1 //! Defines how the compiler represents types internally.
3 //! Two important entities in this module are:
5 //! - [`rustc_middle::ty::Ty`], used to represent the semantics of a type.
6 //! - [`rustc_middle::ty::TyCtxt`], the central data structure in the compiler.
8 //! For more information, see ["The `ty` module: representing types"] in the rustc-dev-guide.
10 //! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html
12 pub use self::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable};
13 pub use self::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
14 pub use self::AssocItemContainer::*;
15 pub use self::BorrowKind::*;
16 pub use self::IntVarValue::*;
17 pub use self::Variance::*;
18 use crate::error::{OpaqueHiddenTypeMismatch, TypeMismatchReason};
19 use crate::metadata::ModChild;
20 use crate::middle::privacy::AccessLevels;
21 use crate::mir::{Body, GeneratorLayout};
22 use crate::traits::{self, Reveal};
24 use crate::ty::fast_reject::SimplifiedType;
25 use crate::ty::util::Discr;
30 use rustc_ast::node_id::NodeMap;
31 use rustc_attr as attr;
32 use rustc_data_structures::fingerprint::Fingerprint;
33 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
34 use rustc_data_structures::intern::{Interned, WithStableHash};
35 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
36 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
38 use rustc_hir::def::{CtorKind, CtorOf, DefKind, LifetimeRes, Res};
39 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap};
41 use rustc_index::vec::IndexVec;
42 use rustc_macros::HashStable;
43 use rustc_query_system::ich::StableHashingContext;
44 use rustc_serialize::{Decodable, Encodable};
45 use rustc_span::hygiene::MacroKind;
46 use rustc_span::symbol::{kw, sym, Ident, Symbol};
47 use rustc_span::{ExpnId, Span};
48 use rustc_target::abi::{Align, VariantIdx};
53 use std::hash::{Hash, Hasher};
54 use std::marker::PhantomData;
56 use std::num::NonZeroUsize;
57 use std::ops::ControlFlow;
60 pub use crate::ty::diagnostics::*;
61 pub use rustc_type_ir::DynKind::*;
62 pub use rustc_type_ir::InferTy::*;
63 pub use rustc_type_ir::RegionKind::*;
64 pub use rustc_type_ir::TyKind::*;
65 pub use rustc_type_ir::*;
67 pub use self::binding::BindingMode;
68 pub use self::binding::BindingMode::*;
69 pub use self::closure::{
70 is_ancestor_or_same_capture, place_to_string_for_capture, BorrowKind, CaptureInfo,
71 CapturedPlace, ClosureKind, MinCaptureInformationMap, MinCaptureList,
72 RootVariableMinCaptureList, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath,
75 pub use self::consts::{
76 Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, UnevaluatedConst, ValTree,
78 pub use self::context::{
79 tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
80 CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorDiagnosticData,
81 GeneratorInteriorTypeCause, GlobalCtxt, Lift, OnDiskCache, TyCtxt, TypeckResults, UserType,
82 UserTypeAnnotationIndex,
84 pub use self::instance::{Instance, InstanceDef};
85 pub use self::list::List;
86 pub use self::parameterized::ParameterizedOverTcx;
87 pub use self::rvalue_scopes::RvalueScopes;
88 pub use self::sty::BoundRegionKind::*;
90 Article, Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar,
91 BoundVariableKind, CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid,
92 EarlyBoundRegion, ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig,
93 FreeRegion, GenSig, GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts,
94 InlineConstSubstsParts, ParamConst, ParamTy, PolyExistentialProjection,
95 PolyExistentialTraitRef, PolyFnSig, PolyGenSig, PolyTraitRef, ProjectionTy, Region, RegionKind,
96 RegionVid, TraitRef, TyKind, TypeAndMut, UpvarSubsts, VarianceDiagInfo,
98 pub use self::trait_def::TraitDef;
101 pub mod abstract_const;
110 pub mod inhabitedness;
112 pub mod normalize_erasing_regions;
136 mod structural_impls;
141 pub type RegisteredTools = FxHashSet<Ident>;
144 pub struct ResolverOutputs {
145 pub visibilities: FxHashMap<LocalDefId, Visibility>,
146 /// This field is used to decide whether we should make `PRIVATE_IN_PUBLIC` a hard error.
147 pub has_pub_restricted: bool,
148 /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
149 pub expn_that_defined: FxHashMap<LocalDefId, ExpnId>,
150 /// Reference span for definitions.
151 pub source_span: IndexVec<LocalDefId, Span>,
152 pub access_levels: AccessLevels,
153 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
154 pub maybe_unused_trait_imports: FxIndexSet<LocalDefId>,
155 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
156 pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
157 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
158 /// Extern prelude entries. The value is `true` if the entry was introduced
159 /// via `extern crate` item and not `--extern` option or compiler built-in.
160 pub extern_prelude: FxHashMap<Symbol, bool>,
161 pub main_def: Option<MainDefinition>,
162 pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
163 /// A list of proc macro LocalDefIds, written out in the order in which
164 /// they are declared in the static array generated by proc_macro_harness.
165 pub proc_macros: Vec<LocalDefId>,
166 /// Mapping from ident span to path span for paths that don't exist as written, but that
167 /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
168 pub confused_type_with_std_module: FxHashMap<Span, Span>,
169 pub registered_tools: RegisteredTools,
172 /// Resolutions that should only be used for lowering.
173 /// This struct is meant to be consumed by lowering.
175 pub struct ResolverAstLowering {
176 pub legacy_const_generic_args: FxHashMap<DefId, Option<Vec<usize>>>,
178 /// Resolutions for nodes that have a single resolution.
179 pub partial_res_map: NodeMap<hir::def::PartialRes>,
180 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
181 pub import_res_map: NodeMap<hir::def::PerNS<Option<Res<ast::NodeId>>>>,
182 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
183 pub label_res_map: NodeMap<ast::NodeId>,
184 /// Resolutions for lifetimes.
185 pub lifetimes_res_map: NodeMap<LifetimeRes>,
186 /// Lifetime parameters that lowering will have to introduce.
187 pub extra_lifetime_params_map: NodeMap<Vec<(Ident, ast::NodeId, LifetimeRes)>>,
189 pub next_node_id: ast::NodeId,
191 pub node_id_to_def_id: FxHashMap<ast::NodeId, LocalDefId>,
192 pub def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
194 pub trait_map: NodeMap<Vec<hir::TraitCandidate>>,
195 /// A small map keeping true kinds of built-in macros that appear to be fn-like on
196 /// the surface (`macro` items in libcore), but are actually attributes or derives.
197 pub builtin_macro_kinds: FxHashMap<LocalDefId, MacroKind>,
200 #[derive(Clone, Copy, Debug)]
201 pub struct MainDefinition {
202 pub res: Res<ast::NodeId>,
207 impl MainDefinition {
208 pub fn opt_fn_def_id(self) -> Option<DefId> {
209 if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
213 /// The "header" of an impl is everything outside the body: a Self type, a trait
214 /// ref (in the case of a trait impl), and a set of predicates (from the
215 /// bounds / where-clauses).
216 #[derive(Clone, Debug, TypeFoldable, TypeVisitable)]
217 pub struct ImplHeader<'tcx> {
218 pub impl_def_id: DefId,
219 pub self_ty: Ty<'tcx>,
220 pub trait_ref: Option<TraitRef<'tcx>>,
221 pub predicates: Vec<Predicate<'tcx>>,
224 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
225 pub enum ImplSubject<'tcx> {
226 Trait(TraitRef<'tcx>),
230 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable, Debug)]
231 #[derive(TypeFoldable, TypeVisitable)]
232 pub enum ImplPolarity {
233 /// `impl Trait for Type`
235 /// `impl !Trait for Type`
237 /// `#[rustc_reservation_impl] impl Trait for Type`
239 /// This is a "stability hack", not a real Rust feature.
240 /// See #64631 for details.
245 /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
246 pub fn flip(&self) -> Option<ImplPolarity> {
248 ImplPolarity::Positive => Some(ImplPolarity::Negative),
249 ImplPolarity::Negative => Some(ImplPolarity::Positive),
250 ImplPolarity::Reservation => None,
255 impl fmt::Display for ImplPolarity {
256 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
258 Self::Positive => f.write_str("positive"),
259 Self::Negative => f.write_str("negative"),
260 Self::Reservation => f.write_str("reservation"),
265 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, Encodable, Decodable, HashStable)]
266 pub enum Visibility<Id = LocalDefId> {
267 /// Visible everywhere (including in other crates).
269 /// Visible only in the given crate-local module.
273 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
274 pub enum BoundConstness {
277 /// `T: ~const Trait`
279 /// Requires resolving to const only when we are in a const context.
283 impl BoundConstness {
284 /// Reduce `self` and `constness` to two possible combined states instead of four.
