src/librustc_metadata/encoder.rs

   1 use crate::index::Index;
   2 use crate::schema::*;
   3
   4 use rustc::middle::cstore::{LinkagePreference, NativeLibrary,
   5                             EncodedMetadata, ForeignModule};
   6 use rustc::hir::def::CtorKind;
   7 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefIndex, DefId, LocalDefId, LOCAL_CRATE};
   8 use rustc::hir::GenericParamKind;
   9 use rustc::hir::map::definitions::DefPathTable;
  10 use rustc_data_structures::fingerprint::Fingerprint;
  11 use rustc::middle::dependency_format::Linkage;
  12 use rustc::middle::exported_symbols::{ExportedSymbol, SymbolExportLevel,
  13                                       metadata_symbol_name};
  14 use rustc::middle::lang_items;
  15 use rustc::mir::{self, interpret};
  16 use rustc::traits::specialization_graph;
  17 use rustc::ty::{self, Ty, TyCtxt, ReprOptions, SymbolName};
  18 use rustc::ty::codec::{self as ty_codec, TyEncoder};
  19 use rustc::ty::layout::VariantIdx;
  20
  21 use rustc::session::config::{self, CrateType};
  22 use rustc::util::nodemap::FxHashMap;
  23
  24 use rustc_data_structures::stable_hasher::StableHasher;
  25 use rustc_serialize::{Encodable, Encoder, SpecializedEncoder, opaque};
  26
  27 use std::hash::Hash;
  28 use std::path::Path;
  29 use rustc_data_structures::sync::Lrc;
  30 use std::u32;
  31 use syntax::ast;
  32 use syntax::attr;
  33 use syntax::source_map::Spanned;
  34 use syntax::symbol::{kw, sym, Ident};
  35 use syntax_pos::{self, FileName, SourceFile, Span};
  36 use log::{debug, trace};
  37
  38 use rustc::hir::{self, PatKind};
  39 use rustc::hir::itemlikevisit::ItemLikeVisitor;
  40 use rustc::hir::intravisit::{Visitor, NestedVisitorMap};
  41 use rustc::hir::intravisit;
  42
  43 pub struct EncodeContext<'tcx> {
  44     opaque: opaque::Encoder,
  45     pub tcx: TyCtxt<'tcx>,
  46
  47     entries_index: Index<'tcx>,
  48
  49     lazy_state: LazyState,
  50     type_shorthands: FxHashMap<Ty<'tcx>, usize>,
  51     predicate_shorthands: FxHashMap<ty::Predicate<'tcx>, usize>,
  52
  53     interpret_allocs: FxHashMap<interpret::AllocId, usize>,
  54     interpret_allocs_inverse: Vec<interpret::AllocId>,
  55
  56     // This is used to speed up Span encoding.
  57     source_file_cache: Lrc<SourceFile>,
  58 }
  59
  60 macro_rules! encoder_methods {
  61     ($($name:ident($ty:ty);)*) => {
  62         $(fn $name(&mut self, value: $ty) -> Result<(), Self::Error> {
  63             self.opaque.$name(value)
  64         })*
  65     }
  66 }
  67
  68 impl<'tcx> Encoder for EncodeContext<'tcx> {
  69     type Error = <opaque::Encoder as Encoder>::Error;
  70
  71     fn emit_unit(&mut self) -> Result<(), Self::Error> {
  72         Ok(())
  73     }
  74
  75     encoder_methods! {
  76         emit_usize(usize);
  77         emit_u128(u128);
  78         emit_u64(u64);
  79         emit_u32(u32);
  80         emit_u16(u16);
  81         emit_u8(u8);
  82
  83         emit_isize(isize);
  84         emit_i128(i128);
  85         emit_i64(i64);
  86         emit_i32(i32);
  87         emit_i16(i16);
  88         emit_i8(i8);
  89
  90         emit_bool(bool);
  91         emit_f64(f64);
  92         emit_f32(f32);
  93         emit_char(char);
  94         emit_str(&str);
  95     }
  96 }
  97
  98 impl<'tcx, T> SpecializedEncoder<Lazy<T>> for EncodeContext<'tcx> {
  99     fn specialized_encode(&mut self, lazy: &Lazy<T>) -> Result<(), Self::Error> {
 100         self.emit_lazy_distance(lazy.position, Lazy::<T>::min_size())
 101     }
 102 }
 103
 104 impl<'tcx, T> SpecializedEncoder<LazySeq<T>> for EncodeContext<'tcx> {
 105     fn specialized_encode(&mut self, seq: &LazySeq<T>) -> Result<(), Self::Error> {
 106         self.emit_usize(seq.len)?;
 107         if seq.len == 0 {
 108             return Ok(());
 109         }
 110         self.emit_lazy_distance(seq.position, LazySeq::<T>::min_size(seq.len))
 111     }
 112 }
 113
 114 impl<'tcx> SpecializedEncoder<CrateNum> for EncodeContext<'tcx> {
 115     #[inline]
 116     fn specialized_encode(&mut self, cnum: &CrateNum) -> Result<(), Self::Error> {
 117         self.emit_u32(cnum.as_u32())
 118     }
 119 }
 120
 121 impl<'tcx> SpecializedEncoder<DefId> for EncodeContext<'tcx> {
 122     #[inline]
 123     fn specialized_encode(&mut self, def_id: &DefId) -> Result<(), Self::Error> {
 124         let DefId {
 125             krate,
 126             index,
 127         } = *def_id;
 128
 129         krate.encode(self)?;
 130         index.encode(self)
 131     }
 132 }
 133
 134 impl<'tcx> SpecializedEncoder<DefIndex> for EncodeContext<'tcx> {
 135     #[inline]
 136     fn specialized_encode(&mut self, def_index: &DefIndex) -> Result<(), Self::Error> {
 137         self.emit_u32(def_index.as_u32())
 138     }
 139 }
 140
 141 impl<'tcx> SpecializedEncoder<Span> for EncodeContext<'tcx> {
 142     fn specialized_encode(&mut self, span: &Span) -> Result<(), Self::Error> {
 143         if span.is_dummy() {
 144             return TAG_INVALID_SPAN.encode(self)
 145         }
 146
 147         let span = span.data();
 148
 149         // The Span infrastructure should make sure that this invariant holds:
 150         debug_assert!(span.lo <= span.hi);
 151
 152         if !self.source_file_cache.contains(span.lo) {
 153             let source_map = self.tcx.sess.source_map();
 154             let source_file_index = source_map.lookup_source_file_idx(span.lo);
 155             self.source_file_cache = source_map.files()[source_file_index].clone();
 156         }
 157
 158         if !self.source_file_cache.contains(span.hi) {
 159             // Unfortunately, macro expansion still sometimes generates Spans
 160             // that malformed in this way.
 161             return TAG_INVALID_SPAN.encode(self)
 162         }
 163
 164         TAG_VALID_SPAN.encode(self)?;
 165         span.lo.encode(self)?;
 166
 167         // Encode length which is usually less than span.hi and profits more
 168         // from the variable-length integer encoding that we use.
 169         let len = span.hi - span.lo;
 170         len.encode(self)
 171
 172         // Don't encode the expansion context.
 173     }
 174 }
 175
 176 impl SpecializedEncoder<Ident> for EncodeContext<'tcx> {
 177     fn specialized_encode(&mut self, ident: &Ident) -> Result<(), Self::Error> {
 178         // FIXME(jseyfried): intercrate hygiene
 179         ident.name.encode(self)
 180     }
 181 }
 182
 183 impl<'tcx> SpecializedEncoder<LocalDefId> for EncodeContext<'tcx> {
 184     #[inline]
 185     fn specialized_encode(&mut self, def_id: &LocalDefId) -> Result<(), Self::Error> {
 186         self.specialized_encode(&def_id.to_def_id())
 187     }
 188 }
 189
 190 impl<'tcx> SpecializedEncoder<Ty<'tcx>> for EncodeContext<'tcx> {
 191     fn specialized_encode(&mut self, ty: &Ty<'tcx>) -> Result<(), Self::Error> {
 192         ty_codec::encode_with_shorthand(self, ty, |ecx| &mut ecx.type_shorthands)
 193     }
 194 }
 195
 196 impl<'tcx> SpecializedEncoder<interpret::AllocId> for EncodeContext<'tcx> {
 197     fn specialized_encode(&mut self, alloc_id: &interpret::AllocId) -> Result<(), Self::Error> {
 198         use std::collections::hash_map::Entry;
 199         let index = match self.interpret_allocs.entry(*alloc_id) {
 200             Entry::Occupied(e) => *e.get(),
 201             Entry::Vacant(e) => {
 202                 let idx = self.interpret_allocs_inverse.len();
 203                 self.interpret_allocs_inverse.push(*alloc_id);
 204                 e.insert(idx);
 205                 idx
 206             },
 207         };
 208
 209         index.encode(self)
 210     }
 211 }
 212
 213 impl<'tcx> SpecializedEncoder<ty::GenericPredicates<'tcx>> for EncodeContext<'tcx> {
 214     fn specialized_encode(&mut self,
 215                           predicates: &ty::GenericPredicates<'tcx>)
 216                           -> Result<(), Self::Error> {
 217         ty_codec::encode_predicates(self, predicates, |ecx| &mut ecx.predicate_shorthands)
 218     }
 219 }
 220
 221 impl<'tcx> SpecializedEncoder<Fingerprint> for EncodeContext<'tcx> {
 222     fn specialized_encode(&mut self, f: &Fingerprint) -> Result<(), Self::Error> {
 223         f.encode_opaque(&mut self.opaque)
 224     }
 225 }
 226
 227 impl<'tcx, T: Encodable> SpecializedEncoder<mir::ClearCrossCrate<T>> for EncodeContext<'tcx> {
 228     fn specialized_encode(&mut self,
 229                           _: &mir::ClearCrossCrate<T>)
 230                           -> Result<(), Self::Error> {
 231         Ok(())
 232     }
 233 }
 234
 235 impl<'tcx> TyEncoder for EncodeContext<'tcx> {
 236     fn position(&self) -> usize {
 237         self.opaque.position()
 238     }
 239 }
 240
 241 impl<'tcx> EncodeContext<'tcx> {
 242     fn emit_node<F: FnOnce(&mut Self, usize) -> R, R>(&mut self, f: F) -> R {
 243         assert_eq!(self.lazy_state, LazyState::NoNode);
 244         let pos = self.position();
 245         self.lazy_state = LazyState::NodeStart(pos);
 246         let r = f(self, pos);
 247         self.lazy_state = LazyState::NoNode;
 248         r
 249     }
 250
 251     fn emit_lazy_distance(&mut self,
 252                           position: usize,
 253                           min_size: usize)
 254                           -> Result<(), <Self as Encoder>::Error> {
 255         let min_end = position + min_size;
 256         let distance = match self.lazy_state {
 257             LazyState::NoNode => bug!("emit_lazy_distance: outside of a metadata node"),
 258             LazyState::NodeStart(start) => {
 259                 assert!(min_end <= start);
 260                 start - min_end
 261             }
 262             LazyState::Previous(last_min_end) => {
 263                 assert!(
 264                     last_min_end <= position,
 265                     "make sure that the calls to `lazy*` \
 266                     are in the same order as the metadata fields",
 267                 );
 268                 position - last_min_end
 269             }
 270         };
 271         self.lazy_state = LazyState::Previous(min_end);
 272         self.emit_usize(distance)
 273     }
 274
 275     pub fn lazy<T: Encodable>(&mut self, value: &T) -> Lazy<T> {
 276         self.emit_node(|ecx, pos| {
 277             value.encode(ecx).unwrap();
 278
 279             assert!(pos + Lazy::<T>::min_size() <= ecx.position());
 280             Lazy::with_position(pos)
 281         })
 282     }
 283
 284     pub fn lazy_seq<I, T>(&mut self, iter: I) -> LazySeq<T>
 285         where I: IntoIterator<Item = T>,
 286               T: Encodable
 287     {
 288         self.emit_node(|ecx, pos| {
 289             let len = iter.into_iter().map(|value| value.encode(ecx).unwrap()).count();
 290
 291             assert!(pos + LazySeq::<T>::min_size(len) <= ecx.position());
 292             LazySeq::with_position_and_length(pos, len)
 293         })
 294     }
 295
 296     pub fn lazy_seq_ref<'b, I, T>(&mut self, iter: I) -> LazySeq<T>
 297         where I: IntoIterator<Item = &'b T>,
 298               T: 'b + Encodable
 299     {
 300         self.emit_node(|ecx, pos| {
 301             let len = iter.into_iter().map(|value| value.encode(ecx).unwrap()).count();
 302
 303             assert!(pos + LazySeq::<T>::min_size(len) <= ecx.position());
 304             LazySeq::with_position_and_length(pos, len)
 305         })
 306     }
 307
 308     /// Emit the data for a `DefId` to the metadata. The function to
 309     /// emit the data is `op`, and it will be given `data` as
 310     /// arguments. This `record` function will call `op` to generate
 311     /// the `Entry` (which may point to other encoded information)
 312     /// and will then record the `Lazy<Entry>` for use in the index.
