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, TypeVisitor};
13 pub use self::AssocItemContainer::*;
14 pub use self::BorrowKind::*;
15 pub use self::IntVarValue::*;
16 pub use self::Variance::*;
17 use crate::metadata::ModChild;
18 use crate::middle::privacy::AccessLevels;
19 use crate::mir::{Body, GeneratorLayout};
20 use crate::traits::{self, Reveal};
22 use crate::ty::fast_reject::SimplifiedType;
23 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
24 use crate::ty::util::Discr;
29 use rustc_attr as attr;
30 use rustc_data_structures::fingerprint::Fingerprint;
31 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
32 use rustc_data_structures::intern::{Interned, WithStableHash};
33 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
34 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
36 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
37 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap};
39 use rustc_macros::HashStable;
40 use rustc_query_system::ich::StableHashingContext;
41 use rustc_session::cstore::CrateStoreDyn;
42 use rustc_span::symbol::{kw, sym, Ident, Symbol};
44 use rustc_target::abi::Align;
49 use std::ops::ControlFlow;
52 pub use crate::ty::diagnostics::*;
53 pub use rustc_type_ir::InferTy::*;
54 pub use rustc_type_ir::*;
56 pub use self::binding::BindingMode;
57 pub use self::binding::BindingMode::*;
58 pub use self::closure::{
59 is_ancestor_or_same_capture, place_to_string_for_capture, BorrowKind, CaptureInfo,
60 CapturedPlace, ClosureKind, MinCaptureInformationMap, MinCaptureList,
61 RootVariableMinCaptureList, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath,
64 pub use self::consts::{
65 Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, Unevaluated, ValTree,
67 pub use self::context::{
68 tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
69 CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorDiagnosticData,
70 GeneratorInteriorTypeCause, GlobalCtxt, Lift, OnDiskCache, TyCtxt, TypeckResults, UserType,
71 UserTypeAnnotationIndex,
73 pub use self::instance::{Instance, InstanceDef};
74 pub use self::list::List;
75 pub use self::parameterized::ParameterizedOverTcx;
76 pub use self::rvalue_scopes::RvalueScopes;
77 pub use self::sty::BoundRegionKind::*;
78 pub use self::sty::RegionKind::*;
79 pub use self::sty::TyKind::*;
81 Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind,
82 CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBinder, EarlyBoundRegion,
83 ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig,
84 GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts, InlineConstSubstsParts, ParamConst,
85 ParamTy, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig,
86 PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut,
87 UpvarSubsts, VarianceDiagInfo,
89 pub use self::trait_def::TraitDef;
100 pub mod inhabitedness;
102 pub mod normalize_erasing_regions;
125 mod structural_impls;
130 pub type RegisteredTools = FxHashSet<Ident>;
133 pub struct ResolverOutputs {
134 pub definitions: rustc_hir::definitions::Definitions,
135 pub cstore: Box<CrateStoreDyn>,
136 pub visibilities: FxHashMap<LocalDefId, Visibility>,
137 /// This field is used to decide whether we should make `PRIVATE_IN_PUBLIC` a hard error.
138 pub has_pub_restricted: bool,
139 pub access_levels: AccessLevels,
140 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
141 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
142 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
143 pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
144 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
145 /// Extern prelude entries. The value is `true` if the entry was introduced
146 /// via `extern crate` item and not `--extern` option or compiler built-in.
147 pub extern_prelude: FxHashMap<Symbol, bool>,
148 pub main_def: Option<MainDefinition>,
149 pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
150 /// A list of proc macro LocalDefIds, written out in the order in which
151 /// they are declared in the static array generated by proc_macro_harness.
152 pub proc_macros: Vec<LocalDefId>,
153 /// Mapping from ident span to path span for paths that don't exist as written, but that
154 /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
155 pub confused_type_with_std_module: FxHashMap<Span, Span>,
156 pub registered_tools: RegisteredTools,
159 #[derive(Clone, Copy, Debug)]
160 pub struct MainDefinition {
161 pub res: Res<ast::NodeId>,
166 impl MainDefinition {
167 pub fn opt_fn_def_id(self) -> Option<DefId> {
168 if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
172 /// The "header" of an impl is everything outside the body: a Self type, a trait
173 /// ref (in the case of a trait impl), and a set of predicates (from the
174 /// bounds / where-clauses).
175 #[derive(Clone, Debug, TypeFoldable)]
176 pub struct ImplHeader<'tcx> {
177 pub impl_def_id: DefId,
178 pub self_ty: Ty<'tcx>,
179 pub trait_ref: Option<TraitRef<'tcx>>,
180 pub predicates: Vec<Predicate<'tcx>>,
183 #[derive(Copy, Clone, Debug, TypeFoldable)]
184 pub enum ImplSubject<'tcx> {
185 Trait(TraitRef<'tcx>),
201 pub enum ImplPolarity {
202 /// `impl Trait for Type`
204 /// `impl !Trait for Type`
206 /// `#[rustc_reservation_impl] impl Trait for Type`
208 /// This is a "stability hack", not a real Rust feature.
209 /// See #64631 for details.
214 /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
215 pub fn flip(&self) -> Option<ImplPolarity> {
217 ImplPolarity::Positive => Some(ImplPolarity::Negative),
218 ImplPolarity::Negative => Some(ImplPolarity::Positive),
219 ImplPolarity::Reservation => None,
224 impl fmt::Display for ImplPolarity {
225 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
227 Self::Positive => f.write_str("positive"),
228 Self::Negative => f.write_str("negative"),
229 Self::Reservation => f.write_str("reservation"),
234 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, Encodable, Decodable, HashStable)]
235 pub enum Visibility {
236 /// Visible everywhere (including in other crates).
238 /// Visible only in the given crate-local module.
240 /// Not visible anywhere in the local crate. This is the visibility of private external items.
244 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
245 pub enum BoundConstness {
248 /// `T: ~const Trait`
250 /// Requires resolving to const only when we are in a const context.
254 impl BoundConstness {
255 /// Reduce `self` and `constness` to two possible combined states instead of four.
256 pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
257 match (constness, self) {
258 (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
260 *this = BoundConstness::NotConst;
261 hir::Constness::NotConst
267 impl fmt::Display for BoundConstness {
268 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
270 Self::NotConst => f.write_str("normal"),
271 Self::ConstIfConst => f.write_str("`~const`"),
288 pub struct ClosureSizeProfileData<'tcx> {
289 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
290 pub before_feature_tys: Ty<'tcx>,
291 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
292 pub after_feature_tys: Ty<'tcx>,
295 pub trait DefIdTree: Copy {
296 fn opt_parent(self, id: DefId) -> Option<DefId>;
300 fn parent(self, id: DefId) -> DefId {
301 match self.opt_parent(id) {
303 // not `unwrap_or_else` to avoid breaking caller tracking
304 None => bug!("{id:?} doesn't have a parent"),
310 fn opt_local_parent(self, id: LocalDefId) -> Option<LocalDefId> {
311 self.opt_parent(id.to_def_id()).map(DefId::expect_local)
316 fn local_parent(self, id: LocalDefId) -> LocalDefId {
317 self.parent(id.to_def_id()).expect_local()
320 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
321 if descendant.krate != ancestor.krate {
325 while descendant != ancestor {
326 match self.opt_parent(descendant) {
327 Some(parent) => descendant = parent,
328 None => return false,
335 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
337 fn opt_parent(self, id: DefId) -> Option<DefId> {
338 self.def_key(id).parent.map(|index| DefId { index, ..id })
343 /// Returns `true` if an item with this visibility is accessible from the given block.
344 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
345 let restriction = match self {
346 // Public items are visible everywhere.
347 Visibility::Public => return true,
348 // Private items from other crates are visible nowhere.