285 pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
286 match (constness, self) {
287 (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
289 *this = BoundConstness::NotConst;
290 hir::Constness::NotConst
296 impl fmt::Display for BoundConstness {
297 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
299 Self::NotConst => f.write_str("normal"),
300 Self::ConstIfConst => f.write_str("`~const`"),
305 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
306 #[derive(TypeFoldable, TypeVisitable)]
307 pub struct ClosureSizeProfileData<'tcx> {
308 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
309 pub before_feature_tys: Ty<'tcx>,
310 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
311 pub after_feature_tys: Ty<'tcx>,
314 pub trait DefIdTree: Copy {
315 fn opt_parent(self, id: DefId) -> Option<DefId>;
319 fn parent(self, id: DefId) -> DefId {
320 match self.opt_parent(id) {
322 // not `unwrap_or_else` to avoid breaking caller tracking
323 None => bug!("{id:?} doesn't have a parent"),
329 fn opt_local_parent(self, id: LocalDefId) -> Option<LocalDefId> {
330 self.opt_parent(id.to_def_id()).map(DefId::expect_local)
335 fn local_parent(self, id: LocalDefId) -> LocalDefId {
336 self.parent(id.to_def_id()).expect_local()
339 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
340 if descendant.krate != ancestor.krate {
344 while descendant != ancestor {
345 match self.opt_parent(descendant) {
346 Some(parent) => descendant = parent,
347 None => return false,
354 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
356 fn opt_parent(self, id: DefId) -> Option<DefId> {
357 self.def_key(id).parent.map(|index| DefId { index, ..id })
361 impl<Id> Visibility<Id> {
362 pub fn is_public(self) -> bool {
363 matches!(self, Visibility::Public)
366 pub fn map_id<OutId>(self, f: impl FnOnce(Id) -> OutId) -> Visibility<OutId> {
368 Visibility::Public => Visibility::Public,
369 Visibility::Restricted(id) => Visibility::Restricted(f(id)),
374 impl<Id: Into<DefId>> Visibility<Id> {
375 pub fn to_def_id(self) -> Visibility<DefId> {
376 self.map_id(Into::into)
379 /// Returns `true` if an item with this visibility is accessible from the given module.
380 pub fn is_accessible_from(self, module: impl Into<DefId>, tree: impl DefIdTree) -> bool {
382 // Public items are visible everywhere.
383 Visibility::Public => true,
384 Visibility::Restricted(id) => tree.is_descendant_of(module.into(), id.into()),
388 /// Returns `true` if this visibility is at least as accessible as the given visibility
389 pub fn is_at_least(self, vis: Visibility<impl Into<DefId>>, tree: impl DefIdTree) -> bool {
391 Visibility::Public => self.is_public(),
392 Visibility::Restricted(id) => self.is_accessible_from(id, tree),
397 impl Visibility<DefId> {
398 pub fn expect_local(self) -> Visibility {
399 self.map_id(|id| id.expect_local())
402 // Returns `true` if this item is visible anywhere in the local crate.
403 pub fn is_visible_locally(self) -> bool {
405 Visibility::Public => true,
406 Visibility::Restricted(def_id) => def_id.is_local(),
411 /// The crate variances map is computed during typeck and contains the
412 /// variance of every item in the local crate. You should not use it
413 /// directly, because to do so will make your pass dependent on the
414 /// HIR of every item in the local crate. Instead, use
415 /// `tcx.variances_of()` to get the variance for a *particular*
417 #[derive(HashStable, Debug)]
418 pub struct CrateVariancesMap<'tcx> {
419 /// For each item with generics, maps to a vector of the variance
420 /// of its generics. If an item has no generics, it will have no
422 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
425 // Contains information needed to resolve types and (in the future) look up
426 // the types of AST nodes.
427 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
428 pub struct CReaderCacheKey {
429 pub cnum: Option<CrateNum>,
433 /// Represents a type.
436 /// - This is a very "dumb" struct (with no derives and no `impls`).
437 /// - Values of this type are always interned and thus unique, and are stored
438 /// as an `Interned<TyS>`.
439 /// - `Ty` (which contains a reference to a `Interned<TyS>`) or `Interned<TyS>`
440 /// should be used everywhere instead of `TyS`. In particular, `Ty` has most
441 /// of the relevant methods.
442 #[derive(PartialEq, Eq, PartialOrd, Ord)]
443 #[allow(rustc::usage_of_ty_tykind)]
444 pub(crate) struct TyS<'tcx> {
445 /// This field shouldn't be used directly and may be removed in the future.
446 /// Use `Ty::kind()` instead.
449 /// This field provides fast access to information that is also contained
452 /// This field shouldn't be used directly and may be removed in the future.
453 /// Use `Ty::flags()` instead.
456 /// This field provides fast access to information that is also contained
459 /// This is a kind of confusing thing: it stores the smallest
462 /// (a) the binder itself captures nothing but
463 /// (b) all the late-bound things within the type are captured
464 /// by some sub-binder.
466 /// So, for a type without any late-bound things, like `u32`, this
467 /// will be *innermost*, because that is the innermost binder that
468 /// captures nothing. But for a type `&'D u32`, where `'D` is a
469 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
470 /// -- the binder itself does not capture `D`, but `D` is captured
471 /// by an inner binder.
473 /// We call this concept an "exclusive" binder `D` because all
474 /// De Bruijn indices within the type are contained within `0..D`
476 outer_exclusive_binder: ty::DebruijnIndex,
479 /// Use this rather than `TyS`, whenever possible.
480 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
481 #[rustc_diagnostic_item = "Ty"]
482 #[rustc_pass_by_value]
483 pub struct Ty<'tcx>(Interned<'tcx, WithStableHash<TyS<'tcx>>>);
485 impl<'tcx> TyCtxt<'tcx> {
486 /// A "bool" type used in rustc_mir_transform unit tests when we
487 /// have not spun up a TyCtxt.
488 pub const BOOL_TY_FOR_UNIT_TESTING: Ty<'tcx> = Ty(Interned::new_unchecked(&WithStableHash {
491 flags: TypeFlags::empty(),
492 outer_exclusive_binder: DebruijnIndex::from_usize(0),
494 stable_hash: Fingerprint::ZERO,
498 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
500 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
504 // The other fields just provide fast access to information that is
505 // also contained in `kind`, so no need to hash them.
508 outer_exclusive_binder: _,
511 kind.hash_stable(hcx, hasher)
515 impl ty::EarlyBoundRegion {
516 /// Does this early bound region have a name? Early bound regions normally
517 /// always have names except when using anonymous lifetimes (`'_`).
518 pub fn has_name(&self) -> bool {
519 self.name != kw::UnderscoreLifetime
523 /// Represents a predicate.
525 /// See comments on `TyS`, which apply here too (albeit for
526 /// `PredicateS`/`Predicate` rather than `TyS`/`Ty`).
528 pub(crate) struct PredicateS<'tcx> {
529 kind: Binder<'tcx, PredicateKind<'tcx>>,
531 /// See the comment for the corresponding field of [TyS].
532 outer_exclusive_binder: ty::DebruijnIndex,
535 /// Use this rather than `PredicateS`, whenever possible.
536 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
537 #[rustc_pass_by_value]
538 pub struct Predicate<'tcx>(Interned<'tcx, PredicateS<'tcx>>);
540 impl<'tcx> Predicate<'tcx> {
541 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
543 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
548 pub fn flags(self) -> TypeFlags {
553 pub fn outer_exclusive_binder(self) -> DebruijnIndex {
554 self.0.outer_exclusive_binder
557 /// Flips the polarity of a Predicate.
559 /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
560 pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
563 .map_bound(|kind| match kind {
564 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
565 Some(PredicateKind::Trait(TraitPredicate {
568 polarity: polarity.flip()?,
576 Some(tcx.mk_predicate(kind))
579 pub fn without_const(mut self, tcx: TyCtxt<'tcx>) -> Self {
580 if let PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) = self.kind().skip_binder()
581 && constness != BoundConstness::NotConst
583 self = tcx.mk_predicate(self.kind().rebind(PredicateKind::Trait(TraitPredicate {
585 constness: BoundConstness::NotConst,
592 /// Whether this projection can be soundly normalized.
594 /// Wf predicates must not be normalized, as normalization
595 /// can remove required bounds which would cause us to
596 /// unsoundly accept some programs. See #91068.
598 pub fn allow_normalization(self) -> bool {
599 match self.kind().skip_binder() {
600 PredicateKind::WellFormed(_) => false,
601 PredicateKind::Trait(_)
602 | PredicateKind::RegionOutlives(_)
603 | PredicateKind::TypeOutlives(_)
604 | PredicateKind::Projection(_)
605 | PredicateKind::ObjectSafe(_)
606 | PredicateKind::ClosureKind(_, _, _)
607 | PredicateKind::Subtype(_)
608 | PredicateKind::Coerce(_)
609 | PredicateKind::ConstEvaluatable(_)
610 | PredicateKind::ConstEquate(_, _)
611 | PredicateKind::TypeWellFormedFromEnv(_) => true,
616 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
617 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
621 // The other fields just provide fast access to information that is
622 // also contained in `kind`, so no need to hash them.
