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::{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::hir::exports::ExportMap;
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, ParamConst, ParamTy, PolyExistentialProjection,
78 PolyExistentialTraitRef, PolyFnSig, PolyGenSig, PolyTraitRef, ProjectionTy, Region, RegionKind,
79 RegionVid, TraitRef, TyKind, TypeAndMut, UpvarSubsts, VarianceDiagInfo, VarianceDiagMutKind,
81 pub use self::trait_def::TraitDef;
92 pub mod inhabitedness;
94 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 export_map: ExportMap,
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 pub fn flip(&self) -> Option<ImplPolarity> {
195 ImplPolarity::Positive => Some(ImplPolarity::Negative),
196 ImplPolarity::Negative => Some(ImplPolarity::Positive),
197 ImplPolarity::Reservation => None,
202 impl fmt::Display for ImplPolarity {
203 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
205 Self::Positive => f.write_str("positive"),
206 Self::Negative => f.write_str("negative"),
207 Self::Reservation => f.write_str("reservation"),
212 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
213 pub enum Visibility {
214 /// Visible everywhere (including in other crates).
216 /// Visible only in the given crate-local module.
218 /// Not visible anywhere in the local crate. This is the visibility of private external items.
222 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
223 pub enum BoundConstness {
226 /// `T: ~const Trait`
228 /// Requires resolving to const only when we are in a const context.
232 impl fmt::Display for BoundConstness {
233 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
235 Self::NotConst => f.write_str("normal"),
236 Self::ConstIfConst => f.write_str("`~const`"),
253 pub struct ClosureSizeProfileData<'tcx> {
254 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
255 pub before_feature_tys: Ty<'tcx>,
256 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
257 pub after_feature_tys: Ty<'tcx>,
260 pub trait DefIdTree: Copy {
261 fn parent(self, id: DefId) -> Option<DefId>;
263 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
264 if descendant.krate != ancestor.krate {
268 while descendant != ancestor {
269 match self.parent(descendant) {
270 Some(parent) => descendant = parent,
271 None => return false,
278 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
279 fn parent(self, id: DefId) -> Option<DefId> {
280 self.def_key(id).parent.map(|index| DefId { index, ..id })
285 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
286 match visibility.node {
287 hir::VisibilityKind::Public => Visibility::Public,
288 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
289 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
290 // If there is no resolution, `resolve` will have already reported an error, so
291 // assume that the visibility is public to avoid reporting more privacy errors.
292 Res::Err => Visibility::Public,
293 def => Visibility::Restricted(def.def_id()),
295 hir::VisibilityKind::Inherited => {
296 Visibility::Restricted(tcx.parent_module(id).to_def_id())
301 /// Returns `true` if an item with this visibility is accessible from the given block.
302 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
303 let restriction = match self {
304 // Public items are visible everywhere.
305 Visibility::Public => return true,
306 // Private items from other crates are visible nowhere.
307 Visibility::Invisible => return false,
308 // Restricted items are visible in an arbitrary local module.
309 Visibility::Restricted(other) if other.krate != module.krate => return false,
310 Visibility::Restricted(module) => module,
313 tree.is_descendant_of(module, restriction)
316 /// Returns `true` if this visibility is at least as accessible as the given visibility
317 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
318 let vis_restriction = match vis {
319 Visibility::Public => return self == Visibility::Public,
320 Visibility::Invisible => return true,
321 Visibility::Restricted(module) => module,
324 self.is_accessible_from(vis_restriction, tree)
327 // Returns `true` if this item is visible anywhere in the local crate.
328 pub fn is_visible_locally(self) -> bool {
330 Visibility::Public => true,
331 Visibility::Restricted(def_id) => def_id.is_local(),
332 Visibility::Invisible => false,
337 /// The crate variances map is computed during typeck and contains the
338 /// variance of every item in the local crate. You should not use it
339 /// directly, because to do so will make your pass dependent on the
340 /// HIR of every item in the local crate. Instead, use
341 /// `tcx.variances_of()` to get the variance for a *particular*
343 #[derive(HashStable, Debug)]
344 pub struct CrateVariancesMap<'tcx> {
345 /// For each item with generics, maps to a vector of the variance
346 /// of its generics. If an item has no generics, it will have no
348 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
351 // Contains information needed to resolve types and (in the future) look up
352 // the types of AST nodes.
353 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
354 pub struct CReaderCacheKey {
355 pub cnum: Option<CrateNum>,
359 #[allow(rustc::usage_of_ty_tykind)]
360 pub struct TyS<'tcx> {
361 /// This field shouldn't be used directly and may be removed in the future.
362 /// Use `TyS::kind()` instead.
364 /// This field shouldn't be used directly and may be removed in the future.
365 /// Use `TyS::flags()` instead.
368 /// This is a kind of confusing thing: it stores the smallest
371 /// (a) the binder itself captures nothing but
372 /// (b) all the late-bound things within the type are captured
373 /// by some sub-binder.
375 /// So, for a type without any late-bound things, like `u32`, this
376 /// will be *innermost*, because that is the innermost binder that
377 /// captures nothing. But for a type `&'D u32`, where `'D` is a
378 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
379 /// -- the binder itself does not capture `D`, but `D` is captured
380 /// by an inner binder.
382 /// We call this concept an "exclusive" binder `D` because all
383 /// De Bruijn indices within the type are contained within `0..D`
385 outer_exclusive_binder: ty::DebruijnIndex,
388 impl<'tcx> TyS<'tcx> {
389 /// A constructor used only for internal testing.
390 #[allow(rustc::usage_of_ty_tykind)]
391 pub fn make_for_test(
394 outer_exclusive_binder: ty::DebruijnIndex,
396 TyS { kind, flags, outer_exclusive_binder }
400 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
401 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
402 static_assert_size!(TyS<'_>, 40);
404 impl<'tcx> Ord for TyS<'tcx> {
405 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
406 self.kind().cmp(other.kind())
410 impl<'tcx> PartialOrd for TyS<'tcx> {
411 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
412 Some(self.kind().cmp(other.kind()))
416 impl<'tcx> PartialEq for TyS<'tcx> {
418 fn eq(&self, other: &TyS<'tcx>) -> bool {
422 impl<'tcx> Eq for TyS<'tcx> {}
424 impl<'tcx> Hash for TyS<'tcx> {
425 fn hash<H: Hasher>(&self, s: &mut H) {
426 (self as *const TyS<'_>).hash(s)
430 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
431 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
435 // The other fields just provide fast access to information that is
436 // also contained in `kind`, so no need to hash them.
