Refactor `Attribute` to use `Path` and `TokenStream` instead of `MetaItem`.

16 files changed, 504 insertions, 229 deletions

diff --git a/src/libsyntax/ast.rs b/src/libsyntax/ast.rs
index 981667337d5..5deb91ef53a 100644
--- a/src/libsyntax/ast.rs
+++ b/src/libsyntax/ast.rs
@@ -116,6 +116,12 @@ pub struct Path {
     pub segments: Vec<PathSegment>,
 }
 
+impl<'a> PartialEq<&'a str> for Path {
+    fn eq(&self, string: &&'a str) -> bool {
+        self.segments.len() == 1 && self.segments[0].identifier.name == *string
+    }
+}
+
 impl fmt::Debug for Path {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "path({})", pprust::path_to_string(self))
@@ -1679,7 +1685,8 @@ pub struct AttrId(pub usize);
 pub struct Attribute {
     pub id: AttrId,
     pub style: AttrStyle,
-    pub value: MetaItem,
+    pub path: Path,
+    pub tokens: TokenStream,
     pub is_sugared_doc: bool,
     pub span: Span,
 }
diff --git a/src/libsyntax/attr.rs b/src/libsyntax/attr.rs
index 096657a6e7a..68f1f690a62 100644
--- a/src/libsyntax/attr.rs
+++ b/src/libsyntax/attr.rs
@@ -15,20 +15,24 @@ pub use self::ReprAttr::*;
 pub use self::IntType::*;
 
 use ast;
-use ast::{AttrId, Attribute, Name};
+use ast::{AttrId, Attribute, Name, Ident};
 use ast::{MetaItem, MetaItemKind, NestedMetaItem, NestedMetaItemKind};
-use ast::{Lit, Expr, Item, Local, Stmt, StmtKind};
+use ast::{Lit, LitKind, Expr, Item, Local, Stmt, StmtKind};
 use codemap::{Spanned, spanned, dummy_spanned, mk_sp};
 use syntax_pos::{Span, BytePos, DUMMY_SP};
 use errors::Handler;
 use feature_gate::{Features, GatedCfg};
 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
-use parse::ParseSess;
+use parse::parser::Parser;
+use parse::{self, ParseSess, PResult};
+use parse::token::{self, Token};
 use ptr::P;
 use symbol::Symbol;
+use tokenstream::{TokenStream, TokenTree, Delimited};
 use util::ThinVec;
 
 use std::cell::{RefCell, Cell};
+use std::iter;
 
 thread_local! {
     static USED_ATTRS: RefCell<Vec<u64>> = RefCell::new(Vec::new());
@@ -185,26 +189,38 @@ impl NestedMetaItem {
 
 impl Attribute {
     pub fn check_name(&self, name: &str) -> bool {
-        let matches = self.name() == name;
+        let matches = self.path == name;
         if matches {
             mark_used(self);
         }
         matches
     }
 
-    pub fn name(&self) -> Name { self.meta().name() }
+    pub fn name(&self) -> Option<Name> {
+        match self.path.segments.len() {
+            1 => Some(self.path.segments[0].identifier.name),
+            _ => None,
+        }
+    }
 
     pub fn value_str(&self) -> Option<Symbol> {
-        self.meta().value_str()
+        self.meta().and_then(|meta| meta.value_str())
     }
 
-    pub fn meta_item_list(&self) -> Option<&[NestedMetaItem]> {
-        self.meta().meta_item_list()
+    pub fn meta_item_list(&self) -> Option<Vec<NestedMetaItem>> {
+        match self.meta() {
+            Some(MetaItem { node: MetaItemKind::List(list), .. }) => Some(list),
+            _ => None
+        }
     }
 
-    pub fn is_word(&self) -> bool { self.meta().is_word() }
+    pub fn is_word(&self) -> bool {
+        self.path.segments.len() == 1 && self.tokens.is_empty()
+    }
 
-    pub fn span(&self) -> Span { self.meta().span }
+    pub fn span(&self) -> Span {
+        self.span
+    }
 
     pub fn is_meta_item_list(&self) -> bool {
         self.meta_item_list().is_some()
@@ -225,7 +241,7 @@ impl MetaItem {
         match self.node {
             MetaItemKind::NameValue(ref v) => {
                 match v.node {
-                    ast::LitKind::Str(ref s, _) => Some((*s).clone()),
+                    LitKind::Str(ref s, _) => Some((*s).clone()),
                     _ => None,
                 }
             },
@@ -264,8 +280,35 @@ impl MetaItem {
 
 impl Attribute {
     /// Extract the MetaItem from inside this Attribute.
-    pub fn meta(&self) -> &MetaItem {
-        &self.value
+    pub fn meta(&self) -> Option<MetaItem> {
+        let mut tokens = self.tokens.trees().peekable();
+        Some(MetaItem {
+            name: match self.path.segments.len() {
+                1 => self.path.segments[0].identifier.name,
+                _ => return None,
+            },
+            node: if let Some(node) = MetaItemKind::from_tokens(&mut tokens) {
+                if tokens.peek().is_some() {
+                    return None;
+                }
+                node
+            } else {
+                return None;
+            },
+            span: self.span,
+        })
+    }
+
+    pub fn parse_meta<'a>(&self, sess: &'a ParseSess) -> PResult<'a, MetaItem> {
+        if self.path.segments.len() > 1 {
+            sess.span_diagnostic.span_err(self.path.span, "expected ident, found path");
+        }
+
+        Ok(MetaItem {
+            name: self.path.segments.last().unwrap().identifier.name,
+            node: Parser::new(sess, self.tokens.clone(), None, false).parse_meta_item_kind()?,
+            span: self.span,
+        })
     }
 
     /// Convert self to a normal #[doc="foo"] comment, if it is a
@@ -293,7 +336,7 @@ impl Attribute {
 /* Constructors */
 
 pub fn mk_name_value_item_str(name: Name, value: Symbol) -> MetaItem {
-    let value_lit = dummy_spanned(ast::LitKind::Str(value, ast::StrStyle::Cooked));
+    let value_lit = dummy_spanned(LitKind::Str(value, ast::StrStyle::Cooked));
     mk_spanned_name_value_item(DUMMY_SP, name, value_lit)
 }
 
