src/librustc_metadata/schema.rs

   1 // Copyright 2012-2016 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 astencode;
  12 use index;
  13
  14 use rustc::hir;
  15 use rustc::hir::def::{self, CtorKind};
  16 use rustc::hir::def_id::{DefIndex, DefId, CrateNum};
  17 use rustc::ich::StableHashingContext;
  18 use rustc::middle::cstore::{DepKind, LinkagePreference, NativeLibrary};
  19 use rustc::middle::lang_items;
  20 use rustc::mir;
  21 use rustc::ty::{self, Ty, ReprOptions};
  22 use rustc_back::PanicStrategy;
  23
  24 use rustc_serialize as serialize;
  25 use syntax::{ast, attr};
  26 use syntax::symbol::Symbol;
  27 use syntax_pos::{self, Span};
  28
  29 use std::marker::PhantomData;
  30 use std::mem;
  31
  32 use rustc_data_structures::stable_hasher::{StableHasher, HashStable,
  33                                            StableHasherResult};
  34
  35 use rustc::dep_graph::{DepGraph, DepNode};
  36
  37 pub fn rustc_version() -> String {
  38     format!("rustc {}",
  39             option_env!("CFG_VERSION").unwrap_or("unknown version"))
  40 }
  41
  42 /// Metadata encoding version.
  43 /// NB: increment this if you change the format of metadata such that
  44 /// the rustc version can't be found to compare with `rustc_version()`.
  45 pub const METADATA_VERSION: u8 = 4;
  46
  47 /// Metadata header which includes `METADATA_VERSION`.
  48 /// To get older versions of rustc to ignore this metadata,
  49 /// there are 4 zero bytes at the start, which are treated
  50 /// as a length of 0 by old compilers.
  51 ///
  52 /// This header is followed by the position of the `CrateRoot`,
  53 /// which is encoded as a 32-bit big-endian unsigned integer,
  54 /// and further followed by the rustc version string.
  55 pub const METADATA_HEADER: &'static [u8; 12] =
  56     &[0, 0, 0, 0, b'r', b'u', b's', b't', 0, 0, 0, METADATA_VERSION];
  57
  58 /// The shorthand encoding uses an enum's variant index `usize`
  59 /// and is offset by this value so it never matches a real variant.
  60 /// This offset is also chosen so that the first byte is never < 0x80.
  61 pub const SHORTHAND_OFFSET: usize = 0x80;
  62
  63 /// A value of type T referred to by its absolute position
  64 /// in the metadata, and which can be decoded lazily.
  65 ///
  66 /// Metadata is effective a tree, encoded in post-order,
  67 /// and with the root's position written next to the header.
  68 /// That means every single `Lazy` points to some previous
  69 /// location in the metadata and is part of a larger node.
  70 ///
  71 /// The first `Lazy` in a node is encoded as the backwards
  72 /// distance from the position where the containing node
  73 /// starts and where the `Lazy` points to, while the rest
  74 /// use the forward distance from the previous `Lazy`.
  75 /// Distances start at 1, as 0-byte nodes are invalid.
  76 /// Also invalid are nodes being referred in a different
  77 /// order than they were encoded in.
  78 #[must_use]
  79 pub struct Lazy<T> {
  80     pub position: usize,
  81     _marker: PhantomData<T>,
  82 }
  83
  84 impl<T> Lazy<T> {
  85     pub fn with_position(position: usize) -> Lazy<T> {
  86         Lazy {
  87             position: position,
  88             _marker: PhantomData,
  89         }
  90     }
  91
  92     /// Returns the minimum encoded size of a value of type `T`.
  93     // FIXME(eddyb) Give better estimates for certain types.
  94     pub fn min_size() -> usize {
  95         1
  96     }
  97 }
  98
  99 impl<T> Copy for Lazy<T> {}
 100 impl<T> Clone for Lazy<T> {
 101     fn clone(&self) -> Self {
 102         *self
 103     }
 104 }
 105
 106 impl<T> serialize::UseSpecializedEncodable for Lazy<T> {}
 107 impl<T> serialize::UseSpecializedDecodable for Lazy<T> {}
 108
 109 impl<CTX, T> HashStable<CTX> for Lazy<T> {
 110     fn hash_stable<W: StableHasherResult>(&self,
 111                                           _: &mut CTX,
 112                                           _: &mut StableHasher<W>) {
 113         // There's nothing to do. Whatever got encoded within this Lazy<>
 114         // wrapper has already been hashed.