439 outer_exclusive_binder: _,
442 kind.hash_stable(hcx, hasher);
446 #[rustc_diagnostic_item = "Ty"]
447 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
449 impl ty::EarlyBoundRegion {
450 /// Does this early bound region have a name? Early bound regions normally
451 /// always have names except when using anonymous lifetimes (`'_`).
452 pub fn has_name(&self) -> bool {
453 self.name != kw::UnderscoreLifetime
458 crate struct PredicateInner<'tcx> {
459 kind: Binder<'tcx, PredicateKind<'tcx>>,
461 /// See the comment for the corresponding field of [TyS].
462 outer_exclusive_binder: ty::DebruijnIndex,
465 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
466 static_assert_size!(PredicateInner<'_>, 48);
468 #[derive(Clone, Copy, Lift)]
469 pub struct Predicate<'tcx> {
470 inner: &'tcx PredicateInner<'tcx>,
473 impl<'tcx> PartialEq for Predicate<'tcx> {
474 fn eq(&self, other: &Self) -> bool {
475 // `self.kind` is always interned.
476 ptr::eq(self.inner, other.inner)
480 impl Hash for Predicate<'_> {
481 fn hash<H: Hasher>(&self, s: &mut H) {
482 (self.inner as *const PredicateInner<'_>).hash(s)
486 impl<'tcx> Eq for Predicate<'tcx> {}
488 impl<'tcx> Predicate<'tcx> {
489 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
491 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
495 pub fn flip_polarity(&self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
499 .map_bound(|kind| match kind {
500 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
501 Some(PredicateKind::Trait(TraitPredicate {
504 polarity: polarity.flip()?,
512 Some(tcx.mk_predicate(kind))
516 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
517 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
521 // The other fields just provide fast access to information that is
522 // also contained in `kind`, so no need to hash them.
524 outer_exclusive_binder: _,
527 kind.hash_stable(hcx, hasher);
531 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
532 #[derive(HashStable, TypeFoldable)]
533 pub enum PredicateKind<'tcx> {
534 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
535 /// the `Self` type of the trait reference and `A`, `B`, and `C`
536 /// would be the type parameters.
537 Trait(TraitPredicate<'tcx>),
540 RegionOutlives(RegionOutlivesPredicate<'tcx>),
543 TypeOutlives(TypeOutlivesPredicate<'tcx>),
545 /// `where <T as TraitRef>::Name == X`, approximately.
546 /// See the `ProjectionPredicate` struct for details.
547 Projection(ProjectionPredicate<'tcx>),
549 /// No syntax: `T` well-formed.
550 WellFormed(GenericArg<'tcx>),
552 /// Trait must be object-safe.
555 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
556 /// for some substitutions `...` and `T` being a closure type.
557 /// Satisfied (or refuted) once we know the closure's kind.
558 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
562 /// This obligation is created most often when we have two
563 /// unresolved type variables and hence don't have enough
564 /// information to process the subtyping obligation yet.
565 Subtype(SubtypePredicate<'tcx>),
567 /// `T1` coerced to `T2`
569 /// Like a subtyping obligation, this is created most often
570 /// when we have two unresolved type variables and hence
571 /// don't have enough information to process the coercion
572 /// obligation yet. At the moment, we actually process coercions
573 /// very much like subtyping and don't handle the full coercion
575 Coerce(CoercePredicate<'tcx>),
577 /// Constant initializer must evaluate successfully.
578 ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
580 /// Constants must be equal. The first component is the const that is expected.
581 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
583 /// Represents a type found in the environment that we can use for implied bounds.
585 /// Only used for Chalk.
586 TypeWellFormedFromEnv(Ty<'tcx>),
589 /// The crate outlives map is computed during typeck and contains the
590 /// outlives of every item in the local crate. You should not use it
591 /// directly, because to do so will make your pass dependent on the
592 /// HIR of every item in the local crate. Instead, use
593 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
595 #[derive(HashStable, Debug)]
596 pub struct CratePredicatesMap<'tcx> {
597 /// For each struct with outlive bounds, maps to a vector of the
598 /// predicate of its outlive bounds. If an item has no outlives
599 /// bounds, it will have no entry.
600 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
603 impl<'tcx> Predicate<'tcx> {
604 /// Performs a substitution suitable for going from a
605 /// poly-trait-ref to supertraits that must hold if that
606 /// poly-trait-ref holds. This is slightly different from a normal
607 /// substitution in terms of what happens with bound regions. See
608 /// lengthy comment below for details.
609 pub fn subst_supertrait(
612 trait_ref: &ty::PolyTraitRef<'tcx>,
613 ) -> Predicate<'tcx> {
614 // The interaction between HRTB and supertraits is not entirely
615 // obvious. Let me walk you (and myself) through an example.
617 // Let's start with an easy case. Consider two traits:
619 // trait Foo<'a>: Bar<'a,'a> { }
620 // trait Bar<'b,'c> { }
622 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
623 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
624 // knew that `Foo<'x>` (for any 'x) then we also know that
625 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
626 // normal substitution.
628 // In terms of why this is sound, the idea is that whenever there
629 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
630 // holds. So if there is an impl of `T:Foo<'a>` that applies to
631 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
634 // Another example to be careful of is this:
636 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
637 // trait Bar1<'b,'c> { }
639 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
640 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
641 // reason is similar to the previous example: any impl of
642 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
643 // basically we would want to collapse the bound lifetimes from
644 // the input (`trait_ref`) and the supertraits.
646 // To achieve this in practice is fairly straightforward. Let's
647 // consider the more complicated scenario:
649 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
650 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
651 // where both `'x` and `'b` would have a DB index of 1.
652 // The substitution from the input trait-ref is therefore going to be
653 // `'a => 'x` (where `'x` has a DB index of 1).
654 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
655 // early-bound parameter and `'b' is a late-bound parameter with a
657 // - If we replace `'a` with `'x` from the input, it too will have
658 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
659 // just as we wanted.