 313     // FIXME(eddyb) remove this.
 314     pub fn record<DATA>(&mut self,
 315                         id: DefId,
 316                         op: impl FnOnce(&mut Self, DATA) -> Entry<'tcx>,
 317                         data: DATA)
 318     {
 319         assert!(id.is_local());
 320
 321         let entry = op(self, data);
 322         let entry = self.lazy(&entry);
 323         self.entries_index.record(id, entry);
 324     }
 325
 326     fn encode_info_for_items(&mut self) {
 327         let krate = self.tcx.hir().krate();
 328         let vis = Spanned { span: syntax_pos::DUMMY_SP, node: hir::VisibilityKind::Public };
 329         self.record(DefId::local(CRATE_DEF_INDEX),
 330                      EncodeContext::encode_info_for_mod,
 331                      (hir::CRATE_HIR_ID, &krate.module, &krate.attrs, &vis));
 332         krate.visit_all_item_likes(&mut self.as_deep_visitor());
 333         for macro_def in &krate.exported_macros {
 334             self.visit_macro_def(macro_def);
 335         }
 336     }
 337
 338     fn encode_def_path_table(&mut self) -> Lazy<DefPathTable> {
 339         let definitions = self.tcx.hir().definitions();
 340         self.lazy(definitions.def_path_table())
 341     }
 342
 343     fn encode_source_map(&mut self) -> LazySeq<syntax_pos::SourceFile> {
 344         let source_map = self.tcx.sess.source_map();
 345         let all_source_files = source_map.files();
 346
 347         let (working_dir, _cwd_remapped) = self.tcx.sess.working_dir.clone();
 348
 349         let adapted = all_source_files.iter()
 350             .filter(|source_file| {
 351                 // No need to re-export imported source_files, as any downstream
 352                 // crate will import them from their original source.
 353                 !source_file.is_imported()
 354             })
 355             .map(|source_file| {
 356                 match source_file.name {
 357                     // This path of this SourceFile has been modified by
 358                     // path-remapping, so we use it verbatim (and avoid
 359                     // cloning the whole map in the process).
 360                     _  if source_file.name_was_remapped => source_file.clone(),
 361
 362                     // Otherwise expand all paths to absolute paths because
 363                     // any relative paths are potentially relative to a
 364                     // wrong directory.
 365                     FileName::Real(ref name) => {
 366                         let mut adapted = (**source_file).clone();
 367                         adapted.name = Path::new(&working_dir).join(name).into();
 368                         adapted.name_hash = {
 369                             let mut hasher: StableHasher<u128> = StableHasher::new();
 370                             adapted.name.hash(&mut hasher);
 371                             hasher.finish()
 372                         };
 373                         Lrc::new(adapted)
 374                     },
 375
 376                     // expanded code, not from a file
 377                     _ => source_file.clone(),
 378                 }
 379             })
 380             .collect::<Vec<_>>();
 381
 382         self.lazy_seq_ref(adapted.iter().map(|rc| &**rc))
 383     }
 384
 385     fn encode_crate_root(&mut self) -> Lazy<CrateRoot<'tcx>> {
 386         let mut i = self.position();
 387
 388         let crate_deps = self.encode_crate_deps();
 389         let dylib_dependency_formats = self.encode_dylib_dependency_formats();
 390         let dep_bytes = self.position() - i;
 391
 392         // Encode the lib features.
 393         i = self.position();
 394         let lib_features = self.encode_lib_features();
 395         let lib_feature_bytes = self.position() - i;
 396
 397         // Encode the language items.
 398         i = self.position();
 399         let lang_items = self.encode_lang_items();
 400         let lang_items_missing = self.encode_lang_items_missing();
 401         let lang_item_bytes = self.position() - i;
 402
 403         // Encode the native libraries used
 404         i = self.position();
 405         let native_libraries = self.encode_native_libraries();
 406         let native_lib_bytes = self.position() - i;
 407
 408         let foreign_modules = self.encode_foreign_modules();
 409
 410         // Encode source_map
 411         i = self.position();
 412         let source_map = self.encode_source_map();
 413         let source_map_bytes = self.position() - i;
 414
 415         // Encode DefPathTable
 416         i = self.position();
 417         let def_path_table = self.encode_def_path_table();
 418         let def_path_table_bytes = self.position() - i;
 419
 420         // Encode the def IDs of impls, for coherence checking.
 421         i = self.position();
 422         let impls = self.encode_impls();
 423         let impl_bytes = self.position() - i;
 424
 425         // Encode exported symbols info.
 426         i = self.position();
 427         let exported_symbols = self.tcx.exported_symbols(LOCAL_CRATE);
 428         let exported_symbols = self.encode_exported_symbols(&exported_symbols);
 429         let exported_symbols_bytes = self.position() - i;
 430
 431         let tcx = self.tcx;
 432
 433         // Encode the items.
