src/librustc_metadata/encoder.rs

   1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use index::Index;
  12 use index_builder::{FromId, IndexBuilder, Untracked};
  13 use isolated_encoder::IsolatedEncoder;
  14 use schema::*;
  15
  16 use rustc::middle::cstore::{LinkMeta, LinkagePreference, NativeLibrary,
  17                             EncodedMetadata, EncodedMetadataHashes,
  18                             EncodedMetadataHash};
  19 use rustc::hir::def::CtorKind;
  20 use rustc::hir::def_id::{CrateNum, CRATE_DEF_INDEX, DefIndex, DefId, LOCAL_CRATE};
  21 use rustc::hir::map::definitions::{DefPathTable, GlobalMetaDataKind};
  22 use rustc::ich::Fingerprint;
  23 use rustc::middle::dependency_format::Linkage;
  24 use rustc::middle::lang_items;
  25 use rustc::mir;
  26 use rustc::traits::specialization_graph;
  27 use rustc::ty::{self, Ty, TyCtxt, ReprOptions};
  28
  29 use rustc::session::config::{self, CrateTypeProcMacro};
  30 use rustc::util::nodemap::{FxHashMap, NodeSet};
  31
  32 use rustc_serialize::{Encodable, Encoder, SpecializedEncoder, opaque};
  33
  34 use std::hash::Hash;
  35 use std::intrinsics;
  36 use std::io::prelude::*;
  37 use std::io::Cursor;
  38 use std::path::Path;
  39 use std::rc::Rc;
  40 use std::u32;
  41 use syntax::ast::{self, CRATE_NODE_ID};
  42 use syntax::codemap::Spanned;
  43 use syntax::attr;
  44 use syntax::symbol::Symbol;
  45 use syntax_pos;
  46
  47 use rustc::hir::{self, PatKind};
  48 use rustc::hir::itemlikevisit::ItemLikeVisitor;
  49 use rustc::hir::intravisit::{Visitor, NestedVisitorMap};
  50 use rustc::hir::intravisit;
  51
  52 pub struct EncodeContext<'a, 'tcx: 'a> {
  53     opaque: opaque::Encoder<'a>,
  54     pub tcx: TyCtxt<'a, 'tcx, 'tcx>,
  55     link_meta: &'a LinkMeta,
  56     exported_symbols: &'a NodeSet,
  57
  58     lazy_state: LazyState,
  59     type_shorthands: FxHashMap<Ty<'tcx>, usize>,
  60     predicate_shorthands: FxHashMap<ty::Predicate<'tcx>, usize>,
  61
  62     pub metadata_hashes: EncodedMetadataHashes,
  63     pub compute_ich: bool,
  64 }
  65
  66 macro_rules! encoder_methods {
  67     ($($name:ident($ty:ty);)*) => {
  68         $(fn $name(&mut self, value: $ty) -> Result<(), Self::Error> {
  69             self.opaque.$name(value)
  70         })*
  71     }
  72 }
  73
  74 impl<'a, 'tcx> Encoder for EncodeContext<'a, 'tcx> {
  75     type Error = <opaque::Encoder<'a> as Encoder>::Error;
  76
  77     fn emit_nil(&mut self) -> Result<(), Self::Error> {
  78         Ok(())
  79     }
  80
  81     encoder_methods! {
  82         emit_usize(usize);
  83         emit_u128(u128);
  84         emit_u64(u64);
  85         emit_u32(u32);
  86         emit_u16(u16);
  87         emit_u8(u8);
  88
  89         emit_isize(isize);
  90         emit_i128(i128);
  91         emit_i64(i64);
  92         emit_i32(i32);
  93         emit_i16(i16);
  94         emit_i8(i8);
  95
  96         emit_bool(bool);
  97         emit_f64(f64);
  98         emit_f32(f32);
  99         emit_char(char);
 100         emit_str(&str);
 101     }
 102 }
 103
 104 impl<'a, 'tcx, T> SpecializedEncoder<Lazy<T>> for EncodeContext<'a, 'tcx> {
 105     fn specialized_encode(&mut self, lazy: &Lazy<T>) -> Result<(), Self::Error> {
 106         self.emit_lazy_distance(lazy.position, Lazy::<T>::min_size())
 107     }
 108 }
 109
 110 impl<'a, 'tcx, T> SpecializedEncoder<LazySeq<T>> for EncodeContext<'a, 'tcx> {
 111     fn specialized_encode(&mut self, seq: &LazySeq<T>) -> Result<(), Self::Error> {
 112         self.emit_usize(seq.len)?;
 113         if seq.len == 0 {
 114             return Ok(());
 115         }
 116         self.emit_lazy_distance(seq.position, LazySeq::<T>::min_size(seq.len))
 117     }
 118 }
 119
 120 impl<'a, 'tcx> SpecializedEncoder<Ty<'tcx>> for EncodeContext<'a, 'tcx> {
 121     fn specialized_encode(&mut self, ty: &Ty<'tcx>) -> Result<(), Self::Error> {
 122         self.encode_with_shorthand(ty, &ty.sty, |ecx| &mut ecx.type_shorthands)
 123     }
 124 }
 125
 126 impl<'a, 'tcx> SpecializedEncoder<ty::GenericPredicates<'tcx>> for EncodeContext<'a, 'tcx> {
 127     fn specialized_encode(&mut self,
 128                           predicates: &ty::GenericPredicates<'tcx>)
 129                           -> Result<(), Self::Error> {
 130         predicates.parent.encode(self)?;
 131         predicates.predicates.len().encode(self)?;
 132         for predicate in &predicates.predicates {
 133             self.encode_with_shorthand(predicate, predicate, |ecx| &mut ecx.predicate_shorthands)?
 134         }
 135         Ok(())
 136     }
 137 }
 138
 139 impl<'a, 'tcx> EncodeContext<'a, 'tcx> {
 140
 141     pub fn position(&self) -> usize {
 142         self.opaque.position()
 143     }
 144
 145     fn emit_node<F: FnOnce(&mut Self, usize) -> R, R>(&mut self, f: F) -> R {
 146         assert_eq!(self.lazy_state, LazyState::NoNode);
 147         let pos = self.position();
 148         self.lazy_state = LazyState::NodeStart(pos);
 149         let r = f(self, pos);
 150         self.lazy_state = LazyState::NoNode;
 151         r
 152     }
 153
 154     fn emit_lazy_distance(&mut self,
 155                           position: usize,
 156                           min_size: usize)
 157                           -> Result<(), <Self as Encoder>::Error> {
 158         let min_end = position + min_size;
 159         let distance = match self.lazy_state {
 160             LazyState::NoNode => bug!("emit_lazy_distance: outside of a metadata node"),
 161             LazyState::NodeStart(start) => {
 162                 assert!(min_end <= start);
 163                 start - min_end
 164             }
 165             LazyState::Previous(last_min_end) => {
 166                 assert!(last_min_end <= position);
 167                 position - last_min_end
 168             }
 169         };
 170         self.lazy_state = LazyState::Previous(min_end);
 171         self.emit_usize(distance)
 172     }
 173
 174     pub fn lazy<T: Encodable>(&mut self, value: &T) -> Lazy<T> {
 175         self.emit_node(|ecx, pos| {
 176             value.encode(ecx).unwrap();
 177
 178             assert!(pos + Lazy::<T>::min_size() <= ecx.position());
 179             Lazy::with_position(pos)
 180         })
 181     }
 182
 183     pub fn lazy_seq<I, T>(&mut self, iter: I) -> LazySeq<T>
 184         where I: IntoIterator<Item = T>,
 185               T: Encodable
 186     {
 187         self.emit_node(|ecx, pos| {
 188             let len = iter.into_iter().map(|value| value.encode(ecx).unwrap()).count();
 189
 190             assert!(pos + LazySeq::<T>::min_size(len) <= ecx.position());
 191             LazySeq::with_position_and_length(pos, len)
 192         })
 193     }
 194
 195     pub fn lazy_seq_ref<'b, I, T>(&mut self, iter: I) -> LazySeq<T>
 196         where I: IntoIterator<Item = &'b T>,
 197               T: 'b + Encodable
 198     {
 199         self.emit_node(|ecx, pos| {
 200             let len = iter.into_iter().map(|value| value.encode(ecx).unwrap()).count();
 201
 202             assert!(pos + LazySeq::<T>::min_size(len) <= ecx.position());
 203             LazySeq::with_position_and_length(pos, len)
 204         })
 205     }
 206
 207     /// Encode the given value or a previously cached shorthand.
 208     fn encode_with_shorthand<T, U, M>(&mut self,
 209                                       value: &T,
 210                                       variant: &U,
 211                                       map: M)
 212                                       -> Result<(), <Self as Encoder>::Error>
 213         where M: for<'b> Fn(&'b mut Self) -> &'b mut FxHashMap<T, usize>,
 214               T: Clone + Eq + Hash,
 215               U: Encodable
 216     {
 217         let existing_shorthand = map(self).get(value).cloned();
 218         if let Some(shorthand) = existing_shorthand {
 219             return self.emit_usize(shorthand);
 220         }
 221
 222         let start = self.position();
 223         variant.encode(self)?;
 224         let len = self.position() - start;
 225
 226         // The shorthand encoding uses the same usize as the
 227         // discriminant, with an offset so they can't conflict.
