1 //! Defines how the compiler represents types internally.
3 //! Two important entities in this module are:
5 //! - [`rustc_middle::ty::Ty`], used to represent the semantics of a type.
6 //! - [`rustc_middle::ty::TyCtxt`], the central data structure in the compiler.
8 //! For more information, see ["The `ty` module: representing types"] in the rustc-dev-guide.
10 //! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html
12 pub use self::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeVisitor};
13 pub use self::AssocItemContainer::*;
14 pub use self::BorrowKind::*;
15 pub use self::IntVarValue::*;
16 pub use self::Variance::*;
17 use crate::metadata::ModChild;
18 use crate::middle::privacy::AccessLevels;
19 use crate::mir::{Body, GeneratorLayout};
20 use crate::traits::{self, Reveal};
22 use crate::ty::fast_reject::SimplifiedType;
23 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
24 use crate::ty::util::Discr;
29 use rustc_attr as attr;
30 use rustc_data_structures::fingerprint::Fingerprint;
31 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
32 use rustc_data_structures::intern::{Interned, WithStableHash};
33 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
34 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
36 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
37 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap};
39 use rustc_macros::HashStable;
40 use rustc_query_system::ich::StableHashingContext;
41 use rustc_session::cstore::CrateStoreDyn;
42 use rustc_span::symbol::{kw, sym, Ident, Symbol};
44 use rustc_target::abi::Align;
49 use std::ops::ControlFlow;
52 pub use crate::ty::diagnostics::*;
53 pub use rustc_type_ir::InferTy::*;
54 pub use rustc_type_ir::*;
56 pub use self::binding::BindingMode;
57 pub use self::binding::BindingMode::*;
58 pub use self::closure::{
59 is_ancestor_or_same_capture, place_to_string_for_capture, BorrowKind, CaptureInfo,
60 CapturedPlace, ClosureKind, MinCaptureInformationMap, MinCaptureList,
61 RootVariableMinCaptureList, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath,
64 pub use self::consts::{
65 Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, Unevaluated, ValTree,
67 pub use self::context::{
68 tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
69 CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorDiagnosticData,
70 GeneratorInteriorTypeCause, GlobalCtxt, Lift, OnDiskCache, TyCtxt, TypeckResults, UserType,
71 UserTypeAnnotationIndex,
73 pub use self::instance::{Instance, InstanceDef};
74 pub use self::list::List;
75 pub use self::sty::BoundRegionKind::*;
76 pub use self::sty::RegionKind::*;
77 pub use self::sty::TyKind::*;
79 Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind,
80 CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBinder, EarlyBoundRegion,
81 ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig,
82 GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts, InlineConstSubstsParts, ParamConst,
83 ParamTy, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig,
84 PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut,
85 UpvarSubsts, VarianceDiagInfo,
87 pub use self::trait_def::TraitDef;
98 pub mod inhabitedness;
100 pub mod normalize_erasing_regions;
121 mod structural_impls;
126 pub type RegisteredTools = FxHashSet<Ident>;
129 pub struct ResolverOutputs {
130 pub definitions: rustc_hir::definitions::Definitions,
131 pub cstore: Box<CrateStoreDyn>,
132 pub visibilities: FxHashMap<LocalDefId, Visibility>,
133 /// This field is used to decide whether we should make `PRIVATE_IN_PUBLIC` a hard error.
134 pub has_pub_restricted: bool,
135 pub access_levels: AccessLevels,
136 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
137 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
138 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
139 pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
140 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
141 /// Extern prelude entries. The value is `true` if the entry was introduced
142 /// via `extern crate` item and not `--extern` option or compiler built-in.
143 pub extern_prelude: FxHashMap<Symbol, bool>,
144 pub main_def: Option<MainDefinition>,
145 pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
146 /// A list of proc macro LocalDefIds, written out in the order in which
147 /// they are declared in the static array generated by proc_macro_harness.
148 pub proc_macros: Vec<LocalDefId>,
149 /// Mapping from ident span to path span for paths that don't exist as written, but that
150 /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
151 pub confused_type_with_std_module: FxHashMap<Span, Span>,
152 pub registered_tools: RegisteredTools,
155 #[derive(Clone, Copy, Debug)]
156 pub struct MainDefinition {
157 pub res: Res<ast::NodeId>,
162 impl MainDefinition {
163 pub fn opt_fn_def_id(self) -> Option<DefId> {
164 if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
168 /// The "header" of an impl is everything outside the body: a Self type, a trait
169 /// ref (in the case of a trait impl), and a set of predicates (from the
170 /// bounds / where-clauses).
171 #[derive(Clone, Debug, TypeFoldable)]
172 pub struct ImplHeader<'tcx> {
173 pub impl_def_id: DefId,
174 pub self_ty: Ty<'tcx>,
175 pub trait_ref: Option<TraitRef<'tcx>>,
176 pub predicates: Vec<Predicate<'tcx>>,
179 #[derive(Copy, Clone, Debug, TypeFoldable)]
180 pub enum ImplSubject<'tcx> {
181 Trait(TraitRef<'tcx>),
197 pub enum ImplPolarity {
198 /// `impl Trait for Type`
200 /// `impl !Trait for Type`
202 /// `#[rustc_reservation_impl] impl Trait for Type`
204 /// This is a "stability hack", not a real Rust feature.
205 /// See #64631 for details.
210 /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
211 pub fn flip(&self) -> Option<ImplPolarity> {
213 ImplPolarity::Positive => Some(ImplPolarity::Negative),
214 ImplPolarity::Negative => Some(ImplPolarity::Positive),
215 ImplPolarity::Reservation => None,
220 impl fmt::Display for ImplPolarity {
221 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
223 Self::Positive => f.write_str("positive"),
224 Self::Negative => f.write_str("negative"),
225 Self::Reservation => f.write_str("reservation"),
230 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
231 pub enum Visibility {
232 /// Visible everywhere (including in other crates).
234 /// Visible only in the given crate-local module.
236 /// Not visible anywhere in the local crate. This is the visibility of private external items.
240 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
241 pub enum BoundConstness {
244 /// `T: ~const Trait`
246 /// Requires resolving to const only when we are in a const context.
250 impl BoundConstness {
251 /// Reduce `self` and `constness` to two possible combined states instead of four.
252 pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
253 match (constness, self) {
254 (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
256 *this = BoundConstness::NotConst;
257 hir::Constness::NotConst
263 impl fmt::Display for BoundConstness {
264 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
266 Self::NotConst => f.write_str("normal"),
267 Self::ConstIfConst => f.write_str("`~const`"),
284 pub struct ClosureSizeProfileData<'tcx> {
285 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
286 pub before_feature_tys: Ty<'tcx>,
287 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
288 pub after_feature_tys: Ty<'tcx>,
291 pub trait DefIdTree: Copy {
292 fn opt_parent(self, id: DefId) -> Option<DefId>;
296 fn parent(self, id: DefId) -> DefId {
297 match self.opt_parent(id) {
299 // not `unwrap_or_else` to avoid breaking caller tracking
300 None => bug!("{id:?} doesn't have a parent"),
306 fn opt_local_parent(self, id: LocalDefId) -> Option<LocalDefId> {
307 self.opt_parent(id.to_def_id()).map(DefId::expect_local)
312 fn local_parent(self, id: LocalDefId) -> LocalDefId {
313 self.parent(id.to_def_id()).expect_local()
316 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
317 if descendant.krate != ancestor.krate {
321 while descendant != ancestor {
322 match self.opt_parent(descendant) {
323 Some(parent) => descendant = parent,
324 None => return false,
331 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
333 fn opt_parent(self, id: DefId) -> Option<DefId> {
334 self.def_key(id).parent.map(|index| DefId { index, ..id })
339 /// Returns `true` if an item with this visibility is accessible from the given block.
