src/libsyntax/attr.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // Functions dealing with attributes and meta items
  12
  13 pub use self::StabilityLevel::*;
  14 pub use self::ReprAttr::*;
  15 pub use self::IntType::*;
  16
  17 use ast;
  18 use ast::{AttrId, Attribute, Name, Ident};
  19 use ast::{MetaItem, MetaItemKind, NestedMetaItem, NestedMetaItemKind};
  20 use ast::{Lit, LitKind, Expr, ExprKind, Item, Local, Stmt, StmtKind};
  21 use codemap::{Spanned, respan, dummy_spanned};
  22 use syntax_pos::{Span, DUMMY_SP};
  23 use errors::Handler;
  24 use feature_gate::{Features, GatedCfg};
  25 use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
  26 use parse::parser::Parser;
  27 use parse::{self, ParseSess, PResult};
  28 use parse::token::{self, Token};
  29 use ptr::P;
  30 use symbol::Symbol;
  31 use tokenstream::{TokenStream, TokenTree, Delimited};
  32 use util::ThinVec;
  33
  34 use std::cell::{RefCell, Cell};
  35 use std::iter;
  36
  37 thread_local! {
  38     static USED_ATTRS: RefCell<Vec<u64>> = RefCell::new(Vec::new());
  39     static KNOWN_ATTRS: RefCell<Vec<u64>> = RefCell::new(Vec::new());
  40 }
  41
  42 enum AttrError {
  43     MultipleItem(Name),
  44     UnknownMetaItem(Name),
  45     MissingSince,
  46     MissingFeature,
  47     MultipleStabilityLevels,
  48     UnsupportedLiteral
  49 }
  50
  51 fn handle_errors(diag: &Handler, span: Span, error: AttrError) {
  52     match error {
  53         AttrError::MultipleItem(item) => span_err!(diag, span, E0538,
  54                                                    "multiple '{}' items", item),
  55         AttrError::UnknownMetaItem(item) => span_err!(diag, span, E0541,
  56                                                       "unknown meta item '{}'", item),
  57         AttrError::MissingSince => span_err!(diag, span, E0542, "missing 'since'"),
  58         AttrError::MissingFeature => span_err!(diag, span, E0546, "missing 'feature'"),
  59         AttrError::MultipleStabilityLevels => span_err!(diag, span, E0544,
  60                                                         "multiple stability levels"),
  61         AttrError::UnsupportedLiteral => span_err!(diag, span, E0565, "unsupported literal"),
  62     }
  63 }
  64
  65 pub fn mark_used(attr: &Attribute) {
  66     debug!("Marking {:?} as used.", attr);
  67     let AttrId(id) = attr.id;
  68     USED_ATTRS.with(|slot| {
  69         let idx = (id / 64) as usize;
  70         let shift = id % 64;
  71         if slot.borrow().len() <= idx {
  72             slot.borrow_mut().resize(idx + 1, 0);
  73         }
  74         slot.borrow_mut()[idx] |= 1 << shift;
  75     });
  76 }
  77
  78 pub fn is_used(attr: &Attribute) -> bool {
  79     let AttrId(id) = attr.id;
  80     USED_ATTRS.with(|slot| {
  81         let idx = (id / 64) as usize;
  82         let shift = id % 64;
  83         slot.borrow().get(idx).map(|bits| bits & (1 << shift) != 0)
  84             .unwrap_or(false)
  85     })
  86 }
  87
  88 pub fn mark_known(attr: &Attribute) {
  89     debug!("Marking {:?} as known.", attr);
  90     let AttrId(id) = attr.id;
  91     KNOWN_ATTRS.with(|slot| {
  92         let idx = (id / 64) as usize;
  93         let shift = id % 64;
  94         if slot.borrow().len() <= idx {
  95             slot.borrow_mut().resize(idx + 1, 0);
  96         }
  97         slot.borrow_mut()[idx] |= 1 << shift;
  98     });
  99 }
 100
 101 pub fn is_known(attr: &Attribute) -> bool {
 102     let AttrId(id) = attr.id;
 103     KNOWN_ATTRS.with(|slot| {
 104         let idx = (id / 64) as usize;
 105         let shift = id % 64;
 106         slot.borrow().get(idx).map(|bits| bits & (1 << shift) != 0)
 107             .unwrap_or(false)
 108     })
 109 }
 110
 111 impl NestedMetaItem {
 112     /// Returns the MetaItem if self is a NestedMetaItemKind::MetaItem.
 113     pub fn meta_item(&self) -> Option<&MetaItem> {
 114         match self.node {
 115             NestedMetaItemKind::MetaItem(ref item) => Some(&item),
 116             _ => None
 117         }
 118     }
 119
 120     /// Returns the Lit if self is a NestedMetaItemKind::Literal.
 121     pub fn literal(&self) -> Option<&Lit> {
 122         match self.node {
 123             NestedMetaItemKind::Literal(ref lit) => Some(&lit),
 124             _ => None
 125         }
 126     }
 127
 128     /// Returns the Span for `self`.
 129     pub fn span(&self) -> Span {
 130         self.span
 131     }
 132
 133     /// Returns true if this list item is a MetaItem with a name of `name`.
 134     pub fn check_name(&self, name: &str) -> bool {
 135         self.meta_item().map_or(false, |meta_item| meta_item.check_name(name))
 136     }
 137
 138     /// Returns the name of the meta item, e.g. `foo` in `#[foo]`,
 139     /// `#[foo="bar"]` and `#[foo(bar)]`, if self is a MetaItem
 140     pub fn name(&self) -> Option<Name> {
 141         self.meta_item().and_then(|meta_item| Some(meta_item.name()))
 142     }
 143
 144     /// Gets the string value if self is a MetaItem and the MetaItem is a
 145     /// MetaItemKind::NameValue variant containing a string, otherwise None.
 146     pub fn value_str(&self) -> Option<Symbol> {
 147         self.meta_item().and_then(|meta_item| meta_item.value_str())
 148     }
 149
 150     /// Returns a name and single literal value tuple of the MetaItem.