 115     }
 116 }
 117
 118 /// A sequence of type T referred to by its absolute position
 119 /// in the metadata and length, and which can be decoded lazily.
 120 /// The sequence is a single node for the purposes of `Lazy`.
 121 ///
 122 /// Unlike `Lazy<Vec<T>>`, the length is encoded next to the
 123 /// position, not at the position, which means that the length
 124 /// doesn't need to be known before encoding all the elements.
 125 ///
 126 /// If the length is 0, no position is encoded, but otherwise,
 127 /// the encoding is that of `Lazy`, with the distinction that
 128 /// the minimal distance the length of the sequence, i.e.
 129 /// it's assumed there's no 0-byte element in the sequence.
 130 #[must_use]
 131 pub struct LazySeq<T> {
 132     pub len: usize,
 133     pub position: usize,
 134     _marker: PhantomData<T>,
 135 }
 136
 137 impl<T> LazySeq<T> {
 138     pub fn empty() -> LazySeq<T> {
 139         LazySeq::with_position_and_length(0, 0)
 140     }
 141
 142     pub fn with_position_and_length(position: usize, len: usize) -> LazySeq<T> {
 143         LazySeq {
 144             len: len,
 145             position: position,
 146             _marker: PhantomData,
 147         }
 148     }
 149
 150     /// Returns the minimum encoded size of `length` values of type `T`.
 151     pub fn min_size(length: usize) -> usize {
 152         length
 153     }
 154 }
 155
 156 impl<T> Copy for LazySeq<T> {}
 157 impl<T> Clone for LazySeq<T> {
 158     fn clone(&self) -> Self {
 159         *self
 160     }
 161 }
 162
 163 impl<T> serialize::UseSpecializedEncodable for LazySeq<T> {}
 164 impl<T> serialize::UseSpecializedDecodable for LazySeq<T> {}
 165
 166 impl<CTX, T> HashStable<CTX> for LazySeq<T> {
 167     fn hash_stable<W: StableHasherResult>(&self,
 168                                           _: &mut CTX,
 169                                           _: &mut StableHasher<W>) {
 170         // There's nothing to do. Whatever got encoded within this Lazy<>
 171         // wrapper has already been hashed.
 172     }
 173 }
 174
 175 /// Encoding / decoding state for `Lazy` and `LazySeq`.
 176 #[derive(Copy, Clone, PartialEq, Eq, Debug)]
 177 pub enum LazyState {
 178     /// Outside of a metadata node.
 179     NoNode,
 180
 181     /// Inside a metadata node, and before any `Lazy` or `LazySeq`.
 182     /// The position is that of the node itself.
 183     NodeStart(usize),
 184
 185     /// Inside a metadata node, with a previous `Lazy` or `LazySeq`.
 186     /// The position is a conservative estimate of where that
 187     /// previous `Lazy` / `LazySeq` would end (see their comments).
 188     Previous(usize),
 189 }
 190
 191 /// A `Tracked<T>` wraps a value so that one can only access it when specifying
 192 /// the `DepNode` for that value. This makes it harder to forget registering
 193 /// reads.
 194 #[derive(RustcEncodable, RustcDecodable)]
 195 pub struct Tracked<T> {
 196     state: T,
 197 }
 198
 199 impl<T> Tracked<T> {
 200     pub fn new(state: T) -> Tracked<T> {
 201         Tracked {
 202             state: state,
 203         }
 204     }
 205
 206     pub fn get(&self, dep_graph: &DepGraph, dep_node: DepNode) -> &T {
 207         dep_graph.read(dep_node);
 208         &self.state
 209     }
 210
 211     pub fn get_untracked(&self) -> &T {
 212         &self.state
 213     }
 214
 215     pub fn map<F, R>(&self, f: F) -> Tracked<R>
 216         where F: FnOnce(&T) -> R
 217     {
 218         Tracked {
 219             state: f(&self.state),
 220         }
 221     }
 222 }
 223
 224 impl<'a, 'gcx, 'tcx, T> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for Tracked<T>
 225     where T: HashStable<StableHashingContext<'a, 'gcx, 'tcx>>
 226 {
 227     fn hash_stable<W: StableHasherResult>(&self,
 228                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
 229                                           hasher: &mut StableHasher<W>) {
 230         let Tracked {
 231             ref state
 232         } = *self;
 233
 234         state.hash_stable(hcx, hasher);