340 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
341 let restriction = match self {
342 // Public items are visible everywhere.
343 Visibility::Public => return true,
344 // Private items from other crates are visible nowhere.
345 Visibility::Invisible => return false,
346 // Restricted items are visible in an arbitrary local module.
347 Visibility::Restricted(other) if other.krate != module.krate => return false,
348 Visibility::Restricted(module) => module,
351 tree.is_descendant_of(module, restriction)
354 /// Returns `true` if this visibility is at least as accessible as the given visibility
355 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
356 let vis_restriction = match vis {
357 Visibility::Public => return self == Visibility::Public,
358 Visibility::Invisible => return true,
359 Visibility::Restricted(module) => module,
362 self.is_accessible_from(vis_restriction, tree)
365 // Returns `true` if this item is visible anywhere in the local crate.
366 pub fn is_visible_locally(self) -> bool {
368 Visibility::Public => true,
369 Visibility::Restricted(def_id) => def_id.is_local(),
370 Visibility::Invisible => false,
374 pub fn is_public(self) -> bool {
375 matches!(self, Visibility::Public)
379 /// The crate variances map is computed during typeck and contains the
380 /// variance of every item in the local crate. You should not use it
381 /// directly, because to do so will make your pass dependent on the
382 /// HIR of every item in the local crate. Instead, use
383 /// `tcx.variances_of()` to get the variance for a *particular*
385 #[derive(HashStable, Debug)]
386 pub struct CrateVariancesMap<'tcx> {
387 /// For each item with generics, maps to a vector of the variance
388 /// of its generics. If an item has no generics, it will have no
390 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
393 // Contains information needed to resolve types and (in the future) look up
394 // the types of AST nodes.
395 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
396 pub struct CReaderCacheKey {
397 pub cnum: Option<CrateNum>,
401 /// Represents a type.
404 /// - This is a very "dumb" struct (with no derives and no `impls`).
405 /// - Values of this type are always interned and thus unique, and are stored
406 /// as an `Interned<TyS>`.
407 /// - `Ty` (which contains a reference to a `Interned<TyS>`) or `Interned<TyS>`
408 /// should be used everywhere instead of `TyS`. In particular, `Ty` has most
409 /// of the relevant methods.
410 #[derive(PartialEq, Eq, PartialOrd, Ord)]
411 #[allow(rustc::usage_of_ty_tykind)]
412 crate struct TyS<'tcx> {
413 /// This field shouldn't be used directly and may be removed in the future.
414 /// Use `Ty::kind()` instead.
417 /// This field provides fast access to information that is also contained
420 /// This field shouldn't be used directly and may be removed in the future.
421 /// Use `Ty::flags()` instead.
424 /// This field provides fast access to information that is also contained
427 /// This is a kind of confusing thing: it stores the smallest
430 /// (a) the binder itself captures nothing but
431 /// (b) all the late-bound things within the type are captured
432 /// by some sub-binder.
434 /// So, for a type without any late-bound things, like `u32`, this
435 /// will be *innermost*, because that is the innermost binder that
436 /// captures nothing. But for a type `&'D u32`, where `'D` is a
437 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
438 /// -- the binder itself does not capture `D`, but `D` is captured
439 /// by an inner binder.
441 /// We call this concept an "exclusive" binder `D` because all
442 /// De Bruijn indices within the type are contained within `0..D`
444 outer_exclusive_binder: ty::DebruijnIndex,
447 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
448 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
449 static_assert_size!(TyS<'_>, 40);
451 // We are actually storing a stable hash cache next to the type, so let's
452 // also check the full size
453 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
454 static_assert_size!(WithStableHash<TyS<'_>>, 56);
456 /// Use this rather than `TyS`, whenever possible.
457 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
458 #[rustc_diagnostic_item = "Ty"]
459 #[rustc_pass_by_value]
460 pub struct Ty<'tcx>(Interned<'tcx, WithStableHash<TyS<'tcx>>>);
462 // Statics only used for internal testing.
463 pub static BOOL_TY: Ty<'static> = Ty(Interned::new_unchecked(&WithStableHash {
465 stable_hash: Fingerprint::ZERO,
467 const BOOL_TYS: TyS<'static> = TyS {
469 flags: TypeFlags::empty(),
470 outer_exclusive_binder: DebruijnIndex::from_usize(0),
473 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
475 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
479 // The other fields just provide fast access to information that is
480 // also contained in `kind`, so no need to hash them.
483 outer_exclusive_binder: _,
486 kind.hash_stable(hcx, hasher)
490 impl ty::EarlyBoundRegion {
491 /// Does this early bound region have a name? Early bound regions normally
492 /// always have names except when using anonymous lifetimes (`'_`).
493 pub fn has_name(&self) -> bool {
494 self.name != kw::UnderscoreLifetime
498 /// Represents a predicate.
500 /// See comments on `TyS`, which apply here too (albeit for
501 /// `PredicateS`/`Predicate` rather than `TyS`/`Ty`).
503 crate struct PredicateS<'tcx> {
504 kind: Binder<'tcx, PredicateKind<'tcx>>,
506 /// See the comment for the corresponding field of [TyS].
507 outer_exclusive_binder: ty::DebruijnIndex,
510 // This type is used a lot. Make sure it doesn't unintentionally get bigger.
511 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
512 static_assert_size!(PredicateS<'_>, 56);
514 /// Use this rather than `PredicateS`, whenever possible.
515 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
516 #[rustc_pass_by_value]
517 pub struct Predicate<'tcx>(Interned<'tcx, PredicateS<'tcx>>);
519 impl<'tcx> Predicate<'tcx> {
520 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
522 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
527 pub fn flags(self) -> TypeFlags {
532 pub fn outer_exclusive_binder(self) -> DebruijnIndex {
533 self.0.outer_exclusive_binder
536 /// Flips the polarity of a Predicate.
538 /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
539 pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
542 .map_bound(|kind| match kind {
543 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
544 Some(PredicateKind::Trait(TraitPredicate {
547 polarity: polarity.flip()?,
555 Some(tcx.mk_predicate(kind))
559 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
560 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
564 // The other fields just provide fast access to information that is
565 // also contained in `kind`, so no need to hash them.
567 outer_exclusive_binder: _,
570 kind.hash_stable(hcx, hasher);
574 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
575 #[derive(HashStable, TypeFoldable)]
576 pub enum PredicateKind<'tcx> {
577 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
578 /// the `Self` type of the trait reference and `A`, `B`, and `C`
579 /// would be the type parameters.
580 Trait(TraitPredicate<'tcx>),
583 RegionOutlives(RegionOutlivesPredicate<'tcx>),
586 TypeOutlives(TypeOutlivesPredicate<'tcx>),
588 /// `where <T as TraitRef>::Name == X`, approximately.
589 /// See the `ProjectionPredicate` struct for details.
590 Projection(ProjectionPredicate<'tcx>),
592 /// No syntax: `T` well-formed.
593 WellFormed(GenericArg<'tcx>),
595 /// Trait must be object-safe.
598 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
599 /// for some substitutions `...` and `T` being a closure type.
600 /// Satisfied (or refuted) once we know the closure's kind.
601 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
605 /// This obligation is created most often when we have two
606 /// unresolved type variables and hence don't have enough
607 /// information to process the subtyping obligation yet.
608 Subtype(SubtypePredicate<'tcx>),
610 /// `T1` coerced to `T2`
612 /// Like a subtyping obligation, this is created most often
613 /// when we have two unresolved type variables and hence
614 /// don't have enough information to process the coercion
615 /// obligation yet. At the moment, we actually process coercions
616 /// very much like subtyping and don't handle the full coercion
618 Coerce(CoercePredicate<'tcx>),
620 /// Constant initializer must evaluate successfully.