624 outer_exclusive_binder: _,
627 kind.hash_stable(hcx, hasher);
631 impl rustc_errors::IntoDiagnosticArg for Predicate<'_> {
632 fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
633 rustc_errors::DiagnosticArgValue::Str(std::borrow::Cow::Owned(self.to_string()))
637 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
638 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
639 pub enum PredicateKind<'tcx> {
640 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
641 /// the `Self` type of the trait reference and `A`, `B`, and `C`
642 /// would be the type parameters.
643 Trait(TraitPredicate<'tcx>),
646 RegionOutlives(RegionOutlivesPredicate<'tcx>),
649 TypeOutlives(TypeOutlivesPredicate<'tcx>),
651 /// `where <T as TraitRef>::Name == X`, approximately.
652 /// See the `ProjectionPredicate` struct for details.
653 Projection(ProjectionPredicate<'tcx>),
655 /// No syntax: `T` well-formed.
656 WellFormed(GenericArg<'tcx>),
658 /// Trait must be object-safe.
661 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
662 /// for some substitutions `...` and `T` being a closure type.
663 /// Satisfied (or refuted) once we know the closure's kind.
664 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
668 /// This obligation is created most often when we have two
669 /// unresolved type variables and hence don't have enough
670 /// information to process the subtyping obligation yet.
671 Subtype(SubtypePredicate<'tcx>),
673 /// `T1` coerced to `T2`
675 /// Like a subtyping obligation, this is created most often
676 /// when we have two unresolved type variables and hence
677 /// don't have enough information to process the coercion
678 /// obligation yet. At the moment, we actually process coercions
679 /// very much like subtyping and don't handle the full coercion
681 Coerce(CoercePredicate<'tcx>),
683 /// Constant initializer must evaluate successfully.
684 ConstEvaluatable(ty::UnevaluatedConst<'tcx>),
686 /// Constants must be equal. The first component is the const that is expected.
687 ConstEquate(Const<'tcx>, Const<'tcx>),
689 /// Represents a type found in the environment that we can use for implied bounds.
691 /// Only used for Chalk.
692 TypeWellFormedFromEnv(Ty<'tcx>),
695 /// The crate outlives map is computed during typeck and contains the
696 /// outlives of every item in the local crate. You should not use it
697 /// directly, because to do so will make your pass dependent on the
698 /// HIR of every item in the local crate. Instead, use
699 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
701 #[derive(HashStable, Debug)]
702 pub struct CratePredicatesMap<'tcx> {
703 /// For each struct with outlive bounds, maps to a vector of the
704 /// predicate of its outlive bounds. If an item has no outlives
705 /// bounds, it will have no entry.
706 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
709 impl<'tcx> Predicate<'tcx> {
710 /// Performs a substitution suitable for going from a
711 /// poly-trait-ref to supertraits that must hold if that
712 /// poly-trait-ref holds. This is slightly different from a normal
713 /// substitution in terms of what happens with bound regions. See
714 /// lengthy comment below for details.
715 pub fn subst_supertrait(
718 trait_ref: &ty::PolyTraitRef<'tcx>,
719 ) -> Predicate<'tcx> {
720 // The interaction between HRTB and supertraits is not entirely
721 // obvious. Let me walk you (and myself) through an example.
723 // Let's start with an easy case. Consider two traits:
725 // trait Foo<'a>: Bar<'a,'a> { }
726 // trait Bar<'b,'c> { }
728 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
729 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
730 // knew that `Foo<'x>` (for any 'x) then we also know that
731 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
732 // normal substitution.
734 // In terms of why this is sound, the idea is that whenever there
735 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
736 // holds. So if there is an impl of `T:Foo<'a>` that applies to
737 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
740 // Another example to be careful of is this:
742 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
743 // trait Bar1<'b,'c> { }
745 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
746 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
747 // reason is similar to the previous example: any impl of
748 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
749 // basically we would want to collapse the bound lifetimes from
750 // the input (`trait_ref`) and the supertraits.
752 // To achieve this in practice is fairly straightforward. Let's
753 // consider the more complicated scenario:
755 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
756 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
757 // where both `'x` and `'b` would have a DB index of 1.
758 // The substitution from the input trait-ref is therefore going to be
759 // `'a => 'x` (where `'x` has a DB index of 1).
760 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
761 // early-bound parameter and `'b' is a late-bound parameter with a
763 // - If we replace `'a` with `'x` from the input, it too will have
764 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
765 // just as we wanted.
767 // There is only one catch. If we just apply the substitution `'a
768 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
769 // adjust the DB index because we substituting into a binder (it
770 // tries to be so smart...) resulting in `for<'x> for<'b>
771 // Bar1<'x,'b>` (we have no syntax for this, so use your
772 // imagination). Basically the 'x will have DB index of 2 and 'b
773 // will have DB index of 1. Not quite what we want. So we apply
774 // the substitution to the *contents* of the trait reference,
775 // rather than the trait reference itself (put another way, the
776 // substitution code expects equal binding levels in the values
777 // from the substitution and the value being substituted into, and
778 // this trick achieves that).
780 // Working through the second example:
781 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
782 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
783 // We want to end up with:
784 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
786 // 1) We must shift all bound vars in predicate by the length
787 // of trait ref's bound vars. So, we would end up with predicate like
788 // Self: Bar1<'a, '^0.1>
789 // 2) We can then apply the trait substs to this, ending up with
790 // T: Bar1<'^0.0, '^0.1>
791 // 3) Finally, to create the final bound vars, we concatenate the bound
792 // vars of the trait ref with those of the predicate:
794 let bound_pred = self.kind();
795 let pred_bound_vars = bound_pred.bound_vars();
796 let trait_bound_vars = trait_ref.bound_vars();
797 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
799 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
800 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
801 let new = EarlyBinder(shifted_pred).subst(tcx, trait_ref.skip_binder().substs);
802 // 3) ['x] + ['b] -> ['x, 'b]
804 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
805 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
809 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
810 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
811 pub struct TraitPredicate<'tcx> {
812 pub trait_ref: TraitRef<'tcx>,
814 pub constness: BoundConstness,
816 /// If polarity is Positive: we are proving that the trait is implemented.
818 /// If polarity is Negative: we are proving that a negative impl of this trait
819 /// exists. (Note that coherence also checks whether negative impls of supertraits
820 /// exist via a series of predicates.)
822 /// If polarity is Reserved: that's a bug.
823 pub polarity: ImplPolarity,
826 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
828 impl<'tcx> TraitPredicate<'tcx> {
829 pub fn remap_constness(&mut self, param_env: &mut ParamEnv<'tcx>) {
830 *param_env = param_env.with_constness(self.constness.and(param_env.constness()))
833 /// Remap the constness of this predicate before emitting it for diagnostics.
834 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
835 // this is different to `remap_constness` that callees want to print this predicate
836 // in case of selection errors. `T: ~const Drop` bounds cannot end up here when the
837 // param_env is not const because it is always satisfied in non-const contexts.
838 if let hir::Constness::NotConst = param_env.constness() {
839 self.constness = ty::BoundConstness::NotConst;
843 pub fn def_id(self) -> DefId {
844 self.trait_ref.def_id
847 pub fn self_ty(self) -> Ty<'tcx> {
848 self.trait_ref.self_ty()
852 pub fn is_const_if_const(self) -> bool {
853 self.constness == BoundConstness::ConstIfConst
856 pub fn is_constness_satisfied_by(self, constness: hir::Constness) -> bool {
857 match (self.constness, constness) {
858 (BoundConstness::NotConst, _)
859 | (BoundConstness::ConstIfConst, hir::Constness::Const) => true,
860 (BoundConstness::ConstIfConst, hir::Constness::NotConst) => false,
864 pub fn without_const(mut self) -> Self {
865 self.constness = BoundConstness::NotConst;
870 impl<'tcx> PolyTraitPredicate<'tcx> {
871 pub fn def_id(self) -> DefId {
872 // Ok to skip binder since trait `DefId` does not care about regions.
873 self.skip_binder().def_id()
876 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
877 self.map_bound(|trait_ref| trait_ref.self_ty())
880 /// Remap the constness of this predicate before emitting it for diagnostics.
881 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
882 *self = self.map_bound(|mut p| {
883 p.remap_constness_diag(param_env);
889 pub fn is_const_if_const(self) -> bool {
890 self.skip_binder().is_const_if_const()
894 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
895 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
896 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
897 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
898 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
899 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
900 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
902 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
903 /// whether the `a` type is the type that we should label as "expected" when
904 /// presenting user diagnostics.
