Function format_combined_textconv_patch 

pub fn format_combined_textconv_patch(
    git_dir: &Path,
    config: &ConfigSet,
    odb: &Odb,
    path: &str,
    parent_trees: &[ObjectId],
    result_tree: &ObjectId,
    abbrev: usize,
    context: usize,
    use_cc_word: bool,
    use_textconv: bool,
) -> Option<String>

Combined text diff with textconv (two parents, single-file focus).