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::EffectiveVisibilities;
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;
29 use hir::OpaqueTyOrigin;
31 use rustc_ast::node_id::NodeMap;
32 use rustc_attr as attr;
33 use rustc_data_structures::fingerprint::Fingerprint;
34 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
35 use rustc_data_structures::intern::{Interned, WithStableHash};
36 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
37 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
39 use rustc_hir::def::{CtorKind, CtorOf, DefKind, LifetimeRes, Res};
40 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap};
41 use rustc_hir::definitions::Definitions;
43 use rustc_index::vec::IndexVec;
44 use rustc_macros::HashStable;
45 use rustc_query_system::ich::StableHashingContext;
46 use rustc_serialize::{Decodable, Encodable};
47 use rustc_session::cstore::CrateStoreDyn;
48 use rustc_span::hygiene::MacroKind;
49 use rustc_span::symbol::{kw, sym, Ident, Symbol};
50 use rustc_span::{ExpnId, Span};
51 use rustc_target::abi::{Align, VariantIdx};
56 use std::hash::{Hash, Hasher};
57 use std::marker::PhantomData;
59 use std::num::NonZeroUsize;
60 use std::ops::ControlFlow;
63 pub use crate::ty::diagnostics::*;
64 pub use rustc_type_ir::DynKind::*;
65 pub use rustc_type_ir::InferTy::*;
66 pub use rustc_type_ir::RegionKind::*;
67 pub use rustc_type_ir::TyKind::*;
68 pub use rustc_type_ir::*;
70 pub use self::binding::BindingMode;
71 pub use self::binding::BindingMode::*;
72 pub use self::closure::{
73 is_ancestor_or_same_capture, place_to_string_for_capture, BorrowKind, CaptureInfo,
74 CapturedPlace, ClosureKind, MinCaptureInformationMap, MinCaptureList,
75 RootVariableMinCaptureList, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath,
78 pub use self::consts::{
79 Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, UnevaluatedConst, ValTree,
81 pub use self::context::{
82 tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
83 CtxtInterners, DeducedParamAttrs, FreeRegionInfo, GeneratorDiagnosticData,
84 GeneratorInteriorTypeCause, GlobalCtxt, Lift, OnDiskCache, TyCtxt, TypeckResults, UserType,
85 UserTypeAnnotationIndex,
87 pub use self::instance::{Instance, InstanceDef, ShortInstance};
88 pub use self::list::List;
89 pub use self::parameterized::ParameterizedOverTcx;
90 pub use self::rvalue_scopes::RvalueScopes;
91 pub use self::sty::BoundRegionKind::*;
93 Article, Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar,
94 BoundVariableKind, CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid,
95 EarlyBoundRegion, ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig,
96 FreeRegion, GenSig, GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts,
97 InlineConstSubstsParts, ParamConst, ParamTy, PolyExistentialPredicate,
98 PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig, PolyTraitRef,
99 ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut, UpvarSubsts,
102 pub use self::trait_def::TraitDef;
105 pub mod abstract_const;
114 pub mod inhabitedness;
116 pub mod normalize_erasing_regions;
141 mod structural_impls;
146 pub type RegisteredTools = FxHashSet<Ident>;
148 pub struct ResolverOutputs {
149 pub definitions: Definitions,
150 pub global_ctxt: ResolverGlobalCtxt,
151 pub ast_lowering: ResolverAstLowering,
155 pub struct ResolverGlobalCtxt {
156 pub cstore: Box<CrateStoreDyn>,
157 pub visibilities: FxHashMap<LocalDefId, Visibility>,
158 /// This field is used to decide whether we should make `PRIVATE_IN_PUBLIC` a hard error.
159 pub has_pub_restricted: bool,
160 /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
161 pub expn_that_defined: FxHashMap<LocalDefId, ExpnId>,
162 /// Reference span for definitions.
163 pub source_span: IndexVec<LocalDefId, Span>,
164 pub effective_visibilities: EffectiveVisibilities,
165 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
166 pub maybe_unused_trait_imports: FxIndexSet<LocalDefId>,
167 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
168 pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
169 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
170 /// Extern prelude entries. The value is `true` if the entry was introduced
171 /// via `extern crate` item and not `--extern` option or compiler built-in.
172 pub extern_prelude: FxHashMap<Symbol, bool>,
173 pub main_def: Option<MainDefinition>,
174 pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
175 /// A list of proc macro LocalDefIds, written out in the order in which
176 /// they are declared in the static array generated by proc_macro_harness.
177 pub proc_macros: Vec<LocalDefId>,
178 /// Mapping from ident span to path span for paths that don't exist as written, but that
179 /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
180 pub confused_type_with_std_module: FxHashMap<Span, Span>,
181 pub registered_tools: RegisteredTools,
184 /// Resolutions that should only be used for lowering.
185 /// This struct is meant to be consumed by lowering.
187 pub struct ResolverAstLowering {
188 pub legacy_const_generic_args: FxHashMap<DefId, Option<Vec<usize>>>,
190 /// Resolutions for nodes that have a single resolution.
191 pub partial_res_map: NodeMap<hir::def::PartialRes>,
192 /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
193 pub import_res_map: NodeMap<hir::def::PerNS<Option<Res<ast::NodeId>>>>,
194 /// Resolutions for labels (node IDs of their corresponding blocks or loops).
195 pub label_res_map: NodeMap<ast::NodeId>,
196 /// Resolutions for lifetimes.
197 pub lifetimes_res_map: NodeMap<LifetimeRes>,
198 /// Lifetime parameters that lowering will have to introduce.
199 pub extra_lifetime_params_map: NodeMap<Vec<(Ident, ast::NodeId, LifetimeRes)>>,
201 pub next_node_id: ast::NodeId,
203 pub node_id_to_def_id: FxHashMap<ast::NodeId, LocalDefId>,
204 pub def_id_to_node_id: IndexVec<LocalDefId, ast::NodeId>,
206 pub trait_map: NodeMap<Vec<hir::TraitCandidate>>,
207 /// A small map keeping true kinds of built-in macros that appear to be fn-like on
208 /// the surface (`macro` items in libcore), but are actually attributes or derives.
209 pub builtin_macro_kinds: FxHashMap<LocalDefId, MacroKind>,
212 #[derive(Clone, Copy, Debug)]
213 pub struct MainDefinition {
214 pub res: Res<ast::NodeId>,
219 impl MainDefinition {
220 pub fn opt_fn_def_id(self) -> Option<DefId> {
221 if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
225 /// The "header" of an impl is everything outside the body: a Self type, a trait
226 /// ref (in the case of a trait impl), and a set of predicates (from the
227 /// bounds / where-clauses).
228 #[derive(Clone, Debug, TypeFoldable, TypeVisitable)]
229 pub struct ImplHeader<'tcx> {
230 pub impl_def_id: DefId,
231 pub self_ty: Ty<'tcx>,
232 pub trait_ref: Option<TraitRef<'tcx>>,
233 pub predicates: Vec<Predicate<'tcx>>,
236 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable)]
237 pub enum ImplSubject<'tcx> {
238 Trait(TraitRef<'tcx>),
242 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable, Debug)]
243 #[derive(TypeFoldable, TypeVisitable)]
244 pub enum ImplPolarity {
245 /// `impl Trait for Type`
247 /// `impl !Trait for Type`
249 /// `#[rustc_reservation_impl] impl Trait for Type`
251 /// This is a "stability hack", not a real Rust feature.
252 /// See #64631 for details.
257 /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
258 pub fn flip(&self) -> Option<ImplPolarity> {
260 ImplPolarity::Positive => Some(ImplPolarity::Negative),
261 ImplPolarity::Negative => Some(ImplPolarity::Positive),
262 ImplPolarity::Reservation => None,
267 impl fmt::Display for ImplPolarity {
268 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
270 Self::Positive => f.write_str("positive"),
271 Self::Negative => f.write_str("negative"),
272 Self::Reservation => f.write_str("reservation"),
277 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, Encodable, Decodable, HashStable)]
278 pub enum Visibility<Id = LocalDefId> {
279 /// Visible everywhere (including in other crates).
281 /// Visible only in the given crate-local module.
285 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
286 pub enum BoundConstness {
289 /// `T: ~const Trait`
291 /// Requires resolving to const only when we are in a const context.
295 impl BoundConstness {
296 /// Reduce `self` and `constness` to two possible combined states instead of four.
297 pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
298 match (constness, self) {
299 (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
301 *this = BoundConstness::NotConst;
302 hir::Constness::NotConst
308 impl fmt::Display for BoundConstness {
309 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
311 Self::NotConst => f.write_str("normal"),
312 Self::ConstIfConst => f.write_str("`~const`"),
317 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
318 #[derive(TypeFoldable, TypeVisitable)]
319 pub struct ClosureSizeProfileData<'tcx> {
320 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
321 pub before_feature_tys: Ty<'tcx>,
322 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
323 pub after_feature_tys: Ty<'tcx>,
326 pub trait DefIdTree: Copy {
327 fn opt_parent(self, id: DefId) -> Option<DefId>;
331 fn parent(self, id: DefId) -> DefId {
332 match self.opt_parent(id) {
334 // not `unwrap_or_else` to avoid breaking caller tracking
335 None => bug!("{id:?} doesn't have a parent"),
341 fn opt_local_parent(self, id: LocalDefId) -> Option<LocalDefId> {
342 self.opt_parent(id.to_def_id()).map(DefId::expect_local)
347 fn local_parent(self, id: LocalDefId) -> LocalDefId {
348 self.parent(id.to_def_id()).expect_local()
351 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
352 if descendant.krate != ancestor.krate {
356 while descendant != ancestor {
357 match self.opt_parent(descendant) {
358 Some(parent) => descendant = parent,
359 None => return false,
366 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
368 fn opt_parent(self, id: DefId) -> Option<DefId> {
369 self.def_key(id).parent.map(|index| DefId { index, ..id })
373 impl<Id> Visibility<Id> {
374 pub fn is_public(self) -> bool {
375 matches!(self, Visibility::Public)
378 pub fn map_id<OutId>(self, f: impl FnOnce(Id) -> OutId) -> Visibility<OutId> {
380 Visibility::Public => Visibility::Public,
381 Visibility::Restricted(id) => Visibility::Restricted(f(id)),
386 impl<Id: Into<DefId>> Visibility<Id> {
387 pub fn to_def_id(self) -> Visibility<DefId> {
388 self.map_id(Into::into)
391 /// Returns `true` if an item with this visibility is accessible from the given module.