@@ -348,7 +391,8 @@ pub fn mk_spanned_attr_inner(sp: Span, id: AttrId, item: MetaItem) -> Attribute
     Attribute {
         id: id,
         style: ast::AttrStyle::Inner,
-        value: item,
+        path: ast::Path::from_ident(item.span, ast::Ident::with_empty_ctxt(item.name)),
+        tokens: item.node.tokens(item.span),
         is_sugared_doc: false,
         span: sp,
     }
@@ -365,7 +409,8 @@ pub fn mk_spanned_attr_outer(sp: Span, id: AttrId, item: MetaItem) -> Attribute
     Attribute {
         id: id,
         style: ast::AttrStyle::Outer,
-        value: item,
+        path: ast::Path::from_ident(item.span, ast::Ident::with_empty_ctxt(item.name)),
+        tokens: item.node.tokens(item.span),
         is_sugared_doc: false,
         span: sp,
     }
@@ -374,32 +419,25 @@ pub fn mk_spanned_attr_outer(sp: Span, id: AttrId, item: MetaItem) -> Attribute
 pub fn mk_sugared_doc_attr(id: AttrId, text: Symbol, lo: BytePos, hi: BytePos)
                            -> Attribute {
     let style = doc_comment_style(&text.as_str());
-    let lit = spanned(lo, hi, ast::LitKind::Str(text, ast::StrStyle::Cooked));
+    let lit = spanned(lo, hi, LitKind::Str(text, ast::StrStyle::Cooked));
     Attribute {
         id: id,
         style: style,
-        value: MetaItem {
-            span: mk_sp(lo, hi),
-            name: Symbol::intern("doc"),
-            node: MetaItemKind::NameValue(lit),
-        },
+        path: ast::Path::from_ident(mk_sp(lo, hi), ast::Ident::from_str("doc")),
+        tokens: MetaItemKind::NameValue(lit).tokens(mk_sp(lo, hi)),
         is_sugared_doc: true,
         span: mk_sp(lo, hi),
     }
 }
 
 pub fn list_contains_name(items: &[NestedMetaItem], name: &str) -> bool {
-    debug!("attr::list_contains_name (name={})", name);
     items.iter().any(|item| {
-        debug!("  testing: {:?}", item.name());
         item.check_name(name)
     })
 }
 
 pub fn contains_name(attrs: &[Attribute], name: &str) -> bool {
-    debug!("attr::contains_name (name={})", name);
     attrs.iter().any(|item| {
-        debug!("  testing: {}", item.name());
         item.check_name(name)
     })
 }
@@ -452,8 +490,14 @@ pub enum InlineAttr {
 /// Determine what `#[inline]` attribute is present in `attrs`, if any.
 pub fn find_inline_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> InlineAttr {
     attrs.iter().fold(InlineAttr::None, |ia, attr| {
-        match attr.value.node {
-            _ if attr.value.name != "inline" => ia,
+        if attr.path != "inline" {
+            return ia;
+        }
+        let meta = match attr.meta() {
+            Some(meta) => meta.node,
+            None => return ia,
+        };
+        match meta {
             MetaItemKind::Word => {
                 mark_used(attr);
                 InlineAttr::Hint
@@ -574,14 +618,15 @@ fn find_stability_generic<'a, I>(diagnostic: &Handler,
     let mut rustc_depr: Option<RustcDeprecation> = None;
 
     'outer: for attr in attrs_iter {
-        let tag = attr.name();
-        if tag != "rustc_deprecated" && tag != "unstable" && tag != "stable" {
+        if attr.path != "rustc_deprecated" && attr.path != "unstable" && attr.path != "stable" {
             continue // not a stability level
         }
 
         mark_used(attr);
 
-        if let Some(metas) = attr.meta_item_list() {
+        let meta = attr.meta();
+        if let Some(MetaItem { node: MetaItemKind::List(ref metas), .. }) = meta {
+            let meta = meta.as_ref().unwrap();
             let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
                 if item.is_some() {
                     handle_errors(diagnostic, meta.span, AttrError::MultipleItem(meta.name()));
@@ -596,7 +641,7 @@ fn find_stability_generic<'a, I>(diagnostic: &Handler,
                 }
             };
 
-            match &*tag.as_str() {
+            match &*meta.name.as_str() {
                 "rustc_deprecated" => {
                     if rustc_depr.is_some() {
                         span_err!(diagnostic, item_sp, E0540,
@@ -772,7 +817,7 @@ fn find_deprecation_generic<'a, I>(diagnostic: &Handler,
     let mut depr: Option<Deprecation> = None;
 
     'outer: for attr in attrs_iter {
-        if attr.name() != "deprecated" {
+        if attr.path != "deprecated" {
             continue
         }
 
@@ -847,8 +892,8 @@ pub fn find_deprecation(diagnostic: &Handler, attrs: &[Attribute],
 /// structure layout, and `packed` to remove padding.
 pub fn find_repr_attrs(diagnostic: &Handler, attr: &Attribute) -> Vec<ReprAttr> {
     let mut acc = Vec::new();
-    match attr.value.node {
-        ast::MetaItemKind::List(ref items) if attr.value.name == "repr" => {
+    if attr.path == "repr" {
+        if let Some(items) = attr.meta_item_list() {
             mark_used(attr);
             for item in items {
                 if !item.is_meta_item() {
@@ -883,8 +928,6 @@ pub fn find_repr_attrs(diagnostic: &Handler, attr: &Attribute) -> Vec<ReprAttr>
                 }
             }
         }
-        // Not a "repr" hint: ignore.
-        _ => { }
     }
     acc
 }
@@ -931,6 +974,195 @@ impl IntType {
     }
 }
 