 434         i = self.position();
 435         self.encode_info_for_items();
 436         let item_bytes = self.position() - i;
 437
 438         // Encode the allocation index
 439         let interpret_alloc_index = {
 440             let mut interpret_alloc_index = Vec::new();
 441             let mut n = 0;
 442             trace!("beginning to encode alloc ids");
 443             loop {
 444                 let new_n = self.interpret_allocs_inverse.len();
 445                 // if we have found new ids, serialize those, too
 446                 if n == new_n {
 447                     // otherwise, abort
 448                     break;
 449                 }
 450                 trace!("encoding {} further alloc ids", new_n - n);
 451                 for idx in n..new_n {
 452                     let id = self.interpret_allocs_inverse[idx];
 453                     let pos = self.position() as u32;
 454                     interpret_alloc_index.push(pos);
 455                     interpret::specialized_encode_alloc_id(
 456                         self,
 457                         tcx,
 458                         id,
 459                     ).unwrap();
 460                 }
 461                 n = new_n;
 462             }
 463             self.lazy_seq(interpret_alloc_index)
 464         };
 465
 466         i = self.position();
 467         let entries_index = self.entries_index.write_index(&mut self.opaque);
 468         let entries_index_bytes = self.position() - i;
 469
 470         let attrs = tcx.hir().krate_attrs();
 471         let is_proc_macro = tcx.sess.crate_types.borrow().contains(&CrateType::ProcMacro);
 472         let has_default_lib_allocator = attr::contains_name(&attrs, sym::default_lib_allocator);
 473         let has_global_allocator = *tcx.sess.has_global_allocator.get();
 474         let has_panic_handler = *tcx.sess.has_panic_handler.try_get().unwrap_or(&false);
 475
 476         let root = self.lazy(&CrateRoot {
 477             name: tcx.crate_name(LOCAL_CRATE),
 478             extra_filename: tcx.sess.opts.cg.extra_filename.clone(),
 479             triple: tcx.sess.opts.target_triple.clone(),
 480             hash: tcx.crate_hash(LOCAL_CRATE),
 481             disambiguator: tcx.sess.local_crate_disambiguator(),
 482             panic_strategy: tcx.sess.panic_strategy(),
 483             edition: tcx.sess.edition(),
 484             has_global_allocator: has_global_allocator,
 485             has_panic_handler: has_panic_handler,
 486             has_default_lib_allocator: has_default_lib_allocator,
 487             plugin_registrar_fn: tcx.plugin_registrar_fn(LOCAL_CRATE).map(|id| id.index),
 488             proc_macro_decls_static: if is_proc_macro {
 489                 let id = tcx.proc_macro_decls_static(LOCAL_CRATE).unwrap();
 490                 Some(id.index)
 491             } else {
 492                 None
 493             },
 494             proc_macro_stability: if is_proc_macro {
 495                 tcx.lookup_stability(DefId::local(CRATE_DEF_INDEX)).map(|stab| stab.clone())
 496             } else {
 497                 None
 498             },
 499             compiler_builtins: attr::contains_name(&attrs, sym::compiler_builtins),
 500             needs_allocator: attr::contains_name(&attrs, sym::needs_allocator),
 501             needs_panic_runtime: attr::contains_name(&attrs, sym::needs_panic_runtime),
 502             no_builtins: attr::contains_name(&attrs, sym::no_builtins),
 503             panic_runtime: attr::contains_name(&attrs, sym::panic_runtime),
 504             profiler_runtime: attr::contains_name(&attrs, sym::profiler_runtime),
 505             sanitizer_runtime: attr::contains_name(&attrs, sym::sanitizer_runtime),
 506             symbol_mangling_version: tcx.sess.opts.debugging_opts.symbol_mangling_version,
 507
 508             crate_deps,
 509             dylib_dependency_formats,
 510             lib_features,
 511             lang_items,
 512             lang_items_missing,
 513             native_libraries,
 514             foreign_modules,
 515             source_map,
 516             def_path_table,
 517             impls,
 518             exported_symbols,
 519             interpret_alloc_index,
 520             entries_index,
 521         });
 522
 523         let total_bytes = self.position();
 524
 525         if self.tcx.sess.meta_stats() {
 526             let mut zero_bytes = 0;
 527             for e in self.opaque.data.iter() {
 528                 if *e == 0 {
 529                     zero_bytes += 1;
 530                 }
 531             }
 532
 533             println!("metadata stats:");
 534             println!("             dep bytes: {}", dep_bytes);
 535             println!("     lib feature bytes: {}", lib_feature_bytes);
 536             println!("       lang item bytes: {}", lang_item_bytes);
 537             println!("          native bytes: {}", native_lib_bytes);
 538             println!("         source_map bytes: {}", source_map_bytes);
 539             println!("            impl bytes: {}", impl_bytes);
 540             println!("    exp. symbols bytes: {}", exported_symbols_bytes);
 541             println!("  def-path table bytes: {}", def_path_table_bytes);
 542             println!("            item bytes: {}", item_bytes);
 543             println!("   entries index bytes: {}", entries_index_bytes);
 544             println!("            zero bytes: {}", zero_bytes);
 545             println!("           total bytes: {}", total_bytes);
 546         }
 547
 548         root
 549     }
 550 }
 551
 552 impl EncodeContext<'tcx> {
 553     fn encode_variances_of(&mut self, def_id: DefId) -> LazySeq<ty::Variance> {
 554         debug!("EncodeContext::encode_variances_of({:?})", def_id);
 555         let tcx = self.tcx;
 556         self.lazy_seq_ref(&tcx.variances_of(def_id)[..])
 557     }
 558
 559     fn encode_item_type(&mut self, def_id: DefId) -> Lazy<Ty<'tcx>> {
 560         let tcx = self.tcx;
 561         let ty = tcx.type_of(def_id);
 562         debug!("EncodeContext::encode_item_type({:?}) => {:?}", def_id, ty);
 563         self.lazy(&ty)
 564     }
 565
 566     fn encode_enum_variant_info(
 567         &mut self,
 568         (enum_did, index): (DefId, VariantIdx),
 569     ) -> Entry<'tcx> {
 570         let tcx = self.tcx;
 571         let def = tcx.adt_def(enum_did);
 572         let variant = &def.variants[index];
 573         let def_id = variant.def_id;
 574         debug!("EncodeContext::encode_enum_variant_info({:?})", def_id);
 575
 576         let data = VariantData {
 577             ctor_kind: variant.ctor_kind,
 578             discr: variant.discr,
 579             // FIXME(eddyb) deduplicate these with `encode_enum_variant_ctor`.
 580             ctor: variant.ctor_def_id.map(|did| did.index),
 581             ctor_sig: if variant.ctor_kind == CtorKind::Fn {
 582                 variant.ctor_def_id.map(|ctor_def_id| self.lazy(&tcx.fn_sig(ctor_def_id)))
 583             } else {
 584                 None
 585             },
 586         };
 587
 588         let enum_id = tcx.hir().as_local_hir_id(enum_did).unwrap();
 589         let enum_vis = &tcx.hir().expect_item(enum_id).vis;
 590
 591         Entry {
 592             kind: EntryKind::Variant(self.lazy(&data)),
 593             visibility: self.lazy(&ty::Visibility::from_hir(enum_vis, enum_id, tcx)),
 594             span: self.lazy(&tcx.def_span(def_id)),
 595             attributes: self.encode_attributes(&tcx.get_attrs(def_id)),
 596             children: self.lazy_seq(variant.fields.iter().map(|f| {
 597                 assert!(f.did.is_local());
 598                 f.did.index
 599             })),
 600             stability: self.encode_stability(def_id),
 601             deprecation: self.encode_deprecation(def_id),
 602
 603             ty: Some(self.encode_item_type(def_id)),
 604             inherent_impls: LazySeq::empty(),
 605             variances: if variant.ctor_kind == CtorKind::Fn {
 606                 self.encode_variances_of(def_id)
 607             } else {
 608                 LazySeq::empty()
 609             },
 610             generics: Some(self.encode_generics(def_id)),
 611             predicates: Some(self.encode_predicates(def_id)),
 612             predicates_defined_on: None,
 613
 614             mir: self.encode_optimized_mir(def_id),
 615         }
 616     }
 617
 618     fn encode_enum_variant_ctor(
 619         &mut self,
 620         (enum_did, index): (DefId, VariantIdx),
 621     ) -> Entry<'tcx> {
 622         let tcx = self.tcx;
 623         let def = tcx.adt_def(enum_did);
 624         let variant = &def.variants[index];
 625         let def_id = variant.ctor_def_id.unwrap();
 626         debug!("EncodeContext::encode_enum_variant_ctor({:?})", def_id);
 627
 628         let data = VariantData {
 629             ctor_kind: variant.ctor_kind,
 630             discr: variant.discr,
 631             ctor: Some(def_id.index),
 632             ctor_sig: if variant.ctor_kind == CtorKind::Fn {
 633                 Some(self.lazy(&tcx.fn_sig(def_id)))
 634             } else {
 635                 None
 636             }
 637         };
 638
 639         // Variant constructors have the same visibility as the parent enums, unless marked as
 640         // non-exhaustive, in which case they are lowered to `pub(crate)`.
 641         let enum_id = tcx.hir().as_local_hir_id(enum_did).unwrap();
 642         let enum_vis = &tcx.hir().expect_item(enum_id).vis;
 643         let mut ctor_vis = ty::Visibility::from_hir(enum_vis, enum_id, tcx);
 644         if variant.is_field_list_non_exhaustive() && ctor_vis == ty::Visibility::Public {
 645             ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 646         }
 647
 648         Entry {
 649             kind: EntryKind::Variant(self.lazy(&data)),
 650             visibility: self.lazy(&ctor_vis),
 651             span: self.lazy(&tcx.def_span(def_id)),
 652             attributes: LazySeq::empty(),
 653             children: LazySeq::empty(),
 654             stability: self.encode_stability(def_id),
 655             deprecation: self.encode_deprecation(def_id),
 656
 657             ty: Some(self.encode_item_type(def_id)),
 658             inherent_impls: LazySeq::empty(),
 659             variances: if variant.ctor_kind == CtorKind::Fn {
 660                 self.encode_variances_of(def_id)
 661             } else {
 662                 LazySeq::empty()
 663             },
 664             generics: Some(self.encode_generics(def_id)),
 665             predicates: Some(self.encode_predicates(def_id)),
 666             predicates_defined_on: None,
 667
 668             mir: self.encode_optimized_mir(def_id),
 669         }
 670     }
 671
 672     fn encode_info_for_mod(
 673         &mut self,
 674         (id, md, attrs, vis): (hir::HirId, &hir::Mod, &[ast::Attribute], &hir::Visibility),
 675     ) -> Entry<'tcx> {
 676         let tcx = self.tcx;
 677         let def_id = tcx.hir().local_def_id(id);
 678         debug!("EncodeContext::encode_info_for_mod({:?})", def_id);
 679
 680         let data = ModData {
 681             reexports: match tcx.module_exports(def_id) {
 682                 Some(exports) => self.lazy_seq_ref(exports),
 683                 _ => LazySeq::empty(),
 684             },
 685         };
 686
 687         Entry {
 688             kind: EntryKind::Mod(self.lazy(&data)),
 689             visibility: self.lazy(&ty::Visibility::from_hir(vis, id, tcx)),
 690             span: self.lazy(&tcx.def_span(def_id)),
 691             attributes: self.encode_attributes(attrs),
 692             children: self.lazy_seq(md.item_ids.iter().map(|item_id| {
 693                 tcx.hir().local_def_id(item_id.id).index
 694             })),
 695             stability: self.encode_stability(def_id),
 696             deprecation: self.encode_deprecation(def_id),
 697
 698             ty: None,
 699             inherent_impls: LazySeq::empty(),
 700             variances: LazySeq::empty(),
 701             generics: None,
 702             predicates: None,
 703             predicates_defined_on: None,
 704
 705             mir: None
 706         }
 707     }
 708
 709     fn encode_field(
 710         &mut self,
 711         (adt_def_id, variant_index, field_index): (DefId, VariantIdx, usize),
 712     ) -> Entry<'tcx> {
 713         let tcx = self.tcx;
 714         let variant = &tcx.adt_def(adt_def_id).variants[variant_index];
 715         let field = &variant.fields[field_index];
 716
 717         let def_id = field.did;
 718         debug!("EncodeContext::encode_field({:?})", def_id);
 719
 720         let variant_id = tcx.hir().as_local_hir_id(variant.def_id).unwrap();
 721         let variant_data = tcx.hir().expect_variant_data(variant_id);
 722
 723         Entry {
 724             kind: EntryKind::Field,
 725             visibility: self.lazy(&field.vis),
 726             span: self.lazy(&tcx.def_span(def_id)),
 727             attributes: self.encode_attributes(&variant_data.fields()[field_index].attrs),
 728             children: LazySeq::empty(),
 729             stability: self.encode_stability(def_id),
 730             deprecation: self.encode_deprecation(def_id),
 731
 732             ty: Some(self.encode_item_type(def_id)),
 733             inherent_impls: LazySeq::empty(),
 734             variances: LazySeq::empty(),
 735             generics: Some(self.encode_generics(def_id)),
 736             predicates: Some(self.encode_predicates(def_id)),
 737             predicates_defined_on: None,
 738
 739             mir: None,
 740         }
 741     }
 742
 743     fn encode_struct_ctor(&mut self, (adt_def_id, def_id): (DefId, DefId)) -> Entry<'tcx> {
 744         debug!("EncodeContext::encode_struct_ctor({:?})", def_id);
 745         let tcx = self.tcx;
 746         let adt_def = tcx.adt_def(adt_def_id);
 747         let variant = adt_def.non_enum_variant();
 748
 749         let data = VariantData {
 750             ctor_kind: variant.ctor_kind,
 751             discr: variant.discr,
 752             ctor: Some(def_id.index),
 753             ctor_sig: if variant.ctor_kind == CtorKind::Fn {
 754                 Some(self.lazy(&tcx.fn_sig(def_id)))
 755             } else {
 756                 None
 757             }
 758         };
 759
 760         let struct_id = tcx.hir().as_local_hir_id(adt_def_id).unwrap();
 761         let struct_vis = &tcx.hir().expect_item(struct_id).vis;
 762         let mut ctor_vis = ty::Visibility::from_hir(struct_vis, struct_id, tcx);
 763         for field in &variant.fields {
 764             if ctor_vis.is_at_least(field.vis, tcx) {
 765                 ctor_vis = field.vis;
 766             }
 767         }
 768
 769         // If the structure is marked as non_exhaustive then lower the visibility
 770         // to within the crate.