349 Visibility::Invisible => return false,
350 // Restricted items are visible in an arbitrary local module.
351 Visibility::Restricted(other) if other.krate != module.krate => return false,
352 Visibility::Restricted(module) => module,
355 tree.is_descendant_of(module, restriction)
358 /// Returns `true` if this visibility is at least as accessible as the given visibility
359 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
360 let vis_restriction = match vis {
361 Visibility::Public => return self == Visibility::Public,
362 Visibility::Invisible => return true,
363 Visibility::Restricted(module) => module,
366 self.is_accessible_from(vis_restriction, tree)
369 // Returns `true` if this item is visible anywhere in the local crate.
370 pub fn is_visible_locally(self) -> bool {
372 Visibility::Public => true,
373 Visibility::Restricted(def_id) => def_id.is_local(),
374 Visibility::Invisible => false,
378 pub fn is_public(self) -> bool {
379 matches!(self, Visibility::Public)
383 /// The crate variances map is computed during typeck and contains the
384 /// variance of every item in the local crate. You should not use it
385 /// directly, because to do so will make your pass dependent on the
386 /// HIR of every item in the local crate. Instead, use
387 /// `tcx.variances_of()` to get the variance for a *particular*
389 #[derive(HashStable, Debug)]
390 pub struct CrateVariancesMap<'tcx> {
391 /// For each item with generics, maps to a vector of the variance
392 /// of its generics. If an item has no generics, it will have no
394 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
397 // Contains information needed to resolve types and (in the future) look up
398 // the types of AST nodes.
399 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
400 pub struct CReaderCacheKey {
401 pub cnum: Option<CrateNum>,
405 /// Represents a type.
408 /// - This is a very "dumb" struct (with no derives and no `impls`).
409 /// - Values of this type are always interned and thus unique, and are stored
410 /// as an `Interned<TyS>`.
411 /// - `Ty` (which contains a reference to a `Interned<TyS>`) or `Interned<TyS>`
412 /// should be used everywhere instead of `TyS`. In particular, `Ty` has most
413 /// of the relevant methods.
414 #[derive(PartialEq, Eq, PartialOrd, Ord)]
415 #[allow(rustc::usage_of_ty_tykind)]
416 pub(crate) struct TyS<'tcx> {
417 /// This field shouldn't be used directly and may be removed in the future.
418 /// Use `Ty::kind()` instead.
421 /// This field provides fast access to information that is also contained
424 /// This field shouldn't be used directly and may be removed in the future.
425 /// Use `Ty::flags()` instead.
428 /// This field provides fast access to information that is also contained
431 /// This is a kind of confusing thing: it stores the smallest
434 /// (a) the binder itself captures nothing but
435 /// (b) all the late-bound things within the type are captured
436 /// by some sub-binder.
438 /// So, for a type without any late-bound things, like `u32`, this
439 /// will be *innermost*, because that is the innermost binder that
440 /// captures nothing. But for a type `&'D u32`, where `'D` is a
441 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
442 /// -- the binder itself does not capture `D`, but `D` is captured
443 /// by an inner binder.
445 /// We call this concept an "exclusive" binder `D` because all
446 /// De Bruijn indices within the type are contained within `0..D`
448 outer_exclusive_binder: ty::DebruijnIndex,
451 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
452 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
453 static_assert_size!(TyS<'_>, 40);
455 // We are actually storing a stable hash cache next to the type, so let's
456 // also check the full size
457 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
458 static_assert_size!(WithStableHash<TyS<'_>>, 56);
460 /// Use this rather than `TyS`, whenever possible.
461 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
462 #[rustc_diagnostic_item = "Ty"]
463 #[rustc_pass_by_value]
464 pub struct Ty<'tcx>(Interned<'tcx, WithStableHash<TyS<'tcx>>>);
466 // Statics only used for internal testing.
467 pub static BOOL_TY: Ty<'static> = Ty(Interned::new_unchecked(&WithStableHash {
469 stable_hash: Fingerprint::ZERO,
471 const BOOL_TYS: TyS<'static> = TyS {
473 flags: TypeFlags::empty(),
474 outer_exclusive_binder: DebruijnIndex::from_usize(0),
477 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
479 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
483 // The other fields just provide fast access to information that is
484 // also contained in `kind`, so no need to hash them.
487 outer_exclusive_binder: _,
490 kind.hash_stable(hcx, hasher)
494 impl ty::EarlyBoundRegion {
495 /// Does this early bound region have a name? Early bound regions normally
496 /// always have names except when using anonymous lifetimes (`'_`).
497 pub fn has_name(&self) -> bool {
498 self.name != kw::UnderscoreLifetime
502 /// Represents a predicate.
504 /// See comments on `TyS`, which apply here too (albeit for
505 /// `PredicateS`/`Predicate` rather than `TyS`/`Ty`).
507 pub(crate) struct PredicateS<'tcx> {
508 kind: Binder<'tcx, PredicateKind<'tcx>>,
510 /// See the comment for the corresponding field of [TyS].
511 outer_exclusive_binder: ty::DebruijnIndex,
514 // This type is used a lot. Make sure it doesn't unintentionally get bigger.
515 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
516 static_assert_size!(PredicateS<'_>, 56);
518 /// Use this rather than `PredicateS`, whenever possible.
519 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
520 #[rustc_pass_by_value]
521 pub struct Predicate<'tcx>(Interned<'tcx, PredicateS<'tcx>>);
523 impl<'tcx> Predicate<'tcx> {
524 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
526 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
531 pub fn flags(self) -> TypeFlags {
536 pub fn outer_exclusive_binder(self) -> DebruijnIndex {
537 self.0.outer_exclusive_binder
540 /// Flips the polarity of a Predicate.
542 /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
543 pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
546 .map_bound(|kind| match kind {
547 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
548 Some(PredicateKind::Trait(TraitPredicate {
551 polarity: polarity.flip()?,
559 Some(tcx.mk_predicate(kind))
563 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
564 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
568 // The other fields just provide fast access to information that is
569 // also contained in `kind`, so no need to hash them.
571 outer_exclusive_binder: _,
574 kind.hash_stable(hcx, hasher);
578 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
579 #[derive(HashStable, TypeFoldable)]
580 pub enum PredicateKind<'tcx> {
581 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
582 /// the `Self` type of the trait reference and `A`, `B`, and `C`
583 /// would be the type parameters.
584 Trait(TraitPredicate<'tcx>),
587 RegionOutlives(RegionOutlivesPredicate<'tcx>),
590 TypeOutlives(TypeOutlivesPredicate<'tcx>),
592 /// `where <T as TraitRef>::Name == X`, approximately.
593 /// See the `ProjectionPredicate` struct for details.
594 Projection(ProjectionPredicate<'tcx>),
596 /// No syntax: `T` well-formed.
597 WellFormed(GenericArg<'tcx>),
599 /// Trait must be object-safe.
602 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
603 /// for some substitutions `...` and `T` being a closure type.
604 /// Satisfied (or refuted) once we know the closure's kind.
605 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
609 /// This obligation is created most often when we have two
610 /// unresolved type variables and hence don't have enough
611 /// information to process the subtyping obligation yet.
612 Subtype(SubtypePredicate<'tcx>),
614 /// `T1` coerced to `T2`
616 /// Like a subtyping obligation, this is created most often
617 /// when we have two unresolved type variables and hence
618 /// don't have enough information to process the coercion
619 /// obligation yet. At the moment, we actually process coercions
620 /// very much like subtyping and don't handle the full coercion
622 Coerce(CoercePredicate<'tcx>),
624 /// Constant initializer must evaluate successfully.
625 ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
627 /// Constants must be equal. The first component is the const that is expected.