905 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
906 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
907 pub struct SubtypePredicate<'tcx> {
908 pub a_is_expected: bool,
912 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
914 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
915 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
916 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
917 pub struct CoercePredicate<'tcx> {
921 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
923 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
924 pub struct Term<'tcx> {
926 marker: PhantomData<(Ty<'tcx>, Const<'tcx>)>,
929 impl Debug for Term<'_> {
930 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
931 let data = if let Some(ty) = self.ty() {
932 format!("Term::Ty({:?})", ty)
933 } else if let Some(ct) = self.ct() {
934 format!("Term::Ct({:?})", ct)
942 impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
943 fn from(ty: Ty<'tcx>) -> Self {
944 TermKind::Ty(ty).pack()
948 impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
949 fn from(c: Const<'tcx>) -> Self {
950 TermKind::Const(c).pack()
954 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Term<'tcx> {
955 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
956 self.unpack().hash_stable(hcx, hasher);
960 impl<'tcx> TypeFoldable<'tcx> for Term<'tcx> {
961 fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
962 Ok(self.unpack().try_fold_with(folder)?.pack())
966 impl<'tcx> TypeVisitable<'tcx> for Term<'tcx> {
967 fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
968 self.unpack().visit_with(visitor)
972 impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for Term<'tcx> {
973 fn encode(&self, e: &mut E) {
974 self.unpack().encode(e)
978 impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for Term<'tcx> {
979 fn decode(d: &mut D) -> Self {
980 let res: TermKind<'tcx> = Decodable::decode(d);
985 impl<'tcx> Term<'tcx> {
987 pub fn unpack(self) -> TermKind<'tcx> {
988 let ptr = self.ptr.get();
989 // SAFETY: use of `Interned::new_unchecked` here is ok because these
990 // pointers were originally created from `Interned` types in `pack()`,
991 // and this is just going in the other direction.
993 match ptr & TAG_MASK {
994 TYPE_TAG => TermKind::Ty(Ty(Interned::new_unchecked(
995 &*((ptr & !TAG_MASK) as *const WithStableHash<ty::TyS<'tcx>>),
997 CONST_TAG => TermKind::Const(ty::Const(Interned::new_unchecked(
998 &*((ptr & !TAG_MASK) as *const ty::ConstS<'tcx>),
1000 _ => core::intrinsics::unreachable(),
1005 pub fn ty(&self) -> Option<Ty<'tcx>> {
1006 if let TermKind::Ty(ty) = self.unpack() { Some(ty) } else { None }
1009 pub fn ct(&self) -> Option<Const<'tcx>> {
1010 if let TermKind::Const(c) = self.unpack() { Some(c) } else { None }
1013 pub fn into_arg(self) -> GenericArg<'tcx> {
1014 match self.unpack() {
1015 TermKind::Ty(ty) => ty.into(),
1016 TermKind::Const(c) => c.into(),
1021 const TAG_MASK: usize = 0b11;
1022 const TYPE_TAG: usize = 0b00;
1023 const CONST_TAG: usize = 0b01;
1025 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)]
1026 #[derive(HashStable, TypeFoldable, TypeVisitable)]
1027 pub enum TermKind<'tcx> {
1032 impl<'tcx> TermKind<'tcx> {
1034 fn pack(self) -> Term<'tcx> {
1035 let (tag, ptr) = match self {
1036 TermKind::Ty(ty) => {
1037 // Ensure we can use the tag bits.
1038 assert_eq!(mem::align_of_val(&*ty.0.0) & TAG_MASK, 0);
1039 (TYPE_TAG, ty.0.0 as *const WithStableHash<ty::TyS<'tcx>> as usize)
1041 TermKind::Const(ct) => {
1042 // Ensure we can use the tag bits.
1043 assert_eq!(mem::align_of_val(&*ct.0.0) & TAG_MASK, 0);
1044 (CONST_TAG, ct.0.0 as *const ty::ConstS<'tcx> as usize)
1048 Term { ptr: unsafe { NonZeroUsize::new_unchecked(ptr | tag) }, marker: PhantomData }
1052 /// This kind of predicate has no *direct* correspondent in the
1053 /// syntax, but it roughly corresponds to the syntactic forms:
1055 /// 1. `T: TraitRef<..., Item = Type>`
1056 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1058 /// In particular, form #1 is "desugared" to the combination of a
1059 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1060 /// predicates. Form #2 is a broader form in that it also permits
1061 /// equality between arbitrary types. Processing an instance of
1062 /// Form #2 eventually yields one of these `ProjectionPredicate`
1063 /// instances to normalize the LHS.
1064 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1065 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1066 pub struct ProjectionPredicate<'tcx> {
1067 pub projection_ty: ProjectionTy<'tcx>,
1068 pub term: Term<'tcx>,
1071 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
1073 impl<'tcx> PolyProjectionPredicate<'tcx> {
1074 /// Returns the `DefId` of the trait of the associated item being projected.
1076 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1077 self.skip_binder().projection_ty.trait_def_id(tcx)
1080 /// Get the [PolyTraitRef] required for this projection to be well formed.
1081 /// Note that for generic associated types the predicates of the associated
1082 /// type also need to be checked.
1084 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
1085 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1086 // `self.0.trait_ref` is permitted to have escaping regions.
1087 // This is because here `self` has a `Binder` and so does our
1088 // return value, so we are preserving the number of binding
1090 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1093 pub fn term(&self) -> Binder<'tcx, Term<'tcx>> {
1094 self.map_bound(|predicate| predicate.term)
1097 /// The `DefId` of the `TraitItem` for the associated type.
1099 /// Note that this is not the `DefId` of the `TraitRef` containing this
1100 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1101 pub fn projection_def_id(&self) -> DefId {
1102 // Ok to skip binder since trait `DefId` does not care about regions.
1103 self.skip_binder().projection_ty.item_def_id
1107 pub trait ToPolyTraitRef<'tcx> {
1108 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1111 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1112 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1113 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1117 pub trait ToPredicate<'tcx> {
1118 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
1121 impl<'tcx> ToPredicate<'tcx> for Predicate<'tcx> {
1122 fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1127 impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
1129 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1130 tcx.mk_predicate(self)
1134 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
1135 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1136 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
1140 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1141 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1142 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
1146 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1147 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1148 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
1152 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1153 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1154 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
1158 impl<'tcx> Predicate<'tcx> {
1159 pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
1160 let predicate = self.kind();
1161 match predicate.skip_binder() {
1162 PredicateKind::Trait(t) => Some(predicate.rebind(t)),
1163 PredicateKind::Projection(..)
1164 | PredicateKind::Subtype(..)
1165 | PredicateKind::Coerce(..)
1166 | PredicateKind::RegionOutlives(..)
1167 | PredicateKind::WellFormed(..)
1168 | PredicateKind::ObjectSafe(..)
1169 | PredicateKind::ClosureKind(..)
1170 | PredicateKind::TypeOutlives(..)
1171 | PredicateKind::ConstEvaluatable(..)
1172 | PredicateKind::ConstEquate(..)
1173 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1177 pub fn to_opt_poly_projection_pred(self) -> Option<PolyProjectionPredicate<'tcx>> {
1178 let predicate = self.kind();
1179 match predicate.skip_binder() {
1180 PredicateKind::Projection(t) => Some(predicate.rebind(t)),
1181 PredicateKind::Trait(..)
1182 | PredicateKind::Subtype(..)
1183 | PredicateKind::Coerce(..)
1184 | PredicateKind::RegionOutlives(..)
1185 | PredicateKind::WellFormed(..)
1186 | PredicateKind::ObjectSafe(..)
1187 | PredicateKind::ClosureKind(..)
1188 | PredicateKind::TypeOutlives(..)
1189 | PredicateKind::ConstEvaluatable(..)
1190 | PredicateKind::ConstEquate(..)
1191 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1195 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1196 let predicate = self.kind();
1197 match predicate.skip_binder() {
1198 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
1199 PredicateKind::Trait(..)
1200 | PredicateKind::Projection(..)
1201 | PredicateKind::Subtype(..)
1202 | PredicateKind::Coerce(..)
1203 | PredicateKind::RegionOutlives(..)
1204 | PredicateKind::WellFormed(..)
1205 | PredicateKind::ObjectSafe(..)
1206 | PredicateKind::ClosureKind(..)
1207 | PredicateKind::ConstEvaluatable(..)
1208 | PredicateKind::ConstEquate(..)
1209 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1214 /// Represents the bounds declared on a particular set of type
1215 /// parameters. Should eventually be generalized into a flag list of
1216 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
1217 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1218 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1219 /// the `GenericPredicates` are expressed in terms of the bound type
1220 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1221 /// represented a set of bounds for some particular instantiation,
1222 /// meaning that the generic parameters have been substituted with
1226 /// ```ignore (illustrative)
1227 /// struct Foo<T, U: Bar<T>> { ... }
1229 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1230 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1231 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1232 /// [usize:Bar<isize>]]`.
1233 #[derive(Clone, Debug, TypeFoldable, TypeVisitable)]
1234 pub struct InstantiatedPredicates<'tcx> {
1235 pub predicates: Vec<Predicate<'tcx>>,
1236 pub spans: Vec<Span>,
1239 impl<'tcx> InstantiatedPredicates<'tcx> {
1240 pub fn empty() -> InstantiatedPredicates<'tcx> {
1241 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1244 pub fn is_empty(&self) -> bool {
1245 self.predicates.is_empty()
1249 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable, Lift)]
1250 #[derive(TypeFoldable, TypeVisitable)]
1251 pub struct OpaqueTypeKey<'tcx> {
1252 pub def_id: LocalDefId,
1253 pub substs: SubstsRef<'tcx>,
1256 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, HashStable, TyEncodable, TyDecodable)]
1257 pub struct OpaqueHiddenType<'tcx> {
1258 /// The span of this particular definition of the opaque type. So
1261 /// ```ignore (incomplete snippet)
1262 /// type Foo = impl Baz;
1263 /// fn bar() -> Foo {
1264 /// // ^^^ This is the span we are looking for!