661 // There is only one catch. If we just apply the substitution `'a
662 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
663 // adjust the DB index because we substituting into a binder (it
664 // tries to be so smart...) resulting in `for<'x> for<'b>
665 // Bar1<'x,'b>` (we have no syntax for this, so use your
666 // imagination). Basically the 'x will have DB index of 2 and 'b
667 // will have DB index of 1. Not quite what we want. So we apply
668 // the substitution to the *contents* of the trait reference,
669 // rather than the trait reference itself (put another way, the
670 // substitution code expects equal binding levels in the values
671 // from the substitution and the value being substituted into, and
672 // this trick achieves that).
674 // Working through the second example:
675 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
676 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
677 // We want to end up with:
678 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
680 // 1) We must shift all bound vars in predicate by the length
681 // of trait ref's bound vars. So, we would end up with predicate like
682 // Self: Bar1<'a, '^0.1>
683 // 2) We can then apply the trait substs to this, ending up with
684 // T: Bar1<'^0.0, '^0.1>
685 // 3) Finally, to create the final bound vars, we concatenate the bound
686 // vars of the trait ref with those of the predicate:
688 let bound_pred = self.kind();
689 let pred_bound_vars = bound_pred.bound_vars();
690 let trait_bound_vars = trait_ref.bound_vars();
691 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
693 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
694 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
695 let new = shifted_pred.subst(tcx, trait_ref.skip_binder().substs);
696 // 3) ['x] + ['b] -> ['x, 'b]
698 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
699 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
703 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
704 #[derive(HashStable, TypeFoldable)]
705 pub struct TraitPredicate<'tcx> {
706 pub trait_ref: TraitRef<'tcx>,
708 pub constness: BoundConstness,
710 pub polarity: ImplPolarity,
713 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
715 impl<'tcx> TraitPredicate<'tcx> {
716 pub fn def_id(self) -> DefId {
717 self.trait_ref.def_id
720 pub fn self_ty(self) -> Ty<'tcx> {
721 self.trait_ref.self_ty()
725 impl<'tcx> PolyTraitPredicate<'tcx> {
726 pub fn def_id(self) -> DefId {
727 // Ok to skip binder since trait `DefId` does not care about regions.
728 self.skip_binder().def_id()
731 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
732 self.map_bound(|trait_ref| trait_ref.self_ty())
736 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
737 #[derive(HashStable, TypeFoldable)]
738 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
739 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
740 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
741 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
742 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
744 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
745 /// whether the `a` type is the type that we should label as "expected" when
746 /// presenting user diagnostics.
747 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
748 #[derive(HashStable, TypeFoldable)]
749 pub struct SubtypePredicate<'tcx> {
750 pub a_is_expected: bool,
754 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
756 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
757 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
758 #[derive(HashStable, TypeFoldable)]
759 pub struct CoercePredicate<'tcx> {
763 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
765 /// This kind of predicate has no *direct* correspondent in the
766 /// syntax, but it roughly corresponds to the syntactic forms:
768 /// 1. `T: TraitRef<..., Item = Type>`
769 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
771 /// In particular, form #1 is "desugared" to the combination of a
772 /// normal trait predicate (`T: TraitRef<...>`) and one of these
773 /// predicates. Form #2 is a broader form in that it also permits
774 /// equality between arbitrary types. Processing an instance of
775 /// Form #2 eventually yields one of these `ProjectionPredicate`
776 /// instances to normalize the LHS.
777 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
778 #[derive(HashStable, TypeFoldable)]
779 pub struct ProjectionPredicate<'tcx> {
780 pub projection_ty: ProjectionTy<'tcx>,
784 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
786 impl<'tcx> PolyProjectionPredicate<'tcx> {
787 /// Returns the `DefId` of the trait of the associated item being projected.
789 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
790 self.skip_binder().projection_ty.trait_def_id(tcx)
793 /// Get the [PolyTraitRef] required for this projection to be well formed.
794 /// Note that for generic associated types the predicates of the associated
795 /// type also need to be checked.
797 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
798 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
799 // `self.0.trait_ref` is permitted to have escaping regions.
800 // This is because here `self` has a `Binder` and so does our
801 // return value, so we are preserving the number of binding
803 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
806 pub fn ty(&self) -> Binder<'tcx, Ty<'tcx>> {
807 self.map_bound(|predicate| predicate.ty)
810 /// The `DefId` of the `TraitItem` for the associated type.
812 /// Note that this is not the `DefId` of the `TraitRef` containing this
813 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
814 pub fn projection_def_id(&self) -> DefId {
815 // Ok to skip binder since trait `DefId` does not care about regions.
816 self.skip_binder().projection_ty.item_def_id
820 pub trait ToPolyTraitRef<'tcx> {
821 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
824 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
825 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
826 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
830 pub trait ToPredicate<'tcx> {
831 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
834 impl ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
836 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
837 tcx.mk_predicate(self)
841 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> {
842 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
844 .map_bound(|trait_ref| {
845 PredicateKind::Trait(ty::TraitPredicate {
847 constness: self.constness,
848 polarity: ty::ImplPolarity::Positive,
855 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
856 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
857 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
861 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
862 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
863 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
867 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
868 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
869 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
873 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
874 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
875 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
879 impl<'tcx> Predicate<'tcx> {
880 pub fn to_opt_poly_trait_ref(self) -> Option<ConstnessAnd<PolyTraitRef<'tcx>>> {
881 let predicate = self.kind();
882 match predicate.skip_binder() {
883 PredicateKind::Trait(t) => {
884 Some(ConstnessAnd { constness: t.constness, value: predicate.rebind(t.trait_ref) })
886 PredicateKind::Projection(..)
887 | PredicateKind::Subtype(..)
888 | PredicateKind::Coerce(..)
889 | PredicateKind::RegionOutlives(..)
890 | PredicateKind::WellFormed(..)
891 | PredicateKind::ObjectSafe(..)
892 | PredicateKind::ClosureKind(..)
893 | PredicateKind::TypeOutlives(..)
894 | PredicateKind::ConstEvaluatable(..)
895 | PredicateKind::ConstEquate(..)
896 | PredicateKind::TypeWellFormedFromEnv(..) => None,
900 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
901 let predicate = self.kind();
902 match predicate.skip_binder() {
903 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
904 PredicateKind::Trait(..)
905 | PredicateKind::Projection(..)
906 | PredicateKind::Subtype(..)
907 | PredicateKind::Coerce(..)
908 | PredicateKind::RegionOutlives(..)
909 | PredicateKind::WellFormed(..)
910 | PredicateKind::ObjectSafe(..)
911 | PredicateKind::ClosureKind(..)
912 | PredicateKind::ConstEvaluatable(..)
