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::ext::proc_macro::is_proc_macro_attr;
  34 use syntax::source_map::Spanned;
  35 use syntax::symbol::{kw, sym};
  36 use syntax_pos::{self, FileName, SourceFile, Span};
  37 use log::{debug, trace};
  38
  39 use rustc::hir::{self, PatKind};
  40 use rustc::hir::itemlikevisit::ItemLikeVisitor;
  41 use rustc::hir::intravisit::{Visitor, NestedVisitorMap};
  42 use rustc::hir::intravisit;
  43
  44 pub struct EncodeContext<'tcx> {
  45     opaque: opaque::Encoder,
  46     pub tcx: TyCtxt<'tcx>,
  47
  48     entries_index: Index<'tcx>,
  49
  50     lazy_state: LazyState,
  51     type_shorthands: FxHashMap<Ty<'tcx>, usize>,
  52     predicate_shorthands: FxHashMap<ty::Predicate<'tcx>, usize>,
  53
  54     interpret_allocs: FxHashMap<interpret::AllocId, usize>,
  55     interpret_allocs_inverse: Vec<interpret::AllocId>,
  56
  57     // This is used to speed up Span encoding.
  58     source_file_cache: Lrc<SourceFile>,
  59 }
  60
  61 macro_rules! encoder_methods {
  62     ($($name:ident($ty:ty);)*) => {
  63         $(fn $name(&mut self, value: $ty) -> Result<(), Self::Error> {
  64             self.opaque.$name(value)
  65         })*
  66     }
  67 }
  68
  69 impl<'tcx> Encoder for EncodeContext<'tcx> {
  70     type Error = <opaque::Encoder as Encoder>::Error;
  71
  72     fn emit_unit(&mut self) -> Result<(), Self::Error> {
  73         Ok(())
  74     }
  75
  76     encoder_methods! {
  77         emit_usize(usize);
  78         emit_u128(u128);
  79         emit_u64(u64);
  80         emit_u32(u32);
  81         emit_u16(u16);
  82         emit_u8(u8);
  83
  84         emit_isize(isize);
  85         emit_i128(i128);
  86         emit_i64(i64);
  87         emit_i32(i32);
  88         emit_i16(i16);
  89         emit_i8(i8);
  90
  91         emit_bool(bool);
  92         emit_f64(f64);
  93         emit_f32(f32);
  94         emit_char(char);
  95         emit_str(&str);
  96     }
  97 }
  98
  99 impl<'tcx, T> SpecializedEncoder<Lazy<T>> for EncodeContext<'tcx> {
 100     fn specialized_encode(&mut self, lazy: &Lazy<T>) -> Result<(), Self::Error> {
 101         self.emit_lazy_distance(lazy.position, Lazy::<T>::min_size())
 102     }
 103 }
 104
 105 impl<'tcx, T> SpecializedEncoder<LazySeq<T>> for EncodeContext<'tcx> {
 106     fn specialized_encode(&mut self, seq: &LazySeq<T>) -> Result<(), Self::Error> {
 107         self.emit_usize(seq.len)?;
 108         if seq.len == 0 {
 109             return Ok(());
 110         }
 111         self.emit_lazy_distance(seq.position, LazySeq::<T>::min_size(seq.len))
 112     }
 113 }
 114
 115 impl<'tcx> SpecializedEncoder<CrateNum> for EncodeContext<'tcx> {
 116     #[inline]
 117     fn specialized_encode(&mut self, cnum: &CrateNum) -> Result<(), Self::Error> {
 118         self.emit_u32(cnum.as_u32())
 119     }
 120 }
 121
 122 impl<'tcx> SpecializedEncoder<DefId> for EncodeContext<'tcx> {
 123     #[inline]
 124     fn specialized_encode(&mut self, def_id: &DefId) -> Result<(), Self::Error> {
 125         let DefId {
 126             krate,
 127             index,
 128         } = *def_id;
 129
 130         krate.encode(self)?;
 131         index.encode(self)
 132     }
 133 }
 134
 135 impl<'tcx> SpecializedEncoder<DefIndex> for EncodeContext<'tcx> {
 136     #[inline]
 137     fn specialized_encode(&mut self, def_index: &DefIndex) -> Result<(), Self::Error> {
 138         self.emit_u32(def_index.as_u32())
 139     }
 140 }
 141
 142 impl<'tcx> SpecializedEncoder<Span> for EncodeContext<'tcx> {
 143     fn specialized_encode(&mut self, span: &Span) -> Result<(), Self::Error> {
 144         if span.is_dummy() {
 145             return TAG_INVALID_SPAN.encode(self)
 146         }
 147
 148         let span = span.data();
 149
 150         // The Span infrastructure should make sure that this invariant holds:
 151         debug_assert!(span.lo <= span.hi);
 152
 153         if !self.source_file_cache.contains(span.lo) {
 154             let source_map = self.tcx.sess.source_map();
 155             let source_file_index = source_map.lookup_source_file_idx(span.lo);
 156             self.source_file_cache = source_map.files()[source_file_index].clone();
 157         }
 158
 159         if !self.source_file_cache.contains(span.hi) {
 160             // Unfortunately, macro expansion still sometimes generates Spans
 161             // that malformed in this way.
 162             return TAG_INVALID_SPAN.encode(self)
 163         }
 164
 165         TAG_VALID_SPAN.encode(self)?;
 166         span.lo.encode(self)?;
 167
 168         // Encode length which is usually less than span.hi and profits more
 169         // from the variable-length integer encoding that we use.
 170         let len = span.hi - span.lo;
 171         len.encode(self)
 172
 173         // Don't encode the expansion context.
 174     }
 175 }
 176
 177 impl<'tcx> SpecializedEncoder<LocalDefId> for EncodeContext<'tcx> {
 178     #[inline]
 179     fn specialized_encode(&mut self, def_id: &LocalDefId) -> Result<(), Self::Error> {
 180         self.specialized_encode(&def_id.to_def_id())
 181     }
 182 }
 183
 184 impl<'tcx> SpecializedEncoder<Ty<'tcx>> for EncodeContext<'tcx> {
 185     fn specialized_encode(&mut self, ty: &Ty<'tcx>) -> Result<(), Self::Error> {
 186         ty_codec::encode_with_shorthand(self, ty, |ecx| &mut ecx.type_shorthands)
 187     }
 188 }
 189
 190 impl<'tcx> SpecializedEncoder<interpret::AllocId> for EncodeContext<'tcx> {
 191     fn specialized_encode(&mut self, alloc_id: &interpret::AllocId) -> Result<(), Self::Error> {
 192         use std::collections::hash_map::Entry;
 193         let index = match self.interpret_allocs.entry(*alloc_id) {
 194             Entry::Occupied(e) => *e.get(),
 195             Entry::Vacant(e) => {
 196                 let idx = self.interpret_allocs_inverse.len();
 197                 self.interpret_allocs_inverse.push(*alloc_id);
 198                 e.insert(idx);
 199                 idx
 200             },
 201         };
 202
 203         index.encode(self)
 204     }
 205 }
 206
 207 impl<'tcx> SpecializedEncoder<ty::GenericPredicates<'tcx>> for EncodeContext<'tcx> {
 208     fn specialized_encode(&mut self,
 209                           predicates: &ty::GenericPredicates<'tcx>)
 210                           -> Result<(), Self::Error> {
 211         ty_codec::encode_predicates(self, predicates, |ecx| &mut ecx.predicate_shorthands)
 212     }
 213 }
 214
 215 impl<'tcx> SpecializedEncoder<Fingerprint> for EncodeContext<'tcx> {
 216     fn specialized_encode(&mut self, f: &Fingerprint) -> Result<(), Self::Error> {
 217         f.encode_opaque(&mut self.opaque)
 218     }
 219 }
 220
 221 impl<'tcx, T: Encodable> SpecializedEncoder<mir::ClearCrossCrate<T>> for EncodeContext<'tcx> {
 222     fn specialized_encode(&mut self,
 223                           _: &mir::ClearCrossCrate<T>)
 224                           -> Result<(), Self::Error> {
 225         Ok(())
 226     }
 227 }
 228
 229 impl<'tcx> TyEncoder for EncodeContext<'tcx> {
 230     fn position(&self) -> usize {
 231         self.opaque.position()
 232     }
 233 }
 234
 235 impl<'tcx> EncodeContext<'tcx> {
 236     fn emit_node<F: FnOnce(&mut Self, usize) -> R, R>(&mut self, f: F) -> R {
 237         assert_eq!(self.lazy_state, LazyState::NoNode);
 238         let pos = self.position();
 239         self.lazy_state = LazyState::NodeStart(pos);
 240         let r = f(self, pos);
 241         self.lazy_state = LazyState::NoNode;
 242         r
 243     }
 244
 245     fn emit_lazy_distance(&mut self,
 246                           position: usize,
 247                           min_size: usize)
 248                           -> Result<(), <Self as Encoder>::Error> {
 249         let min_end = position + min_size;
 250         let distance = match self.lazy_state {
 251             LazyState::NoNode => bug!("emit_lazy_distance: outside of a metadata node"),
 252             LazyState::NodeStart(start) => {
 253                 assert!(min_end <= start);
 254                 start - min_end
 255             }
 256             LazyState::Previous(last_min_end) => {
 257                 assert!(
 258                     last_min_end <= position,
 259                     "make sure that the calls to `lazy*` \
 260                     are in the same order as the metadata fields",
 261                 );
 262                 position - last_min_end
 263             }
 264         };
 265         self.lazy_state = LazyState::Previous(min_end);
 266         self.emit_usize(distance)
 267     }
 268
 269     pub fn lazy<T: Encodable>(&mut self, value: &T) -> Lazy<T> {
 270         self.emit_node(|ecx, pos| {
 271             value.encode(ecx).unwrap();
 272
 273             assert!(pos + Lazy::<T>::min_size() <= ecx.position());
 274             Lazy::with_position(pos)
 275         })
 276     }
 277
 278     pub fn lazy_seq<I, T>(&mut self, iter: I) -> LazySeq<T>
 279         where I: IntoIterator<Item = T>,
 280               T: Encodable
 281     {
 282         self.emit_node(|ecx, pos| {
 283             let len = iter.into_iter().map(|value| value.encode(ecx).unwrap()).count();
 284
 285             assert!(pos + LazySeq::<T>::min_size(len) <= ecx.position());
 286             LazySeq::with_position_and_length(pos, len)
 287         })
 288     }
 289
 290     pub fn lazy_seq_ref<'b, I, T>(&mut self, iter: I) -> LazySeq<T>
 291         where I: IntoIterator<Item = &'b T>,
 292               T: 'b + Encodable
 293     {
 294         self.emit_node(|ecx, pos| {
 295             let len = iter.into_iter().map(|value| value.encode(ecx).unwrap()).count();
 296
 297             assert!(pos + LazySeq::<T>::min_size(len) <= ecx.position());
 298             LazySeq::with_position_and_length(pos, len)
 299         })
 300     }
 301
 302     /// Emit the data for a `DefId` to the metadata. The function to
 303     /// emit the data is `op`, and it will be given `data` as
 304     /// arguments. This `record` function will call `op` to generate
 305     /// the `Entry` (which may point to other encoded information)
 306     /// and will then record the `Lazy<Entry>` for use in the index.