+impl MetaItem {
+    fn tokens(&self) -> TokenStream {
+        let ident = TokenTree::Token(self.span, Token::Ident(Ident::with_empty_ctxt(self.name)));
+        TokenStream::concat(vec![ident.into(), self.node.tokens(self.span)])
+    }
+
+    fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<MetaItem>
+        where I: Iterator<Item = TokenTree>,
+    {
+        let (mut span, name) = match tokens.next() {
+            Some(TokenTree::Token(span, Token::Ident(ident))) => (span, ident.name),
+            _ => return None,
+        };
+        let node = match MetaItemKind::from_tokens(tokens) {
+            Some(node) => node,
+            _ => return None,
+        };
+        if let Some(last_span) = node.last_span() {
+            span.hi = last_span.hi;
+        }
+        Some(MetaItem { name: name, span: span, node: node })
+    }
+}
+
+impl MetaItemKind {
+    fn last_span(&self) -> Option<Span> {
+        match *self {
+            MetaItemKind::Word => None,
+            MetaItemKind::List(ref list) => list.last().map(NestedMetaItem::span),
+            MetaItemKind::NameValue(ref lit) => Some(lit.span),
+        }
+    }
+
+    pub fn tokens(&self, span: Span) -> TokenStream {
+        match *self {
+            MetaItemKind::Word => TokenStream::empty(),
+            MetaItemKind::NameValue(ref lit) => {
+                TokenStream::concat(vec![TokenTree::Token(span, Token::Eq).into(), lit.tokens()])
+            }
+            MetaItemKind::List(ref list) => {
+                let mut tokens = Vec::new();
+                for (i, item) in list.iter().enumerate() {
+                    if i > 0 {
+                        tokens.push(TokenTree::Token(span, Token::Comma).into());
+                    }
+                    tokens.push(item.node.tokens());
+                }
+                TokenTree::Delimited(span, Delimited {
+                    delim: token::Paren,
+                    tts: TokenStream::concat(tokens).into(),
+                }).into()
+            }
+        }
+    }
+
+    fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<MetaItemKind>
+        where I: Iterator<Item = TokenTree>,
+    {
+        let delimited = match tokens.peek().cloned() {
+            Some(TokenTree::Token(_, token::Eq)) => {
+                tokens.next();
+                return if let Some(TokenTree::Token(span, token)) = tokens.next() {
+                    LitKind::from_token(token)
+                        .map(|lit| MetaItemKind::NameValue(Spanned { node: lit, span: span }))
+                } else {
+                    None
+                };
+            }
+            Some(TokenTree::Delimited(_, ref delimited)) if delimited.delim == token::Paren => {
+                tokens.next();
+                delimited.stream()
+            }
+            _ => return Some(MetaItemKind::Word),
+        };
+
+        let mut tokens = delimited.into_trees().peekable();
+        let mut result = Vec::new();
+        while let Some(..) = tokens.peek() {
+            match NestedMetaItemKind::from_tokens(&mut tokens) {
+                Some(item) => result.push(Spanned { span: item.span(), node: item }),
+                None => return None,
+            }
+            match tokens.next() {
+                None | Some(TokenTree::Token(_, Token::Comma)) => {}
+                _ => return None,
+            }
+        }
+        Some(MetaItemKind::List(result))
+    }
+}
+
+impl NestedMetaItemKind {
+    fn span(&self) -> Span {
+        match *self {
+            NestedMetaItemKind::MetaItem(ref item) => item.span,
+            NestedMetaItemKind::Literal(ref lit) => lit.span,
+        }
+    }
+
+    fn tokens(&self) -> TokenStream {
+        match *self {
+            NestedMetaItemKind::MetaItem(ref item) => item.tokens(),
+            NestedMetaItemKind::Literal(ref lit) => lit.tokens(),
+        }
+    }
+
+    fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<NestedMetaItemKind>
+        where I: Iterator<Item = TokenTree>,
+    {
+        if let Some(TokenTree::Token(span, token)) = tokens.peek().cloned() {
+            if let Some(node) = LitKind::from_token(token) {
+                tokens.next();
+                return Some(NestedMetaItemKind::Literal(Spanned { node: node, span: span }));
+            }
+        }
+
+        MetaItem::from_tokens(tokens).map(NestedMetaItemKind::MetaItem)
+    }
+}
+
+impl Lit {
+    fn tokens(&self) -> TokenStream {
+        TokenTree::Token(self.span, self.node.token()).into()
+    }
+}
+
+impl LitKind {
+    fn token(&self) -> Token {
+        use std::ascii;
+
+        match *self {
+            LitKind::Str(string, ast::StrStyle::Cooked) => {
+                let mut escaped = String::new();
+                for ch in string.as_str().chars() {
+                    escaped.extend(ch.escape_unicode());
+                }
+                Token::Literal(token::Lit::Str_(Symbol::intern(&escaped)), None)
+            }
+            LitKind::Str(string, ast::StrStyle::Raw(n)) => {
+                Token::Literal(token::Lit::StrRaw(string, n), None)
+            }
+            LitKind::ByteStr(ref bytes) => {
+                let string = bytes.iter().cloned().flat_map(ascii::escape_default)
+                    .map(Into::<char>::into).collect::<String>();
+                Token::Literal(token::Lit::ByteStr(Symbol::intern(&string)), None)
+            }
+            LitKind::Byte(byte) => {
+                let string: String = ascii::escape_default(byte).map(Into::<char>::into).collect();
+                Token::Literal(token::Lit::Byte(Symbol::intern(&string)), None)
+            }
+            LitKind::Char(ch) => {
+                let string: String = ch.escape_default().map(Into::<char>::into).collect();
+                Token::Literal(token::Lit::Char(Symbol::intern(&string)), None)
+            }
+            LitKind::Int(n, ty) => {
+                let suffix = match ty {
+                    ast::LitIntType::Unsigned(ty) => Some(Symbol::intern(ty.ty_to_string())),
+                    ast::LitIntType::Signed(ty) => Some(Symbol::intern(ty.ty_to_string())),
+                    ast::LitIntType::Unsuffixed => None,
+                };
+                Token::Literal(token::Lit::Integer(Symbol::intern(&n.to_string())), suffix)
+            }
+            LitKind::Float(symbol, ty) => {
+                Token::Literal(token::Lit::Float(symbol), Some(Symbol::intern(ty.ty_to_string())))
+            }
+            LitKind::FloatUnsuffixed(symbol) => Token::Literal(token::Lit::Float(symbol), None),
+            LitKind::Bool(value) => Token::Ident(Ident::with_empty_ctxt(Symbol::intern(match value {
+                true => "true",
+                false => "false",
+            }))),
+        }
+    }
+
+    fn from_token(token: Token) -> Option<LitKind> {
+        match token {
+            Token::Ident(ident) if ident.name == "true" => Some(LitKind::Bool(true)),
+            Token::Ident(ident) if ident.name == "false" => Some(LitKind::Bool(false)),
+            Token::Literal(lit, suf) => {
+                let (suffix_illegal, result) = parse::lit_token(lit, suf, None);
+                if suffix_illegal && suf.is_some() {
+                    return None;
+                }
+                result
+            }
+            _ => None,
+        }
+    }
+}
+
 pub trait HasAttrs: Sized {
     fn attrs(&self) -> &[ast::Attribute];
     fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self;
diff --git a/src/libsyntax/config.rs b/src/libsyntax/config.rs
index ea12a31770f..2591a576669 100644
--- a/src/libsyntax/config.rs
+++ b/src/libsyntax/config.rs
@@ -109,7 +109,8 @@ impl<'a> StripUnconfigured<'a> {
                     self.process_cfg_attr(ast::Attribute {
                         id: attr::mk_attr_id(),
                         style: attr.style,
-                        value: mi.clone(),
+                        path: ast::Path::from_ident(mi.span, ast::Ident::with_empty_ctxt(mi.name)),
+                        tokens: mi.node.tokens(mi.span),
                         is_sugared_doc: false,
                         span: mi.span,
                     })
@@ -132,8 +133,9 @@ impl<'a> StripUnconfigured<'a> {
                 return false;
             }
 
-            let mis = match attr.value.node {
-                ast::MetaItemKind::List(ref mis) if is_cfg(&attr) => mis,
+            let mis = attr.meta_item_list();
+            let mis = match mis {
+                Some(ref mis) if is_cfg(&attr) => mis,
                 _ => return true
             };
 
diff --git a/src/libsyntax/ext/derive.rs b/src/libsyntax/ext/derive.rs
index 77cc7bab031..5b253635f25 100644
--- a/src/libsyntax/ext/derive.rs
+++ b/src/libsyntax/ext/derive.rs
@@ -18,7 +18,7 @@ use syntax_pos::Span;
 pub fn collect_derives(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>) -> Vec<(Symbol, Span)> {
     let mut result = Vec::new();
     attrs.retain(|attr| {
-        if attr.name() != "derive" {
+        if attr.path != "derive" {
             return true;
         }
 
@@ -27,7 +27,7 @@ pub fn collect_derives(cx: &mut ExtCtxt, attrs: &mut Vec<ast::Attribute>) -> Vec
             return false;
         }
 