913 | PredicateKind::ConstEquate(..)
914 | PredicateKind::TypeWellFormedFromEnv(..) => None,
919 /// Represents the bounds declared on a particular set of type
920 /// parameters. Should eventually be generalized into a flag list of
921 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
922 /// `GenericPredicates` by using the `instantiate` method. Note that this method
923 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
924 /// the `GenericPredicates` are expressed in terms of the bound type
925 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
926 /// represented a set of bounds for some particular instantiation,
927 /// meaning that the generic parameters have been substituted with
932 /// struct Foo<T, U: Bar<T>> { ... }
934 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
935 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
936 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
937 /// [usize:Bar<isize>]]`.
938 #[derive(Clone, Debug, TypeFoldable)]
939 pub struct InstantiatedPredicates<'tcx> {
940 pub predicates: Vec<Predicate<'tcx>>,
941 pub spans: Vec<Span>,
944 impl<'tcx> InstantiatedPredicates<'tcx> {
945 pub fn empty() -> InstantiatedPredicates<'tcx> {
946 InstantiatedPredicates { predicates: vec![], spans: vec![] }
949 pub fn is_empty(&self) -> bool {
950 self.predicates.is_empty()
954 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable, TypeFoldable)]
955 pub struct OpaqueTypeKey<'tcx> {
957 pub substs: SubstsRef<'tcx>,
960 rustc_index::newtype_index! {
961 /// "Universes" are used during type- and trait-checking in the
962 /// presence of `for<..>` binders to control what sets of names are
963 /// visible. Universes are arranged into a tree: the root universe
964 /// contains names that are always visible. Each child then adds a new
965 /// set of names that are visible, in addition to those of its parent.
966 /// We say that the child universe "extends" the parent universe with
969 /// To make this more concrete, consider this program:
973 /// fn bar<T>(x: T) {
974 /// let y: for<'a> fn(&'a u8, Foo) = ...;
978 /// The struct name `Foo` is in the root universe U0. But the type
979 /// parameter `T`, introduced on `bar`, is in an extended universe U1
980 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
981 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
982 /// region `'a` is in a universe U2 that extends U1, because we can
983 /// name it inside the fn type but not outside.
985 /// Universes are used to do type- and trait-checking around these
986 /// "forall" binders (also called **universal quantification**). The
987 /// idea is that when, in the body of `bar`, we refer to `T` as a
988 /// type, we aren't referring to any type in particular, but rather a
989 /// kind of "fresh" type that is distinct from all other types we have
990 /// actually declared. This is called a **placeholder** type, and we
991 /// use universes to talk about this. In other words, a type name in
992 /// universe 0 always corresponds to some "ground" type that the user
993 /// declared, but a type name in a non-zero universe is a placeholder
994 /// type -- an idealized representative of "types in general" that we
995 /// use for checking generic functions.
996 pub struct UniverseIndex {
998 DEBUG_FORMAT = "U{}",
1002 impl UniverseIndex {
1003 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1005 /// Returns the "next" universe index in order -- this new index
1006 /// is considered to extend all previous universes. This
1007 /// corresponds to entering a `forall` quantifier. So, for
1008 /// example, suppose we have this type in universe `U`:
1011 /// for<'a> fn(&'a u32)
1014 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1015 /// new universe that extends `U` -- in this new universe, we can
1016 /// name the region `'a`, but that region was not nameable from
1017 /// `U` because it was not in scope there.
1018 pub fn next_universe(self) -> UniverseIndex {
1019 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1022 /// Returns `true` if `self` can name a name from `other` -- in other words,
1023 /// if the set of names in `self` is a superset of those in
1024 /// `other` (`self >= other`).
1025 pub fn can_name(self, other: UniverseIndex) -> bool {
1026 self.private >= other.private
1029 /// Returns `true` if `self` cannot name some names from `other` -- in other
1030 /// words, if the set of names in `self` is a strict subset of
1031 /// those in `other` (`self < other`).
1032 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1033 self.private < other.private
1037 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1038 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1039 /// regions/types/consts within the same universe simply have an unknown relationship to one
1041 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1042 pub struct Placeholder<T> {
1043 pub universe: UniverseIndex,
1047 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1049 T: HashStable<StableHashingContext<'a>>,
1051 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1052 self.universe.hash_stable(hcx, hasher);
1053 self.name.hash_stable(hcx, hasher);
1057 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1059 pub type PlaceholderType = Placeholder<BoundVar>;
1061 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1062 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1063 pub struct BoundConst<'tcx> {
1068 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1070 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1071 /// the `DefId` of the generic parameter it instantiates.
1073 /// This is used to avoid calls to `type_of` for const arguments during typeck
1074 /// which cause cycle errors.
1079 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1080 /// // ^ const parameter
1084 /// fn foo<const M: u8>(&self) -> usize { 42 }
1085 /// // ^ const parameter
1090 /// let _b = a.foo::<{ 3 + 7 }>();
1091 /// // ^^^^^^^^^ const argument
1095 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1096 /// which `foo` is used until we know the type of `a`.
1098 /// We only know the type of `a` once we are inside of `typeck(main)`.
1099 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1100 /// requires us to evaluate the const argument.
1102 /// To evaluate that const argument we need to know its type,
1103 /// which we would get using `type_of(const_arg)`. This requires us to
1104 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1105 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1106 /// which results in a cycle.
1108 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1110 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1111 /// already resolved `foo` so we know which const parameter this argument instantiates.
1112 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1113 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1114 /// trivial to compute.
1116 /// If we now want to use that constant in a place which potentionally needs its type
1117 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1118 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1119 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1120 /// to get the type of `did`.
1121 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1122 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1123 #[derive(Hash, HashStable)]
1124 pub struct WithOptConstParam<T> {
1126 /// The `DefId` of the corresponding generic parameter in case `did` is
1127 /// a const argument.
1129 /// Note that even if `did` is a const argument, this may still be `None`.
1130 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1131 /// to potentially update `param_did` in the case it is `None`.
1132 pub const_param_did: Option<DefId>,
1135 impl<T> WithOptConstParam<T> {
1136 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1138 pub fn unknown(did: T) -> WithOptConstParam<T> {
1139 WithOptConstParam { did, const_param_did: None }
1143 impl WithOptConstParam<LocalDefId> {
1144 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1145 /// `None` otherwise.