 228         let discriminant = unsafe { intrinsics::discriminant_value(variant) };
 229         assert!(discriminant < SHORTHAND_OFFSET as u64);
 230         let shorthand = start + SHORTHAND_OFFSET;
 231
 232         // Get the number of bits that leb128 could fit
 233         // in the same space as the fully encoded type.
 234         let leb128_bits = len * 7;
 235
 236         // Check that the shorthand is a not longer than the
 237         // full encoding itself, i.e. it's an obvious win.
 238         if leb128_bits >= 64 || (shorthand as u64) < (1 << leb128_bits) {
 239             map(self).insert(value.clone(), shorthand);
 240         }
 241
 242         Ok(())
 243     }
 244
 245     // Encodes something that corresponds to a single DepNode::GlobalMetaData
 246     // and registers the Fingerprint in the `metadata_hashes` map.
 247     pub fn tracked<'x, DATA, R>(&'x mut self,
 248                                 def_index: DefIndex,
 249                                 op: fn(&mut IsolatedEncoder<'x, 'a, 'tcx>, DATA) -> R,
 250                                 data: DATA)
 251                                 -> Tracked<R> {
 252         let mut entry_builder = IsolatedEncoder::new(self);
 253         let ret = op(&mut entry_builder, data);
 254         let (fingerprint, this) = entry_builder.finish();
 255
 256         if let Some(fingerprint) = fingerprint {
 257             this.metadata_hashes.hashes.push(EncodedMetadataHash {
 258                 def_index,
 259                 hash: fingerprint,
 260             })
 261         }
 262
 263         Tracked::new(ret)
 264     }
 265
 266     fn encode_info_for_items(&mut self) -> Index {
 267         let krate = self.tcx.hir.krate();
 268         let mut index = IndexBuilder::new(self);
 269         index.record(DefId::local(CRATE_DEF_INDEX),
 270                      IsolatedEncoder::encode_info_for_mod,
 271                      FromId(CRATE_NODE_ID, (&krate.module, &krate.attrs, &hir::Public)));
 272         let mut visitor = EncodeVisitor { index: index };
 273         krate.visit_all_item_likes(&mut visitor.as_deep_visitor());
 274         for macro_def in &krate.exported_macros {
 275             visitor.visit_macro_def(macro_def);
 276         }
 277         visitor.index.into_items()
 278     }
 279
 280     fn encode_def_path_table(&mut self) -> Lazy<DefPathTable> {
 281         let definitions = self.tcx.hir.definitions();
 282         self.lazy(definitions.def_path_table())
 283     }
 284
 285     fn encode_codemap(&mut self) -> LazySeq<syntax_pos::FileMap> {
 286         let codemap = self.tcx.sess.codemap();
 287         let all_filemaps = codemap.files();
 288
 289         let (working_dir, working_dir_was_remapped) = self.tcx.sess.working_dir.clone();
 290
 291         let adapted = all_filemaps.iter()
 292             .filter(|filemap| {
 293                 // No need to re-export imported filemaps, as any downstream
 294                 // crate will import them from their original source.
 295                 !filemap.is_imported()
 296             })
 297             .map(|filemap| {
 298                 // When exporting FileMaps, we expand all paths to absolute
 299                 // paths because any relative paths are potentially relative to
 300                 // a wrong directory.
 301                 // However, if a path has been modified via
 302                 // `-Zremap-path-prefix` we assume the user has already set
 303                 // things up the way they want and don't touch the path values
 304                 // anymore.
 305                 let name = Path::new(&filemap.name);
 306                 if filemap.name_was_remapped ||
 307                    (name.is_relative() && working_dir_was_remapped) {
 308                     // This path of this FileMap has been modified by
 309                     // path-remapping, so we use it verbatim (and avoid cloning
 310                     // the whole map in the process).
 311                     filemap.clone()
 312                 } else {
 313                     let mut adapted = (**filemap).clone();
 314                     let abs_path = Path::new(&working_dir).join(name)
 315                                                          .to_string_lossy()
 316                                                          .into_owned();
 317                     adapted.name = abs_path;
 318                     Rc::new(adapted)
 319                 }
 320             })
 321             .collect::<Vec<_>>();
 322
 323         self.lazy_seq_ref(adapted.iter().map(|rc| &**rc))
 324     }
 325
 326     fn encode_crate_root(&mut self) -> Lazy<CrateRoot> {
 327         let mut i = self.position();
 328
 329         let tcx = self.tcx;
 330         let global_metadata_def_index = move |kind: GlobalMetaDataKind| {
 331             kind.def_index(tcx.hir.definitions().def_path_table())
 332         };
 333
 334         let crate_deps = self.tracked(
 335             global_metadata_def_index(GlobalMetaDataKind::CrateDeps),
 336             IsolatedEncoder::encode_crate_deps,
 337             ());
 338         let dylib_dependency_formats = self.tracked(
 339             global_metadata_def_index(GlobalMetaDataKind::DylibDependencyFormats),
 340             IsolatedEncoder::encode_dylib_dependency_formats,
 341             ());
 342         let dep_bytes = self.position() - i;
 343
 344         // Encode the language items.
 345         i = self.position();
 346         let lang_items = self.tracked(
 347             global_metadata_def_index(GlobalMetaDataKind::LangItems),
 348             IsolatedEncoder::encode_lang_items,
 349             ());
 350
 351         let lang_items_missing = self.tracked(
 352             global_metadata_def_index(GlobalMetaDataKind::LangItemsMissing),
 353             IsolatedEncoder::encode_lang_items_missing,
 354             ());
 355         let lang_item_bytes = self.position() - i;
 356
 357         // Encode the native libraries used
 358         i = self.position();
 359         let native_libraries = self.tracked(
 360             global_metadata_def_index(GlobalMetaDataKind::NativeLibraries),
 361             IsolatedEncoder::encode_native_libraries,
 362             ());
 363         let native_lib_bytes = self.position() - i;
 364
 365         // Encode codemap
 366         i = self.position();
 367         let codemap = self.encode_codemap();
 368         let codemap_bytes = self.position() - i;
 369
 370         // Encode DefPathTable
 371         i = self.position();
 372         let def_path_table = self.encode_def_path_table();
 373         let def_path_table_bytes = self.position() - i;
 374
 375         // Encode the def IDs of impls, for coherence checking.
 376         i = self.position();
 377         let impls = self.tracked(
 378             global_metadata_def_index(GlobalMetaDataKind::Impls),
 379             IsolatedEncoder::encode_impls,
 380             ());
 381         let impl_bytes = self.position() - i;
 382
 383         // Encode exported symbols info.
 384         i = self.position();
 385         let exported_symbols = self.tracked(
 386             global_metadata_def_index(GlobalMetaDataKind::ExportedSymbols),
 387             IsolatedEncoder::encode_exported_symbols,
 388             self.exported_symbols);
 389         let exported_symbols_bytes = self.position() - i;
 390
 391         // Encode and index the items.
 392         i = self.position();
 393         let items = self.encode_info_for_items();
 394         let item_bytes = self.position() - i;
 395
 396         i = self.position();
 397         let index = items.write_index(&mut self.opaque.cursor);
 398         let index_bytes = self.position() - i;
 399
 400         let tcx = self.tcx;
 401         let link_meta = self.link_meta;
 402         let is_proc_macro = tcx.sess.crate_types.borrow().contains(&CrateTypeProcMacro);
 403         let has_default_lib_allocator =
 404             attr::contains_name(tcx.hir.krate_attrs(), "default_lib_allocator");
 405         let has_global_allocator = tcx.sess.has_global_allocator.get();
 406         let root = self.lazy(&CrateRoot {
 407             name: tcx.crate_name(LOCAL_CRATE),
 408             triple: tcx.sess.opts.target_triple.clone(),
 409             hash: link_meta.crate_hash,
 410             disambiguator: tcx.sess.local_crate_disambiguator(),
 411             panic_strategy: Tracked::new(tcx.sess.panic_strategy()),
 412             has_global_allocator: Tracked::new(has_global_allocator),
 413             has_default_lib_allocator: Tracked::new(has_default_lib_allocator),
 414             plugin_registrar_fn: tcx.sess
 415                 .plugin_registrar_fn
 416                 .get()
 417                 .map(|id| tcx.hir.local_def_id(id).index),
 418             macro_derive_registrar: if is_proc_macro {
 419                 let id = tcx.sess.derive_registrar_fn.get().unwrap();
 420                 Some(tcx.hir.local_def_id(id).index)
 421             } else {
 422                 None
 423             },
 424
 425             crate_deps,
 426             dylib_dependency_formats,
 427             lang_items,
 428             lang_items_missing,
 429             native_libraries,
 430             codemap,
 431             def_path_table,
 432             impls,
 433             exported_symbols,
 434             index,
 435         });
 436
 437         let total_bytes = self.position();
 438
 439         self.metadata_hashes.hashes.push(EncodedMetadataHash {
 440             def_index: global_metadata_def_index(GlobalMetaDataKind::Krate),
 441             hash: Fingerprint::from_smaller_hash(link_meta.crate_hash.as_u64())
 442         });
 443
 444         if self.tcx.sess.meta_stats() {
 445             let mut zero_bytes = 0;
 446             for e in self.opaque.cursor.get_ref() {
 447                 if *e == 0 {
 448                     zero_bytes += 1;
 449                 }
 450             }
 451
 452             println!("metadata stats:");
 453             println!("             dep bytes: {}", dep_bytes);
 454             println!("       lang item bytes: {}", lang_item_bytes);
 455             println!("          native bytes: {}", native_lib_bytes);
 456             println!("         codemap bytes: {}", codemap_bytes);
 457             println!("            impl bytes: {}", impl_bytes);
 458             println!("    exp. symbols bytes: {}", exported_symbols_bytes);
 459             println!("  def-path table bytes: {}", def_path_table_bytes);
 460             println!("            item bytes: {}", item_bytes);
 461             println!("           index bytes: {}", index_bytes);
 462             println!("            zero bytes: {}", zero_bytes);
 463             println!("           total bytes: {}", total_bytes);
 464         }
 465
 466         root
 467     }
 468 }
 469
 470 // These are methods for encoding various things. They are meant to be used with
 471 // IndexBuilder::record() and EncodeContext::tracked(). They actually
 472 // would not have to be methods of IsolatedEncoder (free standing functions
 473 // taking IsolatedEncoder as first argument would be just fine) but by making
 474 // them methods we don't have to repeat the lengthy `<'a, 'b: 'a, 'tcx: 'b>`
 475 // clause again and again.
