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

library target names cannot contain hyphens: {}

Error message

library target names cannot contain hyphens: {}

What it means

Error "library target names cannot contain hyphens: {}" thrown in rust-lang/cargo.

Source

Thrown at src/workspace/parser/targets.rs:1152

fn validate_build_name(build: &str) -> CargoResult<()> {
    if Path::new(build).file_stem().is_none() {
        anyhow::bail!("invalid `package.build` file name");
    }
    Ok(())
}

fn name_or_panic(target: &TomlTarget) -> &str {
    target
        .name
        .as_deref()
        .unwrap_or_else(|| panic!("target name is required"))
}

fn validate_lib_name(target: &TomlTarget, warnings: &mut Vec<String>) -> CargoResult<()> {
    validate_target_name(target, TARGET_KIND_HUMAN_LIB, TARGET_KIND_LIB, warnings)?;
    let name = name_or_panic(target);
    if name.contains('-') {
        anyhow::bail!("library target names cannot contain hyphens: {}", name)
    }

    Ok(())
}

fn validate_bin_name(bin: &TomlTarget, warnings: &mut Vec<String>) -> CargoResult<()> {
    validate_target_name(bin, TARGET_KIND_HUMAN_BIN, TARGET_KIND_BIN, warnings)?;
    let name = name_or_panic(bin).to_owned();
    if restricted_names::is_conflicting_artifact_name(&name) {
        anyhow::bail!(
            "the binary target name `{name}` is forbidden, \
                 it conflicts with cargo's build directory names",
        )
    }

    Ok(())
}

View on GitHub (pinned to 0e07a15537)

Solutions

1. Replace hyphens with underscores in the library target name.
2. Set `[lib] name` explicitly to a name without hyphens.

When it happens

Trigger: Thrown at src/workspace/parser/targets.rs:1152 when the library encounters an invalid state.

Common situations: Occurs when a `[lib]` target name contains hyphens. Replace hyphens with underscores, since library crate names must be valid Rust identifiers.

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/4400322375732fed.json. Report an issue: GitHub.