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

found build scripts with duplicate file stems, but all build

Error message

found build scripts with duplicate file stems, but all build scripts must have a unique file stem

What it means

Error "found build scripts with duplicate file stems, but all build scripts must have a unique file stem" thrown in rust-lang/cargo.

Source

Thrown at src/workspace/parser/targets.rs:928

            .file_stem()
            .and_then(|s| s.to_str())
            .expect("previously normalized");
        seen.entry(stem)
            .or_insert_with(Vec::new)
            .push(script.as_str());
    }
    let mut conflict_file_stem = false;
    let mut err_msg = String::from(
        "found build scripts with duplicate file stems, but all build scripts must have a unique file stem",
    );
    for (stem, paths) in seen {
        if paths.len() > 1 {
            conflict_file_stem = true;
            write!(&mut err_msg, "\n  for stem `{stem}`: {}", paths.join(", "))?;
        }
    }
    if conflict_file_stem {
        anyhow::bail!(err_msg);
    }
    Ok(())
}

fn configure(
    toml: &TomlTarget,
    target: &mut Target,
    target_kind_human: &str,
    warnings: &mut Vec<String>,
) -> CargoResult<()> {
    let t2 = target.clone();
    target
        .set_tested(toml.test.unwrap_or_else(|| t2.tested()))
        .set_doc(toml.doc.unwrap_or_else(|| t2.documented()))
        .set_doctest(toml.doctest.unwrap_or_else(|| t2.doctested()))
        .set_benched(toml.bench.unwrap_or_else(|| t2.benched()))
        .set_harness(toml.harness.unwrap_or_else(|| t2.harness()))
        .set_proc_macro(toml.proc_macro().unwrap_or_else(|| t2.proc_macro()))

View on GitHub (pinned to 0e07a15537)

Solutions

1. Rename one of the build script files so their file stems are unique.
2. Point `build = "..."` at distinct script paths for each package.

When it happens

Trigger: Thrown at src/workspace/parser/targets.rs:928 when the library encounters an invalid state.

Common situations: Occurs when multiple build scripts share the same file stem (e.g. `build.rs` and `build/main.rs` both stemming to `build`). Rename build script files so their stems are unique.

AI-assisted analysis of rust-lang/cargo@0e07a15537 (2026-08-06). Data as JSON: /data/errors/0a896bf0fae96852.json. Report an issue: GitHub.