zed-industries/zed · error

valid regex

Error message

valid regex

What it means

LazyLock initializer for the Emacs modeline regex; the regex crate failed to compile the constant pattern `-\*-\s*(.+?)\s*-\*-`. Because the pattern is a compile-time constant written by developers, failure can only come from a regex crate version change altering syntax/limits — never from file content. The assert documents that the constant is known-valid.

Source

Thrown at crates/language/src/modeline.rs:79

    }

    Some(settings).filter(|s| s.has_settings())
}

fn parse_modelines(modelines: &[&str], settings: &mut ModelineSettings) {
    for line in modelines {
        parse_emacs_modeline(line, settings);
        // if emacs is set, do not check for vim modelines
        if settings.has_settings() {
            return;
        }
    }

    parse_vim_modelines(modelines, settings);
}

static EMACS_MODELINE_RE: LazyLock<Regex> =
    LazyLock::new(|| Regex::new(r"-\*-\s*(.+?)\s*-\*-").expect("valid regex"));

/// Parse Emacs-style modelines
/// Format: -*- mode: rust; tab-width: 4; indent-tabs-mode: nil; -*-
/// See Emacs (set-auto-mode)
fn parse_emacs_modeline(line: &str, settings: &mut ModelineSettings) {
    let Some(captures) = EMACS_MODELINE_RE.captures(line) else {
        return;
    };
    let Some(modeline_content) = captures.get(1).map(|m| m.as_str()) else {
        return;
    };
    for part in modeline_content.split(';') {
        parse_emacs_key_value(part, settings, true);
    }
}

/// Parse Emacs-style Local Variables block
///

View on GitHub (pinned to f4178619ac)

Solutions

1. Run the regex in a unit test (Regex::new on the same literal) to surface the compile error and adjust syntax
2. Pin the regex crate version if a SemVer-incompatible change introduced new syntax rules
3. Simplify the pattern if it exceeds default size limits

When it happens

Trigger: Thrown at crates/language/src/modeline.rs:79 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zed-industries/zed@f4178619ac (2026-08-20). Data as JSON: /api/errors/396be4b0fb6dfbc1. Report an issue: GitHub.