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 use GLOBALS;
  34
  35 use std::iter;
  36
  37 enum AttrError {
  38     MultipleItem(Name),
  39     UnknownMetaItem(Name),
  40     MissingSince,
  41     MissingFeature,
  42     MultipleStabilityLevels,
  43     UnsupportedLiteral
  44 }
  45
  46 fn handle_errors(diag: &Handler, span: Span, error: AttrError) {
  47     match error {
  48         AttrError::MultipleItem(item) => span_err!(diag, span, E0538,
  49                                                    "multiple '{}' items", item),
  50         AttrError::UnknownMetaItem(item) => span_err!(diag, span, E0541,
  51                                                       "unknown meta item '{}'", item),
  52         AttrError::MissingSince => span_err!(diag, span, E0542, "missing 'since'"),
  53         AttrError::MissingFeature => span_err!(diag, span, E0546, "missing 'feature'"),
  54         AttrError::MultipleStabilityLevels => span_err!(diag, span, E0544,
  55                                                         "multiple stability levels"),
  56         AttrError::UnsupportedLiteral => span_err!(diag, span, E0565, "unsupported literal"),
  57     }
  58 }
  59
  60 pub fn mark_used(attr: &Attribute) {
  61     debug!("Marking {:?} as used.", attr);
  62     let AttrId(id) = attr.id;
  63     GLOBALS.with(|globals| {
  64         let mut slot = globals.used_attrs.lock();
  65         let idx = (id / 64) as usize;
  66         let shift = id % 64;
  67         if slot.len() <= idx {
  68             slot.resize(idx + 1, 0);
  69         }
  70         slot[idx] |= 1 << shift;
  71     });
  72 }
  73
  74 pub fn is_used(attr: &Attribute) -> bool {
  75     let AttrId(id) = attr.id;
  76     GLOBALS.with(|globals| {
  77         let slot = globals.used_attrs.lock();
  78         let idx = (id / 64) as usize;
  79         let shift = id % 64;
  80         slot.get(idx).map(|bits| bits & (1 << shift) != 0)
  81             .unwrap_or(false)
  82     })
  83 }
  84
  85 pub fn mark_known(attr: &Attribute) {
  86     debug!("Marking {:?} as known.", attr);
  87     let AttrId(id) = attr.id;
  88     GLOBALS.with(|globals| {
  89         let mut slot = globals.known_attrs.lock();
  90         let idx = (id / 64) as usize;
  91         let shift = id % 64;
  92         if slot.len() <= idx {
  93             slot.resize(idx + 1, 0);
  94         }
  95         slot[idx] |= 1 << shift;
  96     });
  97 }
  98
  99 pub fn is_known(attr: &Attribute) -> bool {
 100     let AttrId(id) = attr.id;
 101     GLOBALS.with(|globals| {
 102         let slot = globals.known_attrs.lock();
 103         let idx = (id / 64) as usize;
 104         let shift = id % 64;
 105         slot.get(idx).map(|bits| bits & (1 << shift) != 0)
 106             .unwrap_or(false)
 107     })
 108 }
 109
 110 impl NestedMetaItem {
 111     /// Returns the MetaItem if self is a NestedMetaItemKind::MetaItem.
 112     pub fn meta_item(&self) -> Option<&MetaItem> {
 113         match self.node {
 114             NestedMetaItemKind::MetaItem(ref item) => Some(item),
 115             _ => None
 116         }
 117     }
 118
 119     /// Returns the Lit if self is a NestedMetaItemKind::Literal.
 120     pub fn literal(&self) -> Option<&Lit> {
 121         match self.node {
 122             NestedMetaItemKind::Literal(ref lit) => Some(lit),
 123             _ => None
 124         }
 125     }
 126
 127     /// Returns the Span for `self`.
 128     pub fn span(&self) -> Span {
 129         self.span
 130     }
 131
 132     /// Returns true if this list item is a MetaItem with a name of `name`.
 133     pub fn check_name(&self, name: &str) -> bool {
 134         self.meta_item().map_or(false, |meta_item| meta_item.check_name(name))
 135     }
 136
 137     /// Returns the name of the meta item, e.g. `foo` in `#[foo]`,
 138     /// `#[foo="bar"]` and `#[foo(bar)]`, if self is a MetaItem
 139     pub fn name(&self) -> Option<Name> {
 140         self.meta_item().and_then(|meta_item| Some(meta_item.name()))
 141     }
 142
 143     /// Gets the string value if self is a MetaItem and the MetaItem is a
 144     /// MetaItemKind::NameValue variant containing a string, otherwise None.
 145     pub fn value_str(&self) -> Option<Symbol> {
 146         self.meta_item().and_then(|meta_item| meta_item.value_str())
 147     }
 148
 149     /// Returns a name and single literal value tuple of the MetaItem.
 150     pub fn name_value_literal(&self) -> Option<(Name, &Lit)> {
 151         self.meta_item().and_then(
 152             |meta_item| meta_item.meta_item_list().and_then(
 153                 |meta_item_list| {
 154                     if meta_item_list.len() == 1 {
 155                         let nested_item = &meta_item_list[0];
 156                         if nested_item.is_literal() {
 157                             Some((meta_item.name(), nested_item.literal().unwrap()))
 158                         } else {
 159                             None
 160                         }
 161                     }
 162                     else {
 163                         None
 164                     }}))
 165     }
 166
 167     /// Returns a MetaItem if self is a MetaItem with Kind Word.
 168     pub fn word(&self) -> Option<&MetaItem> {
 169         self.meta_item().and_then(|meta_item| if meta_item.is_word() {
 170             Some(meta_item)
 171         } else {
 172             None
 173         })
 174     }
 175
 176     /// Gets a list of inner meta items from a list MetaItem type.
 177     pub fn meta_item_list(&self) -> Option<&[NestedMetaItem]> {
 178         self.meta_item().and_then(|meta_item| meta_item.meta_item_list())
 179     }
 180
 181     /// Returns `true` if the variant is MetaItem.
 182     pub fn is_meta_item(&self) -> bool {
 183         self.meta_item().is_some()
 184     }
 185
 186     /// Returns `true` if the variant is Literal.
 187     pub fn is_literal(&self) -> bool {
 188         self.literal().is_some()
 189     }
 190
 191     /// Returns `true` if self is a MetaItem and the meta item is a word.