621 ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
623 /// Constants must be equal. The first component is the const that is expected.
624 ConstEquate(Const<'tcx>, Const<'tcx>),
626 /// Represents a type found in the environment that we can use for implied bounds.
628 /// Only used for Chalk.
629 TypeWellFormedFromEnv(Ty<'tcx>),
632 /// The crate outlives map is computed during typeck and contains the
633 /// outlives of every item in the local crate. You should not use it
634 /// directly, because to do so will make your pass dependent on the
635 /// HIR of every item in the local crate. Instead, use
636 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
638 #[derive(HashStable, Debug)]
639 pub struct CratePredicatesMap<'tcx> {
640 /// For each struct with outlive bounds, maps to a vector of the
641 /// predicate of its outlive bounds. If an item has no outlives
642 /// bounds, it will have no entry.
643 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
646 impl<'tcx> Predicate<'tcx> {
647 /// Performs a substitution suitable for going from a
648 /// poly-trait-ref to supertraits that must hold if that
649 /// poly-trait-ref holds. This is slightly different from a normal
650 /// substitution in terms of what happens with bound regions. See
651 /// lengthy comment below for details.
652 pub fn subst_supertrait(
655 trait_ref: &ty::PolyTraitRef<'tcx>,
656 ) -> Predicate<'tcx> {
657 // The interaction between HRTB and supertraits is not entirely
658 // obvious. Let me walk you (and myself) through an example.
660 // Let's start with an easy case. Consider two traits:
662 // trait Foo<'a>: Bar<'a,'a> { }
663 // trait Bar<'b,'c> { }
665 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
666 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
667 // knew that `Foo<'x>` (for any 'x) then we also know that
668 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
669 // normal substitution.
671 // In terms of why this is sound, the idea is that whenever there
672 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
673 // holds. So if there is an impl of `T:Foo<'a>` that applies to
674 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
677 // Another example to be careful of is this:
679 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
680 // trait Bar1<'b,'c> { }
682 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
683 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
684 // reason is similar to the previous example: any impl of
685 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
686 // basically we would want to collapse the bound lifetimes from
687 // the input (`trait_ref`) and the supertraits.
689 // To achieve this in practice is fairly straightforward. Let's
690 // consider the more complicated scenario:
692 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
693 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
694 // where both `'x` and `'b` would have a DB index of 1.
695 // The substitution from the input trait-ref is therefore going to be
696 // `'a => 'x` (where `'x` has a DB index of 1).
697 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
698 // early-bound parameter and `'b' is a late-bound parameter with a
700 // - If we replace `'a` with `'x` from the input, it too will have
701 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
702 // just as we wanted.
704 // There is only one catch. If we just apply the substitution `'a
705 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
706 // adjust the DB index because we substituting into a binder (it
707 // tries to be so smart...) resulting in `for<'x> for<'b>
708 // Bar1<'x,'b>` (we have no syntax for this, so use your
709 // imagination). Basically the 'x will have DB index of 2 and 'b
710 // will have DB index of 1. Not quite what we want. So we apply
711 // the substitution to the *contents* of the trait reference,
712 // rather than the trait reference itself (put another way, the
713 // substitution code expects equal binding levels in the values
714 // from the substitution and the value being substituted into, and
715 // this trick achieves that).
717 // Working through the second example:
718 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
719 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
720 // We want to end up with:
721 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
723 // 1) We must shift all bound vars in predicate by the length
724 // of trait ref's bound vars. So, we would end up with predicate like
725 // Self: Bar1<'a, '^0.1>
726 // 2) We can then apply the trait substs to this, ending up with
727 // T: Bar1<'^0.0, '^0.1>
728 // 3) Finally, to create the final bound vars, we concatenate the bound
729 // vars of the trait ref with those of the predicate:
731 let bound_pred = self.kind();
732 let pred_bound_vars = bound_pred.bound_vars();
733 let trait_bound_vars = trait_ref.bound_vars();
734 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
736 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
737 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
738 let new = EarlyBinder(shifted_pred).subst(tcx, trait_ref.skip_binder().substs);
739 // 3) ['x] + ['b] -> ['x, 'b]
741 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
742 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
746 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
747 #[derive(HashStable, TypeFoldable)]
748 pub struct TraitPredicate<'tcx> {
749 pub trait_ref: TraitRef<'tcx>,
751 pub constness: BoundConstness,
753 /// If polarity is Positive: we are proving that the trait is implemented.
755 /// If polarity is Negative: we are proving that a negative impl of this trait
756 /// exists. (Note that coherence also checks whether negative impls of supertraits
757 /// exist via a series of predicates.)
759 /// If polarity is Reserved: that's a bug.
760 pub polarity: ImplPolarity,
763 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
765 impl<'tcx> TraitPredicate<'tcx> {
766 pub fn remap_constness(&mut self, tcx: TyCtxt<'tcx>, param_env: &mut ParamEnv<'tcx>) {
767 if unlikely!(Some(self.trait_ref.def_id) == tcx.lang_items().drop_trait()) {
768 // remap without changing constness of this predicate.
769 // this is because `T: ~const Drop` has a different meaning to `T: Drop`
770 // FIXME(fee1-dead): remove this logic after beta bump
771 param_env.remap_constness_with(self.constness)
773 *param_env = param_env.with_constness(self.constness.and(param_env.constness()))
777 /// Remap the constness of this predicate before emitting it for diagnostics.
778 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
779 // this is different to `remap_constness` that callees want to print this predicate
780 // in case of selection errors. `T: ~const Drop` bounds cannot end up here when the
781 // param_env is not const because we it is always satisfied in non-const contexts.
782 if let hir::Constness::NotConst = param_env.constness() {
783 self.constness = ty::BoundConstness::NotConst;
787 pub fn def_id(self) -> DefId {
788 self.trait_ref.def_id
791 pub fn self_ty(self) -> Ty<'tcx> {
792 self.trait_ref.self_ty()
796 pub fn is_const_if_const(self) -> bool {
797 self.constness == BoundConstness::ConstIfConst
801 impl<'tcx> PolyTraitPredicate<'tcx> {
802 pub fn def_id(self) -> DefId {
803 // Ok to skip binder since trait `DefId` does not care about regions.
804 self.skip_binder().def_id()
807 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
808 self.map_bound(|trait_ref| trait_ref.self_ty())
811 /// Remap the constness of this predicate before emitting it for diagnostics.
812 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
813 *self = self.map_bound(|mut p| {
814 p.remap_constness_diag(param_env);
820 pub fn is_const_if_const(self) -> bool {
821 self.skip_binder().is_const_if_const()
825 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
826 #[derive(HashStable, TypeFoldable)]
827 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
828 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
829 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
830 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
831 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
833 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
834 /// whether the `a` type is the type that we should label as "expected" when
835 /// presenting user diagnostics.
836 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
837 #[derive(HashStable, TypeFoldable)]
838 pub struct SubtypePredicate<'tcx> {
839 pub a_is_expected: bool,
843 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
845 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
846 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
847 #[derive(HashStable, TypeFoldable)]
848 pub struct CoercePredicate<'tcx> {
852 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
854 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)]
855 #[derive(HashStable, TypeFoldable)]
856 pub enum Term<'tcx> {
861 impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
862 fn from(ty: Ty<'tcx>) -> Self {
867 impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
868 fn from(c: Const<'tcx>) -> Self {
873 impl<'tcx> Term<'tcx> {
874 pub fn ty(&self) -> Option<Ty<'tcx>> {
875 if let Term::Ty(ty) = self { Some(*ty) } else { None }
877 pub fn ct(&self) -> Option<Const<'tcx>> {
878 if let Term::Const(c) = self { Some(*c) } else { None }
882 /// This kind of predicate has no *direct* correspondent in the
883 /// syntax, but it roughly corresponds to the syntactic forms:
885 /// 1. `T: TraitRef<..., Item = Type>`
886 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
888 /// In particular, form #1 is "desugared" to the combination of a
889 /// normal trait predicate (`T: TraitRef<...>`) and one of these
890 /// predicates. Form #2 is a broader form in that it also permits
891 /// equality between arbitrary types. Processing an instance of
892 /// Form #2 eventually yields one of these `ProjectionPredicate`
893 /// instances to normalize the LHS.
