fn lookup_char_pos(&self, pos: BytePos) -> Loc
fn span_to_lines(&self, sp: Span) -> FileLinesResult
fn span_to_string(&self, sp: Span) -> String
fn span_to_filename(&self, sp: Span) -> FileName
fn merge_spans(&self, sp_lhs: Span, sp_rhs: Span) -> Option<Span>