 476 impl<'a, 'b: 'a, 'tcx: 'b> IsolatedEncoder<'a, 'b, 'tcx> {
 477     fn encode_variances_of(&mut self, def_id: DefId) -> LazySeq<ty::Variance> {
 478         debug!("IsolatedEncoder::encode_variances_of({:?})", def_id);
 479         let tcx = self.tcx;
 480         self.lazy_seq_from_slice(&tcx.variances_of(def_id))
 481     }
 482
 483     fn encode_item_type(&mut self, def_id: DefId) -> Lazy<Ty<'tcx>> {
 484         let tcx = self.tcx;
 485         let ty = tcx.type_of(def_id);
 486         debug!("IsolatedEncoder::encode_item_type({:?}) => {:?}", def_id, ty);
 487         self.lazy(&ty)
 488     }
 489
 490     /// Encode data for the given variant of the given ADT. The
 491     /// index of the variant is untracked: this is ok because we
 492     /// will have to lookup the adt-def by its id, and that gives us
 493     /// the right to access any information in the adt-def (including,
 494     /// e.g., the length of the various vectors).
 495     fn encode_enum_variant_info(&mut self,
 496                                 (enum_did, Untracked(index)): (DefId, Untracked<usize>))
 497                                 -> Entry<'tcx> {
 498         let tcx = self.tcx;
 499         let def = tcx.adt_def(enum_did);
 500         let variant = &def.variants[index];
 501         let def_id = variant.did;
 502         debug!("IsolatedEncoder::encode_enum_variant_info({:?})", def_id);
 503
 504         let data = VariantData {
 505             ctor_kind: variant.ctor_kind,
 506             discr: variant.discr,
 507             struct_ctor: None,
 508             ctor_sig: if variant.ctor_kind == CtorKind::Fn {
 509                 Some(self.lazy(&tcx.fn_sig(def_id)))
 510             } else {
 511                 None
 512             }
 513         };
 514
 515         let enum_id = tcx.hir.as_local_node_id(enum_did).unwrap();
 516         let enum_vis = &tcx.hir.expect_item(enum_id).vis;
 517
 518         Entry {
 519             kind: EntryKind::Variant(self.lazy(&data)),
 520             visibility: self.lazy(&ty::Visibility::from_hir(enum_vis, enum_id, tcx)),
 521             span: self.lazy(&tcx.def_span(def_id)),
 522             attributes: self.encode_attributes(&tcx.get_attrs(def_id)),
 523             children: self.lazy_seq(variant.fields.iter().map(|f| {
 524                 assert!(f.did.is_local());
 525                 f.did.index
 526             })),
 527             stability: self.encode_stability(def_id),
 528             deprecation: self.encode_deprecation(def_id),
 529
 530             ty: Some(self.encode_item_type(def_id)),
 531             inherent_impls: LazySeq::empty(),
 532             variances: if variant.ctor_kind == CtorKind::Fn {
 533                 self.encode_variances_of(def_id)
 534             } else {
 535                 LazySeq::empty()
 536             },
 537             generics: Some(self.encode_generics(def_id)),
 538             predicates: Some(self.encode_predicates(def_id)),
 539
 540             ast: None,
 541             mir: self.encode_optimized_mir(def_id),
 542         }
 543     }
 544
 545     fn encode_info_for_mod(&mut self,
 546                            FromId(id, (md, attrs, vis)): FromId<(&hir::Mod,
 547                                                                  &[ast::Attribute],
 548                                                                  &hir::Visibility)>)
 549                            -> Entry<'tcx> {
 550         let tcx = self.tcx;
 551         let def_id = tcx.hir.local_def_id(id);
 552         debug!("IsolatedEncoder::encode_info_for_mod({:?})", def_id);
 553
 554         let data = ModData {
 555             reexports: match tcx.export_map.get(&id) {
 556                 Some(exports) if *vis == hir::Public => {
 557                     self.lazy_seq_from_slice(exports.as_slice())
 558                 }
 559                 _ => LazySeq::empty(),
 560             },
 561         };
 562
 563         Entry {
 564             kind: EntryKind::Mod(self.lazy(&data)),
 565             visibility: self.lazy(&ty::Visibility::from_hir(vis, id, tcx)),
 566             span: self.lazy(&tcx.def_span(def_id)),
 567             attributes: self.encode_attributes(attrs),
 568             children: self.lazy_seq(md.item_ids.iter().map(|item_id| {
 569                 tcx.hir.local_def_id(item_id.id).index
 570             })),
 571             stability: self.encode_stability(def_id),
 572             deprecation: self.encode_deprecation(def_id),
 573
 574             ty: None,
 575             inherent_impls: LazySeq::empty(),
 576             variances: LazySeq::empty(),
 577             generics: None,
 578             predicates: None,
 579
 580             ast: None,
 581             mir: None
 582         }
 583     }
 584
 585     /// Encode data for the given field of the given variant of the
 586     /// given ADT. The indices of the variant/field are untracked:
 587     /// this is ok because we will have to lookup the adt-def by its
 588     /// id, and that gives us the right to access any information in
 589     /// the adt-def (including, e.g., the length of the various
 590     /// vectors).