1147 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1148 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1151 /// In case `self` is unknown but `self.did` is a const argument, this returns
1152 /// a `WithOptConstParam` with the correct `const_param_did`.
1154 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1155 if self.const_param_did.is_none() {
1156 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1157 return Some(WithOptConstParam { did: self.did, const_param_did });
1164 pub fn to_global(self) -> WithOptConstParam<DefId> {
1165 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1168 pub fn def_id_for_type_of(self) -> DefId {
1169 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1173 impl WithOptConstParam<DefId> {
1174 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1177 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1180 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1181 if let Some(param_did) = self.const_param_did {
1182 if let Some(did) = self.did.as_local() {
1183 return Some((did, param_did));
1190 pub fn is_local(self) -> bool {
1194 pub fn def_id_for_type_of(self) -> DefId {
1195 self.const_param_did.unwrap_or(self.did)
1199 /// When type checking, we use the `ParamEnv` to track
1200 /// details about the set of where-clauses that are in scope at this
1201 /// particular point.
1202 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1203 pub struct ParamEnv<'tcx> {
1204 /// This packs both caller bounds and the reveal enum into one pointer.
1206 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1207 /// basically the set of bounds on the in-scope type parameters, translated
1208 /// into `Obligation`s, and elaborated and normalized.
1210 /// Use the `caller_bounds()` method to access.
1212 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1213 /// want `Reveal::All`.
1215 /// Note: This is packed, use the reveal() method to access it.
1216 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, traits::Reveal, true>,
1219 unsafe impl rustc_data_structures::tagged_ptr::Tag for traits::Reveal {
1220 const BITS: usize = 1;
1222 fn into_usize(self) -> usize {
1224 traits::Reveal::UserFacing => 0,
1225 traits::Reveal::All => 1,
1229 unsafe fn from_usize(ptr: usize) -> Self {
1231 0 => traits::Reveal::UserFacing,
1232 1 => traits::Reveal::All,
1233 _ => std::hint::unreachable_unchecked(),
1238 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1239 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1240 f.debug_struct("ParamEnv")
1241 .field("caller_bounds", &self.caller_bounds())
1242 .field("reveal", &self.reveal())
1247 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1248 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1249 self.caller_bounds().hash_stable(hcx, hasher);
1250 self.reveal().hash_stable(hcx, hasher);
1254 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1255 fn super_fold_with<F: ty::fold::TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1256 ParamEnv::new(self.caller_bounds().fold_with(folder), self.reveal().fold_with(folder))
1259 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1260 self.caller_bounds().visit_with(visitor)?;
1261 self.reveal().visit_with(visitor)
1265 impl<'tcx> ParamEnv<'tcx> {
1266 /// Construct a trait environment suitable for contexts where
1267 /// there are no where-clauses in scope. Hidden types (like `impl
1268 /// Trait`) are left hidden, so this is suitable for ordinary
1271 pub fn empty() -> Self {
1272 Self::new(List::empty(), Reveal::UserFacing)
1276 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1277 self.packed.pointer()
1281 pub fn reveal(self) -> traits::Reveal {
1285 /// Construct a trait environment with no where-clauses in scope
1286 /// where the values of all `impl Trait` and other hidden types
1287 /// are revealed. This is suitable for monomorphized, post-typeck
1288 /// environments like codegen or doing optimizations.
1290 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1291 /// or invoke `param_env.with_reveal_all()`.
1293 pub fn reveal_all() -> Self {
1294 Self::new(List::empty(), Reveal::All)
1297 /// Construct a trait environment with the given set of predicates.
1299 pub fn new(caller_bounds: &'tcx List<Predicate<'tcx>>, reveal: Reveal) -> Self {
1300 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, reveal) }
1303 pub fn with_user_facing(mut self) -> Self {
1304 self.packed.set_tag(Reveal::UserFacing);
1308 /// Returns a new parameter environment with the same clauses, but
1309 /// which "reveals" the true results of projections in all cases
1310 /// (even for associated types that are specializable). This is
1311 /// the desired behavior during codegen and certain other special
1312 /// contexts; normally though we want to use `Reveal::UserFacing`,
1313 /// which is the default.
1314 /// All opaque types in the caller_bounds of the `ParamEnv`
1315 /// will be normalized to their underlying types.
1316 /// See PR #65989 and issue #65918 for more details
1317 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1318 if self.packed.tag() == traits::Reveal::All {
1322 ParamEnv::new(tcx.normalize_opaque_types(self.caller_bounds()), Reveal::All)
1325 /// Returns this same environment but with no caller bounds.
1327 pub fn without_caller_bounds(self) -> Self {
1328 Self::new(List::empty(), self.reveal())
1331 /// Creates a suitable environment in which to perform trait
1332 /// queries on the given value. When type-checking, this is simply
1333 /// the pair of the environment plus value. But when reveal is set to
1334 /// All, then if `value` does not reference any type parameters, we will
1335 /// pair it with the empty environment. This improves caching and is generally
1338 /// N.B., we preserve the environment when type-checking because it
1339 /// is possible for the user to have wacky where-clauses like
1340 /// `where Box<u32>: Copy`, which are clearly never
1341 /// satisfiable. We generally want to behave as if they were true,
1342 /// although the surrounding function is never reachable.
1343 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1344 match self.reveal() {
1345 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1348 if value.is_known_global() {
1349 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1351 ParamEnvAnd { param_env: self, value }
1358 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1359 pub struct ConstnessAnd<T> {
1360 pub constness: BoundConstness,
1364 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1365 // the constness of trait bounds is being propagated correctly.
1366 pub trait WithConstness: Sized {
1368 fn with_constness(self, constness: BoundConstness) -> ConstnessAnd<Self> {
1369 ConstnessAnd { constness, value: self }
1373 fn with_const_if_const(self) -> ConstnessAnd<Self> {
1374 self.with_constness(BoundConstness::ConstIfConst)
1378 fn without_const(self) -> ConstnessAnd<Self> {
1379 self.with_constness(BoundConstness::NotConst)
1383 impl<T> WithConstness for T {}
1385 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1386 pub struct ParamEnvAnd<'tcx, T> {
1387 pub param_env: ParamEnv<'tcx>,
1391 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1392 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1393 (self.param_env, self.value)
1397 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1399 T: HashStable<StableHashingContext<'a>>,
1401 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1402 let ParamEnvAnd { ref param_env, ref value } = *self;
1404 param_env.hash_stable(hcx, hasher);
1405 value.hash_stable(hcx, hasher);
1409 #[derive(Copy, Clone, Debug, HashStable)]
1410 pub struct Destructor {
1411 /// The `DefId` of the destructor method
1413 /// The constness of the destructor method
1414 pub constness: hir::Constness,
1418 #[derive(HashStable)]
1419 pub struct VariantFlags: u32 {
1420 const NO_VARIANT_FLAGS = 0;
1421 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1422 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1423 /// Indicates whether this variant was obtained as part of recovering from
1424 /// a syntactic error. May be incomplete or bogus.