-        let traits = attr.meta_item_list().unwrap_or(&[]).to_owned();
+        let traits = attr.meta_item_list().unwrap_or_else(Vec::new);
         if traits.is_empty() {
             cx.span_warn(attr.span, "empty trait list in `derive`");
             return false;
diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 10168f010a0..c1095d34456 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -272,7 +272,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     self.collect_invocations(expansion, &[])
                 } else if let InvocationKind::Attr { attr: None, traits, item } = invoc.kind {
                     let item = item
-                        .map_attrs(|mut attrs| { attrs.retain(|a| a.name() != "derive"); attrs });
+                        .map_attrs(|mut attrs| { attrs.retain(|a| a.path != "derive"); attrs });
                     let item_with_markers =
                         add_derived_markers(&mut self.cx, &traits, item.clone());
                     let derives = derives.entry(invoc.expansion_data.mark).or_insert_with(Vec::new);
@@ -380,7 +380,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
         };
 
         attr::mark_used(&attr);
-        let name = attr.name();
+        let name = attr.path.segments[0].identifier.name;
         self.cx.bt_push(ExpnInfo {
             call_site: attr.span,
             callee: NameAndSpan {
@@ -392,25 +392,25 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
 
         match *ext {
             MultiModifier(ref mac) => {
-                let item = mac.expand(self.cx, attr.span, &attr.value, item);
+                let meta = panictry!(attr.parse_meta(&self.cx.parse_sess));
+                let item = mac.expand(self.cx, attr.span, &meta, item);
                 kind.expect_from_annotatables(item)
             }
             MultiDecorator(ref mac) => {
                 let mut items = Vec::new();
-                mac.expand(self.cx, attr.span, &attr.value, &item,
-                           &mut |item| items.push(item));
+                let meta = panictry!(attr.parse_meta(&self.cx.parse_sess));
+                mac.expand(self.cx, attr.span, &meta, &item, &mut |item| items.push(item));
                 items.push(item);
                 kind.expect_from_annotatables(items)
             }
             SyntaxExtension::AttrProcMacro(ref mac) => {
-                let attr_toks = stream_for_attr_args(&attr, &self.cx.parse_sess);
                 let item_toks = stream_for_item(&item, &self.cx.parse_sess);
 
                 let span = Span {
                     expn_id: self.cx.codemap().record_expansion(ExpnInfo {
                         call_site: attr.span,
                         callee: NameAndSpan {
-                            format: MacroAttribute(name),
+                            format: MacroAttribute(Symbol::intern(&format!("{}", attr.path))),
                             span: None,
                             allow_internal_unstable: false,
                         },
@@ -418,7 +418,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     ..attr.span
                 };
 
-                let tok_result = mac.expand(self.cx, attr.span, attr_toks, item_toks);
+                let tok_result = mac.expand(self.cx, attr.span, attr.tokens.clone(), item_toks);
                 self.parse_expansion(tok_result, kind, name, span)
             }
             SyntaxExtension::ProcMacroDerive(..) | SyntaxExtension::BuiltinDerive(..) => {
@@ -784,32 +784,6 @@ fn stream_for_item(item: &Annotatable, parse_sess: &ParseSess) -> TokenStream {
     string_to_stream(text, parse_sess)
 }
 
-fn stream_for_attr_args(attr: &ast::Attribute, parse_sess: &ParseSess) -> TokenStream {
-    use ast::MetaItemKind::*;
-    use print::pp::Breaks;
-    use print::pprust::PrintState;
-
-    let token_string = match attr.value.node {
-        // For `#[foo]`, an empty token
-        Word => return TokenStream::empty(),
-        // For `#[foo(bar, baz)]`, returns `(bar, baz)`
-        List(ref items) => pprust::to_string(|s| {
-            s.popen()?;
-            s.commasep(Breaks::Consistent,
-                       &items[..],
-                       |s, i| s.print_meta_list_item(&i))?;
-            s.pclose()
-        }),
-        // For `#[foo = "bar"]`, returns `= "bar"`
-        NameValue(ref lit) => pprust::to_string(|s| {
-            s.word_space("=")?;
-            s.print_literal(lit)
-        }),
-    };
-
-    string_to_stream(token_string, parse_sess)
-}
-
 fn string_to_stream(text: String, parse_sess: &ParseSess) -> TokenStream {
     let filename = String::from("<macro expansion>");
     filemap_to_stream(parse_sess, parse_sess.codemap().new_filemap(filename, None, text))
diff --git a/src/libsyntax/ext/quote.rs b/src/libsyntax/ext/quote.rs
index 69ff726e719..10b7249743b 100644
--- a/src/libsyntax/ext/quote.rs
+++ b/src/libsyntax/ext/quote.rs
@@ -220,16 +220,24 @@ pub mod rt {
     }
 
     impl ToTokens for ast::Attribute {
-        fn to_tokens(&self, cx: &ExtCtxt) -> Vec<TokenTree> {
+        fn to_tokens(&self, _cx: &ExtCtxt) -> Vec<TokenTree> {
             let mut r = vec![];
             // FIXME: The spans could be better
             r.push(TokenTree::Token(self.span, token::Pound));
             if self.style == ast::AttrStyle::Inner {
                 r.push(TokenTree::Token(self.span, token::Not));
             }
+            let mut inner = Vec::new();
+            for (i, segment) in self.path.segments.iter().enumerate() {
+                if i > 0 {
+                    inner.push(TokenTree::Token(self.span, token::Colon).into());
+                }
+                inner.push(TokenTree::Token(self.span, token::Ident(segment.identifier)).into());
+            }
+            inner.push(self.tokens.clone());
+
             r.push(TokenTree::Delimited(self.span, tokenstream::Delimited {
-                delim: token::Bracket,
-                tts: self.value.to_tokens(cx).into_iter().collect::<TokenStream>().into(),
+                delim: token::Bracket, tts: TokenStream::concat(inner).into()
             }));
             r
         }
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index e7bf16eae9e..2c3ad98a6be 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -859,35 +859,34 @@ macro_rules! gate_feature {
 impl<'a> Context<'a> {
     fn check_attribute(&self, attr: &ast::Attribute, is_macro: bool) {
         debug!("check_attribute(attr = {:?})", attr);
-        let name = &*attr.name().as_str();
+        let name = unwrap_or!(attr.name(), return);
+
         for &(n, ty, ref gateage) in BUILTIN_ATTRIBUTES {
-            if n == name {
+            if name == n {
                 if let &Gated(_, ref name, ref desc, ref has_feature) = gateage {
                     gate_feature_fn!(self, has_feature, attr.span, name, desc);
                 }
-                debug!("check_attribute: {:?} is builtin, {:?}, {:?}", name, ty, gateage);
+                debug!("check_attribute: {:?} is builtin, {:?}, {:?}", attr.path, ty, gateage);
                 return;
             }
         }
         for &(ref n, ref ty) in self.plugin_attributes {
-            if n == name {
+            if attr.path == &**n {
                 // Plugins can't gate attributes, so we don't check for it
                 // unlike the code above; we only use this loop to
                 // short-circuit to avoid the checks below
-                debug!("check_attribute: {:?} is registered by a plugin, {:?}", name, ty);
+                debug!("check_attribute: {:?} is registered by a plugin, {:?}", attr.path, ty);
                 return;
             }
         }
-        if name.starts_with("rustc_") {
+        if name.as_str().starts_with("rustc_") {
             gate_feature!(self, rustc_attrs, attr.span,
                           "unless otherwise specified, attributes \
                            with the prefix `rustc_` \
                            are reserved for internal compiler diagnostics");
-        } else if name.starts_with("derive_") {
+        } else if name.as_str().starts_with("derive_") {
             gate_feature!(self, custom_derive, attr.span, EXPLAIN_DERIVE_UNDERSCORE);
-        } else if attr::is_known(attr) {
-            debug!("check_attribute: {:?} is known", name);
-        } else {
+        } else if !attr::is_known(attr) {
             // Only run the custom attribute lint during regular
             // feature gate checking. Macro gating runs
             // before the plugin attributes are registered
@@ -898,7 +897,7 @@ impl<'a> Context<'a> {
                                         unknown to the compiler and \
                                         may have meaning \
                                         added to it in the future",
-                                       name));
+                                       attr.path));
             }
         }
     }
@@ -1097,7 +1096,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             self.context.check_attribute(attr, false);
         }
 