 307     // FIXME(eddyb) remove this.
 308     pub fn record<DATA>(&mut self,
 309                         id: DefId,
 310                         op: impl FnOnce(&mut Self, DATA) -> Entry<'tcx>,
 311                         data: DATA)
 312     {
 313         assert!(id.is_local());
 314
 315         let entry = op(self, data);
 316         let entry = self.lazy(&entry);
 317         self.entries_index.record(id, entry);
 318     }
 319
 320     fn encode_info_for_items(&mut self) {
 321         let krate = self.tcx.hir().krate();
 322         let vis = Spanned { span: syntax_pos::DUMMY_SP, node: hir::VisibilityKind::Public };
 323         self.record(DefId::local(CRATE_DEF_INDEX),
 324                      EncodeContext::encode_info_for_mod,
 325                      (hir::CRATE_HIR_ID, &krate.module, &krate.attrs, &vis));
 326         krate.visit_all_item_likes(&mut self.as_deep_visitor());
 327         for macro_def in &krate.exported_macros {
 328             self.visit_macro_def(macro_def);
 329         }
 330     }
 331
 332     fn encode_def_path_table(&mut self) -> Lazy<DefPathTable> {
 333         let definitions = self.tcx.hir().definitions();
 334         self.lazy(definitions.def_path_table())
 335     }
 336
 337     fn encode_source_map(&mut self) -> LazySeq<syntax_pos::SourceFile> {
 338         let source_map = self.tcx.sess.source_map();
 339         let all_source_files = source_map.files();
 340
 341         let (working_dir, _cwd_remapped) = self.tcx.sess.working_dir.clone();
 342
 343         let adapted = all_source_files.iter()
 344             .filter(|source_file| {
 345                 // No need to re-export imported source_files, as any downstream
 346                 // crate will import them from their original source.
 347                 !source_file.is_imported()
 348             })
 349             .map(|source_file| {
 350                 match source_file.name {
 351                     // This path of this SourceFile has been modified by
 352                     // path-remapping, so we use it verbatim (and avoid
 353                     // cloning the whole map in the process).
 354                     _  if source_file.name_was_remapped => source_file.clone(),
 355
 356                     // Otherwise expand all paths to absolute paths because
 357                     // any relative paths are potentially relative to a
 358                     // wrong directory.
 359                     FileName::Real(ref name) => {
 360                         let mut adapted = (**source_file).clone();
 361                         adapted.name = Path::new(&working_dir).join(name).into();
 362                         adapted.name_hash = {
 363                             let mut hasher: StableHasher<u128> = StableHasher::new();
 364                             adapted.name.hash(&mut hasher);
 365                             hasher.finish()
 366                         };
 367                         Lrc::new(adapted)
 368                     },
 369
 370                     // expanded code, not from a file
 371                     _ => source_file.clone(),
 372                 }
 373             })
 374             .collect::<Vec<_>>();
 375
 376         self.lazy_seq_ref(adapted.iter().map(|rc| &**rc))
 377     }
 378
 379     fn encode_crate_root(&mut self) -> Lazy<CrateRoot<'tcx>> {
 380         let is_proc_macro = self.tcx.sess.crate_types.borrow().contains(&CrateType::ProcMacro);
 381
 382         let mut i = self.position();
 383
 384         let crate_deps = self.encode_crate_deps();
 385         let dylib_dependency_formats = self.encode_dylib_dependency_formats();
 386         let dep_bytes = self.position() - i;
 387
 388         // Encode the lib features.
 389         i = self.position();
 390         let lib_features = self.encode_lib_features();
 391         let lib_feature_bytes = self.position() - i;
 392
 393         // Encode the language items.
 394         i = self.position();
 395         let lang_items = self.encode_lang_items();
 396         let lang_items_missing = self.encode_lang_items_missing();
 397         let lang_item_bytes = self.position() - i;
 398
 399         // Encode the native libraries used
 400         i = self.position();
 401         let native_libraries = self.encode_native_libraries();
 402         let native_lib_bytes = self.position() - i;
 403
 404         let foreign_modules = self.encode_foreign_modules();
 405
 406         // Encode source_map
 407         i = self.position();
 408         let source_map = self.encode_source_map();
 409         let source_map_bytes = self.position() - i;
 410
 411         // Encode DefPathTable
 412         i = self.position();
 413         let def_path_table = self.encode_def_path_table();
 414         let def_path_table_bytes = self.position() - i;
 415
 416         // Encode the def IDs of impls, for coherence checking.
 417         i = self.position();
 418         let impls = self.encode_impls();
 419         let impl_bytes = self.position() - i;
 420
 421         // Encode exported symbols info.
 422         i = self.position();
 423         let exported_symbols = self.tcx.exported_symbols(LOCAL_CRATE);
 424         let exported_symbols = self.encode_exported_symbols(&exported_symbols);
 425         let exported_symbols_bytes = self.position() - i;
 426
 427         let tcx = self.tcx;
 428
 429         // Encode the items.
 430         i = self.position();
 431         self.encode_info_for_items();
 432         let item_bytes = self.position() - i;
 433
 434         // Encode the allocation index
 435         let interpret_alloc_index = {
 436             let mut interpret_alloc_index = Vec::new();
 437             let mut n = 0;
 438             trace!("beginning to encode alloc ids");
 439             loop {
 440                 let new_n = self.interpret_allocs_inverse.len();
 441                 // if we have found new ids, serialize those, too
 442                 if n == new_n {
 443                     // otherwise, abort
 444                     break;
 445                 }
 446                 trace!("encoding {} further alloc ids", new_n - n);
 447                 for idx in n..new_n {
 448                     let id = self.interpret_allocs_inverse[idx];
 449                     let pos = self.position() as u32;
 450                     interpret_alloc_index.push(pos);
 451                     interpret::specialized_encode_alloc_id(
 452                         self,
 453                         tcx,
 454                         id,
 455                     ).unwrap();
 456                 }
 457                 n = new_n;
 458             }
 459             self.lazy_seq(interpret_alloc_index)
 460         };
 461
 462
 463         i = self.position();
 464         let entries_index = self.entries_index.write_index(&mut self.opaque);
 465         let entries_index_bytes = self.position() - i;
 466
 467         // Encode the proc macro data
 468         i = self.position();
 469         let proc_macro_data = self.encode_proc_macros();
 470         let proc_macro_data_bytes = self.position() - i;
 471
 472
 473         let attrs = tcx.hir().krate_attrs();
 474         let has_default_lib_allocator = attr::contains_name(&attrs, sym::default_lib_allocator);
 475         let has_global_allocator = *tcx.sess.has_global_allocator.get();
 476         let has_panic_handler = *tcx.sess.has_panic_handler.try_get().unwrap_or(&false);
 477
 478
 479         let root = self.lazy(&CrateRoot {
 480             name: tcx.crate_name(LOCAL_CRATE),
 481             extra_filename: tcx.sess.opts.cg.extra_filename.clone(),
 482             triple: tcx.sess.opts.target_triple.clone(),
 483             hash: tcx.crate_hash(LOCAL_CRATE),
 484             disambiguator: tcx.sess.local_crate_disambiguator(),
 485             panic_strategy: tcx.sess.panic_strategy(),
 486             edition: tcx.sess.edition(),
 487             has_global_allocator: has_global_allocator,
 488             has_panic_handler: has_panic_handler,
 489             has_default_lib_allocator: has_default_lib_allocator,
 490             plugin_registrar_fn: tcx.plugin_registrar_fn(LOCAL_CRATE).map(|id| id.index),
 491             proc_macro_decls_static: if is_proc_macro {
 492                 let id = tcx.proc_macro_decls_static(LOCAL_CRATE).unwrap();
 493                 Some(id.index)
 494             } else {
 495                 None
 496             },
 497             proc_macro_data,
 498             proc_macro_stability: if is_proc_macro {
 499                 tcx.lookup_stability(DefId::local(CRATE_DEF_INDEX)).map(|stab| stab.clone())
 500             } else {
 501                 None
 502             },
 503             compiler_builtins: attr::contains_name(&attrs, sym::compiler_builtins),
 504             needs_allocator: attr::contains_name(&attrs, sym::needs_allocator),
 505             needs_panic_runtime: attr::contains_name(&attrs, sym::needs_panic_runtime),
 506             no_builtins: attr::contains_name(&attrs, sym::no_builtins),
 507             panic_runtime: attr::contains_name(&attrs, sym::panic_runtime),
 508             profiler_runtime: attr::contains_name(&attrs, sym::profiler_runtime),
 509             sanitizer_runtime: attr::contains_name(&attrs, sym::sanitizer_runtime),
 510             symbol_mangling_version: tcx.sess.opts.debugging_opts.symbol_mangling_version,
 511
 512             crate_deps,
 513             dylib_dependency_formats,
 514             lib_features,
 515             lang_items,
 516             lang_items_missing,
 517             native_libraries,
 518             foreign_modules,
 519             source_map,
 520             def_path_table,
 521             impls,
 522             exported_symbols,
 523             interpret_alloc_index,
 524             entries_index,
 525         });
 526
 527         let total_bytes = self.position();
 528
 529         if self.tcx.sess.meta_stats() {
 530             let mut zero_bytes = 0;
 531             for e in self.opaque.data.iter() {
 532                 if *e == 0 {
 533                     zero_bytes += 1;
 534                 }
 535             }
 536
 537             println!("metadata stats:");
 538             println!("             dep bytes: {}", dep_bytes);
 539             println!("     lib feature bytes: {}", lib_feature_bytes);
 540             println!("       lang item bytes: {}", lang_item_bytes);
 541             println!("          native bytes: {}", native_lib_bytes);
 542             println!("         source_map bytes: {}", source_map_bytes);
 543             println!("            impl bytes: {}", impl_bytes);
 544             println!("    exp. symbols bytes: {}", exported_symbols_bytes);
 545             println!("  def-path table bytes: {}", def_path_table_bytes);
 546             println!(" proc-macro-data-bytes: {}", proc_macro_data_bytes);
 547             println!("            item bytes: {}", item_bytes);
 548             println!("   entries index bytes: {}", entries_index_bytes);
 549             println!("            zero bytes: {}", zero_bytes);
 550             println!("           total bytes: {}", total_bytes);
 551         }
 552
 553         root
 554     }
 555 }
 556
 557 impl EncodeContext<'tcx> {
 558     fn encode_variances_of(&mut self, def_id: DefId) -> LazySeq<ty::Variance> {
 559         debug!("EncodeContext::encode_variances_of({:?})", def_id);
 560         let tcx = self.tcx;
 561         self.lazy_seq_ref(&tcx.variances_of(def_id)[..])