1268 /// In cases where the fn returns `(impl Trait, impl Trait)` or
1269 /// other such combinations, the result is currently
1270 /// over-approximated, but better than nothing.
1273 /// The type variable that represents the value of the opaque type
1274 /// that we require. In other words, after we compile this function,
1275 /// we will be created a constraint like:
1276 /// ```ignore (pseudo-rust)
1279 /// where `?C` is the value of this type variable. =) It may
1280 /// naturally refer to the type and lifetime parameters in scope
1281 /// in this function, though ultimately it should only reference
1282 /// those that are arguments to `Foo` in the constraint above. (In
1283 /// other words, `?C` should not include `'b`, even though it's a
1284 /// lifetime parameter on `foo`.)
1288 impl<'tcx> OpaqueHiddenType<'tcx> {
1289 pub fn report_mismatch(&self, other: &Self, tcx: TyCtxt<'tcx>) {
1290 // Found different concrete types for the opaque type.
1291 let sub_diag = if self.span == other.span {
1292 TypeMismatchReason::ConflictType { span: self.span }
1294 TypeMismatchReason::PreviousUse { span: self.span }
1296 tcx.sess.emit_err(OpaqueHiddenTypeMismatch {
1299 other_span: other.span,
1305 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1306 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1307 /// regions/types/consts within the same universe simply have an unknown relationship to one
1309 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
1310 #[derive(HashStable, TyEncodable, TyDecodable)]
1311 pub struct Placeholder<T> {
1312 pub universe: UniverseIndex,
1316 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1318 pub type PlaceholderType = Placeholder<BoundVar>;
1320 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1321 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1322 pub struct BoundConst<'tcx> {
1327 pub type PlaceholderConst<'tcx> = Placeholder<BoundVar>;
1329 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1330 /// the `DefId` of the generic parameter it instantiates.
1332 /// This is used to avoid calls to `type_of` for const arguments during typeck
1333 /// which cause cycle errors.
1338 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1339 /// // ^ const parameter
1343 /// fn foo<const M: u8>(&self) -> usize { 42 }
1344 /// // ^ const parameter
1349 /// let _b = a.foo::<{ 3 + 7 }>();
1350 /// // ^^^^^^^^^ const argument
1354 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1355 /// which `foo` is used until we know the type of `a`.
1357 /// We only know the type of `a` once we are inside of `typeck(main)`.
1358 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1359 /// requires us to evaluate the const argument.
1361 /// To evaluate that const argument we need to know its type,
1362 /// which we would get using `type_of(const_arg)`. This requires us to
1363 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1364 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1365 /// which results in a cycle.
1367 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1369 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1370 /// already resolved `foo` so we know which const parameter this argument instantiates.
1371 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1372 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1373 /// trivial to compute.
1375 /// If we now want to use that constant in a place which potentially needs its type
1376 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1377 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1378 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1379 /// to get the type of `did`.
1380 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift, TyEncodable, TyDecodable)]
1381 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1382 #[derive(Hash, HashStable)]
1383 pub struct WithOptConstParam<T> {
1385 /// The `DefId` of the corresponding generic parameter in case `did` is
1386 /// a const argument.
1388 /// Note that even if `did` is a const argument, this may still be `None`.
1389 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1390 /// to potentially update `param_did` in the case it is `None`.
1391 pub const_param_did: Option<DefId>,
1394 impl<T> WithOptConstParam<T> {
1395 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1397 pub fn unknown(did: T) -> WithOptConstParam<T> {
1398 WithOptConstParam { did, const_param_did: None }
1402 impl WithOptConstParam<LocalDefId> {
1403 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1404 /// `None` otherwise.
1406 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1407 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1410 /// In case `self` is unknown but `self.did` is a const argument, this returns
1411 /// a `WithOptConstParam` with the correct `const_param_did`.
1413 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1414 if self.const_param_did.is_none() {
1415 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1416 return Some(WithOptConstParam { did: self.did, const_param_did });
1423 pub fn to_global(self) -> WithOptConstParam<DefId> {
1424 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1427 pub fn def_id_for_type_of(self) -> DefId {
1428 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1432 impl WithOptConstParam<DefId> {
1433 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1436 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1439 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1440 if let Some(param_did) = self.const_param_did {
1441 if let Some(did) = self.did.as_local() {
1442 return Some((did, param_did));
1449 pub fn is_local(self) -> bool {
1453 pub fn def_id_for_type_of(self) -> DefId {
1454 self.const_param_did.unwrap_or(self.did)
1458 /// When type checking, we use the `ParamEnv` to track
1459 /// details about the set of where-clauses that are in scope at this
1460 /// particular point.
1461 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1462 pub struct ParamEnv<'tcx> {
1463 /// This packs both caller bounds and the reveal enum into one pointer.
1465 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1466 /// basically the set of bounds on the in-scope type parameters, translated
1467 /// into `Obligation`s, and elaborated and normalized.
1469 /// Use the `caller_bounds()` method to access.
1471 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1472 /// want `Reveal::All`.
1474 /// Note: This is packed, use the reveal() method to access it.
1475 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
1478 #[derive(Copy, Clone)]
1480 reveal: traits::Reveal,
1481 constness: hir::Constness,
1484 unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
1485 const BITS: usize = 2;
1487 fn into_usize(self) -> usize {
1489 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
1490 Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
1491 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
1492 Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
1496 unsafe fn from_usize(ptr: usize) -> Self {
1498 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1499 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
1500 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
1501 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
1502 _ => std::hint::unreachable_unchecked(),
1507 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1508 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1509 f.debug_struct("ParamEnv")
1510 .field("caller_bounds", &self.caller_bounds())
1511 .field("reveal", &self.reveal())
1512 .field("constness", &self.constness())
1517 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1518 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1519 self.caller_bounds().hash_stable(hcx, hasher);
1520 self.reveal().hash_stable(hcx, hasher);
1521 self.constness().hash_stable(hcx, hasher);
1525 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1526 fn try_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
1529 ) -> Result<Self, F::Error> {
1531 self.caller_bounds().try_fold_with(folder)?,
1532 self.reveal().try_fold_with(folder)?,
1538 impl<'tcx> TypeVisitable<'tcx> for ParamEnv<'tcx> {
1539 fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1540 self.caller_bounds().visit_with(visitor)?;
1541 self.reveal().visit_with(visitor)
1545 impl<'tcx> ParamEnv<'tcx> {
1546 /// Construct a trait environment suitable for contexts where
1547 /// there are no where-clauses in scope. Hidden types (like `impl
1548 /// Trait`) are left hidden, so this is suitable for ordinary
1551 pub fn empty() -> Self {
1552 Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
1556 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1557 self.packed.pointer()
1561 pub fn reveal(self) -> traits::Reveal {
1562 self.packed.tag().reveal
1566 pub fn constness(self) -> hir::Constness {
1567 self.packed.tag().constness
1571 pub fn is_const(self) -> bool {
1572 self.packed.tag().constness == hir::Constness::Const
1575 /// Construct a trait environment with no where-clauses in scope
1576 /// where the values of all `impl Trait` and other hidden types
1577 /// are revealed. This is suitable for monomorphized, post-typeck
1578 /// environments like codegen or doing optimizations.
1580 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1581 /// or invoke `param_env.with_reveal_all()`.
1583 pub fn reveal_all() -> Self {
1584 Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
1587 /// Construct a trait environment with the given set of predicates.
1590 caller_bounds: &'tcx List<Predicate<'tcx>>,
1592 constness: hir::Constness,
1594 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
1597 pub fn with_user_facing(mut self) -> Self {
1598 self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
1603 pub fn with_constness(mut self, constness: hir::Constness) -> Self {
1604 self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
1609 pub fn with_const(mut self) -> Self {
1610 self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
1615 pub fn without_const(mut self) -> Self {
1616 self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
1621 pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
1622 *self = self.with_constness(constness.and(self.constness()))
1625 /// Returns a new parameter environment with the same clauses, but
1626 /// which "reveals" the true results of projections in all cases
1627 /// (even for associated types that are specializable). This is
1628 /// the desired behavior during codegen and certain other special
1629 /// contexts; normally though we want to use `Reveal::UserFacing`,
1630 /// which is the default.
1631 /// All opaque types in the caller_bounds of the `ParamEnv`
1632 /// will be normalized to their underlying types.
1633 /// See PR #65989 and issue #65918 for more details
1634 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1635 if self.packed.tag().reveal == traits::Reveal::All {
1640 tcx.normalize_opaque_types(self.caller_bounds()),
1646 /// Returns this same environment but with no caller bounds.