 771         if adt_def.non_enum_variant().is_field_list_non_exhaustive() &&
 772             ctor_vis == ty::Visibility::Public
 773         {
 774             ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 775         }
 776
 777         let repr_options = get_repr_options(tcx, adt_def_id);
 778
 779         Entry {
 780             kind: EntryKind::Struct(self.lazy(&data), repr_options),
 781             visibility: self.lazy(&ctor_vis),
 782             span: self.lazy(&tcx.def_span(def_id)),
 783             attributes: LazySeq::empty(),
 784             children: LazySeq::empty(),
 785             stability: self.encode_stability(def_id),
 786             deprecation: self.encode_deprecation(def_id),
 787
 788             ty: Some(self.encode_item_type(def_id)),
 789             inherent_impls: LazySeq::empty(),
 790             variances: if variant.ctor_kind == CtorKind::Fn {
 791                 self.encode_variances_of(def_id)
 792             } else {
 793                 LazySeq::empty()
 794             },
 795             generics: Some(self.encode_generics(def_id)),
 796             predicates: Some(self.encode_predicates(def_id)),
 797             predicates_defined_on: None,
 798
 799             mir: self.encode_optimized_mir(def_id),
 800         }
 801     }
 802
 803     fn encode_generics(&mut self, def_id: DefId) -> Lazy<ty::Generics> {
 804         debug!("EncodeContext::encode_generics({:?})", def_id);
 805         let tcx = self.tcx;
 806         self.lazy(tcx.generics_of(def_id))
 807     }
 808
 809     fn encode_predicates(&mut self, def_id: DefId) -> Lazy<ty::GenericPredicates<'tcx>> {
 810         debug!("EncodeContext::encode_predicates({:?})", def_id);
 811         let tcx = self.tcx;
 812         self.lazy(&tcx.predicates_of(def_id))
 813     }
 814
 815     fn encode_predicates_defined_on(&mut self, def_id: DefId) -> Lazy<ty::GenericPredicates<'tcx>> {
 816         debug!("EncodeContext::encode_predicates_defined_on({:?})", def_id);
 817         let tcx = self.tcx;
 818         self.lazy(&tcx.predicates_defined_on(def_id))
 819     }
 820
 821     fn encode_info_for_trait_item(&mut self, def_id: DefId) -> Entry<'tcx> {
 822         debug!("EncodeContext::encode_info_for_trait_item({:?})", def_id);
 823         let tcx = self.tcx;
 824
 825         let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
 826         let ast_item = tcx.hir().expect_trait_item(hir_id);
 827         let trait_item = tcx.associated_item(def_id);
 828
 829         let container = match trait_item.defaultness {
 830             hir::Defaultness::Default { has_value: true } =>
 831                 AssocContainer::TraitWithDefault,
 832             hir::Defaultness::Default { has_value: false } =>
 833                 AssocContainer::TraitRequired,
 834             hir::Defaultness::Final =>
 835                 span_bug!(ast_item.span, "traits cannot have final items"),
 836         };
 837
 838         let kind = match trait_item.kind {
 839             ty::AssocKind::Const => {
 840                 let const_qualif =
 841                     if let hir::TraitItemKind::Const(_, Some(body)) = ast_item.node {
 842                         self.const_qualif(0, body)
 843                     } else {
 844                         ConstQualif { mir: 0, ast_promotable: false }
 845                     };
 846
 847                 let rendered =
 848                     hir::print::to_string(self.tcx.hir(), |s| s.print_trait_item(ast_item));
 849                 let rendered_const = self.lazy(&RenderedConst(rendered));
 850
 851                 EntryKind::AssocConst(container, const_qualif, rendered_const)
 852             }
 853             ty::AssocKind::Method => {
 854                 let fn_data = if let hir::TraitItemKind::Method(_, ref m) = ast_item.node {
 855                     let arg_names = match *m {
 856                         hir::TraitMethod::Required(ref names) => {
 857                             self.encode_fn_arg_names(names)
 858                         }
 859                         hir::TraitMethod::Provided(body) => {
 860                             self.encode_fn_arg_names_for_body(body)
 861                         }
 862                     };
 863                     FnData {
 864                         constness: hir::Constness::NotConst,
 865                         arg_names,
 866                         sig: self.lazy(&tcx.fn_sig(def_id)),
 867                     }
 868                 } else {
 869                     bug!()
 870                 };
 871                 EntryKind::Method(self.lazy(&MethodData {
 872                     fn_data,
 873                     container,
 874                     has_self: trait_item.method_has_self_argument,
 875                 }))
 876             }
 877             ty::AssocKind::Type => EntryKind::AssocType(container),
 878             ty::AssocKind::OpaqueTy => span_bug!(ast_item.span, "opaque type in trait"),
 879         };
 880
 881         Entry {
 882             kind,
 883             visibility: self.lazy(&trait_item.vis),
 884             span: self.lazy(&ast_item.span),
 885             attributes: self.encode_attributes(&ast_item.attrs),
 886             children: LazySeq::empty(),
 887             stability: self.encode_stability(def_id),
 888             deprecation: self.encode_deprecation(def_id),
 889
 890             ty: match trait_item.kind {
 891                 ty::AssocKind::Const |
 892                 ty::AssocKind::Method => {
 893                     Some(self.encode_item_type(def_id))
 894                 }
 895                 ty::AssocKind::Type => {
 896                     if trait_item.defaultness.has_value() {
 897                         Some(self.encode_item_type(def_id))
 898                     } else {
 899                         None
 900                     }
 901                 }
 902                 ty::AssocKind::OpaqueTy => unreachable!(),
 903             },
 904             inherent_impls: LazySeq::empty(),
 905             variances: if trait_item.kind == ty::AssocKind::Method {
 906                 self.encode_variances_of(def_id)
 907             } else {
 908                 LazySeq::empty()
 909             },
 910             generics: Some(self.encode_generics(def_id)),
 911             predicates: Some(self.encode_predicates(def_id)),
 912             predicates_defined_on: None,
 913
 914             mir: self.encode_optimized_mir(def_id),
 915         }
 916     }
 917
 918     fn metadata_output_only(&self) -> bool {
 919         // MIR optimisation can be skipped when we're just interested in the metadata.
