Function find_only_subdir

tools/regen/src/csharp.rs:127–146

(dir: &Path)

}

fn find_only_subdir(dir: &Path) -> Result<PathBuf> {
    let mut subdirs = vec![];

    for entry in fs::read_dir(dir)? {
        let entry = entry?;
        if entry.file_type()?.is_dir() {
            subdirs.push(entry.path());
        }
    }

    match subdirs.as_slice() {
        [] => bail!("Could not find a restored versioned directory under {}", dir.display()),
        [only] => Ok(only.clone()),
        _ => bail!(
            "Expected exactly one restored versioned directory under {}, found {}",
            dir.display(),
            subdirs.len()
        ),
    }
}

fn copy_overlay_dir(src: &Path, dst: &Path) -> Result<()> {
    if !src.exists() {