628 ConstEquate(Const<'tcx>, Const<'tcx>),
630 /// Represents a type found in the environment that we can use for implied bounds.
632 /// Only used for Chalk.
633 TypeWellFormedFromEnv(Ty<'tcx>),
636 /// The crate outlives map is computed during typeck and contains the
637 /// outlives of every item in the local crate. You should not use it
638 /// directly, because to do so will make your pass dependent on the
639 /// HIR of every item in the local crate. Instead, use
640 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
642 #[derive(HashStable, Debug)]
643 pub struct CratePredicatesMap<'tcx> {
644 /// For each struct with outlive bounds, maps to a vector of the
645 /// predicate of its outlive bounds. If an item has no outlives
646 /// bounds, it will have no entry.
647 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
650 impl<'tcx> Predicate<'tcx> {
651 /// Performs a substitution suitable for going from a
652 /// poly-trait-ref to supertraits that must hold if that
653 /// poly-trait-ref holds. This is slightly different from a normal
654 /// substitution in terms of what happens with bound regions. See
655 /// lengthy comment below for details.
656 pub fn subst_supertrait(
659 trait_ref: &ty::PolyTraitRef<'tcx>,
660 ) -> Predicate<'tcx> {
661 // The interaction between HRTB and supertraits is not entirely
662 // obvious. Let me walk you (and myself) through an example.
664 // Let's start with an easy case. Consider two traits:
666 // trait Foo<'a>: Bar<'a,'a> { }
667 // trait Bar<'b,'c> { }
669 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
670 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
671 // knew that `Foo<'x>` (for any 'x) then we also know that
672 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
673 // normal substitution.
675 // In terms of why this is sound, the idea is that whenever there
676 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
677 // holds. So if there is an impl of `T:Foo<'a>` that applies to
678 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
681 // Another example to be careful of is this:
683 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
684 // trait Bar1<'b,'c> { }
686 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
687 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
688 // reason is similar to the previous example: any impl of
689 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
690 // basically we would want to collapse the bound lifetimes from
691 // the input (`trait_ref`) and the supertraits.
693 // To achieve this in practice is fairly straightforward. Let's
694 // consider the more complicated scenario:
696 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
697 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
698 // where both `'x` and `'b` would have a DB index of 1.
699 // The substitution from the input trait-ref is therefore going to be
700 // `'a => 'x` (where `'x` has a DB index of 1).
701 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
702 // early-bound parameter and `'b' is a late-bound parameter with a
704 // - If we replace `'a` with `'x` from the input, it too will have
705 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
706 // just as we wanted.
708 // There is only one catch. If we just apply the substitution `'a
709 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
710 // adjust the DB index because we substituting into a binder (it
711 // tries to be so smart...) resulting in `for<'x> for<'b>
712 // Bar1<'x,'b>` (we have no syntax for this, so use your
713 // imagination). Basically the 'x will have DB index of 2 and 'b
714 // will have DB index of 1. Not quite what we want. So we apply
715 // the substitution to the *contents* of the trait reference,
716 // rather than the trait reference itself (put another way, the
717 // substitution code expects equal binding levels in the values
718 // from the substitution and the value being substituted into, and
719 // this trick achieves that).
721 // Working through the second example:
722 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
723 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
724 // We want to end up with:
725 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
727 // 1) We must shift all bound vars in predicate by the length
728 // of trait ref's bound vars. So, we would end up with predicate like
729 // Self: Bar1<'a, '^0.1>
730 // 2) We can then apply the trait substs to this, ending up with
731 // T: Bar1<'^0.0, '^0.1>
732 // 3) Finally, to create the final bound vars, we concatenate the bound
733 // vars of the trait ref with those of the predicate:
735 let bound_pred = self.kind();
736 let pred_bound_vars = bound_pred.bound_vars();
737 let trait_bound_vars = trait_ref.bound_vars();
738 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
740 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
741 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
742 let new = EarlyBinder(shifted_pred).subst(tcx, trait_ref.skip_binder().substs);
743 // 3) ['x] + ['b] -> ['x, 'b]
745 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
746 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
750 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
751 #[derive(HashStable, TypeFoldable)]
752 pub struct TraitPredicate<'tcx> {
753 pub trait_ref: TraitRef<'tcx>,
755 pub constness: BoundConstness,
757 /// If polarity is Positive: we are proving that the trait is implemented.
759 /// If polarity is Negative: we are proving that a negative impl of this trait
760 /// exists. (Note that coherence also checks whether negative impls of supertraits
761 /// exist via a series of predicates.)
763 /// If polarity is Reserved: that's a bug.
764 pub polarity: ImplPolarity,
767 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
769 impl<'tcx> TraitPredicate<'tcx> {
770 pub fn remap_constness(&mut self, tcx: TyCtxt<'tcx>, param_env: &mut ParamEnv<'tcx>) {
771 if unlikely!(Some(self.trait_ref.def_id) == tcx.lang_items().drop_trait()) {
772 // remap without changing constness of this predicate.
773 // this is because `T: ~const Drop` has a different meaning to `T: Drop`
774 // FIXME(fee1-dead): remove this logic after beta bump
775 param_env.remap_constness_with(self.constness)
777 *param_env = param_env.with_constness(self.constness.and(param_env.constness()))
781 /// Remap the constness of this predicate before emitting it for diagnostics.
782 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
783 // this is different to `remap_constness` that callees want to print this predicate
784 // in case of selection errors. `T: ~const Drop` bounds cannot end up here when the
785 // param_env is not const because we it is always satisfied in non-const contexts.
786 if let hir::Constness::NotConst = param_env.constness() {
787 self.constness = ty::BoundConstness::NotConst;
791 pub fn def_id(self) -> DefId {
792 self.trait_ref.def_id
795 pub fn self_ty(self) -> Ty<'tcx> {
796 self.trait_ref.self_ty()
800 pub fn is_const_if_const(self) -> bool {
801 self.constness == BoundConstness::ConstIfConst
805 impl<'tcx> PolyTraitPredicate<'tcx> {
806 pub fn def_id(self) -> DefId {
807 // Ok to skip binder since trait `DefId` does not care about regions.
808 self.skip_binder().def_id()
811 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
812 self.map_bound(|trait_ref| trait_ref.self_ty())
815 /// Remap the constness of this predicate before emitting it for diagnostics.
816 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
817 *self = self.map_bound(|mut p| {
818 p.remap_constness_diag(param_env);
824 pub fn is_const_if_const(self) -> bool {
825 self.skip_binder().is_const_if_const()
829 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
830 #[derive(HashStable, TypeFoldable)]
831 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
832 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
833 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
834 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
835 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
837 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
838 /// whether the `a` type is the type that we should label as "expected" when
839 /// presenting user diagnostics.
840 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
841 #[derive(HashStable, TypeFoldable)]
842 pub struct SubtypePredicate<'tcx> {
843 pub a_is_expected: bool,
847 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
849 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
850 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
851 #[derive(HashStable, TypeFoldable)]
852 pub struct CoercePredicate<'tcx> {
856 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
858 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)]
859 #[derive(HashStable, TypeFoldable)]
860 pub enum Term<'tcx> {
865 impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
866 fn from(ty: Ty<'tcx>) -> Self {
871 impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
872 fn from(c: Const<'tcx>) -> Self {
877 impl<'tcx> Term<'tcx> {
878 pub fn ty(&self) -> Option<Ty<'tcx>> {
879 if let Term::Ty(ty) = self { Some(*ty) } else { None }
881 pub fn ct(&self) -> Option<Const<'tcx>> {
882 if let Term::Const(c) = self { Some(*c) } else { None }
886 /// This kind of predicate has no *direct* correspondent in the
887 /// syntax, but it roughly corresponds to the syntactic forms:
889 /// 1. `T: TraitRef<..., Item = Type>`
890 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
892 /// In particular, form #1 is "desugared" to the combination of a
893 /// normal trait predicate (`T: TraitRef<...>`) and one of these
894 /// predicates. Form #2 is a broader form in that it also permits
895 /// equality between arbitrary types. Processing an instance of
896 /// Form #2 eventually yields one of these `ProjectionPredicate`
897 /// instances to normalize the LHS.