392 pub fn is_accessible_from(self, module: impl Into<DefId>, tree: impl DefIdTree) -> bool {
394 // Public items are visible everywhere.
395 Visibility::Public => true,
396 Visibility::Restricted(id) => tree.is_descendant_of(module.into(), id.into()),
400 /// Returns `true` if this visibility is at least as accessible as the given visibility
401 pub fn is_at_least(self, vis: Visibility<impl Into<DefId>>, tree: impl DefIdTree) -> bool {
403 Visibility::Public => self.is_public(),
404 Visibility::Restricted(id) => self.is_accessible_from(id, tree),
409 impl Visibility<DefId> {
410 pub fn expect_local(self) -> Visibility {
411 self.map_id(|id| id.expect_local())
414 // Returns `true` if this item is visible anywhere in the local crate.
415 pub fn is_visible_locally(self) -> bool {
417 Visibility::Public => true,
418 Visibility::Restricted(def_id) => def_id.is_local(),
423 /// The crate variances map is computed during typeck and contains the
424 /// variance of every item in the local crate. You should not use it
425 /// directly, because to do so will make your pass dependent on the
426 /// HIR of every item in the local crate. Instead, use
427 /// `tcx.variances_of()` to get the variance for a *particular*
429 #[derive(HashStable, Debug)]
430 pub struct CrateVariancesMap<'tcx> {
431 /// For each item with generics, maps to a vector of the variance
432 /// of its generics. If an item has no generics, it will have no
434 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
437 // Contains information needed to resolve types and (in the future) look up
438 // the types of AST nodes.
439 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
440 pub struct CReaderCacheKey {
441 pub cnum: Option<CrateNum>,
445 /// Represents a type.
448 /// - This is a very "dumb" struct (with no derives and no `impls`).
449 /// - Values of this type are always interned and thus unique, and are stored
450 /// as an `Interned<TyS>`.
451 /// - `Ty` (which contains a reference to a `Interned<TyS>`) or `Interned<TyS>`
452 /// should be used everywhere instead of `TyS`. In particular, `Ty` has most
453 /// of the relevant methods.
454 #[derive(PartialEq, Eq, PartialOrd, Ord)]
455 #[allow(rustc::usage_of_ty_tykind)]
456 pub(crate) struct TyS<'tcx> {
457 /// This field shouldn't be used directly and may be removed in the future.
458 /// Use `Ty::kind()` instead.
461 /// This field provides fast access to information that is also contained
464 /// This field shouldn't be used directly and may be removed in the future.
465 /// Use `Ty::flags()` instead.
468 /// This field provides fast access to information that is also contained
471 /// This is a kind of confusing thing: it stores the smallest
474 /// (a) the binder itself captures nothing but
475 /// (b) all the late-bound things within the type are captured
476 /// by some sub-binder.
478 /// So, for a type without any late-bound things, like `u32`, this
479 /// will be *innermost*, because that is the innermost binder that
480 /// captures nothing. But for a type `&'D u32`, where `'D` is a
481 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
482 /// -- the binder itself does not capture `D`, but `D` is captured
483 /// by an inner binder.
485 /// We call this concept an "exclusive" binder `D` because all
486 /// De Bruijn indices within the type are contained within `0..D`
488 outer_exclusive_binder: ty::DebruijnIndex,
491 /// Use this rather than `TyS`, whenever possible.
492 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
493 #[rustc_diagnostic_item = "Ty"]
494 #[rustc_pass_by_value]
495 pub struct Ty<'tcx>(Interned<'tcx, WithStableHash<TyS<'tcx>>>);
497 impl<'tcx> TyCtxt<'tcx> {
498 /// A "bool" type used in rustc_mir_transform unit tests when we
499 /// have not spun up a TyCtxt.
500 pub const BOOL_TY_FOR_UNIT_TESTING: Ty<'tcx> = Ty(Interned::new_unchecked(&WithStableHash {
503 flags: TypeFlags::empty(),
504 outer_exclusive_binder: DebruijnIndex::from_usize(0),
506 stable_hash: Fingerprint::ZERO,
510 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
512 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
516 // The other fields just provide fast access to information that is
517 // also contained in `kind`, so no need to hash them.
520 outer_exclusive_binder: _,
523 kind.hash_stable(hcx, hasher)
527 impl ty::EarlyBoundRegion {
528 /// Does this early bound region have a name? Early bound regions normally
529 /// always have names except when using anonymous lifetimes (`'_`).
530 pub fn has_name(&self) -> bool {
531 self.name != kw::UnderscoreLifetime
535 /// Represents a predicate.
537 /// See comments on `TyS`, which apply here too (albeit for
538 /// `PredicateS`/`Predicate` rather than `TyS`/`Ty`).
540 pub(crate) struct PredicateS<'tcx> {
541 kind: Binder<'tcx, PredicateKind<'tcx>>,
543 /// See the comment for the corresponding field of [TyS].
544 outer_exclusive_binder: ty::DebruijnIndex,
547 /// Use this rather than `PredicateS`, whenever possible.
548 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
549 #[rustc_pass_by_value]
550 pub struct Predicate<'tcx>(Interned<'tcx, PredicateS<'tcx>>);
552 impl<'tcx> Predicate<'tcx> {
553 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
555 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
560 pub fn flags(self) -> TypeFlags {
565 pub fn outer_exclusive_binder(self) -> DebruijnIndex {
566 self.0.outer_exclusive_binder
569 /// Flips the polarity of a Predicate.
571 /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
572 pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
575 .map_bound(|kind| match kind {
576 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
577 Some(PredicateKind::Trait(TraitPredicate {
580 polarity: polarity.flip()?,
588 Some(tcx.mk_predicate(kind))
591 pub fn without_const(mut self, tcx: TyCtxt<'tcx>) -> Self {
592 if let PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) = self.kind().skip_binder()
593 && constness != BoundConstness::NotConst
595 self = tcx.mk_predicate(self.kind().rebind(PredicateKind::Trait(TraitPredicate {
597 constness: BoundConstness::NotConst,
604 /// Whether this projection can be soundly normalized.
606 /// Wf predicates must not be normalized, as normalization
607 /// can remove required bounds which would cause us to
608 /// unsoundly accept some programs. See #91068.
610 pub fn allow_normalization(self) -> bool {
611 match self.kind().skip_binder() {
612 PredicateKind::WellFormed(_) => false,
613 PredicateKind::Trait(_)
614 | PredicateKind::RegionOutlives(_)
615 | PredicateKind::TypeOutlives(_)
616 | PredicateKind::Projection(_)
617 | PredicateKind::ObjectSafe(_)
618 | PredicateKind::ClosureKind(_, _, _)
619 | PredicateKind::Subtype(_)
620 | PredicateKind::Coerce(_)
621 | PredicateKind::ConstEvaluatable(_)
622 | PredicateKind::ConstEquate(_, _)
623 | PredicateKind::TypeWellFormedFromEnv(_) => true,
628 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
629 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
633 // The other fields just provide fast access to information that is
634 // also contained in `kind`, so no need to hash them.
636 outer_exclusive_binder: _,
639 kind.hash_stable(hcx, hasher);
643 impl rustc_errors::IntoDiagnosticArg for Predicate<'_> {
644 fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
645 rustc_errors::DiagnosticArgValue::Str(std::borrow::Cow::Owned(self.to_string()))
649 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
650 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
651 pub enum PredicateKind<'tcx> {
652 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
653 /// the `Self` type of the trait reference and `A`, `B`, and `C`
654 /// would be the type parameters.
655 Trait(TraitPredicate<'tcx>),
658 RegionOutlives(RegionOutlivesPredicate<'tcx>),
661 TypeOutlives(TypeOutlivesPredicate<'tcx>),
663 /// `where <T as TraitRef>::Name == X`, approximately.
664 /// See the `ProjectionPredicate` struct for details.
665 Projection(ProjectionPredicate<'tcx>),
667 /// No syntax: `T` well-formed.
668 WellFormed(GenericArg<'tcx>),
670 /// Trait must be object-safe.
673 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
674 /// for some substitutions `...` and `T` being a closure type.
675 /// Satisfied (or refuted) once we know the closure's kind.
676 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
680 /// This obligation is created most often when we have two
681 /// unresolved type variables and hence don't have enough
682 /// information to process the subtyping obligation yet.
683 Subtype(SubtypePredicate<'tcx>),
685 /// `T1` coerced to `T2`
687 /// Like a subtyping obligation, this is created most often
688 /// when we have two unresolved type variables and hence
689 /// don't have enough information to process the coercion
690 /// obligation yet. At the moment, we actually process coercions
691 /// very much like subtyping and don't handle the full coercion
693 Coerce(CoercePredicate<'tcx>),
695 /// Constant initializer must evaluate successfully.