 192     pub fn is_word(&self) -> bool {
 193         self.word().is_some()
 194     }
 195
 196     /// Returns `true` if self is a MetaItem and the meta item is a ValueString.
 197     pub fn is_value_str(&self) -> bool {
 198         self.value_str().is_some()
 199     }
 200
 201     /// Returns `true` if self is a MetaItem and the meta item is a list.
 202     pub fn is_meta_item_list(&self) -> bool {
 203         self.meta_item_list().is_some()
 204     }
 205 }
 206
 207 impl Attribute {
 208     pub fn check_name(&self, name: &str) -> bool {
 209         let matches = self.path == name;
 210         if matches {
 211             mark_used(self);
 212         }
 213         matches
 214     }
 215
 216     pub fn name(&self) -> Option<Name> {
 217         match self.path.segments.len() {
 218             1 => Some(self.path.segments[0].identifier.name),
 219             _ => None,
 220         }
 221     }
 222
 223     pub fn value_str(&self) -> Option<Symbol> {
 224         self.meta().and_then(|meta| meta.value_str())
 225     }
 226
 227     pub fn meta_item_list(&self) -> Option<Vec<NestedMetaItem>> {
 228         match self.meta() {
 229             Some(MetaItem { node: MetaItemKind::List(list), .. }) => Some(list),
 230             _ => None
 231         }
 232     }
 233
 234     pub fn is_word(&self) -> bool {
 235         self.path.segments.len() == 1 && self.tokens.is_empty()
 236     }
 237
 238     pub fn span(&self) -> Span {
 239         self.span
 240     }
 241
 242     pub fn is_meta_item_list(&self) -> bool {
 243         self.meta_item_list().is_some()
 244     }
 245
 246     /// Indicates if the attribute is a Value String.
 247     pub fn is_value_str(&self) -> bool {
 248         self.value_str().is_some()
 249     }
 250 }
 251
 252 impl MetaItem {
 253     pub fn name(&self) -> Name {
 254         self.name
 255     }
 256
 257     pub fn value_str(&self) -> Option<Symbol> {
 258         match self.node {
 259             MetaItemKind::NameValue(ref v) => {
 260                 match v.node {
 261                     LitKind::Str(ref s, _) => Some(*s),
 262                     _ => None,
 263                 }
 264             },
 265             _ => None
 266         }
 267     }
 268
 269     pub fn meta_item_list(&self) -> Option<&[NestedMetaItem]> {
 270         match self.node {
 271             MetaItemKind::List(ref l) => Some(&l[..]),
 272             _ => None
 273         }
 274     }
 275
 276     pub fn is_word(&self) -> bool {
 277         match self.node {
 278             MetaItemKind::Word => true,
 279             _ => false,
 280         }
 281     }
 282
 283     pub fn span(&self) -> Span { self.span }
 284
 285     pub fn check_name(&self, name: &str) -> bool {
 286         self.name() == name
 287     }
 288
 289     pub fn is_value_str(&self) -> bool {
 290         self.value_str().is_some()
 291     }
 292
 293     pub fn is_meta_item_list(&self) -> bool {
 294         self.meta_item_list().is_some()
 295     }
 296 }
 297
 298 impl Attribute {
 299     /// Extract the MetaItem from inside this Attribute.
 300     pub fn meta(&self) -> Option<MetaItem> {
 301         let mut tokens = self.tokens.trees().peekable();
 302         Some(MetaItem {
 303             name: match self.path.segments.len() {
 304                 1 => self.path.segments[0].identifier.name,
 305                 _ => return None,
 306             },
 307             node: if let Some(node) = MetaItemKind::from_tokens(&mut tokens) {
 308                 if tokens.peek().is_some() {
 309                     return None;
 310                 }
 311                 node
 312             } else {
 313                 return None;
 314             },
 315             span: self.span,
 316         })
 317     }
 318
 319     pub fn parse<'a, T, F>(&self, sess: &'a ParseSess, mut f: F) -> PResult<'a, T>
 320         where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
 321     {
 322         let mut parser = Parser::new(sess, self.tokens.clone(), None, false, false);
 323         let result = f(&mut parser)?;
 324         if parser.token != token::Eof {
 325             parser.unexpected()?;
 326         }
 327         Ok(result)
 328     }
 329
 330     pub fn parse_list<'a, T, F>(&self, sess: &'a ParseSess, mut f: F) -> PResult<'a, Vec<T>>
 331         where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
 332     {
 333         if self.tokens.is_empty() {
 334             return Ok(Vec::new());
 335         }
 336         self.parse(sess, |parser| {
 337             parser.expect(&token::OpenDelim(token::Paren))?;
 338             let mut list = Vec::new();
 339             while !parser.eat(&token::CloseDelim(token::Paren)) {
 340                 list.push(f(parser)?);
 341                 if !parser.eat(&token::Comma) {
 342                    parser.expect(&token::CloseDelim(token::Paren))?;
 343                     break
 344                 }
 345             }
 346             Ok(list)
 347         })
 348     }
 349
 350     pub fn parse_meta<'a>(&self, sess: &'a ParseSess) -> PResult<'a, MetaItem> {
 351         if self.path.segments.len() > 1 {
 352             sess.span_diagnostic.span_err(self.path.span, "expected ident, found path");
 353         }
 354
 355         Ok(MetaItem {
 356             name: self.path.segments.last().unwrap().identifier.name,
 357             node: self.parse(sess, |parser| parser.parse_meta_item_kind())?,
 358             span: self.span,
 359         })
 360     }
 361
 362     /// Convert self to a normal #[doc="foo"] comment, if it is a
 363     /// comment like `///` or `/** */`. (Returns self unchanged for
 364     /// non-sugared doc attributes.)