 151     pub fn name_value_literal(&self) -> Option<(Name, &Lit)> {
 152         self.meta_item().and_then(
 153             |meta_item| meta_item.meta_item_list().and_then(
 154                 |meta_item_list| {
 155                     if meta_item_list.len() == 1 {
 156                         let nested_item = &meta_item_list[0];
 157                         if nested_item.is_literal() {
 158                             Some((meta_item.name(), nested_item.literal().unwrap()))
 159                         } else {
 160                             None
 161                         }
 162                     }
 163                     else {
 164                         None
 165                     }}))
 166     }
 167
 168     /// Returns a MetaItem if self is a MetaItem with Kind Word.
 169     pub fn word(&self) -> Option<&MetaItem> {
 170         self.meta_item().and_then(|meta_item| if meta_item.is_word() {
 171             Some(meta_item)
 172         } else {
 173             None
 174         })
 175     }
 176
 177     /// Gets a list of inner meta items from a list MetaItem type.
 178     pub fn meta_item_list(&self) -> Option<&[NestedMetaItem]> {
 179         self.meta_item().and_then(|meta_item| meta_item.meta_item_list())
 180     }
 181
 182     /// Returns `true` if the variant is MetaItem.
 183     pub fn is_meta_item(&self) -> bool {
 184         self.meta_item().is_some()
 185     }
 186
 187     /// Returns `true` if the variant is Literal.
 188     pub fn is_literal(&self) -> bool {
 189         self.literal().is_some()
 190     }
 191
 192     /// Returns `true` if self is a MetaItem and the meta item is a word.
 193     pub fn is_word(&self) -> bool {
 194         self.word().is_some()
 195     }
 196
 197     /// Returns `true` if self is a MetaItem and the meta item is a ValueString.
 198     pub fn is_value_str(&self) -> bool {
 199         self.value_str().is_some()
 200     }
 201
 202     /// Returns `true` if self is a MetaItem and the meta item is a list.
 203     pub fn is_meta_item_list(&self) -> bool {
 204         self.meta_item_list().is_some()
 205     }
 206 }
 207
 208 impl Attribute {
 209     pub fn check_name(&self, name: &str) -> bool {
 210         let matches = self.path == name;
 211         if matches {
 212             mark_used(self);
 213         }
 214         matches
 215     }
 216
 217     pub fn name(&self) -> Option<Name> {
 218         match self.path.segments.len() {
 219             1 => Some(self.path.segments[0].identifier.name),
 220             _ => None,
 221         }
 222     }
 223
 224     pub fn value_str(&self) -> Option<Symbol> {
 225         self.meta().and_then(|meta| meta.value_str())
 226     }
 227
 228     pub fn meta_item_list(&self) -> Option<Vec<NestedMetaItem>> {
 229         match self.meta() {
 230             Some(MetaItem { node: MetaItemKind::List(list), .. }) => Some(list),
 231             _ => None
 232         }
 233     }
 234
 235     pub fn is_word(&self) -> bool {
 236         self.path.segments.len() == 1 && self.tokens.is_empty()
 237     }
 238
 239     pub fn span(&self) -> Span {
 240         self.span
 241     }
 242
 243     pub fn is_meta_item_list(&self) -> bool {
 244         self.meta_item_list().is_some()
 245     }
 246
 247     /// Indicates if the attribute is a Value String.
 248     pub fn is_value_str(&self) -> bool {
 249         self.value_str().is_some()
 250     }
 251 }
 252
 253 impl MetaItem {
 254     pub fn name(&self) -> Name {
 255         self.name
 256     }
 257
 258     pub fn value_str(&self) -> Option<Symbol> {
 259         match self.node {
 260             MetaItemKind::NameValue(ref v) => {
 261                 match v.node {
 262                     LitKind::Str(ref s, _) => Some((*s).clone()),
 263                     _ => None,
 264                 }
 265             },
 266             _ => None
 267         }
 268     }
 269
 270     pub fn meta_item_list(&self) -> Option<&[NestedMetaItem]> {
 271         match self.node {
 272             MetaItemKind::List(ref l) => Some(&l[..]),
 273             _ => None
 274         }
 275     }
 276
 277     pub fn is_word(&self) -> bool {
 278         match self.node {
 279             MetaItemKind::Word => true,
 280             _ => false,
 281         }
 282     }
 283
 284     pub fn span(&self) -> Span { self.span }
 285
 286     pub fn check_name(&self, name: &str) -> bool {
 287         self.name() == name
 288     }
 289
 290     pub fn is_value_str(&self) -> bool {
 291         self.value_str().is_some()
 292     }
 293
 294     pub fn is_meta_item_list(&self) -> bool {
 295         self.meta_item_list().is_some()
 296     }
 297 }
 298
 299 impl Attribute {
 300     /// Extract the MetaItem from inside this Attribute.
 301     pub fn meta(&self) -> Option<MetaItem> {
 302         let mut tokens = self.tokens.trees().peekable();
 303         Some(MetaItem {
 304             name: match self.path.segments.len() {
 305                 1 => self.path.segments[0].identifier.name,
 306                 _ => return None,
 307             },
 308             node: if let Some(node) = MetaItemKind::from_tokens(&mut tokens) {
 309                 if tokens.peek().is_some() {
 310                     return None;
 311                 }
 312                 node
 313             } else {
 314                 return None;
 315             },
 316             span: self.span,
 317         })
 318     }
 319
 320     pub fn parse<'a, T, F>(&self, sess: &'a ParseSess, mut f: F) -> PResult<'a, T>
 321         where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
 322     {
 323         let mut parser = Parser::new(sess, self.tokens.clone(), None, false);
 324         let result = f(&mut parser)?;
 325         if parser.token != token::Eof {
 326             parser.unexpected()?;
 327         }
 328         Ok(result)
 329     }
 330
 331     pub fn parse_list<'a, T, F>(&self, sess: &'a ParseSess, mut f: F) -> PResult<'a, Vec<T>>
 332         where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
 333     {
 334         if self.tokens.is_empty() {
 335             return Ok(Vec::new());
 336         }
 337         self.parse(sess, |parser| {
 338             parser.expect(&token::OpenDelim(token::Paren))?;
 339             let mut list = Vec::new();
 340             while !parser.eat(&token::CloseDelim(token::Paren)) {
 341                 list.push(f(parser)?);
 342                 if !parser.eat(&token::Comma) {
 343                    parser.expect(&token::CloseDelim(token::Paren))?;
 344                     break
 345                 }
 346             }
 347             Ok(list)
 348         })
 349     }
 350
 351     pub fn parse_meta<'a>(&self, sess: &'a ParseSess) -> PResult<'a, MetaItem> {
 352         if self.path.segments.len() > 1 {
 353             sess.span_diagnostic.span_err(self.path.span, "expected ident, found path");
 354         }
 355
 356         Ok(MetaItem {
 357             name: self.path.segments.last().unwrap().identifier.name,
 358             node: self.parse(sess, |parser| parser.parse_meta_item_kind())?,
 359             span: self.span,
 360         })
 361     }
 362
 363     /// Convert self to a normal #[doc="foo"] comment, if it is a
 364     /// comment like `///` or `/** */`. (Returns self unchanged for
 365     /// non-sugared doc attributes.)