 591     fn encode_field(&mut self,
 592                     (adt_def_id, Untracked((variant_index, field_index))): (DefId,
 593                                                                             Untracked<(usize,
 594                                                                                        usize)>))
 595                     -> Entry<'tcx> {
 596         let tcx = self.tcx;
 597         let variant = &tcx.adt_def(adt_def_id).variants[variant_index];
 598         let field = &variant.fields[field_index];
 599
 600         let def_id = field.did;
 601         debug!("IsolatedEncoder::encode_field({:?})", def_id);
 602
 603         let variant_id = tcx.hir.as_local_node_id(variant.did).unwrap();
 604         let variant_data = tcx.hir.expect_variant_data(variant_id);
 605
 606         Entry {
 607             kind: EntryKind::Field,
 608             visibility: self.lazy(&field.vis),
 609             span: self.lazy(&tcx.def_span(def_id)),
 610             attributes: self.encode_attributes(&variant_data.fields()[field_index].attrs),
 611             children: LazySeq::empty(),
 612             stability: self.encode_stability(def_id),
 613             deprecation: self.encode_deprecation(def_id),
 614
 615             ty: Some(self.encode_item_type(def_id)),
 616             inherent_impls: LazySeq::empty(),
 617             variances: LazySeq::empty(),
 618             generics: Some(self.encode_generics(def_id)),
 619             predicates: Some(self.encode_predicates(def_id)),
 620
 621             ast: None,
 622             mir: None,
 623         }
 624     }
 625
 626     fn encode_struct_ctor(&mut self, (adt_def_id, def_id): (DefId, DefId)) -> Entry<'tcx> {
 627         debug!("IsolatedEncoder::encode_struct_ctor({:?})", def_id);
 628         let tcx = self.tcx;
 629         let variant = tcx.adt_def(adt_def_id).struct_variant();
 630
 631         let data = VariantData {
 632             ctor_kind: variant.ctor_kind,
 633             discr: variant.discr,
 634             struct_ctor: Some(def_id.index),
 635             ctor_sig: if variant.ctor_kind == CtorKind::Fn {
 636                 Some(self.lazy(&tcx.fn_sig(def_id)))
 637             } else {
 638                 None
 639             }
 640         };
 641
 642         let struct_id = tcx.hir.as_local_node_id(adt_def_id).unwrap();
 643         let struct_vis = &tcx.hir.expect_item(struct_id).vis;
 644         let mut ctor_vis = ty::Visibility::from_hir(struct_vis, struct_id, tcx);
 645         for field in &variant.fields {
 646             if ctor_vis.is_at_least(field.vis, tcx) {
 647                 ctor_vis = field.vis;
 648             }
 649         }
 650
 651         let repr_options = get_repr_options(&tcx, adt_def_id);
 652
 653         Entry {
 654             kind: EntryKind::Struct(self.lazy(&data), repr_options),
 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
 672             ast: None,
 673             mir: self.encode_optimized_mir(def_id),
 674         }
 675     }
 676
 677     fn encode_generics(&mut self, def_id: DefId) -> Lazy<ty::Generics> {
 678         debug!("IsolatedEncoder::encode_generics({:?})", def_id);
 679         let tcx = self.tcx;
 680         self.lazy(tcx.generics_of(def_id))
 681     }
 682
 683     fn encode_predicates(&mut self, def_id: DefId) -> Lazy<ty::GenericPredicates<'tcx>> {
 684         debug!("IsolatedEncoder::encode_predicates({:?})", def_id);
 685         let tcx = self.tcx;
 686         self.lazy(&tcx.predicates_of(def_id))
 687     }
 688
 689     fn encode_info_for_trait_item(&mut self, def_id: DefId) -> Entry<'tcx> {
 690         debug!("IsolatedEncoder::encode_info_for_trait_item({:?})", def_id);
 691         let tcx = self.tcx;
 692
 693         let node_id = tcx.hir.as_local_node_id(def_id).unwrap();
 694         let ast_item = tcx.hir.expect_trait_item(node_id);
 695         let trait_item = tcx.associated_item(def_id);
 696
 697         let container = match trait_item.defaultness {
 698             hir::Defaultness::Default { has_value: true } =>
 699                 AssociatedContainer::TraitWithDefault,
 700             hir::Defaultness::Default { has_value: false } =>
 701                 AssociatedContainer::TraitRequired,
 702             hir::Defaultness::Final =>
 703                 span_bug!(ast_item.span, "traits cannot have final items"),
 704         };
 705
 706         let kind = match trait_item.kind {
 707             ty::AssociatedKind::Const => {
 708                 EntryKind::AssociatedConst(container, 0)
 709             }
 710             ty::AssociatedKind::Method => {
 711                 let fn_data = if let hir::TraitItemKind::Method(_, ref m) = ast_item.node {
 712                     let arg_names = match *m {
 713                         hir::TraitMethod::Required(ref names) => {
 714                             self.encode_fn_arg_names(names)
 715                         }
 716                         hir::TraitMethod::Provided(body) => {
 717                             self.encode_fn_arg_names_for_body(body)
 718                         }
 719                     };
 720                     FnData {
 721                         constness: hir::Constness::NotConst,
 722                         arg_names,
 723                         sig: self.lazy(&tcx.fn_sig(def_id)),
 724                     }
 725                 } else {
 726                     bug!()
 727                 };
 728                 EntryKind::Method(self.lazy(&MethodData {
 729                     fn_data,
 730                     container,
 731                     has_self: trait_item.method_has_self_argument,
 732                 }))
 733             }
 734             ty::AssociatedKind::Type => EntryKind::AssociatedType(container),
 735         };
 736
 737         Entry {
 738             kind,
 739             visibility: self.lazy(&trait_item.vis),
 740             span: self.lazy(&ast_item.span),
 741             attributes: self.encode_attributes(&ast_item.attrs),
 742             children: LazySeq::empty(),
 743             stability: self.encode_stability(def_id),
 744             deprecation: self.encode_deprecation(def_id),
 745
 746             ty: match trait_item.kind {
 747                 ty::AssociatedKind::Const |
 748                 ty::AssociatedKind::Method => {
 749                     Some(self.encode_item_type(def_id))
 750                 }
 751                 ty::AssociatedKind::Type => {
 752                     if trait_item.defaultness.has_value() {
 753                         Some(self.encode_item_type(def_id))
 754                     } else {
 755                         None
 756                     }
 757                 }
 758             },
 759             inherent_impls: LazySeq::empty(),
 760             variances: if trait_item.kind == ty::AssociatedKind::Method {
 761                 self.encode_variances_of(def_id)
 762             } else {
 763                 LazySeq::empty()
 764             },
 765             generics: Some(self.encode_generics(def_id)),
 766             predicates: Some(self.encode_predicates(def_id)),
 767
 768             ast: if let hir::TraitItemKind::Const(_, Some(body)) = ast_item.node {
 769                 Some(self.encode_body(body))
 770             } else {
 771                 None
 772             },
 773             mir: self.encode_optimized_mir(def_id),
 774         }
 775     }
 776
 777     fn encode_info_for_impl_item(&mut self, def_id: DefId) -> Entry<'tcx> {
 778         debug!("IsolatedEncoder::encode_info_for_impl_item({:?})", def_id);
 779         let tcx = self.tcx;
 780
 781         let node_id = self.tcx.hir.as_local_node_id(def_id).unwrap();
 782         let ast_item = self.tcx.hir.expect_impl_item(node_id);
 783         let impl_item = self.tcx.associated_item(def_id);
 784
 785         let container = match impl_item.defaultness {
 786             hir::Defaultness::Default { has_value: true } => AssociatedContainer::ImplDefault,
 787             hir::Defaultness::Final => AssociatedContainer::ImplFinal,
 788             hir::Defaultness::Default { has_value: false } =>
 789                 span_bug!(ast_item.span, "impl items always have values (currently)"),
 790         };
 791
 792         let kind = match impl_item.kind {
 793             ty::AssociatedKind::Const => {
 794                 EntryKind::AssociatedConst(container,
 795                     self.tcx.at(ast_item.span).mir_const_qualif(def_id))
 796             }
 797             ty::AssociatedKind::Method => {
 798                 let fn_data = if let hir::ImplItemKind::Method(ref sig, body) = ast_item.node {
 799                     FnData {
 800                         constness: sig.constness,
 801                         arg_names: self.encode_fn_arg_names_for_body(body),
 802                         sig: self.lazy(&tcx.fn_sig(def_id)),
 803                     }
 804                 } else {
 805                     bug!()
 806                 };
 807                 EntryKind::Method(self.lazy(&MethodData {
 808                     fn_data,
 809                     container,
 810                     has_self: impl_item.method_has_self_argument,
 811                 }))
 812             }
 813             ty::AssociatedKind::Type => EntryKind::AssociatedType(container)
 814         };
 815
 816         let (ast, mir) = if let hir::ImplItemKind::Const(_, body) = ast_item.node {
 817             (Some(body), true)
 818         } else if let hir::ImplItemKind::Method(ref sig, body) = ast_item.node {
 819             let generics = self.tcx.generics_of(def_id);
 820             let types = generics.parent_types as usize + generics.types.len();
 821             let needs_inline = types > 0 || attr::requests_inline(&ast_item.attrs);
 822             let is_const_fn = sig.constness == hir::Constness::Const;
 823             let ast = if is_const_fn { Some(body) } else { None };
 824             let always_encode_mir = self.tcx.sess.opts.debugging_opts.always_encode_mir;
 825             (ast, needs_inline || is_const_fn || always_encode_mir)
 826         } else {
 827             (None, false)
 828         };
 829
 830         Entry {
 831             kind,
 832             visibility: self.lazy(&impl_item.vis),
 833             span: self.lazy(&ast_item.span),
 834             attributes: self.encode_attributes(&ast_item.attrs),
 835             children: LazySeq::empty(),
 836             stability: self.encode_stability(def_id),
 837             deprecation: self.encode_deprecation(def_id),
 838
 839             ty: Some(self.encode_item_type(def_id)),
 840             inherent_impls: LazySeq::empty(),
 841             variances: if impl_item.kind == ty::AssociatedKind::Method {
 842                 self.encode_variances_of(def_id)
 843             } else {
 844                 LazySeq::empty()
 845             },
 846             generics: Some(self.encode_generics(def_id)),
 847             predicates: Some(self.encode_predicates(def_id)),
 848
 849             ast: ast.map(|body| self.encode_body(body)),
 850             mir: if mir { self.encode_optimized_mir(def_id) } else { None },
 851         }
 852     }
 853
 854     fn encode_fn_arg_names_for_body(&mut self, body_id: hir::BodyId)
 855                                     -> LazySeq<ast::Name> {
 856         let _ignore = self.tcx.dep_graph.in_ignore();
 857         let body = self.tcx.hir.body(body_id);
 858         self.lazy_seq(body.arguments.iter().map(|arg| {
 859             match arg.pat.node {
 860                 PatKind::Binding(_, _, name, _) => name.node,
 861                 _ => Symbol::intern("")
 862             }
 863         }))
 864     }
 865
 866     fn encode_fn_arg_names(&mut self, names: &[Spanned<ast::Name>])
 867                            -> LazySeq<ast::Name> {
 868         self.lazy_seq(names.iter().map(|name| name.node))
 869     }
 870
 871     fn encode_optimized_mir(&mut self, def_id: DefId) -> Option<Lazy<mir::Mir<'tcx>>> {
 872         debug!("EntryBuilder::encode_mir({:?})", def_id);
 873         if self.tcx.mir_keys(LOCAL_CRATE).contains(&def_id) {
 874             let mir = self.tcx.optimized_mir(def_id);
 875             Some(self.lazy(&mir))
 876         } else {
 877             None
 878         }
 879     }
 880
 881     // Encodes the inherent implementations of a structure, enumeration, or trait.