898 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
899 #[derive(HashStable, TypeFoldable)]
900 pub struct ProjectionPredicate<'tcx> {
901 pub projection_ty: ProjectionTy<'tcx>,
902 pub term: Term<'tcx>,
905 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
907 impl<'tcx> PolyProjectionPredicate<'tcx> {
908 /// Returns the `DefId` of the trait of the associated item being projected.
910 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
911 self.skip_binder().projection_ty.trait_def_id(tcx)
914 /// Get the [PolyTraitRef] required for this projection to be well formed.
915 /// Note that for generic associated types the predicates of the associated
916 /// type also need to be checked.
918 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
919 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
920 // `self.0.trait_ref` is permitted to have escaping regions.
921 // This is because here `self` has a `Binder` and so does our
922 // return value, so we are preserving the number of binding
924 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
927 pub fn term(&self) -> Binder<'tcx, Term<'tcx>> {
928 self.map_bound(|predicate| predicate.term)
931 /// The `DefId` of the `TraitItem` for the associated type.
933 /// Note that this is not the `DefId` of the `TraitRef` containing this
934 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
935 pub fn projection_def_id(&self) -> DefId {
936 // Ok to skip binder since trait `DefId` does not care about regions.
937 self.skip_binder().projection_ty.item_def_id
941 pub trait ToPolyTraitRef<'tcx> {
942 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
945 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
946 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
947 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
951 pub trait ToPredicate<'tcx> {
952 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
955 impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
957 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
958 tcx.mk_predicate(self)
962 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
963 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
964 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
968 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
969 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
970 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
974 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
975 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
976 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
980 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
981 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
982 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
986 impl<'tcx> Predicate<'tcx> {
987 pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
988 let predicate = self.kind();
989 match predicate.skip_binder() {
990 PredicateKind::Trait(t) => Some(predicate.rebind(t)),
991 PredicateKind::Projection(..)
992 | PredicateKind::Subtype(..)
993 | PredicateKind::Coerce(..)
994 | PredicateKind::RegionOutlives(..)
995 | PredicateKind::WellFormed(..)
996 | PredicateKind::ObjectSafe(..)
997 | PredicateKind::ClosureKind(..)
998 | PredicateKind::TypeOutlives(..)
999 | PredicateKind::ConstEvaluatable(..)
1000 | PredicateKind::ConstEquate(..)
1001 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1005 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1006 let predicate = self.kind();
1007 match predicate.skip_binder() {
1008 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
1009 PredicateKind::Trait(..)
1010 | PredicateKind::Projection(..)
1011 | PredicateKind::Subtype(..)
1012 | PredicateKind::Coerce(..)
1013 | PredicateKind::RegionOutlives(..)
1014 | PredicateKind::WellFormed(..)
1015 | PredicateKind::ObjectSafe(..)
1016 | PredicateKind::ClosureKind(..)
1017 | PredicateKind::ConstEvaluatable(..)
1018 | PredicateKind::ConstEquate(..)
1019 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1024 /// Represents the bounds declared on a particular set of type
1025 /// parameters. Should eventually be generalized into a flag list of
1026 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
1027 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1028 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1029 /// the `GenericPredicates` are expressed in terms of the bound type
1030 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1031 /// represented a set of bounds for some particular instantiation,
1032 /// meaning that the generic parameters have been substituted with
1036 /// ```ignore (illustrative)
1037 /// struct Foo<T, U: Bar<T>> { ... }
1039 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1040 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1041 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1042 /// [usize:Bar<isize>]]`.
1043 #[derive(Clone, Debug, TypeFoldable)]
1044 pub struct InstantiatedPredicates<'tcx> {
1045 pub predicates: Vec<Predicate<'tcx>>,
1046 pub spans: Vec<Span>,
1049 impl<'tcx> InstantiatedPredicates<'tcx> {
1050 pub fn empty() -> InstantiatedPredicates<'tcx> {
1051 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1054 pub fn is_empty(&self) -> bool {
1055 self.predicates.is_empty()
1071 pub struct OpaqueTypeKey<'tcx> {
1073 pub substs: SubstsRef<'tcx>,
1076 #[derive(Copy, Clone, Debug, TypeFoldable, HashStable, TyEncodable, TyDecodable)]
1077 pub struct OpaqueHiddenType<'tcx> {
1078 /// The span of this particular definition of the opaque type. So
1081 /// ```ignore (incomplete snippet)
1082 /// type Foo = impl Baz;
1083 /// fn bar() -> Foo {
1084 /// // ^^^ This is the span we are looking for!
1088 /// In cases where the fn returns `(impl Trait, impl Trait)` or
1089 /// other such combinations, the result is currently
1090 /// over-approximated, but better than nothing.
1093 /// The type variable that represents the value of the opaque type
1094 /// that we require. In other words, after we compile this function,
1095 /// we will be created a constraint like:
1096 /// ```ignore (pseudo-rust)
1099 /// where `?C` is the value of this type variable. =) It may
1100 /// naturally refer to the type and lifetime parameters in scope
1101 /// in this function, though ultimately it should only reference
1102 /// those that are arguments to `Foo` in the constraint above. (In
1103 /// other words, `?C` should not include `'b`, even though it's a
1104 /// lifetime parameter on `foo`.)
1108 impl<'tcx> OpaqueHiddenType<'tcx> {
1109 pub fn report_mismatch(&self, other: &Self, tcx: TyCtxt<'tcx>) {
1110 // Found different concrete types for the opaque type.
1111 let mut err = tcx.sess.struct_span_err(
1113 "concrete type differs from previous defining opaque type use",
1115 err.span_label(other.span, format!("expected `{}`, got `{}`", self.ty, other.ty));
1116 if self.span == other.span {
1119 "this expression supplies two conflicting concrete types for the same opaque type",
1122 err.span_note(self.span, "previous use here");
1128 rustc_index::newtype_index! {
1129 /// "Universes" are used during type- and trait-checking in the
1130 /// presence of `for<..>` binders to control what sets of names are
1131 /// visible. Universes are arranged into a tree: the root universe
1132 /// contains names that are always visible. Each child then adds a new
1133 /// set of names that are visible, in addition to those of its parent.
1134 /// We say that the child universe "extends" the parent universe with
1137 /// To make this more concrete, consider this program:
1139 /// ```ignore (illustrative)
1141 /// fn bar<T>(x: T) {
1142 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1146 /// The struct name `Foo` is in the root universe U0. But the type
1147 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1148 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1149 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1150 /// region `'a` is in a universe U2 that extends U1, because we can
1151 /// name it inside the fn type but not outside.
1153 /// Universes are used to do type- and trait-checking around these
1154 /// "forall" binders (also called **universal quantification**). The
1155 /// idea is that when, in the body of `bar`, we refer to `T` as a
1156 /// type, we aren't referring to any type in particular, but rather a
1157 /// kind of "fresh" type that is distinct from all other types we have
1158 /// actually declared. This is called a **placeholder** type, and we
1159 /// use universes to talk about this. In other words, a type name in
1160 /// universe 0 always corresponds to some "ground" type that the user
1161 /// declared, but a type name in a non-zero universe is a placeholder
1162 /// type -- an idealized representative of "types in general" that we
1163 /// use for checking generic functions.