 366     pub fn with_desugared_doc<T, F>(&self, f: F) -> T where
 367         F: FnOnce(&Attribute) -> T,
 368     {
 369         if self.is_sugared_doc {
 370             let comment = self.value_str().unwrap();
 371             let meta = mk_name_value_item_str(
 372                 Symbol::intern("doc"),
 373                 Symbol::intern(&strip_doc_comment_decoration(&comment.as_str())));
 374             if self.style == ast::AttrStyle::Outer {
 375                 f(&mk_attr_outer(self.span, self.id, meta))
 376             } else {
 377                 f(&mk_attr_inner(self.span, self.id, meta))
 378             }
 379         } else {
 380             f(self)
 381         }
 382     }
 383 }
 384
 385 /* Constructors */
 386
 387 pub fn mk_name_value_item_str(name: Name, value: Symbol) -> MetaItem {
 388     let value_lit = dummy_spanned(LitKind::Str(value, ast::StrStyle::Cooked));
 389     mk_spanned_name_value_item(DUMMY_SP, name, value_lit)
 390 }
 391
 392 pub fn mk_name_value_item(name: Name, value: ast::Lit) -> MetaItem {
 393     mk_spanned_name_value_item(DUMMY_SP, name, value)
 394 }
 395
 396 pub fn mk_list_item(name: Name, items: Vec<NestedMetaItem>) -> MetaItem {
 397     mk_spanned_list_item(DUMMY_SP, name, items)
 398 }
 399
 400 pub fn mk_list_word_item(name: Name) -> ast::NestedMetaItem {
 401     dummy_spanned(NestedMetaItemKind::MetaItem(mk_spanned_word_item(DUMMY_SP, name)))
 402 }
 403
 404 pub fn mk_word_item(name: Name) -> MetaItem {
 405     mk_spanned_word_item(DUMMY_SP, name)
 406 }
 407
 408 pub fn mk_spanned_name_value_item(sp: Span, name: Name, value: ast::Lit) -> MetaItem {
 409     MetaItem { span: sp, name: name, node: MetaItemKind::NameValue(value) }
 410 }
 411
 412 pub fn mk_spanned_list_item(sp: Span, name: Name, items: Vec<NestedMetaItem>) -> MetaItem {
 413     MetaItem { span: sp, name: name, node: MetaItemKind::List(items) }
 414 }
 415
 416 pub fn mk_spanned_word_item(sp: Span, name: Name) -> MetaItem {
 417     MetaItem { span: sp, name: name, node: MetaItemKind::Word }
 418 }
 419
 420
 421
 422 thread_local! { static NEXT_ATTR_ID: Cell<usize> = Cell::new(0) }
 423
 424 pub fn mk_attr_id() -> AttrId {
 425     let id = NEXT_ATTR_ID.with(|slot| {
 426         let r = slot.get();
 427         slot.set(r + 1);
 428         r
 429     });
 430     AttrId(id)
 431 }
 432
 433 /// Returns an inner attribute with the given value.
 434 pub fn mk_attr_inner(span: Span, id: AttrId, item: MetaItem) -> Attribute {
 435     mk_spanned_attr_inner(span, id, item)
 436 }
 437
 438 /// Returns an innter attribute with the given value and span.
 439 pub fn mk_spanned_attr_inner(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
 440     Attribute {
 441         id: id,
 442         style: ast::AttrStyle::Inner,
 443         path: ast::Path::from_ident(item.span, ast::Ident::with_empty_ctxt(item.name)),
 444         tokens: item.node.tokens(item.span),
 445         is_sugared_doc: false,
 446         span: sp,
 447     }
 448 }
 449
 450
 451 /// Returns an outer attribute with the given value.
 452 pub fn mk_attr_outer(span: Span, id: AttrId, item: MetaItem) -> Attribute {
 453     mk_spanned_attr_outer(span, id, item)
 454 }
 455
 456 /// Returns an outer attribute with the given value and span.
 457 pub fn mk_spanned_attr_outer(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
 458     Attribute {
 459         id: id,
 460         style: ast::AttrStyle::Outer,
 461         path: ast::Path::from_ident(item.span, ast::Ident::with_empty_ctxt(item.name)),
 462         tokens: item.node.tokens(item.span),
 463         is_sugared_doc: false,
 464         span: sp,
 465     }
 466 }
 467
 468 pub fn mk_sugared_doc_attr(id: AttrId, text: Symbol, span: Span) -> Attribute {
 469     let style = doc_comment_style(&text.as_str());
 470     let lit = respan(span, LitKind::Str(text, ast::StrStyle::Cooked));
 471     Attribute {
 472         id: id,
 473         style: style,
 474         path: ast::Path::from_ident(span, ast::Ident::from_str("doc")),
 475         tokens: MetaItemKind::NameValue(lit).tokens(span),
 476         is_sugared_doc: true,
 477         span: span,
 478     }
 479 }
 480
 481 pub fn list_contains_name(items: &[NestedMetaItem], name: &str) -> bool {
 482     items.iter().any(|item| {
 483         item.check_name(name)
 484     })
 485 }
 486
 487 pub fn contains_name(attrs: &[Attribute], name: &str) -> bool {
 488     attrs.iter().any(|item| {
 489         item.check_name(name)
 490     })
 491 }
 492
 493 pub fn first_attr_value_str_by_name(attrs: &[Attribute], name: &str) -> Option<Symbol> {
 494     attrs.iter()
 495         .find(|at| at.check_name(name))
 496         .and_then(|at| at.value_str())
 497 }
 498
 499 /* Higher-level applications */
 500
 501 pub fn find_crate_name(attrs: &[Attribute]) -> Option<Symbol> {
 502     first_attr_value_str_by_name(attrs, "crate_name")
 503 }
 504
 505 /// Find the value of #[export_name=*] attribute and check its validity.