894 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
895 #[derive(HashStable, TypeFoldable)]
896 pub struct ProjectionPredicate<'tcx> {
897 pub projection_ty: ProjectionTy<'tcx>,
898 pub term: Term<'tcx>,
901 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
903 impl<'tcx> PolyProjectionPredicate<'tcx> {
904 /// Returns the `DefId` of the trait of the associated item being projected.
906 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
907 self.skip_binder().projection_ty.trait_def_id(tcx)
910 /// Get the [PolyTraitRef] required for this projection to be well formed.
911 /// Note that for generic associated types the predicates of the associated
912 /// type also need to be checked.
914 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
915 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
916 // `self.0.trait_ref` is permitted to have escaping regions.
917 // This is because here `self` has a `Binder` and so does our
918 // return value, so we are preserving the number of binding
920 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
923 pub fn term(&self) -> Binder<'tcx, Term<'tcx>> {
924 self.map_bound(|predicate| predicate.term)
927 /// The `DefId` of the `TraitItem` for the associated type.
929 /// Note that this is not the `DefId` of the `TraitRef` containing this
930 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
931 pub fn projection_def_id(&self) -> DefId {
932 // Ok to skip binder since trait `DefId` does not care about regions.
933 self.skip_binder().projection_ty.item_def_id
937 pub trait ToPolyTraitRef<'tcx> {
938 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
941 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
942 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
943 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
947 pub trait ToPredicate<'tcx> {
948 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
951 impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
953 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
954 tcx.mk_predicate(self)
958 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
959 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
960 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
964 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
965 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
966 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
970 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
971 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
972 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
976 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
977 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
978 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
982 impl<'tcx> Predicate<'tcx> {
983 pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
984 let predicate = self.kind();
985 match predicate.skip_binder() {
986 PredicateKind::Trait(t) => Some(predicate.rebind(t)),
987 PredicateKind::Projection(..)
988 | PredicateKind::Subtype(..)
989 | PredicateKind::Coerce(..)
990 | PredicateKind::RegionOutlives(..)
991 | PredicateKind::WellFormed(..)
992 | PredicateKind::ObjectSafe(..)
993 | PredicateKind::ClosureKind(..)
994 | PredicateKind::TypeOutlives(..)
995 | PredicateKind::ConstEvaluatable(..)
996 | PredicateKind::ConstEquate(..)
997 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1001 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1002 let predicate = self.kind();
1003 match predicate.skip_binder() {
1004 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
1005 PredicateKind::Trait(..)
1006 | PredicateKind::Projection(..)
1007 | PredicateKind::Subtype(..)
1008 | PredicateKind::Coerce(..)
1009 | PredicateKind::RegionOutlives(..)
1010 | PredicateKind::WellFormed(..)
1011 | PredicateKind::ObjectSafe(..)
1012 | PredicateKind::ClosureKind(..)
1013 | PredicateKind::ConstEvaluatable(..)
1014 | PredicateKind::ConstEquate(..)
1015 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1020 /// Represents the bounds declared on a particular set of type
1021 /// parameters. Should eventually be generalized into a flag list of
1022 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
1023 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1024 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1025 /// the `GenericPredicates` are expressed in terms of the bound type
1026 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1027 /// represented a set of bounds for some particular instantiation,
1028 /// meaning that the generic parameters have been substituted with
1032 /// ```ignore (illustrative)
1033 /// struct Foo<T, U: Bar<T>> { ... }
1035 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1036 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1037 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1038 /// [usize:Bar<isize>]]`.
1039 #[derive(Clone, Debug, TypeFoldable)]
1040 pub struct InstantiatedPredicates<'tcx> {
1041 pub predicates: Vec<Predicate<'tcx>>,
1042 pub spans: Vec<Span>,
1045 impl<'tcx> InstantiatedPredicates<'tcx> {
1046 pub fn empty() -> InstantiatedPredicates<'tcx> {
1047 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1050 pub fn is_empty(&self) -> bool {
1051 self.predicates.is_empty()
1067 pub struct OpaqueTypeKey<'tcx> {
1069 pub substs: SubstsRef<'tcx>,
1072 #[derive(Copy, Clone, Debug, TypeFoldable, HashStable, TyEncodable, TyDecodable)]
1073 pub struct OpaqueHiddenType<'tcx> {
1074 /// The span of this particular definition of the opaque type. So
1077 /// ```ignore (incomplete snippet)
1078 /// type Foo = impl Baz;
1079 /// fn bar() -> Foo {
1080 /// // ^^^ This is the span we are looking for!
1084 /// In cases where the fn returns `(impl Trait, impl Trait)` or
1085 /// other such combinations, the result is currently
1086 /// over-approximated, but better than nothing.
1089 /// The type variable that represents the value of the opaque type
1090 /// that we require. In other words, after we compile this function,
1091 /// we will be created a constraint like:
1092 /// ```ignore (pseudo-rust)
1095 /// where `?C` is the value of this type variable. =) It may
1096 /// naturally refer to the type and lifetime parameters in scope
1097 /// in this function, though ultimately it should only reference
1098 /// those that are arguments to `Foo` in the constraint above. (In
1099 /// other words, `?C` should not include `'b`, even though it's a
1100 /// lifetime parameter on `foo`.)
1104 impl<'tcx> OpaqueHiddenType<'tcx> {
1105 pub fn report_mismatch(&self, other: &Self, tcx: TyCtxt<'tcx>) {
1106 // Found different concrete types for the opaque type.
1107 let mut err = tcx.sess.struct_span_err(
1109 "concrete type differs from previous defining opaque type use",
1111 err.span_label(other.span, format!("expected `{}`, got `{}`", self.ty, other.ty));
1112 if self.span == other.span {
1115 "this expression supplies two conflicting concrete types for the same opaque type",
1118 err.span_note(self.span, "previous use here");
1124 rustc_index::newtype_index! {
1125 /// "Universes" are used during type- and trait-checking in the
1126 /// presence of `for<..>` binders to control what sets of names are
1127 /// visible. Universes are arranged into a tree: the root universe
1128 /// contains names that are always visible. Each child then adds a new
1129 /// set of names that are visible, in addition to those of its parent.
1130 /// We say that the child universe "extends" the parent universe with
1133 /// To make this more concrete, consider this program:
1135 /// ```ignore (illustrative)
1137 /// fn bar<T>(x: T) {
1138 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1142 /// The struct name `Foo` is in the root universe U0. But the type
1143 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1144 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1145 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1146 /// region `'a` is in a universe U2 that extends U1, because we can
1147 /// name it inside the fn type but not outside.
1149 /// Universes are used to do type- and trait-checking around these
1150 /// "forall" binders (also called **universal quantification**). The
1151 /// idea is that when, in the body of `bar`, we refer to `T` as a
1152 /// type, we aren't referring to any type in particular, but rather a
1153 /// kind of "fresh" type that is distinct from all other types we have
1154 /// actually declared. This is called a **placeholder** type, and we
1155 /// use universes to talk about this. In other words, a type name in
1156 /// universe 0 always corresponds to some "ground" type that the user
1157 /// declared, but a type name in a non-zero universe is a placeholder
1158 /// type -- an idealized representative of "types in general" that we
1159 /// use for checking generic functions.