 235     }
 236 }
 237
 238
 239 #[derive(RustcEncodable, RustcDecodable)]
 240 pub struct CrateRoot {
 241     pub name: Symbol,
 242     pub triple: String,
 243     pub hash: hir::svh::Svh,
 244     pub disambiguator: Symbol,
 245     pub panic_strategy: Tracked<PanicStrategy>,
 246     pub has_global_allocator: Tracked<bool>,
 247     pub has_default_lib_allocator: Tracked<bool>,
 248     pub plugin_registrar_fn: Option<DefIndex>,
 249     pub macro_derive_registrar: Option<DefIndex>,
 250
 251     pub crate_deps: Tracked<LazySeq<CrateDep>>,
 252     pub dylib_dependency_formats: Tracked<LazySeq<Option<LinkagePreference>>>,
 253     pub lang_items: Tracked<LazySeq<(DefIndex, usize)>>,
 254     pub lang_items_missing: Tracked<LazySeq<lang_items::LangItem>>,
 255     pub native_libraries: Tracked<LazySeq<NativeLibrary>>,
 256     pub codemap: LazySeq<syntax_pos::FileMap>,
 257     pub def_path_table: Lazy<hir::map::definitions::DefPathTable>,
 258     pub impls: Tracked<LazySeq<TraitImpls>>,
 259     pub exported_symbols: Tracked<LazySeq<DefIndex>>,
 260     pub index: LazySeq<index::Index>,
 261 }
 262
 263 #[derive(RustcEncodable, RustcDecodable)]
 264 pub struct CrateDep {
 265     pub name: ast::Name,
 266     pub hash: hir::svh::Svh,
 267     pub kind: DepKind,
 268 }
 269
 270 impl_stable_hash_for!(struct CrateDep {
 271     name,
 272     hash,
 273     kind
 274 });
 275
 276 #[derive(RustcEncodable, RustcDecodable)]
 277 pub struct TraitImpls {
 278     pub trait_id: (u32, DefIndex),
 279     pub impls: LazySeq<DefIndex>,
 280 }
 281
 282 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for TraitImpls {
 283     fn hash_stable<W: StableHasherResult>(&self,
 284                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
 285                                           hasher: &mut StableHasher<W>) {
 286         let TraitImpls {
 287             trait_id: (krate, def_index),
 288             ref impls,
 289         } = *self;
 290
 291         DefId {
 292             krate: CrateNum::from_u32(krate),
 293             index: def_index
 294         }.hash_stable(hcx, hasher);
 295         impls.hash_stable(hcx, hasher);
 296     }
 297 }
 298
 299 #[derive(RustcEncodable, RustcDecodable)]
 300 pub struct Entry<'tcx> {
 301     pub kind: EntryKind<'tcx>,
 302     pub visibility: Lazy<ty::Visibility>,
 303     pub span: Lazy<Span>,
 304     pub attributes: LazySeq<ast::Attribute>,
 305     pub children: LazySeq<DefIndex>,
 306     pub stability: Option<Lazy<attr::Stability>>,
 307     pub deprecation: Option<Lazy<attr::Deprecation>>,
 308
 309     pub ty: Option<Lazy<Ty<'tcx>>>,
 310     pub inherent_impls: LazySeq<DefIndex>,
 311     pub variances: LazySeq<ty::Variance>,
 312     pub generics: Option<Lazy<ty::Generics>>,
 313     pub predicates: Option<Lazy<ty::GenericPredicates<'tcx>>>,
 314
 315     pub ast: Option<Lazy<astencode::Ast<'tcx>>>,
 316     pub mir: Option<Lazy<mir::Mir<'tcx>>>,
 317 }
 318
 319 impl_stable_hash_for!(struct Entry<'tcx> {
 320     kind,
 321     visibility,
 322     span,
 323     attributes,
 324     children,
 325     stability,
 326     deprecation,
 327     ty,
 328     inherent_impls,
 329     variances,
 330     generics,
 331     predicates,
 332     ast,
 333     mir
 334 });
 335
 336 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
 337 pub enum EntryKind<'tcx> {
 338     Const(u8),
 339     ImmStatic,
 340     MutStatic,
 341     ForeignImmStatic,
 342     ForeignMutStatic,
 343     ForeignMod,
 344     GlobalAsm,
 345     Type,
 346     Enum(ReprOptions),
 347     Field,
 348     Variant(Lazy<VariantData<'tcx>>),
 349     Struct(Lazy<VariantData<'tcx>>, ReprOptions),
 350     Union(Lazy<VariantData<'tcx>>, ReprOptions),
 351     Fn(Lazy<FnData<'tcx>>),
 352     ForeignFn(Lazy<FnData<'tcx>>),
 353     Mod(Lazy<ModData>),
 354     MacroDef(Lazy<MacroDef>),
 355     Closure(Lazy<ClosureData<'tcx>>),
 356     Trait(Lazy<TraitData<'tcx>>),
 357     Impl(Lazy<ImplData<'tcx>>),
 358     DefaultImpl(Lazy<ImplData<'tcx>>),