696 ConstEvaluatable(ty::Const<'tcx>),
698 /// Constants must be equal. The first component is the const that is expected.
699 ConstEquate(Const<'tcx>, Const<'tcx>),
701 /// Represents a type found in the environment that we can use for implied bounds.
703 /// Only used for Chalk.
704 TypeWellFormedFromEnv(Ty<'tcx>),
707 /// The crate outlives map is computed during typeck and contains the
708 /// outlives of every item in the local crate. You should not use it
709 /// directly, because to do so will make your pass dependent on the
710 /// HIR of every item in the local crate. Instead, use
711 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
713 #[derive(HashStable, Debug)]
714 pub struct CratePredicatesMap<'tcx> {
715 /// For each struct with outlive bounds, maps to a vector of the
716 /// predicate of its outlive bounds. If an item has no outlives
717 /// bounds, it will have no entry.
718 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
721 impl<'tcx> Predicate<'tcx> {
722 /// Performs a substitution suitable for going from a
723 /// poly-trait-ref to supertraits that must hold if that
724 /// poly-trait-ref holds. This is slightly different from a normal
725 /// substitution in terms of what happens with bound regions. See
726 /// lengthy comment below for details.
727 pub fn subst_supertrait(
730 trait_ref: &ty::PolyTraitRef<'tcx>,
731 ) -> Predicate<'tcx> {
732 // The interaction between HRTB and supertraits is not entirely
733 // obvious. Let me walk you (and myself) through an example.
735 // Let's start with an easy case. Consider two traits:
737 // trait Foo<'a>: Bar<'a,'a> { }
738 // trait Bar<'b,'c> { }
740 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
741 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
742 // knew that `Foo<'x>` (for any 'x) then we also know that
743 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
744 // normal substitution.
746 // In terms of why this is sound, the idea is that whenever there
747 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
748 // holds. So if there is an impl of `T:Foo<'a>` that applies to
749 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
752 // Another example to be careful of is this:
754 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
755 // trait Bar1<'b,'c> { }
757 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
758 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
759 // reason is similar to the previous example: any impl of
760 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
761 // basically we would want to collapse the bound lifetimes from
762 // the input (`trait_ref`) and the supertraits.
764 // To achieve this in practice is fairly straightforward. Let's
765 // consider the more complicated scenario:
767 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
768 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
769 // where both `'x` and `'b` would have a DB index of 1.
770 // The substitution from the input trait-ref is therefore going to be
771 // `'a => 'x` (where `'x` has a DB index of 1).
772 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
773 // early-bound parameter and `'b' is a late-bound parameter with a
775 // - If we replace `'a` with `'x` from the input, it too will have
776 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
777 // just as we wanted.
779 // There is only one catch. If we just apply the substitution `'a
780 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
781 // adjust the DB index because we substituting into a binder (it
782 // tries to be so smart...) resulting in `for<'x> for<'b>
783 // Bar1<'x,'b>` (we have no syntax for this, so use your
784 // imagination). Basically the 'x will have DB index of 2 and 'b
785 // will have DB index of 1. Not quite what we want. So we apply
786 // the substitution to the *contents* of the trait reference,
787 // rather than the trait reference itself (put another way, the
788 // substitution code expects equal binding levels in the values
789 // from the substitution and the value being substituted into, and
790 // this trick achieves that).
792 // Working through the second example:
793 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
794 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
795 // We want to end up with:
796 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
798 // 1) We must shift all bound vars in predicate by the length
799 // of trait ref's bound vars. So, we would end up with predicate like
800 // Self: Bar1<'a, '^0.1>
801 // 2) We can then apply the trait substs to this, ending up with
802 // T: Bar1<'^0.0, '^0.1>
803 // 3) Finally, to create the final bound vars, we concatenate the bound
804 // vars of the trait ref with those of the predicate:
806 let bound_pred = self.kind();
807 let pred_bound_vars = bound_pred.bound_vars();
808 let trait_bound_vars = trait_ref.bound_vars();
809 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
811 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
812 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
813 let new = EarlyBinder(shifted_pred).subst(tcx, trait_ref.skip_binder().substs);
814 // 3) ['x] + ['b] -> ['x, 'b]
816 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
817 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
821 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
822 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
823 pub struct TraitPredicate<'tcx> {
824 pub trait_ref: TraitRef<'tcx>,
826 pub constness: BoundConstness,
828 /// If polarity is Positive: we are proving that the trait is implemented.
830 /// If polarity is Negative: we are proving that a negative impl of this trait
831 /// exists. (Note that coherence also checks whether negative impls of supertraits
832 /// exist via a series of predicates.)
834 /// If polarity is Reserved: that's a bug.
835 pub polarity: ImplPolarity,
838 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
840 impl<'tcx> TraitPredicate<'tcx> {
841 pub fn remap_constness(&mut self, param_env: &mut ParamEnv<'tcx>) {
842 *param_env = param_env.with_constness(self.constness.and(param_env.constness()))
845 /// Remap the constness of this predicate before emitting it for diagnostics.
846 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
847 // this is different to `remap_constness` that callees want to print this predicate
848 // in case of selection errors. `T: ~const Drop` bounds cannot end up here when the
849 // param_env is not const because it is always satisfied in non-const contexts.
850 if let hir::Constness::NotConst = param_env.constness() {
851 self.constness = ty::BoundConstness::NotConst;
855 pub fn with_self_type(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self {
856 Self { trait_ref: self.trait_ref.with_self_type(tcx, self_ty), ..self }
859 pub fn def_id(self) -> DefId {
860 self.trait_ref.def_id
863 pub fn self_ty(self) -> Ty<'tcx> {
864 self.trait_ref.self_ty()
868 pub fn is_const_if_const(self) -> bool {
869 self.constness == BoundConstness::ConstIfConst
872 pub fn is_constness_satisfied_by(self, constness: hir::Constness) -> bool {
873 match (self.constness, constness) {
874 (BoundConstness::NotConst, _)
875 | (BoundConstness::ConstIfConst, hir::Constness::Const) => true,
876 (BoundConstness::ConstIfConst, hir::Constness::NotConst) => false,
880 pub fn without_const(mut self) -> Self {
881 self.constness = BoundConstness::NotConst;
886 impl<'tcx> PolyTraitPredicate<'tcx> {
887 pub fn def_id(self) -> DefId {
888 // Ok to skip binder since trait `DefId` does not care about regions.
889 self.skip_binder().def_id()
892 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
893 self.map_bound(|trait_ref| trait_ref.self_ty())
896 /// Remap the constness of this predicate before emitting it for diagnostics.
897 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
898 *self = self.map_bound(|mut p| {
899 p.remap_constness_diag(param_env);
905 pub fn is_const_if_const(self) -> bool {
906 self.skip_binder().is_const_if_const()
910 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
911 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
912 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
913 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
914 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
915 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
916 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
918 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
919 /// whether the `a` type is the type that we should label as "expected" when
920 /// presenting user diagnostics.
921 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
922 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
923 pub struct SubtypePredicate<'tcx> {
924 pub a_is_expected: bool,
928 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
930 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
931 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
932 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
933 pub struct CoercePredicate<'tcx> {
937 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
939 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
940 pub struct Term<'tcx> {
942 marker: PhantomData<(Ty<'tcx>, Const<'tcx>)>,
945 impl Debug for Term<'_> {
946 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
947 let data = if let Some(ty) = self.ty() {
948 format!("Term::Ty({:?})", ty)
949 } else if let Some(ct) = self.ct() {
950 format!("Term::Ct({:?})", ct)
958 impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
959 fn from(ty: Ty<'tcx>) -> Self {
960 TermKind::Ty(ty).pack()
964 impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
965 fn from(c: Const<'tcx>) -> Self {
966 TermKind::Const(c).pack()
970 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Term<'tcx> {
971 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
972 self.unpack().hash_stable(hcx, hasher);
976 impl<'tcx> TypeFoldable<'tcx> for Term<'tcx> {
977 fn try_fold_with<F: FallibleTypeFolder<'tcx>>(self, folder: &mut F) -> Result<Self, F::Error> {
978 Ok(self.unpack().try_fold_with(folder)?.pack())
982 impl<'tcx> TypeVisitable<'tcx> for Term<'tcx> {
983 fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
984 self.unpack().visit_with(visitor)
988 impl<'tcx, E: TyEncoder<I = TyCtxt<'tcx>>> Encodable<E> for Term<'tcx> {
989 fn encode(&self, e: &mut E) {
990 self.unpack().encode(e)
994 impl<'tcx, D: TyDecoder<I = TyCtxt<'tcx>>> Decodable<D> for Term<'tcx> {
995 fn decode(d: &mut D) -> Self {
996 let res: TermKind<'tcx> = Decodable::decode(d);
1001 impl<'tcx> Term<'tcx> {
1003 pub fn unpack(self) -> TermKind<'tcx> {
1004 let ptr = self.ptr.get();
1005 // SAFETY: use of `Interned::new_unchecked` here is ok because these
1006 // pointers were originally created from `Interned` types in `pack()`,
1007 // and this is just going in the other direction.