 920         !self.tcx.sess.opts.output_types.should_codegen()
 921     }
 922
 923     fn const_qualif(&self, mir: u8, body_id: hir::BodyId) -> ConstQualif {
 924         let body_owner_def_id = self.tcx.hir().body_owner_def_id(body_id);
 925         let ast_promotable = self.tcx.const_is_rvalue_promotable_to_static(body_owner_def_id);
 926
 927         ConstQualif { mir, ast_promotable }
 928     }
 929
 930     fn encode_info_for_impl_item(&mut self, def_id: DefId) -> Entry<'tcx> {
 931         debug!("EncodeContext::encode_info_for_impl_item({:?})", def_id);
 932         let tcx = self.tcx;
 933
 934         let hir_id = self.tcx.hir().as_local_hir_id(def_id).unwrap();
 935         let ast_item = self.tcx.hir().expect_impl_item(hir_id);
 936         let impl_item = self.tcx.associated_item(def_id);
 937
 938         let container = match impl_item.defaultness {
 939             hir::Defaultness::Default { has_value: true } => AssocContainer::ImplDefault,
 940             hir::Defaultness::Final => AssocContainer::ImplFinal,
 941             hir::Defaultness::Default { has_value: false } =>
 942                 span_bug!(ast_item.span, "impl items always have values (currently)"),
 943         };
 944
 945         let kind = match impl_item.kind {
 946             ty::AssocKind::Const => {
 947                 if let hir::ImplItemKind::Const(_, body_id) = ast_item.node {
 948                     let mir = self.tcx.at(ast_item.span).mir_const_qualif(def_id).0;
 949
 950                     EntryKind::AssocConst(container,
 951                         self.const_qualif(mir, body_id),
 952                         self.encode_rendered_const_for_body(body_id))
 953                 } else {
 954                     bug!()
 955                 }
 956             }
 957             ty::AssocKind::Method => {
 958                 let fn_data = if let hir::ImplItemKind::Method(ref sig, body) = ast_item.node {
 959                     FnData {
 960                         constness: sig.header.constness,
 961                         arg_names: self.encode_fn_arg_names_for_body(body),
 962                         sig: self.lazy(&tcx.fn_sig(def_id)),
 963                     }
 964                 } else {
 965                     bug!()
 966                 };
 967                 EntryKind::Method(self.lazy(&MethodData {
 968                     fn_data,
 969                     container,
 970                     has_self: impl_item.method_has_self_argument,
 971                 }))
 972             }
 973             ty::AssocKind::OpaqueTy => EntryKind::AssocOpaqueTy(container),
 974             ty::AssocKind::Type => EntryKind::AssocType(container)
 975         };
 976
 977         let mir =
 978             match ast_item.node {
 979                 hir::ImplItemKind::Const(..) => true,
 980                 hir::ImplItemKind::Method(ref sig, _) => {
 981                     let generics = self.tcx.generics_of(def_id);
 982                     let needs_inline = (generics.requires_monomorphization(self.tcx) ||
 983                                         tcx.codegen_fn_attrs(def_id).requests_inline()) &&
 984                                         !self.metadata_output_only();
 985                     let is_const_fn = sig.header.constness == hir::Constness::Const;
 986                     let always_encode_mir = self.tcx.sess.opts.debugging_opts.always_encode_mir;
 987                     needs_inline || is_const_fn || always_encode_mir
 988                 },
 989                 hir::ImplItemKind::OpaqueTy(..) |
 990                 hir::ImplItemKind::TyAlias(..) => false,
 991             };
 992
 993         Entry {
 994             kind,
 995             visibility: self.lazy(&impl_item.vis),
 996             span: self.lazy(&ast_item.span),
 997             attributes: self.encode_attributes(&ast_item.attrs),
 998             children: LazySeq::empty(),
 999             stability: self.encode_stability(def_id),
1000             deprecation: self.encode_deprecation(def_id),
1001
1002             ty: Some(self.encode_item_type(def_id)),
1003             inherent_impls: LazySeq::empty(),
1004             variances: if impl_item.kind == ty::AssocKind::Method {
1005                 self.encode_variances_of(def_id)
1006             } else {
1007                 LazySeq::empty()
1008             },
1009             generics: Some(self.encode_generics(def_id)),
1010             predicates: Some(self.encode_predicates(def_id)),
1011             predicates_defined_on: None,
1012
1013             mir: if mir { self.encode_optimized_mir(def_id) } else { None },
1014         }
1015     }
1016
1017     fn encode_fn_arg_names_for_body(&mut self, body_id: hir::BodyId)
1018                                     -> LazySeq<ast::Name> {
1019         self.tcx.dep_graph.with_ignore(|| {
1020             let body = self.tcx.hir().body(body_id);
1021             self.lazy_seq(body.arguments.iter().map(|arg| {
1022                 match arg.pat.node {
1023                     PatKind::Binding(_, _, ident, _) => ident.name,
1024                     _ => kw::Invalid,
1025                 }
1026             }))
1027         })
1028     }
1029
1030     fn encode_fn_arg_names(&mut self, param_names: &[ast::Ident]) -> LazySeq<ast::Name> {
1031         self.lazy_seq(param_names.iter().map(|ident| ident.name))
1032     }
1033
1034     fn encode_optimized_mir(&mut self, def_id: DefId) -> Option<Lazy<mir::Body<'tcx>>> {
1035         debug!("EntryBuilder::encode_mir({:?})", def_id);
1036         if self.tcx.mir_keys(LOCAL_CRATE).contains(&def_id) {
1037             let mir = self.tcx.optimized_mir(def_id);
1038             Some(self.lazy(&mir))
1039         } else {
1040             None
1041         }
1042     }
1043
1044     // Encodes the inherent implementations of a structure, enumeration, or trait.
1045     fn encode_inherent_implementations(&mut self, def_id: DefId) -> LazySeq<DefIndex> {
1046         debug!("EncodeContext::encode_inherent_implementations({:?})", def_id);
1047         let implementations = self.tcx.inherent_impls(def_id);
1048         if implementations.is_empty() {
1049             LazySeq::empty()
1050         } else {
1051             self.lazy_seq(implementations.iter().map(|&def_id| {
1052                 assert!(def_id.is_local());
1053                 def_id.index
1054             }))
1055         }
1056     }
1057
1058     fn encode_stability(&mut self, def_id: DefId) -> Option<Lazy<attr::Stability>> {
1059         debug!("EncodeContext::encode_stability({:?})", def_id);
1060         self.tcx.lookup_stability(def_id).map(|stab| self.lazy(stab))
1061     }
1062
1063     fn encode_deprecation(&mut self, def_id: DefId) -> Option<Lazy<attr::Deprecation>> {
1064         debug!("EncodeContext::encode_deprecation({:?})", def_id);
1065         self.tcx.lookup_deprecation(def_id).map(|depr| self.lazy(&depr))
1066     }
1067
1068     fn encode_rendered_const_for_body(&mut self, body_id: hir::BodyId) -> Lazy<RenderedConst> {
1069         let body = self.tcx.hir().body(body_id);
1070         let rendered = hir::print::to_string(self.tcx.hir(), |s| s.print_expr(&body.value));
1071         let rendered_const = &RenderedConst(rendered);
1072         self.lazy(rendered_const)
1073     }
1074
1075     fn encode_info_for_item(&mut self, (def_id, item): (DefId, &'tcx hir::Item)) -> Entry<'tcx> {
1076         let tcx = self.tcx;
1077
1078         debug!("EncodeContext::encode_info_for_item({:?})", def_id);
1079
1080         let kind = match item.node {
1081             hir::ItemKind::Static(_, hir::MutMutable, _) => EntryKind::MutStatic,
1082             hir::ItemKind::Static(_, hir::MutImmutable, _) => EntryKind::ImmStatic,
1083             hir::ItemKind::Const(_, body_id) => {
1084                 let mir = tcx.at(item.span).mir_const_qualif(def_id).0;
1085                 EntryKind::Const(
1086                     self.const_qualif(mir, body_id),
1087                     self.encode_rendered_const_for_body(body_id)
1088                 )
1089             }
1090             hir::ItemKind::Fn(_, header, .., body) => {
1091                 let data = FnData {
1092                     constness: header.constness,
1093                     arg_names: self.encode_fn_arg_names_for_body(body),
1094                     sig: self.lazy(&tcx.fn_sig(def_id)),
1095                 };
1096
1097                 EntryKind::Fn(self.lazy(&data))
1098             }
1099             hir::ItemKind::Mod(ref m) => {
1100                 return self.encode_info_for_mod((item.hir_id, m, &item.attrs, &item.vis));
1101             }
1102             hir::ItemKind::ForeignMod(_) => EntryKind::ForeignMod,
1103             hir::ItemKind::GlobalAsm(..) => EntryKind::GlobalAsm,
1104             hir::ItemKind::TyAlias(..) => EntryKind::Type,
1105             hir::ItemKind::OpaqueTy(..) => EntryKind::OpaqueTy,
1106             hir::ItemKind::Enum(..) => EntryKind::Enum(get_repr_options(tcx, def_id)),
1107             hir::ItemKind::Struct(ref struct_def, _) => {
1108                 let variant = tcx.adt_def(def_id).non_enum_variant();
1109
1110                 // Encode def_ids for each field and method
1111                 // for methods, write all the stuff get_trait_method
1112                 // needs to know
1113                 let ctor = struct_def.ctor_hir_id()
1114                     .map(|ctor_hir_id| tcx.hir().local_def_id(ctor_hir_id).index);
1115
1116                 let repr_options = get_repr_options(tcx, def_id);
1117
1118                 EntryKind::Struct(self.lazy(&VariantData {
1119                     ctor_kind: variant.ctor_kind,
1120                     discr: variant.discr,
1121                     ctor,
1122                     ctor_sig: None,
1123                 }), repr_options)
1124             }
1125             hir::ItemKind::Union(..) => {
1126                 let variant = tcx.adt_def(def_id).non_enum_variant();
1127                 let repr_options = get_repr_options(tcx, def_id);
1128
1129                 EntryKind::Union(self.lazy(&VariantData {
1130                     ctor_kind: variant.ctor_kind,
1131                     discr: variant.discr,
1132                     ctor: None,
1133                     ctor_sig: None,
1134                 }), repr_options)
1135             }
1136             hir::ItemKind::Impl(_, polarity, defaultness, ..) => {
1137                 let trait_ref = tcx.impl_trait_ref(def_id);
1138                 let parent = if let Some(trait_ref) = trait_ref {
1139                     let trait_def = tcx.trait_def(trait_ref.def_id);
1140                     trait_def.ancestors(tcx, def_id).nth(1).and_then(|node| {
1141                         match node {
1142                             specialization_graph::Node::Impl(parent) => Some(parent),
1143                             _ => None,
1144                         }
1145                     })
1146                 } else {
1147                     None
1148                 };
1149
1150                 // if this is an impl of `CoerceUnsized`, create its
1151                 // "unsized info", else just store None
1152                 let coerce_unsized_info =
1153                     trait_ref.and_then(|t| {
1154                         if Some(t.def_id) == tcx.lang_items().coerce_unsized_trait() {
1155                             Some(tcx.at(item.span).coerce_unsized_info(def_id))
1156                         } else {
1157                             None
1158                         }
1159                     });
1160
1161                 let data = ImplData {
1162                     polarity,
1163                     defaultness,
1164                     parent_impl: parent,
1165                     coerce_unsized_info,
1166                     trait_ref: trait_ref.map(|trait_ref| self.lazy(&trait_ref)),
1167                 };
1168
1169                 EntryKind::Impl(self.lazy(&data))
1170             }
1171             hir::ItemKind::Trait(..) => {
1172                 let trait_def = tcx.trait_def(def_id);
1173                 let data = TraitData {
1174                     unsafety: trait_def.unsafety,
1175                     paren_sugar: trait_def.paren_sugar,
1176                     has_auto_impl: tcx.trait_is_auto(def_id),
1177                     is_marker: trait_def.is_marker,
1178                     super_predicates: self.lazy(&tcx.super_predicates_of(def_id)),
1179                 };
1180
1181                 EntryKind::Trait(self.lazy(&data))
1182             }
1183             hir::ItemKind::TraitAlias(..) => {
1184                 let data = TraitAliasData {
1185                     super_predicates: self.lazy(&tcx.super_predicates_of(def_id)),
1186                 };
1187
1188                 EntryKind::TraitAlias(self.lazy(&data))
1189             }
1190             hir::ItemKind::ExternCrate(_) |
1191             hir::ItemKind::Use(..) => bug!("cannot encode info for item {:?}", item),
1192         };
1193
1194         Entry {
1195             kind,
1196             visibility: self.lazy(&ty::Visibility::from_hir(&item.vis, item.hir_id, tcx)),
1197             span: self.lazy(&item.span),
1198             attributes: self.encode_attributes(&item.attrs),
1199             children: match item.node {
