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 ructc-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::*;
22 use crate::metadata::ModChild;
23 use crate::mir::{Body, GeneratorLayout};
24 use crate::traits::{self, Reveal};
26 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
27 use crate::ty::util::Discr;
29 use rustc_attr as attr;
30 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
31 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
32 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
34 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
35 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap, CRATE_DEF_INDEX};
37 use rustc_macros::HashStable;
38 use rustc_query_system::ich::StableHashingContext;
39 use rustc_session::cstore::CrateStoreDyn;
40 use rustc_span::symbol::{kw, Ident, Symbol};
41 use rustc_span::{sym, Span};
42 use rustc_target::abi::Align;
44 use std::cmp::Ordering;
45 use std::collections::BTreeMap;
46 use std::hash::{Hash, Hasher};
47 use std::ops::ControlFlow;
48 use std::{fmt, ptr, str};
50 pub use crate::ty::diagnostics::*;
51 pub use rustc_type_ir::InferTy::*;
52 pub use rustc_type_ir::*;
54 pub use self::binding::BindingMode;
55 pub use self::binding::BindingMode::*;
56 pub use self::closure::{
57 is_ancestor_or_same_capture, place_to_string_for_capture, BorrowKind, CaptureInfo,
58 CapturedPlace, ClosureKind, MinCaptureInformationMap, MinCaptureList,
59 RootVariableMinCaptureList, UpvarBorrow, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap,
60 UpvarPath, CAPTURE_STRUCT_LOCAL,
62 pub use self::consts::{Const, ConstInt, ConstKind, InferConst, ScalarInt, Unevaluated, ValTree};
63 pub use self::context::{
64 tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
65 CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorInteriorTypeCause, GlobalCtxt,
66 Lift, OnDiskCache, TyCtxt, TypeckResults, UserType, UserTypeAnnotationIndex,
68 pub use self::instance::{Instance, InstanceDef};
69 pub use self::list::List;
70 pub use self::sty::BoundRegionKind::*;
71 pub use self::sty::RegionKind::*;
72 pub use self::sty::TyKind::*;
74 Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind,
75 CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBoundRegion,
76 ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig,
77 GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts, InlineConstSubstsParts, ParamConst,
78 ParamTy, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig,
79 PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut,
80 UpvarSubsts, VarianceDiagInfo,
82 pub use self::trait_def::TraitDef;
93 pub mod inhabitedness;
95 pub mod normalize_erasing_regions;
116 mod structural_impls;
122 pub struct ResolverOutputs {
123 pub definitions: rustc_hir::definitions::Definitions,
124 pub cstore: Box<CrateStoreDyn>,
125 pub visibilities: FxHashMap<LocalDefId, Visibility>,
126 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
127 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
128 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
129 pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
130 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
131 /// Extern prelude entries. The value is `true` if the entry was introduced
132 /// via `extern crate` item and not `--extern` option or compiler built-in.
133 pub extern_prelude: FxHashMap<Symbol, bool>,
134 pub main_def: Option<MainDefinition>,
135 pub trait_impls: BTreeMap<DefId, Vec<LocalDefId>>,
136 /// A list of proc macro LocalDefIds, written out in the order in which
137 /// they are declared in the static array generated by proc_macro_harness.
138 pub proc_macros: Vec<LocalDefId>,
139 /// Mapping from ident span to path span for paths that don't exist as written, but that
140 /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
141 pub confused_type_with_std_module: FxHashMap<Span, Span>,
144 #[derive(Clone, Copy, Debug)]
145 pub struct MainDefinition {
146 pub res: Res<ast::NodeId>,
151 impl MainDefinition {
152 pub fn opt_fn_def_id(self) -> Option<DefId> {
153 if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
157 /// The "header" of an impl is everything outside the body: a Self type, a trait
158 /// ref (in the case of a trait impl), and a set of predicates (from the
159 /// bounds / where-clauses).
160 #[derive(Clone, Debug, TypeFoldable)]
161 pub struct ImplHeader<'tcx> {
162 pub impl_def_id: DefId,
163 pub self_ty: Ty<'tcx>,
164 pub trait_ref: Option<TraitRef<'tcx>>,
165 pub predicates: Vec<Predicate<'tcx>>,
180 pub enum ImplPolarity {
181 /// `impl Trait for Type`
183 /// `impl !Trait for Type`
185 /// `#[rustc_reservation_impl] impl Trait for Type`
187 /// This is a "stability hack", not a real Rust feature.
188 /// See #64631 for details.
193 /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
194 pub fn flip(&self) -> Option<ImplPolarity> {
196 ImplPolarity::Positive => Some(ImplPolarity::Negative),
197 ImplPolarity::Negative => Some(ImplPolarity::Positive),
198 ImplPolarity::Reservation => None,
203 impl fmt::Display for ImplPolarity {
204 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
206 Self::Positive => f.write_str("positive"),
207 Self::Negative => f.write_str("negative"),
208 Self::Reservation => f.write_str("reservation"),
213 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
214 pub enum Visibility {
215 /// Visible everywhere (including in other crates).
217 /// Visible only in the given crate-local module.
219 /// Not visible anywhere in the local crate. This is the visibility of private external items.
223 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
224 pub enum BoundConstness {
227 /// `T: ~const Trait`
229 /// Requires resolving to const only when we are in a const context.
233 impl BoundConstness {
234 /// Reduce `self` and `constness` to two possible combined states instead of four.
235 pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
236 match (constness, self) {
237 (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
239 *this = BoundConstness::NotConst;
240 hir::Constness::NotConst
246 impl fmt::Display for BoundConstness {
247 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
249 Self::NotConst => f.write_str("normal"),
250 Self::ConstIfConst => f.write_str("`~const`"),
267 pub struct ClosureSizeProfileData<'tcx> {
268 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
269 pub before_feature_tys: Ty<'tcx>,
270 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
271 pub after_feature_tys: Ty<'tcx>,
274 pub trait DefIdTree: Copy {
275 fn parent(self, id: DefId) -> Option<DefId>;
277 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
278 if descendant.krate != ancestor.krate {
282 while descendant != ancestor {
283 match self.parent(descendant) {
284 Some(parent) => descendant = parent,
285 None => return false,
292 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
293 fn parent(self, id: DefId) -> Option<DefId> {
294 self.def_key(id).parent.map(|index| DefId { index, ..id })
299 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
300 match visibility.node {
301 hir::VisibilityKind::Public => Visibility::Public,
302 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
303 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
304 // If there is no resolution, `resolve` will have already reported an error, so
305 // assume that the visibility is public to avoid reporting more privacy errors.
306 Res::Err => Visibility::Public,
307 def => Visibility::Restricted(def.def_id()),
309 hir::VisibilityKind::Inherited => {
310 Visibility::Restricted(tcx.parent_module(id).to_def_id())
315 /// Returns `true` if an item with this visibility is accessible from the given block.
316 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
317 let restriction = match self {
318 // Public items are visible everywhere.