 365     pub fn with_desugared_doc<T, F>(&self, f: F) -> T where
 366         F: FnOnce(&Attribute) -> T,
 367     {
 368         if self.is_sugared_doc {
 369             let comment = self.value_str().unwrap();
 370             let meta = mk_name_value_item_str(
 371                 Symbol::intern("doc"),
 372                 Symbol::intern(&strip_doc_comment_decoration(&comment.as_str())));
 373             let mut attr = if self.style == ast::AttrStyle::Outer {
 374                 mk_attr_outer(self.span, self.id, meta)
 375             } else {
 376                 mk_attr_inner(self.span, self.id, meta)
 377             };
 378             attr.is_sugared_doc = true;
 379             f(&attr)
 380         } else {
 381             f(self)
 382         }
 383     }
 384 }
 385
 386 /* Constructors */
 387
 388 pub fn mk_name_value_item_str(name: Name, value: Symbol) -> MetaItem {
 389     let value_lit = dummy_spanned(LitKind::Str(value, ast::StrStyle::Cooked));
 390     mk_spanned_name_value_item(DUMMY_SP, name, value_lit)
 391 }
 392
 393 pub fn mk_name_value_item(name: Name, value: ast::Lit) -> MetaItem {
 394     mk_spanned_name_value_item(DUMMY_SP, name, value)
 395 }
 396
 397 pub fn mk_list_item(name: Name, items: Vec<NestedMetaItem>) -> MetaItem {
 398     mk_spanned_list_item(DUMMY_SP, name, items)
 399 }
 400
 401 pub fn mk_list_word_item(name: Name) -> ast::NestedMetaItem {
 402     dummy_spanned(NestedMetaItemKind::MetaItem(mk_spanned_word_item(DUMMY_SP, name)))
 403 }
 404
 405 pub fn mk_word_item(name: Name) -> MetaItem {
 406     mk_spanned_word_item(DUMMY_SP, name)
 407 }
 408
 409 pub fn mk_spanned_name_value_item(sp: Span, name: Name, value: ast::Lit) -> MetaItem {
 410     MetaItem { span: sp, name: name, node: MetaItemKind::NameValue(value) }
 411 }
 412
 413 pub fn mk_spanned_list_item(sp: Span, name: Name, items: Vec<NestedMetaItem>) -> MetaItem {
 414     MetaItem { span: sp, name: name, node: MetaItemKind::List(items) }
 415 }
 416
 417 pub fn mk_spanned_word_item(sp: Span, name: Name) -> MetaItem {
 418     MetaItem { span: sp, name: name, node: MetaItemKind::Word }
 419 }
 420
 421 pub fn mk_attr_id() -> AttrId {
 422     use std::sync::atomic::AtomicUsize;
 423     use std::sync::atomic::Ordering;
 424
 425     static NEXT_ATTR_ID: AtomicUsize = AtomicUsize::new(0);
 426
 427     let id = NEXT_ATTR_ID.fetch_add(1, Ordering::SeqCst);
 428     assert!(id != ::std::usize::MAX);
 429     AttrId(id)
 430 }
 431
 432 /// Returns an inner attribute with the given value.
 433 pub fn mk_attr_inner(span: Span, id: AttrId, item: MetaItem) -> Attribute {
 434     mk_spanned_attr_inner(span, id, item)
 435 }
 436
 437 /// Returns an inner attribute with the given value and span.
 438 pub fn mk_spanned_attr_inner(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
 439     Attribute {
 440         id,
 441         style: ast::AttrStyle::Inner,
 442         path: ast::Path::from_ident(item.span, ast::Ident::with_empty_ctxt(item.name)),
 443         tokens: item.node.tokens(item.span),
 444         is_sugared_doc: false,
 445         span: sp,
 446     }
 447 }
 448
 449
 450 /// Returns an outer attribute with the given value.
 451 pub fn mk_attr_outer(span: Span, id: AttrId, item: MetaItem) -> Attribute {
 452     mk_spanned_attr_outer(span, id, item)
 453 }
 454
 455 /// Returns an outer attribute with the given value and span.
 456 pub fn mk_spanned_attr_outer(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
 457     Attribute {
 458         id,
 459         style: ast::AttrStyle::Outer,
 460         path: ast::Path::from_ident(item.span, ast::Ident::with_empty_ctxt(item.name)),
 461         tokens: item.node.tokens(item.span),
 462         is_sugared_doc: false,
 463         span: sp,
 464     }
 465 }
 466
 467 pub fn mk_sugared_doc_attr(id: AttrId, text: Symbol, span: Span) -> Attribute {
 468     let style = doc_comment_style(&text.as_str());
 469     let lit = respan(span, LitKind::Str(text, ast::StrStyle::Cooked));
 470     Attribute {
 471         id,
 472         style,
 473         path: ast::Path::from_ident(span, ast::Ident::from_str("doc")),
 474         tokens: MetaItemKind::NameValue(lit).tokens(span),
 475         is_sugared_doc: true,
 476         span,
 477     }
 478 }
 479
 480 pub fn list_contains_name(items: &[NestedMetaItem], name: &str) -> bool {
 481     items.iter().any(|item| {
 482         item.check_name(name)
 483     })
 484 }
 485
 486 pub fn contains_name(attrs: &[Attribute], name: &str) -> bool {
 487     attrs.iter().any(|item| {
 488         item.check_name(name)
 489     })
 490 }
 491
 492 pub fn find_by_name<'a>(attrs: &'a [Attribute], name: &str) -> Option<&'a Attribute> {
 493     attrs.iter().find(|attr| attr.check_name(name))
 494 }
 495
 496 pub fn first_attr_value_str_by_name(attrs: &[Attribute], name: &str) -> Option<Symbol> {
 497     attrs.iter()
 498         .find(|at| at.check_name(name))
 499         .and_then(|at| at.value_str())
 500 }
 501
 502 /// Check if `attrs` contains an attribute like `#![feature(feature_name)]`.
 503 /// This will not perform any "sanity checks" on the form of the attributes.
 504 pub fn contains_feature_attr(attrs: &[Attribute], feature_name: &str) -> bool {
 505     attrs.iter().any(|item| {
 506         item.check_name("feature") &&
 507         item.meta_item_list().map(|list| {
 508             list.iter().any(|mi| {
 509                 mi.word().map(|w| w.name() == feature_name)
 510                          .unwrap_or(false)
 511             })
 512         }).unwrap_or(false)
 513     })
 514 }
 515
 516 /* Higher-level applications */
 517
 518 pub fn find_crate_name(attrs: &[Attribute]) -> Option<Symbol> {
 519     first_attr_value_str_by_name(attrs, "crate_name")
 520 }
 521
 522 #[derive(Copy, Clone, Hash, PartialEq, RustcEncodable, RustcDecodable)]
 523 pub enum InlineAttr {
 524     None,
 525     Hint,
 526     Always,
 527     Never,
 528 }
 529
 530 #[derive(Copy, Clone, PartialEq)]
 531 pub enum UnwindAttr {
 532     Allowed,
 533     Aborts,
 534 }
 535
 536 /// Determine what `#[unwind]` attribute is present in `attrs`, if any.
