1 //! Defines how the compiler represents types internally.
3 //! Two important entities in this module are:
5 //! - [`rustc_middle::ty::Ty`], used to represent the semantics of a type.
6 //! - [`rustc_middle::ty::TyCtxt`], the central data structure in the compiler.
8 //! For more information, see ["The `ty` module: representing types"] in the ructc-dev-guide.
10 //! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html
12 pub use self::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeVisitor};
13 pub use self::AssocItemContainer::*;
14 pub use self::BorrowKind::*;
15 pub use self::IntVarValue::*;
16 pub use self::Variance::*;
22 use crate::metadata::ModChild;
23 use crate::middle::privacy::AccessLevels;
24 use crate::mir::{Body, GeneratorLayout};
25 use crate::traits::{self, Reveal};
27 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
28 use crate::ty::util::Discr;
30 use rustc_attr as attr;
31 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
32 use rustc_data_structures::intern::Interned;
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, CRATE_DEF_INDEX};
39 use rustc_macros::HashStable;
40 use rustc_query_system::ich::StableHashingContext;
41 use rustc_session::cstore::CrateStoreDyn;
42 use rustc_span::symbol::{kw, Ident, Symbol};
43 use rustc_span::{sym, Span};
44 use rustc_target::abi::Align;
47 use std::ops::ControlFlow;
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, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath,
62 pub use self::consts::{
63 Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, Unevaluated, ValTree,
65 pub use self::context::{
66 tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
67 CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorInteriorTypeCause, GlobalCtxt,
68 Lift, OnDiskCache, TyCtxt, TypeckResults, UserType, UserTypeAnnotationIndex,
70 pub use self::instance::{Instance, InstanceDef};
71 pub use self::list::List;
72 pub use self::sty::BoundRegionKind::*;
73 pub use self::sty::RegionKind::*;
74 pub use self::sty::TyKind::*;
76 Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind,
77 CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBoundRegion,
78 ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig,
79 GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts, InlineConstSubstsParts, ParamConst,
80 ParamTy, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig,
81 PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut,
82 UpvarSubsts, VarianceDiagInfo,
84 pub use self::trait_def::TraitDef;
95 pub mod inhabitedness;
97 pub mod normalize_erasing_regions;
118 mod structural_impls;
123 pub type RegisteredTools = FxHashSet<Ident>;
126 pub struct ResolverOutputs {
127 pub definitions: rustc_hir::definitions::Definitions,
128 pub cstore: Box<CrateStoreDyn>,
129 pub visibilities: FxHashMap<LocalDefId, Visibility>,
130 pub access_levels: AccessLevels,
131 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
132 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
133 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
134 pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
135 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
136 /// Extern prelude entries. The value is `true` if the entry was introduced
137 /// via `extern crate` item and not `--extern` option or compiler built-in.
138 pub extern_prelude: FxHashMap<Symbol, bool>,
139 pub main_def: Option<MainDefinition>,
140 pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
141 /// A list of proc macro LocalDefIds, written out in the order in which
142 /// they are declared in the static array generated by proc_macro_harness.
143 pub proc_macros: Vec<LocalDefId>,
144 /// Mapping from ident span to path span for paths that don't exist as written, but that
145 /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
146 pub confused_type_with_std_module: FxHashMap<Span, Span>,
147 pub registered_tools: RegisteredTools,
150 #[derive(Clone, Copy, Debug)]
151 pub struct MainDefinition {
152 pub res: Res<ast::NodeId>,
157 impl MainDefinition {
158 pub fn opt_fn_def_id(self) -> Option<DefId> {
159 if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
163 /// The "header" of an impl is everything outside the body: a Self type, a trait
164 /// ref (in the case of a trait impl), and a set of predicates (from the
165 /// bounds / where-clauses).
166 #[derive(Clone, Debug, TypeFoldable)]
167 pub struct ImplHeader<'tcx> {
168 pub impl_def_id: DefId,
169 pub self_ty: Ty<'tcx>,
170 pub trait_ref: Option<TraitRef<'tcx>>,
171 pub predicates: Vec<Predicate<'tcx>>,
186 pub enum ImplPolarity {
187 /// `impl Trait for Type`
189 /// `impl !Trait for Type`
191 /// `#[rustc_reservation_impl] impl Trait for Type`
193 /// This is a "stability hack", not a real Rust feature.
