Add rustfmt rules to the project.

[xgreenx]

Added rustfmt rules. I used my favorite rules but we can discuss your wishes=)
It requires usage of nightly rustfmt because it contains many new configurations.
Formatted the whole project, so it will make ongoing PR harder(you need to fix conflicts)
Added CI to check the fmt.

[xgreenx]

You can check what the code looks like and decide whether it is okay or not=)
And maybe better to merge other PR first before this one.

[xgreenx]

We actually can remove it because it is very fas check(~10 seconds) =)

[adlerjohn]

We actually had a custom rustfmt config, then removed it in #22. Generally, using any config that isn't the default is a bit iffy, since it invites bikeshedding: some people prefer one thing, other prefer another. By keeping everything at default as a rule, there's no bikeshedding possible on individual preferences.

[vlopes11]

I think its a good thing to have a fmt standard. But then if we are diverging from the default of rustfmt, we might want to enforce that to all our repos so we don't end up having different styles across the org

[vlopes11]

Won't reducing from the default 100 to 90 cause a lot of wrapping? I already feel a bit constrained with the default 100, also considering that almost everyone uses wide screens

[xgreenx]

I'm using only a laptop=) The default value is 120. I didn't try 100 by I know that with 90, it always fits into GitHub split mode review=)

[leviathanbeak]

the default value is 100 -> https://rust-lang.github.io/rustfmt/?version=v1.5.1&search=#max_width

[vlopes11]

That is cool, but isn't stable yet:

rust-lang/rustfmt#3350

[xgreenx]

Many fields from here are unstable=) It is why it is nightly rust fmt

[adlerjohn]

Hmmm. Does this require users to switch between nightly and stable to run cargo fmt? The codebase itself builds with stable.

[xgreenx]

They need to do cargo +nightly fmt. But all IDE support a separate channel for rustfmt.

[vlopes11]

I personally prefer Module. Things get a bit confusing, maybe even unreadable, if we have multiple nested levels - whereas they are most of the times just single lines if its per module

https://rust-lang.github.io/rustfmt/?version=v1.5.1&search=#Module%5C%3A

[xgreenx]

Example from our codebase("Crate"):

Example from our codebase("Module"):

I'm okay with both variants but prefer more "Crate" because I can easy collapse imports from one crate or add a cfg flag for whole crate=)

[Voxelot]

the cfg flag can go both ways. For example, it is also likely that a cfg flag will affect a subset of imports within a crate, rather than the entire crate.

use crate::{ThingA, ThingB}
#[cfg(feature = "feature-c")]
use crate::ThingC

Will rustfmt avoid collapsing the import if we have a cfg flag on a specific set of imports from a crate?

[xgreenx]

Yes, it will not touch cfg imports. Also, if you have an "enter" between to import section, it will not merge them into one, but it will collapse and sort all inside each section(the same for cfg).

Example with "enter":

Example without "enter":

[vlopes11]

This one is very good

[vlopes11]

This is cool too, but try is so old that we don't even see it anymore. Anyway, its definitely something we should have

[xgreenx]

I think its a good thing to have a fmt standard. But then if we are diverging from the default of rustfmt, we might want to enforce that to all our repos so we don't end up having different styles across the org

Yea, if we are okay to apply rustfmt for fuel-core then better to do the same for all rust repos=)

[adlerjohn]

If this requires an org-wide change then it should have org-wide buy-in. Might be time to follow-up on FuelLabs/rfcs#8

[leviathanbeak]

Reviewed all the config options, apart from maybe imports_granularity = "Crate/Module" I don't see much use in enforcing other ones, that is, diverging from the default values.

[Voxelot]

lgtm, but since this is a big change plz wait for at least one other approval before merging.

[Dentosal]

lgtm as well

[Voxelot]

@adlerjohn we need to update the ci requirements on the repo to merge this pr

[Voxelot]

@xgreenx can you also update CONTRIBUTING.md with the updated instructions for running the nightly formatter?