1648 pub fn without_caller_bounds(self) -> Self {
1649 Self::new(List::empty(), self.reveal(), self.constness())
1652 /// Creates a suitable environment in which to perform trait
1653 /// queries on the given value. When type-checking, this is simply
1654 /// the pair of the environment plus value. But when reveal is set to
1655 /// All, then if `value` does not reference any type parameters, we will
1656 /// pair it with the empty environment. This improves caching and is generally
1659 /// N.B., we preserve the environment when type-checking because it
1660 /// is possible for the user to have wacky where-clauses like
1661 /// `where Box<u32>: Copy`, which are clearly never
1662 /// satisfiable. We generally want to behave as if they were true,
1663 /// although the surrounding function is never reachable.
1664 pub fn and<T: TypeVisitable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1665 match self.reveal() {
1666 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1669 if value.is_global() {
1670 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1672 ParamEnvAnd { param_env: self, value }
1679 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1680 // the constness of trait bounds is being propagated correctly.
1681 impl<'tcx> PolyTraitRef<'tcx> {
1683 pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
1684 self.map_bound(|trait_ref| ty::TraitPredicate {
1687 polarity: ty::ImplPolarity::Positive,
1692 pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
1693 self.with_constness(BoundConstness::NotConst)
1697 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable, TypeVisitable)]
1698 #[derive(HashStable, Lift)]
1699 pub struct ParamEnvAnd<'tcx, T> {
1700 pub param_env: ParamEnv<'tcx>,
1704 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1705 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1706 (self.param_env, self.value)
1710 pub fn without_const(mut self) -> Self {
1711 self.param_env = self.param_env.without_const();
1716 #[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
1717 pub struct Destructor {
1718 /// The `DefId` of the destructor method
1720 /// The constness of the destructor method
1721 pub constness: hir::Constness,
1725 #[derive(HashStable, TyEncodable, TyDecodable)]
1726 pub struct VariantFlags: u32 {
1727 const NO_VARIANT_FLAGS = 0;
1728 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1729 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1730 /// Indicates whether this variant was obtained as part of recovering from
1731 /// a syntactic error. May be incomplete or bogus.
1732 const IS_RECOVERED = 1 << 1;
1736 /// Definition of a variant -- a struct's fields or an enum variant.
1737 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1738 pub struct VariantDef {
1739 /// `DefId` that identifies the variant itself.
1740 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1742 /// `DefId` that identifies the variant's constructor.
1743 /// If this variant is a struct variant, then this is `None`.
1744 pub ctor_def_id: Option<DefId>,
1745 /// Variant or struct name.
1747 /// Discriminant of this variant.
1748 pub discr: VariantDiscr,
1749 /// Fields of this variant.
1750 pub fields: Vec<FieldDef>,
1751 /// Type of constructor of variant.
1752 pub ctor_kind: CtorKind,
1753 /// Flags of the variant (e.g. is field list non-exhaustive)?
1754 flags: VariantFlags,
1758 /// Creates a new `VariantDef`.
1760 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1761 /// represents an enum variant).
1763 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1764 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1766 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1767 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1768 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1769 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1770 /// built-in trait), and we do not want to load attributes twice.
1772 /// If someone speeds up attribute loading to not be a performance concern, they can
1773 /// remove this hack and use the constructor `DefId` everywhere.
1776 variant_did: Option<DefId>,
1777 ctor_def_id: Option<DefId>,
1778 discr: VariantDiscr,
1779 fields: Vec<FieldDef>,
1780 ctor_kind: CtorKind,
1784 is_field_list_non_exhaustive: bool,
1787 "VariantDef::new(name = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1788 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1789 name, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1792 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1793 if is_field_list_non_exhaustive {
1794 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1798 flags |= VariantFlags::IS_RECOVERED;
1802 def_id: variant_did.unwrap_or(parent_did),
1812 /// Is this field list non-exhaustive?
1814 pub fn is_field_list_non_exhaustive(&self) -> bool {
1815 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1818 /// Was this variant obtained as part of recovering from a syntactic error?
1820 pub fn is_recovered(&self) -> bool {
1821 self.flags.intersects(VariantFlags::IS_RECOVERED)
1824 /// Computes the `Ident` of this variant by looking up the `Span`
1825 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1826 Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1830 impl PartialEq for VariantDef {
1832 fn eq(&self, other: &Self) -> bool {
1833 // There should be only one `VariantDef` for each `def_id`, therefore
1834 // it is fine to implement `PartialEq` only based on `def_id`.
1836 // Below, we exhaustively destructure `self` and `other` so that if the
1837 // definition of `VariantDef` changes, a compile-error will be produced,
1838 // reminding us to revisit this assumption.
1860 lhs_def_id == rhs_def_id
1864 impl Eq for VariantDef {}
1866 impl Hash for VariantDef {
1868 fn hash<H: Hasher>(&self, s: &mut H) {
1869 // There should be only one `VariantDef` for each `def_id`, therefore
1870 // it is fine to implement `Hash` only based on `def_id`.
1872 // Below, we exhaustively destructure `self` so that if the definition
1873 // of `VariantDef` changes, a compile-error will be produced, reminding
1874 // us to revisit this assumption.
1876 let Self { def_id, ctor_def_id: _, name: _, discr: _, fields: _, ctor_kind: _, flags: _ } =
1883 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1884 pub enum VariantDiscr {
1885 /// Explicit value for this variant, i.e., `X = 123`.
1886 /// The `DefId` corresponds to the embedded constant.
1889 /// The previous variant's discriminant plus one.
1890 /// For efficiency reasons, the distance from the
1891 /// last `Explicit` discriminant is being stored,
1892 /// or `0` for the first variant, if it has none.
1896 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1897 pub struct FieldDef {
1900 pub vis: Visibility<DefId>,
1903 impl PartialEq for FieldDef {
1905 fn eq(&self, other: &Self) -> bool {
1906 // There should be only one `FieldDef` for each `did`, therefore it is
1907 // fine to implement `PartialEq` only based on `did`.
1909 // Below, we exhaustively destructure `self` so that if the definition
1910 // of `FieldDef` changes, a compile-error will be produced, reminding
1911 // us to revisit this assumption.
1913 let Self { did: lhs_did, name: _, vis: _ } = &self;
1915 let Self { did: rhs_did, name: _, vis: _ } = other;
1921 impl Eq for FieldDef {}
1923 impl Hash for FieldDef {
1925 fn hash<H: Hasher>(&self, s: &mut H) {
1926 // There should be only one `FieldDef` for each `did`, therefore it is
1927 // fine to implement `Hash` only based on `did`.
1929 // Below, we exhaustively destructure `self` so that if the definition
1930 // of `FieldDef` changes, a compile-error will be produced, reminding
1931 // us to revisit this assumption.
1933 let Self { did, name: _, vis: _ } = &self;
1940 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1941 pub struct ReprFlags: u8 {
1942 const IS_C = 1 << 0;
1943 const IS_SIMD = 1 << 1;
1944 const IS_TRANSPARENT = 1 << 2;
1945 // Internal only for now. If true, don't reorder fields.
1946 const IS_LINEAR = 1 << 3;
1947 // If true, the type's layout can be randomized using
1948 // the seed stored in `ReprOptions.layout_seed`
1949 const RANDOMIZE_LAYOUT = 1 << 4;
1950 // Any of these flags being set prevent field reordering optimisation.
1951 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
1952 | ReprFlags::IS_SIMD.bits
1953 | ReprFlags::IS_LINEAR.bits;
1957 /// Represents the repr options provided by the user,
1958 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
1959 pub struct ReprOptions {
1960 pub int: Option<attr::IntType>,
1961 pub align: Option<Align>,
1962 pub pack: Option<Align>,
1963 pub flags: ReprFlags,
1964 /// The seed to be used for randomizing a type's layout
1966 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
1967 /// be the "most accurate" hash as it'd encompass the item and crate
1968 /// hash without loss, but it does pay the price of being larger.
1969 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
1970 /// purposes (primarily `-Z randomize-layout`)
1971 pub field_shuffle_seed: u64,
1975 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1976 let mut flags = ReprFlags::empty();
1977 let mut size = None;
1978 let mut max_align: Option<Align> = None;
1979 let mut min_pack: Option<Align> = None;
1981 // Generate a deterministically-derived seed from the item's path hash
1982 // to allow for cross-crate compilation to actually work
1983 let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
1985 // If the user defined a custom seed for layout randomization, xor the item's
1986 // path hash with the user defined seed, this will allowing determinism while
1987 // still allowing users to further randomize layout generation for e.g. fuzzing
1988 if let Some(user_seed) = tcx.sess.opts.unstable_opts.layout_seed {
1989 field_shuffle_seed ^= user_seed;
1992 for attr in tcx.get_attrs(did, sym::repr) {
1993 for r in attr::parse_repr_attr(&tcx.sess, attr) {
1994 flags.insert(match r {
1995 attr::ReprC => ReprFlags::IS_C,
1996 attr::ReprPacked(pack) => {
1997 let pack = Align::from_bytes(pack as u64).unwrap();
1998 min_pack = Some(if let Some(min_pack) = min_pack {
2005 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2006 attr::ReprSimd => ReprFlags::IS_SIMD,
2007 attr::ReprInt(i) => {
2011 attr::ReprAlign(align) => {
2012 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2019 // If `-Z randomize-layout` was enabled for the type definition then we can
2020 // consider performing layout randomization
2021 if tcx.sess.opts.unstable_opts.randomize_layout {
2022 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
2025 // This is here instead of layout because the choice must make it into metadata.