 506 pub fn find_export_name_attr(diag: &Handler, attrs: &[Attribute]) -> Option<Symbol> {
 507     attrs.iter().fold(None, |ia,attr| {
 508         if attr.check_name("export_name") {
 509             if let s@Some(_) = attr.value_str() {
 510                 s
 511             } else {
 512                 struct_span_err!(diag, attr.span, E0558,
 513                                  "export_name attribute has invalid format")
 514                     .span_label(attr.span,
 515                                 &format!("did you mean #[export_name=\"*\"]?"))
 516                     .emit();
 517                 None
 518             }
 519         } else {
 520             ia
 521         }
 522     })
 523 }
 524
 525 pub fn contains_extern_indicator(diag: &Handler, attrs: &[Attribute]) -> bool {
 526     contains_name(attrs, "no_mangle") ||
 527         find_export_name_attr(diag, attrs).is_some()
 528 }
 529
 530 #[derive(Copy, Clone, PartialEq)]
 531 pub enum InlineAttr {
 532     None,
 533     Hint,
 534     Always,
 535     Never,
 536 }
 537
 538 /// Determine what `#[inline]` attribute is present in `attrs`, if any.
 539 pub fn find_inline_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> InlineAttr {
 540     attrs.iter().fold(InlineAttr::None, |ia, attr| {
 541         if attr.path != "inline" {
 542             return ia;
 543         }
 544         let meta = match attr.meta() {
 545             Some(meta) => meta.node,
 546             None => return ia,
 547         };
 548         match meta {
 549             MetaItemKind::Word => {
 550                 mark_used(attr);
 551                 InlineAttr::Hint
 552             }
 553             MetaItemKind::List(ref items) => {
 554                 mark_used(attr);
 555                 if items.len() != 1 {
 556                     diagnostic.map(|d|{ span_err!(d, attr.span, E0534, "expected one argument"); });
 557                     InlineAttr::None
 558                 } else if list_contains_name(&items[..], "always") {
 559                     InlineAttr::Always
 560                 } else if list_contains_name(&items[..], "never") {
 561                     InlineAttr::Never
 562                 } else {
 563                     diagnostic.map(|d| {
 564                         span_err!(d, items[0].span, E0535, "invalid argument");
 565                     });
 566
 567                     InlineAttr::None
 568                 }
 569             }
 570             _ => ia,
 571         }
 572     })
 573 }
 574
 575 /// True if `#[inline]` or `#[inline(always)]` is present in `attrs`.
 576 pub fn requests_inline(attrs: &[Attribute]) -> bool {
 577     match find_inline_attr(None, attrs) {
 578         InlineAttr::Hint | InlineAttr::Always => true,
 579         InlineAttr::None | InlineAttr::Never => false,
 580     }
 581 }
 582
 583 /// Tests if a cfg-pattern matches the cfg set
 584 pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Features>) -> bool {
 585     match cfg.node {
 586         ast::MetaItemKind::List(ref mis) => {
 587             for mi in mis.iter() {
 588                 if !mi.is_meta_item() {
 589                     handle_errors(&sess.span_diagnostic, mi.span, AttrError::UnsupportedLiteral);
 590                     return false;
 591                 }
 592             }
 593
 594             // The unwraps below may look dangerous, but we've already asserted
 595             // that they won't fail with the loop above.
 596             match &*cfg.name.as_str() {
 597                 "any" => mis.iter().any(|mi| {
 598                     cfg_matches(mi.meta_item().unwrap(), sess, features)
 599                 }),
 600                 "all" => mis.iter().all(|mi| {
 601                     cfg_matches(mi.meta_item().unwrap(), sess, features)
 602                 }),
 603                 "not" => {
 604                     if mis.len() != 1 {
 605                         span_err!(sess.span_diagnostic, cfg.span, E0536, "expected 1 cfg-pattern");
 606                         return false;
 607                     }
 608
 609                     !cfg_matches(mis[0].meta_item().unwrap(), sess, features)
 610                 },
 611                 p => {
 612                     span_err!(sess.span_diagnostic, cfg.span, E0537, "invalid predicate `{}`", p);
 613                     false
 614                 }
 615             }
 616         },
 617         ast::MetaItemKind::Word | ast::MetaItemKind::NameValue(..) => {
 618             if let (Some(feats), Some(gated_cfg)) = (features, GatedCfg::gate(cfg)) {
 619                 gated_cfg.check_and_emit(sess, feats);
 620             }
 621             sess.config.contains(&(cfg.name(), cfg.value_str()))
 622         }
 623     }
 624 }
 625
 626 /// Represents the #[stable], #[unstable] and #[rustc_deprecated] attributes.
 627 #[derive(RustcEncodable, RustcDecodable, Clone, Debug, PartialEq, Eq, Hash)]
 628 pub struct Stability {
 629     pub level: StabilityLevel,
 630     pub feature: Symbol,
 631     pub rustc_depr: Option<RustcDeprecation>,
 632 }
 633
 634 /// The available stability levels.