319 Visibility::Public => return true,
320 // Private items from other crates are visible nowhere.
321 Visibility::Invisible => return false,
322 // Restricted items are visible in an arbitrary local module.
323 Visibility::Restricted(other) if other.krate != module.krate => return false,
324 Visibility::Restricted(module) => module,
327 tree.is_descendant_of(module, restriction)
330 /// Returns `true` if this visibility is at least as accessible as the given visibility
331 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
332 let vis_restriction = match vis {
333 Visibility::Public => return self == Visibility::Public,
334 Visibility::Invisible => return true,
335 Visibility::Restricted(module) => module,
338 self.is_accessible_from(vis_restriction, tree)
341 // Returns `true` if this item is visible anywhere in the local crate.
342 pub fn is_visible_locally(self) -> bool {
344 Visibility::Public => true,
345 Visibility::Restricted(def_id) => def_id.is_local(),
346 Visibility::Invisible => false,
350 pub fn is_public(self) -> bool {
351 matches!(self, Visibility::Public)
355 /// The crate variances map is computed during typeck and contains the
356 /// variance of every item in the local crate. You should not use it
357 /// directly, because to do so will make your pass dependent on the
358 /// HIR of every item in the local crate. Instead, use
359 /// `tcx.variances_of()` to get the variance for a *particular*
361 #[derive(HashStable, Debug)]
362 pub struct CrateVariancesMap<'tcx> {
363 /// For each item with generics, maps to a vector of the variance
364 /// of its generics. If an item has no generics, it will have no
366 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
369 // Contains information needed to resolve types and (in the future) look up
370 // the types of AST nodes.
371 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
372 pub struct CReaderCacheKey {
373 pub cnum: Option<CrateNum>,
377 #[allow(rustc::usage_of_ty_tykind)]
378 pub struct TyS<'tcx> {
379 /// This field shouldn't be used directly and may be removed in the future.
380 /// Use `TyS::kind()` instead.
382 /// This field shouldn't be used directly and may be removed in the future.
383 /// Use `TyS::flags()` instead.
386 /// This is a kind of confusing thing: it stores the smallest
389 /// (a) the binder itself captures nothing but
390 /// (b) all the late-bound things within the type are captured
391 /// by some sub-binder.
393 /// So, for a type without any late-bound things, like `u32`, this
394 /// will be *innermost*, because that is the innermost binder that
395 /// captures nothing. But for a type `&'D u32`, where `'D` is a
396 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
397 /// -- the binder itself does not capture `D`, but `D` is captured
398 /// by an inner binder.
400 /// We call this concept an "exclusive" binder `D` because all
401 /// De Bruijn indices within the type are contained within `0..D`
403 outer_exclusive_binder: ty::DebruijnIndex,
406 impl<'tcx> TyS<'tcx> {
407 /// A constructor used only for internal testing.
408 #[allow(rustc::usage_of_ty_tykind)]
409 pub fn make_for_test(
412 outer_exclusive_binder: ty::DebruijnIndex,
414 TyS { kind, flags, outer_exclusive_binder }
418 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
419 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
420 static_assert_size!(TyS<'_>, 40);
422 impl<'tcx> Ord for TyS<'tcx> {
423 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
424 self.kind().cmp(other.kind())
428 impl<'tcx> PartialOrd for TyS<'tcx> {
429 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
430 Some(self.kind().cmp(other.kind()))
434 impl<'tcx> PartialEq for TyS<'tcx> {
436 fn eq(&self, other: &TyS<'tcx>) -> bool {
440 impl<'tcx> Eq for TyS<'tcx> {}
442 impl<'tcx> Hash for TyS<'tcx> {
443 fn hash<H: Hasher>(&self, s: &mut H) {
444 (self as *const TyS<'_>).hash(s)
448 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
449 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
453 // The other fields just provide fast access to information that is
454 // also contained in `kind`, so no need to hash them.
457 outer_exclusive_binder: _,
460 kind.hash_stable(hcx, hasher);
464 #[rustc_diagnostic_item = "Ty"]
465 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
467 impl ty::EarlyBoundRegion {
468 /// Does this early bound region have a name? Early bound regions normally
469 /// always have names except when using anonymous lifetimes (`'_`).
470 pub fn has_name(&self) -> bool {
471 self.name != kw::UnderscoreLifetime
476 crate struct PredicateInner<'tcx> {
477 kind: Binder<'tcx, PredicateKind<'tcx>>,
479 /// See the comment for the corresponding field of [TyS].
480 outer_exclusive_binder: ty::DebruijnIndex,
483 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
484 static_assert_size!(PredicateInner<'_>, 48);
486 #[derive(Clone, Copy, Lift)]
487 pub struct Predicate<'tcx> {
488 inner: &'tcx PredicateInner<'tcx>,
491 impl<'tcx> PartialEq for Predicate<'tcx> {
492 fn eq(&self, other: &Self) -> bool {
493 // `self.kind` is always interned.
494 ptr::eq(self.inner, other.inner)
498 impl Hash for Predicate<'_> {
499 fn hash<H: Hasher>(&self, s: &mut H) {
500 (self.inner as *const PredicateInner<'_>).hash(s)
504 impl<'tcx> Eq for Predicate<'tcx> {}
506 impl<'tcx> Predicate<'tcx> {
507 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
509 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
513 /// Flips the polarity of a Predicate.
515 /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
516 pub fn flip_polarity(&self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
520 .map_bound(|kind| match kind {
521 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
522 Some(PredicateKind::Trait(TraitPredicate {
525 polarity: polarity.flip()?,
533 Some(tcx.mk_predicate(kind))
537 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
538 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
542 // The other fields just provide fast access to information that is
543 // also contained in `kind`, so no need to hash them.
545 outer_exclusive_binder: _,
548 kind.hash_stable(hcx, hasher);
552 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
553 #[derive(HashStable, TypeFoldable)]
554 pub enum PredicateKind<'tcx> {
555 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
556 /// the `Self` type of the trait reference and `A`, `B`, and `C`
557 /// would be the type parameters.
558 Trait(TraitPredicate<'tcx>),
561 RegionOutlives(RegionOutlivesPredicate<'tcx>),
564 TypeOutlives(TypeOutlivesPredicate<'tcx>),
566 /// `where <T as TraitRef>::Name == X`, approximately.
567 /// See the `ProjectionPredicate` struct for details.
568 Projection(ProjectionPredicate<'tcx>),
570 /// No syntax: `T` well-formed.
571 WellFormed(GenericArg<'tcx>),
573 /// Trait must be object-safe.
576 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
577 /// for some substitutions `...` and `T` being a closure type.
578 /// Satisfied (or refuted) once we know the closure's kind.
579 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
583 /// This obligation is created most often when we have two
584 /// unresolved type variables and hence don't have enough
585 /// information to process the subtyping obligation yet.
