New lint for issue

#72

src/attrs.rs

@@ -0,0 +1,48 @@
+/// checks for attributes
+
+use rustc::plugin::Registry;
+use rustc::lint::*;
+use syntax::ast::*;
+use syntax::ptr::P;
+use syntax::codemap::Span;
+use syntax::parse::token::InternedString;
+
+declare_lint! { pub INLINE_ALWAYS, Warn,
+    "#[inline(always)] is usually a bad idea."}
+
+
+#[derive(Copy,Clone)]
+pub struct AttrPass;
+
+impl LintPass for AttrPass {
+    fn get_lints(&self) -> LintArray {
+        lint_array!(INLINE_ALWAYS)
+    }
+    
+    fn check_item(&mut self, cx: &Context, item: &Item) {
+		check_attrs(cx, &item.ident, &item.attrs)
+	}
+    
+    fn check_impl_item(&mut self, cx: &Context, item: &ImplItem) { 
+		check_attrs(cx, &item.ident, &item.attrs)
+	}
+        
+	fn check_trait_item(&mut self, cx: &Context, item: &TraitItem) {
+		check_attrs(cx, &item.ident, &item.attrs)
+	}
+}
+
+fn check_attrs(cx: &Context, ident: &Ident, attrs: &[Attribute]) {
+	for attr in attrs {
+		if let MetaList(ref inline, ref values) = attr.node.value.node {
+			if values.len() != 1 || inline != &"inline" { continue; }
+			if let MetaWord(ref always) = values[0].node {
+				if always != &"always" { continue; }
+				cx.span_lint(INLINE_ALWAYS, attr.span, &format!(
+					"You have declared #[inline(always)] on {}. This \
+					is usually a bad idea. Are you sure?", 
+					ident.as_str()));
+			}
+		}
+	}
+}

src/lib.rs

@@ -24,6 +24,7 @@ pub mod eta_reduction;
 pub mod identity_op;
 pub mod mut_mut;
 pub mod len_zero;
+pub mod attrs;
 
 #[plugin_registrar]
 pub fn plugin_registrar(reg: &mut Registry) {
@@ -44,6 +45,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
     reg.register_lint_pass(box mut_mut::MutMut as LintPassObject);
     reg.register_lint_pass(box len_zero::LenZero as LintPassObject);
     reg.register_lint_pass(box misc::CmpOwned as LintPassObject);
+    reg.register_lint_pass(box attrs::AttrPass as LintPassObject);
     
     reg.register_lint_group("clippy", vec![types::BOX_VEC, types::LINKEDLIST,
                                            misc::SINGLE_MATCH, misc::STR_TO_STRING,
@@ -60,5 +62,6 @@ pub fn plugin_registrar(reg: &mut Registry) {
                                            mut_mut::MUT_MUT,
                                            len_zero::LEN_ZERO,
                                            len_zero::LEN_WITHOUT_IS_EMPTY,
+                                           attrs::INLINE_ALWAYS,
                                            ]);
 }

tests/compile-fail/attrs.rs

@@ -0,0 +1,12 @@
+#![feature(plugin)]
+#![plugin(clippy)]
+
+#[deny(inline_always)]
+#[inline(always)] //~ERROR You have declared #[inline(always)] on test_attr_lint.
+fn test_attr_lint() {
+	assert!(true)
+}
+
+fn main() {
+	test_attr_lint()
+}