 635 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 636 pub enum StabilityLevel {
 637     // Reason for the current stability level and the relevant rust-lang issue
 638     Unstable { reason: Option<Symbol>, issue: u32 },
 639     Stable { since: Symbol },
 640 }
 641
 642 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 643 pub struct RustcDeprecation {
 644     pub since: Symbol,
 645     pub reason: Symbol,
 646 }
 647
 648 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 649 pub struct Deprecation {
 650     pub since: Option<Symbol>,
 651     pub note: Option<Symbol>,
 652 }
 653
 654 impl StabilityLevel {
 655     pub fn is_unstable(&self) -> bool { if let Unstable {..} = *self { true } else { false }}
 656     pub fn is_stable(&self) -> bool { if let Stable {..} = *self { true } else { false }}
 657 }
 658
 659 fn find_stability_generic<'a, I>(diagnostic: &Handler,
 660                                  attrs_iter: I,
 661                                  item_sp: Span)
 662                                  -> Option<Stability>
 663     where I: Iterator<Item = &'a Attribute>
 664 {
 665     let mut stab: Option<Stability> = None;
 666     let mut rustc_depr: Option<RustcDeprecation> = None;
 667
 668     'outer: for attr in attrs_iter {
 669         if attr.path != "rustc_deprecated" && attr.path != "unstable" && attr.path != "stable" {
 670             continue // not a stability level
 671         }
 672
 673         mark_used(attr);
 674
 675         let meta = attr.meta();
 676         if let Some(MetaItem { node: MetaItemKind::List(ref metas), .. }) = meta {
 677             let meta = meta.as_ref().unwrap();
 678             let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
 679                 if item.is_some() {
 680                     handle_errors(diagnostic, meta.span, AttrError::MultipleItem(meta.name()));
 681                     return false
 682                 }
 683                 if let Some(v) = meta.value_str() {
 684                     *item = Some(v);
 685                     true
 686                 } else {
 687                     span_err!(diagnostic, meta.span, E0539, "incorrect meta item");
 688                     false
 689                 }
 690             };
 691
 692             match &*meta.name.as_str() {
 693                 "rustc_deprecated" => {
 694                     if rustc_depr.is_some() {
 695                         span_err!(diagnostic, item_sp, E0540,
 696                                   "multiple rustc_deprecated attributes");
 697                         break
 698                     }
 699
 700                     let mut since = None;
 701                     let mut reason = None;
 702                     for meta in metas {
 703                         if let Some(mi) = meta.meta_item() {
 704                             match &*mi.name().as_str() {
 705                                 "since" => if !get(mi, &mut since) { continue 'outer },
 706                                 "reason" => if !get(mi, &mut reason) { continue 'outer },
 707                                 _ => {
 708                                     handle_errors(diagnostic, mi.span,
 709                                                   AttrError::UnknownMetaItem(mi.name()));
 710                                     continue 'outer
 711                                 }
 712                             }
 713                         } else {
 714                             handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
 715                             continue 'outer
 716                         }
 717                     }
 718
 719                     match (since, reason) {
 720                         (Some(since), Some(reason)) => {
 721                             rustc_depr = Some(RustcDeprecation {
 722                                 since: since,
 723                                 reason: reason,
 724                             })
 725                         }
 726                         (None, _) => {
 727                             handle_errors(diagnostic, attr.span(), AttrError::MissingSince);
 728                             continue
 729                         }
 730                         _ => {
 731                             span_err!(diagnostic, attr.span(), E0543, "missing 'reason'");
 732                             continue
 733                         }
 734                     }
 735                 }
 736                 "unstable" => {
 737                     if stab.is_some() {
 738                         handle_errors(diagnostic, attr.span(), AttrError::MultipleStabilityLevels);
 739                         break
 740                     }
 741
 742                     let mut feature = None;
 743                     let mut reason = None;
 744                     let mut issue = None;
 745                     for meta in metas {
 746                         if let Some(mi) = meta.meta_item() {
 747                             match &*mi.name().as_str() {
 748                                 "feature" => if !get(mi, &mut feature) { continue 'outer },
 749                                 "reason" => if !get(mi, &mut reason) { continue 'outer },
 750                                 "issue" => if !get(mi, &mut issue) { continue 'outer },
 751                                 _ => {
 752                                     handle_errors(diagnostic, meta.span,
 753                                                   AttrError::UnknownMetaItem(mi.name()));
 754                                     continue 'outer
 755                                 }
 756                             }
 757                         } else {
 758                             handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
 759                             continue 'outer
 760                         }
 761                     }
 762
 763                     match (feature, reason, issue) {
 764                         (Some(feature), reason, Some(issue)) => {
 765                             stab = Some(Stability {
 766                                 level: Unstable {
 767                                     reason: reason,
 768                                     issue: {
 769                                         if let Ok(issue) = issue.as_str().parse() {
 770                                             issue
 771                                         } else {
 772                                             span_err!(diagnostic, attr.span(), E0545,
 773                                                       "incorrect 'issue'");
 774                                             continue
 775                                         }
 776                                     }
 777                                 },
 778                                 feature: feature,
 779                                 rustc_depr: None,
 780                             })
 781                         }
 782                         (None, _, _) => {
 783                             handle_errors(diagnostic, attr.span(), AttrError::MissingFeature);
 784                             continue
 785                         }
 786                         _ => {
 787                             span_err!(diagnostic, attr.span(), E0547, "missing 'issue'");
 788                             continue
 789                         }
 790                     }
 791                 }
 792                 "stable" => {
 793                     if stab.is_some() {