194 /// See #64631 for details.
199 /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
200 pub fn flip(&self) -> Option<ImplPolarity> {
202 ImplPolarity::Positive => Some(ImplPolarity::Negative),
203 ImplPolarity::Negative => Some(ImplPolarity::Positive),
204 ImplPolarity::Reservation => None,
209 impl fmt::Display for ImplPolarity {
210 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
212 Self::Positive => f.write_str("positive"),
213 Self::Negative => f.write_str("negative"),
214 Self::Reservation => f.write_str("reservation"),
219 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
220 pub enum Visibility {
221 /// Visible everywhere (including in other crates).
223 /// Visible only in the given crate-local module.
225 /// Not visible anywhere in the local crate. This is the visibility of private external items.
229 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
230 pub enum BoundConstness {
233 /// `T: ~const Trait`
235 /// Requires resolving to const only when we are in a const context.
239 impl BoundConstness {
240 /// Reduce `self` and `constness` to two possible combined states instead of four.
241 pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
242 match (constness, self) {
243 (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
245 *this = BoundConstness::NotConst;
246 hir::Constness::NotConst
252 impl fmt::Display for BoundConstness {
253 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
255 Self::NotConst => f.write_str("normal"),
256 Self::ConstIfConst => f.write_str("`~const`"),
273 pub struct ClosureSizeProfileData<'tcx> {
274 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
275 pub before_feature_tys: Ty<'tcx>,
276 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
277 pub after_feature_tys: Ty<'tcx>,
280 pub trait DefIdTree: Copy {
281 fn parent(self, id: DefId) -> Option<DefId>;
283 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
284 if descendant.krate != ancestor.krate {
288 while descendant != ancestor {
289 match self.parent(descendant) {
290 Some(parent) => descendant = parent,
291 None => return false,
298 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
299 fn parent(self, id: DefId) -> Option<DefId> {
300 self.def_key(id).parent.map(|index| DefId { index, ..id })
305 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
306 match visibility.node {
307 hir::VisibilityKind::Public => Visibility::Public,
308 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
309 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
310 // If there is no resolution, `resolve` will have already reported an error, so
311 // assume that the visibility is public to avoid reporting more privacy errors.
312 Res::Err => Visibility::Public,
313 def => Visibility::Restricted(def.def_id()),
315 hir::VisibilityKind::Inherited => {
316 Visibility::Restricted(tcx.parent_module(id).to_def_id())
321 /// Returns `true` if an item with this visibility is accessible from the given block.
322 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
323 let restriction = match self {
324 // Public items are visible everywhere.
325 Visibility::Public => return true,
326 // Private items from other crates are visible nowhere.
327 Visibility::Invisible => return false,
328 // Restricted items are visible in an arbitrary local module.
329 Visibility::Restricted(other) if other.krate != module.krate => return false,
330 Visibility::Restricted(module) => module,
333 tree.is_descendant_of(module, restriction)
336 /// Returns `true` if this visibility is at least as accessible as the given visibility
337 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
338 let vis_restriction = match vis {
339 Visibility::Public => return self == Visibility::Public,
340 Visibility::Invisible => return true,
341 Visibility::Restricted(module) => module,
344 self.is_accessible_from(vis_restriction, tree)
347 // Returns `true` if this item is visible anywhere in the local crate.
348 pub fn is_visible_locally(self) -> bool {
350 Visibility::Public => true,
351 Visibility::Restricted(def_id) => def_id.is_local(),
352 Visibility::Invisible => false,
356 pub fn is_public(self) -> bool {
357 matches!(self, Visibility::Public)
361 /// The crate variances map is computed during typeck and contains the
362 /// variance of every item in the local crate. You should not use it
363 /// directly, because to do so will make your pass dependent on the
364 /// HIR of every item in the local crate. Instead, use
365 /// `tcx.variances_of()` to get the variance for a *particular*
367 #[derive(HashStable, Debug)]
368 pub struct CrateVariancesMap<'tcx> {
369 /// For each item with generics, maps to a vector of the variance
370 /// of its generics. If an item has no generics, it will have no
372 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
375 // Contains information needed to resolve types and (in the future) look up
376 // the types of AST nodes.
377 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
378 pub struct CReaderCacheKey {
379 pub cnum: Option<CrateNum>,
383 /// Represents a type.
