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

found no binary in cargo output

Error message

found no binary in cargo output

What it means

Returned by build_get_binary when parsing cargo's --message-format=json output yields no compiler-artifact message with a non-null executable. The helper expects exactly one binary and errors if zero match (a separate error covers two).

Source

Thrown at src/tools/miri/miri-script/src/util.rs:215

            .args(&["--all-targets", "--message-format=json"]);
        let output = cmd.output()?;
        let mut bin = None;
        for line in output.stdout.lines() {
            let line = line?;
            if line.starts_with("{") {
                let json: serde_json::Value = serde_json::from_str(&line)?;
                if json["reason"] == "compiler-artifact"
                    && !json["profile"]["test"].as_bool().unwrap()
                    && !json["executable"].is_null()
                {
                    if bin.is_some() {
                        bail!("found two binaries in cargo output");
                    }
                    bin = Some(PathBuf::from(json["executable"].as_str().unwrap()))
                }
            }
        }
        bin.ok_or_else(|| anyhow!("found no binary in cargo output"))
    }

    pub fn check(
        &self,
        crate_dir: impl AsRef<OsStr>,
        features: &[String],
        args: &[String],
    ) -> Result<()> {
        self.cargo_cmd(crate_dir, "check", features).arg("--all-targets").args(args).run()?;
        Ok(())
    }

    pub fn doc(
        &self,
        crate_dir: impl AsRef<OsStr>,
        features: &[String],
        args: &[String],
    ) -> Result<()> {

View on GitHub (pinned to 7088e4b63a)

Solutions

1. Confirm the crate_dir actually defines a [[bin]] target with cargo metadata --no-deps.
2. Ensure features passed to build_get_binary enable (not disable) the binary target.
3. Run the same cargo build --message-format=json manually and grep for compiler-artifact + executable to see what cargo reports.
4. If the build failed, fix the underlying compile error first — no artifact is emitted on failure.

Example fix

// before
bin.ok_or_else(|| anyhow!("found no binary in cargo output"))

// after: include how many artifact lines were seen for diagnosis
bin.ok_or_else(|| {
    anyhow!("found no binary in cargo output \
             (saw {artifacts_seen} compiler-artifact lines, \
             {nontest_exec} with non-test executables)",
        artifacts_seen, nontest_exec)
})

// Confirm the crate exposes a bin target before building for a binary:
fn has_bin_target(crate_dir: &Path) -> bool {
    let o = std::process::Command::new("cargo")
        .args(["metadata", "--no-deps", "--format-version=1"])
        .current_dir(crate_dir).output();
    matches!(o, Ok(out) if String::from_utf8_lossy(&out.stdout).contains("\"kind\": [\"bin\"]")))
}

null

match util.build_get_binary(crate_dir, features) {
    Ok(bin) => Ok(bin),
    Err(e) if e.to_string().contains("found no binary") => {
        eprintln!("{crate_dir:?} has no bin target; point miri-script at a binary crate");
        Err(e)
    }
    Err(e) => Err(e),
}

When it happens

Trigger: Calling build_get_binary on a crate_dir whose cargo build produces no executable artifact — e.g. the crate is a library, a proc-macro, or all its targets are filtered out (test profile, or only examples/benches that the filter excludes). Also if the build failed silently upstream and emitted no artifact lines.

Common situations: Pointing miri-script at a lib crate instead of a binary crate; the binary lives in a workspace member not selected by the build; --all-targets produced only test artifacts which are skipped by the profile.test filter; a misconfigured feature flag that disables the bin target.

Related errors

• Cargo invocation has failed: ${err}
• No compilation artifacts
• Multiple compilation artifacts are not supported.
• no cargo executable found at `{}`
• Unable to parse transfer manifest

AI-assisted analysis of rust-lang/rust@7088e4b63a (2026-08-10). Data as JSON: /api/errors/6fe3d9b9f3fcae7b. Report an issue: GitHub.