1164 pub struct UniverseIndex {
1166 DEBUG_FORMAT = "U{}",
1170 impl UniverseIndex {
1171 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1173 /// Returns the "next" universe index in order -- this new index
1174 /// is considered to extend all previous universes. This
1175 /// corresponds to entering a `forall` quantifier. So, for
1176 /// example, suppose we have this type in universe `U`:
1178 /// ```ignore (illustrative)
1179 /// for<'a> fn(&'a u32)
1182 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1183 /// new universe that extends `U` -- in this new universe, we can
1184 /// name the region `'a`, but that region was not nameable from
1185 /// `U` because it was not in scope there.
1186 pub fn next_universe(self) -> UniverseIndex {
1187 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1190 /// Returns `true` if `self` can name a name from `other` -- in other words,
1191 /// if the set of names in `self` is a superset of those in
1192 /// `other` (`self >= other`).
1193 pub fn can_name(self, other: UniverseIndex) -> bool {
1194 self.private >= other.private
1197 /// Returns `true` if `self` cannot name some names from `other` -- in other
1198 /// words, if the set of names in `self` is a strict subset of
1199 /// those in `other` (`self < other`).
1200 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1201 self.private < other.private
1205 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1206 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1207 /// regions/types/consts within the same universe simply have an unknown relationship to one
1209 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1210 pub struct Placeholder<T> {
1211 pub universe: UniverseIndex,
1215 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1217 T: HashStable<StableHashingContext<'a>>,
1219 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1220 self.universe.hash_stable(hcx, hasher);
1221 self.name.hash_stable(hcx, hasher);
1225 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1227 pub type PlaceholderType = Placeholder<BoundVar>;
1229 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1230 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1231 pub struct BoundConst<'tcx> {
1236 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1238 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1239 /// the `DefId` of the generic parameter it instantiates.
1241 /// This is used to avoid calls to `type_of` for const arguments during typeck
1242 /// which cause cycle errors.
1247 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1248 /// // ^ const parameter
1252 /// fn foo<const M: u8>(&self) -> usize { 42 }
1253 /// // ^ const parameter
1258 /// let _b = a.foo::<{ 3 + 7 }>();
1259 /// // ^^^^^^^^^ const argument
1263 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1264 /// which `foo` is used until we know the type of `a`.
1266 /// We only know the type of `a` once we are inside of `typeck(main)`.
1267 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1268 /// requires us to evaluate the const argument.
1270 /// To evaluate that const argument we need to know its type,
1271 /// which we would get using `type_of(const_arg)`. This requires us to
1272 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1273 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1274 /// which results in a cycle.
1276 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1278 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1279 /// already resolved `foo` so we know which const parameter this argument instantiates.
1280 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1281 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1282 /// trivial to compute.
1284 /// If we now want to use that constant in a place which potentially needs its type
1285 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1286 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1287 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1288 /// to get the type of `did`.
1289 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1290 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1291 #[derive(Hash, HashStable)]
1292 pub struct WithOptConstParam<T> {
1294 /// The `DefId` of the corresponding generic parameter in case `did` is
1295 /// a const argument.
1297 /// Note that even if `did` is a const argument, this may still be `None`.
1298 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1299 /// to potentially update `param_did` in the case it is `None`.
1300 pub const_param_did: Option<DefId>,
1303 impl<T> WithOptConstParam<T> {
1304 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1306 pub fn unknown(did: T) -> WithOptConstParam<T> {
1307 WithOptConstParam { did, const_param_did: None }
1311 impl WithOptConstParam<LocalDefId> {
1312 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1313 /// `None` otherwise.
1315 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1316 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1319 /// In case `self` is unknown but `self.did` is a const argument, this returns
1320 /// a `WithOptConstParam` with the correct `const_param_did`.
1322 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1323 if self.const_param_did.is_none() {
1324 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1325 return Some(WithOptConstParam { did: self.did, const_param_did });
1332 pub fn to_global(self) -> WithOptConstParam<DefId> {
1333 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1336 pub fn def_id_for_type_of(self) -> DefId {
1337 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1341 impl WithOptConstParam<DefId> {
1342 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1345 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1348 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1349 if let Some(param_did) = self.const_param_did {
1350 if let Some(did) = self.did.as_local() {
1351 return Some((did, param_did));
1358 pub fn is_local(self) -> bool {
1362 pub fn def_id_for_type_of(self) -> DefId {
1363 self.const_param_did.unwrap_or(self.did)
1367 /// When type checking, we use the `ParamEnv` to track
1368 /// details about the set of where-clauses that are in scope at this
1369 /// particular point.
1370 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1371 pub struct ParamEnv<'tcx> {
1372 /// This packs both caller bounds and the reveal enum into one pointer.
1374 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1375 /// basically the set of bounds on the in-scope type parameters, translated
1376 /// into `Obligation`s, and elaborated and normalized.
1378 /// Use the `caller_bounds()` method to access.
1380 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1381 /// want `Reveal::All`.
1383 /// Note: This is packed, use the reveal() method to access it.
1384 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
1387 #[derive(Copy, Clone)]
1389 reveal: traits::Reveal,
1390 constness: hir::Constness,
1393 unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
1394 const BITS: usize = 2;
1396 fn into_usize(self) -> usize {
1398 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
1399 Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
1400 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
1401 Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
1405 unsafe fn from_usize(ptr: usize) -> Self {
1407 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1408 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
1409 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
1410 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
1411 _ => std::hint::unreachable_unchecked(),
1416 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1417 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1418 f.debug_struct("ParamEnv")
1419 .field("caller_bounds", &self.caller_bounds())
1420 .field("reveal", &self.reveal())
1421 .field("constness", &self.constness())
1426 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1427 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1428 self.caller_bounds().hash_stable(hcx, hasher);
1429 self.reveal().hash_stable(hcx, hasher);
1430 self.constness().hash_stable(hcx, hasher);
1434 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1435 fn try_super_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
1438 ) -> Result<Self, F::Error> {
1440 self.caller_bounds().try_fold_with(folder)?,
1441 self.reveal().try_fold_with(folder)?,
1442 self.constness().try_fold_with(folder)?,
1446 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1447 self.caller_bounds().visit_with(visitor)?;
1448 self.reveal().visit_with(visitor)?;
1449 self.constness().visit_with(visitor)
1453 impl<'tcx> ParamEnv<'tcx> {
1454 /// Construct a trait environment suitable for contexts where
1455 /// there are no where-clauses in scope. Hidden types (like `impl
1456 /// Trait`) are left hidden, so this is suitable for ordinary
1459 pub fn empty() -> Self {
1460 Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
1464 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1465 self.packed.pointer()
1469 pub fn reveal(self) -> traits::Reveal {
1470 self.packed.tag().reveal
1474 pub fn constness(self) -> hir::Constness {
1475 self.packed.tag().constness
1479 pub fn is_const(self) -> bool {
1480 self.packed.tag().constness == hir::Constness::Const
1483 /// Construct a trait environment with no where-clauses in scope
1484 /// where the values of all `impl Trait` and other hidden types
1485 /// are revealed. This is suitable for monomorphized, post-typeck
1486 /// environments like codegen or doing optimizations.
1488 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1489 /// or invoke `param_env.with_reveal_all()`.
1491 pub fn reveal_all() -> Self {
1492 Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
1495 /// Construct a trait environment with the given set of predicates.
1498 caller_bounds: &'tcx List<Predicate<'tcx>>,
1500 constness: hir::Constness,
1502 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
1505 pub fn with_user_facing(mut self) -> Self {
1506 self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
1511 pub fn with_constness(mut self, constness: hir::Constness) -> Self {
1512 self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
1517 pub fn with_const(mut self) -> Self {
1518 self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
1523 pub fn without_const(mut self) -> Self {
1524 self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
1529 pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
1530 *self = self.with_constness(constness.and(self.constness()))
1533 /// Returns a new parameter environment with the same clauses, but
1534 /// which "reveals" the true results of projections in all cases
1535 /// (even for associated types that are specializable). This is
1536 /// the desired behavior during codegen and certain other special
1537 /// contexts; normally though we want to use `Reveal::UserFacing`,
1538 /// which is the default.
