build_discrete_facet_label_expr (src/writer/vegalite/mod.rs:964) is reached from apply_facet_label_renaming only when index_map is empty and the scale is not binned. Facet ordering converts every discrete facet column to integer sort indices and routes it through build_indexed_facet_label_expr instead, so that combination no longer occurs — the branch at src/writer/vegalite/mod.rs:744 looks dead.
build_discrete_facet_label_expr(src/writer/vegalite/mod.rs:964) is reached fromapply_facet_label_renamingonly whenindex_mapis empty and the scale is not binned. Facet ordering converts every discrete facet column to integer sort indices and routes it throughbuild_indexed_facet_label_exprinstead, so that combination no longer occurs — the branch atsrc/writer/vegalite/mod.rs:744looks dead.