586 Subtype(SubtypePredicate<'tcx>),
588 /// `T1` coerced to `T2`
590 /// Like a subtyping obligation, this is created most often
591 /// when we have two unresolved type variables and hence
592 /// don't have enough information to process the coercion
593 /// obligation yet. At the moment, we actually process coercions
594 /// very much like subtyping and don't handle the full coercion
596 Coerce(CoercePredicate<'tcx>),
598 /// Constant initializer must evaluate successfully.
599 ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
601 /// Constants must be equal. The first component is the const that is expected.
602 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
604 /// Represents a type found in the environment that we can use for implied bounds.
606 /// Only used for Chalk.
607 TypeWellFormedFromEnv(Ty<'tcx>),
610 /// The crate outlives map is computed during typeck and contains the
611 /// outlives of every item in the local crate. You should not use it
612 /// directly, because to do so will make your pass dependent on the
613 /// HIR of every item in the local crate. Instead, use
614 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
616 #[derive(HashStable, Debug)]
617 pub struct CratePredicatesMap<'tcx> {
618 /// For each struct with outlive bounds, maps to a vector of the
619 /// predicate of its outlive bounds. If an item has no outlives
620 /// bounds, it will have no entry.
621 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
624 impl<'tcx> Predicate<'tcx> {
625 /// Performs a substitution suitable for going from a
626 /// poly-trait-ref to supertraits that must hold if that
627 /// poly-trait-ref holds. This is slightly different from a normal
628 /// substitution in terms of what happens with bound regions. See
629 /// lengthy comment below for details.
630 pub fn subst_supertrait(
633 trait_ref: &ty::PolyTraitRef<'tcx>,
634 ) -> Predicate<'tcx> {
635 // The interaction between HRTB and supertraits is not entirely
636 // obvious. Let me walk you (and myself) through an example.
638 // Let's start with an easy case. Consider two traits:
640 // trait Foo<'a>: Bar<'a,'a> { }
641 // trait Bar<'b,'c> { }
643 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
644 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
645 // knew that `Foo<'x>` (for any 'x) then we also know that
646 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
647 // normal substitution.
649 // In terms of why this is sound, the idea is that whenever there
650 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
651 // holds. So if there is an impl of `T:Foo<'a>` that applies to
652 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
655 // Another example to be careful of is this:
657 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
658 // trait Bar1<'b,'c> { }
660 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
661 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
662 // reason is similar to the previous example: any impl of
663 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
664 // basically we would want to collapse the bound lifetimes from
665 // the input (`trait_ref`) and the supertraits.
667 // To achieve this in practice is fairly straightforward. Let's
668 // consider the more complicated scenario:
670 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
671 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
672 // where both `'x` and `'b` would have a DB index of 1.
673 // The substitution from the input trait-ref is therefore going to be
674 // `'a => 'x` (where `'x` has a DB index of 1).
675 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
676 // early-bound parameter and `'b' is a late-bound parameter with a
678 // - If we replace `'a` with `'x` from the input, it too will have
679 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
680 // just as we wanted.
682 // There is only one catch. If we just apply the substitution `'a
683 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
684 // adjust the DB index because we substituting into a binder (it
685 // tries to be so smart...) resulting in `for<'x> for<'b>
686 // Bar1<'x,'b>` (we have no syntax for this, so use your
687 // imagination). Basically the 'x will have DB index of 2 and 'b
688 // will have DB index of 1. Not quite what we want. So we apply
689 // the substitution to the *contents* of the trait reference,
690 // rather than the trait reference itself (put another way, the
691 // substitution code expects equal binding levels in the values
692 // from the substitution and the value being substituted into, and
693 // this trick achieves that).
695 // Working through the second example:
696 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
697 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
698 // We want to end up with:
699 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
701 // 1) We must shift all bound vars in predicate by the length
702 // of trait ref's bound vars. So, we would end up with predicate like
703 // Self: Bar1<'a, '^0.1>
704 // 2) We can then apply the trait substs to this, ending up with
705 // T: Bar1<'^0.0, '^0.1>
706 // 3) Finally, to create the final bound vars, we concatenate the bound
707 // vars of the trait ref with those of the predicate:
709 let bound_pred = self.kind();
710 let pred_bound_vars = bound_pred.bound_vars();
711 let trait_bound_vars = trait_ref.bound_vars();
712 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
714 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
715 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
716 let new = shifted_pred.subst(tcx, trait_ref.skip_binder().substs);
717 // 3) ['x] + ['b] -> ['x, 'b]
719 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
720 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
724 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
725 #[derive(HashStable, TypeFoldable)]
726 pub struct TraitPredicate<'tcx> {
727 pub trait_ref: TraitRef<'tcx>,
729 pub constness: BoundConstness,
731 pub polarity: ImplPolarity,
734 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
736 impl<'tcx> TraitPredicate<'tcx> {
737 pub fn remap_constness(&mut self, tcx: TyCtxt<'tcx>, param_env: &mut ParamEnv<'tcx>) {
738 if unlikely!(Some(self.trait_ref.def_id) == tcx.lang_items().drop_trait()) {
739 // remap without changing constness of this predicate.
740 // this is because `T: ~const Drop` has a different meaning to `T: Drop`
741 param_env.remap_constness_with(self.constness)
743 *param_env = param_env.with_constness(self.constness.and(param_env.constness()))
746 pub fn def_id(self) -> DefId {
747 self.trait_ref.def_id
750 pub fn self_ty(self) -> Ty<'tcx> {
751 self.trait_ref.self_ty()
755 impl<'tcx> PolyTraitPredicate<'tcx> {
756 pub fn def_id(self) -> DefId {
757 // Ok to skip binder since trait `DefId` does not care about regions.
758 self.skip_binder().def_id()
761 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
762 self.map_bound(|trait_ref| trait_ref.self_ty())
766 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
767 #[derive(HashStable, TypeFoldable)]
768 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
769 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
770 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
771 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
772 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
774 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
775 /// whether the `a` type is the type that we should label as "expected" when
776 /// presenting user diagnostics.
777 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
778 #[derive(HashStable, TypeFoldable)]
779 pub struct SubtypePredicate<'tcx> {
780 pub a_is_expected: bool,
784 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
786 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
787 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
788 #[derive(HashStable, TypeFoldable)]
789 pub struct CoercePredicate<'tcx> {
793 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
795 /// This kind of predicate has no *direct* correspondent in the
796 /// syntax, but it roughly corresponds to the syntactic forms:
798 /// 1. `T: TraitRef<..., Item = Type>`
799 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
801 /// In particular, form #1 is "desugared" to the combination of a
802 /// normal trait predicate (`T: TraitRef<...>`) and one of these
803 /// predicates. Form #2 is a broader form in that it also permits
804 /// equality between arbitrary types. Processing an instance of
805 /// Form #2 eventually yields one of these `ProjectionPredicate`
806 /// instances to normalize the LHS.
807 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
808 #[derive(HashStable, TypeFoldable)]
809 pub struct ProjectionPredicate<'tcx> {
810 pub projection_ty: ProjectionTy<'tcx>,
814 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
816 impl<'tcx> PolyProjectionPredicate<'tcx> {
817 /// Returns the `DefId` of the trait of the associated item being projected.
