Describe the bug

If a path contains self, this keyword must be enclosed in braces:

use crate::lexer::{self}; // valid
use crate::lexer::self;   // invalid

rustfmt with imports_granularity = "Module" sometimes splits use statements so that invalid code like above is emitted.

To Reproduce

use crate::lexer::{self, tokens::TokenData};

rustfmt formats it like this:

use crate::lexer::self;
use crate::lexer::tokens::TokenData;

When formatting the file again, the ::self is removed.

Expected behavior

rustfmt should emit the following code without having to run it twice:

use crate::lexer;
use crate::lexer::tokens::TokenData;

Note that use crate::lexer; and use crate::lexer::{self}; are not actually equivalent: The latter only imports the lexer module, while the former looks in all namespaces, so it can import up to 3 items at once, e.g. a function, a module and a macro of the same name.

To make sure that the behaviour doesn't change, it needs to be formatted like so:

use crate::lexer::{self};
use crate::lexer::tokens::TokenData;

However, I would find this rather annoying, because of the way rust-analyzer handles auto-imports.

Meta

• rustfmt version: rustfmt 1.4.34-nightly (ea268b9 2021-01-28)
• From where did you install rustfmt?: rustup
• How do you run rustfmt: cargo fmt