 537 pub fn find_unwind_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> Option<UnwindAttr> {
 538     let syntax_error = |attr: &Attribute| {
 539         mark_used(attr);
 540         diagnostic.map(|d| {
 541             span_err!(d, attr.span, E0633, "malformed `#[unwind]` attribute");
 542         });
 543         None
 544     };
 545
 546     attrs.iter().fold(None, |ia, attr| {
 547         if attr.path != "unwind" {
 548             return ia;
 549         }
 550         let meta = match attr.meta() {
 551             Some(meta) => meta.node,
 552             None => return ia,
 553         };
 554         match meta {
 555             MetaItemKind::Word => {
 556                 syntax_error(attr)
 557             }
 558             MetaItemKind::List(ref items) => {
 559                 mark_used(attr);
 560                 if items.len() != 1 {
 561                     syntax_error(attr)
 562                 } else if list_contains_name(&items[..], "allowed") {
 563                     Some(UnwindAttr::Allowed)
 564                 } else if list_contains_name(&items[..], "aborts") {
 565                     Some(UnwindAttr::Aborts)
 566                 } else {
 567                     syntax_error(attr)
 568                 }
 569             }
 570             _ => ia,
 571         }
 572     })
 573 }
 574
 575
 576 /// Tests if a cfg-pattern matches the cfg set
 577 pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Features>) -> bool {
 578     eval_condition(cfg, sess, &mut |cfg| {
 579         if let (Some(feats), Some(gated_cfg)) = (features, GatedCfg::gate(cfg)) {
 580             gated_cfg.check_and_emit(sess, feats);
 581         }
 582         sess.config.contains(&(cfg.name(), cfg.value_str()))
 583     })
 584 }
 585
 586 /// Evaluate a cfg-like condition (with `any` and `all`), using `eval` to
 587 /// evaluate individual items.
 588 pub fn eval_condition<F>(cfg: &ast::MetaItem, sess: &ParseSess, eval: &mut F)
 589                          -> bool
 590     where F: FnMut(&ast::MetaItem) -> bool
 591 {
 592     match cfg.node {
 593         ast::MetaItemKind::List(ref mis) => {
 594             for mi in mis.iter() {
 595                 if !mi.is_meta_item() {
 596                     handle_errors(&sess.span_diagnostic, mi.span, AttrError::UnsupportedLiteral);
 597                     return false;
 598                 }
 599             }
 600
 601             // The unwraps below may look dangerous, but we've already asserted
 602             // that they won't fail with the loop above.
 603             match &*cfg.name.as_str() {
 604                 "any" => mis.iter().any(|mi| {
 605                     eval_condition(mi.meta_item().unwrap(), sess, eval)
 606                 }),
 607                 "all" => mis.iter().all(|mi| {
 608                     eval_condition(mi.meta_item().unwrap(), sess, eval)
 609                 }),
 610                 "not" => {
 611                     if mis.len() != 1 {
 612                         span_err!(sess.span_diagnostic, cfg.span, E0536, "expected 1 cfg-pattern");
 613                         return false;
 614                     }
 615
 616                     !eval_condition(mis[0].meta_item().unwrap(), sess, eval)
 617                 },
 618                 p => {
 619                     span_err!(sess.span_diagnostic, cfg.span, E0537, "invalid predicate `{}`", p);
 620                     false
 621                 }
 622             }
 623         },
 624         ast::MetaItemKind::Word | ast::MetaItemKind::NameValue(..) => {
 625             eval(cfg)
 626         }
 627     }
 628 }
 629
 630 /// Represents the #[stable], #[unstable], #[rustc_{deprecated,const_unstable}] attributes.
 631 #[derive(RustcEncodable, RustcDecodable, Clone, Debug, PartialEq, Eq, Hash)]
 632 pub struct Stability {
 633     pub level: StabilityLevel,
 634     pub feature: Symbol,
 635     pub rustc_depr: Option<RustcDeprecation>,
 636     pub rustc_const_unstable: Option<RustcConstUnstable>,
 637 }
 638
 639 /// The available stability levels.
 640 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 641 pub enum StabilityLevel {
 642     // Reason for the current stability level and the relevant rust-lang issue
 643     Unstable { reason: Option<Symbol>, issue: u32 },
 644     Stable { since: Symbol },
 645 }
 646
 647 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 648 pub struct RustcDeprecation {
 649     pub since: Symbol,
 650     pub reason: Symbol,
 651 }
 652
 653 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 654 pub struct RustcConstUnstable {
 655     pub feature: Symbol,
 656 }
 657
 658 #[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
 659 pub struct Deprecation {
 660     pub since: Option<Symbol>,
 661     pub note: Option<Symbol>,
 662 }
 663
 664 impl StabilityLevel {
 665     pub fn is_unstable(&self) -> bool { if let Unstable {..} = *self { true } else { false }}
 666     pub fn is_stable(&self) -> bool { if let Stable {..} = *self { true } else { false }}
 667 }
 668
 669 fn find_stability_generic<'a, I>(diagnostic: &Handler,
 670                                  attrs_iter: I,
 671                                  item_sp: Span)
 672                                  -> Option<Stability>
 673     where I: Iterator<Item = &'a Attribute>
 674 {
 675     let mut stab: Option<Stability> = None;
 676     let mut rustc_depr: Option<RustcDeprecation> = None;
 677     let mut rustc_const_unstable: Option<RustcConstUnstable> = None;
 678
 679     'outer: for attr in attrs_iter {
 680         if ![
 681             "rustc_deprecated",
 682             "rustc_const_unstable",
 683             "unstable",
 684             "stable",
 685         ].iter().any(|&s| attr.path == s) {
 686             continue // not a stability level
 687         }
 688
 689         mark_used(attr);
 690
 691         let meta = attr.meta();
 692         if let Some(MetaItem { node: MetaItemKind::List(ref metas), .. }) = meta {
 693             let meta = meta.as_ref().unwrap();
 694             let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
 695                 if item.is_some() {
 696                     handle_errors(diagnostic, meta.span, AttrError::MultipleItem(meta.name()));
 697                     return false
 698                 }
 699                 if let Some(v) = meta.value_str() {
 700                     *item = Some(v);
 701                     true
 702                 } else {
 703                     span_err!(diagnostic, meta.span, E0539, "incorrect meta item");
 704                     false
 705                 }
 706             };
 707
 708             macro_rules! get_meta {
 709                 ($($name:ident),+) => {
 710                     $(
 711                         let mut $name = None;
 712                     )+
 713                     for meta in metas {
 714                         if let Some(mi) = meta.meta_item() {
 715                             match &*mi.name().as_str() {
 716                                 $(
 717                                     stringify!($name)
 718                                         => if !get(mi, &mut $name) { continue 'outer },
 719                                 )+