819 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
820 self.skip_binder().projection_ty.trait_def_id(tcx)
823 /// Get the [PolyTraitRef] required for this projection to be well formed.
824 /// Note that for generic associated types the predicates of the associated
825 /// type also need to be checked.
827 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
828 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
829 // `self.0.trait_ref` is permitted to have escaping regions.
830 // This is because here `self` has a `Binder` and so does our
831 // return value, so we are preserving the number of binding
833 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
836 pub fn ty(&self) -> Binder<'tcx, Ty<'tcx>> {
837 self.map_bound(|predicate| predicate.ty)
840 /// The `DefId` of the `TraitItem` for the associated type.
842 /// Note that this is not the `DefId` of the `TraitRef` containing this
843 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
844 pub fn projection_def_id(&self) -> DefId {
845 // Ok to skip binder since trait `DefId` does not care about regions.
846 self.skip_binder().projection_ty.item_def_id
850 pub trait ToPolyTraitRef<'tcx> {
851 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
854 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
855 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
856 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
860 pub trait ToPredicate<'tcx> {
861 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
864 impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
866 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
867 tcx.mk_predicate(self)
871 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
872 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
873 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
877 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
878 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
879 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
883 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
884 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
885 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
889 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
890 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
891 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
895 impl<'tcx> Predicate<'tcx> {
896 pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
897 let predicate = self.kind();
898 match predicate.skip_binder() {
899 PredicateKind::Trait(t) => Some(predicate.rebind(t)),
900 PredicateKind::Projection(..)
901 | PredicateKind::Subtype(..)
902 | PredicateKind::Coerce(..)
903 | PredicateKind::RegionOutlives(..)
904 | PredicateKind::WellFormed(..)
905 | PredicateKind::ObjectSafe(..)
906 | PredicateKind::ClosureKind(..)
907 | PredicateKind::TypeOutlives(..)
908 | PredicateKind::ConstEvaluatable(..)
909 | PredicateKind::ConstEquate(..)
910 | PredicateKind::TypeWellFormedFromEnv(..) => None,
914 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
915 let predicate = self.kind();
916 match predicate.skip_binder() {
917 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
918 PredicateKind::Trait(..)
919 | PredicateKind::Projection(..)
920 | PredicateKind::Subtype(..)
921 | PredicateKind::Coerce(..)
922 | PredicateKind::RegionOutlives(..)
923 | PredicateKind::WellFormed(..)
924 | PredicateKind::ObjectSafe(..)
925 | PredicateKind::ClosureKind(..)
926 | PredicateKind::ConstEvaluatable(..)
927 | PredicateKind::ConstEquate(..)
928 | PredicateKind::TypeWellFormedFromEnv(..) => None,
933 /// Represents the bounds declared on a particular set of type
934 /// parameters. Should eventually be generalized into a flag list of
935 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
936 /// `GenericPredicates` by using the `instantiate` method. Note that this method
937 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
938 /// the `GenericPredicates` are expressed in terms of the bound type
939 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
940 /// represented a set of bounds for some particular instantiation,
941 /// meaning that the generic parameters have been substituted with
946 /// struct Foo<T, U: Bar<T>> { ... }
948 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
949 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
950 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
951 /// [usize:Bar<isize>]]`.
952 #[derive(Clone, Debug, TypeFoldable)]
953 pub struct InstantiatedPredicates<'tcx> {
954 pub predicates: Vec<Predicate<'tcx>>,
955 pub spans: Vec<Span>,
958 impl<'tcx> InstantiatedPredicates<'tcx> {
959 pub fn empty() -> InstantiatedPredicates<'tcx> {
960 InstantiatedPredicates { predicates: vec![], spans: vec![] }
963 pub fn is_empty(&self) -> bool {
964 self.predicates.is_empty()
968 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable, TypeFoldable)]
969 pub struct OpaqueTypeKey<'tcx> {
971 pub substs: SubstsRef<'tcx>,
974 rustc_index::newtype_index! {
975 /// "Universes" are used during type- and trait-checking in the
976 /// presence of `for<..>` binders to control what sets of names are
977 /// visible. Universes are arranged into a tree: the root universe
978 /// contains names that are always visible. Each child then adds a new
979 /// set of names that are visible, in addition to those of its parent.
980 /// We say that the child universe "extends" the parent universe with
983 /// To make this more concrete, consider this program:
987 /// fn bar<T>(x: T) {
988 /// let y: for<'a> fn(&'a u8, Foo) = ...;
992 /// The struct name `Foo` is in the root universe U0. But the type
993 /// parameter `T`, introduced on `bar`, is in an extended universe U1
994 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
995 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
996 /// region `'a` is in a universe U2 that extends U1, because we can
997 /// name it inside the fn type but not outside.
999 /// Universes are used to do type- and trait-checking around these
1000 /// "forall" binders (also called **universal quantification**). The
1001 /// idea is that when, in the body of `bar`, we refer to `T` as a
1002 /// type, we aren't referring to any type in particular, but rather a
1003 /// kind of "fresh" type that is distinct from all other types we have
1004 /// actually declared. This is called a **placeholder** type, and we
1005 /// use universes to talk about this. In other words, a type name in
1006 /// universe 0 always corresponds to some "ground" type that the user
1007 /// declared, but a type name in a non-zero universe is a placeholder
1008 /// type -- an idealized representative of "types in general" that we
1009 /// use for checking generic functions.
1010 pub struct UniverseIndex {
1012 DEBUG_FORMAT = "U{}",
1016 impl UniverseIndex {
1017 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1019 /// Returns the "next" universe index in order -- this new index
1020 /// is considered to extend all previous universes. This
1021 /// corresponds to entering a `forall` quantifier. So, for
1022 /// example, suppose we have this type in universe `U`:
1025 /// for<'a> fn(&'a u32)
1028 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1029 /// new universe that extends `U` -- in this new universe, we can
1030 /// name the region `'a`, but that region was not nameable from
1031 /// `U` because it was not in scope there.
1032 pub fn next_universe(self) -> UniverseIndex {
1033 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1036 /// Returns `true` if `self` can name a name from `other` -- in other words,
1037 /// if the set of names in `self` is a superset of those in
1038 /// `other` (`self >= other`).
1039 pub fn can_name(self, other: UniverseIndex) -> bool {
1040 self.private >= other.private
1043 /// Returns `true` if `self` cannot name some names from `other` -- in other
1044 /// words, if the set of names in `self` is a strict subset of
1045 /// those in `other` (`self < other`).
1046 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1047 self.private < other.private
1051 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1052 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1053 /// regions/types/consts within the same universe simply have an unknown relationship to one
1055 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1056 pub struct Placeholder<T> {
1057 pub universe: UniverseIndex,
1061 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1063 T: HashStable<StableHashingContext<'a>>,
1065 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1066 self.universe.hash_stable(hcx, hasher);
1067 self.name.hash_stable(hcx, hasher);
1071 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1073 pub type PlaceholderType = Placeholder<BoundVar>;
1075 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1076 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1077 pub struct BoundConst<'tcx> {
1082 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1084 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1085 /// the `DefId` of the generic parameter it instantiates.