 882     fn encode_inherent_implementations(&mut self, def_id: DefId) -> LazySeq<DefIndex> {
 883         debug!("IsolatedEncoder::encode_inherent_implementations({:?})", def_id);
 884         let implementations = self.tcx.inherent_impls(def_id);
 885         if implementations.is_empty() {
 886             LazySeq::empty()
 887         } else {
 888             self.lazy_seq(implementations.iter().map(|&def_id| {
 889                 assert!(def_id.is_local());
 890                 def_id.index
 891             }))
 892         }
 893     }
 894
 895     fn encode_stability(&mut self, def_id: DefId) -> Option<Lazy<attr::Stability>> {
 896         debug!("IsolatedEncoder::encode_stability({:?})", def_id);
 897         self.tcx.lookup_stability(def_id).map(|stab| self.lazy(stab))
 898     }
 899
 900     fn encode_deprecation(&mut self, def_id: DefId) -> Option<Lazy<attr::Deprecation>> {
 901         debug!("IsolatedEncoder::encode_deprecation({:?})", def_id);
 902         self.tcx.lookup_deprecation(def_id).map(|depr| self.lazy(&depr))
 903     }
 904
 905     fn encode_info_for_item(&mut self, (def_id, item): (DefId, &'tcx hir::Item)) -> Entry<'tcx> {
 906         let tcx = self.tcx;
 907
 908         debug!("IsolatedEncoder::encode_info_for_item({:?})", def_id);
 909
 910         let kind = match item.node {
 911             hir::ItemStatic(_, hir::MutMutable, _) => EntryKind::MutStatic,
 912             hir::ItemStatic(_, hir::MutImmutable, _) => EntryKind::ImmStatic,
 913             hir::ItemConst(..) => {
 914                 EntryKind::Const(tcx.at(item.span).mir_const_qualif(def_id))
 915             }
 916             hir::ItemFn(_, _, constness, .., body) => {
 917                 let data = FnData {
 918                     constness,
 919                     arg_names: self.encode_fn_arg_names_for_body(body),
 920                     sig: self.lazy(&tcx.fn_sig(def_id)),
 921                 };
 922
 923                 EntryKind::Fn(self.lazy(&data))
 924             }
 925             hir::ItemMod(ref m) => {
 926                 return self.encode_info_for_mod(FromId(item.id, (m, &item.attrs, &item.vis)));
 927             }
 928             hir::ItemForeignMod(_) => EntryKind::ForeignMod,
 929             hir::ItemGlobalAsm(..) => EntryKind::GlobalAsm,
 930             hir::ItemTy(..) => EntryKind::Type,
 931             hir::ItemEnum(..) => EntryKind::Enum(get_repr_options(&tcx, def_id)),
 932             hir::ItemStruct(ref struct_def, _) => {
 933                 let variant = tcx.adt_def(def_id).struct_variant();
 934
 935                 // Encode def_ids for each field and method
 936                 // for methods, write all the stuff get_trait_method
 937                 // needs to know
 938                 let struct_ctor = if !struct_def.is_struct() {
 939                     Some(tcx.hir.local_def_id(struct_def.id()).index)
 940                 } else {
 941                     None
 942                 };
 943
 944                 let repr_options = get_repr_options(&tcx, def_id);
 945
 946                 EntryKind::Struct(self.lazy(&VariantData {
 947                     ctor_kind: variant.ctor_kind,
 948                     discr: variant.discr,
 949                     struct_ctor,
 950                     ctor_sig: None,
 951                 }), repr_options)
 952             }
 953             hir::ItemUnion(..) => {
 954                 let variant = tcx.adt_def(def_id).struct_variant();
 955                 let repr_options = get_repr_options(&tcx, def_id);
 956
 957                 EntryKind::Union(self.lazy(&VariantData {
 958                     ctor_kind: variant.ctor_kind,
 959                     discr: variant.discr,
 960                     struct_ctor: None,
 961                     ctor_sig: None,
 962                 }), repr_options)
 963             }
 964             hir::ItemDefaultImpl(..) => {
 965                 let data = ImplData {
 966                     polarity: hir::ImplPolarity::Positive,
 967                     defaultness: hir::Defaultness::Final,
 968                     parent_impl: None,
 969                     coerce_unsized_info: None,
 970                     trait_ref: tcx.impl_trait_ref(def_id).map(|trait_ref| self.lazy(&trait_ref)),
 971                 };
 972
 973                 EntryKind::DefaultImpl(self.lazy(&data))
 974             }
 975             hir::ItemImpl(_, polarity, defaultness, ..) => {
 976                 let trait_ref = tcx.impl_trait_ref(def_id);
 977                 let parent = if let Some(trait_ref) = trait_ref {
 978                     let trait_def = tcx.trait_def(trait_ref.def_id);
 979                     trait_def.ancestors(tcx, def_id).skip(1).next().and_then(|node| {
 980                         match node {
 981                             specialization_graph::Node::Impl(parent) => Some(parent),
 982                             _ => None,
 983                         }
 984                     })
 985                 } else {
 986                     None
 987                 };
 988
 989                 // if this is an impl of `CoerceUnsized`, create its
 990                 // "unsized info", else just store None
 991                 let coerce_unsized_info =
 992                     trait_ref.and_then(|t| {
 993                         if Some(t.def_id) == tcx.lang_items.coerce_unsized_trait() {
 994                             Some(tcx.at(item.span).coerce_unsized_info(def_id))
 995                         } else {
 996                             None
 997                         }
 998                     });
 999
1000                 let data = ImplData {
1001                     polarity,
1002                     defaultness,
1003                     parent_impl: parent,
1004                     coerce_unsized_info,
1005                     trait_ref: trait_ref.map(|trait_ref| self.lazy(&trait_ref)),
1006                 };
1007
1008                 EntryKind::Impl(self.lazy(&data))
1009             }
1010             hir::ItemTrait(..) => {
1011                 let trait_def = tcx.trait_def(def_id);
1012                 let data = TraitData {
1013                     unsafety: trait_def.unsafety,
1014                     paren_sugar: trait_def.paren_sugar,
1015                     has_default_impl: tcx.trait_has_default_impl(def_id),
1016                     super_predicates: self.lazy(&tcx.super_predicates_of(def_id)),
1017                 };
1018
1019                 EntryKind::Trait(self.lazy(&data))
1020             }
1021             hir::ItemExternCrate(_) |
1022             hir::ItemUse(..) => bug!("cannot encode info for item {:?}", item),
1023         };
1024
1025         Entry {
1026             kind,
1027             visibility: self.lazy(&ty::Visibility::from_hir(&item.vis, item.id, tcx)),
1028             span: self.lazy(&item.span),
1029             attributes: self.encode_attributes(&item.attrs),
1030             children: match item.node {
1031                 hir::ItemForeignMod(ref fm) => {
1032                     self.lazy_seq(fm.items
1033                         .iter()
1034                         .map(|foreign_item| tcx.hir.local_def_id(foreign_item.id).index))
1035                 }
1036                 hir::ItemEnum(..) => {
1037                     let def = self.tcx.adt_def(def_id);
1038                     self.lazy_seq(def.variants.iter().map(|v| {
1039                         assert!(v.did.is_local());
1040                         v.did.index
1041                     }))
1042                 }
1043                 hir::ItemStruct(..) |
1044                 hir::ItemUnion(..) => {
1045                     let def = self.tcx.adt_def(def_id);
1046                     self.lazy_seq(def.struct_variant().fields.iter().map(|f| {
1047                         assert!(f.did.is_local());
1048                         f.did.index
1049                     }))
1050                 }
1051                 hir::ItemImpl(..) |
1052                 hir::ItemTrait(..) => {
1053                     self.lazy_seq(tcx.associated_item_def_ids(def_id).iter().map(|&def_id| {
1054                         assert!(def_id.is_local());
1055                         def_id.index
1056                     }))
1057                 }
1058                 _ => LazySeq::empty(),
1059             },
1060             stability: self.encode_stability(def_id),
1061             deprecation: self.encode_deprecation(def_id),
1062
1063             ty: match item.node {
1064                 hir::ItemStatic(..) |
1065                 hir::ItemConst(..) |
1066                 hir::ItemFn(..) |
1067                 hir::ItemTy(..) |