 720                                 _ => {
 721                                     handle_errors(diagnostic, mi.span,
 722                                                   AttrError::UnknownMetaItem(mi.name()));
 723                                     continue 'outer
 724                                 }
 725                             }
 726                         } else {
 727                             handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
 728                             continue 'outer
 729                         }
 730                     }
 731                 }
 732             }
 733
 734             match &*meta.name.as_str() {
 735                 "rustc_deprecated" => {
 736                     if rustc_depr.is_some() {
 737                         span_err!(diagnostic, item_sp, E0540,
 738                                   "multiple rustc_deprecated attributes");
 739                         continue 'outer
 740                     }
 741
 742                     get_meta!(since, reason);
 743
 744                     match (since, reason) {
 745                         (Some(since), Some(reason)) => {
 746                             rustc_depr = Some(RustcDeprecation {
 747                                 since,
 748                                 reason,
 749                             })
 750                         }
 751                         (None, _) => {
 752                             handle_errors(diagnostic, attr.span(), AttrError::MissingSince);
 753                             continue
 754                         }
 755                         _ => {
 756                             span_err!(diagnostic, attr.span(), E0543, "missing 'reason'");
 757                             continue
 758                         }
 759                     }
 760                 }
 761                 "rustc_const_unstable" => {
 762                     if rustc_const_unstable.is_some() {
 763                         span_err!(diagnostic, item_sp, E0553,
 764                                   "multiple rustc_const_unstable attributes");
 765                         continue 'outer
 766                     }
 767
 768                     get_meta!(feature);
 769                     if let Some(feature) = feature {
 770                         rustc_const_unstable = Some(RustcConstUnstable {
 771                             feature
 772                         });
 773                     } else {
 774                         span_err!(diagnostic, attr.span(), E0629, "missing 'feature'");
 775                         continue
 776                     }
 777                 }
 778                 "unstable" => {
 779                     if stab.is_some() {
 780                         handle_errors(diagnostic, attr.span(), AttrError::MultipleStabilityLevels);
 781                         break
 782                     }
 783
 784                     let mut feature = None;
 785                     let mut reason = None;
 786                     let mut issue = None;
 787                     for meta in metas {
 788                         if let Some(mi) = meta.meta_item() {
 789                             match &*mi.name().as_str() {
 790                                 "feature" => if !get(mi, &mut feature) { continue 'outer },
 791                                 "reason" => if !get(mi, &mut reason) { continue 'outer },
 792                                 "issue" => if !get(mi, &mut issue) { continue 'outer },
 793                                 _ => {
 794                                     handle_errors(diagnostic, meta.span,
 795                                                   AttrError::UnknownMetaItem(mi.name()));
 796                                     continue 'outer
 797                                 }
 798                             }
 799                         } else {
 800                             handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
 801                             continue 'outer
 802                         }
 803                     }
 804
 805                     match (feature, reason, issue) {
 806                         (Some(feature), reason, Some(issue)) => {
 807                             stab = Some(Stability {
 808                                 level: Unstable {
 809                                     reason,
 810                                     issue: {
 811                                         if let Ok(issue) = issue.as_str().parse() {
 812                                             issue
 813                                         } else {
 814                                             span_err!(diagnostic, attr.span(), E0545,
 815                                                       "incorrect 'issue'");
 816                                             continue
 817                                         }
 818                                     }
 819                                 },
 820                                 feature,
 821                                 rustc_depr: None,
 822                                 rustc_const_unstable: None,
 823                             })
 824                         }
 825                         (None, _, _) => {
 826                             handle_errors(diagnostic, attr.span(), AttrError::MissingFeature);
 827                             continue
 828                         }
 829                         _ => {
 830                             span_err!(diagnostic, attr.span(), E0547, "missing 'issue'");
 831                             continue
 832                         }
 833                     }
 834                 }
 835                 "stable" => {
 836                     if stab.is_some() {
 837                         handle_errors(diagnostic, attr.span(), AttrError::MultipleStabilityLevels);
 838                         break
 839                     }
 840
 841                     let mut feature = None;
 842                     let mut since = None;
 843                     for meta in metas {
 844                         if let NestedMetaItemKind::MetaItem(ref mi) = meta.node {
 845                             match &*mi.name().as_str() {
 846                                 "feature" => if !get(mi, &mut feature) { continue 'outer },
 847                                 "since" => if !get(mi, &mut since) { continue 'outer },
 848                                 _ => {
 849                                     handle_errors(diagnostic, meta.span,
 850                                                   AttrError::UnknownMetaItem(mi.name()));
 851                                     continue 'outer
 852                                 }
 853                             }
 854                         } else {
 855                             handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
 856                             continue 'outer
 857                         }
 858                     }
 859
 860                     match (feature, since) {
 861                         (Some(feature), Some(since)) => {
 862                             stab = Some(Stability {
 863                                 level: Stable {
