src/librustc_metadata/rmeta/encoder.rs

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