proposed Solution

Add, like in the previous cairo-format tool, or in rustfmt a flag --emit stdout to emit and not overwrite

Notes

No response

[mkaput]

I'm all-in to do this the way how proposed solution looks like. I believe though that there is no such option upstream either, and one would have to also push a PR to Cairo compiler first.

I'm happy to accept PRs for this, as it's not something our team has capacity to take on immediately right now 😄

[ClementWalter]

created issue in cairo starkware-libs/cairo#4134

let's see what they are up to, imho just updating the behavior of --check is the easier

[orizi]

the handling of the output is done in the wrapping binary - not in the cairo library itself.
so there's no actual upstream updates required.

[Eikix]

I'd like to take this issue if possible

the handling of the output is done in the wrapping binary - not in the cairo library itself. so there's no actual upstream updates required.

I'm not sure I understand this, what is the "wrapping binary", are you referring to a part of Scarb's system?

After talking with @ClementWalter, I propose this change:

• Change scarb fmt --check outputting a file diff to output a new file altogether. This is in accordance with the Trunk documentation about custom linters and more generally with the rewrite norm of linting.

[mkaput]

• Change scarb fmt --check outputting a file diff to output a new file altogether. This is in accordance with the Trunk documentation about custom linters and more generally with the rewrite norm of linting.

I would definitely not deviate from rustfmt behaviour. It prints diffs so that the output is readable and actionable when somebody is reading CI logs. No reason to change that.

Please implement --emit stdout behaviour, like @ClementWalter suggested in the issue description.

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The issue is yours 😉 Thanks ♥️♥️♥️♥️♥️

[Eikix]

So if I understand correctly,
I should:

• inside scarb fmt related logic, add a flag "emit", with a single option "stdout" (for now).
• the emit flag with the option will emit a "target" file, fully formatted. with the option stdout, it'll emit it to stdout

-> no changes are made to cairo format
-> no changes are made to --check command

[mkaput]

Yep!