rustc: Introduce a lang_items pass, part of coherence and operator overloading.

This will also help us remove kinds.

src/rustc/metadata/csearch.rs

@@ -25,6 +25,7 @@ export get_enum_variants;
 export get_impls_for_mod;
 export get_trait_methods;
 export get_method_names_if_trait;
+export get_item_attrs;
 export each_path;
 export get_type;
 export get_impl_traits;
@@ -149,6 +150,14 @@ fn get_method_names_if_trait(cstore: cstore::cstore, def: ast::def_id)
     ret decoder::get_method_names_if_trait(cdata, def.node);
 }
 
+fn get_item_attrs(cstore: cstore::cstore,
+                  def_id: ast::def_id,
+                  f: fn(~[@ast::meta_item])) {
+
+    let cdata = cstore::get_crate_data(cstore, def_id.crate);
+    decoder::get_item_attrs(cdata, def_id.node, f)
+}
+
 fn get_class_fields(tcx: ty::ctxt, def: ast::def_id) -> ~[ty::field_ty] {
     let cstore = tcx.cstore;
     let cdata = cstore::get_crate_data(cstore, def.crate);

src/rustc/metadata/decoder.rs

@@ -39,6 +39,7 @@ export get_crate_vers;
 export get_impls_for_mod;
 export get_trait_methods;
 export get_method_names_if_trait;
+export get_item_attrs;
 export get_crate_module_paths;
 export def_like;
 export dl_def;
@@ -659,6 +660,18 @@ fn get_method_names_if_trait(cdata: cmd, node_id: ast::node_id)
     ret some(resulting_method_names);
 }
 
+fn get_item_attrs(cdata: cmd,
+                  node_id: ast::node_id,
+                  f: fn(~[@ast::meta_item])) {
+
+    let item = lookup_item(node_id, cdata.data);
+    do ebml::tagged_docs(item, tag_attributes) |attributes| {
+        do ebml::tagged_docs(attributes, tag_attribute) |attribute| {
+            f(get_meta_items(attribute));
+        }
+    }
+}
+
 // Helper function that gets either fields or methods
 fn get_class_members(cdata: cmd, id: ast::node_id,
                      p: fn(char) -> bool) -> ~[ty::field_ty] {

src/rustc/metadata/encoder.rs

@@ -759,6 +759,7 @@ fn encode_info_for_item(ecx: @encode_ctxt, ebml_w: ebml::writer, item: @item,
         encode_type_param_bounds(ebml_w, ecx, tps);
         encode_type(ecx, ebml_w, node_id_to_type(tcx, item.id));
         encode_name(ebml_w, item.ident);
+        encode_attributes(ebml_w, item.attrs);
         let mut i = 0u;
         for vec::each(*ty::trait_methods(tcx, local_def(item.id))) |mty| {
             alt ms[i] {