1425 const IS_RECOVERED = 1 << 1;
1429 /// Definition of a variant -- a struct's fields or an enum variant.
1430 #[derive(Debug, HashStable)]
1431 pub struct VariantDef {
1432 /// `DefId` that identifies the variant itself.
1433 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1435 /// `DefId` that identifies the variant's constructor.
1436 /// If this variant is a struct variant, then this is `None`.
1437 pub ctor_def_id: Option<DefId>,
1438 /// Variant or struct name.
1439 #[stable_hasher(project(name))]
1441 /// Discriminant of this variant.
1442 pub discr: VariantDiscr,
1443 /// Fields of this variant.
1444 pub fields: Vec<FieldDef>,
1445 /// Type of constructor of variant.
1446 pub ctor_kind: CtorKind,
1447 /// Flags of the variant (e.g. is field list non-exhaustive)?
1448 flags: VariantFlags,
1452 /// Creates a new `VariantDef`.
1454 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1455 /// represents an enum variant).
1457 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1458 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1460 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1461 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1462 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1463 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1464 /// built-in trait), and we do not want to load attributes twice.
1466 /// If someone speeds up attribute loading to not be a performance concern, they can
1467 /// remove this hack and use the constructor `DefId` everywhere.
1470 variant_did: Option<DefId>,
1471 ctor_def_id: Option<DefId>,
1472 discr: VariantDiscr,
1473 fields: Vec<FieldDef>,
1474 ctor_kind: CtorKind,
1478 is_field_list_non_exhaustive: bool,
1481 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1482 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1483 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1486 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1487 if is_field_list_non_exhaustive {
1488 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1492 flags |= VariantFlags::IS_RECOVERED;
1496 def_id: variant_did.unwrap_or(parent_did),
1506 /// Is this field list non-exhaustive?
1508 pub fn is_field_list_non_exhaustive(&self) -> bool {
1509 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1512 /// Was this variant obtained as part of recovering from a syntactic error?
1514 pub fn is_recovered(&self) -> bool {
1515 self.flags.intersects(VariantFlags::IS_RECOVERED)
1519 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1520 pub enum VariantDiscr {
1521 /// Explicit value for this variant, i.e., `X = 123`.
1522 /// The `DefId` corresponds to the embedded constant.
1525 /// The previous variant's discriminant plus one.
1526 /// For efficiency reasons, the distance from the
1527 /// last `Explicit` discriminant is being stored,
1528 /// or `0` for the first variant, if it has none.
1532 #[derive(Debug, HashStable)]
1533 pub struct FieldDef {
1535 #[stable_hasher(project(name))]
1537 pub vis: Visibility,
1541 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1542 pub struct ReprFlags: u8 {
1543 const IS_C = 1 << 0;
1544 const IS_SIMD = 1 << 1;
1545 const IS_TRANSPARENT = 1 << 2;
1546 // Internal only for now. If true, don't reorder fields.
1547 const IS_LINEAR = 1 << 3;
1548 // If true, don't expose any niche to type's context.
1549 const HIDE_NICHE = 1 << 4;
1550 // If true, the type's layout can be randomized using
1551 // the seed stored in `ReprOptions.layout_seed`
1552 const RANDOMIZE_LAYOUT = 1 << 5;
1553 // Any of these flags being set prevent field reordering optimisation.
1554 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
1555 ReprFlags::IS_SIMD.bits |
1556 ReprFlags::IS_LINEAR.bits;
1560 /// Represents the repr options provided by the user,
1561 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
1562 pub struct ReprOptions {
1563 pub int: Option<attr::IntType>,
1564 pub align: Option<Align>,
1565 pub pack: Option<Align>,
1566 pub flags: ReprFlags,
1567 /// The seed to be used for randomizing a type's layout
1569 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
1570 /// be the "most accurate" hash as it'd encompass the item and crate
1571 /// hash without loss, but it does pay the price of being larger.
1572 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
1573 /// purposes (primarily `-Z randomize-layout`)
1574 pub field_shuffle_seed: u64,
1578 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1579 let mut flags = ReprFlags::empty();
1580 let mut size = None;
1581 let mut max_align: Option<Align> = None;
1582 let mut min_pack: Option<Align> = None;
1584 // Generate a deterministically-derived seed from the item's path hash
1585 // to allow for cross-crate compilation to actually work
1586 let field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
1588 for attr in tcx.get_attrs(did).iter() {
1589 for r in attr::find_repr_attrs(&tcx.sess, attr) {
1590 flags.insert(match r {
1591 attr::ReprC => ReprFlags::IS_C,
1592 attr::ReprPacked(pack) => {
1593 let pack = Align::from_bytes(pack as u64).unwrap();
1594 min_pack = Some(if let Some(min_pack) = min_pack {
1601 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1602 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
1603 attr::ReprSimd => ReprFlags::IS_SIMD,
1604 attr::ReprInt(i) => {
1608 attr::ReprAlign(align) => {
1609 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
1616 // If `-Z randomize-layout` was enabled for the type definition then we can
1617 // consider performing layout randomization
1618 if tcx.sess.opts.debugging_opts.randomize_layout {
1619 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1622 // This is here instead of layout because the choice must make it into metadata.
1623 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
1624 flags.insert(ReprFlags::IS_LINEAR);
1627 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1631 pub fn simd(&self) -> bool {
1632 self.flags.contains(ReprFlags::IS_SIMD)
1636 pub fn c(&self) -> bool {
1637 self.flags.contains(ReprFlags::IS_C)
1641 pub fn packed(&self) -> bool {
1646 pub fn transparent(&self) -> bool {
1647 self.flags.contains(ReprFlags::IS_TRANSPARENT)
1651 pub fn linear(&self) -> bool {
1652 self.flags.contains(ReprFlags::IS_LINEAR)
1656 pub fn hide_niche(&self) -> bool {
1657 self.flags.contains(ReprFlags::HIDE_NICHE)
1660 /// Returns the discriminant type, given these `repr` options.