 562     }
 563
 564     fn encode_item_type(&mut self, def_id: DefId) -> Lazy<Ty<'tcx>> {
 565         let tcx = self.tcx;
 566         let ty = tcx.type_of(def_id);
 567         debug!("EncodeContext::encode_item_type({:?}) => {:?}", def_id, ty);
 568         self.lazy(&ty)
 569     }
 570
 571     fn encode_enum_variant_info(
 572         &mut self,
 573         (enum_did, index): (DefId, VariantIdx),
 574     ) -> Entry<'tcx> {
 575         let tcx = self.tcx;
 576         let def = tcx.adt_def(enum_did);
 577         let variant = &def.variants[index];
 578         let def_id = variant.def_id;
 579         debug!("EncodeContext::encode_enum_variant_info({:?})", def_id);
 580
 581         let data = VariantData {
 582             ctor_kind: variant.ctor_kind,
 583             discr: variant.discr,
 584             // FIXME(eddyb) deduplicate these with `encode_enum_variant_ctor`.
 585             ctor: variant.ctor_def_id.map(|did| did.index),
 586             ctor_sig: if variant.ctor_kind == CtorKind::Fn {
 587                 variant.ctor_def_id.map(|ctor_def_id| self.lazy(&tcx.fn_sig(ctor_def_id)))
 588             } else {
 589                 None
 590             },
 591         };
 592
 593         let enum_id = tcx.hir().as_local_hir_id(enum_did).unwrap();
 594         let enum_vis = &tcx.hir().expect_item(enum_id).vis;
 595
 596         Entry {
 597             kind: EntryKind::Variant(self.lazy(&data)),
 598             visibility: self.lazy(&ty::Visibility::from_hir(enum_vis, enum_id, tcx)),
 599             span: self.lazy(&tcx.def_span(def_id)),
 600             attributes: self.encode_attributes(&tcx.get_attrs(def_id)),
 601             children: self.lazy_seq(variant.fields.iter().map(|f| {
 602                 assert!(f.did.is_local());
 603                 f.did.index
 604             })),
 605             stability: self.encode_stability(def_id),
 606             deprecation: self.encode_deprecation(def_id),
 607
 608             ty: Some(self.encode_item_type(def_id)),
 609             inherent_impls: LazySeq::empty(),
 610             variances: if variant.ctor_kind == CtorKind::Fn {
 611                 self.encode_variances_of(def_id)
 612             } else {
 613                 LazySeq::empty()
 614             },
 615             generics: Some(self.encode_generics(def_id)),
 616             predicates: Some(self.encode_predicates(def_id)),
 617             predicates_defined_on: None,
 618
 619             mir: self.encode_optimized_mir(def_id),
 620         }
 621     }
 622
 623     fn encode_enum_variant_ctor(
 624         &mut self,
 625         (enum_did, index): (DefId, VariantIdx),
 626     ) -> Entry<'tcx> {
 627         let tcx = self.tcx;
 628         let def = tcx.adt_def(enum_did);
 629         let variant = &def.variants[index];
 630         let def_id = variant.ctor_def_id.unwrap();
 631         debug!("EncodeContext::encode_enum_variant_ctor({:?})", def_id);
 632
 633         let data = VariantData {
 634             ctor_kind: variant.ctor_kind,
 635             discr: variant.discr,
 636             ctor: Some(def_id.index),
 637             ctor_sig: if variant.ctor_kind == CtorKind::Fn {
 638                 Some(self.lazy(&tcx.fn_sig(def_id)))
 639             } else {
 640                 None
 641             }
 642         };
 643
 644         // Variant constructors have the same visibility as the parent enums, unless marked as
 645         // non-exhaustive, in which case they are lowered to `pub(crate)`.
 646         let enum_id = tcx.hir().as_local_hir_id(enum_did).unwrap();
 647         let enum_vis = &tcx.hir().expect_item(enum_id).vis;
 648         let mut ctor_vis = ty::Visibility::from_hir(enum_vis, enum_id, tcx);
 649         if variant.is_field_list_non_exhaustive() && ctor_vis == ty::Visibility::Public {
 650             ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 651         }
 652
 653         Entry {
 654             kind: EntryKind::Variant(self.lazy(&data)),
 655             visibility: self.lazy(&ctor_vis),
 656             span: self.lazy(&tcx.def_span(def_id)),
 657             attributes: LazySeq::empty(),
 658             children: LazySeq::empty(),
 659             stability: self.encode_stability(def_id),
 660             deprecation: self.encode_deprecation(def_id),
 661
 662             ty: Some(self.encode_item_type(def_id)),
 663             inherent_impls: LazySeq::empty(),
 664             variances: if variant.ctor_kind == CtorKind::Fn {
 665                 self.encode_variances_of(def_id)
 666             } else {
 667                 LazySeq::empty()
 668             },
 669             generics: Some(self.encode_generics(def_id)),
 670             predicates: Some(self.encode_predicates(def_id)),
 671             predicates_defined_on: None,
 672
 673             mir: self.encode_optimized_mir(def_id),
 674         }
 675     }
 676
 677     fn encode_info_for_mod(
 678         &mut self,
 679         (id, md, attrs, vis): (hir::HirId, &hir::Mod, &[ast::Attribute], &hir::Visibility),
 680     ) -> Entry<'tcx> {
 681         let tcx = self.tcx;
 682         let def_id = tcx.hir().local_def_id(id);
 683         debug!("EncodeContext::encode_info_for_mod({:?})", def_id);
 684
 685         let data = ModData {
 686             reexports: match tcx.module_exports(def_id) {
 687                 Some(exports) => self.lazy_seq_ref(exports),
 688                 _ => LazySeq::empty(),
 689             },
 690         };
 691
 692         Entry {
 693             kind: EntryKind::Mod(self.lazy(&data)),
 694             visibility: self.lazy(&ty::Visibility::from_hir(vis, id, tcx)),
 695             span: self.lazy(&tcx.def_span(def_id)),
 696             attributes: self.encode_attributes(attrs),
 697             children: self.lazy_seq(md.item_ids.iter().map(|item_id| {
 698                 tcx.hir().local_def_id(item_id.id).index
 699             })),
 700             stability: self.encode_stability(def_id),
 701             deprecation: self.encode_deprecation(def_id),
 702
 703             ty: None,
 704             inherent_impls: LazySeq::empty(),
 705             variances: LazySeq::empty(),
 706             generics: None,
 707             predicates: None,
 708             predicates_defined_on: None,
 709
 710             mir: None
 711         }
 712     }
 713
 714     fn encode_field(
 715         &mut self,
 716         (adt_def_id, variant_index, field_index): (DefId, VariantIdx, usize),
 717     ) -> Entry<'tcx> {
 718         let tcx = self.tcx;
 719         let variant = &tcx.adt_def(adt_def_id).variants[variant_index];
 720         let field = &variant.fields[field_index];
 721
 722         let def_id = field.did;
 723         debug!("EncodeContext::encode_field({:?})", def_id);
 724
 725         let variant_id = tcx.hir().as_local_hir_id(variant.def_id).unwrap();
 726         let variant_data = tcx.hir().expect_variant_data(variant_id);
 727
 728         Entry {
 729             kind: EntryKind::Field,
 730             visibility: self.lazy(&field.vis),
 731             span: self.lazy(&tcx.def_span(def_id)),
 732             attributes: self.encode_attributes(&variant_data.fields()[field_index].attrs),
 733             children: LazySeq::empty(),
 734             stability: self.encode_stability(def_id),
 735             deprecation: self.encode_deprecation(def_id),
 736
 737             ty: Some(self.encode_item_type(def_id)),
 738             inherent_impls: LazySeq::empty(),
 739             variances: LazySeq::empty(),
 740             generics: Some(self.encode_generics(def_id)),
 741             predicates: Some(self.encode_predicates(def_id)),
 742             predicates_defined_on: None,
 743
 744             mir: None,
 745         }
 746     }
 747
 748     fn encode_struct_ctor(&mut self, (adt_def_id, def_id): (DefId, DefId)) -> Entry<'tcx> {
 749         debug!("EncodeContext::encode_struct_ctor({:?})", def_id);
 750         let tcx = self.tcx;
 751         let adt_def = tcx.adt_def(adt_def_id);
 752         let variant = adt_def.non_enum_variant();
 753
 754         let data = VariantData {
 755             ctor_kind: variant.ctor_kind,
 756             discr: variant.discr,
 757             ctor: Some(def_id.index),
 758             ctor_sig: if variant.ctor_kind == CtorKind::Fn {
 759                 Some(self.lazy(&tcx.fn_sig(def_id)))
 760             } else {
 761                 None
 762             }
 763         };
 764
 765         let struct_id = tcx.hir().as_local_hir_id(adt_def_id).unwrap();
 766         let struct_vis = &tcx.hir().expect_item(struct_id).vis;
 767         let mut ctor_vis = ty::Visibility::from_hir(struct_vis, struct_id, tcx);
 768         for field in &variant.fields {
 769             if ctor_vis.is_at_least(field.vis, tcx) {
 770                 ctor_vis = field.vis;
 771             }
 772         }
 773
 774         // If the structure is marked as non_exhaustive then lower the visibility
 775         // to within the crate.