 864                                     since,
 865                                 },
 866                                 feature,
 867                                 rustc_depr: None,
 868                                 rustc_const_unstable: None,
 869                             })
 870                         }
 871                         (None, _) => {
 872                             handle_errors(diagnostic, attr.span(), AttrError::MissingFeature);
 873                             continue
 874                         }
 875                         _ => {
 876                             handle_errors(diagnostic, attr.span(), AttrError::MissingSince);
 877                             continue
 878                         }
 879                     }
 880                 }
 881                 _ => unreachable!()
 882             }
 883         } else {
 884             span_err!(diagnostic, attr.span(), E0548, "incorrect stability attribute type");
 885             continue
 886         }
 887     }
 888
 889     // Merge the deprecation info into the stability info
 890     if let Some(rustc_depr) = rustc_depr {
 891         if let Some(ref mut stab) = stab {
 892             stab.rustc_depr = Some(rustc_depr);
 893         } else {
 894             span_err!(diagnostic, item_sp, E0549,
 895                       "rustc_deprecated attribute must be paired with \
 896                        either stable or unstable attribute");
 897         }
 898     }
 899
 900     // Merge the const-unstable info into the stability info
 901     if let Some(rustc_const_unstable) = rustc_const_unstable {
 902         if let Some(ref mut stab) = stab {
 903             stab.rustc_const_unstable = Some(rustc_const_unstable);
 904         } else {
 905             span_err!(diagnostic, item_sp, E0630,
 906                       "rustc_const_unstable attribute must be paired with \
 907                        either stable or unstable attribute");
 908         }
 909     }
 910
 911     stab
 912 }
 913
 914 fn find_deprecation_generic<'a, I>(diagnostic: &Handler,
 915                                    attrs_iter: I,
 916                                    item_sp: Span)
 917                                    -> Option<Deprecation>
 918     where I: Iterator<Item = &'a Attribute>
 919 {
 920     let mut depr: Option<Deprecation> = None;
 921
 922     'outer: for attr in attrs_iter {
 923         if attr.path != "deprecated" {
 924             continue
 925         }
 926
 927         mark_used(attr);
 928
 929         if depr.is_some() {
 930             span_err!(diagnostic, item_sp, E0550, "multiple deprecated attributes");
 931             break
 932         }
 933
 934         depr = if let Some(metas) = attr.meta_item_list() {
 935             let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
 936                 if item.is_some() {
 937                     handle_errors(diagnostic, meta.span, AttrError::MultipleItem(meta.name()));
 938                     return false
 939                 }
 940                 if let Some(v) = meta.value_str() {
 941                     *item = Some(v);
 942                     true
 943                 } else {
 944                     span_err!(diagnostic, meta.span, E0551, "incorrect meta item");
 945                     false
 946                 }
 947             };
 948
 949             let mut since = None;
 950             let mut note = None;
 951             for meta in metas {
 952                 if let NestedMetaItemKind::MetaItem(ref mi) = meta.node {
 953                     match &*mi.name().as_str() {
 954                         "since" => if !get(mi, &mut since) { continue 'outer },
 955                         "note" => if !get(mi, &mut note) { continue 'outer },
 956                         _ => {
 957                             handle_errors(diagnostic, meta.span,
 958                                           AttrError::UnknownMetaItem(mi.name()));
 959                             continue 'outer
 960                         }
 961                     }
 962                 } else {
 963                     handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
 964                     continue 'outer
 965                 }
 966             }
 967
 968             Some(Deprecation {since: since, note: note})
 969         } else {
 970             Some(Deprecation{since: None, note: None})
 971         }
 972     }
 973
 974     depr
 975 }
 976
 977 /// Find the first stability attribute. `None` if none exists.
 978 pub fn find_stability(diagnostic: &Handler, attrs: &[Attribute],
 979                       item_sp: Span) -> Option<Stability> {
 980     find_stability_generic(diagnostic, attrs.iter(), item_sp)
 981 }
 982
 983 /// Find the deprecation attribute. `None` if none exists.
 984 pub fn find_deprecation(diagnostic: &Handler, attrs: &[Attribute],
 985                         item_sp: Span) -> Option<Deprecation> {
 986     find_deprecation_generic(diagnostic, attrs.iter(), item_sp)
 987 }
 988
 989
 990 /// Parse #[repr(...)] forms.
 991 ///
 992 /// Valid repr contents: any of the primitive integral type names (see
 993 /// `int_type_of_word`, below) to specify enum discriminant type; `C`, to use
 994 /// the same discriminant size that the corresponding C enum would or C
 995 /// structure layout, `packed` to remove padding, and `transparent` to elegate representation
 996 /// concerns to the only non-ZST field.
 997 pub fn find_repr_attrs(diagnostic: &Handler, attr: &Attribute) -> Vec<ReprAttr> {
 998     let mut acc = Vec::new();
 999     if attr.path == "repr" {
1000         if let Some(items) = attr.meta_item_list() {
1001             mark_used(attr);
1002             for item in items {
1003                 if !item.is_meta_item() {
1004                     handle_errors(diagnostic, item.span, AttrError::UnsupportedLiteral);
1005                     continue
1006                 }
1007
1008                 let mut recognised = false;
1009                 if let Some(mi) = item.word() {
1010                     let word = &*mi.name().as_str();
1011                     let hint = match word {
1012                         "C" => Some(ReprC),
1013                         "packed" => Some(ReprPacked),
1014                         "simd" => Some(ReprSimd),
1015                         "transparent" => Some(ReprTransparent),
1016                         _ => match int_type_of_word(word) {
1017                             Some(ity) => Some(ReprInt(ity)),
1018                             None => {
1019                                 None
1020                             }
1021                         }
1022                     };
1023
1024                     if let Some(h) = hint {
1025                         recognised = true;
1026                         acc.push(h);
1027                     }
1028                 } else if let Some((name, value)) = item.name_value_literal() {
1029                     if name == "align" {
1030                         recognised = true;
1031                         let mut align_error = None;
1032                         if let ast::LitKind::Int(align, ast::LitIntType::Unsuffixed) = value.node {
