Auto merge of #34842 - cgswords:attr_enc, r=nrc

Better attribute and metaitem encapsulation throughout the compiler

This PR refactors most (hopefully all?) of the `MetaItem` interactions outside of `libsyntax` (and a few inside) to interact with MetaItems through the provided traits instead of directly creating / destruct / matching against them. This is a necessary first step to eventually converting `MetaItem`s to internally use `TokenStream` representations (which will make `MetaItem` interactions much nicer for macro writers once the new macro system is in place).

r? @nrc

3 files changed, 24 insertions, 35 deletions

diff --git a/src/librustc_metadata/decoder.rs b/src/librustc_metadata/decoder.rs
index 409cec282bc..63345a15e6a 100644
--- a/src/librustc_metadata/decoder.rs
+++ b/src/librustc_metadata/decoder.rs
@@ -1160,15 +1160,7 @@ fn get_attributes(md: rbml::Doc) -> Vec<ast::Attribute> {
                 // an attribute
                 assert_eq!(meta_items.len(), 1);
                 let meta_item = meta_items.into_iter().nth(0).unwrap();
-                codemap::Spanned {
-                    node: ast::Attribute_ {
-                        id: attr::mk_attr_id(),
-                        style: ast::AttrStyle::Outer,
-                        value: meta_item,
-                        is_sugared_doc: is_sugared_doc,
-                    },
-                    span: syntax_pos::DUMMY_SP
-                }
+                attr::mk_doc_attr_outer(attr::mk_attr_id(), meta_item, is_sugared_doc)
             }).collect()
         },
         None => vec![],
diff --git a/src/librustc_metadata/encoder.rs b/src/librustc_metadata/encoder.rs
index c896263de94..732c256a191 100644
--- a/src/librustc_metadata/encoder.rs
+++ b/src/librustc_metadata/encoder.rs
@@ -44,7 +44,7 @@ use std::rc::Rc;
 use std::u32;
 use syntax::abi::Abi;
 use syntax::ast::{self, NodeId, Name, CRATE_NODE_ID, CrateNum};
-use syntax::attr;
+use syntax::attr::{self,AttrMetaMethods,AttributeMethods};
 use errors::Handler;
 use syntax;
 use syntax_pos::BytePos;
@@ -1431,31 +1431,28 @@ fn encode_item_index(rbml_w: &mut Encoder, index: IndexData) {
 }
 
 fn encode_meta_item(rbml_w: &mut Encoder, mi: &ast::MetaItem) {
-    match mi.node {
-      ast::MetaItemKind::Word(ref name) => {
+    if mi.is_word() {
+        let name = mi.name();
         rbml_w.start_tag(tag_meta_item_word);
-        rbml_w.wr_tagged_str(tag_meta_item_name, name);
+        rbml_w.wr_tagged_str(tag_meta_item_name, &name);
         rbml_w.end_tag();
-      }
-      ast::MetaItemKind::NameValue(ref name, ref value) => {
-        match value.node {
-          ast::LitKind::Str(ref value, _) => {
-            rbml_w.start_tag(tag_meta_item_name_value);
-            rbml_w.wr_tagged_str(tag_meta_item_name, name);
-            rbml_w.wr_tagged_str(tag_meta_item_value, value);
-            rbml_w.end_tag();
-          }
-          _ => {/* FIXME (#623): encode other variants */ }
-        }
-      }
-      ast::MetaItemKind::List(ref name, ref items) => {
+    } else if mi.is_value_str() {
+        let name = mi.name();
+        /* FIXME (#623): support other literal kinds */
+        let value = mi.value_str().unwrap();
+        rbml_w.start_tag(tag_meta_item_name_value);
+        rbml_w.wr_tagged_str(tag_meta_item_name, &name);
+        rbml_w.wr_tagged_str(tag_meta_item_value, &value);
+        rbml_w.end_tag();
+    } else { // it must be a list
+        let name = mi.name();
+        let items = mi.meta_item_list().unwrap();
         rbml_w.start_tag(tag_meta_item_list);
-        rbml_w.wr_tagged_str(tag_meta_item_name, name);
+        rbml_w.wr_tagged_str(tag_meta_item_name, &name);
         for inner_item in items {
             encode_meta_item(rbml_w, &inner_item);
         }
         rbml_w.end_tag();
-      }
     }
 }
 
@@ -1464,7 +1461,7 @@ fn encode_attributes(rbml_w: &mut Encoder, attrs: &[ast::Attribute]) {
     for attr in attrs {
         rbml_w.start_tag(tag_attribute);
         rbml_w.wr_tagged_u8(tag_attribute_is_sugared_doc, attr.node.is_sugared_doc as u8);
-        encode_meta_item(rbml_w, &attr.node.value);
+        encode_meta_item(rbml_w, attr.meta());
         rbml_w.end_tag();
     }
     rbml_w.end_tag();
diff --git a/src/librustc_metadata/macro_import.rs b/src/librustc_metadata/macro_import.rs
index 7dadf8d108a..4be044c1df3 100644
--- a/src/librustc_metadata/macro_import.rs
+++ b/src/librustc_metadata/macro_import.rs
@@ -60,10 +60,10 @@ impl<'a> ext::base::MacroLoader for MacroLoader<'a> {
                     }
                     if let (Some(sel), Some(names)) = (import.as_mut(), names) {
                         for attr in names {
-                            if let ast::MetaItemKind::Word(ref name) = attr.node {
-                                sel.insert(name.clone(), attr.span);
+                            if attr.is_word() {
+                                sel.insert(attr.name().clone(), attr.span());
                             } else {
-                                span_err!(self.sess, attr.span, E0466, "bad macro import");
+                                span_err!(self.sess, attr.span(), E0466, "bad macro import");
                             }
                         }
                     }
@@ -78,10 +78,10 @@ impl<'a> ext::base::MacroLoader for MacroLoader<'a> {
                     };
 
                     for attr in names {
-                        if let ast::MetaItemKind::Word(ref name) = attr.node {
-                            reexport.insert(name.clone(), attr.span);
+                        if attr.is_word() {
+                            reexport.insert(attr.name().clone(), attr.span());
                         } else {
-                            call_bad_macro_reexport(self.sess, attr.span);
+                            call_bad_macro_reexport(self.sess, attr.span());
                         }
                     }
                 }