 359     Method(Lazy<MethodData<'tcx>>),
 360     AssociatedType(AssociatedContainer),
 361     AssociatedConst(AssociatedContainer, u8),
 362 }
 363
 364 impl<'a, 'gcx, 'tcx> HashStable<StableHashingContext<'a, 'gcx, 'tcx>> for EntryKind<'tcx> {
 365     fn hash_stable<W: StableHasherResult>(&self,
 366                                           hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>,
 367                                           hasher: &mut StableHasher<W>) {
 368         mem::discriminant(self).hash_stable(hcx, hasher);
 369         match *self {
 370             EntryKind::ImmStatic        |
 371             EntryKind::MutStatic        |
 372             EntryKind::ForeignImmStatic |
 373             EntryKind::ForeignMutStatic |
 374             EntryKind::ForeignMod       |
 375             EntryKind::GlobalAsm        |
 376             EntryKind::Field |
 377             EntryKind::Type => {
 378                 // Nothing else to hash here.
 379             }
 380             EntryKind::Const(qualif) => {
 381                 qualif.hash_stable(hcx, hasher);
 382             }
 383             EntryKind::Enum(ref repr_options) => {
 384                 repr_options.hash_stable(hcx, hasher);
 385             }
 386             EntryKind::Variant(ref variant_data) => {
 387                 variant_data.hash_stable(hcx, hasher);
 388             }
 389             EntryKind::Struct(ref variant_data, ref repr_options) |
 390             EntryKind::Union(ref variant_data, ref repr_options)  => {
 391                 variant_data.hash_stable(hcx, hasher);
 392                 repr_options.hash_stable(hcx, hasher);
 393             }
 394             EntryKind::Fn(ref fn_data) |
 395             EntryKind::ForeignFn(ref fn_data) => {
 396                 fn_data.hash_stable(hcx, hasher);
 397             }
 398             EntryKind::Mod(ref mod_data) => {
 399                 mod_data.hash_stable(hcx, hasher);
 400             }
 401             EntryKind::MacroDef(ref macro_def) => {
 402                 macro_def.hash_stable(hcx, hasher);
 403             }
 404             EntryKind::Closure(closure_data) => {
 405                 closure_data.hash_stable(hcx, hasher);
 406             }
 407             EntryKind::Trait(ref trait_data) => {
 408                 trait_data.hash_stable(hcx, hasher);
 409             }
 410             EntryKind::DefaultImpl(ref impl_data) |
 411             EntryKind::Impl(ref impl_data) => {
 412                 impl_data.hash_stable(hcx, hasher);
 413             }
 414             EntryKind::Method(ref method_data) => {
 415                 method_data.hash_stable(hcx, hasher);
 416             }
 417             EntryKind::AssociatedType(associated_container) => {
 418                 associated_container.hash_stable(hcx, hasher);
 419             }
 420             EntryKind::AssociatedConst(associated_container, qualif) => {
 421                 associated_container.hash_stable(hcx, hasher);
 422                 qualif.hash_stable(hcx, hasher);
 423             }
 424         }
 425     }
 426 }
 427
 428 #[derive(RustcEncodable, RustcDecodable)]
 429 pub struct ModData {
 430     pub reexports: LazySeq<def::Export>,
 431 }
 432
 433 impl_stable_hash_for!(struct ModData { reexports });
 434
 435 #[derive(RustcEncodable, RustcDecodable)]
 436 pub struct MacroDef {
 437     pub body: String,
 438     pub legacy: bool,
 439 }
 440
 441 impl_stable_hash_for!(struct MacroDef { body, legacy });
 442
 443 #[derive(RustcEncodable, RustcDecodable)]
 444 pub struct FnData<'tcx> {
 445     pub constness: hir::Constness,
 446     pub arg_names: LazySeq<ast::Name>,
 447     pub sig: Lazy<ty::PolyFnSig<'tcx>>,
 448 }
 449
 450 impl_stable_hash_for!(struct FnData<'tcx> { constness, arg_names, sig });
 451
 452 #[derive(RustcEncodable, RustcDecodable)]
 453 pub struct VariantData<'tcx> {
 454     pub ctor_kind: CtorKind,
 455     pub discr: ty::VariantDiscr,
 456
 457     /// If this is a struct's only variant, this
 458     /// is the index of the "struct ctor" item.
