Function real_span_map 

pub(crate) fn real_span_map<'db>(
    db: &'db dyn SourceDatabase,
    editioned_file_id: EditionedFileId,
) -> &'db RealSpanMap

This is an implementation detail of HirFileId::span_map. Outside this crate, use HirFileId::from(file_id).span_map(db) instead of real_span_map(db, file_id).