Hmbown/CodeWhale · error · anyhow::Error

Patch is empty.

Error message

Patch is empty.

What it means

run_apply reads the patch from --patch-file or stdin and refuses it before invoking git when the content is empty after trimming. It is an input guard: an all-whitespace patch is always a caller mistake (bad pipe, wrong file, empty model output), and applying it would be a no-op at best.

Source

Thrown at crates/tui/src/lib.rs:8419

    } else {
        "working-tree".to_string()
    };
    if let Some(path) = &args.path {
        label.push(' ');
        label.push_str(path.to_string_lossy().as_ref());
    }
    label
}

fn run_apply(args: ApplyArgs) -> Result<()> {
    let patch = if let Some(path) = args.patch_file {
        std::fs::read_to_string(&path)
            .map_err(|e| anyhow::anyhow!("Failed to read patch {}: {}", path.display(), e))?
    } else {
        read_patch_from_stdin()?
    };
    if patch.trim().is_empty() {
        bail!("Patch is empty.");
    }

    let mut tmp = NamedTempFile::new()?;
    tmp.write_all(patch.as_bytes())?;
    let tmp_path = tmp.path().to_path_buf();

    let output = crate::dependencies::Git::command()
        .ok_or_else(|| anyhow::anyhow!("git not found on PATH"))?
        .arg("apply")
        .arg("--whitespace=nowarn")
        .arg(&tmp_path)
        .output()
        .map_err(|e| anyhow::anyhow!("Failed to run git apply: {e}"))?;

    if !output.status.success() {
        let stderr = String::from_utf8_lossy(&output.stderr);
        bail!("git apply failed: {}", stderr.trim());
    }

View on GitHub (pinned to 0c42157ee5)

Solutions

1. Inspect the file: `wc -c patch.diff` and `head patch.diff`
2. Regenerate the patch at its source (re-run the tool/model that produced it)
3. If piping, check the producer's exit status and output before applying
4. Confirm the path is a file, not a directory or wrong name

Example fix

# before
codewhale apply --patch-file empty.diff   # Patch is empty.

# after
[ -s patch.diff ] || { echo 'producer wrote nothing'; exit 1; }
codewhale apply --patch-file patch.diff

[ -s "$PATCH" ] && [ -n "$(tr -d '[:space:]' < "$PATCH")" ] || { echo "patch '$PATCH' is empty"; exit 1; }

if let Err(e) = run_apply(args) {
    if e.to_string().contains("Patch is empty") {
        // regenerate at the source; do not retry the same input
    }
}

When it happens

Trigger: --patch-file points at an empty or whitespace-only file; stdin piped from a producer that wrote nothing; the model/tool upstream returned an empty diff block that was saved to disk.

Common situations: LLM answered with prose instead of a diff and the pipeline saved the empty fenced block; upstream generate step failed silently because the script lacks `set -e`; truncated download or wrong file path.

Related errors

• git apply failed: {}
• No patch file provided and stdin is empty.
• host cannot be empty
• continual harness entry id cannot be empty
• Agent Mail accepts a bounded handoff summary, not a raw tran

AI-assisted analysis of Hmbown/CodeWhale@0c42157ee5 (2026-08-20). Data as JSON: /api/errors/79e70e586e6e482a. Report an issue: GitHub.