 776         if adt_def.non_enum_variant().is_field_list_non_exhaustive() &&
 777             ctor_vis == ty::Visibility::Public
 778         {
 779             ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
 780         }
 781
 782         let repr_options = get_repr_options(tcx, adt_def_id);
 783
 784         Entry {
 785             kind: EntryKind::Struct(self.lazy(&data), repr_options),
 786             visibility: self.lazy(&ctor_vis),
 787             span: self.lazy(&tcx.def_span(def_id)),
 788             attributes: LazySeq::empty(),
 789             children: LazySeq::empty(),
 790             stability: self.encode_stability(def_id),
 791             deprecation: self.encode_deprecation(def_id),
 792
 793             ty: Some(self.encode_item_type(def_id)),
 794             inherent_impls: LazySeq::empty(),
 795             variances: if variant.ctor_kind == CtorKind::Fn {
 796                 self.encode_variances_of(def_id)
 797             } else {
 798                 LazySeq::empty()
 799             },
 800             generics: Some(self.encode_generics(def_id)),
 801             predicates: Some(self.encode_predicates(def_id)),
 802             predicates_defined_on: None,
 803
 804             mir: self.encode_optimized_mir(def_id),
 805         }
 806     }
 807
 808     fn encode_generics(&mut self, def_id: DefId) -> Lazy<ty::Generics> {
 809         debug!("EncodeContext::encode_generics({:?})", def_id);
 810         let tcx = self.tcx;
 811         self.lazy(tcx.generics_of(def_id))
 812     }
 813
 814     fn encode_predicates(&mut self, def_id: DefId) -> Lazy<ty::GenericPredicates<'tcx>> {
 815         debug!("EncodeContext::encode_predicates({:?})", def_id);
 816         let tcx = self.tcx;
 817         self.lazy(&tcx.predicates_of(def_id))
 818     }
 819
 820     fn encode_predicates_defined_on(&mut self, def_id: DefId) -> Lazy<ty::GenericPredicates<'tcx>> {
 821         debug!("EncodeContext::encode_predicates_defined_on({:?})", def_id);
 822         let tcx = self.tcx;
 823         self.lazy(&tcx.predicates_defined_on(def_id))
 824     }
 825
 826     fn encode_info_for_trait_item(&mut self, def_id: DefId) -> Entry<'tcx> {
 827         debug!("EncodeContext::encode_info_for_trait_item({:?})", def_id);
 828         let tcx = self.tcx;
 829
 830         let hir_id = tcx.hir().as_local_hir_id(def_id).unwrap();
 831         let ast_item = tcx.hir().expect_trait_item(hir_id);
 832         let trait_item = tcx.associated_item(def_id);
 833
 834         let container = match trait_item.defaultness {
 835             hir::Defaultness::Default { has_value: true } =>
 836                 AssocContainer::TraitWithDefault,
 837             hir::Defaultness::Default { has_value: false } =>
 838                 AssocContainer::TraitRequired,
 839             hir::Defaultness::Final =>
 840                 span_bug!(ast_item.span, "traits cannot have final items"),
 841         };
 842
 843         let kind = match trait_item.kind {
 844             ty::AssocKind::Const => {
 845                 let const_qualif =
 846                     if let hir::TraitItemKind::Const(_, Some(body)) = ast_item.node {
 847                         self.const_qualif(0, body)
 848                     } else {
 849                         ConstQualif { mir: 0, ast_promotable: false }
 850                     };
 851
 852                 let rendered =
 853                     hir::print::to_string(self.tcx.hir(), |s| s.print_trait_item(ast_item));
 854                 let rendered_const = self.lazy(&RenderedConst(rendered));
 855
 856                 EntryKind::AssocConst(container, const_qualif, rendered_const)
 857             }
 858             ty::AssocKind::Method => {
 859                 let fn_data = if let hir::TraitItemKind::Method(_, ref m) = ast_item.node {
 860                     let arg_names = match *m {
 861                         hir::TraitMethod::Required(ref names) => {
 862                             self.encode_fn_arg_names(names)
 863                         }
 864                         hir::TraitMethod::Provided(body) => {
 865                             self.encode_fn_arg_names_for_body(body)
 866                         }
 867                     };
 868                     FnData {
 869                         constness: hir::Constness::NotConst,
 870                         arg_names,
 871                         sig: self.lazy(&tcx.fn_sig(def_id)),
 872                     }
 873                 } else {
 874                     bug!()
 875                 };
 876                 EntryKind::Method(self.lazy(&MethodData {
 877                     fn_data,
 878                     container,
 879                     has_self: trait_item.method_has_self_argument,
 880                 }))
 881             }
 882             ty::AssocKind::Type => EntryKind::AssocType(container),
 883             ty::AssocKind::OpaqueTy => span_bug!(ast_item.span, "opaque type in trait"),
 884         };
 885
 886         Entry {
 887             kind,
 888             visibility: self.lazy(&trait_item.vis),
 889             span: self.lazy(&ast_item.span),
 890             attributes: self.encode_attributes(&ast_item.attrs),
 891             children: LazySeq::empty(),
 892             stability: self.encode_stability(def_id),
 893             deprecation: self.encode_deprecation(def_id),
 894
 895             ty: match trait_item.kind {
 896                 ty::AssocKind::Const |
 897                 ty::AssocKind::Method => {
 898                     Some(self.encode_item_type(def_id))
 899                 }
 900                 ty::AssocKind::Type => {
 901                     if trait_item.defaultness.has_value() {
 902                         Some(self.encode_item_type(def_id))
 903                     } else {
 904                         None
 905                     }
 906                 }
 907                 ty::AssocKind::OpaqueTy => unreachable!(),
 908             },
 909             inherent_impls: LazySeq::empty(),
 910             variances: if trait_item.kind == ty::AssocKind::Method {
 911                 self.encode_variances_of(def_id)
 912             } else {
 913                 LazySeq::empty()
 914             },
 915             generics: Some(self.encode_generics(def_id)),
 916             predicates: Some(self.encode_predicates(def_id)),
 917             predicates_defined_on: None,
 918
 919             mir: self.encode_optimized_mir(def_id),
 920         }
 921     }
 922
 923     fn metadata_output_only(&self) -> bool {
 924         // MIR optimisation can be skipped when we're just interested in the metadata.
 925         !self.tcx.sess.opts.output_types.should_codegen()
 926     }
 927
 928     fn const_qualif(&self, mir: u8, body_id: hir::BodyId) -> ConstQualif {
 929         let body_owner_def_id = self.tcx.hir().body_owner_def_id(body_id);
 930         let ast_promotable = self.tcx.const_is_rvalue_promotable_to_static(body_owner_def_id);
 931
 932         ConstQualif { mir, ast_promotable }
 933     }
 934
 935     fn encode_info_for_impl_item(&mut self, def_id: DefId) -> Entry<'tcx> {
 936         debug!("EncodeContext::encode_info_for_impl_item({:?})", def_id);
 937         let tcx = self.tcx;
 938
 939         let hir_id = self.tcx.hir().as_local_hir_id(def_id).unwrap();
 940         let ast_item = self.tcx.hir().expect_impl_item(hir_id);
 941         let impl_item = self.tcx.associated_item(def_id);
 942
 943         let container = match impl_item.defaultness {
 944             hir::Defaultness::Default { has_value: true } => AssocContainer::ImplDefault,
 945             hir::Defaultness::Final => AssocContainer::ImplFinal,
 946             hir::Defaultness::Default { has_value: false } =>
 947                 span_bug!(ast_item.span, "impl items always have values (currently)"),
 948         };
 949
 950         let kind = match impl_item.kind {
 951             ty::AssocKind::Const => {
 952                 if let hir::ImplItemKind::Const(_, body_id) = ast_item.node {
 953                     let mir = self.tcx.at(ast_item.span).mir_const_qualif(def_id).0;
 954
 955                     EntryKind::AssocConst(container,
 956                         self.const_qualif(mir, body_id),
 957                         self.encode_rendered_const_for_body(body_id))
 958                 } else {
 959                     bug!()
 960                 }
 961             }
 962             ty::AssocKind::Method => {
 963                 let fn_data = if let hir::ImplItemKind::Method(ref sig, body) = ast_item.node {
 964                     FnData {
 965                         constness: sig.header.constness,
 966                         arg_names: self.encode_fn_arg_names_for_body(body),
 967                         sig: self.lazy(&tcx.fn_sig(def_id)),
 968                     }
 969                 } else {
 970                     bug!()
 971                 };
 972                 EntryKind::Method(self.lazy(&MethodData {
 973                     fn_data,
 974                     container,
 975                     has_self: impl_item.method_has_self_argument,
 976                 }))
 977             }
 978             ty::AssocKind::OpaqueTy => EntryKind::AssocOpaqueTy(container),
 979             ty::AssocKind::Type => EntryKind::AssocType(container)
 980         };
 981
 982         let mir =
 983             match ast_item.node {
 984                 hir::ImplItemKind::Const(..) => true,
 985                 hir::ImplItemKind::Method(ref sig, _) => {
 986                     let generics = self.tcx.generics_of(def_id);
 987                     let needs_inline = (generics.requires_monomorphization(self.tcx) ||
 988                                         tcx.codegen_fn_attrs(def_id).requests_inline()) &&
 989                                         !self.metadata_output_only();
 990                     let is_const_fn = sig.header.constness == hir::Constness::Const;
 991                     let always_encode_mir = self.tcx.sess.opts.debugging_opts.always_encode_mir;
 992                     needs_inline || is_const_fn || always_encode_mir
 993                 },
 994                 hir::ImplItemKind::OpaqueTy(..) |
 995                 hir::ImplItemKind::TyAlias(..) => false,
 996             };
 997
 998         Entry {
 999             kind,
1000             visibility: self.lazy(&impl_item.vis),
1001             span: self.lazy(&ast_item.span),
1002             attributes: self.encode_attributes(&ast_item.attrs),
1003             children: LazySeq::empty(),
1004             stability: self.encode_stability(def_id),
1005             deprecation: self.encode_deprecation(def_id),
1006
1007             ty: Some(self.encode_item_type(def_id)),
1008             inherent_impls: LazySeq::empty(),
1009             variances: if impl_item.kind == ty::AssocKind::Method {
1010                 self.encode_variances_of(def_id)
1011             } else {
1012                 LazySeq::empty()
1013             },
1014             generics: Some(self.encode_generics(def_id)),
1015             predicates: Some(self.encode_predicates(def_id)),
1016             predicates_defined_on: None,
1017
1018             mir: if mir { self.encode_optimized_mir(def_id) } else { None },
1019         }
1020     }
1021
1022     fn encode_fn_arg_names_for_body(&mut self, body_id: hir::BodyId)
1023                                     -> LazySeq<ast::Name> {
1024         self.tcx.dep_graph.with_ignore(|| {
1025             let body = self.tcx.hir().body(body_id);
1026             self.lazy_seq(body.arguments.iter().map(|arg| {
1027                 match arg.pat.node {
1028                     PatKind::Binding(_, _, ident, _) => ident.name,
1029                     _ => kw::Invalid,
1030                 }
1031             }))
1032         })
1033     }
1034
1035     fn encode_fn_arg_names(&mut self, param_names: &[ast::Ident]) -> LazySeq<ast::Name> {
1036         self.lazy_seq(param_names.iter().map(|ident| ident.name))
1037     }
1038
1039     fn encode_optimized_mir(&mut self, def_id: DefId) -> Option<Lazy<mir::Body<'tcx>>> {
1040         debug!("EntryBuilder::encode_mir({:?})", def_id);
1041         if self.tcx.mir_keys(LOCAL_CRATE).contains(&def_id) {
1042             let mir = self.tcx.optimized_mir(def_id);
1043             Some(self.lazy(&mir))
1044         } else {
1045             None
1046         }
1047     }
1048
1049     // Encodes the inherent implementations of a structure, enumeration, or trait.