386 /// - This is a very "dumb" struct (with no derives and no `impls`).
387 /// - Values of this type are always interned and thus unique, and are stored
388 /// as an `Interned<TyS>`.
389 /// - `Ty` (which contains a reference to a `Interned<TyS>`) or `Interned<TyS>`
390 /// should be used everywhere instead of `TyS`. In particular, `Ty` has most
391 /// of the relevant methods.
392 #[derive(PartialEq, Eq, PartialOrd, Ord)]
393 #[allow(rustc::usage_of_ty_tykind)]
394 crate struct TyS<'tcx> {
395 /// This field shouldn't be used directly and may be removed in the future.
396 /// Use `Ty::kind()` instead.
399 /// This field provides fast access to information that is also contained
402 /// This field shouldn't be used directly and may be removed in the future.
403 /// Use `Ty::flags()` instead.
406 /// This field provides fast access to information that is also contained
409 /// This is a kind of confusing thing: it stores the smallest
412 /// (a) the binder itself captures nothing but
413 /// (b) all the late-bound things within the type are captured
414 /// by some sub-binder.
416 /// So, for a type without any late-bound things, like `u32`, this
417 /// will be *innermost*, because that is the innermost binder that
418 /// captures nothing. But for a type `&'D u32`, where `'D` is a
419 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
420 /// -- the binder itself does not capture `D`, but `D` is captured
421 /// by an inner binder.
423 /// We call this concept an "exclusive" binder `D` because all
424 /// De Bruijn indices within the type are contained within `0..D`
426 outer_exclusive_binder: ty::DebruijnIndex,
429 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
430 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
431 static_assert_size!(TyS<'_>, 40);
433 /// Use this rather than `TyS`, whenever possible.
434 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
435 #[rustc_diagnostic_item = "Ty"]
436 #[cfg_attr(not(bootstrap), rustc_pass_by_value)]
437 pub struct Ty<'tcx>(Interned<'tcx, TyS<'tcx>>);
439 // Statics only used for internal testing.
440 pub static BOOL_TY: Ty<'static> = Ty(Interned::new_unchecked(&BOOL_TYS));
441 static BOOL_TYS: TyS<'static> = TyS {
443 flags: TypeFlags::empty(),
444 outer_exclusive_binder: DebruijnIndex::from_usize(0),
447 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Ty<'tcx> {
448 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
452 // The other fields just provide fast access to information that is
453 // also contained in `kind`, so no need to hash them.
456 outer_exclusive_binder: _,
459 kind.hash_stable(hcx, hasher);
463 impl ty::EarlyBoundRegion {
464 /// Does this early bound region have a name? Early bound regions normally
465 /// always have names except when using anonymous lifetimes (`'_`).
466 pub fn has_name(&self) -> bool {
467 self.name != kw::UnderscoreLifetime
471 /// Represents a predicate.
473 /// See comments on `TyS`, which apply here too (albeit for
474 /// `PredicateS`/`Predicate` rather than `TyS`/`Ty`).
476 crate struct PredicateS<'tcx> {
477 kind: Binder<'tcx, PredicateKind<'tcx>>,
479 /// See the comment for the corresponding field of [TyS].
480 outer_exclusive_binder: ty::DebruijnIndex,
483 // This type is used a lot. Make sure it doesn't unintentionally get bigger.
484 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
485 static_assert_size!(PredicateS<'_>, 56);
487 /// Use this rather than `PredicateS`, whenever possible.
488 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
489 #[cfg_attr(not(bootstrap), rustc_pass_by_value)]
490 pub struct Predicate<'tcx>(Interned<'tcx, PredicateS<'tcx>>);
492 impl<'tcx> Predicate<'tcx> {
493 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
495 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
500 pub fn flags(self) -> TypeFlags {
505 pub fn outer_exclusive_binder(self) -> DebruijnIndex {
506 self.0.outer_exclusive_binder
509 /// Flips the polarity of a Predicate.
511 /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
512 pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
515 .map_bound(|kind| match kind {
516 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
517 Some(PredicateKind::Trait(TraitPredicate {
520 polarity: polarity.flip()?,
528 Some(tcx.mk_predicate(kind))
532 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
533 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
537 // The other fields just provide fast access to information that is
538 // also contained in `kind`, so no need to hash them.