1200                 hir::ItemKind::ForeignMod(ref fm) => {
1201                     self.lazy_seq(fm.items
1202                         .iter()
1203                         .map(|foreign_item| tcx.hir().local_def_id(
1204                             foreign_item.hir_id).index))
1205                 }
1206                 hir::ItemKind::Enum(..) => {
1207                     let def = self.tcx.adt_def(def_id);
1208                     self.lazy_seq(def.variants.iter().map(|v| {
1209                         assert!(v.def_id.is_local());
1210                         v.def_id.index
1211                     }))
1212                 }
1213                 hir::ItemKind::Struct(..) |
1214                 hir::ItemKind::Union(..) => {
1215                     let def = self.tcx.adt_def(def_id);
1216                     self.lazy_seq(def.non_enum_variant().fields.iter().map(|f| {
1217                         assert!(f.did.is_local());
1218                         f.did.index
1219                     }))
1220                 }
1221                 hir::ItemKind::Impl(..) |
1222                 hir::ItemKind::Trait(..) => {
1223                     self.lazy_seq(tcx.associated_item_def_ids(def_id).iter().map(|&def_id| {
1224                         assert!(def_id.is_local());
1225                         def_id.index
1226                     }))
1227                 }
1228                 _ => LazySeq::empty(),
1229             },
1230             stability: self.encode_stability(def_id),
1231             deprecation: self.encode_deprecation(def_id),
1232
1233             ty: match item.node {
1234                 hir::ItemKind::Static(..) |
1235                 hir::ItemKind::Const(..) |
1236                 hir::ItemKind::Fn(..) |
1237                 hir::ItemKind::TyAlias(..) |
1238                 hir::ItemKind::OpaqueTy(..) |
1239                 hir::ItemKind::Enum(..) |
1240                 hir::ItemKind::Struct(..) |
1241                 hir::ItemKind::Union(..) |
1242                 hir::ItemKind::Impl(..) => Some(self.encode_item_type(def_id)),
1243                 _ => None,
1244             },
1245             inherent_impls: self.encode_inherent_implementations(def_id),
1246             variances: match item.node {
1247                 hir::ItemKind::Enum(..) |
1248                 hir::ItemKind::Struct(..) |
1249                 hir::ItemKind::Union(..) |
1250                 hir::ItemKind::Fn(..) => self.encode_variances_of(def_id),
1251                 _ => LazySeq::empty(),
1252             },
1253             generics: match item.node {
1254                 hir::ItemKind::Static(..) |
1255                 hir::ItemKind::Const(..) |
1256                 hir::ItemKind::Fn(..) |
1257                 hir::ItemKind::TyAlias(..) |
1258                 hir::ItemKind::Enum(..) |
1259                 hir::ItemKind::Struct(..) |
1260                 hir::ItemKind::Union(..) |
1261                 hir::ItemKind::Impl(..) |
1262                 hir::ItemKind::OpaqueTy(..) |
1263                 hir::ItemKind::Trait(..) => Some(self.encode_generics(def_id)),
1264                 hir::ItemKind::TraitAlias(..) => Some(self.encode_generics(def_id)),
1265                 _ => None,
1266             },
1267             predicates: match item.node {
1268                 hir::ItemKind::Static(..) |
1269                 hir::ItemKind::Const(..) |
1270                 hir::ItemKind::Fn(..) |
1271                 hir::ItemKind::TyAlias(..) |
1272                 hir::ItemKind::Enum(..) |
1273                 hir::ItemKind::Struct(..) |
1274                 hir::ItemKind::Union(..) |
1275                 hir::ItemKind::Impl(..) |
1276                 hir::ItemKind::OpaqueTy(..) |
1277                 hir::ItemKind::Trait(..) |
1278                 hir::ItemKind::TraitAlias(..) => Some(self.encode_predicates(def_id)),
1279                 _ => None,
1280             },
1281
1282             // The only time that `predicates_defined_on` is used (on
1283             // an external item) is for traits, during chalk lowering,
1284             // so only encode it in that case as an efficiency
1285             // hack. (No reason not to expand it in the future if
1286             // necessary.)
1287             predicates_defined_on: match item.node {
1288                 hir::ItemKind::Trait(..) |
1289                 hir::ItemKind::TraitAlias(..) => Some(self.encode_predicates_defined_on(def_id)),
1290                 _ => None, // not *wrong* for other kinds of items, but not needed
1291             },
1292
1293             mir: match item.node {
1294                 hir::ItemKind::Static(..) => {
1295                     self.encode_optimized_mir(def_id)
1296                 }
1297                 hir::ItemKind::Const(..) => self.encode_optimized_mir(def_id),
1298                 hir::ItemKind::Fn(_, header, ..) => {
1299                     let generics = tcx.generics_of(def_id);
1300                     let needs_inline =
1301                         (generics.requires_monomorphization(tcx) ||
1302                          tcx.codegen_fn_attrs(def_id).requests_inline()) &&
1303                             !self.metadata_output_only();
1304                     let always_encode_mir = self.tcx.sess.opts.debugging_opts.always_encode_mir;
1305                     if needs_inline
1306                         || header.constness == hir::Constness::Const
1307                         || always_encode_mir
1308                     {
1309                         self.encode_optimized_mir(def_id)
1310                     } else {
1311                         None
1312                     }
1313                 }
1314                 _ => None,
1315             },
1316         }
1317     }
1318
1319     /// Serialize the text of exported macros
1320     fn encode_info_for_macro_def(&mut self, macro_def: &hir::MacroDef) -> Entry<'tcx> {
1321         use syntax::print::pprust;
1322         let def_id = self.tcx.hir().local_def_id(macro_def.hir_id);
1323         Entry {
1324             kind: EntryKind::MacroDef(self.lazy(&MacroDef {
1325                 body: pprust::tokens_to_string(macro_def.body.clone()),
1326                 legacy: macro_def.legacy,
1327             })),
1328             visibility: self.lazy(&ty::Visibility::Public),
1329             span: self.lazy(&macro_def.span),
1330             attributes: self.encode_attributes(&macro_def.attrs),
1331             stability: self.encode_stability(def_id),
1332             deprecation: self.encode_deprecation(def_id),
1333
1334             children: LazySeq::empty(),
1335             ty: None,
1336             inherent_impls: LazySeq::empty(),
1337             variances: LazySeq::empty(),
1338             generics: None,
1339             predicates: None,
1340             predicates_defined_on: None,
1341             mir: None,
1342         }
1343     }
1344
1345     fn encode_info_for_generic_param(
1346         &mut self,
1347         def_id: DefId,
1348         entry_kind: EntryKind<'tcx>,
1349         encode_type: bool,
1350     ) -> Entry<'tcx> {
1351         let tcx = self.tcx;
1352         Entry {
1353             kind: entry_kind,
1354             visibility: self.lazy(&ty::Visibility::Public),
1355             span: self.lazy(&tcx.def_span(def_id)),
1356             attributes: LazySeq::empty(),
1357             children: LazySeq::empty(),
1358             stability: None,
1359             deprecation: None,
1360             ty: if encode_type { Some(self.encode_item_type(def_id)) } else { None },
1361             inherent_impls: LazySeq::empty(),
1362             variances: LazySeq::empty(),
1363             generics: None,
1364             predicates: None,
1365             predicates_defined_on: None,
1366
1367             mir: None,
1368         }
1369     }
1370
1371     fn encode_info_for_ty_param(
1372         &mut self,
1373         (def_id, encode_type): (DefId, bool),
1374     ) -> Entry<'tcx> {
1375         debug!("EncodeContext::encode_info_for_ty_param({:?})", def_id);
1376         self.encode_info_for_generic_param(def_id, EntryKind::TypeParam, encode_type)
1377     }
1378
1379     fn encode_info_for_const_param(
1380         &mut self,
1381         def_id: DefId,
1382     ) -> Entry<'tcx> {
1383         debug!("EncodeContext::encode_info_for_const_param({:?})", def_id);
1384         self.encode_info_for_generic_param(def_id, EntryKind::ConstParam, true)
1385     }
1386
1387     fn encode_info_for_closure(&mut self, def_id: DefId) -> Entry<'tcx> {
1388         debug!("EncodeContext::encode_info_for_closure({:?})", def_id);
1389         let tcx = self.tcx;
1390
1391         let tables = self.tcx.typeck_tables_of(def_id);
1392         let hir_id = self.tcx.hir().as_local_hir_id(def_id).unwrap();
1393         let kind = match tables.node_type(hir_id).sty {
1394             ty::Generator(def_id, ..) => {
1395                 let layout = self.tcx.generator_layout(def_id);
1396                 let data = GeneratorData {
1397                     layout: layout.clone(),
1398                 };
1399                 EntryKind::Generator(self.lazy(&data))
1400             }
1401
1402             ty::Closure(def_id, substs) => {
1403                 let sig = substs.closure_sig(def_id, self.tcx);
1404                 let data = ClosureData { sig: self.lazy(&sig) };
1405                 EntryKind::Closure(self.lazy(&data))
1406             }
1407
1408             _ => bug!("closure that is neither generator nor closure")
1409         };
1410
1411         Entry {
1412             kind,
1413             visibility: self.lazy(&ty::Visibility::Public),
1414             span: self.lazy(&tcx.def_span(def_id)),
1415             attributes: self.encode_attributes(&tcx.get_attrs(def_id)),
1416             children: LazySeq::empty(),
1417             stability: None,
1418             deprecation: None,
1419
1420             ty: Some(self.encode_item_type(def_id)),
1421             inherent_impls: LazySeq::empty(),
1422             variances: LazySeq::empty(),
1423             generics: Some(self.encode_generics(def_id)),
1424             predicates: None,
1425             predicates_defined_on: None,
1426
1427             mir: self.encode_optimized_mir(def_id),
1428         }
1429     }
1430
1431     fn encode_info_for_anon_const(&mut self, def_id: DefId) -> Entry<'tcx> {
1432         debug!("EncodeContext::encode_info_for_anon_const({:?})", def_id);
1433         let tcx = self.tcx;
1434         let id = tcx.hir().as_local_hir_id(def_id).unwrap();
1435         let body_id = tcx.hir().body_owned_by(id);
1436         let const_data = self.encode_rendered_const_for_body(body_id);
1437         let mir = tcx.mir_const_qualif(def_id).0;
1438
1439         Entry {
1440             kind: EntryKind::Const(self.const_qualif(mir, body_id), const_data),
1441             visibility: self.lazy(&ty::Visibility::Public),
1442             span: self.lazy(&tcx.def_span(def_id)),
1443             attributes: LazySeq::empty(),
1444             children: LazySeq::empty(),
1445             stability: None,
1446             deprecation: None,
1447
1448             ty: Some(self.encode_item_type(def_id)),
1449             inherent_impls: LazySeq::empty(),
1450             variances: LazySeq::empty(),
1451             generics: Some(self.encode_generics(def_id)),
1452             predicates: Some(self.encode_predicates(def_id)),
1453             predicates_defined_on: None,
1454
1455             mir: self.encode_optimized_mir(def_id),
1456         }
1457     }
1458
1459     fn encode_attributes(&mut self, attrs: &[ast::Attribute]) -> LazySeq<ast::Attribute> {
1460         self.lazy_seq_ref(attrs)
1461     }
1462
1463     fn encode_native_libraries(&mut self) -> LazySeq<NativeLibrary> {
1464         let used_libraries = self.tcx.native_libraries(LOCAL_CRATE);
1465         self.lazy_seq(used_libraries.iter().cloned())
1466     }
1467
1468     fn encode_foreign_modules(&mut self) -> LazySeq<ForeignModule> {
1469         let foreign_modules = self.tcx.foreign_modules(LOCAL_CRATE);
1470         self.lazy_seq(foreign_modules.iter().cloned())
1471     }
1472
1473     fn encode_crate_deps(&mut self) -> LazySeq<CrateDep> {
1474         let crates = self.tcx.crates();
1475
1476         let mut deps = crates
1477             .iter()
1478             .map(|&cnum| {
1479                 let dep = CrateDep {
1480                     name: self.tcx.original_crate_name(cnum),
1481                     hash: self.tcx.crate_hash(cnum),
1482                     kind: self.tcx.dep_kind(cnum),
1483                     extra_filename: self.tcx.extra_filename(cnum),
1484                 };
1485                 (cnum, dep)
1486             })
1487             .collect::<Vec<_>>();
1488
1489         deps.sort_by_key(|&(cnum, _)| cnum);
1490
1491         {
1492             // Sanity-check the crate numbers
1493             let mut expected_cnum = 1;
1494             for &(n, _) in &deps {
1495                 assert_eq!(n, CrateNum::new(expected_cnum));
1496                 expected_cnum += 1;
1497             }
1498         }
1499
1500         // We're just going to write a list of crate 'name-hash-version's, with
1501         // the assumption that they are numbered 1 to n.