1009 match ptr & TAG_MASK {
1010 TYPE_TAG => TermKind::Ty(Ty(Interned::new_unchecked(
1011 &*((ptr & !TAG_MASK) as *const WithStableHash<ty::TyS<'tcx>>),
1013 CONST_TAG => TermKind::Const(ty::Const(Interned::new_unchecked(
1014 &*((ptr & !TAG_MASK) as *const ty::ConstS<'tcx>),
1016 _ => core::intrinsics::unreachable(),
1021 pub fn ty(&self) -> Option<Ty<'tcx>> {
1022 if let TermKind::Ty(ty) = self.unpack() { Some(ty) } else { None }
1025 pub fn ct(&self) -> Option<Const<'tcx>> {
1026 if let TermKind::Const(c) = self.unpack() { Some(c) } else { None }
1029 pub fn into_arg(self) -> GenericArg<'tcx> {
1030 match self.unpack() {
1031 TermKind::Ty(ty) => ty.into(),
1032 TermKind::Const(c) => c.into(),
1037 const TAG_MASK: usize = 0b11;
1038 const TYPE_TAG: usize = 0b00;
1039 const CONST_TAG: usize = 0b01;
1041 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)]
1042 #[derive(HashStable, TypeFoldable, TypeVisitable)]
1043 pub enum TermKind<'tcx> {
1048 impl<'tcx> TermKind<'tcx> {
1050 fn pack(self) -> Term<'tcx> {
1051 let (tag, ptr) = match self {
1052 TermKind::Ty(ty) => {
1053 // Ensure we can use the tag bits.
1054 assert_eq!(mem::align_of_val(&*ty.0.0) & TAG_MASK, 0);
1055 (TYPE_TAG, ty.0.0 as *const WithStableHash<ty::TyS<'tcx>> as usize)
1057 TermKind::Const(ct) => {
1058 // Ensure we can use the tag bits.
1059 assert_eq!(mem::align_of_val(&*ct.0.0) & TAG_MASK, 0);
1060 (CONST_TAG, ct.0.0 as *const ty::ConstS<'tcx> as usize)
1064 Term { ptr: unsafe { NonZeroUsize::new_unchecked(ptr | tag) }, marker: PhantomData }
1068 /// This kind of predicate has no *direct* correspondent in the
1069 /// syntax, but it roughly corresponds to the syntactic forms:
1071 /// 1. `T: TraitRef<..., Item = Type>`
1072 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1074 /// In particular, form #1 is "desugared" to the combination of a
1075 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1076 /// predicates. Form #2 is a broader form in that it also permits
1077 /// equality between arbitrary types. Processing an instance of
1078 /// Form #2 eventually yields one of these `ProjectionPredicate`
1079 /// instances to normalize the LHS.
1080 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1081 #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)]
1082 pub struct ProjectionPredicate<'tcx> {
1083 pub projection_ty: ProjectionTy<'tcx>,
1084 pub term: Term<'tcx>,
1087 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
1089 impl<'tcx> PolyProjectionPredicate<'tcx> {
1090 /// Returns the `DefId` of the trait of the associated item being projected.
1092 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1093 self.skip_binder().projection_ty.trait_def_id(tcx)
1096 /// Get the [PolyTraitRef] required for this projection to be well formed.
1097 /// Note that for generic associated types the predicates of the associated
1098 /// type also need to be checked.
1100 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
1101 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1102 // `self.0.trait_ref` is permitted to have escaping regions.
1103 // This is because here `self` has a `Binder` and so does our
1104 // return value, so we are preserving the number of binding
1106 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1109 pub fn term(&self) -> Binder<'tcx, Term<'tcx>> {
1110 self.map_bound(|predicate| predicate.term)
1113 /// The `DefId` of the `TraitItem` for the associated type.
1115 /// Note that this is not the `DefId` of the `TraitRef` containing this
1116 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1117 pub fn projection_def_id(&self) -> DefId {
1118 // Ok to skip binder since trait `DefId` does not care about regions.
1119 self.skip_binder().projection_ty.item_def_id
1123 pub trait ToPolyTraitRef<'tcx> {
1124 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1127 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1128 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1129 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1133 pub trait ToPredicate<'tcx, Predicate> {
1134 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate;
1137 impl<'tcx, T> ToPredicate<'tcx, T> for T {
1138 fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T {
1143 impl<'tcx> ToPredicate<'tcx, Predicate<'tcx>> for Binder<'tcx, PredicateKind<'tcx>> {
1145 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1146 tcx.mk_predicate(self)
1150 impl<'tcx> ToPredicate<'tcx, Predicate<'tcx>> for PolyTraitPredicate<'tcx> {
1151 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1152 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
1156 impl<'tcx> ToPredicate<'tcx, Predicate<'tcx>> for PolyRegionOutlivesPredicate<'tcx> {
1157 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1158 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
1162 impl<'tcx> ToPredicate<'tcx, Predicate<'tcx>> for PolyTypeOutlivesPredicate<'tcx> {
1163 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1164 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
1168 impl<'tcx> ToPredicate<'tcx, Predicate<'tcx>> for PolyProjectionPredicate<'tcx> {
1169 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1170 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
1174 impl<'tcx> Predicate<'tcx> {
1175 pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
1176 let predicate = self.kind();
1177 match predicate.skip_binder() {
1178 PredicateKind::Trait(t) => Some(predicate.rebind(t)),
1179 PredicateKind::Projection(..)
1180 | PredicateKind::Subtype(..)
1181 | PredicateKind::Coerce(..)
1182 | PredicateKind::RegionOutlives(..)
1183 | PredicateKind::WellFormed(..)
1184 | PredicateKind::ObjectSafe(..)
1185 | PredicateKind::ClosureKind(..)
1186 | PredicateKind::TypeOutlives(..)
1187 | PredicateKind::ConstEvaluatable(..)
1188 | PredicateKind::ConstEquate(..)
1189 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1193 pub fn to_opt_poly_projection_pred(self) -> Option<PolyProjectionPredicate<'tcx>> {
1194 let predicate = self.kind();
1195 match predicate.skip_binder() {
1196 PredicateKind::Projection(t) => Some(predicate.rebind(t)),
1197 PredicateKind::Trait(..)
1198 | PredicateKind::Subtype(..)
1199 | PredicateKind::Coerce(..)
1200 | PredicateKind::RegionOutlives(..)
1201 | PredicateKind::WellFormed(..)
1202 | PredicateKind::ObjectSafe(..)
1203 | PredicateKind::ClosureKind(..)
1204 | PredicateKind::TypeOutlives(..)
1205 | PredicateKind::ConstEvaluatable(..)
1206 | PredicateKind::ConstEquate(..)
1207 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1211 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1212 let predicate = self.kind();
1213 match predicate.skip_binder() {
1214 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
1215 PredicateKind::Trait(..)
1216 | PredicateKind::Projection(..)
1217 | PredicateKind::Subtype(..)
1218 | PredicateKind::Coerce(..)
1219 | PredicateKind::RegionOutlives(..)
1220 | PredicateKind::WellFormed(..)
1221 | PredicateKind::ObjectSafe(..)
1222 | PredicateKind::ClosureKind(..)
1223 | PredicateKind::ConstEvaluatable(..)
1224 | PredicateKind::ConstEquate(..)
1225 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1230 /// Represents the bounds declared on a particular set of type
1231 /// parameters. Should eventually be generalized into a flag list of
1232 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
1233 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1234 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1235 /// the `GenericPredicates` are expressed in terms of the bound type
1236 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1237 /// represented a set of bounds for some particular instantiation,
1238 /// meaning that the generic parameters have been substituted with
1242 /// ```ignore (illustrative)
1243 /// struct Foo<T, U: Bar<T>> { ... }
1245 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1246 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1247 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1248 /// [usize:Bar<isize>]]`.
1249 #[derive(Clone, Debug, TypeFoldable, TypeVisitable)]
1250 pub struct InstantiatedPredicates<'tcx> {
1251 pub predicates: Vec<Predicate<'tcx>>,
1252 pub spans: Vec<Span>,
1255 impl<'tcx> InstantiatedPredicates<'tcx> {
1256 pub fn empty() -> InstantiatedPredicates<'tcx> {
1257 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1260 pub fn is_empty(&self) -> bool {
1261 self.predicates.is_empty()
1265 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable, Lift)]
1266 #[derive(TypeFoldable, TypeVisitable)]
1267 pub struct OpaqueTypeKey<'tcx> {
1268 pub def_id: LocalDefId,
1269 pub substs: SubstsRef<'tcx>,
1272 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, HashStable, TyEncodable, TyDecodable)]
1273 pub struct OpaqueHiddenType<'tcx> {
1274 /// The span of this particular definition of the opaque type. So
1277 /// ```ignore (incomplete snippet)
1278 /// type Foo = impl Baz;
1279 /// fn bar() -> Foo {
1280 /// // ^^^ This is the span we are looking for!
1284 /// In cases where the fn returns `(impl Trait, impl Trait)` or
1285 /// other such combinations, the result is currently
1286 /// over-approximated, but better than nothing.
1289 /// The type variable that represents the value of the opaque type
1290 /// that we require. In other words, after we compile this function,
1291 /// we will be created a constraint like:
1292 /// ```ignore (pseudo-rust)
1295 /// where `?C` is the value of this type variable. =) It may
1296 /// naturally refer to the type and lifetime parameters in scope
1297 /// in this function, though ultimately it should only reference
1298 /// those that are arguments to `Foo` in the constraint above. (In
1299 /// other words, `?C` should not include `'b`, even though it's a
1300 /// lifetime parameter on `foo`.)
1304 impl<'tcx> OpaqueHiddenType<'tcx> {
1305 pub fn report_mismatch(&self, other: &Self, tcx: TyCtxt<'tcx>) {
1306 // Found different concrete types for the opaque type.