-        if contains_novel_literal(&attr.value) {
+        let meta = panictry!(attr.parse_meta(&self.context.parse_sess));
+        if contains_novel_literal(&meta) {
             gate_feature_post!(&self, attr_literals, attr.span,
                                "non-string literals in attributes, or string \
                                literals in top-level positions, are experimental");
@@ -1160,8 +1160,8 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
                                                                        `#[repr(simd)]` instead");
                 }
                 for attr in &i.attrs {
-                    if attr.name() == "repr" {
-                        for item in attr.meta_item_list().unwrap_or(&[]) {
+                    if attr.path == "repr" {
+                        for item in attr.meta_item_list().unwrap_or_else(Vec::new) {
                             if item.check_name("simd") {
                                 gate_feature_post!(&self, repr_simd, i.span,
                                                    "SIMD types are experimental \
diff --git a/src/libsyntax/fold.rs b/src/libsyntax/fold.rs
index fb4eb19be2b..903dac1f379 100644
--- a/src/libsyntax/fold.rs
+++ b/src/libsyntax/fold.rs
@@ -488,7 +488,8 @@ pub fn noop_fold_attribute<T: Folder>(attr: Attribute, fld: &mut T) -> Option<At
     Some(Attribute {
         id: attr.id,
         style: attr.style,
-        value: fld.fold_meta_item(attr.value),
+        path: fld.fold_path(attr.path),
+        tokens: fld.fold_tts(attr.tokens),
         is_sugared_doc: attr.is_sugared_doc,
         span: fld.new_span(attr.span),
     })
@@ -611,7 +612,7 @@ pub fn noop_fold_interpolated<T: Folder>(nt: token::Nonterminal, fld: &mut T)
         token::NtExpr(expr) => token::NtExpr(fld.fold_expr(expr)),
         token::NtTy(ty) => token::NtTy(fld.fold_ty(ty)),
         token::NtIdent(id) => token::NtIdent(Spanned::<Ident>{node: fld.fold_ident(id.node), ..id}),
-        token::NtMeta(meta_item) => token::NtMeta(fld.fold_meta_item(meta_item)),
+        token::NtMeta(meta) => token::NtMeta(fld.fold_meta_item(meta)),
         token::NtPath(path) => token::NtPath(fld.fold_path(path)),
         token::NtTT(tt) => token::NtTT(fld.fold_tt(tt)),
         token::NtArm(arm) => token::NtArm(fld.fold_arm(arm)),
@@ -1369,7 +1370,7 @@ mod tests {
             matches_codepattern,
             "matches_codepattern",
             pprust::to_string(|s| fake_print_crate(s, &folded_crate)),
-            "#[a]mod zz{fn zz(zz:zz,zz:zz){zz!(zz,zz,zz);zz;zz}}".to_string());
+            "#[zz]mod zz{fn zz(zz:zz,zz:zz){zz!(zz,zz,zz);zz;zz}}".to_string());
     }
 
     // even inside macro defs....
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 39a9aff48bf..4c9a5d512af 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -65,6 +65,16 @@ macro_rules! panictry {
     })
 }
 
+#[macro_export]
+macro_rules! unwrap_or {
+    ($opt:expr, $default:expr) => {
+        match $opt {
+            Some(x) => x,
+            None => $default,
+        }
+    }
+}
+
 #[macro_use]
 pub mod diagnostics {
     #[macro_use]
diff --git a/src/libsyntax/parse/attr.rs b/src/libsyntax/parse/attr.rs
index ded676da3c6..272cff7ad34 100644
--- a/src/libsyntax/parse/attr.rs
+++ b/src/libsyntax/parse/attr.rs
@@ -143,7 +143,8 @@ impl<'a> Parser<'a> {
         Ok(ast::Attribute {
             id: attr::mk_attr_id(),
             style: style,
-            value: value,
+            path: ast::Path::from_ident(value.span, ast::Ident::with_empty_ctxt(value.name)),
+            tokens: value.node.tokens(value.span),
             is_sugared_doc: false,
             span: span,
         })
@@ -221,15 +222,20 @@ impl<'a> Parser<'a> {
 
         let lo = self.span.lo;
         let ident = self.parse_ident()?;
-        let node = if self.eat(&token::Eq) {
+        let node = self.parse_meta_item_kind()?;
+        let hi = self.prev_span.hi;
+        Ok(ast::MetaItem { name: ident.name, node: node, span: mk_sp(lo, hi) })
+    }
+
+    pub fn parse_meta_item_kind(&mut self) -> PResult<'a, ast::MetaItemKind> {
+        Ok(if self.eat(&token::Eq) {
             ast::MetaItemKind::NameValue(self.parse_unsuffixed_lit()?)
         } else if self.token == token::OpenDelim(token::Paren) {
             ast::MetaItemKind::List(self.parse_meta_seq()?)
         } else {
+            self.eat(&token::OpenDelim(token::Paren));
             ast::MetaItemKind::Word
-        };
-        let hi = self.prev_span.hi;
-        Ok(ast::MetaItem { name: ident.name, node: node, span: mk_sp(lo, hi) })
+        })
     }
 
     /// matches meta_item_inner : (meta_item | UNSUFFIXED_LIT) ;
diff --git a/src/libsyntax/parse/mod.rs b/src/libsyntax/parse/mod.rs
index c00d2952b3b..2bdd3938d6b 100644
--- a/src/libsyntax/parse/mod.rs
+++ b/src/libsyntax/parse/mod.rs
@@ -374,38 +374,80 @@ fn looks_like_width_suffix(first_chars: &[char], s: &str) -> bool {
         s[1..].chars().all(|c| '0' <= c && c <= '9')
 }
 