1068                 hir::ItemEnum(..) |
1069                 hir::ItemStruct(..) |
1070                 hir::ItemUnion(..) |
1071                 hir::ItemImpl(..) => Some(self.encode_item_type(def_id)),
1072                 _ => None,
1073             },
1074             inherent_impls: self.encode_inherent_implementations(def_id),
1075             variances: match item.node {
1076                 hir::ItemEnum(..) |
1077                 hir::ItemStruct(..) |
1078                 hir::ItemUnion(..) |
1079                 hir::ItemFn(..) => self.encode_variances_of(def_id),
1080                 _ => LazySeq::empty(),
1081             },
1082             generics: match item.node {
1083                 hir::ItemStatic(..) |
1084                 hir::ItemConst(..) |
1085                 hir::ItemFn(..) |
1086                 hir::ItemTy(..) |
1087                 hir::ItemEnum(..) |
1088                 hir::ItemStruct(..) |
1089                 hir::ItemUnion(..) |
1090                 hir::ItemImpl(..) |
1091                 hir::ItemTrait(..) => Some(self.encode_generics(def_id)),
1092                 _ => None,
1093             },
1094             predicates: match item.node {
1095                 hir::ItemStatic(..) |
1096                 hir::ItemConst(..) |
1097                 hir::ItemFn(..) |
1098                 hir::ItemTy(..) |
1099                 hir::ItemEnum(..) |
1100                 hir::ItemStruct(..) |
1101                 hir::ItemUnion(..) |
1102                 hir::ItemImpl(..) |
1103                 hir::ItemTrait(..) => Some(self.encode_predicates(def_id)),
1104                 _ => None,
1105             },
1106
1107             ast: match item.node {
1108                 hir::ItemConst(_, body) |
1109                 hir::ItemFn(_, _, hir::Constness::Const, _, _, body) => {
1110                     Some(self.encode_body(body))
1111                 }
1112                 _ => None,
1113             },
1114             mir: match item.node {
1115                 hir::ItemStatic(..) if self.tcx.sess.opts.debugging_opts.always_encode_mir => {
1116                     self.encode_optimized_mir(def_id)
1117                 }
1118                 hir::ItemConst(..) => self.encode_optimized_mir(def_id),
1119                 hir::ItemFn(_, _, constness, _, ref generics, _) => {
1120                     let tps_len = generics.ty_params.len();
1121                     let needs_inline = tps_len > 0 || attr::requests_inline(&item.attrs);
1122                     let always_encode_mir = self.tcx.sess.opts.debugging_opts.always_encode_mir;
1123                     if needs_inline || constness == hir::Constness::Const || always_encode_mir {
1124                         self.encode_optimized_mir(def_id)
1125                     } else {
1126                         None
1127                     }
1128                 }
1129                 _ => None,
1130             },
1131         }
1132     }
1133
1134     /// Serialize the text of exported macros
1135     fn encode_info_for_macro_def(&mut self, macro_def: &hir::MacroDef) -> Entry<'tcx> {
1136         use syntax::print::pprust;
1137         let def_id = self.tcx.hir.local_def_id(macro_def.id);
1138         Entry {
1139             kind: EntryKind::MacroDef(self.lazy(&MacroDef {
1140                 body: pprust::tts_to_string(&macro_def.body.trees().collect::<Vec<_>>()),
1141                 legacy: macro_def.legacy,
1142             })),
1143             visibility: self.lazy(&ty::Visibility::Public),
1144             span: self.lazy(&macro_def.span),
1145             attributes: self.encode_attributes(&macro_def.attrs),
1146             stability: self.encode_stability(def_id),
1147             deprecation: self.encode_deprecation(def_id),
1148
1149             children: LazySeq::empty(),
1150             ty: None,
1151             inherent_impls: LazySeq::empty(),
1152             variances: LazySeq::empty(),
1153             generics: None,
1154             predicates: None,
1155             ast: None,
1156             mir: None,
1157         }
1158     }
1159
1160     fn encode_info_for_ty_param(&mut self,
1161                                 (def_id, Untracked(has_default)): (DefId, Untracked<bool>))
1162                                 -> Entry<'tcx> {
1163         debug!("IsolatedEncoder::encode_info_for_ty_param({:?})", def_id);
1164         let tcx = self.tcx;
1165         Entry {
1166             kind: EntryKind::Type,
1167             visibility: self.lazy(&ty::Visibility::Public),
1168             span: self.lazy(&tcx.def_span(def_id)),
1169             attributes: LazySeq::empty(),
1170             children: LazySeq::empty(),
1171             stability: None,
1172             deprecation: None,
1173
1174             ty: if has_default {
1175                 Some(self.encode_item_type(def_id))
1176             } else {
1177                 None
1178             },
1179             inherent_impls: LazySeq::empty(),
1180             variances: LazySeq::empty(),
1181             generics: None,
1182             predicates: None,
1183
1184             ast: None,
1185             mir: None,
1186         }
1187     }
1188
1189     fn encode_info_for_anon_ty(&mut self, def_id: DefId) -> Entry<'tcx> {
1190         debug!("IsolatedEncoder::encode_info_for_anon_ty({:?})", def_id);
1191         let tcx = self.tcx;
1192         Entry {
1193             kind: EntryKind::Type,
1194             visibility: self.lazy(&ty::Visibility::Public),
1195             span: self.lazy(&tcx.def_span(def_id)),
1196             attributes: LazySeq::empty(),
1197             children: LazySeq::empty(),
1198             stability: None,
1199             deprecation: None,
1200
1201             ty: Some(self.encode_item_type(def_id)),
1202             inherent_impls: LazySeq::empty(),
1203             variances: LazySeq::empty(),
1204             generics: Some(self.encode_generics(def_id)),
1205             predicates: Some(self.encode_predicates(def_id)),
1206
1207             ast: None,
1208             mir: None,
1209         }
1210     }
1211
1212     fn encode_info_for_closure(&mut self, def_id: DefId) -> Entry<'tcx> {
1213         debug!("IsolatedEncoder::encode_info_for_closure({:?})", def_id);
1214         let tcx = self.tcx;
1215
1216         let data = ClosureData {
1217             kind: tcx.closure_kind(def_id),
1218             sig: self.lazy(&tcx.fn_sig(def_id)),
1219         };
1220
1221         Entry {
1222             kind: EntryKind::Closure(self.lazy(&data)),
1223             visibility: self.lazy(&ty::Visibility::Public),
1224             span: self.lazy(&tcx.def_span(def_id)),
1225             attributes: self.encode_attributes(&tcx.get_attrs(def_id)),
1226             children: LazySeq::empty(),
1227             stability: None,
1228             deprecation: None,
1229
1230             ty: Some(self.encode_item_type(def_id)),
1231             inherent_impls: LazySeq::empty(),
1232             variances: LazySeq::empty(),
1233             generics: Some(self.encode_generics(def_id)),
1234             predicates: None,
1235
1236             ast: None,
1237             mir: self.encode_optimized_mir(def_id),
1238         }
1239     }
1240
1241     fn encode_info_for_embedded_const(&mut self, def_id: DefId) -> Entry<'tcx> {
1242         debug!("IsolatedEncoder::encode_info_for_embedded_const({:?})", def_id);
1243         let tcx = self.tcx;
1244         let id = tcx.hir.as_local_node_id(def_id).unwrap();
1245         let body = tcx.hir.body_owned_by(id);
1246
1247         Entry {
1248             kind: EntryKind::Const(tcx.mir_const_qualif(def_id)),
1249             visibility: self.lazy(&ty::Visibility::Public),
1250             span: self.lazy(&tcx.def_span(def_id)),
1251             attributes: LazySeq::empty(),
1252             children: LazySeq::empty(),
1253             stability: None,
1254             deprecation: None,
1255
1256             ty: Some(self.encode_item_type(def_id)),
1257             inherent_impls: LazySeq::empty(),
1258             variances: LazySeq::empty(),
1259             generics: Some(self.encode_generics(def_id)),
1260             predicates: Some(self.encode_predicates(def_id)),
1261
1262             ast: Some(self.encode_body(body)),
1263             mir: self.encode_optimized_mir(def_id),
1264         }
1265     }
1266
1267     fn encode_attributes(&mut self, attrs: &[ast::Attribute]) -> LazySeq<ast::Attribute> {
1268         // NOTE: This must use lazy_seq_from_slice(), not lazy_seq() because
1269         //       we rely on the HashStable specialization for [Attribute]
1270         //       to properly filter things out.