1307 let sub_diag = if self.span == other.span {
1308 TypeMismatchReason::ConflictType { span: self.span }
1310 TypeMismatchReason::PreviousUse { span: self.span }
1312 tcx.sess.emit_err(OpaqueHiddenTypeMismatch {
1315 other_span: other.span,
1320 #[instrument(level = "debug", skip(tcx), ret)]
1321 pub fn remap_generic_params_to_declaration_params(
1323 opaque_type_key: OpaqueTypeKey<'tcx>,
1325 // typeck errors have subpar spans for opaque types, so delay error reporting until borrowck.
1326 ignore_errors: bool,
1327 origin: OpaqueTyOrigin,
1329 let OpaqueTypeKey { def_id, substs } = opaque_type_key;
1331 // Use substs to build up a reverse map from regions to their
1332 // identity mappings. This is necessary because of `impl
1333 // Trait` lifetimes are computed by replacing existing
1334 // lifetimes with 'static and remapping only those used in the
1335 // `impl Trait` return type, resulting in the parameters
1337 let id_substs = InternalSubsts::identity_for_item(tcx, def_id.to_def_id());
1340 // This zip may have several times the same lifetime in `substs` paired with a different
1341 // lifetime from `id_substs`. Simply `collect`ing the iterator is the correct behaviour:
1342 // it will pick the last one, which is the one we introduced in the impl-trait desugaring.
1343 let map = substs.iter().zip(id_substs);
1345 let map: FxHashMap<GenericArg<'tcx>, GenericArg<'tcx>> = match origin {
1346 // HACK: The HIR lowering for async fn does not generate
1347 // any `+ Captures<'x>` bounds for the `impl Future<...>`, so all async fns with lifetimes
1348 // would now fail to compile. We should probably just make hir lowering fill this in properly.
1349 OpaqueTyOrigin::AsyncFn(_) => map.collect(),
1350 OpaqueTyOrigin::FnReturn(_) | OpaqueTyOrigin::TyAlias => {
1351 // Opaque types may only use regions that are bound. So for
1353 // type Foo<'a, 'b, 'c> = impl Trait<'a> + 'b;
1355 // we may not use `'c` in the hidden type.
1356 let variances = tcx.variances_of(def_id);
1359 map.filter(|(_, v)| {
1360 let ty::GenericArgKind::Lifetime(lt) = v.unpack() else { return true };
1361 let ty::ReEarlyBound(ebr) = lt.kind() else { bug!() };
1362 variances[ebr.index as usize] == ty::Variance::Invariant
1367 debug!("map = {:#?}", map);
1369 // Convert the type from the function into a type valid outside
1370 // the function, by replacing invalid regions with 'static,
1371 // after producing an error for each of them.
1372 self.fold_with(&mut opaque_types::ReverseMapper::new(tcx, map, self.span, ignore_errors))
1376 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1377 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1378 /// regions/types/consts within the same universe simply have an unknown relationship to one
1380 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
1381 #[derive(HashStable, TyEncodable, TyDecodable)]
1382 pub struct Placeholder<T> {
1383 pub universe: UniverseIndex,
1387 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1389 pub type PlaceholderType = Placeholder<BoundVar>;
1391 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1392 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1393 pub struct BoundConst<'tcx> {
1398 pub type PlaceholderConst<'tcx> = Placeholder<BoundVar>;
1400 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1401 /// the `DefId` of the generic parameter it instantiates.
1403 /// This is used to avoid calls to `type_of` for const arguments during typeck
1404 /// which cause cycle errors.
1409 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1410 /// // ^ const parameter
1414 /// fn foo<const M: u8>(&self) -> usize { 42 }
1415 /// // ^ const parameter
1420 /// let _b = a.foo::<{ 3 + 7 }>();
1421 /// // ^^^^^^^^^ const argument
1425 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1426 /// which `foo` is used until we know the type of `a`.
1428 /// We only know the type of `a` once we are inside of `typeck(main)`.
1429 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1430 /// requires us to evaluate the const argument.
1432 /// To evaluate that const argument we need to know its type,
1433 /// which we would get using `type_of(const_arg)`. This requires us to
1434 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1435 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1436 /// which results in a cycle.
1438 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1440 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1441 /// already resolved `foo` so we know which const parameter this argument instantiates.
1442 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1443 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1444 /// trivial to compute.
1446 /// If we now want to use that constant in a place which potentially needs its type
1447 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1448 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1449 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1450 /// to get the type of `did`.
1451 #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, Lift, TyEncodable, TyDecodable)]
1452 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1453 #[derive(Hash, HashStable)]
1454 pub struct WithOptConstParam<T> {
1456 /// The `DefId` of the corresponding generic parameter in case `did` is
1457 /// a const argument.
1459 /// Note that even if `did` is a const argument, this may still be `None`.
1460 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1461 /// to potentially update `param_did` in the case it is `None`.
1462 pub const_param_did: Option<DefId>,
1465 impl<T> WithOptConstParam<T> {
1466 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1468 pub fn unknown(did: T) -> WithOptConstParam<T> {
1469 WithOptConstParam { did, const_param_did: None }
1473 impl WithOptConstParam<LocalDefId> {
1474 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1475 /// `None` otherwise.
1477 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1478 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1481 /// In case `self` is unknown but `self.did` is a const argument, this returns
1482 /// a `WithOptConstParam` with the correct `const_param_did`.
1484 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1485 if self.const_param_did.is_none() {
1486 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1487 return Some(WithOptConstParam { did: self.did, const_param_did });
1494 pub fn to_global(self) -> WithOptConstParam<DefId> {
1495 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1498 pub fn def_id_for_type_of(self) -> DefId {
1499 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1503 impl WithOptConstParam<DefId> {
1504 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1507 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1510 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1511 if let Some(param_did) = self.const_param_did {
1512 if let Some(did) = self.did.as_local() {
1513 return Some((did, param_did));
1520 pub fn is_local(self) -> bool {
1524 pub fn def_id_for_type_of(self) -> DefId {
1525 self.const_param_did.unwrap_or(self.did)
1529 /// When type checking, we use the `ParamEnv` to track
1530 /// details about the set of where-clauses that are in scope at this
1531 /// particular point.
1532 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1533 pub struct ParamEnv<'tcx> {
1534 /// This packs both caller bounds and the reveal enum into one pointer.
1536 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1537 /// basically the set of bounds on the in-scope type parameters, translated
1538 /// into `Obligation`s, and elaborated and normalized.
1540 /// Use the `caller_bounds()` method to access.
1542 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1543 /// want `Reveal::All`.
1545 /// Note: This is packed, use the reveal() method to access it.
1546 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
1549 #[derive(Copy, Clone)]
1551 reveal: traits::Reveal,
1552 constness: hir::Constness,
1555 unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
1556 const BITS: usize = 2;
1558 fn into_usize(self) -> usize {
1560 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
1561 Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
1562 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
1563 Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
1567 unsafe fn from_usize(ptr: usize) -> Self {
1569 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1570 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
1571 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
1572 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
1573 _ => std::hint::unreachable_unchecked(),
1578 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1579 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1580 f.debug_struct("ParamEnv")
1581 .field("caller_bounds", &self.caller_bounds())
1582 .field("reveal", &self.reveal())
1583 .field("constness", &self.constness())
1588 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1589 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1590 self.caller_bounds().hash_stable(hcx, hasher);
1591 self.reveal().hash_stable(hcx, hasher);
1592 self.constness().hash_stable(hcx, hasher);
1596 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1597 fn try_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
1600 ) -> Result<Self, F::Error> {
1602 self.caller_bounds().try_fold_with(folder)?,
1603 self.reveal().try_fold_with(folder)?,
1609 impl<'tcx> TypeVisitable<'tcx> for ParamEnv<'tcx> {
1610 fn visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1611 self.caller_bounds().visit_with(visitor)?;
1612 self.reveal().visit_with(visitor)
1616 impl<'tcx> ParamEnv<'tcx> {
1617 /// Construct a trait environment suitable for contexts where
1618 /// there are no where-clauses in scope. Hidden types (like `impl
1619 /// Trait`) are left hidden, so this is suitable for ordinary
1622 pub fn empty() -> Self {
1623 Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
1627 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1628 self.packed.pointer()
1632 pub fn reveal(self) -> traits::Reveal {
1633 self.packed.tag().reveal
1637 pub fn constness(self) -> hir::Constness {
1638 self.packed.tag().constness
1642 pub fn is_const(self) -> bool {
1643 self.packed.tag().constness == hir::Constness::Const
1646 /// Construct a trait environment with no where-clauses in scope
1647 /// where the values of all `impl Trait` and other hidden types
1648 /// are revealed. This is suitable for monomorphized, post-typeck
1649 /// environments like codegen or doing optimizations.
1651 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1652 /// or invoke `param_env.with_reveal_all()`.
1654 pub fn reveal_all() -> Self {
1655 Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
1658 /// Construct a trait environment with the given set of predicates.
1661 caller_bounds: &'tcx List<Predicate<'tcx>>,
1663 constness: hir::Constness,
1665 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
1668 pub fn with_user_facing(mut self) -> Self {
1669 self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
1674 pub fn with_constness(mut self, constness: hir::Constness) -> Self {
1675 self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
1680 pub fn with_const(mut self) -> Self {
1681 self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
1686 pub fn without_const(mut self) -> Self {
1687 self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
1692 pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
1693 *self = self.with_constness(constness.and(self.constness()))
1696 /// Returns a new parameter environment with the same clauses, but
1697 /// which "reveals" the true results of projections in all cases
1698 /// (even for associated types that are specializable). This is
1699 /// the desired behavior during codegen and certain other special
1700 /// contexts; normally though we want to use `Reveal::UserFacing`,
1701 /// which is the default.