1160 pub struct UniverseIndex {
1162 DEBUG_FORMAT = "U{}",
1166 impl UniverseIndex {
1167 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1169 /// Returns the "next" universe index in order -- this new index
1170 /// is considered to extend all previous universes. This
1171 /// corresponds to entering a `forall` quantifier. So, for
1172 /// example, suppose we have this type in universe `U`:
1174 /// ```ignore (illustrative)
1175 /// for<'a> fn(&'a u32)
1178 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1179 /// new universe that extends `U` -- in this new universe, we can
1180 /// name the region `'a`, but that region was not nameable from
1181 /// `U` because it was not in scope there.
1182 pub fn next_universe(self) -> UniverseIndex {
1183 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1186 /// Returns `true` if `self` can name a name from `other` -- in other words,
1187 /// if the set of names in `self` is a superset of those in
1188 /// `other` (`self >= other`).
1189 pub fn can_name(self, other: UniverseIndex) -> bool {
1190 self.private >= other.private
1193 /// Returns `true` if `self` cannot name some names from `other` -- in other
1194 /// words, if the set of names in `self` is a strict subset of
1195 /// those in `other` (`self < other`).
1196 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1197 self.private < other.private
1201 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1202 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1203 /// regions/types/consts within the same universe simply have an unknown relationship to one
1205 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1206 pub struct Placeholder<T> {
1207 pub universe: UniverseIndex,
1211 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1213 T: HashStable<StableHashingContext<'a>>,
1215 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1216 self.universe.hash_stable(hcx, hasher);
1217 self.name.hash_stable(hcx, hasher);
1221 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1223 pub type PlaceholderType = Placeholder<BoundVar>;
1225 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1226 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1227 pub struct BoundConst<'tcx> {
1232 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1234 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1235 /// the `DefId` of the generic parameter it instantiates.
1237 /// This is used to avoid calls to `type_of` for const arguments during typeck
1238 /// which cause cycle errors.
1243 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1244 /// // ^ const parameter
1248 /// fn foo<const M: u8>(&self) -> usize { 42 }
1249 /// // ^ const parameter
1254 /// let _b = a.foo::<{ 3 + 7 }>();
1255 /// // ^^^^^^^^^ const argument
1259 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1260 /// which `foo` is used until we know the type of `a`.
1262 /// We only know the type of `a` once we are inside of `typeck(main)`.
1263 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1264 /// requires us to evaluate the const argument.
1266 /// To evaluate that const argument we need to know its type,
1267 /// which we would get using `type_of(const_arg)`. This requires us to
1268 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1269 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1270 /// which results in a cycle.
1272 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1274 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1275 /// already resolved `foo` so we know which const parameter this argument instantiates.
1276 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1277 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1278 /// trivial to compute.
1280 /// If we now want to use that constant in a place which potentially needs its type
1281 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1282 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1283 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1284 /// to get the type of `did`.
1285 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1286 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1287 #[derive(Hash, HashStable)]
1288 pub struct WithOptConstParam<T> {
1290 /// The `DefId` of the corresponding generic parameter in case `did` is
1291 /// a const argument.
1293 /// Note that even if `did` is a const argument, this may still be `None`.
1294 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1295 /// to potentially update `param_did` in the case it is `None`.
1296 pub const_param_did: Option<DefId>,
1299 impl<T> WithOptConstParam<T> {
1300 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1302 pub fn unknown(did: T) -> WithOptConstParam<T> {
1303 WithOptConstParam { did, const_param_did: None }
1307 impl WithOptConstParam<LocalDefId> {
1308 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1309 /// `None` otherwise.
1311 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1312 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1315 /// In case `self` is unknown but `self.did` is a const argument, this returns
1316 /// a `WithOptConstParam` with the correct `const_param_did`.
1318 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1319 if self.const_param_did.is_none() {
1320 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1321 return Some(WithOptConstParam { did: self.did, const_param_did });
1328 pub fn to_global(self) -> WithOptConstParam<DefId> {
1329 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1332 pub fn def_id_for_type_of(self) -> DefId {
1333 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1337 impl WithOptConstParam<DefId> {
1338 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1341 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1344 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1345 if let Some(param_did) = self.const_param_did {
1346 if let Some(did) = self.did.as_local() {
1347 return Some((did, param_did));
1354 pub fn is_local(self) -> bool {
1358 pub fn def_id_for_type_of(self) -> DefId {
1359 self.const_param_did.unwrap_or(self.did)
1363 /// When type checking, we use the `ParamEnv` to track
1364 /// details about the set of where-clauses that are in scope at this
1365 /// particular point.
1366 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1367 pub struct ParamEnv<'tcx> {
1368 /// This packs both caller bounds and the reveal enum into one pointer.
1370 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1371 /// basically the set of bounds on the in-scope type parameters, translated
1372 /// into `Obligation`s, and elaborated and normalized.
1374 /// Use the `caller_bounds()` method to access.
1376 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1377 /// want `Reveal::All`.
1379 /// Note: This is packed, use the reveal() method to access it.
1380 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
1383 #[derive(Copy, Clone)]
1385 reveal: traits::Reveal,
1386 constness: hir::Constness,
1389 unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
1390 const BITS: usize = 2;
1392 fn into_usize(self) -> usize {
1394 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
1395 Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
1396 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
1397 Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
1401 unsafe fn from_usize(ptr: usize) -> Self {
1403 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1404 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
1405 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
1406 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
1407 _ => std::hint::unreachable_unchecked(),
1412 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1413 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1414 f.debug_struct("ParamEnv")
1415 .field("caller_bounds", &self.caller_bounds())
1416 .field("reveal", &self.reveal())
1417 .field("constness", &self.constness())
1422 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1423 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1424 self.caller_bounds().hash_stable(hcx, hasher);
1425 self.reveal().hash_stable(hcx, hasher);
1426 self.constness().hash_stable(hcx, hasher);
1430 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1431 fn try_super_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
1434 ) -> Result<Self, F::Error> {
1436 self.caller_bounds().try_fold_with(folder)?,
1437 self.reveal().try_fold_with(folder)?,
1438 self.constness().try_fold_with(folder)?,
1442 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1443 self.caller_bounds().visit_with(visitor)?;
1444 self.reveal().visit_with(visitor)?;
1445 self.constness().visit_with(visitor)
1449 impl<'tcx> ParamEnv<'tcx> {
1450 /// Construct a trait environment suitable for contexts where
1451 /// there are no where-clauses in scope. Hidden types (like `impl
1452 /// Trait`) are left hidden, so this is suitable for ordinary
1455 pub fn empty() -> Self {
1456 Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
1460 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1461 self.packed.pointer()
1465 pub fn reveal(self) -> traits::Reveal {
1466 self.packed.tag().reveal
1470 pub fn constness(self) -> hir::Constness {
1471 self.packed.tag().constness
1475 pub fn is_const(self) -> bool {
1476 self.packed.tag().constness == hir::Constness::Const
1479 /// Construct a trait environment with no where-clauses in scope
1480 /// where the values of all `impl Trait` and other hidden types
1481 /// are revealed. This is suitable for monomorphized, post-typeck
1482 /// environments like codegen or doing optimizations.
1484 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1485 /// or invoke `param_env.with_reveal_all()`.
1487 pub fn reveal_all() -> Self {
1488 Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
1491 /// Construct a trait environment with the given set of predicates.