1502         // FIXME (#2166): This is not nearly enough to support correct versioning
1503         // but is enough to get transitive crate dependencies working.
1504         self.lazy_seq_ref(deps.iter().map(|&(_, ref dep)| dep))
1505     }
1506
1507     fn encode_lib_features(&mut self) -> LazySeq<(ast::Name, Option<ast::Name>)> {
1508         let tcx = self.tcx;
1509         let lib_features = tcx.lib_features();
1510         self.lazy_seq(lib_features.to_vec())
1511     }
1512
1513     fn encode_lang_items(&mut self) -> LazySeq<(DefIndex, usize)> {
1514         let tcx = self.tcx;
1515         let lang_items = tcx.lang_items();
1516         let lang_items = lang_items.items().iter();
1517         self.lazy_seq(lang_items.enumerate().filter_map(|(i, &opt_def_id)| {
1518             if let Some(def_id) = opt_def_id {
1519                 if def_id.is_local() {
1520                     return Some((def_id.index, i));
1521                 }
1522             }
1523             None
1524         }))
1525     }
1526
1527     fn encode_lang_items_missing(&mut self) -> LazySeq<lang_items::LangItem> {
1528         let tcx = self.tcx;
1529         self.lazy_seq_ref(&tcx.lang_items().missing)
1530     }
1531
1532     /// Encodes an index, mapping each trait to its (local) implementations.
1533     fn encode_impls(&mut self) -> LazySeq<TraitImpls> {
1534         debug!("EncodeContext::encode_impls()");
1535         let tcx = self.tcx;
1536         let mut visitor = ImplVisitor {
1537             tcx,
1538             impls: FxHashMap::default(),
1539         };
1540         tcx.hir().krate().visit_all_item_likes(&mut visitor);
1541
1542         let mut all_impls: Vec<_> = visitor.impls.into_iter().collect();
1543
1544         // Bring everything into deterministic order for hashing
1545         all_impls.sort_by_cached_key(|&(trait_def_id, _)| {
1546             tcx.def_path_hash(trait_def_id)
1547         });
1548
1549         let all_impls: Vec<_> = all_impls
1550             .into_iter()
1551             .map(|(trait_def_id, mut impls)| {
1552                 // Bring everything into deterministic order for hashing
1553                 impls.sort_by_cached_key(|&def_index| {
1554                     tcx.hir().definitions().def_path_hash(def_index)
1555                 });
1556
1557                 TraitImpls {
1558                     trait_id: (trait_def_id.krate.as_u32(), trait_def_id.index),
1559                     impls: self.lazy_seq_ref(&impls),
1560                 }
1561             })
1562             .collect();
1563
1564         self.lazy_seq_ref(&all_impls)
1565     }
1566
1567     // Encodes all symbols exported from this crate into the metadata.
1568     //
1569     // This pass is seeded off the reachability list calculated in the
1570     // middle::reachable module but filters out items that either don't have a
1571     // symbol associated with them (they weren't translated) or if they're an FFI
1572     // definition (as that's not defined in this crate).
1573     fn encode_exported_symbols(&mut self,
1574                                exported_symbols: &[(ExportedSymbol<'tcx>, SymbolExportLevel)])
1575                                -> LazySeq<(ExportedSymbol<'tcx>, SymbolExportLevel)> {
1576         // The metadata symbol name is special. It should not show up in
1577         // downstream crates.
1578         let metadata_symbol_name = SymbolName::new(&metadata_symbol_name(self.tcx));
1579
1580         self.lazy_seq(exported_symbols
1581             .iter()
1582             .filter(|&&(ref exported_symbol, _)| {
1583                 match *exported_symbol {
1584                     ExportedSymbol::NoDefId(symbol_name) => {
1585                         symbol_name != metadata_symbol_name
1586                     },
1587                     _ => true,
1588                 }
1589             })
1590             .cloned())
1591     }
1592
1593     fn encode_dylib_dependency_formats(&mut self) -> LazySeq<Option<LinkagePreference>> {
1594         match self.tcx.sess.dependency_formats.borrow().get(&config::CrateType::Dylib) {
1595             Some(arr) => {
1596                 self.lazy_seq(arr.iter().map(|slot| {
1597                     match *slot {
1598                         Linkage::NotLinked |
1599                         Linkage::IncludedFromDylib => None,
1600
1601                         Linkage::Dynamic => Some(LinkagePreference::RequireDynamic),
1602                         Linkage::Static => Some(LinkagePreference::RequireStatic),
1603                     }
1604                 }))
1605             }
1606             None => LazySeq::empty(),
1607         }
1608     }
1609
1610     fn encode_info_for_foreign_item(&mut self,
1611                                     (def_id, nitem): (DefId, &hir::ForeignItem))
1612                                     -> Entry<'tcx> {
1613         let tcx = self.tcx;
1614
1615         debug!("EncodeContext::encode_info_for_foreign_item({:?})", def_id);
1616
1617         let kind = match nitem.node {
1618             hir::ForeignItemKind::Fn(_, ref names, _) => {
1619                 let data = FnData {
1620                     constness: hir::Constness::NotConst,
1621                     arg_names: self.encode_fn_arg_names(names),
1622                     sig: self.lazy(&tcx.fn_sig(def_id)),
1623                 };
1624                 EntryKind::ForeignFn(self.lazy(&data))
1625             }
1626             hir::ForeignItemKind::Static(_, hir::MutMutable) => EntryKind::ForeignMutStatic,
1627             hir::ForeignItemKind::Static(_, hir::MutImmutable) => EntryKind::ForeignImmStatic,
1628             hir::ForeignItemKind::Type => EntryKind::ForeignType,
1629         };
1630
1631         Entry {
1632             kind,
1633             visibility: self.lazy(&ty::Visibility::from_hir(&nitem.vis, nitem.hir_id, tcx)),
1634             span: self.lazy(&nitem.span),
1635             attributes: self.encode_attributes(&nitem.attrs),
1636             children: LazySeq::empty(),
1637             stability: self.encode_stability(def_id),
1638             deprecation: self.encode_deprecation(def_id),
1639
1640             ty: Some(self.encode_item_type(def_id)),
1641             inherent_impls: LazySeq::empty(),
1642             variances: match nitem.node {
1643                 hir::ForeignItemKind::Fn(..) => self.encode_variances_of(def_id),
1644                 _ => LazySeq::empty(),
1645             },
1646             generics: Some(self.encode_generics(def_id)),
1647             predicates: Some(self.encode_predicates(def_id)),
1648             predicates_defined_on: None,
1649
1650             mir: None,
1651         }
1652     }
1653 }
1654
1655 impl Visitor<'tcx> for EncodeContext<'tcx> {
1656     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
1657         NestedVisitorMap::OnlyBodies(&self.tcx.hir())
1658     }
1659     fn visit_expr(&mut self, ex: &'tcx hir::Expr) {
1660         intravisit::walk_expr(self, ex);
1661         self.encode_info_for_expr(ex);
1662     }
1663     fn visit_item(&mut self, item: &'tcx hir::Item) {
1664         intravisit::walk_item(self, item);
1665         let def_id = self.tcx.hir().local_def_id(item.hir_id);
1666         match item.node {
1667             hir::ItemKind::ExternCrate(_) |
1668             hir::ItemKind::Use(..) => {} // ignore these
1669             _ => self.record(def_id, EncodeContext::encode_info_for_item, (def_id, item)),
1670         }
1671         self.encode_addl_info_for_item(item);
1672     }
1673     fn visit_foreign_item(&mut self, ni: &'tcx hir::ForeignItem) {
1674         intravisit::walk_foreign_item(self, ni);
1675         let def_id = self.tcx.hir().local_def_id(ni.hir_id);
1676         self.record(def_id,
1677                           EncodeContext::encode_info_for_foreign_item,
1678                           (def_id, ni));
1679     }
1680     fn visit_variant(&mut self,
1681                      v: &'tcx hir::Variant,
1682                      g: &'tcx hir::Generics,
1683                      id: hir::HirId) {
1684         intravisit::walk_variant(self, v, g, id);
1685
1686         if let Some(ref discr) = v.disr_expr {
1687             let def_id = self.tcx.hir().local_def_id(discr.hir_id);
1688             self.record(def_id, EncodeContext::encode_info_for_anon_const, def_id);
1689         }
1690     }
1691     fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
1692         intravisit::walk_generics(self, generics);
1693         self.encode_info_for_generics(generics);
1694     }
1695     fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
1696         intravisit::walk_ty(self, ty);
1697         self.encode_info_for_ty(ty);
1698     }
1699     fn visit_macro_def(&mut self, macro_def: &'tcx hir::MacroDef) {
1700         let def_id = self.tcx.hir().local_def_id(macro_def.hir_id);
1701         self.record(def_id, EncodeContext::encode_info_for_macro_def, macro_def);
1702     }
1703 }
1704
1705 impl EncodeContext<'tcx> {
1706     fn encode_fields(&mut self, adt_def_id: DefId) {
1707         let def = self.tcx.adt_def(adt_def_id);
1708         for (variant_index, variant) in def.variants.iter_enumerated() {
1709             for (field_index, field) in variant.fields.iter().enumerate() {
1710                 self.record(field.did,
1711                             EncodeContext::encode_field,