-fn filtered_float_lit(data: Symbol, suffix: Option<Symbol>, sd: &Handler, sp: Span)
-                      -> ast::LitKind {
+macro_rules! err {
+    ($opt_diag:expr, |$span:ident, $diag:ident| $($body:tt)*) => {
+        match $opt_diag {
+            Some(($span, $diag)) => { $($body)* }
+            None => return None,
+        }
+    }
+}
+
+pub fn lit_token(lit: token::Lit, suf: Option<Symbol>, diag: Option<(Span, &Handler)>)
+                 -> (bool /* suffix illegal? */, Option<ast::LitKind>) {
+    use ast::LitKind;
+
+    match lit {
+       token::Byte(i) => (true, Some(LitKind::Byte(byte_lit(&i.as_str()).0))),
+       token::Char(i) => (true, Some(LitKind::Char(char_lit(&i.as_str()).0))),
+
+        // There are some valid suffixes for integer and float literals,
+        // so all the handling is done internally.
+        token::Integer(s) => (false, integer_lit(&s.as_str(), suf, diag)),
+        token::Float(s) => (false, float_lit(&s.as_str(), suf, diag)),
+
+        token::Str_(s) => {
+            let s = Symbol::intern(&str_lit(&s.as_str()));
+            (true, Some(LitKind::Str(s, ast::StrStyle::Cooked)))
+        }
+        token::StrRaw(s, n) => {
+            let s = Symbol::intern(&raw_str_lit(&s.as_str()));
+            (true, Some(LitKind::Str(s, ast::StrStyle::Raw(n))))
+        }
+        token::ByteStr(i) => {
+            (true, Some(LitKind::ByteStr(byte_str_lit(&i.as_str()))))
+        }
+        token::ByteStrRaw(i, _) => {
+            (true, Some(LitKind::ByteStr(Rc::new(i.to_string().into_bytes()))))
+        }
+    }
+}
+
+fn filtered_float_lit(data: Symbol, suffix: Option<Symbol>, diag: Option<(Span, &Handler)>)
+                      -> Option<ast::LitKind> {
     debug!("filtered_float_lit: {}, {:?}", data, suffix);
     let suffix = match suffix {
         Some(suffix) => suffix,
-        None => return ast::LitKind::FloatUnsuffixed(data),
+        None => return Some(ast::LitKind::FloatUnsuffixed(data)),
     };
 
-    match &*suffix.as_str() {
+    Some(match &*suffix.as_str() {
         "f32" => ast::LitKind::Float(data, ast::FloatTy::F32),
         "f64" => ast::LitKind::Float(data, ast::FloatTy::F64),
         suf => {
-            if suf.len() >= 2 && looks_like_width_suffix(&['f'], suf) {
-                // if it looks like a width, lets try to be helpful.
-                sd.struct_span_err(sp, &format!("invalid width `{}` for float literal", &suf[1..]))
-                 .help("valid widths are 32 and 64")
-                 .emit();
-            } else {
-                sd.struct_span_err(sp, &format!("invalid suffix `{}` for float literal", suf))
-                  .help("valid suffixes are `f32` and `f64`")
-                  .emit();
-            }
+            err!(diag, |span, diag| {
+                if suf.len() >= 2 && looks_like_width_suffix(&['f'], suf) {
+                    // if it looks like a width, lets try to be helpful.
+                    let msg = format!("invalid width `{}` for float literal", &suf[1..]);
+                    diag.struct_span_err(span, &msg).help("valid widths are 32 and 64").emit()
+                } else {
+                    let msg = format!("invalid suffix `{}` for float literal", suf);
+                    diag.struct_span_err(span, &msg)
+                        .help("valid suffixes are `f32` and `f64`")
+                        .emit();
+                }
+            });
 
             ast::LitKind::FloatUnsuffixed(data)
         }
-    }
+    })
 }
-pub fn float_lit(s: &str, suffix: Option<Symbol>, sd: &Handler, sp: Span) -> ast::LitKind {
+pub fn float_lit(s: &str, suffix: Option<Symbol>, diag: Option<(Span, &Handler)>)
+                 -> Option<ast::LitKind> {
     debug!("float_lit: {:?}, {:?}", s, suffix);
     // FIXME #2252: bounds checking float literals is deferred until trans
     let s = s.chars().filter(|&c| c != '_').collect::<String>();
-    filtered_float_lit(Symbol::intern(&s), suffix, sd, sp)
+    filtered_float_lit(Symbol::intern(&s), suffix, diag)
 }
 
 /// Parse a string representing a byte literal into its final form. Similar to `char_lit`
@@ -500,7 +542,8 @@ pub fn byte_str_lit(lit: &str) -> Rc<Vec<u8>> {
     Rc::new(res)
 }
 
-pub fn integer_lit(s: &str, suffix: Option<Symbol>, sd: &Handler, sp: Span) -> ast::LitKind {
+pub fn integer_lit(s: &str, suffix: Option<Symbol>, diag: Option<(Span, &Handler)>)
+                   -> Option<ast::LitKind> {
     // s can only be ascii, byte indexing is fine
 
     let s2 = s.chars().filter(|&c| c != '_').collect::<String>();
@@ -524,13 +567,16 @@ pub fn integer_lit(s: &str, suffix: Option<Symbol>, sd: &Handler, sp: Span) -> a
     // 1f64 and 2f32 etc. are valid float literals.
     if let Some(suf) = suffix {
         if looks_like_width_suffix(&['f'], &suf.as_str()) {
-            match base {
-                16 => sd.span_err(sp, "hexadecimal float literal is not supported"),
-                8 => sd.span_err(sp, "octal float literal is not supported"),
-                2 => sd.span_err(sp, "binary float literal is not supported"),
-                _ => ()
+            let err = match base {
+                16 => Some("hexadecimal float literal is not supported"),
+                8 => Some("octal float literal is not supported"),
+                2 => Some("binary float literal is not supported"),
+                _ => None,
+            };
+            if let Some(err) = err {
+                err!(diag, |span, diag| diag.span_err(span, err));
             }
-            return filtered_float_lit(Symbol::intern(&s), Some(suf), sd, sp)
+            return filtered_float_lit(Symbol::intern(&s), Some(suf), diag)
         }
     }
 
@@ -539,7 +585,9 @@ pub fn integer_lit(s: &str, suffix: Option<Symbol>, sd: &Handler, sp: Span) -> a
     }
 
     if let Some(suf) = suffix {
-        if suf.as_str().is_empty() { sd.span_bug(sp, "found empty literal suffix in Some")}
+        if suf.as_str().is_empty() {
+            err!(diag, |span, diag| diag.span_bug(span, "found empty literal suffix in Some"));
+        }
         ty = match &*suf.as_str() {
             "isize" => ast::LitIntType::Signed(ast::IntTy::Is),
             "i8"  => ast::LitIntType::Signed(ast::IntTy::I8),
@@ -556,17 +604,20 @@ pub fn integer_lit(s: &str, suffix: Option<Symbol>, sd: &Handler, sp: Span) -> a
             suf => {
                 // i<digits> and u<digits> look like widths, so lets
                 // give an error message along those lines
-                if looks_like_width_suffix(&['i', 'u'], suf) {
-                    sd.struct_span_err(sp, &format!("invalid width `{}` for integer literal",
-                                             &suf[1..]))
-                      .help("valid widths are 8, 16, 32, 64 and 128")
-                      .emit();
-                } else {
-                    sd.struct_span_err(sp, &format!("invalid suffix `{}` for numeric literal", suf))
-                      .help("the suffix must be one of the integral types \
-                             (`u32`, `isize`, etc)")
-                      .emit();
-                }
+                err!(diag, |span, diag| {
+                    if looks_like_width_suffix(&['i', 'u'], suf) {
+                        let msg = format!("invalid width `{}` for integer literal", &suf[1..]);
+                        diag.struct_span_err(span, &msg)
+                            .help("valid widths are 8, 16, 32, 64 and 128")
+                            .emit();
+                    } else {
+                        let msg = format!("invalid suffix `{}` for numeric literal", suf);
+                        diag.struct_span_err(span, &msg)
+                            .help("the suffix must be one of the integral types \
+                                   (`u32`, `isize`, etc)")
+                            .emit();
+                    }
+                });
 