 794                         handle_errors(diagnostic, attr.span(), AttrError::MultipleStabilityLevels);
 795                         break
 796                     }
 797
 798                     let mut feature = None;
 799                     let mut since = None;
 800                     for meta in metas {
 801                         if let NestedMetaItemKind::MetaItem(ref mi) = meta.node {
 802                             match &*mi.name().as_str() {
 803                                 "feature" => if !get(mi, &mut feature) { continue 'outer },
 804                                 "since" => if !get(mi, &mut since) { continue 'outer },
 805                                 _ => {
 806                                     handle_errors(diagnostic, meta.span,
 807                                                   AttrError::UnknownMetaItem(mi.name()));
 808                                     continue 'outer
 809                                 }
 810                             }
 811                         } else {
 812                             handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
 813                             continue 'outer
 814                         }
 815                     }
 816
 817                     match (feature, since) {
 818                         (Some(feature), Some(since)) => {
 819                             stab = Some(Stability {
 820                                 level: Stable {
 821                                     since: since,
 822                                 },
 823                                 feature: feature,
 824                                 rustc_depr: None,
 825                             })
 826                         }
 827                         (None, _) => {
 828                             handle_errors(diagnostic, attr.span(), AttrError::MissingFeature);
 829                             continue
 830                         }
 831                         _ => {
 832                             handle_errors(diagnostic, attr.span(), AttrError::MissingSince);
 833                             continue
 834                         }
 835                     }
 836                 }
 837                 _ => unreachable!()
 838             }
 839         } else {
 840             span_err!(diagnostic, attr.span(), E0548, "incorrect stability attribute type");
 841             continue
 842         }
 843     }
 844
 845     // Merge the deprecation info into the stability info
 846     if let Some(rustc_depr) = rustc_depr {
 847         if let Some(ref mut stab) = stab {
 848             stab.rustc_depr = Some(rustc_depr);
 849         } else {
 850             span_err!(diagnostic, item_sp, E0549,
 851                       "rustc_deprecated attribute must be paired with \
 852                        either stable or unstable attribute");
 853         }
 854     }
 855
 856     stab
 857 }
 858
 859 fn find_deprecation_generic<'a, I>(diagnostic: &Handler,
 860                                    attrs_iter: I,
 861                                    item_sp: Span)
 862                                    -> Option<Deprecation>
 863     where I: Iterator<Item = &'a Attribute>
 864 {
 865     let mut depr: Option<Deprecation> = None;
 866
 867     'outer: for attr in attrs_iter {
 868         if attr.path != "deprecated" {
 869             continue
 870         }
 871
 872         mark_used(attr);
 873
 874         if depr.is_some() {
 875             span_err!(diagnostic, item_sp, E0550, "multiple deprecated attributes");
 876             break
 877         }
 878
 879         depr = if let Some(metas) = attr.meta_item_list() {
 880             let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
 881                 if item.is_some() {
 882                     handle_errors(diagnostic, meta.span, AttrError::MultipleItem(meta.name()));
 883                     return false
 884                 }
 885                 if let Some(v) = meta.value_str() {
 886                     *item = Some(v);
 887                     true
 888                 } else {
 889                     span_err!(diagnostic, meta.span, E0551, "incorrect meta item");
 890                     false
 891                 }
 892             };
 893
 894             let mut since = None;
 895             let mut note = None;
 896             for meta in metas {
 897                 if let NestedMetaItemKind::MetaItem(ref mi) = meta.node {
 898                     match &*mi.name().as_str() {
 899                         "since" => if !get(mi, &mut since) { continue 'outer },
 900                         "note" => if !get(mi, &mut note) { continue 'outer },
 901                         _ => {
 902                             handle_errors(diagnostic, meta.span,
 903                                           AttrError::UnknownMetaItem(mi.name()));
 904                             continue 'outer
 905                         }
 906                     }
 907                 } else {
 908                     handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
 909                     continue 'outer
 910                 }
 911             }
 912
 913             Some(Deprecation {since: since, note: note})
 914         } else {
 915             Some(Deprecation{since: None, note: None})
 916         }
 917     }
 918
 919     depr
 920 }
 921
 922 /// Find the first stability attribute. `None` if none exists.
 923 pub fn find_stability(diagnostic: &Handler, attrs: &[Attribute],
 924                       item_sp: Span) -> Option<Stability> {
 925     find_stability_generic(diagnostic, attrs.iter(), item_sp)
 926 }
 927
 928 /// Find the deprecation attribute. `None` if none exists.
 929 pub fn find_deprecation(diagnostic: &Handler, attrs: &[Attribute],
 930                         item_sp: Span) -> Option<Deprecation> {
 931     find_deprecation_generic(diagnostic, attrs.iter(), item_sp)
 932 }
 933
 934
 935 /// Parse #[repr(...)] forms.
 936 ///
 937 /// Valid repr contents: any of the primitive integral type names (see
 938 /// `int_type_of_word`, below) to specify enum discriminant type; `C`, to use
 939 /// the same discriminant size that the corresponding C enum would or C
 940 /// structure layout, and `packed` to remove padding.
 941 pub fn find_repr_attrs(diagnostic: &Handler, attr: &Attribute) -> Vec<ReprAttr> {
 942     let mut acc = Vec::new();
 943     if attr.path == "repr" {
 944         if let Some(items) = attr.meta_item_list() {
 945             mark_used(attr);
 946             for item in items {
 947                 if !item.is_meta_item() {
 948                     handle_errors(diagnostic, item.span, AttrError::UnsupportedLiteral);
 949                     continue
 950                 }
 951
 952                 let mut recognised = false;
 953                 if let Some(mi) = item.word() {
 954                     let word = &*mi.name().as_str();
 955                     let hint = match word {
 956                         // Can't use "extern" because it's not a lexical identifier.
 957                         "C" => Some(ReprExtern),
 958                         "packed" => Some(ReprPacked),
 959                         "simd" => Some(ReprSimd),
 960                         _ => match int_type_of_word(word) {
 961                             Some(ity) => Some(ReprInt(ity)),
 962                             None => {
 963                                 None
 964                             }
 965                         }
 966                     };
 967
 968                     if let Some(h) = hint {
