Function doc_lines 

fn doc_lines(attrs: &[Attribute]) -> Vec<DocLine>

The lines of every string-literal doc attribute in attrs, in order.

Non-doc attributes are skipped, so an interleaved #[cfg(...)] never interrupts a tag (#613). A #[doc = include_str!(..)] is not a literal and stays unread. Per attribute:

• a single-line literal (each /// line, a #[doc = "..."] from macro_rules!) loses at most the one leading space rustdoc’s /// puts there;
• a multi-line literal (/** ... */, #[doc = "a\nb"]) loses the common leading whitespace of its non-blank lines, so a relative indent survives;
• a whitespace-only line becomes an empty one.