rust-lang/rust-analyzer · error

unexpected `\r`, only Unix-style line endings allowed

Error message

unexpected `\r`, only Unix-style line endings allowed

What it means

The ungrammar lexer rejects carriage-return characters outright: any `\r` in the input bails, because grammar files are expected to use Unix (LF) line endings only. This keeps position tracking and the parser simple and deterministic.

Source

Thrown at lib/ungrammar/src/lexer.rs:113

                }
            }
            TokenKind::Token(buf)
        }
        c if is_ident_char(c) => {
            let mut buf = String::new();
            buf.push(c);
            loop {
                match chars.clone().next() {
                    Some(c) if is_ident_char(c) => {
                        chars.next();
                        buf.push(c);
                    }
                    _ => break,
                }
            }
            TokenKind::Node(buf)
        }
        '\r' => bail!("unexpected `\\r`, only Unix-style line endings allowed"),
        c => bail!("unexpected character: `{}`", c),
    };

    *input = chars.as_str();
    Ok(res)
}

fn is_escapable(c: char) -> bool {
    matches!(c, '\\' | '\'')
}
fn is_whitespace(c: char) -> bool {
    matches!(c, ' ' | '\t' | '\n')
}
fn is_ident_char(c: char) -> bool {
    matches!(c, 'a'..='z' | 'A'..='Z' | '_')
}

View on GitHub (pinned to e8f7e90aa3)

Solutions

1. Convert the file to LF line endings (dos2unix or editor setting)
2. Add/update `.gitattributes` to force `*.ungrammar text eol=lf`
3. Set git `core.autocrlf=input` for this repo
4. Configure your editor to save LF for .ungrammar files

Example fix

# before (CRLF bytes)
Expr = 'foo'
# after (LF)
Expr = 'foo'

// normalize CRLF before parsing
let src = if src.contains('\r') {
    src.replace("\r\n", "\n").replace('\r', "\n")
} else { src.to_string() };

match ungrammar::Grammar::parse(&src) {
    Err(e) if e.to_string().contains('\\r') => {
        eprintln!("convert the grammar file to LF line endings: {e}")
    }
    r => r?,
}

When it happens

Trigger: Loading a `.ungrammar` file saved with CRLF (Windows) line endings; a tool or editor converting line endings; a git checkout with `core.autocrlf=true` on Windows.

Common situations: Cloning the repo on Windows with autocrlf enabled; editing grammar files in an editor configured for CRLF; committing files reformatted on Windows.

Related errors

• unclosed token literal
• invalid escape in token literal
• unexpected character: `{}`
• Token from lexer must be single char: token = {token:#?}
• Invalid name `{}`: {}

AI-assisted analysis of rust-lang/rust-analyzer@e8f7e90aa3 (2026-09-03). Data as JSON: /api/errors/3ac0b96b1ffee0c3. Report an issue: GitHub.