1702 /// All opaque types in the caller_bounds of the `ParamEnv`
1703 /// will be normalized to their underlying types.
1704 /// See PR #65989 and issue #65918 for more details
1705 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1706 if self.packed.tag().reveal == traits::Reveal::All {
1711 tcx.normalize_opaque_types(self.caller_bounds()),
1717 /// Returns this same environment but with no caller bounds.
1719 pub fn without_caller_bounds(self) -> Self {
1720 Self::new(List::empty(), self.reveal(), self.constness())
1723 /// Creates a suitable environment in which to perform trait
1724 /// queries on the given value. When type-checking, this is simply
1725 /// the pair of the environment plus value. But when reveal is set to
1726 /// All, then if `value` does not reference any type parameters, we will
1727 /// pair it with the empty environment. This improves caching and is generally
1730 /// N.B., we preserve the environment when type-checking because it
1731 /// is possible for the user to have wacky where-clauses like
1732 /// `where Box<u32>: Copy`, which are clearly never
1733 /// satisfiable. We generally want to behave as if they were true,
1734 /// although the surrounding function is never reachable.
1735 pub fn and<T: TypeVisitable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1736 match self.reveal() {
1737 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1740 if value.is_global() {
1741 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1743 ParamEnvAnd { param_env: self, value }
1750 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1751 // the constness of trait bounds is being propagated correctly.
1752 impl<'tcx> PolyTraitRef<'tcx> {
1754 pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
1755 self.map_bound(|trait_ref| ty::TraitPredicate {
1758 polarity: ty::ImplPolarity::Positive,
1763 pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
1764 self.with_constness(BoundConstness::NotConst)
1768 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable, TypeVisitable)]
1769 #[derive(HashStable, Lift)]
1770 pub struct ParamEnvAnd<'tcx, T> {
1771 pub param_env: ParamEnv<'tcx>,
1775 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1776 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1777 (self.param_env, self.value)
1781 pub fn without_const(mut self) -> Self {
1782 self.param_env = self.param_env.without_const();
1787 #[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
1788 pub struct Destructor {
1789 /// The `DefId` of the destructor method
1791 /// The constness of the destructor method
1792 pub constness: hir::Constness,
1796 #[derive(HashStable, TyEncodable, TyDecodable)]
1797 pub struct VariantFlags: u32 {
1798 const NO_VARIANT_FLAGS = 0;
1799 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1800 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1801 /// Indicates whether this variant was obtained as part of recovering from
1802 /// a syntactic error. May be incomplete or bogus.
1803 const IS_RECOVERED = 1 << 1;
1807 /// Definition of a variant -- a struct's fields or an enum variant.
1808 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1809 pub struct VariantDef {
1810 /// `DefId` that identifies the variant itself.
1811 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1813 /// `DefId` that identifies the variant's constructor.
1814 /// If this variant is a struct variant, then this is `None`.
1815 pub ctor: Option<(CtorKind, DefId)>,
1816 /// Variant or struct name.
1818 /// Discriminant of this variant.
1819 pub discr: VariantDiscr,
1820 /// Fields of this variant.
1821 pub fields: Vec<FieldDef>,
1822 /// Flags of the variant (e.g. is field list non-exhaustive)?
1823 flags: VariantFlags,
1827 /// Creates a new `VariantDef`.
1829 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1830 /// represents an enum variant).
1832 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1833 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1835 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1836 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1837 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1838 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1839 /// built-in trait), and we do not want to load attributes twice.
1841 /// If someone speeds up attribute loading to not be a performance concern, they can
1842 /// remove this hack and use the constructor `DefId` everywhere.
1845 variant_did: Option<DefId>,
1846 ctor: Option<(CtorKind, DefId)>,
1847 discr: VariantDiscr,
1848 fields: Vec<FieldDef>,
1852 is_field_list_non_exhaustive: bool,
1855 "VariantDef::new(name = {:?}, variant_did = {:?}, ctor = {:?}, discr = {:?},
1856 fields = {:?}, adt_kind = {:?}, parent_did = {:?})",
1857 name, variant_did, ctor, discr, fields, adt_kind, parent_did,
1860 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1861 if is_field_list_non_exhaustive {
1862 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1866 flags |= VariantFlags::IS_RECOVERED;
1869 VariantDef { def_id: variant_did.unwrap_or(parent_did), ctor, name, discr, fields, flags }
1872 /// Is this field list non-exhaustive?
1874 pub fn is_field_list_non_exhaustive(&self) -> bool {
1875 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1878 /// Was this variant obtained as part of recovering from a syntactic error?
1880 pub fn is_recovered(&self) -> bool {
1881 self.flags.intersects(VariantFlags::IS_RECOVERED)
1884 /// Computes the `Ident` of this variant by looking up the `Span`
1885 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1886 Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1890 pub fn ctor_kind(&self) -> Option<CtorKind> {
1891 self.ctor.map(|(kind, _)| kind)
1895 pub fn ctor_def_id(&self) -> Option<DefId> {
1896 self.ctor.map(|(_, def_id)| def_id)
1900 impl PartialEq for VariantDef {
1902 fn eq(&self, other: &Self) -> bool {
1903 // There should be only one `VariantDef` for each `def_id`, therefore
1904 // it is fine to implement `PartialEq` only based on `def_id`.
1906 // Below, we exhaustively destructure `self` and `other` so that if the
1907 // definition of `VariantDef` changes, a compile-error will be produced,
1908 // reminding us to revisit this assumption.
1910 let Self { def_id: lhs_def_id, ctor: _, name: _, discr: _, fields: _, flags: _ } = &self;
1911 let Self { def_id: rhs_def_id, ctor: _, name: _, discr: _, fields: _, flags: _ } = other;
1912 lhs_def_id == rhs_def_id
1916 impl Eq for VariantDef {}
1918 impl Hash for VariantDef {
1920 fn hash<H: Hasher>(&self, s: &mut H) {
1921 // There should be only one `VariantDef` for each `def_id`, therefore
1922 // it is fine to implement `Hash` only based on `def_id`.
1924 // Below, we exhaustively destructure `self` so that if the definition
1925 // of `VariantDef` changes, a compile-error will be produced, reminding
1926 // us to revisit this assumption.
1928 let Self { def_id, ctor: _, name: _, discr: _, fields: _, flags: _ } = &self;
1933 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1934 pub enum VariantDiscr {
1935 /// Explicit value for this variant, i.e., `X = 123`.
1936 /// The `DefId` corresponds to the embedded constant.
1939 /// The previous variant's discriminant plus one.
1940 /// For efficiency reasons, the distance from the
1941 /// last `Explicit` discriminant is being stored,
1942 /// or `0` for the first variant, if it has none.
1946 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1947 pub struct FieldDef {
1950 pub vis: Visibility<DefId>,
1953 impl PartialEq for FieldDef {
1955 fn eq(&self, other: &Self) -> bool {
1956 // There should be only one `FieldDef` for each `did`, therefore it is
1957 // fine to implement `PartialEq` only based on `did`.
1959 // Below, we exhaustively destructure `self` so that if the definition
1960 // of `FieldDef` changes, a compile-error will be produced, reminding
1961 // us to revisit this assumption.
1963 let Self { did: lhs_did, name: _, vis: _ } = &self;
1965 let Self { did: rhs_did, name: _, vis: _ } = other;
1971 impl Eq for FieldDef {}
1973 impl Hash for FieldDef {
1975 fn hash<H: Hasher>(&self, s: &mut H) {
1976 // There should be only one `FieldDef` for each `did`, therefore it is
1977 // fine to implement `Hash` only based on `did`.
1979 // Below, we exhaustively destructure `self` so that if the definition
1980 // of `FieldDef` changes, a compile-error will be produced, reminding
1981 // us to revisit this assumption.
1983 let Self { did, name: _, vis: _ } = &self;
1990 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1991 pub struct ReprFlags: u8 {
1992 const IS_C = 1 << 0;
1993 const IS_SIMD = 1 << 1;
1994 const IS_TRANSPARENT = 1 << 2;
1995 // Internal only for now. If true, don't reorder fields.
1996 const IS_LINEAR = 1 << 3;
1997 // If true, the type's layout can be randomized using
1998 // the seed stored in `ReprOptions.layout_seed`
1999 const RANDOMIZE_LAYOUT = 1 << 4;
2000 // Any of these flags being set prevent field reordering optimisation.
2001 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
2002 | ReprFlags::IS_SIMD.bits
2003 | ReprFlags::IS_LINEAR.bits;
2007 /// Represents the repr options provided by the user,
2008 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
2009 pub struct ReprOptions {
2010 pub int: Option<attr::IntType>,
2011 pub align: Option<Align>,
2012 pub pack: Option<Align>,
2013 pub flags: ReprFlags,
2014 /// The seed to be used for randomizing a type's layout
2016 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
2017 /// be the "most accurate" hash as it'd encompass the item and crate
2018 /// hash without loss, but it does pay the price of being larger.
