Rustfmt deletes comments in 'use {}'

[darakshan]

Describe the bug

To Reproduce
run rustfmt on the following code:

use {std::env::args /* this comment gets removed */};
fn main() {println!("hello from {}!", args().next().unwrap());}

Expected behavior

comment should be preserved

Meta

• rustfmt version: rustfmt 1.4.30-stable (8c6769d 2021-01-18)
• From where did you install rustfmt? :rustup
• How do you run rustfmt: Cargo-fmt and VScode

[kangalio]

Here's a slightly more common example of where this bug results in an annoyance:

pub use serenity::model::{
	// channel::{Message, Reaction, ReactionType},
	// gateway::Ready,
	// guild::{Member, Role},
	// id::{ChannelId, GuildId, MessageId, RoleId, UserId},
	// permissions::Permissions,
	prelude::*,
	// user::User,
};

Upon invoking rustfmt, all the commented-out lines disappeared

[karyon]

repro'd with 1.4.38

[AndrewKvalheim]

Is this the same as #3984?

[ytmimi]

@AndrewKvalheim it seems like they are the same. Thanks for pointing that out 😁