1271         self.lazy_seq_from_slice(attrs)
1272     }
1273
1274     fn encode_native_libraries(&mut self, _: ()) -> LazySeq<NativeLibrary> {
1275         let used_libraries = self.tcx.sess.cstore.used_libraries();
1276         self.lazy_seq(used_libraries)
1277     }
1278
1279     fn encode_crate_deps(&mut self, _: ()) -> LazySeq<CrateDep> {
1280         let cstore = &*self.tcx.sess.cstore;
1281         let crates = cstore.crates();
1282
1283         let mut deps = crates
1284             .iter()
1285             .map(|&cnum| {
1286                 let dep = CrateDep {
1287                     name: cstore.original_crate_name(cnum),
1288                     hash: cstore.crate_hash(cnum),
1289                     kind: cstore.dep_kind(cnum),
1290                 };
1291                 (cnum, dep)
1292             })
1293             .collect::<Vec<_>>();
1294
1295         deps.sort_by_key(|&(cnum, _)| cnum);
1296
1297         {
1298             // Sanity-check the crate numbers
1299             let mut expected_cnum = 1;
1300             for &(n, _) in &deps {
1301                 assert_eq!(n, CrateNum::new(expected_cnum));
1302                 expected_cnum += 1;
1303             }
1304         }
1305
1306         // We're just going to write a list of crate 'name-hash-version's, with
1307         // the assumption that they are numbered 1 to n.
1308         // FIXME (#2166): This is not nearly enough to support correct versioning
1309         // but is enough to get transitive crate dependencies working.
1310         self.lazy_seq_ref(deps.iter().map(|&(_, ref dep)| dep))
1311     }
1312
1313     fn encode_lang_items(&mut self, _: ()) -> LazySeq<(DefIndex, usize)> {
1314         let tcx = self.tcx;
1315         let lang_items = tcx.lang_items.items().iter();
1316         self.lazy_seq(lang_items.enumerate().filter_map(|(i, &opt_def_id)| {
1317             if let Some(def_id) = opt_def_id {
1318                 if def_id.is_local() {
1319                     return Some((def_id.index, i));
1320                 }
1321             }
1322             None
1323         }))
1324     }
1325
1326     fn encode_lang_items_missing(&mut self, _: ()) -> LazySeq<lang_items::LangItem> {
1327         let tcx = self.tcx;
1328         self.lazy_seq_ref(&tcx.lang_items.missing)
1329     }
1330
1331     /// Encodes an index, mapping each trait to its (local) implementations.
1332     fn encode_impls(&mut self, _: ()) -> LazySeq<TraitImpls> {
1333         debug!("IsolatedEncoder::encode_impls()");
1334         let tcx = self.tcx;
1335         let mut visitor = ImplVisitor {
1336             tcx,
1337             impls: FxHashMap(),
1338         };
1339         tcx.hir.krate().visit_all_item_likes(&mut visitor);
1340
1341         let mut all_impls: Vec<_> = visitor.impls.into_iter().collect();
1342
1343         // Bring everything into deterministic order for hashing
1344         all_impls.sort_unstable_by_key(|&(trait_def_id, _)| {
1345             tcx.def_path_hash(trait_def_id)
1346         });
1347
1348         let all_impls: Vec<_> = all_impls
1349             .into_iter()
1350             .map(|(trait_def_id, mut impls)| {
1351                 // Bring everything into deterministic order for hashing
1352                 impls.sort_unstable_by_key(|&def_index| {
1353                     tcx.hir.definitions().def_path_hash(def_index)
1354                 });
1355
1356                 TraitImpls {
1357                     trait_id: (trait_def_id.krate.as_u32(), trait_def_id.index),
1358                     impls: self.lazy_seq_from_slice(&impls[..]),
1359                 }
1360             })
1361             .collect();
1362
1363         self.lazy_seq_from_slice(&all_impls[..])
1364     }
1365
1366     // Encodes all symbols exported from this crate into the metadata.
1367     //
1368     // This pass is seeded off the reachability list calculated in the
1369     // middle::reachable module but filters out items that either don't have a
1370     // symbol associated with them (they weren't translated) or if they're an FFI
1371     // definition (as that's not defined in this crate).
1372     fn encode_exported_symbols(&mut self, exported_symbols: &NodeSet) -> LazySeq<DefIndex> {
1373         let tcx = self.tcx;
1374         self.lazy_seq(exported_symbols.iter().map(|&id| tcx.hir.local_def_id(id).index))
1375     }
1376
1377     fn encode_dylib_dependency_formats(&mut self, _: ()) -> LazySeq<Option<LinkagePreference>> {
1378         match self.tcx.sess.dependency_formats.borrow().get(&config::CrateTypeDylib) {
1379             Some(arr) => {
1380                 self.lazy_seq(arr.iter().map(|slot| {
1381                     match *slot {
1382                         Linkage::NotLinked |
1383                         Linkage::IncludedFromDylib => None,
1384
1385                         Linkage::Dynamic => Some(LinkagePreference::RequireDynamic),
1386                         Linkage::Static => Some(LinkagePreference::RequireStatic),
1387                     }
1388                 }))
1389             }
1390             None => LazySeq::empty(),
1391         }
1392     }
1393
1394     fn encode_info_for_foreign_item(&mut self,
1395                                     (def_id, nitem): (DefId, &hir::ForeignItem))
1396                                     -> Entry<'tcx> {
1397         let tcx = self.tcx;
1398
1399         debug!("IsolatedEncoder::encode_info_for_foreign_item({:?})", def_id);
1400
1401         let kind = match nitem.node {
1402             hir::ForeignItemFn(_, ref names, _) => {
1403                 let data = FnData {
1404                     constness: hir::Constness::NotConst,
1405                     arg_names: self.encode_fn_arg_names(names),
1406                     sig: self.lazy(&tcx.fn_sig(def_id)),
1407                 };
1408                 EntryKind::ForeignFn(self.lazy(&data))
1409             }
1410             hir::ForeignItemStatic(_, true) => EntryKind::ForeignMutStatic,
1411             hir::ForeignItemStatic(_, false) => EntryKind::ForeignImmStatic,
1412         };
1413
1414         Entry {
1415             kind,
1416             visibility: self.lazy(&ty::Visibility::from_hir(&nitem.vis, nitem.id, tcx)),
1417             span: self.lazy(&nitem.span),
1418             attributes: self.encode_attributes(&nitem.attrs),
1419             children: LazySeq::empty(),
1420             stability: self.encode_stability(def_id),
1421             deprecation: self.encode_deprecation(def_id),
1422
1423             ty: Some(self.encode_item_type(def_id)),
1424             inherent_impls: LazySeq::empty(),
1425             variances: match nitem.node {
1426                 hir::ForeignItemFn(..) => self.encode_variances_of(def_id),
1427                 _ => LazySeq::empty(),
1428             },
1429             generics: Some(self.encode_generics(def_id)),
1430             predicates: Some(self.encode_predicates(def_id)),
1431
1432             ast: None,
1433             mir: None,
1434         }
1435     }
1436 }
1437
1438 struct EncodeVisitor<'a, 'b: 'a, 'tcx: 'b> {
1439     index: IndexBuilder<'a, 'b, 'tcx>,
1440 }
1441
1442 impl<'a, 'b, 'tcx> Visitor<'tcx> for EncodeVisitor<'a, 'b, 'tcx> {
1443     fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
1444         NestedVisitorMap::OnlyBodies(&self.index.tcx.hir)
1445     }
1446     fn visit_expr(&mut self, ex: &'tcx hir::Expr) {
1447         intravisit::walk_expr(self, ex);
1448         self.index.encode_info_for_expr(ex);
1449     }
1450     fn visit_item(&mut self, item: &'tcx hir::Item) {
1451         intravisit::walk_item(self, item);
1452         let def_id = self.index.tcx.hir.local_def_id(item.id);
1453         match item.node {
1454             hir::ItemExternCrate(_) |
1455             hir::ItemUse(..) => (), // ignore these
1456             _ => self.index.record(def_id, IsolatedEncoder::encode_info_for_item, (def_id, item)),
1457         }
1458         self.index.encode_addl_info_for_item(item);
1459     }
1460     fn visit_foreign_item(&mut self, ni: &'tcx hir::ForeignItem) {
1461         intravisit::walk_foreign_item(self, ni);
1462         let def_id = self.index.tcx.hir.local_def_id(ni.id);
1463         self.index.record(def_id,
1464                           IsolatedEncoder::encode_info_for_foreign_item,
1465                           (def_id, ni));
1466     }
1467     fn visit_variant(&mut self,
1468                      v: &'tcx hir::Variant,
1469                      g: &'tcx hir::Generics,
1470                      id: ast::NodeId) {
1471         intravisit::walk_variant(self, v, g, id);
1472
1473         if let Some(discr) = v.node.disr_expr {
1474             let def_id = self.index.tcx.hir.body_owner_def_id(discr);
1475             self.index.record(def_id, IsolatedEncoder::encode_info_for_embedded_const, def_id);
1476         }
1477     }
1478     fn visit_generics(&mut self, generics: &'tcx hir::Generics) {
1479         intravisit::walk_generics(self, generics);
1480         self.index.encode_info_for_generics(generics);
1481     }
1482     fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
1483         intravisit::walk_ty(self, ty);
1484         self.index.encode_info_for_ty(ty);
1485     }
1486     fn visit_macro_def(&mut self, macro_def: &'tcx hir::MacroDef) {
1487         let def_id = self.index.tcx.hir.local_def_id(macro_def.id);
1488         self.index.record(def_id, IsolatedEncoder::encode_info_for_macro_def, macro_def);
1489     }
1490 }
1491
1492 impl<'a, 'b, 'tcx> IndexBuilder<'a, 'b, 'tcx> {
1493     fn encode_fields(&mut self, adt_def_id: DefId) {
1494         let def = self.tcx.adt_def(adt_def_id);
1495         for (variant_index, variant) in def.variants.iter().enumerate() {
1496             for (field_index, field) in variant.fields.iter().enumerate() {
1497                 self.record(field.did,
1498                             IsolatedEncoder::encode_field,
1499                             (adt_def_id, Untracked((variant_index, field_index))));
1500             }
1501         }
1502     }
1503
1504     fn encode_info_for_generics(&mut self, generics: &hir::Generics) {
1505         for ty_param in &generics.ty_params {
1506             let def_id = self.tcx.hir.local_def_id(ty_param.id);
1507             let has_default = Untracked(ty_param.default.is_some());
1508             self.record(def_id, IsolatedEncoder::encode_info_for_ty_param, (def_id, has_default));
1509         }
1510     }
1511
1512     fn encode_info_for_ty(&mut self, ty: &hir::Ty) {
1513         if let hir::TyImplTrait(_) = ty.node {
1514             let def_id = self.tcx.hir.local_def_id(ty.id);
1515             self.record(def_id, IsolatedEncoder::encode_info_for_anon_ty, def_id);
1516         }
1517     }
1518
1519     fn encode_info_for_expr(&mut self, expr: &hir::Expr) {
1520         match expr.node {
1521             hir::ExprClosure(..) => {
1522                 let def_id = self.tcx.hir.local_def_id(expr.id);
1523                 self.record(def_id, IsolatedEncoder::encode_info_for_closure, def_id);
1524             }
1525             _ => {}
1526         }
1527     }
1528
1529     /// In some cases, along with the item itself, we also
1530     /// encode some sub-items. Usually we want some info from the item
1531     /// so it's easier to do that here then to wait until we would encounter
1532     /// normally in the visitor walk.