1033                             if align.is_power_of_two() {
1034                                 // rustc::ty::layout::Align restricts align to <= 2147483647
1035                                 if align <= 2147483647 {
1036                                     acc.push(ReprAlign(align as u32));
1037                                 } else {
1038                                     align_error = Some("larger than 2147483647");
1039                                 }
1040                             } else {
1041                                 align_error = Some("not a power of two");
1042                             }
1043                         } else {
1044                             align_error = Some("not an unsuffixed integer");
1045                         }
1046                         if let Some(align_error) = align_error {
1047                             span_err!(diagnostic, item.span, E0589,
1048                                       "invalid `repr(align)` attribute: {}", align_error);
1049                         }
1050                     }
1051                 }
1052                 if !recognised {
1053                     // Not a word we recognize
1054                     span_err!(diagnostic, item.span, E0552,
1055                               "unrecognized representation hint");
1056                 }
1057             }
1058         }
1059     }
1060     acc
1061 }
1062
1063 fn int_type_of_word(s: &str) -> Option<IntType> {
1064     match s {
1065         "i8" => Some(SignedInt(ast::IntTy::I8)),
1066         "u8" => Some(UnsignedInt(ast::UintTy::U8)),
1067         "i16" => Some(SignedInt(ast::IntTy::I16)),
1068         "u16" => Some(UnsignedInt(ast::UintTy::U16)),
1069         "i32" => Some(SignedInt(ast::IntTy::I32)),
1070         "u32" => Some(UnsignedInt(ast::UintTy::U32)),
1071         "i64" => Some(SignedInt(ast::IntTy::I64)),
1072         "u64" => Some(UnsignedInt(ast::UintTy::U64)),
1073         "i128" => Some(SignedInt(ast::IntTy::I128)),
1074         "u128" => Some(UnsignedInt(ast::UintTy::U128)),
1075         "isize" => Some(SignedInt(ast::IntTy::Isize)),
1076         "usize" => Some(UnsignedInt(ast::UintTy::Usize)),
1077         _ => None
1078     }
1079 }
1080
1081 #[derive(PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
1082 pub enum ReprAttr {
1083     ReprInt(IntType),
1084     ReprC,
1085     ReprPacked,
1086     ReprSimd,
1087     ReprTransparent,
1088     ReprAlign(u32),
1089 }
1090
1091 #[derive(Eq, Hash, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
1092 pub enum IntType {
1093     SignedInt(ast::IntTy),
1094     UnsignedInt(ast::UintTy)
1095 }
1096
1097 impl IntType {
1098     #[inline]
1099     pub fn is_signed(self) -> bool {
1100         match self {
1101             SignedInt(..) => true,
1102             UnsignedInt(..) => false
1103         }
1104     }
1105 }
1106
1107 impl MetaItem {
1108     fn tokens(&self) -> TokenStream {
1109         let ident = TokenTree::Token(self.span,
1110                                      Token::from_ast_ident(Ident::with_empty_ctxt(self.name)));
1111         TokenStream::concat(vec![ident.into(), self.node.tokens(self.span)])
1112     }
1113
1114     fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<MetaItem>
1115         where I: Iterator<Item = TokenTree>,
1116     {
1117         let (span, name) = match tokens.next() {
1118             Some(TokenTree::Token(span, Token::Ident(ident, _))) => (span, ident.name),
1119             Some(TokenTree::Token(_, Token::Interpolated(ref nt))) => match nt.0 {
1120                 token::Nonterminal::NtIdent(ident, _) => (ident.span, ident.node.name),
1121                 token::Nonterminal::NtMeta(ref meta) => return Some(meta.clone()),
1122                 _ => return None,
1123             },
1124             _ => return None,
1125         };
1126         let list_closing_paren_pos = tokens.peek().map(|tt| tt.span().hi());
1127         let node = MetaItemKind::from_tokens(tokens)?;
1128         let hi = match node {
1129             MetaItemKind::NameValue(ref lit) => lit.span.hi(),
1130             MetaItemKind::List(..) => list_closing_paren_pos.unwrap_or(span.hi()),
1131             _ => span.hi(),
1132         };
1133         Some(MetaItem { name, node, span: span.with_hi(hi) })
1134     }
1135 }
1136
1137 impl MetaItemKind {
1138     pub fn tokens(&self, span: Span) -> TokenStream {
1139         match *self {
1140             MetaItemKind::Word => TokenStream::empty(),
1141             MetaItemKind::NameValue(ref lit) => {
1142                 TokenStream::concat(vec![TokenTree::Token(span, Token::Eq).into(), lit.tokens()])
1143             }
1144             MetaItemKind::List(ref list) => {
1145                 let mut tokens = Vec::new();
1146                 for (i, item) in list.iter().enumerate() {
1147                     if i > 0 {
1148                         tokens.push(TokenTree::Token(span, Token::Comma).into());
1149                     }
1150                     tokens.push(item.node.tokens());
1151                 }
1152                 TokenTree::Delimited(span, Delimited {
1153                     delim: token::Paren,
1154                     tts: TokenStream::concat(tokens).into(),
1155                 }).into()
1156             }
1157         }
1158     }
1159
1160     fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<MetaItemKind>
1161         where I: Iterator<Item = TokenTree>,
1162     {
1163         let delimited = match tokens.peek().cloned() {
1164             Some(TokenTree::Token(_, token::Eq)) => {
1165                 tokens.next();
1166                 return if let Some(TokenTree::Token(span, token)) = tokens.next() {
1167                     LitKind::from_token(token)
1168                         .map(|lit| MetaItemKind::NameValue(Spanned { node: lit, span: span }))
1169                 } else {
1170                     None
1171                 };
1172             }
1173             Some(TokenTree::Delimited(_, ref delimited)) if delimited.delim == token::Paren => {
1174                 tokens.next();
1175                 delimited.stream()
1176             }
1177             _ => return Some(MetaItemKind::Word),
1178         };
1179
1180         let mut tokens = delimited.into_trees().peekable();
1181         let mut result = Vec::new();
1182         while let Some(..) = tokens.peek() {
1183             let item = NestedMetaItemKind::from_tokens(&mut tokens)?;
1184             result.push(respan(item.span(), item));
1185             match tokens.next() {
1186                 None | Some(TokenTree::Token(_, Token::Comma)) => {}
1187                 _ => return None,
1188             }
1189         }
1190         Some(MetaItemKind::List(result))
1191     }
1192 }
1193
1194 impl NestedMetaItemKind {
1195     fn span(&self) -> Span {
1196         match *self {
1197             NestedMetaItemKind::MetaItem(ref item) => item.span,
1198             NestedMetaItemKind::Literal(ref lit) => lit.span,
1199         }
1200     }
1201
1202     fn tokens(&self) -> TokenStream {
1203         match *self {
1204             NestedMetaItemKind::MetaItem(ref item) => item.tokens(),
1205             NestedMetaItemKind::Literal(ref lit) => lit.tokens(),
1206         }
1207     }
1208