1661 /// This must only be called on enums!
1662 pub fn discr_type(&self) -> attr::IntType {
1663 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1666 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
1667 /// layout" optimizations, such as representing `Foo<&T>` as a
1669 pub fn inhibit_enum_layout_opt(&self) -> bool {
1670 self.c() || self.int.is_some()
1673 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
1674 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
1675 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
1676 if let Some(pack) = self.pack {
1677 if pack.bytes() == 1 {
1682 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
1685 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
1686 /// was enabled for its declaration crate
1687 pub fn can_randomize_type_layout(&self) -> bool {
1688 !self.inhibit_struct_field_reordering_opt()
1689 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
1692 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
1693 pub fn inhibit_union_abi_opt(&self) -> bool {
1698 impl<'tcx> FieldDef {
1699 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
1700 /// typically obtained via the second field of `TyKind::AdtDef`.
1701 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
1702 tcx.type_of(self.did).subst(tcx, subst)
1706 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
1708 #[derive(Debug, PartialEq, Eq)]
1709 pub enum ImplOverlapKind {
1710 /// These impls are always allowed to overlap.
1712 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1715 /// These impls are allowed to overlap, but that raises
1716 /// an issue #33140 future-compatibility warning.
1718 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
1719 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
1721 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
1722 /// that difference, making what reduces to the following set of impls:
1726 /// impl Trait for dyn Send + Sync {}
1727 /// impl Trait for dyn Sync + Send {}
1730 /// Obviously, once we made these types be identical, that code causes a coherence
1731 /// error and a fairly big headache for us. However, luckily for us, the trait
1732 /// `Trait` used in this case is basically a marker trait, and therefore having
1733 /// overlapping impls for it is sound.
1735 /// To handle this, we basically regard the trait as a marker trait, with an additional
1736 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
1737 /// it has the following restrictions:
1739 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
1741 /// 2. The trait-ref of both impls must be equal.
1742 /// 3. The trait-ref of both impls must be a trait object type consisting only of
1744 /// 4. Neither of the impls can have any where-clauses.
1746 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
1750 impl<'tcx> TyCtxt<'tcx> {
1751 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1752 self.typeck(self.hir().body_owner_def_id(body))
1755 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1756 self.associated_items(id)
1757 .in_definition_order()
1758 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
1761 fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
1762 self.hir().get_if_local(def_id).and_then(|node| node.ident())
1765 fn item_name_from_def_id(self, def_id: DefId) -> Option<Symbol> {
1766 if def_id.index == CRATE_DEF_INDEX {
1767 Some(self.crate_name(def_id.krate))
1769 let def_key = self.def_key(def_id);
1770 match def_key.disambiguated_data.data {
1771 // The name of a constructor is that of its parent.
1772 rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId {
1773 krate: def_id.krate,
1774 index: def_key.parent.unwrap(),
1776 _ => def_key.disambiguated_data.data.get_opt_name(),
1781 /// Look up the name of an item across crates. This does not look at HIR.
1783 /// When possible, this function should be used for cross-crate lookups over
1784 /// [`opt_item_name`] to avoid invalidating the incremental cache. If you
1785 /// need to handle items without a name, or HIR items that will not be
1786 /// serialized cross-crate, or if you need the span of the item, use
1787 /// [`opt_item_name`] instead.
1789 /// [`opt_item_name`]: Self::opt_item_name
1790 pub fn item_name(self, id: DefId) -> Symbol {
1791 // Look at cross-crate items first to avoid invalidating the incremental cache
1792 // unless we have to.
1793 self.item_name_from_def_id(id).unwrap_or_else(|| {
1794 bug!("item_name: no name for {:?}", self.def_path(id));
1798 /// Look up the name and span of an item or [`Node`].
1800 /// See [`item_name`][Self::item_name] for more information.
1801 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
1802 // Look at the HIR first so the span will be correct if this is a local item.
1803 self.item_name_from_hir(def_id)
1804 .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span))
1807 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
1808 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
1809 Some(self.associated_item(def_id))
1815 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
1816 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
1819 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
1820 variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id))
1823 /// Returns `true` if the impls are the same polarity and the trait either
1824 /// has no items or is annotated `#[marker]` and prevents item overrides.
1825 pub fn impls_are_allowed_to_overlap(
1829 ) -> Option<ImplOverlapKind> {
1830 // If either trait impl references an error, they're allowed to overlap,
1831 // as one of them essentially doesn't exist.
1832 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
1833 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
1835 return Some(ImplOverlapKind::Permitted { marker: false });
1838 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
1839 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
1840 // `#[rustc_reservation_impl]` impls don't overlap with anything
1842 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
1845 return Some(ImplOverlapKind::Permitted { marker: false });
1847 (ImplPolarity::Positive, ImplPolarity::Negative)
1848 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
1849 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
1851 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
1856 (ImplPolarity::Positive, ImplPolarity::Positive)
1857 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
1860 let is_marker_overlap = {
1861 let is_marker_impl = |def_id: DefId| -> bool {
1862 let trait_ref = self.impl_trait_ref(def_id);
1863 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
1865 is_marker_impl(def_id1) && is_marker_impl(def_id2)
1868 if is_marker_overlap {
1870 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
1873 Some(ImplOverlapKind::Permitted { marker: true })
1875 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
1876 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
1877 if self_ty1 == self_ty2 {
1879 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
1882 return Some(ImplOverlapKind::Issue33140);
1885 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
1886 def_id1, def_id2, self_ty1, self_ty2
1892 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
1897 /// Returns `ty::VariantDef` if `res` refers to a struct,
1898 /// or variant or their constructors, panics otherwise.
1899 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
1901 Res::Def(DefKind::Variant, did) => {
1902 let enum_did = self.parent(did).unwrap();
1903 self.adt_def(enum_did).variant_with_id(did)
1905 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
1906 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
1907 let variant_did = self.parent(variant_ctor_did).unwrap();
1908 let enum_did = self.parent(variant_did).unwrap();
1909 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
1911 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
1912 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
1913 self.adt_def(struct_did).non_enum_variant()
1915 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
1919 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
1920 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
1922 ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
1925 | DefKind::AssocConst
1927 | DefKind::AnonConst => self.mir_for_ctfe_opt_const_arg(def),
1928 // If the caller wants `mir_for_ctfe` of a function they should not be using
1929 // `instance_mir`, so we'll assume const fn also wants the optimized version.