1533     fn encode_addl_info_for_item(&mut self, item: &hir::Item) {
1534         let def_id = self.tcx.hir.local_def_id(item.id);
1535         match item.node {
1536             hir::ItemStatic(..) |
1537             hir::ItemConst(..) |
1538             hir::ItemFn(..) |
1539             hir::ItemMod(..) |
1540             hir::ItemForeignMod(..) |
1541             hir::ItemGlobalAsm(..) |
1542             hir::ItemExternCrate(..) |
1543             hir::ItemUse(..) |
1544             hir::ItemDefaultImpl(..) |
1545             hir::ItemTy(..) => {
1546                 // no sub-item recording needed in these cases
1547             }
1548             hir::ItemEnum(..) => {
1549                 self.encode_fields(def_id);
1550
1551                 let def = self.tcx.adt_def(def_id);
1552                 for (i, variant) in def.variants.iter().enumerate() {
1553                     self.record(variant.did,
1554                                 IsolatedEncoder::encode_enum_variant_info,
1555                                 (def_id, Untracked(i)));
1556                 }
1557             }
1558             hir::ItemStruct(ref struct_def, _) => {
1559                 self.encode_fields(def_id);
1560
1561                 // If the struct has a constructor, encode it.
1562                 if !struct_def.is_struct() {
1563                     let ctor_def_id = self.tcx.hir.local_def_id(struct_def.id());
1564                     self.record(ctor_def_id,
1565                                 IsolatedEncoder::encode_struct_ctor,
1566                                 (def_id, ctor_def_id));
1567                 }
1568             }
1569             hir::ItemUnion(..) => {
1570                 self.encode_fields(def_id);
1571             }
1572             hir::ItemImpl(..) => {
1573                 for &trait_item_def_id in self.tcx.associated_item_def_ids(def_id).iter() {
1574                     self.record(trait_item_def_id,
1575                                 IsolatedEncoder::encode_info_for_impl_item,
1576                                 trait_item_def_id);
1577                 }
1578             }
1579             hir::ItemTrait(..) => {
1580                 for &item_def_id in self.tcx.associated_item_def_ids(def_id).iter() {
1581                     self.record(item_def_id,
1582                                 IsolatedEncoder::encode_info_for_trait_item,
1583                                 item_def_id);
1584                 }
1585             }
1586         }
1587     }
1588 }
1589
1590 struct ImplVisitor<'a, 'tcx: 'a> {
1591     tcx: TyCtxt<'a, 'tcx, 'tcx>,
1592     impls: FxHashMap<DefId, Vec<DefIndex>>,
1593 }
1594
1595 impl<'a, 'tcx, 'v> ItemLikeVisitor<'v> for ImplVisitor<'a, 'tcx> {
1596     fn visit_item(&mut self, item: &hir::Item) {
1597         if let hir::ItemImpl(..) = item.node {
1598             let impl_id = self.tcx.hir.local_def_id(item.id);
1599             if let Some(trait_ref) = self.tcx.impl_trait_ref(impl_id) {
1600                 self.impls
1601                     .entry(trait_ref.def_id)
1602                     .or_insert(vec![])
1603                     .push(impl_id.index);
1604             }
1605         }
1606     }
1607
1608     fn visit_trait_item(&mut self, _trait_item: &'v hir::TraitItem) {}
1609
1610     fn visit_impl_item(&mut self, _impl_item: &'v hir::ImplItem) {
1611         // handled in `visit_item` above
1612     }
1613 }
1614
1615 // NOTE(eddyb) The following comment was preserved for posterity, even
1616 // though it's no longer relevant as EBML (which uses nested & tagged
1617 // "documents") was replaced with a scheme that can't go out of bounds.
1618 //
1619 // And here we run into yet another obscure archive bug: in which metadata
1620 // loaded from archives may have trailing garbage bytes. Awhile back one of
1621 // our tests was failing sporadically on the macOS 64-bit builders (both nopt
1622 // and opt) by having ebml generate an out-of-bounds panic when looking at
1623 // metadata.
1624 //
1625 // Upon investigation it turned out that the metadata file inside of an rlib
1626 // (and ar archive) was being corrupted. Some compilations would generate a
1627 // metadata file which would end in a few extra bytes, while other
1628 // compilations would not have these extra bytes appended to the end. These
1629 // extra bytes were interpreted by ebml as an extra tag, so they ended up
1630 // being interpreted causing the out-of-bounds.
1631 //
1632 // The root cause of why these extra bytes were appearing was never
1633 // discovered, and in the meantime the solution we're employing is to insert
1634 // the length of the metadata to the start of the metadata. Later on this
1635 // will allow us to slice the metadata to the precise length that we just
1636 // generated regardless of trailing bytes that end up in it.
1637
1638 pub fn encode_metadata<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
1639                                  link_meta: &LinkMeta,
1640                                  exported_symbols: &NodeSet)
1641                                  -> (EncodedMetadata, EncodedMetadataHashes)
1642 {
1643     let mut cursor = Cursor::new(vec![]);
1644     cursor.write_all(METADATA_HEADER).unwrap();
1645
1646     // Will be filled with the root position after encoding everything.
1647     cursor.write_all(&[0, 0, 0, 0]).unwrap();
1648
1649      let compute_ich = (tcx.sess.opts.debugging_opts.query_dep_graph ||
1650                         tcx.sess.opts.debugging_opts.incremental_cc) &&
1651                         tcx.sess.opts.build_dep_graph();
1652
1653     let (root, metadata_hashes) = {
1654         let mut ecx = EncodeContext {
1655             opaque: opaque::Encoder::new(&mut cursor),
1656             tcx,
1657             link_meta,
1658             exported_symbols,
1659             lazy_state: LazyState::NoNode,
1660             type_shorthands: Default::default(),
1661             predicate_shorthands: Default::default(),
1662             metadata_hashes: EncodedMetadataHashes::new(),
1663             compute_ich,
1664         };
1665
1666         // Encode the rustc version string in a predictable location.
1667         rustc_version().encode(&mut ecx).unwrap();
1668
1669         // Encode all the entries and extra information in the crate,
1670         // culminating in the `CrateRoot` which points to all of it.
1671         let root = ecx.encode_crate_root();
1672         (root, ecx.metadata_hashes)
1673     };
1674     let mut result = cursor.into_inner();
1675
1676     // Encode the root position.
1677     let header = METADATA_HEADER.len();
1678     let pos = root.position;
1679     result[header + 0] = (pos >> 24) as u8;
1680     result[header + 1] = (pos >> 16) as u8;
1681     result[header + 2] = (pos >> 8) as u8;
1682     result[header + 3] = (pos >> 0) as u8;
1683
1684     (EncodedMetadata { raw_data: result }, metadata_hashes)
1685 }
1686
1687 pub fn get_repr_options<'a, 'tcx, 'gcx>(tcx: &TyCtxt<'a, 'tcx, 'gcx>, did: DefId) -> ReprOptions {
1688     let ty = tcx.type_of(did);
1689     match ty.sty {
1690         ty::TyAdt(ref def, _) => return def.repr,
1691         _ => bug!("{} is not an ADT", ty),
1692     }
1693 }