1494 caller_bounds: &'tcx List<Predicate<'tcx>>,
1496 constness: hir::Constness,
1498 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
1501 pub fn with_user_facing(mut self) -> Self {
1502 self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
1507 pub fn with_constness(mut self, constness: hir::Constness) -> Self {
1508 self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
1513 pub fn with_const(mut self) -> Self {
1514 self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
1519 pub fn without_const(mut self) -> Self {
1520 self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
1525 pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
1526 *self = self.with_constness(constness.and(self.constness()))
1529 /// Returns a new parameter environment with the same clauses, but
1530 /// which "reveals" the true results of projections in all cases
1531 /// (even for associated types that are specializable). This is
1532 /// the desired behavior during codegen and certain other special
1533 /// contexts; normally though we want to use `Reveal::UserFacing`,
1534 /// which is the default.
1535 /// All opaque types in the caller_bounds of the `ParamEnv`
1536 /// will be normalized to their underlying types.
1537 /// See PR #65989 and issue #65918 for more details
1538 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1539 if self.packed.tag().reveal == traits::Reveal::All {
1544 tcx.normalize_opaque_types(self.caller_bounds()),
1550 /// Returns this same environment but with no caller bounds.
1552 pub fn without_caller_bounds(self) -> Self {
1553 Self::new(List::empty(), self.reveal(), self.constness())
1556 /// Creates a suitable environment in which to perform trait
1557 /// queries on the given value. When type-checking, this is simply
1558 /// the pair of the environment plus value. But when reveal is set to
1559 /// All, then if `value` does not reference any type parameters, we will
1560 /// pair it with the empty environment. This improves caching and is generally
1563 /// N.B., we preserve the environment when type-checking because it
1564 /// is possible for the user to have wacky where-clauses like
1565 /// `where Box<u32>: Copy`, which are clearly never
1566 /// satisfiable. We generally want to behave as if they were true,
1567 /// although the surrounding function is never reachable.
1568 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1569 match self.reveal() {
1570 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1573 if value.is_global() {
1574 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1576 ParamEnvAnd { param_env: self, value }
1583 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1584 // the constness of trait bounds is being propagated correctly.
1585 impl<'tcx> PolyTraitRef<'tcx> {
1587 pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
1588 self.map_bound(|trait_ref| ty::TraitPredicate {
1591 polarity: ty::ImplPolarity::Positive,
1596 pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
1597 self.with_constness(BoundConstness::NotConst)
1601 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1602 pub struct ParamEnvAnd<'tcx, T> {
1603 pub param_env: ParamEnv<'tcx>,
1607 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1608 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1609 (self.param_env, self.value)
1613 pub fn without_const(mut self) -> Self {
1614 self.param_env = self.param_env.without_const();
1619 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1621 T: HashStable<StableHashingContext<'a>>,
1623 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1624 let ParamEnvAnd { ref param_env, ref value } = *self;
1626 param_env.hash_stable(hcx, hasher);
1627 value.hash_stable(hcx, hasher);
1631 #[derive(Copy, Clone, Debug, HashStable)]
1632 pub struct Destructor {
1633 /// The `DefId` of the destructor method
1635 /// The constness of the destructor method
1636 pub constness: hir::Constness,
1640 #[derive(HashStable, TyEncodable, TyDecodable)]
1641 pub struct VariantFlags: u32 {
1642 const NO_VARIANT_FLAGS = 0;
1643 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1644 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1645 /// Indicates whether this variant was obtained as part of recovering from
1646 /// a syntactic error. May be incomplete or bogus.
1647 const IS_RECOVERED = 1 << 1;
1651 /// Definition of a variant -- a struct's fields or an enum variant.
1652 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1653 pub struct VariantDef {
1654 /// `DefId` that identifies the variant itself.
1655 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1657 /// `DefId` that identifies the variant's constructor.
1658 /// If this variant is a struct variant, then this is `None`.
1659 pub ctor_def_id: Option<DefId>,
1660 /// Variant or struct name.
1662 /// Discriminant of this variant.
1663 pub discr: VariantDiscr,
1664 /// Fields of this variant.
1665 pub fields: Vec<FieldDef>,
1666 /// Type of constructor of variant.
1667 pub ctor_kind: CtorKind,
1668 /// Flags of the variant (e.g. is field list non-exhaustive)?
1669 flags: VariantFlags,
1673 /// Creates a new `VariantDef`.
1675 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1676 /// represents an enum variant).
1678 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1679 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1681 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1682 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1683 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1684 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1685 /// built-in trait), and we do not want to load attributes twice.
1687 /// If someone speeds up attribute loading to not be a performance concern, they can
1688 /// remove this hack and use the constructor `DefId` everywhere.
1691 variant_did: Option<DefId>,
1692 ctor_def_id: Option<DefId>,
1693 discr: VariantDiscr,
1694 fields: Vec<FieldDef>,
1695 ctor_kind: CtorKind,
1699 is_field_list_non_exhaustive: bool,
1702 "VariantDef::new(name = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1703 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1704 name, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1707 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1708 if is_field_list_non_exhaustive {
1709 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1713 flags |= VariantFlags::IS_RECOVERED;
1717 def_id: variant_did.unwrap_or(parent_did),
1727 /// Is this field list non-exhaustive?
1729 pub fn is_field_list_non_exhaustive(&self) -> bool {
1730 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1733 /// Was this variant obtained as part of recovering from a syntactic error?
1735 pub fn is_recovered(&self) -> bool {
1736 self.flags.intersects(VariantFlags::IS_RECOVERED)
1739 /// Computes the `Ident` of this variant by looking up the `Span`
1740 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1741 Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1745 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1746 pub enum VariantDiscr {
1747 /// Explicit value for this variant, i.e., `X = 123`.
1748 /// The `DefId` corresponds to the embedded constant.
1751 /// The previous variant's discriminant plus one.
1752 /// For efficiency reasons, the distance from the
1753 /// last `Explicit` discriminant is being stored,
1754 /// or `0` for the first variant, if it has none.
1758 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1759 pub struct FieldDef {
1762 pub vis: Visibility,
1766 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1767 pub struct ReprFlags: u8 {
1768 const IS_C = 1 << 0;
1769 const IS_SIMD = 1 << 1;
1770 const IS_TRANSPARENT = 1 << 2;
1771 // Internal only for now. If true, don't reorder fields.
1772 const IS_LINEAR = 1 << 3;
1773 // If true, don't expose any niche to type's context.
1774 const HIDE_NICHE = 1 << 4;
1775 // If true, the type's layout can be randomized using
1776 // the seed stored in `ReprOptions.layout_seed`
1777 const RANDOMIZE_LAYOUT = 1 << 5;
1778 // Any of these flags being set prevent field reordering optimisation.
1779 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
1780 | ReprFlags::IS_SIMD.bits
1781 | ReprFlags::IS_LINEAR.bits;
1785 /// Represents the repr options provided by the user,
1786 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
1787 pub struct ReprOptions {
1788 pub int: Option<attr::IntType>,
1789 pub align: Option<Align>,
1790 pub pack: Option<Align>,
1791 pub flags: ReprFlags,
1792 /// The seed to be used for randomizing a type's layout
1794 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
1795 /// be the "most accurate" hash as it'd encompass the item and crate
1796 /// hash without loss, but it does pay the price of being larger.
1797 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
1798 /// purposes (primarily `-Z randomize-layout`)
1799 pub field_shuffle_seed: u64,
1803 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1804 let mut flags = ReprFlags::empty();
1805 let mut size = None;
1806 let mut max_align: Option<Align> = None;
1807 let mut min_pack: Option<Align> = None;
1809 // Generate a deterministically-derived seed from the item's path hash
1810 // to allow for cross-crate compilation to actually work
1811 let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
1813 // If the user defined a custom seed for layout randomization, xor the item's
1814 // path hash with the user defined seed, this will allowing determinism while
1815 // still allowing users to further randomize layout generation for e.g. fuzzing
1816 if let Some(user_seed) = tcx.sess.opts.debugging_opts.layout_seed {
1817 field_shuffle_seed ^= user_seed;
1820 for attr in tcx.get_attrs(did, sym::repr) {
1821 for r in attr::parse_repr_attr(&tcx.sess, attr) {
1822 flags.insert(match r {
1823 attr::ReprC => ReprFlags::IS_C,
1824 attr::ReprPacked(pack) => {
1825 let pack = Align::from_bytes(pack as u64).unwrap();
1826 min_pack = Some(if let Some(min_pack) = min_pack {
1833 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1834 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
1835 attr::ReprSimd => ReprFlags::IS_SIMD,
1836 attr::ReprInt(i) => {
1840 attr::ReprAlign(align) => {
1841 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
1848 // If `-Z randomize-layout` was enabled for the type definition then we can
1849 // consider performing layout randomization
1850 if tcx.sess.opts.debugging_opts.randomize_layout {
1851 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1854 // This is here instead of layout because the choice must make it into metadata.