1539 /// All opaque types in the caller_bounds of the `ParamEnv`
1540 /// will be normalized to their underlying types.
1541 /// See PR #65989 and issue #65918 for more details
1542 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1543 if self.packed.tag().reveal == traits::Reveal::All {
1548 tcx.normalize_opaque_types(self.caller_bounds()),
1554 /// Returns this same environment but with no caller bounds.
1556 pub fn without_caller_bounds(self) -> Self {
1557 Self::new(List::empty(), self.reveal(), self.constness())
1560 /// Creates a suitable environment in which to perform trait
1561 /// queries on the given value. When type-checking, this is simply
1562 /// the pair of the environment plus value. But when reveal is set to
1563 /// All, then if `value` does not reference any type parameters, we will
1564 /// pair it with the empty environment. This improves caching and is generally
1567 /// N.B., we preserve the environment when type-checking because it
1568 /// is possible for the user to have wacky where-clauses like
1569 /// `where Box<u32>: Copy`, which are clearly never
1570 /// satisfiable. We generally want to behave as if they were true,
1571 /// although the surrounding function is never reachable.
1572 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1573 match self.reveal() {
1574 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1577 if value.is_global() {
1578 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1580 ParamEnvAnd { param_env: self, value }
1587 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1588 // the constness of trait bounds is being propagated correctly.
1589 impl<'tcx> PolyTraitRef<'tcx> {
1591 pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
1592 self.map_bound(|trait_ref| ty::TraitPredicate {
1595 polarity: ty::ImplPolarity::Positive,
1600 pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
1601 self.with_constness(BoundConstness::NotConst)
1605 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1606 pub struct ParamEnvAnd<'tcx, T> {
1607 pub param_env: ParamEnv<'tcx>,
1611 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1612 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1613 (self.param_env, self.value)
1617 pub fn without_const(mut self) -> Self {
1618 self.param_env = self.param_env.without_const();
1623 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1625 T: HashStable<StableHashingContext<'a>>,
1627 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1628 let ParamEnvAnd { ref param_env, ref value } = *self;
1630 param_env.hash_stable(hcx, hasher);
1631 value.hash_stable(hcx, hasher);
1635 #[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
1636 pub struct Destructor {
1637 /// The `DefId` of the destructor method
1639 /// The constness of the destructor method
1640 pub constness: hir::Constness,
1644 #[derive(HashStable, TyEncodable, TyDecodable)]
1645 pub struct VariantFlags: u32 {
1646 const NO_VARIANT_FLAGS = 0;
1647 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1648 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1649 /// Indicates whether this variant was obtained as part of recovering from
1650 /// a syntactic error. May be incomplete or bogus.
1651 const IS_RECOVERED = 1 << 1;
1655 /// Definition of a variant -- a struct's fields or an enum variant.
1656 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1657 pub struct VariantDef {
1658 /// `DefId` that identifies the variant itself.
1659 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1661 /// `DefId` that identifies the variant's constructor.
1662 /// If this variant is a struct variant, then this is `None`.
1663 pub ctor_def_id: Option<DefId>,
1664 /// Variant or struct name.
1666 /// Discriminant of this variant.
1667 pub discr: VariantDiscr,
1668 /// Fields of this variant.
1669 pub fields: Vec<FieldDef>,
1670 /// Type of constructor of variant.
1671 pub ctor_kind: CtorKind,
1672 /// Flags of the variant (e.g. is field list non-exhaustive)?
1673 flags: VariantFlags,
1677 /// Creates a new `VariantDef`.
1679 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1680 /// represents an enum variant).
1682 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1683 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1685 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1686 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1687 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1688 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1689 /// built-in trait), and we do not want to load attributes twice.
1691 /// If someone speeds up attribute loading to not be a performance concern, they can
1692 /// remove this hack and use the constructor `DefId` everywhere.
1695 variant_did: Option<DefId>,
1696 ctor_def_id: Option<DefId>,
1697 discr: VariantDiscr,
1698 fields: Vec<FieldDef>,
1699 ctor_kind: CtorKind,
1703 is_field_list_non_exhaustive: bool,
1706 "VariantDef::new(name = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1707 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1708 name, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1711 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1712 if is_field_list_non_exhaustive {
1713 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1717 flags |= VariantFlags::IS_RECOVERED;
1721 def_id: variant_did.unwrap_or(parent_did),
1731 /// Is this field list non-exhaustive?
1733 pub fn is_field_list_non_exhaustive(&self) -> bool {
1734 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1737 /// Was this variant obtained as part of recovering from a syntactic error?
1739 pub fn is_recovered(&self) -> bool {
1740 self.flags.intersects(VariantFlags::IS_RECOVERED)
1743 /// Computes the `Ident` of this variant by looking up the `Span`
1744 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1745 Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1749 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1750 pub enum VariantDiscr {
1751 /// Explicit value for this variant, i.e., `X = 123`.
1752 /// The `DefId` corresponds to the embedded constant.
1755 /// The previous variant's discriminant plus one.
1756 /// For efficiency reasons, the distance from the
1757 /// last `Explicit` discriminant is being stored,
1758 /// or `0` for the first variant, if it has none.
1762 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1763 pub struct FieldDef {
1766 pub vis: Visibility,
1770 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1771 pub struct ReprFlags: u8 {
1772 const IS_C = 1 << 0;
1773 const IS_SIMD = 1 << 1;
1774 const IS_TRANSPARENT = 1 << 2;
1775 // Internal only for now. If true, don't reorder fields.
1776 const IS_LINEAR = 1 << 3;
1777 // If true, don't expose any niche to type's context.
1778 const HIDE_NICHE = 1 << 4;
1779 // If true, the type's layout can be randomized using
1780 // the seed stored in `ReprOptions.layout_seed`
1781 const RANDOMIZE_LAYOUT = 1 << 5;
1782 // Any of these flags being set prevent field reordering optimisation.
1783 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
1784 | ReprFlags::IS_SIMD.bits
1785 | ReprFlags::IS_LINEAR.bits;
1789 /// Represents the repr options provided by the user,
1790 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
1791 pub struct ReprOptions {
1792 pub int: Option<attr::IntType>,
1793 pub align: Option<Align>,
1794 pub pack: Option<Align>,
1795 pub flags: ReprFlags,
1796 /// The seed to be used for randomizing a type's layout
1798 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
1799 /// be the "most accurate" hash as it'd encompass the item and crate
1800 /// hash without loss, but it does pay the price of being larger.
1801 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
1802 /// purposes (primarily `-Z randomize-layout`)
1803 pub field_shuffle_seed: u64,
1807 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1808 let mut flags = ReprFlags::empty();
1809 let mut size = None;
1810 let mut max_align: Option<Align> = None;
1811 let mut min_pack: Option<Align> = None;
1813 // Generate a deterministically-derived seed from the item's path hash
1814 // to allow for cross-crate compilation to actually work
1815 let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
1817 // If the user defined a custom seed for layout randomization, xor the item's
1818 // path hash with the user defined seed, this will allowing determinism while
1819 // still allowing users to further randomize layout generation for e.g. fuzzing
1820 if let Some(user_seed) = tcx.sess.opts.debugging_opts.layout_seed {
1821 field_shuffle_seed ^= user_seed;
1824 for attr in tcx.get_attrs(did, sym::repr) {
1825 for r in attr::parse_repr_attr(&tcx.sess, attr) {
1826 flags.insert(match r {
1827 attr::ReprC => ReprFlags::IS_C,
1828 attr::ReprPacked(pack) => {
1829 let pack = Align::from_bytes(pack as u64).unwrap();
1830 min_pack = Some(if let Some(min_pack) = min_pack {
1837 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1838 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
1839 attr::ReprSimd => ReprFlags::IS_SIMD,
1840 attr::ReprInt(i) => {
1844 attr::ReprAlign(align) => {
1845 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
1852 // If `-Z randomize-layout` was enabled for the type definition then we can
1853 // consider performing layout randomization
1854 if tcx.sess.opts.debugging_opts.randomize_layout {
1855 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1858 // This is here instead of layout because the choice must make it into metadata.