                 ty
             }
@@ -576,7 +627,7 @@ pub fn integer_lit(s: &str, suffix: Option<Symbol>, sd: &Handler, sp: Span) -> a
     debug!("integer_lit: the type is {:?}, base {:?}, the new string is {:?}, the original \
            string was {:?}, the original suffix was {:?}", ty, base, s, orig, suffix);
 
-    match u128::from_str_radix(s, base) {
+    Some(match u128::from_str_radix(s, base) {
         Ok(r) => ast::LitKind::Int(r, ty),
         Err(_) => {
             // small bases are lexed as if they were base 10, e.g, the string
@@ -588,11 +639,11 @@ pub fn integer_lit(s: &str, suffix: Option<Symbol>, sd: &Handler, sp: Span) -> a
                 s.chars().any(|c| c.to_digit(10).map_or(false, |d| d >= base));
 
             if !already_errored {
-                sd.span_err(sp, "int literal is too large");
+                err!(diag, |span, diag| diag.span_err(span, "int literal is too large"));
             }
             ast::LitKind::Int(0, ty)
         }
-    }
+    })
 }
 
 #[cfg(test)]
@@ -957,7 +1008,7 @@ mod tests {
         let source = "/// doc comment\r\n/// line 2\r\nfn foo() {}".to_string();
         let item = parse_item_from_source_str(name.clone(), source, &sess)
             .unwrap().unwrap();
-        let docs = item.attrs.iter().filter(|a| a.name() == "doc")
+        let docs = item.attrs.iter().filter(|a| a.path == "doc")
                     .map(|a| a.value_str().unwrap().to_string()).collect::<Vec<_>>();
         let b: &[_] = &["/// doc comment".to_string(), "/// line 2".to_string()];
         assert_eq!(&docs[..], b);
diff --git a/src/libsyntax/parse/parser.rs b/src/libsyntax/parse/parser.rs
index 9872afd27b7..ed512b89987 100644
--- a/src/libsyntax/parse/parser.rs
+++ b/src/libsyntax/parse/parser.rs
@@ -60,7 +60,6 @@ use util::ThinVec;
 use std::collections::HashSet;
 use std::{cmp, mem, slice};
 use std::path::{Path, PathBuf};
-use std::rc::Rc;
 
 bitflags! {
     flags Restrictions: u8 {
@@ -1643,44 +1642,15 @@ impl<'a> Parser<'a> {
                 _ => { return self.unexpected_last(&self.token); }
             },
             token::Literal(lit, suf) => {
-                let (suffix_illegal, out) = match lit {
-                    token::Byte(i) => (true, LitKind::Byte(parse::byte_lit(&i.as_str()).0)),
-                    token::Char(i) => (true, LitKind::Char(parse::char_lit(&i.as_str()).0)),
-
-                    // there are some valid suffixes for integer and
-                    // float literals, so all the handling is done
-                    // internally.
-                    token::Integer(s) => {
-                        let diag = &self.sess.span_diagnostic;
-                        (false, parse::integer_lit(&s.as_str(), suf, diag, self.span))
-                    }
-                    token::Float(s) => {
-                        let diag = &self.sess.span_diagnostic;
-                        (false, parse::float_lit(&s.as_str(), suf, diag, self.span))
-                    }
-
-                    token::Str_(s) => {
-                        let s = Symbol::intern(&parse::str_lit(&s.as_str()));
-                        (true, LitKind::Str(s, ast::StrStyle::Cooked))
-                    }
-                    token::StrRaw(s, n) => {
-                        let s = Symbol::intern(&parse::raw_str_lit(&s.as_str()));
-                        (true, LitKind::Str(s, ast::StrStyle::Raw(n)))
-                    }
-                    token::ByteStr(i) => {
-                        (true, LitKind::ByteStr(parse::byte_str_lit(&i.as_str())))
-                    }
-                    token::ByteStrRaw(i, _) => {
-                        (true, LitKind::ByteStr(Rc::new(i.to_string().into_bytes())))
-                    }
-                };
+                let diag = Some((self.span, &self.sess.span_diagnostic));
+                let (suffix_illegal, result) = parse::lit_token(lit, suf, diag);
 
                 if suffix_illegal {
                     let sp = self.span;
                     self.expect_no_suffix(sp, &format!("{} literal", lit.short_name()), suf)
                 }
 
-                out
+                result.unwrap()
             }
             _ => { return self.unexpected_last(&self.token); }
         };
@@ -5135,11 +5105,9 @@ impl<'a> Parser<'a> {
                     let attr = ast::Attribute {
                         id: attr::mk_attr_id(),
                         style: ast::AttrStyle::Outer,
-                        value: ast::MetaItem {
-                            name: Symbol::intern("warn_directory_ownership"),
-                            node: ast::MetaItemKind::Word,
-                            span: syntax_pos::DUMMY_SP,
-                        },
+                        path: ast::Path::from_ident(syntax_pos::DUMMY_SP,
+                                                    Ident::from_str("warn_directory_ownership")),
+                        tokens: TokenStream::empty(),
                         is_sugared_doc: false,
                         span: syntax_pos::DUMMY_SP,
                     };
diff --git a/src/libsyntax/parse/token.rs b/src/libsyntax/parse/token.rs
index 5b65aac92b8..38377004572 100644
--- a/src/libsyntax/parse/token.rs
+++ b/src/libsyntax/parse/token.rs
@@ -17,7 +17,7 @@ pub use self::Token::*;
 use ast::{self};
 use ptr::P;
 use symbol::keywords;
-use tokenstream;
+use tokenstream::TokenTree;
 
 use std::fmt;
 use std::rc::Rc;
@@ -348,7 +348,7 @@ pub enum Nonterminal {
     /// Stuff inside brackets for attributes
     NtMeta(ast::MetaItem),
     NtPath(ast::Path),
-    NtTT(tokenstream::TokenTree),
+    NtTT(TokenTree),
     // These are not exposed to macros, but are used by quasiquote.
     NtArm(ast::Arm),
     NtImplItem(ast::ImplItem),
diff --git a/src/libsyntax/print/pprust.rs b/src/libsyntax/print/pprust.rs
index 3efadbd00d1..d8af95d8d30 100644
--- a/src/libsyntax/print/pprust.rs
+++ b/src/libsyntax/print/pprust.rs
@@ -28,7 +28,7 @@ use ptr::P;
 use std_inject;
 use symbol::{Symbol, keywords};
 use syntax_pos::DUMMY_SP;
-use tokenstream::{self, TokenTree};
+use tokenstream::{self, TokenStream, TokenTree};
 
 use std::ascii;
 use std::io::{self, Write, Read};
@@ -329,6 +329,10 @@ pub fn tts_to_string(tts: &[tokenstream::TokenTree]) -> String {
     to_string(|s| s.print_tts(tts.iter().cloned().collect()))
 }
 