1050     fn encode_inherent_implementations(&mut self, def_id: DefId) -> LazySeq<DefIndex> {
1051         debug!("EncodeContext::encode_inherent_implementations({:?})", def_id);
1052         let implementations = self.tcx.inherent_impls(def_id);
1053         if implementations.is_empty() {
1054             LazySeq::empty()
1055         } else {
1056             self.lazy_seq(implementations.iter().map(|&def_id| {
1057                 assert!(def_id.is_local());
1058                 def_id.index
1059             }))
1060         }
1061     }
1062
1063     fn encode_stability(&mut self, def_id: DefId) -> Option<Lazy<attr::Stability>> {
1064         debug!("EncodeContext::encode_stability({:?})", def_id);
1065         self.tcx.lookup_stability(def_id).map(|stab| self.lazy(stab))
1066     }
1067
1068     fn encode_deprecation(&mut self, def_id: DefId) -> Option<Lazy<attr::Deprecation>> {
1069         debug!("EncodeContext::encode_deprecation({:?})", def_id);
1070         self.tcx.lookup_deprecation(def_id).map(|depr| self.lazy(&depr))
1071     }
1072
1073     fn encode_rendered_const_for_body(&mut self, body_id: hir::BodyId) -> Lazy<RenderedConst> {
1074         let body = self.tcx.hir().body(body_id);
1075         let rendered = hir::print::to_string(self.tcx.hir(), |s| s.print_expr(&body.value));
1076         let rendered_const = &RenderedConst(rendered);
1077         self.lazy(rendered_const)
1078     }
1079
1080     fn encode_info_for_item(&mut self, (def_id, item): (DefId, &'tcx hir::Item)) -> Entry<'tcx> {
1081         let tcx = self.tcx;
1082
1083         debug!("EncodeContext::encode_info_for_item({:?})", def_id);
1084
1085         let kind = match item.node {
1086             hir::ItemKind::Static(_, hir::MutMutable, _) => EntryKind::MutStatic,
1087             hir::ItemKind::Static(_, hir::MutImmutable, _) => EntryKind::ImmStatic,
1088             hir::ItemKind::Const(_, body_id) => {
1089                 let mir = tcx.at(item.span).mir_const_qualif(def_id).0;
1090                 EntryKind::Const(
1091                     self.const_qualif(mir, body_id),
1092                     self.encode_rendered_const_for_body(body_id)
1093                 )
1094             }
1095             hir::ItemKind::Fn(_, header, .., body) => {
1096                 let data = FnData {
1097                     constness: header.constness,
1098                     arg_names: self.encode_fn_arg_names_for_body(body),
1099                     sig: self.lazy(&tcx.fn_sig(def_id)),
1100                 };
1101
1102                 EntryKind::Fn(self.lazy(&data))
1103             }
1104             hir::ItemKind::Mod(ref m) => {
1105                 return self.encode_info_for_mod((item.hir_id, m, &item.attrs, &item.vis));
1106             }
1107             hir::ItemKind::ForeignMod(_) => EntryKind::ForeignMod,
1108             hir::ItemKind::GlobalAsm(..) => EntryKind::GlobalAsm,
1109             hir::ItemKind::TyAlias(..) => EntryKind::Type,
1110             hir::ItemKind::OpaqueTy(..) => EntryKind::OpaqueTy,
1111             hir::ItemKind::Enum(..) => EntryKind::Enum(get_repr_options(tcx, def_id)),
1112             hir::ItemKind::Struct(ref struct_def, _) => {
1113                 let variant = tcx.adt_def(def_id).non_enum_variant();
1114
1115                 // Encode def_ids for each field and method
1116                 // for methods, write all the stuff get_trait_method
1117                 // needs to know
1118                 let ctor = struct_def.ctor_hir_id()
1119                     .map(|ctor_hir_id| tcx.hir().local_def_id(ctor_hir_id).index);
1120
1121                 let repr_options = get_repr_options(tcx, def_id);
1122
1123                 EntryKind::Struct(self.lazy(&VariantData {
1124                     ctor_kind: variant.ctor_kind,
1125                     discr: variant.discr,
1126                     ctor,
1127                     ctor_sig: None,
1128                 }), repr_options)
1129             }
1130             hir::ItemKind::Union(..) => {
1131                 let variant = tcx.adt_def(def_id).non_enum_variant();
1132                 let repr_options = get_repr_options(tcx, def_id);
1133
1134                 EntryKind::Union(self.lazy(&VariantData {
1135                     ctor_kind: variant.ctor_kind,
1136                     discr: variant.discr,
1137                     ctor: None,
1138                     ctor_sig: None,
1139                 }), repr_options)
1140             }
1141             hir::ItemKind::Impl(_, polarity, defaultness, ..) => {
1142                 let trait_ref = tcx.impl_trait_ref(def_id);
1143                 let parent = if let Some(trait_ref) = trait_ref {
1144                     let trait_def = tcx.trait_def(trait_ref.def_id);
1145                     trait_def.ancestors(tcx, def_id).nth(1).and_then(|node| {
1146                         match node {
1147                             specialization_graph::Node::Impl(parent) => Some(parent),
1148                             _ => None,
1149                         }
1150                     })
1151                 } else {
1152                     None
1153                 };
1154
1155                 // if this is an impl of `CoerceUnsized`, create its
1156                 // "unsized info", else just store None
1157                 let coerce_unsized_info =
1158                     trait_ref.and_then(|t| {
1159                         if Some(t.def_id) == tcx.lang_items().coerce_unsized_trait() {
1160                             Some(tcx.at(item.span).coerce_unsized_info(def_id))
1161                         } else {
1162                             None
1163                         }
1164                     });
1165
1166                 let data = ImplData {
1167                     polarity,
1168                     defaultness,
1169                     parent_impl: parent,
1170                     coerce_unsized_info,
1171                     trait_ref: trait_ref.map(|trait_ref| self.lazy(&trait_ref)),
1172                 };
1173
1174                 EntryKind::Impl(self.lazy(&data))
1175             }
1176             hir::ItemKind::Trait(..) => {
1177                 let trait_def = tcx.trait_def(def_id);
1178                 let data = TraitData {
1179                     unsafety: trait_def.unsafety,
1180                     paren_sugar: trait_def.paren_sugar,
1181                     has_auto_impl: tcx.trait_is_auto(def_id),
1182                     is_marker: trait_def.is_marker,
1183                     super_predicates: self.lazy(&tcx.super_predicates_of(def_id)),
1184                 };
1185
1186                 EntryKind::Trait(self.lazy(&data))
1187             }
1188             hir::ItemKind::TraitAlias(..) => {
1189                 let data = TraitAliasData {
1190                     super_predicates: self.lazy(&tcx.super_predicates_of(def_id)),
1191                 };
1192
1193                 EntryKind::TraitAlias(self.lazy(&data))
1194             }
1195             hir::ItemKind::ExternCrate(_) |
1196             hir::ItemKind::Use(..) => bug!("cannot encode info for item {:?}", item),
1197         };
1198
1199         Entry {
1200             kind,
1201             visibility: self.lazy(&ty::Visibility::from_hir(&item.vis, item.hir_id, tcx)),
1202             span: self.lazy(&item.span),
1203             attributes: self.encode_attributes(&item.attrs),
1204             children: match item.node {
1205                 hir::ItemKind::ForeignMod(ref fm) => {
1206                     self.lazy_seq(fm.items
1207                         .iter()
1208                         .map(|foreign_item| tcx.hir().local_def_id(
1209                             foreign_item.hir_id).index))
1210                 }
1211                 hir::ItemKind::Enum(..) => {
1212                     let def = self.tcx.adt_def(def_id);
1213                     self.lazy_seq(def.variants.iter().map(|v| {
1214                         assert!(v.def_id.is_local());
1215                         v.def_id.index
1216                     }))
1217                 }
1218                 hir::ItemKind::Struct(..) |
1219                 hir::ItemKind::Union(..) => {
1220                     let def = self.tcx.adt_def(def_id);
1221                     self.lazy_seq(def.non_enum_variant().fields.iter().map(|f| {
1222                         assert!(f.did.is_local());
1223                         f.did.index
1224                     }))
1225                 }
1226                 hir::ItemKind::Impl(..) |
1227                 hir::ItemKind::Trait(..) => {
1228                     self.lazy_seq(tcx.associated_item_def_ids(def_id).iter().map(|&def_id| {
1229                         assert!(def_id.is_local());
1230                         def_id.index
1231                     }))
1232                 }
1233                 _ => LazySeq::empty(),
1234             },
1235             stability: self.encode_stability(def_id),
1236             deprecation: self.encode_deprecation(def_id),
1237
1238             ty: match item.node {
1239                 hir::ItemKind::Static(..) |
1240                 hir::ItemKind::Const(..) |
1241                 hir::ItemKind::Fn(..) |
1242                 hir::ItemKind::TyAlias(..) |
1243                 hir::ItemKind::OpaqueTy(..) |
1244                 hir::ItemKind::Enum(..) |
1245                 hir::ItemKind::Struct(..) |
1246                 hir::ItemKind::Union(..) |
1247                 hir::ItemKind::Impl(..) => Some(self.encode_item_type(def_id)),
1248                 _ => None,
1249             },
1250             inherent_impls: self.encode_inherent_implementations(def_id),
1251             variances: match item.node {
1252                 hir::ItemKind::Enum(..) |
1253                 hir::ItemKind::Struct(..) |
1254                 hir::ItemKind::Union(..) |
1255                 hir::ItemKind::Fn(..) => self.encode_variances_of(def_id),
1256                 _ => LazySeq::empty(),
1257             },
1258             generics: match item.node {
1259                 hir::ItemKind::Static(..) |
1260                 hir::ItemKind::Const(..) |
1261                 hir::ItemKind::Fn(..) |
1262                 hir::ItemKind::TyAlias(..) |
1263                 hir::ItemKind::Enum(..) |
1264                 hir::ItemKind::Struct(..) |
1265                 hir::ItemKind::Union(..) |
1266                 hir::ItemKind::Impl(..) |
1267                 hir::ItemKind::OpaqueTy(..) |
1268                 hir::ItemKind::Trait(..) => Some(self.encode_generics(def_id)),
1269                 hir::ItemKind::TraitAlias(..) => Some(self.encode_generics(def_id)),
1270                 _ => None,
1271             },
1272             predicates: match item.node {
1273                 hir::ItemKind::Static(..) |
1274                 hir::ItemKind::Const(..) |
1275                 hir::ItemKind::Fn(..) |
1276                 hir::ItemKind::TyAlias(..) |
1277                 hir::ItemKind::Enum(..) |
1278                 hir::ItemKind::Struct(..) |
1279                 hir::ItemKind::Union(..) |
1280                 hir::ItemKind::Impl(..) |
1281                 hir::ItemKind::OpaqueTy(..) |
1282                 hir::ItemKind::Trait(..) |
1283                 hir::ItemKind::TraitAlias(..) => Some(self.encode_predicates(def_id)),
1284                 _ => None,
1285             },
1286
1287             // The only time that `predicates_defined_on` is used (on
1288             // an external item) is for traits, during chalk lowering,
1289             // so only encode it in that case as an efficiency
1290             // hack. (No reason not to expand it in the future if
1291             // necessary.)
