Add workaround for hidden outer attribute

Author: phansch

clippy_lints/src/attrs.rs

@@ -7,6 +7,7 @@ use rustc::ty::{self, TyCtxt};
 use semver::Version;
 use syntax::ast::{Attribute, AttrStyle, Lit, LitKind, MetaItemKind, NestedMetaItem, NestedMetaItemKind};
 use syntax::codemap::Span;
+use syntax_pos::{Pos};
 use utils::{in_macro, match_def_path, opt_def_id, paths, snippet_opt, span_lint, span_lint_and_then};
 
 /// **What it does:** Checks for items annotated with `#[inline(always)]`,
@@ -267,7 +268,7 @@ fn check_attrs(cx: &LateContext, span: Span, name: &Name, attrs: &[Attribute]) {
 
             if let Some(snippet) = snippet_opt(cx, attr_to_item_span) {
                 let lines = snippet.split('\n').collect::<Vec<_>>();
-                if lines.iter().filter(|l| l.trim().is_empty()).count() > 1 {
+                if lines.iter().filter(|l| l.trim().is_empty()).count() > 1 && !is_hidden_attr(attr) {
                     span_lint(
                         cx,
                         EMPTY_LINE_AFTER_OUTER_ATTR,
@@ -312,6 +313,10 @@ fn check_semver(cx: &LateContext, span: Span, lit: &Lit) {
     );
 }
 
+fn is_hidden_attr(attr: &Attribute) -> bool {
+    attr.span.lo().to_usize() == 0 && attr.span.hi().to_usize() == 0
+}
+
 fn is_word(nmi: &NestedMetaItem, expected: &str) -> bool {
     if let NestedMetaItemKind::MetaItem(ref mi) = nmi.node {
         mi.is_word() && mi.name() == expected