Function rustc_mir::util::spanview::write_span

fn write_span<'tcx, W>(
    tcx: TyCtxt<'tcx>, 
    span: Span, 
    span_viewable: Option<&SpanViewable>, 
    alt: bool, 
    layer: usize, 
    w: &mut W
) -> Result<BytePos> where
    W: Write,