1292             predicates_defined_on: match item.node {
1293                 hir::ItemKind::Trait(..) |
1294                 hir::ItemKind::TraitAlias(..) => Some(self.encode_predicates_defined_on(def_id)),
1295                 _ => None, // not *wrong* for other kinds of items, but not needed
1296             },
1297
1298             mir: match item.node {
1299                 hir::ItemKind::Static(..) => {
1300                     self.encode_optimized_mir(def_id)
1301                 }
1302                 hir::ItemKind::Const(..) => self.encode_optimized_mir(def_id),
1303                 hir::ItemKind::Fn(_, header, ..) => {
1304                     let generics = tcx.generics_of(def_id);
1305                     let needs_inline =
1306                         (generics.requires_monomorphization(tcx) ||
1307                          tcx.codegen_fn_attrs(def_id).requests_inline()) &&
1308                             !self.metadata_output_only();
1309                     let always_encode_mir = self.tcx.sess.opts.debugging_opts.always_encode_mir;
1310                     if needs_inline
1311                         || header.constness == hir::Constness::Const
1312                         || always_encode_mir
1313                     {
1314                         self.encode_optimized_mir(def_id)
1315                     } else {
1316                         None
1317                     }
1318                 }
1319                 _ => None,
1320             },
1321         }
1322     }
1323
1324     /// Serialize the text of exported macros
1325     fn encode_info_for_macro_def(&mut self, macro_def: &hir::MacroDef) -> Entry<'tcx> {
1326         use syntax::print::pprust;
1327         let def_id = self.tcx.hir().local_def_id(macro_def.hir_id);
1328         Entry {
1329             kind: EntryKind::MacroDef(self.lazy(&MacroDef {
1330                 body: pprust::tokens_to_string(macro_def.body.clone()),
1331                 legacy: macro_def.legacy,
1332             })),
1333             visibility: self.lazy(&ty::Visibility::Public),
1334             span: self.lazy(&macro_def.span),
1335             attributes: self.encode_attributes(&macro_def.attrs),
1336             stability: self.encode_stability(def_id),
1337             deprecation: self.encode_deprecation(def_id),
1338
1339             children: LazySeq::empty(),
1340             ty: None,
1341             inherent_impls: LazySeq::empty(),
1342             variances: LazySeq::empty(),
1343             generics: None,
1344             predicates: None,
1345             predicates_defined_on: None,
1346             mir: None,
1347         }
1348     }
1349
1350     fn encode_info_for_generic_param(
1351         &mut self,
1352         def_id: DefId,
1353         entry_kind: EntryKind<'tcx>,
1354         encode_type: bool,
1355     ) -> Entry<'tcx> {
1356         let tcx = self.tcx;
1357         Entry {
1358             kind: entry_kind,
1359             visibility: self.lazy(&ty::Visibility::Public),
1360             span: self.lazy(&tcx.def_span(def_id)),
1361             attributes: LazySeq::empty(),
1362             children: LazySeq::empty(),
1363             stability: None,
1364             deprecation: None,
1365             ty: if encode_type { Some(self.encode_item_type(def_id)) } else { None },
1366             inherent_impls: LazySeq::empty(),
1367             variances: LazySeq::empty(),
1368             generics: None,
1369             predicates: None,
1370             predicates_defined_on: None,
1371
1372             mir: None,
1373         }
1374     }
1375
1376     fn encode_info_for_ty_param(
1377         &mut self,
1378         (def_id, encode_type): (DefId, bool),
1379     ) -> Entry<'tcx> {
1380         debug!("EncodeContext::encode_info_for_ty_param({:?})", def_id);
1381         self.encode_info_for_generic_param(def_id, EntryKind::TypeParam, encode_type)
1382     }
1383
1384     fn encode_info_for_const_param(
1385         &mut self,
1386         def_id: DefId,
1387     ) -> Entry<'tcx> {
1388         debug!("EncodeContext::encode_info_for_const_param({:?})", def_id);
1389         self.encode_info_for_generic_param(def_id, EntryKind::ConstParam, true)
1390     }
1391
1392     fn encode_info_for_closure(&mut self, def_id: DefId) -> Entry<'tcx> {
1393         debug!("EncodeContext::encode_info_for_closure({:?})", def_id);
1394         let tcx = self.tcx;
1395
1396         let tables = self.tcx.typeck_tables_of(def_id);
1397         let hir_id = self.tcx.hir().as_local_hir_id(def_id).unwrap();
1398         let kind = match tables.node_type(hir_id).sty {
1399             ty::Generator(def_id, ..) => {
1400                 let layout = self.tcx.generator_layout(def_id);
1401                 let data = GeneratorData {
1402                     layout: layout.clone(),
1403                 };
1404                 EntryKind::Generator(self.lazy(&data))
1405             }
1406
1407             ty::Closure(def_id, substs) => {
1408                 let sig = substs.closure_sig(def_id, self.tcx);
1409                 let data = ClosureData { sig: self.lazy(&sig) };
1410                 EntryKind::Closure(self.lazy(&data))
1411             }
1412
1413             _ => bug!("closure that is neither generator nor closure")
1414         };
1415
1416         Entry {
1417             kind,
1418             visibility: self.lazy(&ty::Visibility::Public),
1419             span: self.lazy(&tcx.def_span(def_id)),
1420             attributes: self.encode_attributes(&tcx.get_attrs(def_id)),
1421             children: LazySeq::empty(),
1422             stability: None,
1423             deprecation: None,
1424
1425             ty: Some(self.encode_item_type(def_id)),
1426             inherent_impls: LazySeq::empty(),
1427             variances: LazySeq::empty(),
1428             generics: Some(self.encode_generics(def_id)),
1429             predicates: None,
1430             predicates_defined_on: None,
1431
1432             mir: self.encode_optimized_mir(def_id),
1433         }
1434     }
1435
1436     fn encode_info_for_anon_const(&mut self, def_id: DefId) -> Entry<'tcx> {
1437         debug!("EncodeContext::encode_info_for_anon_const({:?})", def_id);
1438         let tcx = self.tcx;
1439         let id = tcx.hir().as_local_hir_id(def_id).unwrap();
1440         let body_id = tcx.hir().body_owned_by(id);
1441         let const_data = self.encode_rendered_const_for_body(body_id);
1442         let mir = tcx.mir_const_qualif(def_id).0;
1443
1444         Entry {
1445             kind: EntryKind::Const(self.const_qualif(mir, body_id), const_data),
1446             visibility: self.lazy(&ty::Visibility::Public),
1447             span: self.lazy(&tcx.def_span(def_id)),
1448             attributes: LazySeq::empty(),
1449             children: LazySeq::empty(),
1450             stability: None,
1451             deprecation: None,
1452
1453             ty: Some(self.encode_item_type(def_id)),
1454             inherent_impls: LazySeq::empty(),
1455             variances: LazySeq::empty(),
1456             generics: Some(self.encode_generics(def_id)),
1457             predicates: Some(self.encode_predicates(def_id)),
1458             predicates_defined_on: None,
1459
1460             mir: self.encode_optimized_mir(def_id),
1461         }
1462     }
1463
1464     fn encode_attributes(&mut self, attrs: &[ast::Attribute]) -> LazySeq<ast::Attribute> {
1465         self.lazy_seq_ref(attrs)
1466     }
1467
1468     fn encode_native_libraries(&mut self) -> LazySeq<NativeLibrary> {
1469         let used_libraries = self.tcx.native_libraries(LOCAL_CRATE);
1470         self.lazy_seq(used_libraries.iter().cloned())
1471     }
1472
1473     fn encode_foreign_modules(&mut self) -> LazySeq<ForeignModule> {
1474         let foreign_modules = self.tcx.foreign_modules(LOCAL_CRATE);
1475         self.lazy_seq(foreign_modules.iter().cloned())
1476     }
1477
1478     fn encode_proc_macros(&mut self) -> Option<LazySeq<DefIndex>> {
1479         let is_proc_macro = self.tcx.sess.crate_types.borrow().contains(&CrateType::ProcMacro);
1480         if is_proc_macro {
1481             let proc_macros: Vec<_> = self.tcx.hir().krate().items.values().filter_map(|item| {
1482                 if item.attrs.iter().any(|attr| is_proc_macro_attr(attr)) {
1483                     Some(item.hir_id.owner)
1484                 } else {
1485                     None
1486                 }
1487             }).collect();
1488             Some(self.lazy_seq(proc_macros))
1489         } else {
1490             None
1491         }
1492     }
1493
1494     fn encode_crate_deps(&mut self) -> LazySeq<CrateDep> {
1495         let crates = self.tcx.crates();
1496
1497         let mut deps = crates
1498             .iter()
1499             .map(|&cnum| {
1500                 let dep = CrateDep {
1501                     name: self.tcx.original_crate_name(cnum),
1502                     hash: self.tcx.crate_hash(cnum),
1503                     kind: self.tcx.dep_kind(cnum),
1504                     extra_filename: self.tcx.extra_filename(cnum),
1505                 };
1506                 (cnum, dep)
1507             })
1508             .collect::<Vec<_>>();
1509
1510         deps.sort_by_key(|&(cnum, _)| cnum);
1511
1512         {
1513             // Sanity-check the crate numbers
1514             let mut expected_cnum = 1;
1515             for &(n, _) in &deps {
1516                 assert_eq!(n, CrateNum::new(expected_cnum));
1517                 expected_cnum += 1;
1518             }
1519         }
1520
1521         // We're just going to write a list of crate 'name-hash-version's, with
1522         // the assumption that they are numbered 1 to n.