1859 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
1860 flags.insert(ReprFlags::IS_LINEAR);
1863 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1867 pub fn simd(&self) -> bool {
1868 self.flags.contains(ReprFlags::IS_SIMD)
1872 pub fn c(&self) -> bool {
1873 self.flags.contains(ReprFlags::IS_C)
1877 pub fn packed(&self) -> bool {
1882 pub fn transparent(&self) -> bool {
1883 self.flags.contains(ReprFlags::IS_TRANSPARENT)
1887 pub fn linear(&self) -> bool {
1888 self.flags.contains(ReprFlags::IS_LINEAR)
1892 pub fn hide_niche(&self) -> bool {
1893 self.flags.contains(ReprFlags::HIDE_NICHE)
1896 /// Returns the discriminant type, given these `repr` options.
1897 /// This must only be called on enums!
1898 pub fn discr_type(&self) -> attr::IntType {
1899 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1902 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
1903 /// layout" optimizations, such as representing `Foo<&T>` as a
1905 pub fn inhibit_enum_layout_opt(&self) -> bool {
1906 self.c() || self.int.is_some()
1909 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
1910 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
1911 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
1912 if let Some(pack) = self.pack {
1913 if pack.bytes() == 1 {
1918 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
1921 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
1922 /// was enabled for its declaration crate
1923 pub fn can_randomize_type_layout(&self) -> bool {
1924 !self.inhibit_struct_field_reordering_opt()
1925 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
1928 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
1929 pub fn inhibit_union_abi_opt(&self) -> bool {
1934 impl<'tcx> FieldDef {
1935 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
1936 /// typically obtained via the second field of [`TyKind::Adt`].
1937 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
1938 tcx.bound_type_of(self.did).subst(tcx, subst)
1941 /// Computes the `Ident` of this variant by looking up the `Span`
1942 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1943 Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
1947 pub type Attributes<'tcx> = impl Iterator<Item = &'tcx ast::Attribute>;
1948 #[derive(Debug, PartialEq, Eq)]
1949 pub enum ImplOverlapKind {
1950 /// These impls are always allowed to overlap.
1952 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1955 /// These impls are allowed to overlap, but that raises
1956 /// an issue #33140 future-compatibility warning.
1958 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
1959 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
1961 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
1962 /// that difference, making what reduces to the following set of impls:
1964 /// ```compile_fail,(E0119)
1966 /// impl Trait for dyn Send + Sync {}
1967 /// impl Trait for dyn Sync + Send {}
1970 /// Obviously, once we made these types be identical, that code causes a coherence
1971 /// error and a fairly big headache for us. However, luckily for us, the trait
1972 /// `Trait` used in this case is basically a marker trait, and therefore having
1973 /// overlapping impls for it is sound.
1975 /// To handle this, we basically regard the trait as a marker trait, with an additional
1976 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
1977 /// it has the following restrictions:
1979 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
1981 /// 2. The trait-ref of both impls must be equal.
1982 /// 3. The trait-ref of both impls must be a trait object type consisting only of
1984 /// 4. Neither of the impls can have any where-clauses.
1986 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
1990 impl<'tcx> TyCtxt<'tcx> {
1991 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1992 self.typeck(self.hir().body_owner_def_id(body))
1995 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1996 self.associated_items(id)
1997 .in_definition_order()
1998 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
2001 /// Look up the name of a definition across crates. This does not look at HIR.
2002 pub fn opt_item_name(self, def_id: DefId) -> Option<Symbol> {
2003 if let Some(cnum) = def_id.as_crate_root() {
2004 Some(self.crate_name(cnum))
2006 let def_key = self.def_key(def_id);
2007 match def_key.disambiguated_data.data {
2008 // The name of a constructor is that of its parent.
2009 rustc_hir::definitions::DefPathData::Ctor => self
2010 .opt_item_name(DefId { krate: def_id.krate, index: def_key.parent.unwrap() }),
2011 // The name of opaque types only exists in HIR.
2012 rustc_hir::definitions::DefPathData::ImplTrait
2013 if let Some(def_id) = def_id.as_local() =>
2014 self.hir().opt_name(self.hir().local_def_id_to_hir_id(def_id)),
2015 _ => def_key.get_opt_name(),
2020 /// Look up the name of a definition across crates. This does not look at HIR.
2022 /// This method will ICE if the corresponding item does not have a name. In these cases, use
2023 /// [`opt_item_name`] instead.
2025 /// [`opt_item_name`]: Self::opt_item_name
2026 pub fn item_name(self, id: DefId) -> Symbol {
2027 self.opt_item_name(id).unwrap_or_else(|| {
2028 bug!("item_name: no name for {:?}", self.def_path(id));
2032 /// Look up the name and span of a definition.
2034 /// See [`item_name`][Self::item_name] for more information.
2035 pub fn opt_item_ident(self, def_id: DefId) -> Option<Ident> {
2036 let def = self.opt_item_name(def_id)?;
2039 .and_then(|id| self.def_ident_span(id))
2040 .unwrap_or(rustc_span::DUMMY_SP);
2041 Some(Ident::new(def, span))
2044 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2045 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2046 Some(self.associated_item(def_id))
2052 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
2053 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
2056 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2060 .position(|field| self.hygienic_eq(ident, field.ident(self), variant.def_id))
2063 /// Returns `true` if the impls are the same polarity and the trait either
2064 /// has no items or is annotated `#[marker]` and prevents item overrides.
2065 pub fn impls_are_allowed_to_overlap(
2069 ) -> Option<ImplOverlapKind> {
2070 // If either trait impl references an error, they're allowed to overlap,
2071 // as one of them essentially doesn't exist.
2072 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2073 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2075 return Some(ImplOverlapKind::Permitted { marker: false });
2078 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2079 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2080 // `#[rustc_reservation_impl]` impls don't overlap with anything
2082 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2085 return Some(ImplOverlapKind::Permitted { marker: false });
2087 (ImplPolarity::Positive, ImplPolarity::Negative)
2088 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2089 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2091 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2096 (ImplPolarity::Positive, ImplPolarity::Positive)
2097 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2100 let is_marker_overlap = {
2101 let is_marker_impl = |def_id: DefId| -> bool {
2102 let trait_ref = self.impl_trait_ref(def_id);
2103 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2105 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2108 if is_marker_overlap {
2110 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2113 Some(ImplOverlapKind::Permitted { marker: true })
2115 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2116 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2117 if self_ty1 == self_ty2 {
2119 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2122 return Some(ImplOverlapKind::Issue33140);
2125 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2126 def_id1, def_id2, self_ty1, self_ty2
2132 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2137 /// Returns `ty::VariantDef` if `res` refers to a struct,
2138 /// or variant or their constructors, panics otherwise.
2139 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2141 Res::Def(DefKind::Variant, did) => {
2142 let enum_did = self.parent(did);
2143 self.adt_def(enum_did).variant_with_id(did)
2145 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2146 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2147 let variant_did = self.parent(variant_ctor_did);
2148 let enum_did = self.parent(variant_did);
2149 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2151 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2152 let struct_did = self.parent(ctor_did);
2153 self.adt_def(struct_did).non_enum_variant()
2155 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2159 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2160 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2162 ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
2164 | DefKind::Static(..)