2026 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2027 flags.insert(ReprFlags::IS_LINEAR);
2030 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
2034 pub fn simd(&self) -> bool {
2035 self.flags.contains(ReprFlags::IS_SIMD)
2039 pub fn c(&self) -> bool {
2040 self.flags.contains(ReprFlags::IS_C)
2044 pub fn packed(&self) -> bool {
2049 pub fn transparent(&self) -> bool {
2050 self.flags.contains(ReprFlags::IS_TRANSPARENT)
2054 pub fn linear(&self) -> bool {
2055 self.flags.contains(ReprFlags::IS_LINEAR)
2058 /// Returns the discriminant type, given these `repr` options.
2059 /// This must only be called on enums!
2060 pub fn discr_type(&self) -> attr::IntType {
2061 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2064 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2065 /// layout" optimizations, such as representing `Foo<&T>` as a
2067 pub fn inhibit_enum_layout_opt(&self) -> bool {
2068 self.c() || self.int.is_some()
2071 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2072 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2073 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2074 if let Some(pack) = self.pack {
2075 if pack.bytes() == 1 {
2080 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2083 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
2084 /// was enabled for its declaration crate
2085 pub fn can_randomize_type_layout(&self) -> bool {
2086 !self.inhibit_struct_field_reordering_opt()
2087 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
2090 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2091 pub fn inhibit_union_abi_opt(&self) -> bool {
2096 impl<'tcx> FieldDef {
2097 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
2098 /// typically obtained via the second field of [`TyKind::Adt`].
2099 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2100 tcx.bound_type_of(self.did).subst(tcx, subst)
2103 /// Computes the `Ident` of this variant by looking up the `Span`
2104 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
2105 Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
2109 pub type Attributes<'tcx> = impl Iterator<Item = &'tcx ast::Attribute>;
2110 #[derive(Debug, PartialEq, Eq)]
2111 pub enum ImplOverlapKind {
2112 /// These impls are always allowed to overlap.
2114 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
2117 /// These impls are allowed to overlap, but that raises
2118 /// an issue #33140 future-compatibility warning.
2120 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2121 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2123 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2124 /// that difference, making what reduces to the following set of impls:
2126 /// ```compile_fail,(E0119)
2128 /// impl Trait for dyn Send + Sync {}
2129 /// impl Trait for dyn Sync + Send {}
2132 /// Obviously, once we made these types be identical, that code causes a coherence
2133 /// error and a fairly big headache for us. However, luckily for us, the trait
2134 /// `Trait` used in this case is basically a marker trait, and therefore having
2135 /// overlapping impls for it is sound.
2137 /// To handle this, we basically regard the trait as a marker trait, with an additional
2138 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2139 /// it has the following restrictions:
2141 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2143 /// 2. The trait-ref of both impls must be equal.
2144 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2146 /// 4. Neither of the impls can have any where-clauses.
2148 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2152 impl<'tcx> TyCtxt<'tcx> {
2153 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
2154 self.typeck(self.hir().body_owner_def_id(body))
2157 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
2158 self.associated_items(id)
2159 .in_definition_order()
2160 .filter(move |item| item.kind == AssocKind::Fn && item.defaultness(self).has_value())
2163 /// Look up the name of a definition across crates. This does not look at HIR.
2164 pub fn opt_item_name(self, def_id: DefId) -> Option<Symbol> {
2165 if let Some(cnum) = def_id.as_crate_root() {
2166 Some(self.crate_name(cnum))
2168 let def_key = self.def_key(def_id);
2169 match def_key.disambiguated_data.data {
2170 // The name of a constructor is that of its parent.
2171 rustc_hir::definitions::DefPathData::Ctor => self
2172 .opt_item_name(DefId { krate: def_id.krate, index: def_key.parent.unwrap() }),
2173 // The name of opaque types only exists in HIR.
2174 rustc_hir::definitions::DefPathData::ImplTrait
2175 if let Some(def_id) = def_id.as_local() =>
2176 self.hir().opt_name(self.hir().local_def_id_to_hir_id(def_id)),
2177 _ => def_key.get_opt_name(),
2182 /// Look up the name of a definition across crates. This does not look at HIR.
2184 /// This method will ICE if the corresponding item does not have a name. In these cases, use
2185 /// [`opt_item_name`] instead.
2187 /// [`opt_item_name`]: Self::opt_item_name
2188 pub fn item_name(self, id: DefId) -> Symbol {
2189 self.opt_item_name(id).unwrap_or_else(|| {
2190 bug!("item_name: no name for {:?}", self.def_path(id));
2194 /// Look up the name and span of a definition.
2196 /// See [`item_name`][Self::item_name] for more information.
2197 pub fn opt_item_ident(self, def_id: DefId) -> Option<Ident> {
2198 let def = self.opt_item_name(def_id)?;
2201 .and_then(|id| self.def_ident_span(id))
2202 .unwrap_or(rustc_span::DUMMY_SP);
2203 Some(Ident::new(def, span))
2206 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2207 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2208 Some(self.associated_item(def_id))
2214 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
2215 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
2218 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2222 .position(|field| self.hygienic_eq(ident, field.ident(self), variant.def_id))
2225 /// Returns `true` if the impls are the same polarity and the trait either
2226 /// has no items or is annotated `#[marker]` and prevents item overrides.
2227 pub fn impls_are_allowed_to_overlap(
2231 ) -> Option<ImplOverlapKind> {
2232 // If either trait impl references an error, they're allowed to overlap,
2233 // as one of them essentially doesn't exist.
2234 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2235 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2237 return Some(ImplOverlapKind::Permitted { marker: false });
2240 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2241 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2242 // `#[rustc_reservation_impl]` impls don't overlap with anything
2244 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2247 return Some(ImplOverlapKind::Permitted { marker: false });
2249 (ImplPolarity::Positive, ImplPolarity::Negative)
2250 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2251 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2253 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2258 (ImplPolarity::Positive, ImplPolarity::Positive)
2259 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2262 let is_marker_overlap = {
2263 let is_marker_impl = |def_id: DefId| -> bool {
2264 let trait_ref = self.impl_trait_ref(def_id);
2265 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2267 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2270 if is_marker_overlap {
2272 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2275 Some(ImplOverlapKind::Permitted { marker: true })
2277 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2278 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2279 if self_ty1 == self_ty2 {
2281 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2284 return Some(ImplOverlapKind::Issue33140);
2287 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2288 def_id1, def_id2, self_ty1, self_ty2
2294 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2299 /// Returns `ty::VariantDef` if `res` refers to a struct,
2300 /// or variant or their constructors, panics otherwise.
2301 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2303 Res::Def(DefKind::Variant, did) => {
2304 let enum_did = self.parent(did);
2305 self.adt_def(enum_did).variant_with_id(did)
2307 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2308 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2309 let variant_did = self.parent(variant_ctor_did);
2310 let enum_did = self.parent(variant_did);
2311 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2313 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2314 let struct_did = self.parent(ctor_did);
2315 self.adt_def(struct_did).non_enum_variant()
2317 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2321 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2322 #[instrument(skip(self), level = "debug")]
2323 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2325 ty::InstanceDef::Item(def) => {
2326 debug!("calling def_kind on def: {:?}", def);
2327 let def_kind = self.def_kind(def.did);
2328 debug!("returned from def_kind: {:?}", def_kind);
2331 | DefKind::Static(..)
2332 | DefKind::AssocConst
2334 | DefKind::AnonConst
2335 | DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
2336 // If the caller wants `mir_for_ctfe` of a function they should not be using
2337 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2339 assert_eq!(def.const_param_did, None);
2340 self.optimized_mir(def.did)
2344 ty::InstanceDef::VTableShim(..)
2345 | ty::InstanceDef::ReifyShim(..)
2346 | ty::InstanceDef::Intrinsic(..)
2347 | ty::InstanceDef::FnPtrShim(..)
2348 | ty::InstanceDef::Virtual(..)
2349 | ty::InstanceDef::ClosureOnceShim { .. }
2350 | ty::InstanceDef::DropGlue(..)
2351 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2355 // FIXME(@lcnr): Remove this function.
2356 pub fn get_attrs_unchecked(self, did: DefId) -> &'tcx [ast::Attribute] {
2357 if let Some(did) = did.as_local() {
2358 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2360 self.item_attrs(did)
2364 /// Gets all attributes with the given name.