1087 /// This is used to avoid calls to `type_of` for const arguments during typeck
1088 /// which cause cycle errors.
1093 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1094 /// // ^ const parameter
1098 /// fn foo<const M: u8>(&self) -> usize { 42 }
1099 /// // ^ const parameter
1104 /// let _b = a.foo::<{ 3 + 7 }>();
1105 /// // ^^^^^^^^^ const argument
1109 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1110 /// which `foo` is used until we know the type of `a`.
1112 /// We only know the type of `a` once we are inside of `typeck(main)`.
1113 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1114 /// requires us to evaluate the const argument.
1116 /// To evaluate that const argument we need to know its type,
1117 /// which we would get using `type_of(const_arg)`. This requires us to
1118 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1119 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1120 /// which results in a cycle.
1122 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1124 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1125 /// already resolved `foo` so we know which const parameter this argument instantiates.
1126 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1127 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1128 /// trivial to compute.
1130 /// If we now want to use that constant in a place which potentionally needs its type
1131 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1132 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1133 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1134 /// to get the type of `did`.
1135 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1136 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1137 #[derive(Hash, HashStable)]
1138 pub struct WithOptConstParam<T> {
1140 /// The `DefId` of the corresponding generic parameter in case `did` is
1141 /// a const argument.
1143 /// Note that even if `did` is a const argument, this may still be `None`.
1144 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1145 /// to potentially update `param_did` in the case it is `None`.
1146 pub const_param_did: Option<DefId>,
1149 impl<T> WithOptConstParam<T> {
1150 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1152 pub fn unknown(did: T) -> WithOptConstParam<T> {
1153 WithOptConstParam { did, const_param_did: None }
1157 impl WithOptConstParam<LocalDefId> {
1158 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1159 /// `None` otherwise.
1161 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1162 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1165 /// In case `self` is unknown but `self.did` is a const argument, this returns
1166 /// a `WithOptConstParam` with the correct `const_param_did`.
1168 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1169 if self.const_param_did.is_none() {
1170 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1171 return Some(WithOptConstParam { did: self.did, const_param_did });
1178 pub fn to_global(self) -> WithOptConstParam<DefId> {
1179 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1182 pub fn def_id_for_type_of(self) -> DefId {
1183 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1187 impl WithOptConstParam<DefId> {
1188 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1191 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1194 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1195 if let Some(param_did) = self.const_param_did {
1196 if let Some(did) = self.did.as_local() {
1197 return Some((did, param_did));
1204 pub fn is_local(self) -> bool {
1208 pub fn def_id_for_type_of(self) -> DefId {
1209 self.const_param_did.unwrap_or(self.did)
1213 /// When type checking, we use the `ParamEnv` to track
1214 /// details about the set of where-clauses that are in scope at this
1215 /// particular point.
1216 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1217 pub struct ParamEnv<'tcx> {
1218 /// This packs both caller bounds and the reveal enum into one pointer.
1220 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1221 /// basically the set of bounds on the in-scope type parameters, translated
1222 /// into `Obligation`s, and elaborated and normalized.
1224 /// Use the `caller_bounds()` method to access.
1226 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1227 /// want `Reveal::All`.
1229 /// Note: This is packed, use the reveal() method to access it.
1230 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
1233 #[derive(Copy, Clone)]
1235 reveal: traits::Reveal,
1236 constness: hir::Constness,
1239 unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
1240 const BITS: usize = 2;
1242 fn into_usize(self) -> usize {
1244 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
1245 Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
1246 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
1247 Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
1251 unsafe fn from_usize(ptr: usize) -> Self {
1253 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1254 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
1255 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
1256 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
1257 _ => std::hint::unreachable_unchecked(),
1262 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1263 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1264 f.debug_struct("ParamEnv")
1265 .field("caller_bounds", &self.caller_bounds())
1266 .field("reveal", &self.reveal())
1267 .field("constness", &self.constness())
1272 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1273 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1274 self.caller_bounds().hash_stable(hcx, hasher);
1275 self.reveal().hash_stable(hcx, hasher);
1276 self.constness().hash_stable(hcx, hasher);
1280 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1281 fn try_super_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
1284 ) -> Result<Self, F::Error> {
1286 self.caller_bounds().try_fold_with(folder)?,
1287 self.reveal().try_fold_with(folder)?,
1288 self.constness().try_fold_with(folder)?,
1292 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1293 self.caller_bounds().visit_with(visitor)?;
1294 self.reveal().visit_with(visitor)?;
1295 self.constness().visit_with(visitor)
1299 impl<'tcx> ParamEnv<'tcx> {
1300 /// Construct a trait environment suitable for contexts where
1301 /// there are no where-clauses in scope. Hidden types (like `impl
1302 /// Trait`) are left hidden, so this is suitable for ordinary
1305 pub fn empty() -> Self {
1306 Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
1310 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1311 self.packed.pointer()
1315 pub fn reveal(self) -> traits::Reveal {
1316 self.packed.tag().reveal
1320 pub fn constness(self) -> hir::Constness {
1321 self.packed.tag().constness
1324 /// Construct a trait environment with no where-clauses in scope
1325 /// where the values of all `impl Trait` and other hidden types
1326 /// are revealed. This is suitable for monomorphized, post-typeck
1327 /// environments like codegen or doing optimizations.
1329 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1330 /// or invoke `param_env.with_reveal_all()`.
1332 pub fn reveal_all() -> Self {
1333 Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
1336 /// Construct a trait environment with the given set of predicates.
1339 caller_bounds: &'tcx List<Predicate<'tcx>>,
1341 constness: hir::Constness,
1343 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
1346 pub fn with_user_facing(mut self) -> Self {
1347 self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
1352 pub fn with_constness(mut self, constness: hir::Constness) -> Self {
1353 self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
1358 pub fn with_const(mut self) -> Self {
1359 self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
1364 pub fn without_const(mut self) -> Self {
1365 self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
1370 pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
1371 *self = self.with_constness(constness.and(self.constness()))
1374 /// Returns a new parameter environment with the same clauses, but
1375 /// which "reveals" the true results of projections in all cases
1376 /// (even for associated types that are specializable). This is
1377 /// the desired behavior during codegen and certain other special
1378 /// contexts; normally though we want to use `Reveal::UserFacing`,
1379 /// which is the default.
1380 /// All opaque types in the caller_bounds of the `ParamEnv`
1381 /// will be normalized to their underlying types.
1382 /// See PR #65989 and issue #65918 for more details
1383 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1384 if self.packed.tag().reveal == traits::Reveal::All {
1389 tcx.normalize_opaque_types(self.caller_bounds()),
1395 /// Returns this same environment but with no caller bounds.