1712                             (adt_def_id, variant_index, field_index));
1713             }
1714         }
1715     }
1716
1717     fn encode_info_for_generics(&mut self, generics: &hir::Generics) {
1718         for param in &generics.params {
1719             let def_id = self.tcx.hir().local_def_id(param.hir_id);
1720             match param.kind {
1721                 GenericParamKind::Lifetime { .. } => continue,
1722                 GenericParamKind::Type { ref default, .. } => {
1723                     self.record(
1724                         def_id,
1725                         EncodeContext::encode_info_for_ty_param,
1726                         (def_id, default.is_some()),
1727                     );
1728                 }
1729                 GenericParamKind::Const { .. } => {
1730                     self.record(def_id, EncodeContext::encode_info_for_const_param, def_id);
1731                 }
1732             }
1733         }
1734     }
1735
1736     fn encode_info_for_ty(&mut self, ty: &hir::Ty) {
1737         match ty.node {
1738             hir::TyKind::Array(_, ref length) => {
1739                 let def_id = self.tcx.hir().local_def_id(length.hir_id);
1740                 self.record(def_id, EncodeContext::encode_info_for_anon_const, def_id);
1741             }
1742             _ => {}
1743         }
1744     }
1745
1746     fn encode_info_for_expr(&mut self, expr: &hir::Expr) {
1747         match expr.node {
1748             hir::ExprKind::Closure(..) => {
1749                 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
1750                 self.record(def_id, EncodeContext::encode_info_for_closure, def_id);
1751             }
1752             _ => {}
1753         }
1754     }
1755
1756     /// In some cases, along with the item itself, we also
1757     /// encode some sub-items. Usually we want some info from the item
1758     /// so it's easier to do that here then to wait until we would encounter
1759     /// normally in the visitor walk.
1760     fn encode_addl_info_for_item(&mut self, item: &hir::Item) {
1761         let def_id = self.tcx.hir().local_def_id(item.hir_id);
1762         match item.node {
1763             hir::ItemKind::Static(..) |
1764             hir::ItemKind::Const(..) |
1765             hir::ItemKind::Fn(..) |
1766             hir::ItemKind::Mod(..) |
1767             hir::ItemKind::ForeignMod(..) |
1768             hir::ItemKind::GlobalAsm(..) |
1769             hir::ItemKind::ExternCrate(..) |
1770             hir::ItemKind::Use(..) |
1771             hir::ItemKind::TyAlias(..) |
1772             hir::ItemKind::OpaqueTy(..) |
1773             hir::ItemKind::TraitAlias(..) => {
1774                 // no sub-item recording needed in these cases
1775             }
1776             hir::ItemKind::Enum(..) => {
1777                 self.encode_fields(def_id);
1778
1779                 let def = self.tcx.adt_def(def_id);
1780                 for (i, variant) in def.variants.iter_enumerated() {
1781                     self.record(variant.def_id,
1782                                 EncodeContext::encode_enum_variant_info,
1783                                 (def_id, i));
1784
1785                     if let Some(ctor_def_id) = variant.ctor_def_id {
1786                         self.record(ctor_def_id,
1787                                     EncodeContext::encode_enum_variant_ctor,
1788                                     (def_id, i));
1789                     }
1790                 }
1791             }
1792             hir::ItemKind::Struct(ref struct_def, _) => {
1793                 self.encode_fields(def_id);
1794
1795                 // If the struct has a constructor, encode it.
1796                 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
1797                     let ctor_def_id = self.tcx.hir().local_def_id(ctor_hir_id);
1798                     self.record(ctor_def_id,
1799                                 EncodeContext::encode_struct_ctor,
1800                                 (def_id, ctor_def_id));
1801                 }
1802             }
1803             hir::ItemKind::Union(..) => {
1804                 self.encode_fields(def_id);
1805             }
1806             hir::ItemKind::Impl(..) => {
1807                 for &trait_item_def_id in self.tcx.associated_item_def_ids(def_id).iter() {
1808                     self.record(trait_item_def_id,
1809                                 EncodeContext::encode_info_for_impl_item,
1810                                 trait_item_def_id);
1811                 }
1812             }
1813             hir::ItemKind::Trait(..) => {
1814                 for &item_def_id in self.tcx.associated_item_def_ids(def_id).iter() {
1815                     self.record(item_def_id,
1816                                 EncodeContext::encode_info_for_trait_item,
1817                                 item_def_id);
1818                 }
1819             }
1820         }
1821     }
1822 }
1823
1824 struct ImplVisitor<'tcx> {
1825     tcx: TyCtxt<'tcx>,
1826     impls: FxHashMap<DefId, Vec<DefIndex>>,
1827 }
1828
1829 impl<'tcx, 'v> ItemLikeVisitor<'v> for ImplVisitor<'tcx> {
1830     fn visit_item(&mut self, item: &hir::Item) {
1831         if let hir::ItemKind::Impl(..) = item.node {
1832             let impl_id = self.tcx.hir().local_def_id(item.hir_id);
1833             if let Some(trait_ref) = self.tcx.impl_trait_ref(impl_id) {
1834                 self.impls
1835                     .entry(trait_ref.def_id)
1836                     .or_default()
1837                     .push(impl_id.index);
1838             }
1839         }
1840     }
1841
1842     fn visit_trait_item(&mut self, _trait_item: &'v hir::TraitItem) {}
1843
1844     fn visit_impl_item(&mut self, _impl_item: &'v hir::ImplItem) {
1845         // handled in `visit_item` above
1846     }
1847 }
1848
1849 // NOTE(eddyb) The following comment was preserved for posterity, even
1850 // though it's no longer relevant as EBML (which uses nested & tagged
1851 // "documents") was replaced with a scheme that can't go out of bounds.
1852 //
1853 // And here we run into yet another obscure archive bug: in which metadata
1854 // loaded from archives may have trailing garbage bytes. Awhile back one of
1855 // our tests was failing sporadically on the macOS 64-bit builders (both nopt
1856 // and opt) by having ebml generate an out-of-bounds panic when looking at
1857 // metadata.
1858 //
1859 // Upon investigation it turned out that the metadata file inside of an rlib
1860 // (and ar archive) was being corrupted. Some compilations would generate a
1861 // metadata file which would end in a few extra bytes, while other
1862 // compilations would not have these extra bytes appended to the end. These
1863 // extra bytes were interpreted by ebml as an extra tag, so they ended up
1864 // being interpreted causing the out-of-bounds.
1865 //
1866 // The root cause of why these extra bytes were appearing was never
1867 // discovered, and in the meantime the solution we're employing is to insert
1868 // the length of the metadata to the start of the metadata. Later on this
1869 // will allow us to slice the metadata to the precise length that we just
1870 // generated regardless of trailing bytes that end up in it.
1871
1872 pub fn encode_metadata(tcx: TyCtxt<'_>) -> EncodedMetadata {
1873     let mut encoder = opaque::Encoder::new(vec![]);
1874     encoder.emit_raw_bytes(METADATA_HEADER);
1875
1876     // Will be filled with the root position after encoding everything.
1877     encoder.emit_raw_bytes(&[0, 0, 0, 0]);
1878
1879     // Since encoding metadata is not in a query, and nothing is cached,
1880     // there's no need to do dep-graph tracking for any of it.
1881     let (root, mut result) = tcx.dep_graph.with_ignore(move || {
1882         let mut ecx = EncodeContext {
1883             opaque: encoder,
1884             tcx,
1885             entries_index: Index::new(tcx.hir().definitions().def_index_count()),
1886             lazy_state: LazyState::NoNode,
1887             type_shorthands: Default::default(),
1888             predicate_shorthands: Default::default(),
1889             source_file_cache: tcx.sess.source_map().files()[0].clone(),
1890             interpret_allocs: Default::default(),
1891             interpret_allocs_inverse: Default::default(),
1892         };
1893
1894         // Encode the rustc version string in a predictable location.
1895         rustc_version().encode(&mut ecx).unwrap();
1896
1897         // Encode all the entries and extra information in the crate,
1898         // culminating in the `CrateRoot` which points to all of it.
1899         let root = ecx.encode_crate_root();
1900         (root, ecx.opaque.into_inner())
1901     });
1902
1903     // Encode the root position.
1904     let header = METADATA_HEADER.len();
1905     let pos = root.position;
1906     result[header + 0] = (pos >> 24) as u8;
1907     result[header + 1] = (pos >> 16) as u8;
1908     result[header + 2] = (pos >> 8) as u8;
1909     result[header + 3] = (pos >> 0) as u8;
1910
1911     EncodedMetadata { raw_data: result }
1912 }
1913
1914 pub fn get_repr_options(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1915     let ty = tcx.type_of(did);
1916     match ty.sty {
1917         ty::Adt(ref def, _) => return def.repr,
1918         _ => bug!("{} is not an ADT", ty),
1919     }
1920 }