 459     pub struct_ctor: Option<DefIndex>,
 460
 461     /// If this is a tuple struct or variant
 462     /// ctor, this is its "function" signature.
 463     pub ctor_sig: Option<Lazy<ty::PolyFnSig<'tcx>>>,
 464 }
 465
 466 impl_stable_hash_for!(struct VariantData<'tcx> {
 467     ctor_kind,
 468     discr,
 469     struct_ctor,
 470     ctor_sig
 471 });
 472
 473 #[derive(RustcEncodable, RustcDecodable)]
 474 pub struct TraitData<'tcx> {
 475     pub unsafety: hir::Unsafety,
 476     pub paren_sugar: bool,
 477     pub has_default_impl: bool,
 478     pub super_predicates: Lazy<ty::GenericPredicates<'tcx>>,
 479 }
 480
 481 impl_stable_hash_for!(struct TraitData<'tcx> {
 482     unsafety,
 483     paren_sugar,
 484     has_default_impl,
 485     super_predicates
 486 });
 487
 488 #[derive(RustcEncodable, RustcDecodable)]
 489 pub struct ImplData<'tcx> {
 490     pub polarity: hir::ImplPolarity,
 491     pub defaultness: hir::Defaultness,
 492     pub parent_impl: Option<DefId>,
 493
 494     /// This is `Some` only for impls of `CoerceUnsized`.
 495     pub coerce_unsized_info: Option<ty::adjustment::CoerceUnsizedInfo>,
 496     pub trait_ref: Option<Lazy<ty::TraitRef<'tcx>>>,
 497 }
 498
 499 impl_stable_hash_for!(struct ImplData<'tcx> {
 500     polarity,
 501     defaultness,
 502     parent_impl,
 503     coerce_unsized_info,
 504     trait_ref
 505 });
 506
 507
 508 /// Describes whether the container of an associated item
 509 /// is a trait or an impl and whether, in a trait, it has
 510 /// a default, or an in impl, whether it's marked "default".
 511 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
 512 pub enum AssociatedContainer {
 513     TraitRequired,
 514     TraitWithDefault,
 515     ImplDefault,
 516     ImplFinal,
 517 }
 518
 519 impl_stable_hash_for!(enum ::schema::AssociatedContainer {
 520     TraitRequired,
 521     TraitWithDefault,
 522     ImplDefault,
 523     ImplFinal
 524 });
 525
 526 impl AssociatedContainer {
 527     pub fn with_def_id(&self, def_id: DefId) -> ty::AssociatedItemContainer {
 528         match *self {
 529             AssociatedContainer::TraitRequired |
 530             AssociatedContainer::TraitWithDefault => ty::TraitContainer(def_id),
 531
 532             AssociatedContainer::ImplDefault |
 533             AssociatedContainer::ImplFinal => ty::ImplContainer(def_id),
 534         }
 535     }
 536
 537     pub fn defaultness(&self) -> hir::Defaultness {
 538         match *self {
 539             AssociatedContainer::TraitRequired => hir::Defaultness::Default {
 540                 has_value: false,
 541             },
 542
 543             AssociatedContainer::TraitWithDefault |
 544             AssociatedContainer::ImplDefault => hir::Defaultness::Default {
 545                 has_value: true,
 546             },
 547
 548             AssociatedContainer::ImplFinal => hir::Defaultness::Final,
 549         }
 550     }
 551 }
 552
 553 #[derive(RustcEncodable, RustcDecodable)]
 554 pub struct MethodData<'tcx> {
 555     pub fn_data: FnData<'tcx>,
 556     pub container: AssociatedContainer,
 557     pub has_self: bool,
 558 }
 559 impl_stable_hash_for!(struct MethodData<'tcx> { fn_data, container, has_self });
 560
 561 #[derive(RustcEncodable, RustcDecodable)]
 562 pub struct ClosureData<'tcx> {
 563     pub kind: ty::ClosureKind,
 564     pub sig: Lazy<ty::PolyFnSig<'tcx>>,
 565 }
 566 impl_stable_hash_for!(struct ClosureData<'tcx> { kind, sig });