1855 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
1856 flags.insert(ReprFlags::IS_LINEAR);
1859 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1863 pub fn simd(&self) -> bool {
1864 self.flags.contains(ReprFlags::IS_SIMD)
1868 pub fn c(&self) -> bool {
1869 self.flags.contains(ReprFlags::IS_C)
1873 pub fn packed(&self) -> bool {
1878 pub fn transparent(&self) -> bool {
1879 self.flags.contains(ReprFlags::IS_TRANSPARENT)
1883 pub fn linear(&self) -> bool {
1884 self.flags.contains(ReprFlags::IS_LINEAR)
1888 pub fn hide_niche(&self) -> bool {
1889 self.flags.contains(ReprFlags::HIDE_NICHE)
1892 /// Returns the discriminant type, given these `repr` options.
1893 /// This must only be called on enums!
1894 pub fn discr_type(&self) -> attr::IntType {
1895 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1898 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
1899 /// layout" optimizations, such as representing `Foo<&T>` as a
1901 pub fn inhibit_enum_layout_opt(&self) -> bool {
1902 self.c() || self.int.is_some()
1905 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
1906 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
1907 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
1908 if let Some(pack) = self.pack {
1909 if pack.bytes() == 1 {
1914 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
1917 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
1918 /// was enabled for its declaration crate
1919 pub fn can_randomize_type_layout(&self) -> bool {
1920 !self.inhibit_struct_field_reordering_opt()
1921 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
1924 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
1925 pub fn inhibit_union_abi_opt(&self) -> bool {
1930 impl<'tcx> FieldDef {
1931 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
1932 /// typically obtained via the second field of [`TyKind::Adt`].
1933 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
1934 tcx.bound_type_of(self.did).subst(tcx, subst)
1937 /// Computes the `Ident` of this variant by looking up the `Span`
1938 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1939 Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
1943 pub type Attributes<'tcx> = impl Iterator<Item = &'tcx ast::Attribute>;
1944 #[derive(Debug, PartialEq, Eq)]
1945 pub enum ImplOverlapKind {
1946 /// These impls are always allowed to overlap.
1948 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1951 /// These impls are allowed to overlap, but that raises
1952 /// an issue #33140 future-compatibility warning.
1954 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
1955 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
1957 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
1958 /// that difference, making what reduces to the following set of impls:
1960 /// ```compile_fail,(E0119)
1962 /// impl Trait for dyn Send + Sync {}
1963 /// impl Trait for dyn Sync + Send {}
1966 /// Obviously, once we made these types be identical, that code causes a coherence
1967 /// error and a fairly big headache for us. However, luckily for us, the trait
1968 /// `Trait` used in this case is basically a marker trait, and therefore having
1969 /// overlapping impls for it is sound.
1971 /// To handle this, we basically regard the trait as a marker trait, with an additional
1972 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
1973 /// it has the following restrictions:
1975 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
1977 /// 2. The trait-ref of both impls must be equal.
1978 /// 3. The trait-ref of both impls must be a trait object type consisting only of
1980 /// 4. Neither of the impls can have any where-clauses.
1982 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
1986 impl<'tcx> TyCtxt<'tcx> {
1987 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1988 self.typeck(self.hir().body_owner_def_id(body))
1991 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1992 self.associated_items(id)
1993 .in_definition_order()
1994 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
1997 /// Look up the name of a definition across crates. This does not look at HIR.
1998 pub fn opt_item_name(self, def_id: DefId) -> Option<Symbol> {
1999 if let Some(cnum) = def_id.as_crate_root() {
2000 Some(self.crate_name(cnum))
2002 let def_key = self.def_key(def_id);
2003 match def_key.disambiguated_data.data {
2004 // The name of a constructor is that of its parent.
2005 rustc_hir::definitions::DefPathData::Ctor => self
2006 .opt_item_name(DefId { krate: def_id.krate, index: def_key.parent.unwrap() }),
2007 // The name of opaque types only exists in HIR.
2008 rustc_hir::definitions::DefPathData::ImplTrait
2009 if let Some(def_id) = def_id.as_local() =>
2010 self.hir().opt_name(self.hir().local_def_id_to_hir_id(def_id)),
2011 _ => def_key.get_opt_name(),
2016 /// Look up the name of a definition across crates. This does not look at HIR.
2018 /// This method will ICE if the corresponding item does not have a name. In these cases, use
2019 /// [`opt_item_name`] instead.
2021 /// [`opt_item_name`]: Self::opt_item_name
2022 pub fn item_name(self, id: DefId) -> Symbol {
2023 self.opt_item_name(id).unwrap_or_else(|| {
2024 bug!("item_name: no name for {:?}", self.def_path(id));
2028 /// Look up the name and span of a definition.
2030 /// See [`item_name`][Self::item_name] for more information.
2031 pub fn opt_item_ident(self, def_id: DefId) -> Option<Ident> {
2032 let def = self.opt_item_name(def_id)?;
2035 .and_then(|id| self.def_ident_span(id))
2036 .unwrap_or(rustc_span::DUMMY_SP);
2037 Some(Ident::new(def, span))
2040 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2041 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2042 Some(self.associated_item(def_id))
2048 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
2049 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
2052 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2056 .position(|field| self.hygienic_eq(ident, field.ident(self), variant.def_id))
2059 /// Returns `true` if the impls are the same polarity and the trait either
2060 /// has no items or is annotated `#[marker]` and prevents item overrides.
2061 pub fn impls_are_allowed_to_overlap(
2065 ) -> Option<ImplOverlapKind> {
2066 // If either trait impl references an error, they're allowed to overlap,
2067 // as one of them essentially doesn't exist.
2068 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2069 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2071 return Some(ImplOverlapKind::Permitted { marker: false });
2074 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2075 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2076 // `#[rustc_reservation_impl]` impls don't overlap with anything
2078 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2081 return Some(ImplOverlapKind::Permitted { marker: false });
2083 (ImplPolarity::Positive, ImplPolarity::Negative)
2084 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2085 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2087 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2092 (ImplPolarity::Positive, ImplPolarity::Positive)
2093 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2096 let is_marker_overlap = {
2097 let is_marker_impl = |def_id: DefId| -> bool {
2098 let trait_ref = self.impl_trait_ref(def_id);
2099 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2101 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2104 if is_marker_overlap {
2106 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2109 Some(ImplOverlapKind::Permitted { marker: true })
2111 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2112 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2113 if self_ty1 == self_ty2 {
2115 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2118 return Some(ImplOverlapKind::Issue33140);
2121 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2122 def_id1, def_id2, self_ty1, self_ty2
2128 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2133 /// Returns `ty::VariantDef` if `res` refers to a struct,
2134 /// or variant or their constructors, panics otherwise.