2019 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
2020 /// purposes (primarily `-Z randomize-layout`)
2021 pub field_shuffle_seed: u64,
2025 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
2026 let mut flags = ReprFlags::empty();
2027 let mut size = None;
2028 let mut max_align: Option<Align> = None;
2029 let mut min_pack: Option<Align> = None;
2031 // Generate a deterministically-derived seed from the item's path hash
2032 // to allow for cross-crate compilation to actually work
2033 let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
2035 // If the user defined a custom seed for layout randomization, xor the item's
2036 // path hash with the user defined seed, this will allowing determinism while
2037 // still allowing users to further randomize layout generation for e.g. fuzzing
2038 if let Some(user_seed) = tcx.sess.opts.unstable_opts.layout_seed {
2039 field_shuffle_seed ^= user_seed;
2042 for attr in tcx.get_attrs(did, sym::repr) {
2043 for r in attr::parse_repr_attr(&tcx.sess, attr) {
2044 flags.insert(match r {
2045 attr::ReprC => ReprFlags::IS_C,
2046 attr::ReprPacked(pack) => {
2047 let pack = Align::from_bytes(pack as u64).unwrap();
2048 min_pack = Some(if let Some(min_pack) = min_pack {
2055 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2056 attr::ReprSimd => ReprFlags::IS_SIMD,
2057 attr::ReprInt(i) => {
2061 attr::ReprAlign(align) => {
2062 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2069 // If `-Z randomize-layout` was enabled for the type definition then we can
2070 // consider performing layout randomization
2071 if tcx.sess.opts.unstable_opts.randomize_layout {
2072 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
2075 // This is here instead of layout because the choice must make it into metadata.
2076 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2077 flags.insert(ReprFlags::IS_LINEAR);
2080 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
2084 pub fn simd(&self) -> bool {
2085 self.flags.contains(ReprFlags::IS_SIMD)
2089 pub fn c(&self) -> bool {
2090 self.flags.contains(ReprFlags::IS_C)
2094 pub fn packed(&self) -> bool {
2099 pub fn transparent(&self) -> bool {
2100 self.flags.contains(ReprFlags::IS_TRANSPARENT)
2104 pub fn linear(&self) -> bool {
2105 self.flags.contains(ReprFlags::IS_LINEAR)
2108 /// Returns the discriminant type, given these `repr` options.
2109 /// This must only be called on enums!
2110 pub fn discr_type(&self) -> attr::IntType {
2111 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2114 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2115 /// layout" optimizations, such as representing `Foo<&T>` as a
2117 pub fn inhibit_enum_layout_opt(&self) -> bool {
2118 self.c() || self.int.is_some()
2121 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2122 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2123 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2124 if let Some(pack) = self.pack {
2125 if pack.bytes() == 1 {
2130 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2133 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
2134 /// was enabled for its declaration crate
2135 pub fn can_randomize_type_layout(&self) -> bool {
2136 !self.inhibit_struct_field_reordering_opt()
2137 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
2140 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2141 pub fn inhibit_union_abi_opt(&self) -> bool {
2146 impl<'tcx> FieldDef {
2147 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
2148 /// typically obtained via the second field of [`TyKind::Adt`].
2149 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2150 tcx.bound_type_of(self.did).subst(tcx, subst)
2153 /// Computes the `Ident` of this variant by looking up the `Span`
2154 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
2155 Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
2159 pub type Attributes<'tcx> = impl Iterator<Item = &'tcx ast::Attribute>;
2160 #[derive(Debug, PartialEq, Eq)]
2161 pub enum ImplOverlapKind {
2162 /// These impls are always allowed to overlap.
2164 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
2167 /// These impls are allowed to overlap, but that raises
2168 /// an issue #33140 future-compatibility warning.
2170 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2171 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2173 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2174 /// that difference, making what reduces to the following set of impls:
2176 /// ```compile_fail,(E0119)
2178 /// impl Trait for dyn Send + Sync {}
2179 /// impl Trait for dyn Sync + Send {}
2182 /// Obviously, once we made these types be identical, that code causes a coherence
2183 /// error and a fairly big headache for us. However, luckily for us, the trait
2184 /// `Trait` used in this case is basically a marker trait, and therefore having
2185 /// overlapping impls for it is sound.
2187 /// To handle this, we basically regard the trait as a marker trait, with an additional
2188 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2189 /// it has the following restrictions:
2191 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2193 /// 2. The trait-ref of both impls must be equal.
2194 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2196 /// 4. Neither of the impls can have any where-clauses.
2198 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2202 impl<'tcx> TyCtxt<'tcx> {
2203 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
2204 self.typeck(self.hir().body_owner_def_id(body))
2207 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
2208 self.associated_items(id)
2209 .in_definition_order()
2210 .filter(move |item| item.kind == AssocKind::Fn && item.defaultness(self).has_value())
2213 /// Look up the name of a definition across crates. This does not look at HIR.
2214 pub fn opt_item_name(self, def_id: DefId) -> Option<Symbol> {
2215 if let Some(cnum) = def_id.as_crate_root() {
2216 Some(self.crate_name(cnum))
2218 let def_key = self.def_key(def_id);
2219 match def_key.disambiguated_data.data {
2220 // The name of a constructor is that of its parent.
2221 rustc_hir::definitions::DefPathData::Ctor => self
2222 .opt_item_name(DefId { krate: def_id.krate, index: def_key.parent.unwrap() }),
2223 // The name of opaque types only exists in HIR.
2224 rustc_hir::definitions::DefPathData::ImplTrait
2225 if let Some(def_id) = def_id.as_local() =>
2226 self.hir().opt_name(self.hir().local_def_id_to_hir_id(def_id)),
2227 _ => def_key.get_opt_name(),
2232 /// Look up the name of a definition across crates. This does not look at HIR.
2234 /// This method will ICE if the corresponding item does not have a name. In these cases, use
2235 /// [`opt_item_name`] instead.
2237 /// [`opt_item_name`]: Self::opt_item_name
2238 pub fn item_name(self, id: DefId) -> Symbol {
2239 self.opt_item_name(id).unwrap_or_else(|| {
2240 bug!("item_name: no name for {:?}", self.def_path(id));
2244 /// Look up the name and span of a definition.
2246 /// See [`item_name`][Self::item_name] for more information.
2247 pub fn opt_item_ident(self, def_id: DefId) -> Option<Ident> {
2248 let def = self.opt_item_name(def_id)?;
2251 .and_then(|id| self.def_ident_span(id))
2252 .unwrap_or(rustc_span::DUMMY_SP);
2253 Some(Ident::new(def, span))
2256 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2257 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2258 Some(self.associated_item(def_id))
2264 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
2265 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
2268 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2272 .position(|field| self.hygienic_eq(ident, field.ident(self), variant.def_id))
2275 /// Returns `true` if the impls are the same polarity and the trait either
2276 /// has no items or is annotated `#[marker]` and prevents item overrides.
2277 pub fn impls_are_allowed_to_overlap(
2281 ) -> Option<ImplOverlapKind> {
2282 // If either trait impl references an error, they're allowed to overlap,
2283 // as one of them essentially doesn't exist.
2284 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2285 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2287 return Some(ImplOverlapKind::Permitted { marker: false });
2290 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2291 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2292 // `#[rustc_reservation_impl]` impls don't overlap with anything
2294 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2297 return Some(ImplOverlapKind::Permitted { marker: false });
2299 (ImplPolarity::Positive, ImplPolarity::Negative)
2300 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2301 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2303 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2308 (ImplPolarity::Positive, ImplPolarity::Positive)
2309 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2312 let is_marker_overlap = {
2313 let is_marker_impl = |def_id: DefId| -> bool {
2314 let trait_ref = self.impl_trait_ref(def_id);
2315 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2317 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2320 if is_marker_overlap {
2322 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2325 Some(ImplOverlapKind::Permitted { marker: true })
2327 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2328 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2329 if self_ty1 == self_ty2 {
2331 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2334 return Some(ImplOverlapKind::Issue33140);
2337 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2338 def_id1, def_id2, self_ty1, self_ty2
2344 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2349 /// Returns `ty::VariantDef` if `res` refers to a struct,
2350 /// or variant or their constructors, panics otherwise.
2351 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2353 Res::Def(DefKind::Variant, did) => {
2354 let enum_did = self.parent(did);
2355 self.adt_def(enum_did).variant_with_id(did)
2357 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2358 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2359 let variant_did = self.parent(variant_ctor_did);
2360 let enum_did = self.parent(variant_did);
2361 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2363 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2364 let struct_did = self.parent(ctor_did);
2365 self.adt_def(struct_did).non_enum_variant()
2367 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2371 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2372 #[instrument(skip(self), level = "debug")]
2373 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2375 ty::InstanceDef::Item(def) => {
2376 debug!("calling def_kind on def: {:?}", def);
2377 let def_kind = self.def_kind(def.did);
2378 debug!("returned from def_kind: {:?}", def_kind);
2381 | DefKind::Static(..)
2382 | DefKind::AssocConst
2384 | DefKind::AnonConst
2385 | DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
2386 // If the caller wants `mir_for_ctfe` of a function they should not be using
2387 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2389 assert_eq!(def.const_param_did, None);
2390 self.optimized_mir(def.did)
2394 ty::InstanceDef::VTableShim(..)
2395 | ty::InstanceDef::ReifyShim(..)
2396 | ty::InstanceDef::Intrinsic(..)
2397 | ty::InstanceDef::FnPtrShim(..)
2398 | ty::InstanceDef::Virtual(..)
2399 | ty::InstanceDef::ClosureOnceShim { .. }
2400 | ty::InstanceDef::DropGlue(..)
2401 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2405 // FIXME(@lcnr): Remove this function.
2406 pub fn get_attrs_unchecked(self, did: DefId) -> &'tcx [ast::Attribute] {
2407 if let Some(did) = did.as_local() {
2408 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2410 self.item_attrs(did)
2414 /// Gets all attributes with the given name.