1931 assert_eq!(def.const_param_did, None);
1932 self.optimized_mir(def.did)
1935 ty::InstanceDef::VtableShim(..)
1936 | ty::InstanceDef::ReifyShim(..)
1937 | ty::InstanceDef::Intrinsic(..)
1938 | ty::InstanceDef::FnPtrShim(..)
1939 | ty::InstanceDef::Virtual(..)
1940 | ty::InstanceDef::ClosureOnceShim { .. }
1941 | ty::InstanceDef::DropGlue(..)
1942 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
1946 /// Gets the attributes of a definition.
1947 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
1948 if let Some(did) = did.as_local() {
1949 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
1951 self.item_attrs(did)
1955 /// Determines whether an item is annotated with an attribute.
1956 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
1957 self.sess.contains_name(&self.get_attrs(did), attr)
1960 /// Determines whether an item is annotated with `doc(hidden)`.
1961 pub fn is_doc_hidden(self, did: DefId) -> bool {
1964 .filter_map(|attr| if attr.has_name(sym::doc) { attr.meta_item_list() } else { None })
1965 .any(|items| items.iter().any(|item| item.has_name(sym::hidden)))
1968 /// Returns `true` if this is an `auto trait`.
1969 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
1970 self.trait_def(trait_def_id).has_auto_impl
1973 /// Returns layout of a generator. Layout might be unavailable if the
1974 /// generator is tainted by errors.
1975 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
1976 self.optimized_mir(def_id).generator_layout()
1979 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
1980 /// If it implements no trait, returns `None`.
1981 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
1982 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
1985 /// If the given defid describes a method belonging to an impl, returns the
1986 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
1987 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
1988 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
1989 TraitContainer(_) => None,
1990 ImplContainer(def_id) => Some(def_id),
1994 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
1995 /// with the name of the crate containing the impl.
1996 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
1997 if let Some(impl_did) = impl_did.as_local() {
1998 let hir_id = self.hir().local_def_id_to_hir_id(impl_did);
1999 Ok(self.hir().span(hir_id))
2001 Err(self.crate_name(impl_did.krate))
2005 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2006 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2007 /// definition's parent/scope to perform comparison.
2008 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2009 // We could use `Ident::eq` here, but we deliberately don't. The name
2010 // comparison fails frequently, and we want to avoid the expensive
2011 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2012 use_name.name == def_name.name
2016 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2019 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2020 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2024 pub fn adjust_ident_and_get_scope(
2029 ) -> (Ident, DefId) {
2032 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2033 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2034 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2038 pub fn is_object_safe(self, key: DefId) -> bool {
2039 self.object_safety_violations(key).is_empty()
2043 /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition.
2044 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
2045 if let Some(def_id) = def_id.as_local() {
2046 if let Node::Item(item) = tcx.hir().get(tcx.hir().local_def_id_to_hir_id(def_id)) {
2047 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2048 return opaque_ty.impl_trait_fn;
2055 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2057 ast::IntTy::Isize => IntTy::Isize,
2058 ast::IntTy::I8 => IntTy::I8,
2059 ast::IntTy::I16 => IntTy::I16,
2060 ast::IntTy::I32 => IntTy::I32,
2061 ast::IntTy::I64 => IntTy::I64,
2062 ast::IntTy::I128 => IntTy::I128,
2066 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2068 ast::UintTy::Usize => UintTy::Usize,
2069 ast::UintTy::U8 => UintTy::U8,
2070 ast::UintTy::U16 => UintTy::U16,
2071 ast::UintTy::U32 => UintTy::U32,
2072 ast::UintTy::U64 => UintTy::U64,
2073 ast::UintTy::U128 => UintTy::U128,
2077 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2079 ast::FloatTy::F32 => FloatTy::F32,
2080 ast::FloatTy::F64 => FloatTy::F64,
2084 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2086 IntTy::Isize => ast::IntTy::Isize,
2087 IntTy::I8 => ast::IntTy::I8,
2088 IntTy::I16 => ast::IntTy::I16,
2089 IntTy::I32 => ast::IntTy::I32,
2090 IntTy::I64 => ast::IntTy::I64,
2091 IntTy::I128 => ast::IntTy::I128,
2095 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2097 UintTy::Usize => ast::UintTy::Usize,
2098 UintTy::U8 => ast::UintTy::U8,
2099 UintTy::U16 => ast::UintTy::U16,
2100 UintTy::U32 => ast::UintTy::U32,
2101 UintTy::U64 => ast::UintTy::U64,
2102 UintTy::U128 => ast::UintTy::U128,
2106 pub fn provide(providers: &mut ty::query::Providers) {
2107 closure::provide(providers);
2108 context::provide(providers);
2109 erase_regions::provide(providers);
2110 layout::provide(providers);
2111 util::provide(providers);
2112 print::provide(providers);
2113 super::util::bug::provide(providers);
2114 super::middle::provide(providers);
2115 *providers = ty::query::Providers {
2116 trait_impls_of: trait_def::trait_impls_of_provider,
2117 type_uninhabited_from: inhabitedness::type_uninhabited_from,
2118 const_param_default: consts::const_param_default,
2119 vtable_allocation: vtable::vtable_allocation_provider,
2124 /// A map for the local crate mapping each type to a vector of its
2125 /// inherent impls. This is not meant to be used outside of coherence;
2126 /// rather, you should request the vector for a specific type via
2127 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2128 /// (constructing this map requires touching the entire crate).
2129 #[derive(Clone, Debug, Default, HashStable)]
2130 pub struct CrateInherentImpls {
2131 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2134 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2135 pub struct SymbolName<'tcx> {
2136 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2137 pub name: &'tcx str,
2140 impl<'tcx> SymbolName<'tcx> {
2141 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2143 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2148 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2149 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2150 fmt::Display::fmt(&self.name, fmt)
2154 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2155 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2156 fmt::Display::fmt(&self.name, fmt)
2160 #[derive(Debug, Default, Copy, Clone)]
2161 pub struct FoundRelationships {
2162 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2163 /// obligation, where:
2165 /// * `Foo` is not `Sized`
2166 /// * `(): Foo` may be satisfied
2167 pub self_in_trait: bool,
2168 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2169 /// _>::AssocType = ?T`