+pub fn tokens_to_string(tokens: TokenStream) -> String {
+    to_string(|s| s.print_tts(tokens))
+}
+
 pub fn stmt_to_string(stmt: &ast::Stmt) -> String {
     to_string(|s| s.print_stmt(stmt))
 }
@@ -750,7 +754,21 @@ pub trait PrintState<'a> {
                 ast::AttrStyle::Inner => word(self.writer(), "#![")?,
                 ast::AttrStyle::Outer => word(self.writer(), "#[")?,
             }
-            self.print_meta_item(&attr.meta())?;
+            if let Some(mi) = attr.meta() {
+                self.print_meta_item(&mi)?
+            } else {
+                for (i, segment) in attr.path.segments.iter().enumerate() {
+                    if i > 0 {
+                        word(self.writer(), "::")?
+                    }
+                    if segment.identifier.name != keywords::CrateRoot.name() &&
+                       segment.identifier.name != "$crate" {
+                        word(self.writer(), &segment.identifier.name.as_str())?;
+                    }
+                }
+                space(self.writer())?;
+                self.print_tts(attr.tokens.clone())?;
+            }
             word(self.writer(), "]")
         }
     }
@@ -789,6 +807,45 @@ pub trait PrintState<'a> {
         self.end()
     }
 
+    /// This doesn't deserve to be called "pretty" printing, but it should be
+    /// meaning-preserving. A quick hack that might help would be to look at the
+    /// spans embedded in the TTs to decide where to put spaces and newlines.
+    /// But it'd be better to parse these according to the grammar of the
+    /// appropriate macro, transcribe back into the grammar we just parsed from,
+    /// and then pretty-print the resulting AST nodes (so, e.g., we print
+    /// expression arguments as expressions). It can be done! I think.
+    fn print_tt(&mut self, tt: tokenstream::TokenTree) -> io::Result<()> {
+        match tt {
+            TokenTree::Token(_, ref tk) => {
+                word(self.writer(), &token_to_string(tk))?;
+                match *tk {
+                    parse::token::DocComment(..) => {
+                        hardbreak(self.writer())
+                    }
+                    _ => Ok(())
+                }
+            }
+            TokenTree::Delimited(_, ref delimed) => {
+                word(self.writer(), &token_to_string(&delimed.open_token()))?;
+                space(self.writer())?;
+                self.print_tts(delimed.stream())?;
+                space(self.writer())?;
+                word(self.writer(), &token_to_string(&delimed.close_token()))
+            },
+        }
+    }
+
+    fn print_tts(&mut self, tts: tokenstream::TokenStream) -> io::Result<()> {
+        self.ibox(0)?;
+        for (i, tt) in tts.into_trees().enumerate() {
+            if i != 0 {
+                space(self.writer())?;
+            }
+            self.print_tt(tt)?;
+        }
+        self.end()
+    }
+
     fn space_if_not_bol(&mut self) -> io::Result<()> {
         if !self.is_bol() { space(self.writer())?; }
         Ok(())
@@ -1458,45 +1515,6 @@ impl<'a> State<'a> {
         }
     }
 
-    /// This doesn't deserve to be called "pretty" printing, but it should be
-    /// meaning-preserving. A quick hack that might help would be to look at the
-    /// spans embedded in the TTs to decide where to put spaces and newlines.
-    /// But it'd be better to parse these according to the grammar of the
-    /// appropriate macro, transcribe back into the grammar we just parsed from,
-    /// and then pretty-print the resulting AST nodes (so, e.g., we print
-    /// expression arguments as expressions). It can be done! I think.
-    pub fn print_tt(&mut self, tt: tokenstream::TokenTree) -> io::Result<()> {
-        match tt {
-            TokenTree::Token(_, ref tk) => {
-                word(&mut self.s, &token_to_string(tk))?;
-                match *tk {
-                    parse::token::DocComment(..) => {
-                        hardbreak(&mut self.s)
-                    }
-                    _ => Ok(())
-                }
-            }
-            TokenTree::Delimited(_, ref delimed) => {
-                word(&mut self.s, &token_to_string(&delimed.open_token()))?;
-                space(&mut self.s)?;
-                self.print_tts(delimed.stream())?;
-                space(&mut self.s)?;
-                word(&mut self.s, &token_to_string(&delimed.close_token()))
-            },
-        }
-    }
-
-    pub fn print_tts(&mut self, tts: tokenstream::TokenStream) -> io::Result<()> {
-        self.ibox(0)?;
-        for (i, tt) in tts.into_trees().enumerate() {
-            if i != 0 {
-                space(&mut self.s)?;
-            }
-            self.print_tt(tt)?;
-        }
-        self.end()
-    }
-
     pub fn print_variant(&mut self, v: &ast::Variant) -> io::Result<()> {
         self.head("")?;
         let generics = ast::Generics::default();
diff --git a/src/libsyntax/std_inject.rs b/src/libsyntax/std_inject.rs
index 4a2dfaf6124..94954e2c429 100644
--- a/src/libsyntax/std_inject.rs
+++ b/src/libsyntax/std_inject.rs
@@ -15,6 +15,7 @@ use syntax_pos::{DUMMY_SP, Span};
 use codemap::{self, ExpnInfo, NameAndSpan, MacroAttribute};
 use parse::ParseSess;
 use ptr::P;
+use tokenstream::TokenStream;
 
 /// Craft a span that will be ignored by the stability lint's
 /// call to codemap's is_internal check.
@@ -70,11 +71,8 @@ pub fn maybe_inject_crates_ref(sess: &ParseSess,
     krate.module.items.insert(0, P(ast::Item {
         attrs: vec![ast::Attribute {
             style: ast::AttrStyle::Outer,
-            value: ast::MetaItem {
-                name: Symbol::intern("prelude_import"),
-                node: ast::MetaItemKind::Word,
-                span: span,
-            },
+            path: ast::Path::from_ident(span, ast::Ident::from_str("prelude_import")),
+            tokens: TokenStream::empty(),
             id: attr::mk_attr_id(),
             is_sugared_doc: false,
             span: span,
diff --git a/src/libsyntax/tokenstream.rs b/src/libsyntax/tokenstream.rs
index 2da442a1a53..35e4d9eb68a 100644
--- a/src/libsyntax/tokenstream.rs
+++ b/src/libsyntax/tokenstream.rs
@@ -360,7 +360,7 @@ impl PartialEq<ThinTokenStream> for ThinTokenStream {
 
 impl fmt::Display for TokenStream {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.write_str(&pprust::tts_to_string(&self.trees().collect::<Vec<_>>()))
+        f.write_str(&pprust::tokens_to_string(self.clone()))
     }
 }