2365 pub fn get_attrs(self, did: DefId, attr: Symbol) -> ty::Attributes<'tcx> {
2366 let filter_fn = move |a: &&ast::Attribute| a.has_name(attr);
2367 if let Some(did) = did.as_local() {
2368 self.hir().attrs(self.hir().local_def_id_to_hir_id(did)).iter().filter(filter_fn)
2369 } else if cfg!(debug_assertions) && rustc_feature::is_builtin_only_local(attr) {
2370 bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr);
2372 self.item_attrs(did).iter().filter(filter_fn)
2376 pub fn get_attr(self, did: DefId, attr: Symbol) -> Option<&'tcx ast::Attribute> {
2377 if cfg!(debug_assertions) && !rustc_feature::is_valid_for_get_attr(attr) {
2378 bug!("get_attr: unexpected called with DefId `{:?}`, attr `{:?}`", did, attr);
2380 self.get_attrs(did, attr).next()
2384 /// Determines whether an item is annotated with an attribute.
2385 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2386 if cfg!(debug_assertions) && !did.is_local() && rustc_feature::is_builtin_only_local(attr) {
2387 bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr);
2389 self.get_attrs(did, attr).next().is_some()
2393 /// Returns `true` if this is an `auto trait`.
2394 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2395 self.trait_def(trait_def_id).has_auto_impl
2398 /// Returns layout of a generator. Layout might be unavailable if the
2399 /// generator is tainted by errors.
2400 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2401 self.optimized_mir(def_id).generator_layout()
2404 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2405 /// If it implements no trait, returns `None`.
2406 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2407 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2410 /// If the given `DefId` describes an item belonging to a trait,
2411 /// returns the `DefId` of the trait that the trait item belongs to;
2412 /// otherwise, returns `None`.
2413 pub fn trait_of_item(self, def_id: DefId) -> Option<DefId> {
2414 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2415 let parent = self.parent(def_id);
2416 if let DefKind::Trait | DefKind::TraitAlias = self.def_kind(parent) {
2417 return Some(parent);
2423 /// If the given `DefId` describes a method belonging to an impl, returns the
2424 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2425 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2426 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2427 let parent = self.parent(def_id);
2428 if let DefKind::Impl = self.def_kind(parent) {
2429 return Some(parent);
2435 /// If the given `DefId` belongs to a trait that was automatically derived, returns `true`.
2436 pub fn is_builtin_derive(self, def_id: DefId) -> bool {
2437 self.has_attr(def_id, sym::automatically_derived)
2440 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2441 /// with the name of the crate containing the impl.
2442 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2443 if let Some(impl_did) = impl_did.as_local() {
2444 Ok(self.def_span(impl_did))
2446 Err(self.crate_name(impl_did.krate))
2450 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2451 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2452 /// definition's parent/scope to perform comparison.
2453 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2454 // We could use `Ident::eq` here, but we deliberately don't. The name
2455 // comparison fails frequently, and we want to avoid the expensive
2456 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2457 use_name.name == def_name.name
2461 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2464 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2465 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2469 pub fn adjust_ident_and_get_scope(
2474 ) -> (Ident, DefId) {
2477 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2478 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2479 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2483 /// Returns `true` if the debuginfo for `span` should be collapsed to the outermost expansion
2484 /// site. Only applies when `Span` is the result of macro expansion.
2486 /// - If the `collapse_debuginfo` feature is enabled then debuginfo is not collapsed by default
2487 /// and only when a macro definition is annotated with `#[collapse_debuginfo]`.
2488 /// - If `collapse_debuginfo` is not enabled, then debuginfo is collapsed by default.
2490 /// When `-Zdebug-macros` is provided then debuginfo will never be collapsed.
2491 pub fn should_collapse_debuginfo(self, span: Span) -> bool {
2492 !self.sess.opts.unstable_opts.debug_macros
2493 && if self.features().collapse_debuginfo {
2494 span.in_macro_expansion_with_collapse_debuginfo()
2496 span.from_expansion()
2500 pub fn is_object_safe(self, key: DefId) -> bool {
2501 self.object_safety_violations(key).is_empty()
2505 pub fn is_const_fn_raw(self, def_id: DefId) -> bool {
2506 matches!(self.def_kind(def_id), DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..))
2507 && self.constness(def_id) == hir::Constness::Const
2511 pub fn is_const_default_method(self, def_id: DefId) -> bool {
2512 matches!(self.trait_of_item(def_id), Some(trait_id) if self.has_attr(trait_id, sym::const_trait))
2515 pub fn impl_trait_in_trait_parent(self, mut def_id: DefId) -> DefId {
2516 while let def_kind = self.def_kind(def_id) && def_kind != DefKind::AssocFn {
2517 debug_assert_eq!(def_kind, DefKind::ImplTraitPlaceholder);
2518 def_id = self.parent(def_id);
2524 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
2525 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
2526 let def_id = def_id.as_local()?;
2527 if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) {
2528 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2529 return match opaque_ty.origin {
2530 hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
2533 hir::OpaqueTyOrigin::TyAlias => None,
2540 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2542 ast::IntTy::Isize => IntTy::Isize,
2543 ast::IntTy::I8 => IntTy::I8,
2544 ast::IntTy::I16 => IntTy::I16,
2545 ast::IntTy::I32 => IntTy::I32,
2546 ast::IntTy::I64 => IntTy::I64,
2547 ast::IntTy::I128 => IntTy::I128,
2551 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2553 ast::UintTy::Usize => UintTy::Usize,
2554 ast::UintTy::U8 => UintTy::U8,
2555 ast::UintTy::U16 => UintTy::U16,
2556 ast::UintTy::U32 => UintTy::U32,
2557 ast::UintTy::U64 => UintTy::U64,
2558 ast::UintTy::U128 => UintTy::U128,
2562 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2564 ast::FloatTy::F32 => FloatTy::F32,
2565 ast::FloatTy::F64 => FloatTy::F64,
2569 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2571 IntTy::Isize => ast::IntTy::Isize,
2572 IntTy::I8 => ast::IntTy::I8,
2573 IntTy::I16 => ast::IntTy::I16,
2574 IntTy::I32 => ast::IntTy::I32,
2575 IntTy::I64 => ast::IntTy::I64,
2576 IntTy::I128 => ast::IntTy::I128,
2580 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2582 UintTy::Usize => ast::UintTy::Usize,
2583 UintTy::U8 => ast::UintTy::U8,
2584 UintTy::U16 => ast::UintTy::U16,
2585 UintTy::U32 => ast::UintTy::U32,
2586 UintTy::U64 => ast::UintTy::U64,
2587 UintTy::U128 => ast::UintTy::U128,
2591 pub fn provide(providers: &mut ty::query::Providers) {
2592 closure::provide(providers);
2593 context::provide(providers);
2594 erase_regions::provide(providers);
2595 util::provide(providers);
2596 print::provide(providers);
2597 super::util::bug::provide(providers);
2598 super::middle::provide(providers);
2599 *providers = ty::query::Providers {
2600 trait_impls_of: trait_def::trait_impls_of_provider,
2601 incoherent_impls: trait_def::incoherent_impls_provider,
2602 type_uninhabited_from: inhabitedness::type_uninhabited_from,
2603 const_param_default: consts::const_param_default,
2604 vtable_allocation: vtable::vtable_allocation_provider,
2609 /// A map for the local crate mapping each type to a vector of its
2610 /// inherent impls. This is not meant to be used outside of coherence;
2611 /// rather, you should request the vector for a specific type via
2612 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2613 /// (constructing this map requires touching the entire crate).
2614 #[derive(Clone, Debug, Default, HashStable)]
2615 pub struct CrateInherentImpls {
2616 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2617 pub incoherent_impls: FxHashMap<SimplifiedType, Vec<LocalDefId>>,
2620 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2621 pub struct SymbolName<'tcx> {
2622 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2623 pub name: &'tcx str,
2626 impl<'tcx> SymbolName<'tcx> {
2627 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2629 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2634 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2635 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2636 fmt::Display::fmt(&self.name, fmt)
2640 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2641 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2642 fmt::Display::fmt(&self.name, fmt)
2646 #[derive(Debug, Default, Copy, Clone)]
2647 pub struct FoundRelationships {
2648 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2649 /// obligation, where:
2651 /// * `Foo` is not `Sized`
2652 /// * `(): Foo` may be satisfied
2653 pub self_in_trait: bool,
2654 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2655 /// _>::AssocType = ?T`
2659 /// The constituent parts of a type level constant of kind ADT or array.
2660 #[derive(Copy, Clone, Debug, HashStable)]
2661 pub struct DestructuredConst<'tcx> {
2662 pub variant: Option<VariantIdx>,
2663 pub fields: &'tcx [ty::Const<'tcx>],
2666 // Some types are used a lot. Make sure they don't unintentionally get bigger.
2667 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
2670 use rustc_data_structures::static_assert_size;
2671 // These are in alphabetical order, which is easy to maintain.
2672 static_assert_size!(PredicateS<'_>, 48);
2673 static_assert_size!(TyS<'_>, 40);
2674 static_assert_size!(WithStableHash<TyS<'_>>, 56);