 969                         recognised = true;
 970                         acc.push(h);
 971                     }
 972                 } else if let Some((name, value)) = item.name_value_literal() {
 973                     if name == "align" {
 974                         recognised = true;
 975                         let mut align_error = None;
 976                         if let ast::LitKind::Int(align, ast::LitIntType::Unsuffixed) = value.node {
 977                             if align.is_power_of_two() {
 978                                 // rustc::ty::layout::Align restricts align to <= 32768
 979                                 if align <= 32768 {
 980                                     acc.push(ReprAlign(align as u16));
 981                                 } else {
 982                                     align_error = Some("larger than 32768");
 983                                 }
 984                             } else {
 985                                 align_error = Some("not a power of two");
 986                             }
 987                         } else {
 988                             align_error = Some("not an unsuffixed integer");
 989                         }
 990                         if let Some(align_error) = align_error {
 991                             span_err!(diagnostic, item.span, E0589,
 992                                       "invalid `repr(align)` attribute: {}", align_error);
 993                         }
 994                     }
 995                 }
 996                 if !recognised {
 997                     // Not a word we recognize
 998                     span_err!(diagnostic, item.span, E0552,
 999                               "unrecognized representation hint");
1000                 }
1001             }
1002         }
1003     }
1004     acc
1005 }
1006
1007 fn int_type_of_word(s: &str) -> Option<IntType> {
1008     match s {
1009         "i8" => Some(SignedInt(ast::IntTy::I8)),
1010         "u8" => Some(UnsignedInt(ast::UintTy::U8)),
1011         "i16" => Some(SignedInt(ast::IntTy::I16)),
1012         "u16" => Some(UnsignedInt(ast::UintTy::U16)),
1013         "i32" => Some(SignedInt(ast::IntTy::I32)),
1014         "u32" => Some(UnsignedInt(ast::UintTy::U32)),
1015         "i64" => Some(SignedInt(ast::IntTy::I64)),
1016         "u64" => Some(UnsignedInt(ast::UintTy::U64)),
1017         "i128" => Some(SignedInt(ast::IntTy::I128)),
1018         "u128" => Some(UnsignedInt(ast::UintTy::U128)),
1019         "isize" => Some(SignedInt(ast::IntTy::Is)),
1020         "usize" => Some(UnsignedInt(ast::UintTy::Us)),
1021         _ => None
1022     }
1023 }
1024
1025 #[derive(PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
1026 pub enum ReprAttr {
1027     ReprInt(IntType),
1028     ReprExtern,
1029     ReprPacked,
1030     ReprSimd,
1031     ReprAlign(u16),
1032 }
1033
1034 #[derive(Eq, Hash, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
1035 pub enum IntType {
1036     SignedInt(ast::IntTy),
1037     UnsignedInt(ast::UintTy)
1038 }
1039
1040 impl IntType {
1041     #[inline]
1042     pub fn is_signed(self) -> bool {
1043         match self {
1044             SignedInt(..) => true,
1045             UnsignedInt(..) => false
1046         }
1047     }
1048 }
1049
1050 impl MetaItem {
1051     fn tokens(&self) -> TokenStream {
1052         let ident = TokenTree::Token(self.span, Token::Ident(Ident::with_empty_ctxt(self.name)));
1053         TokenStream::concat(vec![ident.into(), self.node.tokens(self.span)])
1054     }
1055
1056     fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<MetaItem>
1057         where I: Iterator<Item = TokenTree>,
1058     {
1059         let (mut span, name) = match tokens.next() {
1060             Some(TokenTree::Token(span, Token::Ident(ident))) => (span, ident.name),
1061             Some(TokenTree::Token(_, Token::Interpolated(ref nt))) => match **nt {
1062                 token::Nonterminal::NtIdent(ident) => (ident.span, ident.node.name),
1063                 token::Nonterminal::NtMeta(ref meta) => return Some(meta.clone()),
1064                 _ => return None,
1065             },
1066             _ => return None,
1067         };
1068         let node = match MetaItemKind::from_tokens(tokens) {
1069             Some(node) => node,
1070             _ => return None,
1071         };
1072         if let Some(last_span) = node.last_span() {
1073             span.hi = last_span.hi;
1074         }
1075         Some(MetaItem { name: name, span: span, node: node })
1076     }
1077 }
1078
1079 impl MetaItemKind {
1080     fn last_span(&self) -> Option<Span> {
1081         match *self {
1082             MetaItemKind::Word => None,
1083             MetaItemKind::List(ref list) => list.last().map(NestedMetaItem::span),
1084             MetaItemKind::NameValue(ref lit) => Some(lit.span),
1085         }
1086     }
1087
1088     pub fn tokens(&self, span: Span) -> TokenStream {
1089         match *self {
1090             MetaItemKind::Word => TokenStream::empty(),
1091             MetaItemKind::NameValue(ref lit) => {
1092                 TokenStream::concat(vec![TokenTree::Token(span, Token::Eq).into(), lit.tokens()])
1093             }
1094             MetaItemKind::List(ref list) => {
1095                 let mut tokens = Vec::new();
1096                 for (i, item) in list.iter().enumerate() {
1097                     if i > 0 {
1098                         tokens.push(TokenTree::Token(span, Token::Comma).into());
1099                     }
1100                     tokens.push(item.node.tokens());
1101                 }
1102                 TokenTree::Delimited(span, Delimited {
1103                     delim: token::Paren,
1104                     tts: TokenStream::concat(tokens).into(),
1105                 }).into()
1106             }
1107         }
1108     }
1109
1110     fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<MetaItemKind>
1111         where I: Iterator<Item = TokenTree>,
1112     {
1113         let delimited = match tokens.peek().cloned() {
1114             Some(TokenTree::Token(_, token::Eq)) => {
1115                 tokens.next();
1116                 return if let Some(TokenTree::Token(span, token)) = tokens.next() {
1117                     LitKind::from_token(token)
1118                         .map(|lit| MetaItemKind::NameValue(Spanned { node: lit, span: span }))
1119                 } else {
1120                     None
1121                 };
1122             }
1123             Some(TokenTree::Delimited(_, ref delimited)) if delimited.delim == token::Paren => {
1124                 tokens.next();
1125                 delimited.stream()
1126             }
1127             _ => return Some(MetaItemKind::Word),
1128         };
1129
1130         let mut tokens = delimited.into_trees().peekable();
1131         let mut result = Vec::new();
1132         while let Some(..) = tokens.peek() {
1133             match NestedMetaItemKind::from_tokens(&mut tokens) {
1134                 Some(item) => result.push(Spanned { span: item.span(), node: item }),
1135                 None => return None,
1136             }
1137             match tokens.next() {
1138                 None | Some(TokenTree::Token(_, Token::Comma)) => {}
1139                 _ => return None,
1140             }
1141         }
1142         Some(MetaItemKind::List(result))
1143     }
1144 }
1145
1146 impl NestedMetaItemKind {
1147     fn span(&self) -> Span {
1148         match *self {
1149             NestedMetaItemKind::MetaItem(ref item) => item.span,
