Function parse_detached_item 

pub(crate) fn parse_detached_item(cx: &mut ParseCtxt<'_>) -> ParseResult<Item>

 ⟨specs⟩ ::= ⟨fn-spec⟩
           | ⟨struct-spec⟩
           | ⟨enum-spec⟩
           | ⟨mod⟩
           | ⟨impl⟩