rust-lang/cargo · error

missing crate name for `@{v}`

Error message

missing crate name for `@{v}`

What it means

In resolve_crate (yank.rs:57-60), when the crate argument starts with `@` (i.e. split_once('@') yields an empty left side), the crate name is missing. By Cargo convention a leading `@` denotes a response file, so a bare `@version` is treated as a crate-less spec and rejected.

Source

Thrown at src/bin/cargo/commands/yank.rs:59

        version.map(|s| s.to_string()),
        args.get_one::<String>("token").cloned().map(Secret::from),
        args.registry_or_index(gctx)?,
        args.flag("undo"),
    )?;
    Ok(())
}

fn resolve_crate<'k>(
    mut krate: Option<&'k str>,
    mut version: Option<&'k str>,
) -> crate::CargoResult<(Option<&'k str>, Option<&'k str>)> {
    if let Some((k, v)) = krate.and_then(|k| k.split_once('@')) {
        if version.is_some() {
            anyhow::bail!("cannot specify both `@{v}` and `--version`");
        }
        if k.is_empty() {
            // by convention, arguments starting with `@` are response files
            anyhow::bail!("missing crate name for `@{v}`");
        }
        krate = Some(k);
        version = Some(v);
    }

    if let Some(version) = version {
        semver::Version::parse(version).with_context(|| {
            if let Some(stripped) = version.strip_prefix("v") {
                return format!(
                    "the version provided, `{version}` is not a \
                    valid SemVer version\n\n\
                    help: try changing the version to `{stripped}`",
                );
            }
            format!("invalid version `{version}`")
        })?;
    }

View on GitHub (pinned to 0e07a15537)

Solutions

1. Provide the crate name: `cargo yank mycrate@1.2.3` or `cargo yank mycrate --version 1.2.3`.
2. If you intended a response file, use a real `@file` argument to a subcommand that supports it — `yank` does not.

Example fix

// before
$ cargo yank @1.2.3
error: missing crate name for `@1.2.3`

// after
$ cargo yank mycrate@1.2.3

if let Some(spec) = &crate_arg {
    if spec.starts_with('@') {
        return Err("missing crate name before @; use crate@version");
    }
}

fn has_crate_before_at(spec: &str) -> bool {
    match spec.split_once('@') {
        Some((k, _)) => !k.is_empty(),
        None => true,
    }
}

When it happens

Trigger: Running `cargo yank @1.2.3` (version given but no crate name before the `@`).

Common situations: Forgetting the crate name; assuming `--version` style works positionally as `@version`; shell expansion that dropped the crate token.

Related errors

• cannot specify both `@{v}` and `--version`
• {}
• "--package <SPEC>" requires a SPEC format value. Run `cargo
• argument for --color must be auto, always, or never, but fou
• subcommand is required, add a subcommand to the command alia

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/229c881deea2421d.json. Report an issue: GitHub.