1150             NestedMetaItemKind::Literal(ref lit) => lit.span,
1151         }
1152     }
1153
1154     fn tokens(&self) -> TokenStream {
1155         match *self {
1156             NestedMetaItemKind::MetaItem(ref item) => item.tokens(),
1157             NestedMetaItemKind::Literal(ref lit) => lit.tokens(),
1158         }
1159     }
1160
1161     fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<NestedMetaItemKind>
1162         where I: Iterator<Item = TokenTree>,
1163     {
1164         if let Some(TokenTree::Token(span, token)) = tokens.peek().cloned() {
1165             if let Some(node) = LitKind::from_token(token) {
1166                 tokens.next();
1167                 return Some(NestedMetaItemKind::Literal(Spanned { node: node, span: span }));
1168             }
1169         }
1170
1171         MetaItem::from_tokens(tokens).map(NestedMetaItemKind::MetaItem)
1172     }
1173 }
1174
1175 impl Lit {
1176     fn tokens(&self) -> TokenStream {
1177         TokenTree::Token(self.span, self.node.token()).into()
1178     }
1179 }
1180
1181 impl LitKind {
1182     fn token(&self) -> Token {
1183         use std::ascii;
1184
1185         match *self {
1186             LitKind::Str(string, ast::StrStyle::Cooked) => {
1187                 let mut escaped = String::new();
1188                 for ch in string.as_str().chars() {
1189                     escaped.extend(ch.escape_unicode());
1190                 }
1191                 Token::Literal(token::Lit::Str_(Symbol::intern(&escaped)), None)
1192             }
1193             LitKind::Str(string, ast::StrStyle::Raw(n)) => {
1194                 Token::Literal(token::Lit::StrRaw(string, n), None)
1195             }
1196             LitKind::ByteStr(ref bytes) => {
1197                 let string = bytes.iter().cloned().flat_map(ascii::escape_default)
1198                     .map(Into::<char>::into).collect::<String>();
1199                 Token::Literal(token::Lit::ByteStr(Symbol::intern(&string)), None)
1200             }
1201             LitKind::Byte(byte) => {
1202                 let string: String = ascii::escape_default(byte).map(Into::<char>::into).collect();
1203                 Token::Literal(token::Lit::Byte(Symbol::intern(&string)), None)
1204             }
1205             LitKind::Char(ch) => {
1206                 let string: String = ch.escape_default().map(Into::<char>::into).collect();
1207                 Token::Literal(token::Lit::Char(Symbol::intern(&string)), None)
1208             }
1209             LitKind::Int(n, ty) => {
1210                 let suffix = match ty {
1211                     ast::LitIntType::Unsigned(ty) => Some(Symbol::intern(ty.ty_to_string())),
1212                     ast::LitIntType::Signed(ty) => Some(Symbol::intern(ty.ty_to_string())),
1213                     ast::LitIntType::Unsuffixed => None,
1214                 };
1215                 Token::Literal(token::Lit::Integer(Symbol::intern(&n.to_string())), suffix)
1216             }
1217             LitKind::Float(symbol, ty) => {
1218                 Token::Literal(token::Lit::Float(symbol), Some(Symbol::intern(ty.ty_to_string())))
1219             }
1220             LitKind::FloatUnsuffixed(symbol) => Token::Literal(token::Lit::Float(symbol), None),
1221             LitKind::Bool(value) => Token::Ident(Ident::with_empty_ctxt(Symbol::intern(match value {
1222                 true => "true",
1223                 false => "false",
1224             }))),
1225         }
1226     }
1227
1228     fn from_token(token: Token) -> Option<LitKind> {
1229         match token {
1230             Token::Ident(ident) if ident.name == "true" => Some(LitKind::Bool(true)),
1231             Token::Ident(ident) if ident.name == "false" => Some(LitKind::Bool(false)),
1232             Token::Interpolated(ref nt) => match **nt {
1233                 token::NtExpr(ref v) => match v.node {
1234                     ExprKind::Lit(ref lit) => Some(lit.node.clone()),
1235                     _ => None,
1236                 },
1237                 _ => None,
1238             },
1239             Token::Literal(lit, suf) => {
1240                 let (suffix_illegal, result) = parse::lit_token(lit, suf, None);
1241                 if suffix_illegal && suf.is_some() {
1242                     return None;
1243                 }
1244                 result
1245             }
1246             _ => None,
1247         }
1248     }
1249 }
1250
1251 pub trait HasAttrs: Sized {
1252     fn attrs(&self) -> &[ast::Attribute];
1253     fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self;
1254 }
1255
1256 impl<T: HasAttrs> HasAttrs for Spanned<T> {
1257     fn attrs(&self) -> &[ast::Attribute] { self.node.attrs() }
1258     fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self {
1259         Spanned { node: self.node.map_attrs(f), span: self.span }
1260     }
1261 }
1262
1263 impl HasAttrs for Vec<Attribute> {
1264     fn attrs(&self) -> &[Attribute] {
1265         &self
1266     }
1267     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
1268         f(self)
1269     }
1270 }
1271
1272 impl HasAttrs for ThinVec<Attribute> {
1273     fn attrs(&self) -> &[Attribute] {
1274         &self
1275     }
1276     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
1277         f(self.into()).into()
1278     }
1279 }
1280
1281 impl<T: HasAttrs + 'static> HasAttrs for P<T> {
1282     fn attrs(&self) -> &[Attribute] {
1283         (**self).attrs()
1284     }
1285     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
1286         self.map(|t| t.map_attrs(f))
1287     }
1288 }
1289
1290 impl HasAttrs for StmtKind {
1291     fn attrs(&self) -> &[Attribute] {
1292         match *self {
1293             StmtKind::Local(ref local) => local.attrs(),
1294             StmtKind::Item(..) => &[],
1295             StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => expr.attrs(),
1296             StmtKind::Mac(ref mac) => {
1297                 let (_, _, ref attrs) = **mac;
1298                 attrs.attrs()
1299             }
1300         }
1301     }
1302
1303     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
1304         match self {
1305             StmtKind::Local(local) => StmtKind::Local(local.map_attrs(f)),
1306             StmtKind::Item(..) => self,
1307             StmtKind::Expr(expr) => StmtKind::Expr(expr.map_attrs(f)),
1308             StmtKind::Semi(expr) => StmtKind::Semi(expr.map_attrs(f)),
1309             StmtKind::Mac(mac) => StmtKind::Mac(mac.map(|(mac, style, attrs)| {
1310                 (mac, style, attrs.map_attrs(f))
1311             })),
1312         }
1313     }
1314 }
1315
1316 impl HasAttrs for Stmt {
1317     fn attrs(&self) -> &[ast::Attribute] { self.node.attrs() }
1318     fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self {
1319         Stmt { id: self.id, node: self.node.map_attrs(f), span: self.span }
1320     }
1321 }
1322
1323 macro_rules! derive_has_attrs {
1324     ($($ty:path),*) => { $(
1325         impl HasAttrs for $ty {
1326             fn attrs(&self) -> &[Attribute] {
1327                 &self.attrs
1328             }
1329
1330             fn map_attrs<F>(mut self, f: F) -> Self
1331                 where F: FnOnce(Vec<Attribute>) -> Vec<Attribute>,
1332             {
1333                 self.attrs = self.attrs.map_attrs(f);
1334                 self
1335             }
1336         }
1337     )* }
1338 }
1339
1340 derive_has_attrs! {
1341     Item, Expr, Local, ast::ForeignItem, ast::StructField, ast::ImplItem, ast::TraitItem, ast::Arm,
1342     ast::Field, ast::FieldPat, ast::Variant_
1343 }