rust-lang/cargo · error

invalid package name

Error message

invalid package name `{}`: it is a Rust keyword{}

What it means

`restricted_names::is_keyword` returns true for any of Rust's reserved keywords (`fn`, `crate`, `impl`, `match`, `async`, etc.). Cargo forbids these as package names because they collide with the language grammar and would break `use`/`extern crate` references. The bail appends `bin_help()` showing how to keep a binary by that logical name via `[[bin]]`.

Solutions

1. Pick a non-keyword name: suffix/prefix it, e.g. `match-tool`, `my_async`, `learn-trait`.
2. Keep the binary's logical name but use a valid package name plus `[[bin]] name = "match"` in Cargo.toml (as the help text shows), or place it at `src/bin/match.rs`.
3. Consult the keyword list (https://doc.rust-lang.org/reference/keywords.html) when choosing names.

Example fix

# before
$ cargo new match   # error: Rust keyword

# after
$ cargo new match-tool
# Cargo.toml — keep binary named "match" if desired:
# [[bin]]
# name = "match"
# path = "src/main.rs"

const KEYWORDS: &[&str] = &["Self","abstract","as","async","await","become","box","break","const","continue","crate","do","dyn","else","enum","extern","false","final","fn","for","if","impl","in","let","loop","macro","match","mod","move","mut","override","priv","pub","ref","return","self","static","struct","super","trait","true","try","type","typeof","unsafe","unsized","use","virtual","where","while","yield"];
fn is_keyword(name: &str) -> bool { KEYWORDS.contains(&name) }

fn is_non_keyword_name(name: &str) -> bool { !is_keyword(name) }

When it happens

Trigger: `cargo new fn`, `cargo init --name match`, `cargo new --name crate mytool`, or any name matching the keyword list in `restricted_names.rs`.

Common situations: Creating a tutorial/example crate named after a concept (`match`, `async`, `trait`). Auto-generating from a directory literally named `test`-adjacent keywords. Tooling that derives crate names from filenames matching keywords.

Related errors

• {err}{help}
• invalid package name
• invalid package name `test`: it conflicts with Rust's…
• invalid package name
• can't specify both lib and binary outputs

AI-assisted analysis of rust-lang/cargo@98a09e7e7d (2026-08-11). Data as JSON: /api/errors/8ed455a1939b8af1. Report an issue: GitHub.

Appendix: source

Thrown at src/ops/cargo_new.rs:159

                This can be done by setting the binary filename to `src/bin/{name}.rs` \
                or change the name in Cargo.toml with:\n\
                \n    \
                [[bin]]\n    \
                name = \"{name}\"\n    \
                path = \"src/main.rs\"\n\
            ",
                name = name
            ));
        }
        help
    };
    PackageName::new(name).map_err(|err| {
        let help = bin_help();
        anyhow::anyhow!("{err}{help}")
    })?;

    if restricted_names::is_keyword(name) {
        anyhow::bail!(
            "invalid package name `{}`: it is a Rust keyword{}",
            name,
            bin_help()
        );
    }
    if restricted_names::is_conflicting_artifact_name(name) {
        if has_bin {
            anyhow::bail!(
                "invalid package name `{}`: \
                it conflicts with cargo's build directory names{}",
                name,
                name_help
            );
        } else {
            shell.warn(format!(
                "package `{}` will not support binary \
                executables with that name, \
                it conflicts with cargo's build directory names",

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