1397 pub fn without_caller_bounds(self) -> Self {
1398 Self::new(List::empty(), self.reveal(), self.constness())
1401 /// Creates a suitable environment in which to perform trait
1402 /// queries on the given value. When type-checking, this is simply
1403 /// the pair of the environment plus value. But when reveal is set to
1404 /// All, then if `value` does not reference any type parameters, we will
1405 /// pair it with the empty environment. This improves caching and is generally
1408 /// N.B., we preserve the environment when type-checking because it
1409 /// is possible for the user to have wacky where-clauses like
1410 /// `where Box<u32>: Copy`, which are clearly never
1411 /// satisfiable. We generally want to behave as if they were true,
1412 /// although the surrounding function is never reachable.
1413 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1414 match self.reveal() {
1415 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1418 if value.is_known_global() {
1419 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1421 ParamEnvAnd { param_env: self, value }
1428 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1429 // the constness of trait bounds is being propagated correctly.
1430 impl<'tcx> PolyTraitRef<'tcx> {
1432 pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
1433 self.map_bound(|trait_ref| ty::TraitPredicate {
1436 polarity: ty::ImplPolarity::Positive,
1440 pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
1441 self.with_constness(BoundConstness::NotConst)
1445 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1446 pub struct ParamEnvAnd<'tcx, T> {
1447 pub param_env: ParamEnv<'tcx>,
1451 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1452 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1453 (self.param_env, self.value)
1457 pub fn without_const(mut self) -> Self {
1458 self.param_env = self.param_env.without_const();
1463 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1465 T: HashStable<StableHashingContext<'a>>,
1467 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1468 let ParamEnvAnd { ref param_env, ref value } = *self;
1470 param_env.hash_stable(hcx, hasher);
1471 value.hash_stable(hcx, hasher);
1475 #[derive(Copy, Clone, Debug, HashStable)]
1476 pub struct Destructor {
1477 /// The `DefId` of the destructor method
1479 /// The constness of the destructor method
1480 pub constness: hir::Constness,
1484 #[derive(HashStable, TyEncodable, TyDecodable)]
1485 pub struct VariantFlags: u32 {
1486 const NO_VARIANT_FLAGS = 0;
1487 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1488 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1489 /// Indicates whether this variant was obtained as part of recovering from
1490 /// a syntactic error. May be incomplete or bogus.
1491 const IS_RECOVERED = 1 << 1;
1495 /// Definition of a variant -- a struct's fields or an enum variant.
1496 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1497 pub struct VariantDef {
1498 /// `DefId` that identifies the variant itself.
1499 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1501 /// `DefId` that identifies the variant's constructor.
1502 /// If this variant is a struct variant, then this is `None`.
1503 pub ctor_def_id: Option<DefId>,
1504 /// Variant or struct name.
1505 #[stable_hasher(project(name))]
1507 /// Discriminant of this variant.
1508 pub discr: VariantDiscr,
1509 /// Fields of this variant.
1510 pub fields: Vec<FieldDef>,
1511 /// Type of constructor of variant.
1512 pub ctor_kind: CtorKind,
1513 /// Flags of the variant (e.g. is field list non-exhaustive)?
1514 flags: VariantFlags,
1518 /// Creates a new `VariantDef`.
1520 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1521 /// represents an enum variant).
1523 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1524 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1526 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1527 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1528 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1529 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1530 /// built-in trait), and we do not want to load attributes twice.
1532 /// If someone speeds up attribute loading to not be a performance concern, they can
1533 /// remove this hack and use the constructor `DefId` everywhere.
1536 variant_did: Option<DefId>,
1537 ctor_def_id: Option<DefId>,
1538 discr: VariantDiscr,
1539 fields: Vec<FieldDef>,
1540 ctor_kind: CtorKind,
1544 is_field_list_non_exhaustive: bool,
1547 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1548 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1549 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1552 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1553 if is_field_list_non_exhaustive {
1554 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1558 flags |= VariantFlags::IS_RECOVERED;
1562 def_id: variant_did.unwrap_or(parent_did),
1572 /// Is this field list non-exhaustive?
1574 pub fn is_field_list_non_exhaustive(&self) -> bool {
1575 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1578 /// Was this variant obtained as part of recovering from a syntactic error?
1580 pub fn is_recovered(&self) -> bool {
1581 self.flags.intersects(VariantFlags::IS_RECOVERED)
1585 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1586 pub enum VariantDiscr {
1587 /// Explicit value for this variant, i.e., `X = 123`.
1588 /// The `DefId` corresponds to the embedded constant.
1591 /// The previous variant's discriminant plus one.
1592 /// For efficiency reasons, the distance from the
1593 /// last `Explicit` discriminant is being stored,
1594 /// or `0` for the first variant, if it has none.
1598 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1599 pub struct FieldDef {
1601 #[stable_hasher(project(name))]
1603 pub vis: Visibility,
1607 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1608 pub struct ReprFlags: u8 {
1609 const IS_C = 1 << 0;
1610 const IS_SIMD = 1 << 1;
1611 const IS_TRANSPARENT = 1 << 2;
1612 // Internal only for now. If true, don't reorder fields.
1613 const IS_LINEAR = 1 << 3;
1614 // If true, don't expose any niche to type's context.
1615 const HIDE_NICHE = 1 << 4;
1616 // If true, the type's layout can be randomized using
1617 // the seed stored in `ReprOptions.layout_seed`
1618 const RANDOMIZE_LAYOUT = 1 << 5;
1619 // Any of these flags being set prevent field reordering optimisation.
1620 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
1621 | ReprFlags::IS_SIMD.bits
1622 | ReprFlags::IS_LINEAR.bits;
1626 /// Represents the repr options provided by the user,
1627 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
1628 pub struct ReprOptions {
1629 pub int: Option<attr::IntType>,
1630 pub align: Option<Align>,
1631 pub pack: Option<Align>,
1632 pub flags: ReprFlags,
1633 /// The seed to be used for randomizing a type's layout
1635 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
1636 /// be the "most accurate" hash as it'd encompass the item and crate
1637 /// hash without loss, but it does pay the price of being larger.
1638 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
1639 /// purposes (primarily `-Z randomize-layout`)
1640 pub field_shuffle_seed: u64,
1644 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1645 let mut flags = ReprFlags::empty();
1646 let mut size = None;
1647 let mut max_align: Option<Align> = None;
1648 let mut min_pack: Option<Align> = None;
1650 // Generate a deterministically-derived seed from the item's path hash
1651 // to allow for cross-crate compilation to actually work
1652 let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
1654 // If the user defined a custom seed for layout randomization, xor the item's
1655 // path hash with the user defined seed, this will allowing determinism while
1656 // still allowing users to further randomize layout generation for e.g. fuzzing
1657 if let Some(user_seed) = tcx.sess.opts.debugging_opts.layout_seed {
1658 field_shuffle_seed ^= user_seed;
1661 for attr in tcx.get_attrs(did).iter() {
1662 for r in attr::find_repr_attrs(&tcx.sess, attr) {
1663 flags.insert(match r {
1664 attr::ReprC => ReprFlags::IS_C,
1665 attr::ReprPacked(pack) => {
1666 let pack = Align::from_bytes(pack as u64).unwrap();
1667 min_pack = Some(if let Some(min_pack) = min_pack {
1674 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1675 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
1676 attr::ReprSimd => ReprFlags::IS_SIMD,
1677 attr::ReprInt(i) => {
1681 attr::ReprAlign(align) => {
1682 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
1689 // If `-Z randomize-layout` was enabled for the type definition then we can
1690 // consider performing layout randomization
1691 if tcx.sess.opts.debugging_opts.randomize_layout {
1692 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1695 // This is here instead of layout because the choice must make it into metadata.