1523         // FIXME (#2166): This is not nearly enough to support correct versioning
1524         // but is enough to get transitive crate dependencies working.
1525         self.lazy_seq_ref(deps.iter().map(|&(_, ref dep)| dep))
1526     }
1527
1528     fn encode_lib_features(&mut self) -> LazySeq<(ast::Name, Option<ast::Name>)> {
1529         let tcx = self.tcx;
1530         let lib_features = tcx.lib_features();
1531         self.lazy_seq(lib_features.to_vec())
1532     }
1533
1534     fn encode_lang_items(&mut self) -> LazySeq<(DefIndex, usize)> {
1535         let tcx = self.tcx;
1536         let lang_items = tcx.lang_items();
1537         let lang_items = lang_items.items().iter();
1538         self.lazy_seq(lang_items.enumerate().filter_map(|(i, &opt_def_id)| {
1539             if let Some(def_id) = opt_def_id {
1540                 if def_id.is_local() {
1541                     return Some((def_id.index, i));
1542                 }
1543             }
1544             None
1545         }))
1546     }
1547
1548     fn encode_lang_items_missing(&mut self) -> LazySeq<lang_items::LangItem> {
1549         let tcx = self.tcx;
1550         self.lazy_seq_ref(&tcx.lang_items().missing)
1551     }
1552
1553     /// Encodes an index, mapping each trait to its (local) implementations.
1554     fn encode_impls(&mut self) -> LazySeq<TraitImpls> {
1555         debug!("EncodeContext::encode_impls()");
1556         let tcx = self.tcx;
1557         let mut visitor = ImplVisitor {
1558             tcx,
1559             impls: FxHashMap::default(),
1560         };
1561         tcx.hir().krate().visit_all_item_likes(&mut visitor);
1562
1563         let mut all_impls: Vec<_> = visitor.impls.into_iter().collect();
1564
1565         // Bring everything into deterministic order for hashing
1566         all_impls.sort_by_cached_key(|&(trait_def_id, _)| {
1567             tcx.def_path_hash(trait_def_id)
1568         });
1569
1570         let all_impls: Vec<_> = all_impls
1571             .into_iter()
1572             .map(|(trait_def_id, mut impls)| {
1573                 // Bring everything into deterministic order for hashing
1574                 impls.sort_by_cached_key(|&def_index| {
1575                     tcx.hir().definitions().def_path_hash(def_index)
1576                 });
1577
1578                 TraitImpls {
1579                     trait_id: (trait_def_id.krate.as_u32(), trait_def_id.index),
1580                     impls: self.lazy_seq_ref(&impls),
1581                 }
1582             })
1583             .collect();
1584
1585         self.lazy_seq_ref(&all_impls)
1586     }
1587
1588     // Encodes all symbols exported from this crate into the metadata.
1589     //
1590     // This pass is seeded off the reachability list calculated in the
1591     // middle::reachable module but filters out items that either don't have a
1592     // symbol associated with them (they weren't translated) or if they're an FFI
1593     // definition (as that's not defined in this crate).
1594     fn encode_exported_symbols(&mut self,
1595                                exported_symbols: &[(ExportedSymbol<'tcx>, SymbolExportLevel)])
1596                                -> LazySeq<(ExportedSymbol<'tcx>, SymbolExportLevel)> {
1597         // The metadata symbol name is special. It should not show up in
1598         // downstream crates.
1599         let metadata_symbol_name = SymbolName::new(&metadata_symbol_name(self.tcx));
1600
1601         self.lazy_seq(exported_symbols
1602             .iter()
1603             .filter(|&&(ref exported_symbol, _)| {
1604                 match *exported_symbol {
1605                     ExportedSymbol::NoDefId(symbol_name) => {
1606                         symbol_name != metadata_symbol_name
1607                     },
1608                     _ => true,
1609                 }
1610             })
1611             .cloned())
1612     }
1613
1614     fn encode_dylib_dependency_formats(&mut self) -> LazySeq<Option<LinkagePreference>> {
1615         match self.tcx.sess.dependency_formats.borrow().get(&config::CrateType::Dylib) {
1616             Some(arr) => {
1617                 self.lazy_seq(arr.iter().map(|slot| {
1618                     match *slot {
1619                         Linkage::NotLinked |
1620                         Linkage::IncludedFromDylib => None,
1621
1622                         Linkage::Dynamic => Some(LinkagePreference::RequireDynamic),
1623                         Linkage::Static => Some(LinkagePreference::RequireStatic),
1624                     }
1625                 }))
1626             }
1627             None => LazySeq::empty(),
1628         }
1629     }
1630
1631     fn encode_info_for_foreign_item(&mut self,
1632                                     (def_id, nitem): (DefId, &hir::ForeignItem))
1633                                     -> Entry<'tcx> {
1634         let tcx = self.tcx;
1635
1636         debug!("EncodeContext::encode_info_for_foreign_item({:?})", def_id);
1637
1638         let kind = match nitem.node {
1639             hir::ForeignItemKind::Fn(_, ref names, _) => {
1640                 let data = FnData {
1641                     constness: hir::Constness::NotConst,
1642                     arg_names: self.encode_fn_arg_names(names),
1643                     sig: self.lazy(&tcx.fn_sig(def_id)),
1644                 };
1645                 EntryKind::ForeignFn(self.lazy(&data))
1646             }
1647             hir::ForeignItemKind::Static(_, hir::MutMutable) => EntryKind::ForeignMutStatic,
1648             hir::ForeignItemKind::Static(_, hir::MutImmutable) => EntryKind::ForeignImmStatic,
1649             hir::ForeignItemKind::Type => EntryKind::ForeignType,
1650         };
1651
1652         Entry {
1653             kind,
1654             visibility: self.lazy(&ty::Visibility::from_hir(&nitem.vis, nitem.hir_id, tcx)),
1655             span: self.lazy(&nitem.span),
1656             attributes: self.encode_attributes(&nitem.attrs),
1657             children: LazySeq::empty(),
1658             stability: self.encode_stability(def_id),
1659             deprecation: self.encode_deprecation(def_id),
1660
1661             ty: Some(self.encode_item_type(def_id)),
1662             inherent_impls: LazySeq::empty(),
1663             variances: match nitem.node {
1664                 hir::ForeignItemKind::Fn(..) => self.encode_variances_of(def_id),
1665                 _ => LazySeq::empty(),
1666             },
1667             generics: Some(self.encode_generics(def_id)),
1668             predicates: Some(self.encode_predicates(def_id)),
1669             predicates_defined_on: None,
1670
1671             mir: None,
1672         }
1673     }
1674 }
1675
1676 impl Visitor<'tcx> for EncodeContext<'tcx> {
1677     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
1678         NestedVisitorMap::OnlyBodies(&self.tcx.hir())
1679     }
1680     fn visit_expr(&mut self, ex: &'tcx hir::Expr) {
1681         intravisit::walk_expr(self, ex);
1682         self.encode_info_for_expr(ex);
1683     }
1684     fn visit_item(&mut self, item: &'tcx hir::Item) {
1685         intravisit::walk_item(self, item);
1686         let def_id = self.tcx.hir().local_def_id(item.hir_id);
1687         match item.node {
1688             hir::ItemKind::ExternCrate(_) |
1689             hir::ItemKind::Use(..) => {} // ignore these
1690             _ => self.record(def_id, EncodeContext::encode_info_for_item, (def_id, item)),
1691         }
1692         self.encode_addl_info_for_item(item);
1693     }
1694     fn visit_foreign_item(&mut self, ni: &'tcx hir::ForeignItem) {
1695         intravisit::walk_foreign_item(self, ni);
1696         let def_id = self.tcx.hir().local_def_id(ni.hir_id);
1697         self.record(def_id,
1698                           EncodeContext::encode_info_for_foreign_item,
1699                           (def_id, ni));
1700     }
1701     fn visit_variant(&mut self,
1702                      v: &'tcx hir::Variant,
1703                      g: &'tcx hir::Generics,
1704                      id: hir::HirId) {
1705         intravisit::walk_variant(self, v, g, id);
1706
1707         if let Some(ref discr) = v.disr_expr {
1708             let def_id = self.tcx.hir().local_def_id(discr.hir_id);
1709             self.record(def_id, EncodeContext::encode_info_for_anon_const, def_id);
1710         }
1711     }
1712     fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
1713         intravisit::walk_generics(self, generics);
1714         self.encode_info_for_generics(generics);
1715     }
1716     fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
1717         intravisit::walk_ty(self, ty);
1718         self.encode_info_for_ty(ty);
1719     }
1720     fn visit_macro_def(&mut self, macro_def: &'tcx hir::MacroDef) {
1721         let def_id = self.tcx.hir().local_def_id(macro_def.hir_id);
1722         self.record(def_id, EncodeContext::encode_info_for_macro_def, macro_def);
1723     }
1724 }
1725
1726 impl EncodeContext<'tcx> {
1727     fn encode_fields(&mut self, adt_def_id: DefId) {
1728         let def = self.tcx.adt_def(adt_def_id);
1729         for (variant_index, variant) in def.variants.iter_enumerated() {
1730             for (field_index, field) in variant.fields.iter().enumerate() {
1731                 self.record(field.did,
1732                             EncodeContext::encode_field,