2415 pub fn get_attrs(self, did: DefId, attr: Symbol) -> ty::Attributes<'tcx> {
2416 let filter_fn = move |a: &&ast::Attribute| a.has_name(attr);
2417 if let Some(did) = did.as_local() {
2418 self.hir().attrs(self.hir().local_def_id_to_hir_id(did)).iter().filter(filter_fn)
2419 } else if cfg!(debug_assertions) && rustc_feature::is_builtin_only_local(attr) {
2420 bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr);
2422 self.item_attrs(did).iter().filter(filter_fn)
2426 pub fn get_attr(self, did: DefId, attr: Symbol) -> Option<&'tcx ast::Attribute> {
2427 if cfg!(debug_assertions) && !rustc_feature::is_valid_for_get_attr(attr) {
2428 bug!("get_attr: unexpected called with DefId `{:?}`, attr `{:?}`", did, attr);
2430 self.get_attrs(did, attr).next()
2434 /// Determines whether an item is annotated with an attribute.
2435 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2436 if cfg!(debug_assertions) && !did.is_local() && rustc_feature::is_builtin_only_local(attr) {
2437 bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr);
2439 self.get_attrs(did, attr).next().is_some()
2443 /// Returns `true` if this is an `auto trait`.
2444 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2445 self.trait_def(trait_def_id).has_auto_impl
2448 pub fn trait_is_coinductive(self, trait_def_id: DefId) -> bool {
2449 self.trait_is_auto(trait_def_id) || self.lang_items().sized_trait() == Some(trait_def_id)
2452 /// Returns layout of a generator. Layout might be unavailable if the
2453 /// generator is tainted by errors.
2454 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2455 self.optimized_mir(def_id).generator_layout()
2458 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2459 /// If it implements no trait, returns `None`.
2460 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2461 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2464 /// If the given `DefId` describes an item belonging to a trait,
2465 /// returns the `DefId` of the trait that the trait item belongs to;
2466 /// otherwise, returns `None`.
2467 pub fn trait_of_item(self, def_id: DefId) -> Option<DefId> {
2468 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2469 let parent = self.parent(def_id);
2470 if let DefKind::Trait | DefKind::TraitAlias = self.def_kind(parent) {
2471 return Some(parent);
2477 /// If the given `DefId` describes a method belonging to an impl, returns the
2478 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2479 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2480 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2481 let parent = self.parent(def_id);
2482 if let DefKind::Impl = self.def_kind(parent) {
2483 return Some(parent);
2489 /// If the given `DefId` belongs to a trait that was automatically derived, returns `true`.
2490 pub fn is_builtin_derive(self, def_id: DefId) -> bool {
2491 self.has_attr(def_id, sym::automatically_derived)
2494 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2495 /// with the name of the crate containing the impl.
2496 pub fn span_of_impl(self, impl_def_id: DefId) -> Result<Span, Symbol> {
2497 if let Some(impl_def_id) = impl_def_id.as_local() {
2498 Ok(self.def_span(impl_def_id))
2500 Err(self.crate_name(impl_def_id.krate))
2504 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2505 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2506 /// definition's parent/scope to perform comparison.
2507 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2508 // We could use `Ident::eq` here, but we deliberately don't. The name
2509 // comparison fails frequently, and we want to avoid the expensive
2510 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2511 use_name.name == def_name.name
2515 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2518 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2519 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2523 pub fn adjust_ident_and_get_scope(
2528 ) -> (Ident, DefId) {
2531 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2532 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2533 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2537 /// Returns `true` if the debuginfo for `span` should be collapsed to the outermost expansion
2538 /// site. Only applies when `Span` is the result of macro expansion.
2540 /// - If the `collapse_debuginfo` feature is enabled then debuginfo is not collapsed by default
2541 /// and only when a macro definition is annotated with `#[collapse_debuginfo]`.
2542 /// - If `collapse_debuginfo` is not enabled, then debuginfo is collapsed by default.
2544 /// When `-Zdebug-macros` is provided then debuginfo will never be collapsed.
2545 pub fn should_collapse_debuginfo(self, span: Span) -> bool {
2546 !self.sess.opts.unstable_opts.debug_macros
2547 && if self.features().collapse_debuginfo {
2548 span.in_macro_expansion_with_collapse_debuginfo()
2550 // Inlined spans should not be collapsed as that leads to all of the
2551 // inlined code being attributed to the inline callsite.
2552 span.from_expansion() && !span.is_inlined()
2556 pub fn is_object_safe(self, key: DefId) -> bool {
2557 self.object_safety_violations(key).is_empty()
2561 pub fn is_const_fn_raw(self, def_id: DefId) -> bool {
2562 matches!(self.def_kind(def_id), DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..))
2563 && self.constness(def_id) == hir::Constness::Const
2567 pub fn is_const_default_method(self, def_id: DefId) -> bool {
2568 matches!(self.trait_of_item(def_id), Some(trait_id) if self.has_attr(trait_id, sym::const_trait))
2571 pub fn impl_trait_in_trait_parent(self, mut def_id: DefId) -> DefId {
2572 while let def_kind = self.def_kind(def_id) && def_kind != DefKind::AssocFn {
2573 debug_assert_eq!(def_kind, DefKind::ImplTraitPlaceholder);
2574 def_id = self.parent(def_id);
2580 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
2581 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
2582 let def_id = def_id.as_local()?;
2583 if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) {
2584 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2585 return match opaque_ty.origin {
2586 hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
2589 hir::OpaqueTyOrigin::TyAlias => None,
2596 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2598 ast::IntTy::Isize => IntTy::Isize,
2599 ast::IntTy::I8 => IntTy::I8,
2600 ast::IntTy::I16 => IntTy::I16,
2601 ast::IntTy::I32 => IntTy::I32,
2602 ast::IntTy::I64 => IntTy::I64,
2603 ast::IntTy::I128 => IntTy::I128,
2607 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2609 ast::UintTy::Usize => UintTy::Usize,
2610 ast::UintTy::U8 => UintTy::U8,
2611 ast::UintTy::U16 => UintTy::U16,
2612 ast::UintTy::U32 => UintTy::U32,
2613 ast::UintTy::U64 => UintTy::U64,
2614 ast::UintTy::U128 => UintTy::U128,
2618 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2620 ast::FloatTy::F32 => FloatTy::F32,
2621 ast::FloatTy::F64 => FloatTy::F64,
2625 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2627 IntTy::Isize => ast::IntTy::Isize,
2628 IntTy::I8 => ast::IntTy::I8,
2629 IntTy::I16 => ast::IntTy::I16,
2630 IntTy::I32 => ast::IntTy::I32,
2631 IntTy::I64 => ast::IntTy::I64,
2632 IntTy::I128 => ast::IntTy::I128,
2636 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2638 UintTy::Usize => ast::UintTy::Usize,
2639 UintTy::U8 => ast::UintTy::U8,
2640 UintTy::U16 => ast::UintTy::U16,
2641 UintTy::U32 => ast::UintTy::U32,
2642 UintTy::U64 => ast::UintTy::U64,
2643 UintTy::U128 => ast::UintTy::U128,
2647 pub fn provide(providers: &mut ty::query::Providers) {
2648 closure::provide(providers);
2649 context::provide(providers);
2650 erase_regions::provide(providers);
2651 inhabitedness::provide(providers);
2652 util::provide(providers);
2653 print::provide(providers);
2654 super::util::bug::provide(providers);
2655 super::middle::provide(providers);
2656 *providers = ty::query::Providers {
2657 trait_impls_of: trait_def::trait_impls_of_provider,
2658 incoherent_impls: trait_def::incoherent_impls_provider,
2659 const_param_default: consts::const_param_default,
2660 vtable_allocation: vtable::vtable_allocation_provider,
2665 /// A map for the local crate mapping each type to a vector of its
2666 /// inherent impls. This is not meant to be used outside of coherence;
2667 /// rather, you should request the vector for a specific type via
2668 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2669 /// (constructing this map requires touching the entire crate).
2670 #[derive(Clone, Debug, Default, HashStable)]
2671 pub struct CrateInherentImpls {
2672 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2673 pub incoherent_impls: FxHashMap<SimplifiedType, Vec<LocalDefId>>,
2676 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2677 pub struct SymbolName<'tcx> {
2678 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2679 pub name: &'tcx str,
2682 impl<'tcx> SymbolName<'tcx> {
2683 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2685 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2690 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2691 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2692 fmt::Display::fmt(&self.name, fmt)
2696 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2697 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2698 fmt::Display::fmt(&self.name, fmt)
2702 #[derive(Debug, Default, Copy, Clone)]
2703 pub struct FoundRelationships {
2704 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2705 /// obligation, where:
2707 /// * `Foo` is not `Sized`
2708 /// * `(): Foo` may be satisfied
2709 pub self_in_trait: bool,
2710 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2711 /// _>::AssocType = ?T`
2715 /// The constituent parts of a type level constant of kind ADT or array.
2716 #[derive(Copy, Clone, Debug, HashStable)]
2717 pub struct DestructuredConst<'tcx> {
2718 pub variant: Option<VariantIdx>,
2719 pub fields: &'tcx [ty::Const<'tcx>],
2722 // Some types are used a lot. Make sure they don't unintentionally get bigger.
2723 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
2726 use rustc_data_structures::static_assert_size;
2727 // tidy-alphabetical-start
2728 static_assert_size!(PredicateS<'_>, 48);
2729 static_assert_size!(TyS<'_>, 40);
2730 static_assert_size!(WithStableHash<TyS<'_>>, 56);
2731 // tidy-alphabetical-end