1696 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
1697 flags.insert(ReprFlags::IS_LINEAR);
1700 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1704 pub fn simd(&self) -> bool {
1705 self.flags.contains(ReprFlags::IS_SIMD)
1709 pub fn c(&self) -> bool {
1710 self.flags.contains(ReprFlags::IS_C)
1714 pub fn packed(&self) -> bool {
1719 pub fn transparent(&self) -> bool {
1720 self.flags.contains(ReprFlags::IS_TRANSPARENT)
1724 pub fn linear(&self) -> bool {
1725 self.flags.contains(ReprFlags::IS_LINEAR)
1729 pub fn hide_niche(&self) -> bool {
1730 self.flags.contains(ReprFlags::HIDE_NICHE)
1733 /// Returns the discriminant type, given these `repr` options.
1734 /// This must only be called on enums!
1735 pub fn discr_type(&self) -> attr::IntType {
1736 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1739 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
1740 /// layout" optimizations, such as representing `Foo<&T>` as a
1742 pub fn inhibit_enum_layout_opt(&self) -> bool {
1743 self.c() || self.int.is_some()
1746 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
1747 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
1748 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
1749 if let Some(pack) = self.pack {
1750 if pack.bytes() == 1 {
1755 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
1758 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
1759 /// was enabled for its declaration crate
1760 pub fn can_randomize_type_layout(&self) -> bool {
1761 !self.inhibit_struct_field_reordering_opt()
1762 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
1765 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
1766 pub fn inhibit_union_abi_opt(&self) -> bool {
1771 impl<'tcx> FieldDef {
1772 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
1773 /// typically obtained via the second field of [`TyKind::Adt`].
1774 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
1775 tcx.type_of(self.did).subst(tcx, subst)
1779 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
1781 #[derive(Debug, PartialEq, Eq)]
1782 pub enum ImplOverlapKind {
1783 /// These impls are always allowed to overlap.
1785 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1788 /// These impls are allowed to overlap, but that raises
1789 /// an issue #33140 future-compatibility warning.
1791 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
1792 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
1794 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
1795 /// that difference, making what reduces to the following set of impls:
1799 /// impl Trait for dyn Send + Sync {}
1800 /// impl Trait for dyn Sync + Send {}
1803 /// Obviously, once we made these types be identical, that code causes a coherence
1804 /// error and a fairly big headache for us. However, luckily for us, the trait
1805 /// `Trait` used in this case is basically a marker trait, and therefore having
1806 /// overlapping impls for it is sound.
1808 /// To handle this, we basically regard the trait as a marker trait, with an additional
1809 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
1810 /// it has the following restrictions:
1812 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
1814 /// 2. The trait-ref of both impls must be equal.
1815 /// 3. The trait-ref of both impls must be a trait object type consisting only of
1817 /// 4. Neither of the impls can have any where-clauses.
1819 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
1823 impl<'tcx> TyCtxt<'tcx> {
1824 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1825 self.typeck(self.hir().body_owner_def_id(body))
1828 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1829 self.associated_items(id)
1830 .in_definition_order()
1831 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
1834 fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
1835 self.hir().get_if_local(def_id).and_then(|node| node.ident())
1838 fn item_name_from_def_id(self, def_id: DefId) -> Option<Symbol> {
1839 if def_id.index == CRATE_DEF_INDEX {
1840 Some(self.crate_name(def_id.krate))
1842 let def_key = self.def_key(def_id);
1843 match def_key.disambiguated_data.data {
1844 // The name of a constructor is that of its parent.
1845 rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId {
1846 krate: def_id.krate,
1847 index: def_key.parent.unwrap(),
1849 _ => def_key.disambiguated_data.data.get_opt_name(),
1854 /// Look up the name of an item across crates. This does not look at HIR.
1856 /// When possible, this function should be used for cross-crate lookups over
1857 /// [`opt_item_name`] to avoid invalidating the incremental cache. If you
1858 /// need to handle items without a name, or HIR items that will not be
1859 /// serialized cross-crate, or if you need the span of the item, use
1860 /// [`opt_item_name`] instead.
1862 /// [`opt_item_name`]: Self::opt_item_name
1863 pub fn item_name(self, id: DefId) -> Symbol {
1864 // Look at cross-crate items first to avoid invalidating the incremental cache
1865 // unless we have to.
1866 self.item_name_from_def_id(id).unwrap_or_else(|| {
1867 bug!("item_name: no name for {:?}", self.def_path(id));
1871 /// Look up the name and span of an item or [`Node`].
1873 /// See [`item_name`][Self::item_name] for more information.
1874 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
1875 // Look at the HIR first so the span will be correct if this is a local item.
1876 self.item_name_from_hir(def_id)
1877 .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span))
1880 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
1881 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
1882 Some(self.associated_item(def_id))
1888 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
1889 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
1892 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
1893 variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id))
1896 /// Returns `true` if the impls are the same polarity and the trait either
1897 /// has no items or is annotated `#[marker]` and prevents item overrides.
1898 pub fn impls_are_allowed_to_overlap(
1902 ) -> Option<ImplOverlapKind> {
1903 // If either trait impl references an error, they're allowed to overlap,
1904 // as one of them essentially doesn't exist.
1905 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
1906 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
1908 return Some(ImplOverlapKind::Permitted { marker: false });
1911 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
1912 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
1913 // `#[rustc_reservation_impl]` impls don't overlap with anything
1915 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
1918 return Some(ImplOverlapKind::Permitted { marker: false });
1920 (ImplPolarity::Positive, ImplPolarity::Negative)
1921 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
1922 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
1924 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
1929 (ImplPolarity::Positive, ImplPolarity::Positive)
1930 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
1933 let is_marker_overlap = {
1934 let is_marker_impl = |def_id: DefId| -> bool {
1935 let trait_ref = self.impl_trait_ref(def_id);
1936 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
1938 is_marker_impl(def_id1) && is_marker_impl(def_id2)
1941 if is_marker_overlap {
1943 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
1946 Some(ImplOverlapKind::Permitted { marker: true })
1948 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
1949 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
1950 if self_ty1 == self_ty2 {
1952 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
1955 return Some(ImplOverlapKind::Issue33140);
1958 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
1959 def_id1, def_id2, self_ty1, self_ty2
1965 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
1970 /// Returns `ty::VariantDef` if `res` refers to a struct,
1971 /// or variant or their constructors, panics otherwise.
