Rustfmt: [unstable option] imports_layout

[scampi]

Tracking issue for unstable option: imports_layout

[jimmycuadra]

What's necessary to stabilize this?

[scampi]

There are some steps described in https://github.com/rust-lang/rustfmt/blob/master/Processes.md#stabilising-an-option.
https://github.com/rust-lang/rustfmt/pull/3581 is an attempt at this.

[mzabaluev]

Why does Horizontal have to exceed max_width?
How does this behavior interact with merge_imports = true?

I think it should be possible to try to fit all import statements into max_width, replicating the path prefix for any spill-over items into the next line(s).

[mzabaluev]

One good reason to prefer the Horizontal layout (and stabilize this setting after the behavioral aspects are ironed out) is to keep the imports searchable with grep-like tools that don't easily match across multiple lines.

[andreastt]

A counter-argument for Vertical sorting is that it makes rebases significantly easier.

I recently had to do a rebase of a fairly complicated refactoring that moved lots of types around, and git rebase tools for in-line changes is not great.

I would like to use this feature in mozilla-central once it’s stablised.

[vn971]

I would love independent imports:

use foo::{
    aaaaaaaaaaaaaaaaaa, bbbbbbbbbbbbbbbbbb, cccccccccccccccccc, dddddddddddddddddd,
    eeeeeeeeeeeeeeeeee, ffffffffffffffffff,
};

=>

use foo::aaaaaaaaaaaaaaaaaa;
use foo::bbbbbbbbbbbbbbbbbb;
use foo::cccccccccccccccccc;
use foo::dddddddddddddddddd;
use foo::eeeeeeeeeeeeeeeeee;
use foo::ffffffffffffffffff;

As a possible alternative, I find this style super-friendly to git, immediately readable to my tastes, easy to play around with commenting-uncommenting.

Is it possible to have it as an independent alternative option?

[dtolnay]

I think "independent imports" (https://github.com/rust-lang/rustfmt/issues/3361#issuecomment-632661079) is outside of what this option is for, and is a discussion for https://github.com/rust-lang/rustfmt/issues/3362 instead. It's already been brought up there in https://github.com/rust-lang/rustfmt/issues/3362#issuecomment-641125438.

AIUI the two options are orthogonal and the distinction is as follows: you can think of merge_imports as determining the tokens of our imports i.e. how/whether they should be grouped i.e. which parts of which specific paths should go inside of the same curly braces; while imports_layout determines the whitespace of each import after the point that the tokens have already been decided.

[Lokathor]

Shouldn't "mixed' be called "compressed" to match other similar options?