1209     fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<NestedMetaItemKind>
1210         where I: Iterator<Item = TokenTree>,
1211     {
1212         if let Some(TokenTree::Token(span, token)) = tokens.peek().cloned() {
1213             if let Some(node) = LitKind::from_token(token) {
1214                 tokens.next();
1215                 return Some(NestedMetaItemKind::Literal(respan(span, node)));
1216             }
1217         }
1218
1219         MetaItem::from_tokens(tokens).map(NestedMetaItemKind::MetaItem)
1220     }
1221 }
1222
1223 impl Lit {
1224     fn tokens(&self) -> TokenStream {
1225         TokenTree::Token(self.span, self.node.token()).into()
1226     }
1227 }
1228
1229 impl LitKind {
1230     fn token(&self) -> Token {
1231         use std::ascii;
1232
1233         match *self {
1234             LitKind::Str(string, ast::StrStyle::Cooked) => {
1235                 let mut escaped = String::new();
1236                 for ch in string.as_str().chars() {
1237                     escaped.extend(ch.escape_unicode());
1238                 }
1239                 Token::Literal(token::Lit::Str_(Symbol::intern(&escaped)), None)
1240             }
1241             LitKind::Str(string, ast::StrStyle::Raw(n)) => {
1242                 Token::Literal(token::Lit::StrRaw(string, n), None)
1243             }
1244             LitKind::ByteStr(ref bytes) => {
1245                 let string = bytes.iter().cloned().flat_map(ascii::escape_default)
1246                     .map(Into::<char>::into).collect::<String>();
1247                 Token::Literal(token::Lit::ByteStr(Symbol::intern(&string)), None)
1248             }
1249             LitKind::Byte(byte) => {
1250                 let string: String = ascii::escape_default(byte).map(Into::<char>::into).collect();
1251                 Token::Literal(token::Lit::Byte(Symbol::intern(&string)), None)
1252             }
1253             LitKind::Char(ch) => {
1254                 let string: String = ch.escape_default().map(Into::<char>::into).collect();
1255                 Token::Literal(token::Lit::Char(Symbol::intern(&string)), None)
1256             }
1257             LitKind::Int(n, ty) => {
1258                 let suffix = match ty {
1259                     ast::LitIntType::Unsigned(ty) => Some(Symbol::intern(ty.ty_to_string())),
1260                     ast::LitIntType::Signed(ty) => Some(Symbol::intern(ty.ty_to_string())),
1261                     ast::LitIntType::Unsuffixed => None,
1262                 };
1263                 Token::Literal(token::Lit::Integer(Symbol::intern(&n.to_string())), suffix)
1264             }
1265             LitKind::Float(symbol, ty) => {
1266                 Token::Literal(token::Lit::Float(symbol), Some(Symbol::intern(ty.ty_to_string())))
1267             }
1268             LitKind::FloatUnsuffixed(symbol) => Token::Literal(token::Lit::Float(symbol), None),
1269             LitKind::Bool(value) => Token::Ident(Ident::with_empty_ctxt(Symbol::intern(if value {
1270                 "true"
1271             } else {
1272                 "false"
1273             })), false),
1274         }
1275     }
1276
1277     fn from_token(token: Token) -> Option<LitKind> {
1278         match token {
1279             Token::Ident(ident, false) if ident.name == "true" => Some(LitKind::Bool(true)),
1280             Token::Ident(ident, false) if ident.name == "false" => Some(LitKind::Bool(false)),
1281             Token::Interpolated(ref nt) => match nt.0 {
1282                 token::NtExpr(ref v) => match v.node {
1283                     ExprKind::Lit(ref lit) => Some(lit.node.clone()),
1284                     _ => None,
1285                 },
1286                 _ => None,
1287             },
1288             Token::Literal(lit, suf) => {
1289                 let (suffix_illegal, result) = parse::lit_token(lit, suf, None);
1290                 if suffix_illegal && suf.is_some() {
1291                     return None;
1292                 }
1293                 result
1294             }
1295             _ => None,
1296         }
1297     }
1298 }
1299
1300 pub trait HasAttrs: Sized {
1301     fn attrs(&self) -> &[ast::Attribute];
1302     fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self;
1303 }
1304
1305 impl<T: HasAttrs> HasAttrs for Spanned<T> {
1306     fn attrs(&self) -> &[ast::Attribute] { self.node.attrs() }
1307     fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self {
1308         respan(self.span, self.node.map_attrs(f))
1309     }
1310 }
1311
1312 impl HasAttrs for Vec<Attribute> {
1313     fn attrs(&self) -> &[Attribute] {
1314         self
1315     }
1316     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
1317         f(self)
1318     }
1319 }
1320
1321 impl HasAttrs for ThinVec<Attribute> {
1322     fn attrs(&self) -> &[Attribute] {
1323         self
1324     }
1325     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
1326         f(self.into()).into()
1327     }
1328 }
1329
1330 impl<T: HasAttrs + 'static> HasAttrs for P<T> {
1331     fn attrs(&self) -> &[Attribute] {
1332         (**self).attrs()
1333     }
1334     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
1335         self.map(|t| t.map_attrs(f))
1336     }
1337 }
1338
1339 impl HasAttrs for StmtKind {
1340     fn attrs(&self) -> &[Attribute] {
1341         match *self {
1342             StmtKind::Local(ref local) => local.attrs(),
1343             StmtKind::Item(..) => &[],
1344             StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => expr.attrs(),
1345             StmtKind::Mac(ref mac) => {
1346                 let (_, _, ref attrs) = **mac;
1347                 attrs.attrs()
1348             }
1349         }
1350     }
1351
1352     fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
1353         match self {
1354             StmtKind::Local(local) => StmtKind::Local(local.map_attrs(f)),
1355             StmtKind::Item(..) => self,
1356             StmtKind::Expr(expr) => StmtKind::Expr(expr.map_attrs(f)),
1357             StmtKind::Semi(expr) => StmtKind::Semi(expr.map_attrs(f)),
1358             StmtKind::Mac(mac) => StmtKind::Mac(mac.map(|(mac, style, attrs)| {
1359                 (mac, style, attrs.map_attrs(f))
1360             })),
1361         }
1362     }
1363 }
1364
1365 impl HasAttrs for Stmt {
1366     fn attrs(&self) -> &[ast::Attribute] { self.node.attrs() }
1367     fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self {
1368         Stmt { id: self.id, node: self.node.map_attrs(f), span: self.span }
1369     }
1370 }
1371
1372 macro_rules! derive_has_attrs {
1373     ($($ty:path),*) => { $(
1374         impl HasAttrs for $ty {
1375             fn attrs(&self) -> &[Attribute] {
1376                 &self.attrs
1377             }
1378
1379             fn map_attrs<F>(mut self, f: F) -> Self
1380                 where F: FnOnce(Vec<Attribute>) -> Vec<Attribute>,
1381             {
1382                 self.attrs = self.attrs.map_attrs(f);
1383                 self
1384             }
1385         }
1386     )* }
1387 }
1388
1389 derive_has_attrs! {
1390     Item, Expr, Local, ast::ForeignItem, ast::StructField, ast::ImplItem, ast::TraitItem, ast::Arm,
1391     ast::Field, ast::FieldPat, ast::Variant_
1392 }