Function build_file_diffs 

pub fn build_file_diffs(
    odb: &Odb,
    entries: Vec<DiffEntry>,
    detail: DiffDetail,
    diff_options: DiffOptions,
    config: &ConfigSet,
    thread_policy: &ThreadPolicy,
) -> Result<DiffFilesOutput>

Fill per-file diff bodies for tree/index diff entries.

Name-only and name-status skip blob reads for line diffs; stat loads blobs for counts only; patch runs the full structured line engine.

Errors

Propagates object database and parallel diff errors.