1972 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
1974 Res::Def(DefKind::Variant, did) => {
1975 let enum_did = self.parent(did).unwrap();
1976 self.adt_def(enum_did).variant_with_id(did)
1978 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
1979 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
1980 let variant_did = self.parent(variant_ctor_did).unwrap();
1981 let enum_did = self.parent(variant_did).unwrap();
1982 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
1984 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
1985 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
1986 self.adt_def(struct_did).non_enum_variant()
1988 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
1992 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
1993 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
1995 ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
1998 | DefKind::AssocConst
2000 | DefKind::AnonConst
2001 | DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
2002 // If the caller wants `mir_for_ctfe` of a function they should not be using
2003 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2005 assert_eq!(def.const_param_did, None);
2006 self.optimized_mir(def.did)
2009 ty::InstanceDef::VtableShim(..)
2010 | ty::InstanceDef::ReifyShim(..)
2011 | ty::InstanceDef::Intrinsic(..)
2012 | ty::InstanceDef::FnPtrShim(..)
2013 | ty::InstanceDef::Virtual(..)
2014 | ty::InstanceDef::ClosureOnceShim { .. }
2015 | ty::InstanceDef::DropGlue(..)
2016 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2020 /// Gets the attributes of a definition.
2021 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
2022 if let Some(did) = did.as_local() {
2023 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2025 self.item_attrs(did)
2029 /// Determines whether an item is annotated with an attribute.
2030 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2031 self.sess.contains_name(&self.get_attrs(did), attr)
2034 /// Determines whether an item is annotated with `doc(hidden)`.
2035 pub fn is_doc_hidden(self, did: DefId) -> bool {
2038 .filter_map(|attr| if attr.has_name(sym::doc) { attr.meta_item_list() } else { None })
2039 .any(|items| items.iter().any(|item| item.has_name(sym::hidden)))
2042 /// Returns `true` if this is an `auto trait`.
2043 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2044 self.trait_def(trait_def_id).has_auto_impl
2047 /// Returns layout of a generator. Layout might be unavailable if the
2048 /// generator is tainted by errors.
2049 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2050 self.optimized_mir(def_id).generator_layout()
2053 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2054 /// If it implements no trait, returns `None`.
2055 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2056 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2059 /// If the given defid describes a method belonging to an impl, returns the
2060 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2061 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2062 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
2063 TraitContainer(_) => None,
2064 ImplContainer(def_id) => Some(def_id),
2068 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2069 /// with the name of the crate containing the impl.
2070 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2071 if let Some(impl_did) = impl_did.as_local() {
2072 let hir_id = self.hir().local_def_id_to_hir_id(impl_did);
2073 Ok(self.hir().span(hir_id))
2075 Err(self.crate_name(impl_did.krate))
2079 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2080 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2081 /// definition's parent/scope to perform comparison.
2082 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2083 // We could use `Ident::eq` here, but we deliberately don't. The name
2084 // comparison fails frequently, and we want to avoid the expensive
2085 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2086 use_name.name == def_name.name
2090 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2093 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2094 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2098 pub fn adjust_ident_and_get_scope(
2103 ) -> (Ident, DefId) {
2106 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2107 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2108 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2112 pub fn is_object_safe(self, key: DefId) -> bool {
2113 self.object_safety_violations(key).is_empty()
2117 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
2118 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
2119 let def_id = def_id.as_local()?;
2120 if let Node::Item(item) = tcx.hir().get(tcx.hir().local_def_id_to_hir_id(def_id)) {
2121 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2122 return match opaque_ty.origin {
2123 hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
2126 hir::OpaqueTyOrigin::TyAlias => None,
2133 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2135 ast::IntTy::Isize => IntTy::Isize,
2136 ast::IntTy::I8 => IntTy::I8,
2137 ast::IntTy::I16 => IntTy::I16,
2138 ast::IntTy::I32 => IntTy::I32,
2139 ast::IntTy::I64 => IntTy::I64,
2140 ast::IntTy::I128 => IntTy::I128,
2144 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2146 ast::UintTy::Usize => UintTy::Usize,
2147 ast::UintTy::U8 => UintTy::U8,
2148 ast::UintTy::U16 => UintTy::U16,
2149 ast::UintTy::U32 => UintTy::U32,
2150 ast::UintTy::U64 => UintTy::U64,
2151 ast::UintTy::U128 => UintTy::U128,
2155 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2157 ast::FloatTy::F32 => FloatTy::F32,
2158 ast::FloatTy::F64 => FloatTy::F64,
2162 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2164 IntTy::Isize => ast::IntTy::Isize,
2165 IntTy::I8 => ast::IntTy::I8,
2166 IntTy::I16 => ast::IntTy::I16,
2167 IntTy::I32 => ast::IntTy::I32,
2168 IntTy::I64 => ast::IntTy::I64,
2169 IntTy::I128 => ast::IntTy::I128,
2173 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2175 UintTy::Usize => ast::UintTy::Usize,
2176 UintTy::U8 => ast::UintTy::U8,
2177 UintTy::U16 => ast::UintTy::U16,
2178 UintTy::U32 => ast::UintTy::U32,
2179 UintTy::U64 => ast::UintTy::U64,
2180 UintTy::U128 => ast::UintTy::U128,
2184 pub fn provide(providers: &mut ty::query::Providers) {
2185 closure::provide(providers);
2186 context::provide(providers);
2187 erase_regions::provide(providers);
2188 layout::provide(providers);
2189 util::provide(providers);
2190 print::provide(providers);
2191 super::util::bug::provide(providers);
2192 super::middle::provide(providers);
2193 *providers = ty::query::Providers {
2194 trait_impls_of: trait_def::trait_impls_of_provider,
2195 type_uninhabited_from: inhabitedness::type_uninhabited_from,
2196 const_param_default: consts::const_param_default,
2197 vtable_allocation: vtable::vtable_allocation_provider,
2202 /// A map for the local crate mapping each type to a vector of its
2203 /// inherent impls. This is not meant to be used outside of coherence;
2204 /// rather, you should request the vector for a specific type via
2205 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2206 /// (constructing this map requires touching the entire crate).
2207 #[derive(Clone, Debug, Default, HashStable)]
2208 pub struct CrateInherentImpls {
2209 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2212 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2213 pub struct SymbolName<'tcx> {
2214 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2215 pub name: &'tcx str,
2218 impl<'tcx> SymbolName<'tcx> {
2219 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2221 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2226 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2227 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2228 fmt::Display::fmt(&self.name, fmt)
2232 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2233 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2234 fmt::Display::fmt(&self.name, fmt)
2238 #[derive(Debug, Default, Copy, Clone)]
2239 pub struct FoundRelationships {
2240 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2241 /// obligation, where:
2243 /// * `Foo` is not `Sized`
2244 /// * `(): Foo` may be satisfied
2245 pub self_in_trait: bool,
2246 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2247 /// _>::AssocType = ?T`