1733                             (adt_def_id, variant_index, field_index));
1734             }
1735         }
1736     }
1737
1738     fn encode_info_for_generics(&mut self, generics: &hir::Generics) {
1739         for param in &generics.params {
1740             let def_id = self.tcx.hir().local_def_id(param.hir_id);
1741             match param.kind {
1742                 GenericParamKind::Lifetime { .. } => continue,
1743                 GenericParamKind::Type { ref default, .. } => {
1744                     self.record(
1745                         def_id,
1746                         EncodeContext::encode_info_for_ty_param,
1747                         (def_id, default.is_some()),
1748                     );
1749                 }
1750                 GenericParamKind::Const { .. } => {
1751                     self.record(def_id, EncodeContext::encode_info_for_const_param, def_id);
1752                 }
1753             }
1754         }
1755     }
1756
1757     fn encode_info_for_ty(&mut self, ty: &hir::Ty) {
1758         match ty.node {
1759             hir::TyKind::Array(_, ref length) => {
1760                 let def_id = self.tcx.hir().local_def_id(length.hir_id);
1761                 self.record(def_id, EncodeContext::encode_info_for_anon_const, def_id);
1762             }
1763             _ => {}
1764         }
1765     }
1766
1767     fn encode_info_for_expr(&mut self, expr: &hir::Expr) {
1768         match expr.node {
1769             hir::ExprKind::Closure(..) => {
1770                 let def_id = self.tcx.hir().local_def_id(expr.hir_id);
1771                 self.record(def_id, EncodeContext::encode_info_for_closure, def_id);
1772             }
1773             _ => {}
1774         }
1775     }
1776
1777     /// In some cases, along with the item itself, we also
1778     /// encode some sub-items. Usually we want some info from the item
1779     /// so it's easier to do that here then to wait until we would encounter
1780     /// normally in the visitor walk.
1781     fn encode_addl_info_for_item(&mut self, item: &hir::Item) {
1782         let def_id = self.tcx.hir().local_def_id(item.hir_id);
1783         match item.node {
1784             hir::ItemKind::Static(..) |
1785             hir::ItemKind::Const(..) |
1786             hir::ItemKind::Fn(..) |
1787             hir::ItemKind::Mod(..) |
1788             hir::ItemKind::ForeignMod(..) |
1789             hir::ItemKind::GlobalAsm(..) |
1790             hir::ItemKind::ExternCrate(..) |
1791             hir::ItemKind::Use(..) |
1792             hir::ItemKind::TyAlias(..) |
1793             hir::ItemKind::OpaqueTy(..) |
1794             hir::ItemKind::TraitAlias(..) => {
1795                 // no sub-item recording needed in these cases
1796             }
1797             hir::ItemKind::Enum(..) => {
1798                 self.encode_fields(def_id);
1799
1800                 let def = self.tcx.adt_def(def_id);
1801                 for (i, variant) in def.variants.iter_enumerated() {
1802                     self.record(variant.def_id,
1803                                 EncodeContext::encode_enum_variant_info,
1804                                 (def_id, i));
1805
1806                     if let Some(ctor_def_id) = variant.ctor_def_id {
1807                         self.record(ctor_def_id,
1808                                     EncodeContext::encode_enum_variant_ctor,
1809                                     (def_id, i));
1810                     }
1811                 }
1812             }
1813             hir::ItemKind::Struct(ref struct_def, _) => {
1814                 self.encode_fields(def_id);
1815
1816                 // If the struct has a constructor, encode it.
1817                 if let Some(ctor_hir_id) = struct_def.ctor_hir_id() {
1818                     let ctor_def_id = self.tcx.hir().local_def_id(ctor_hir_id);
1819                     self.record(ctor_def_id,
1820                                 EncodeContext::encode_struct_ctor,
1821                                 (def_id, ctor_def_id));
1822                 }
1823             }
1824             hir::ItemKind::Union(..) => {
1825                 self.encode_fields(def_id);
1826             }
1827             hir::ItemKind::Impl(..) => {
1828                 for &trait_item_def_id in self.tcx.associated_item_def_ids(def_id).iter() {
1829                     self.record(trait_item_def_id,
1830                                 EncodeContext::encode_info_for_impl_item,
1831                                 trait_item_def_id);
1832                 }
1833             }
1834             hir::ItemKind::Trait(..) => {
1835                 for &item_def_id in self.tcx.associated_item_def_ids(def_id).iter() {
1836                     self.record(item_def_id,
1837                                 EncodeContext::encode_info_for_trait_item,
1838                                 item_def_id);
1839                 }
1840             }
1841         }
1842     }
1843 }
1844
1845 struct ImplVisitor<'tcx> {
1846     tcx: TyCtxt<'tcx>,
1847     impls: FxHashMap<DefId, Vec<DefIndex>>,
1848 }
1849
1850 impl<'tcx, 'v> ItemLikeVisitor<'v> for ImplVisitor<'tcx> {
1851     fn visit_item(&mut self, item: &hir::Item) {
1852         if let hir::ItemKind::Impl(..) = item.node {
1853             let impl_id = self.tcx.hir().local_def_id(item.hir_id);
1854             if let Some(trait_ref) = self.tcx.impl_trait_ref(impl_id) {
1855                 self.impls
1856                     .entry(trait_ref.def_id)
1857                     .or_default()
1858                     .push(impl_id.index);
1859             }
1860         }
1861     }
1862
1863     fn visit_trait_item(&mut self, _trait_item: &'v hir::TraitItem) {}
1864
1865     fn visit_impl_item(&mut self, _impl_item: &'v hir::ImplItem) {
1866         // handled in `visit_item` above
1867     }
1868 }
1869
1870 // NOTE(eddyb) The following comment was preserved for posterity, even
1871 // though it's no longer relevant as EBML (which uses nested & tagged
1872 // "documents") was replaced with a scheme that can't go out of bounds.
1873 //
1874 // And here we run into yet another obscure archive bug: in which metadata
1875 // loaded from archives may have trailing garbage bytes. Awhile back one of
1876 // our tests was failing sporadically on the macOS 64-bit builders (both nopt
1877 // and opt) by having ebml generate an out-of-bounds panic when looking at
1878 // metadata.
1879 //
1880 // Upon investigation it turned out that the metadata file inside of an rlib
1881 // (and ar archive) was being corrupted. Some compilations would generate a
1882 // metadata file which would end in a few extra bytes, while other
1883 // compilations would not have these extra bytes appended to the end. These
1884 // extra bytes were interpreted by ebml as an extra tag, so they ended up
1885 // being interpreted causing the out-of-bounds.
1886 //
1887 // The root cause of why these extra bytes were appearing was never
1888 // discovered, and in the meantime the solution we're employing is to insert
1889 // the length of the metadata to the start of the metadata. Later on this
1890 // will allow us to slice the metadata to the precise length that we just
1891 // generated regardless of trailing bytes that end up in it.
1892
1893 pub fn encode_metadata(tcx: TyCtxt<'_>) -> EncodedMetadata {
1894     let mut encoder = opaque::Encoder::new(vec![]);
1895     encoder.emit_raw_bytes(METADATA_HEADER);
1896
1897     // Will be filled with the root position after encoding everything.
1898     encoder.emit_raw_bytes(&[0, 0, 0, 0]);
1899
1900     // Since encoding metadata is not in a query, and nothing is cached,
1901     // there's no need to do dep-graph tracking for any of it.
1902     let (root, mut result) = tcx.dep_graph.with_ignore(move || {
1903         let mut ecx = EncodeContext {
1904             opaque: encoder,
1905             tcx,
1906             entries_index: Index::new(tcx.hir().definitions().def_index_count()),
1907             lazy_state: LazyState::NoNode,
1908             type_shorthands: Default::default(),
1909             predicate_shorthands: Default::default(),
1910             source_file_cache: tcx.sess.source_map().files()[0].clone(),
1911             interpret_allocs: Default::default(),
1912             interpret_allocs_inverse: Default::default(),
1913         };
1914
1915         // Encode the rustc version string in a predictable location.
1916         rustc_version().encode(&mut ecx).unwrap();
1917
1918         // Encode all the entries and extra information in the crate,
1919         // culminating in the `CrateRoot` which points to all of it.
1920         let root = ecx.encode_crate_root();
1921         (root, ecx.opaque.into_inner())
1922     });
1923
1924     // Encode the root position.
1925     let header = METADATA_HEADER.len();
1926     let pos = root.position;
1927     result[header + 0] = (pos >> 24) as u8;
1928     result[header + 1] = (pos >> 16) as u8;
1929     result[header + 2] = (pos >> 8) as u8;
1930     result[header + 3] = (pos >> 0) as u8;
1931
1932     EncodedMetadata { raw_data: result }
1933 }
1934
1935 pub fn get_repr_options(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1936     let ty = tcx.type_of(did);
1937     match ty.sty {
1938         ty::Adt(ref def, _) => return def.repr,
1939         _ => bug!("{} is not an ADT", ty),
1940     }
1941 }