2165 | DefKind::AssocConst
2167 | DefKind::AnonConst
2168 | DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
2169 // If the caller wants `mir_for_ctfe` of a function they should not be using
2170 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2172 assert_eq!(def.const_param_did, None);
2173 self.optimized_mir(def.did)
2176 ty::InstanceDef::VtableShim(..)
2177 | ty::InstanceDef::ReifyShim(..)
2178 | ty::InstanceDef::Intrinsic(..)
2179 | ty::InstanceDef::FnPtrShim(..)
2180 | ty::InstanceDef::Virtual(..)
2181 | ty::InstanceDef::ClosureOnceShim { .. }
2182 | ty::InstanceDef::DropGlue(..)
2183 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2187 // FIXME(@lcnr): Remove this function.
2188 pub fn get_attrs_unchecked(self, did: DefId) -> &'tcx [ast::Attribute] {
2189 if let Some(did) = did.as_local() {
2190 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2192 self.item_attrs(did)
2196 /// Gets all attributes with the given name.
2197 pub fn get_attrs(self, did: DefId, attr: Symbol) -> ty::Attributes<'tcx> {
2198 let filter_fn = move |a: &&ast::Attribute| a.has_name(attr);
2199 if let Some(did) = did.as_local() {
2200 self.hir().attrs(self.hir().local_def_id_to_hir_id(did)).iter().filter(filter_fn)
2201 } else if cfg!(debug_assertions) && rustc_feature::is_builtin_only_local(attr) {
2202 bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr);
2204 self.item_attrs(did).iter().filter(filter_fn)
2208 pub fn get_attr(self, did: DefId, attr: Symbol) -> Option<&'tcx ast::Attribute> {
2209 self.get_attrs(did, attr).next()
2212 /// Determines whether an item is annotated with an attribute.
2213 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2214 if cfg!(debug_assertions) && !did.is_local() && rustc_feature::is_builtin_only_local(attr) {
2215 bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr);
2217 self.get_attrs(did, attr).next().is_some()
2221 /// Returns `true` if this is an `auto trait`.
2222 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2223 self.trait_def(trait_def_id).has_auto_impl
2226 /// Returns layout of a generator. Layout might be unavailable if the
2227 /// generator is tainted by errors.
2228 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2229 self.optimized_mir(def_id).generator_layout()
2232 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2233 /// If it implements no trait, returns `None`.
2234 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2235 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2238 /// If the given `DefId` describes a method belonging to an impl, returns the
2239 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2240 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2241 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
2242 TraitContainer(_) => None,
2243 ImplContainer(def_id) => Some(def_id),
2247 /// If the given `DefId` belongs to a trait that was automatically derived, returns `true`.
2248 pub fn is_builtin_derive(self, def_id: DefId) -> bool {
2249 self.has_attr(def_id, sym::automatically_derived)
2252 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2253 /// with the name of the crate containing the impl.
2254 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2255 if let Some(impl_did) = impl_did.as_local() {
2256 Ok(self.def_span(impl_did))
2258 Err(self.crate_name(impl_did.krate))
2262 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2263 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2264 /// definition's parent/scope to perform comparison.
2265 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2266 // We could use `Ident::eq` here, but we deliberately don't. The name
2267 // comparison fails frequently, and we want to avoid the expensive
2268 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2269 use_name.name == def_name.name
2273 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2276 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2277 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2281 pub fn adjust_ident_and_get_scope(
2286 ) -> (Ident, DefId) {
2289 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2290 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2291 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2295 pub fn is_object_safe(self, key: DefId) -> bool {
2296 self.object_safety_violations(key).is_empty()
2300 pub fn is_const_fn_raw(self, def_id: DefId) -> bool {
2301 matches!(self.def_kind(def_id), DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..))
2302 && self.impl_constness(def_id) == hir::Constness::Const
2306 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
2307 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
2308 let def_id = def_id.as_local()?;
2309 if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) {
2310 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2311 return match opaque_ty.origin {
2312 hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
2315 hir::OpaqueTyOrigin::TyAlias => None,
2322 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2324 ast::IntTy::Isize => IntTy::Isize,
2325 ast::IntTy::I8 => IntTy::I8,
2326 ast::IntTy::I16 => IntTy::I16,
2327 ast::IntTy::I32 => IntTy::I32,
2328 ast::IntTy::I64 => IntTy::I64,
2329 ast::IntTy::I128 => IntTy::I128,
2333 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2335 ast::UintTy::Usize => UintTy::Usize,
2336 ast::UintTy::U8 => UintTy::U8,
2337 ast::UintTy::U16 => UintTy::U16,
2338 ast::UintTy::U32 => UintTy::U32,
2339 ast::UintTy::U64 => UintTy::U64,
2340 ast::UintTy::U128 => UintTy::U128,
2344 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2346 ast::FloatTy::F32 => FloatTy::F32,
2347 ast::FloatTy::F64 => FloatTy::F64,
2351 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2353 IntTy::Isize => ast::IntTy::Isize,
2354 IntTy::I8 => ast::IntTy::I8,
2355 IntTy::I16 => ast::IntTy::I16,
2356 IntTy::I32 => ast::IntTy::I32,
2357 IntTy::I64 => ast::IntTy::I64,
2358 IntTy::I128 => ast::IntTy::I128,
2362 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2364 UintTy::Usize => ast::UintTy::Usize,
2365 UintTy::U8 => ast::UintTy::U8,
2366 UintTy::U16 => ast::UintTy::U16,
2367 UintTy::U32 => ast::UintTy::U32,
2368 UintTy::U64 => ast::UintTy::U64,
2369 UintTy::U128 => ast::UintTy::U128,
2373 pub fn provide(providers: &mut ty::query::Providers) {
2374 closure::provide(providers);
2375 context::provide(providers);
2376 erase_regions::provide(providers);
2377 layout::provide(providers);
2378 util::provide(providers);
2379 print::provide(providers);
2380 super::util::bug::provide(providers);
2381 super::middle::provide(providers);
2382 *providers = ty::query::Providers {
2383 trait_impls_of: trait_def::trait_impls_of_provider,
2384 incoherent_impls: trait_def::incoherent_impls_provider,
2385 type_uninhabited_from: inhabitedness::type_uninhabited_from,
2386 const_param_default: consts::const_param_default,
2387 vtable_allocation: vtable::vtable_allocation_provider,
2392 /// A map for the local crate mapping each type to a vector of its
2393 /// inherent impls. This is not meant to be used outside of coherence;
2394 /// rather, you should request the vector for a specific type via
2395 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2396 /// (constructing this map requires touching the entire crate).
2397 #[derive(Clone, Debug, Default, HashStable)]
2398 pub struct CrateInherentImpls {
2399 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2400 pub incoherent_impls: FxHashMap<SimplifiedType, Vec<LocalDefId>>,
2403 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2404 pub struct SymbolName<'tcx> {
2405 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2406 pub name: &'tcx str,
2409 impl<'tcx> SymbolName<'tcx> {
2410 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2412 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2417 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2418 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2419 fmt::Display::fmt(&self.name, fmt)
2423 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2424 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2425 fmt::Display::fmt(&self.name, fmt)
2429 #[derive(Debug, Default, Copy, Clone)]
2430 pub struct FoundRelationships {
2431 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2432 /// obligation, where:
2434 /// * `Foo` is not `Sized`
2435 /// * `(): Foo` may be satisfied
2436 pub self_in_trait: bool,
2437 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2438 /// _>::AssocType = ?T`