rust-lang/cargo · error · anyhow::Error

'{}' is not a valid artifact specifier

Error message

'{}' is not a valid artifact specifier

What it means

ArtifactKind::parse accepts exactly `bin`, `cdylib`, `staticlib`, or `bin:<name>`. Anything else falls through; it tries to strip a `bin:` prefix and, on failure, returns this error. Artifact specifiers appear in a dependency's `artifact = [...]` list (RFC 3452 DEP-cargo-artifacts), selecting which build artifacts to depend on.

Source

Thrown at src/workspace/dependency.rs:654

    pub fn as_str(&self) -> Cow<'static, str> {
        match *self {
            ArtifactKind::SelectedBinary(name) => format!("bin:{}", name.as_str()).into(),
            _ => self.crate_type().into(),
        }
    }

    pub fn parse(kind: &str) -> CargoResult<Self> {
        Ok(match kind {
            "bin" => ArtifactKind::AllBinaries,
            "cdylib" => ArtifactKind::Cdylib,
            "staticlib" => ArtifactKind::Staticlib,
            _ => {
                return kind
                    .strip_prefix("bin:")
                    .map(|bin_name| ArtifactKind::SelectedBinary(bin_name.into()))
                    .ok_or_else(|| {
                        anyhow::anyhow!("'{}' is not a valid artifact specifier", kind)
                    });
            }
        })
    }

    fn validate(kinds: Vec<ArtifactKind>) -> CargoResult<Vec<ArtifactKind>> {
        if kinds.iter().any(|k| matches!(k, ArtifactKind::AllBinaries))
            && kinds
                .iter()
                .any(|k| matches!(k, ArtifactKind::SelectedBinary(_)))
        {
            anyhow::bail!(
                "Cannot specify both 'bin' and 'bin:<name>' binary artifacts, as 'bin' selects all available binaries."
            );
        }
        let mut kinds_without_dupes = kinds.clone();
        kinds_without_dupes.sort();
        kinds_without_dupes.dedup();

View on GitHub (pinned to 0e07a15537)

Solutions

1. Use one of the valid kinds: `bin`, `cdylib`, `staticlib`, or `bin:<binary-name>`.
2. For a named binary use the `bin:` prefix: `artifact = ["bin:mybin"]`.
3. Remove typos/whitespace and check spelling against the RFC 3452 artifact list.

Example fix

# Cargo.toml before
[dependencies.mycrate]
artifact = ["dylib"]

# after
[dependencies.mycrate]
artifact = ["cdylib"]

fn validate_artifact_kind(kind: &str) -> Result<(), String> {
    match kind {
        "bin" | "cdylib" | "staticlib" => Ok(()),
        k if k.starts_with("bin:") && k.len() > 4 => Ok(()),
        other => Err(format!("'{other}' is not a valid artifact specifier; use bin | cdylib | staticlib | bin:<name>")),
    }
}

fn is_valid_artifact_kind(s: &str) -> bool {
    matches!(s, "bin" | "cdylib" | "staticlib")
        || (s.starts_with("bin:") && s.len() > 4)
}

match ArtifactKind::parse(kind) {
    Err(e) if e.to_string().contains("not a valid artifact specifier") => {
        eprintln!("use one of: bin, cdylib, staticlib, bin:<name>");
        return Err(e);
    }
    r => r,
}

When it happens

Trigger: Writing a Cargo.toml dependency with an artifact string that is not one of the recognized forms, e.g. `artifact = ['dylib']` (should be `cdylib`), `artifact = ['exe']`, `artifact = ['bin:']` (empty name), or a typo like `artifact = ['bins']`.

Common situations: Typing the artifact kind from memory (e.g. `dylib` instead of `cdylib`, `exe`/`binary` instead of `bin`); forgetting the `bin:` prefix when selecting a named binary (`artifact = ['mybin']`); trailing characters or whitespace.

Related errors

• Cannot specify both 'bin' and 'bin:<name>' binary artifacts,
• dependency `{}` in package `{}` requires a `{}` artifact to
• Deprecated dependency sections are unsupported: {}
• could not compile due to {error_count} previous target resol
• {manifest_key_name} `{}` does not appear to exist{}.

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/d828e9b48c94aa58.json. Report an issue: GitHub.