2135 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2137 Res::Def(DefKind::Variant, did) => {
2138 let enum_did = self.parent(did);
2139 self.adt_def(enum_did).variant_with_id(did)
2141 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2142 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2143 let variant_did = self.parent(variant_ctor_did);
2144 let enum_did = self.parent(variant_did);
2145 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2147 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2148 let struct_did = self.parent(ctor_did);
2149 self.adt_def(struct_did).non_enum_variant()
2151 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2155 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2156 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2158 ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
2160 | DefKind::Static(..)
2161 | DefKind::AssocConst
2163 | DefKind::AnonConst
2164 | DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
2165 // If the caller wants `mir_for_ctfe` of a function they should not be using
2166 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2168 assert_eq!(def.const_param_did, None);
2169 self.optimized_mir(def.did)
2172 ty::InstanceDef::VtableShim(..)
2173 | ty::InstanceDef::ReifyShim(..)
2174 | ty::InstanceDef::Intrinsic(..)
2175 | ty::InstanceDef::FnPtrShim(..)
2176 | ty::InstanceDef::Virtual(..)
2177 | ty::InstanceDef::ClosureOnceShim { .. }
2178 | ty::InstanceDef::DropGlue(..)
2179 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2183 // FIXME(@lcnr): Remove this function.
2184 pub fn get_attrs_unchecked(self, did: DefId) -> &'tcx [ast::Attribute] {
2185 if let Some(did) = did.as_local() {
2186 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2188 self.item_attrs(did)
2192 /// Gets all attributes with the given name.
2193 pub fn get_attrs(self, did: DefId, attr: Symbol) -> ty::Attributes<'tcx> {
2194 let filter_fn = move |a: &&ast::Attribute| a.has_name(attr);
2195 if let Some(did) = did.as_local() {
2196 self.hir().attrs(self.hir().local_def_id_to_hir_id(did)).iter().filter(filter_fn)
2197 } else if cfg!(debug_assertions) && rustc_feature::is_builtin_only_local(attr) {
2198 bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr);
2200 self.item_attrs(did).iter().filter(filter_fn)
2204 pub fn get_attr(self, did: DefId, attr: Symbol) -> Option<&'tcx ast::Attribute> {
2205 self.get_attrs(did, attr).next()
2208 /// Determines whether an item is annotated with an attribute.
2209 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2210 if cfg!(debug_assertions) && !did.is_local() && rustc_feature::is_builtin_only_local(attr) {
2211 bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr);
2213 self.get_attrs(did, attr).next().is_some()
2217 /// Returns `true` if this is an `auto trait`.
2218 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2219 self.trait_def(trait_def_id).has_auto_impl
2222 /// Returns layout of a generator. Layout might be unavailable if the
2223 /// generator is tainted by errors.
2224 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2225 self.optimized_mir(def_id).generator_layout()
2228 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2229 /// If it implements no trait, returns `None`.
2230 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2231 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2234 /// If the given `DefId` describes a method belonging to an impl, returns the
2235 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2236 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2237 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
2238 TraitContainer(_) => None,
2239 ImplContainer(def_id) => Some(def_id),
2243 /// If the given `DefId` belongs to a trait that was automatically derived, returns `true`.
2244 pub fn is_builtin_derive(self, def_id: DefId) -> bool {
2245 self.has_attr(def_id, sym::automatically_derived)
2248 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2249 /// with the name of the crate containing the impl.
2250 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2251 if let Some(impl_did) = impl_did.as_local() {
2252 Ok(self.def_span(impl_did))
2254 Err(self.crate_name(impl_did.krate))
2258 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2259 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2260 /// definition's parent/scope to perform comparison.
2261 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2262 // We could use `Ident::eq` here, but we deliberately don't. The name
2263 // comparison fails frequently, and we want to avoid the expensive
2264 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2265 use_name.name == def_name.name
2269 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2272 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2273 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2277 pub fn adjust_ident_and_get_scope(
2282 ) -> (Ident, DefId) {
2285 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2286 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2287 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2291 pub fn is_object_safe(self, key: DefId) -> bool {
2292 self.object_safety_violations(key).is_empty()
2296 pub fn is_const_fn_raw(self, def_id: DefId) -> bool {
2297 matches!(self.def_kind(def_id), DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..))
2298 && self.impl_constness(def_id) == hir::Constness::Const
2302 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
2303 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
2304 let def_id = def_id.as_local()?;
2305 if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) {
2306 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2307 return match opaque_ty.origin {
2308 hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
2311 hir::OpaqueTyOrigin::TyAlias => None,
2318 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2320 ast::IntTy::Isize => IntTy::Isize,
2321 ast::IntTy::I8 => IntTy::I8,
2322 ast::IntTy::I16 => IntTy::I16,
2323 ast::IntTy::I32 => IntTy::I32,
2324 ast::IntTy::I64 => IntTy::I64,
2325 ast::IntTy::I128 => IntTy::I128,
2329 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2331 ast::UintTy::Usize => UintTy::Usize,
2332 ast::UintTy::U8 => UintTy::U8,
2333 ast::UintTy::U16 => UintTy::U16,
2334 ast::UintTy::U32 => UintTy::U32,
2335 ast::UintTy::U64 => UintTy::U64,
2336 ast::UintTy::U128 => UintTy::U128,
2340 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2342 ast::FloatTy::F32 => FloatTy::F32,
2343 ast::FloatTy::F64 => FloatTy::F64,
2347 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2349 IntTy::Isize => ast::IntTy::Isize,
2350 IntTy::I8 => ast::IntTy::I8,
2351 IntTy::I16 => ast::IntTy::I16,
2352 IntTy::I32 => ast::IntTy::I32,
2353 IntTy::I64 => ast::IntTy::I64,
2354 IntTy::I128 => ast::IntTy::I128,
2358 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2360 UintTy::Usize => ast::UintTy::Usize,
2361 UintTy::U8 => ast::UintTy::U8,
2362 UintTy::U16 => ast::UintTy::U16,
2363 UintTy::U32 => ast::UintTy::U32,
2364 UintTy::U64 => ast::UintTy::U64,
2365 UintTy::U128 => ast::UintTy::U128,
2369 pub fn provide(providers: &mut ty::query::Providers) {
2370 closure::provide(providers);
2371 context::provide(providers);
2372 erase_regions::provide(providers);
2373 layout::provide(providers);
2374 util::provide(providers);
2375 print::provide(providers);
2376 super::util::bug::provide(providers);
2377 super::middle::provide(providers);
2378 *providers = ty::query::Providers {
2379 trait_impls_of: trait_def::trait_impls_of_provider,
2380 incoherent_impls: trait_def::incoherent_impls_provider,
2381 type_uninhabited_from: inhabitedness::type_uninhabited_from,
2382 const_param_default: consts::const_param_default,
2383 vtable_allocation: vtable::vtable_allocation_provider,
2388 /// A map for the local crate mapping each type to a vector of its
2389 /// inherent impls. This is not meant to be used outside of coherence;
2390 /// rather, you should request the vector for a specific type via
2391 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2392 /// (constructing this map requires touching the entire crate).
2393 #[derive(Clone, Debug, Default, HashStable)]
2394 pub struct CrateInherentImpls {
2395 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2396 pub incoherent_impls: FxHashMap<SimplifiedType, Vec<LocalDefId>>,
2399 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2400 pub struct SymbolName<'tcx> {
2401 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2402 pub name: &'tcx str,
2405 impl<'tcx> SymbolName<'tcx> {
2406 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2408 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2413 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2414 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2415 fmt::Display::fmt(&self.name, fmt)
2419 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2420 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2421 fmt::Display::fmt(&self.name, fmt)
2425 #[derive(Debug, Default, Copy, Clone)]
2426 pub struct FoundRelationships {
2427 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2428 /// obligation, where:
2430 /// * `Foo` is not `Sized`
2431 /// * `(): Foo` may be satisfied
2432 pub self_in_trait: bool,
2433 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2434 /// _>::AssocType = ?T`