factor out is_automatically_derived util fn

clippy_lints/src/utils/inspector.rs

@@ -4,7 +4,8 @@
 
 use rustc::lint::*;
 use rustc::hir;
-use syntax::ast::{Attribute, MetaItemKind};
+use syntax::ast::Attribute;
+use syntax::attr;
 
 /// **What it does:** Dumps every ast/hir node which has the `#[clippy_dump]` attribute
 ///
@@ -128,10 +129,7 @@ impl LateLintPass for Pass {
 }
 
 fn has_attr(attrs: &[Attribute]) -> bool {
-    attrs.iter().any(|attr| match attr.node.value.node {
-        MetaItemKind::Word(ref word) => word == "clippy_dump",
-        _ => false,
-    })
+    attr::contains_name(attrs, "clippy_dump")
 }
 
 fn print_decl(cx: &LateContext, decl: &hir::Decl) {

clippy_lints/src/utils/mod.rs

@@ -14,6 +14,7 @@ use std::env;
 use std::mem;
 use std::str::FromStr;
 use syntax::ast::{self, LitKind};
+use syntax::attr;
 use syntax::codemap::{ExpnFormat, ExpnInfo, MultiSpan, Span, DUMMY_SP};
 use syntax::errors::DiagnosticBuilder;
 use syntax::ptr::P;
@@ -761,3 +762,8 @@ pub fn is_refutable(cx: &LateContext, pat: &Pat) -> bool {
         }
     }
 }
+
+/// Checks for the `#[automatically_derived]` attribute all `#[derive]`d implementations have.
+pub fn is_automatically_derived(attrs: &[ast::Attribute]) -> bool {
+    attr::contains_name(attrs, "automatically_derived")
+}