540 outer_exclusive_binder: _,
543 kind.hash_stable(hcx, hasher);
547 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
548 #[derive(HashStable, TypeFoldable)]
549 pub enum PredicateKind<'tcx> {
550 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
551 /// the `Self` type of the trait reference and `A`, `B`, and `C`
552 /// would be the type parameters.
553 Trait(TraitPredicate<'tcx>),
556 RegionOutlives(RegionOutlivesPredicate<'tcx>),
559 TypeOutlives(TypeOutlivesPredicate<'tcx>),
561 /// `where <T as TraitRef>::Name == X`, approximately.
562 /// See the `ProjectionPredicate` struct for details.
563 Projection(ProjectionPredicate<'tcx>),
565 /// No syntax: `T` well-formed.
566 WellFormed(GenericArg<'tcx>),
568 /// Trait must be object-safe.
571 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
572 /// for some substitutions `...` and `T` being a closure type.
573 /// Satisfied (or refuted) once we know the closure's kind.
574 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
578 /// This obligation is created most often when we have two
579 /// unresolved type variables and hence don't have enough
580 /// information to process the subtyping obligation yet.
581 Subtype(SubtypePredicate<'tcx>),
583 /// `T1` coerced to `T2`
585 /// Like a subtyping obligation, this is created most often
586 /// when we have two unresolved type variables and hence
587 /// don't have enough information to process the coercion
588 /// obligation yet. At the moment, we actually process coercions
589 /// very much like subtyping and don't handle the full coercion
591 Coerce(CoercePredicate<'tcx>),
593 /// Constant initializer must evaluate successfully.
594 ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
596 /// Constants must be equal. The first component is the const that is expected.
597 ConstEquate(Const<'tcx>, Const<'tcx>),
599 /// Represents a type found in the environment that we can use for implied bounds.
601 /// Only used for Chalk.
602 TypeWellFormedFromEnv(Ty<'tcx>),
605 /// The crate outlives map is computed during typeck and contains the
606 /// outlives of every item in the local crate. You should not use it
607 /// directly, because to do so will make your pass dependent on the
608 /// HIR of every item in the local crate. Instead, use
609 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
611 #[derive(HashStable, Debug)]
612 pub struct CratePredicatesMap<'tcx> {
613 /// For each struct with outlive bounds, maps to a vector of the
614 /// predicate of its outlive bounds. If an item has no outlives
615 /// bounds, it will have no entry.
616 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
619 impl<'tcx> Predicate<'tcx> {
620 /// Performs a substitution suitable for going from a
621 /// poly-trait-ref to supertraits that must hold if that
622 /// poly-trait-ref holds. This is slightly different from a normal
623 /// substitution in terms of what happens with bound regions. See
624 /// lengthy comment below for details.
625 pub fn subst_supertrait(
628 trait_ref: &ty::PolyTraitRef<'tcx>,
629 ) -> Predicate<'tcx> {
630 // The interaction between HRTB and supertraits is not entirely
631 // obvious. Let me walk you (and myself) through an example.
633 // Let's start with an easy case. Consider two traits:
635 // trait Foo<'a>: Bar<'a,'a> { }
636 // trait Bar<'b,'c> { }
638 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
639 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
640 // knew that `Foo<'x>` (for any 'x) then we also know that
641 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
642 // normal substitution.
644 // In terms of why this is sound, the idea is that whenever there
645 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
646 // holds. So if there is an impl of `T:Foo<'a>` that applies to
647 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
650 // Another example to be careful of is this:
652 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
653 // trait Bar1<'b,'c> { }
655 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
656 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
657 // reason is similar to the previous example: any impl of
658 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
659 // basically we would want to collapse the bound lifetimes from
660 // the input (`trait_ref`) and the supertraits.
662 // To achieve this in practice is fairly straightforward. Let's
663 // consider the more complicated scenario:
665 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
666 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
667 // where both `'x` and `'b` would have a DB index of 1.
668 // The substitution from the input trait-ref is therefore going to be
669 // `'a => 'x` (where `'x` has a DB index of 1).
670 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
671 // early-bound parameter and `'b' is a late-bound parameter with a
673 // - If we replace `'a` with `'x` from the input, it too will have
674 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
675 // just as we wanted.
677 // There is only one catch. If we just apply the substitution `'a
678 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
679 // adjust the DB index because we substituting into a binder (it
680 // tries to be so smart...) resulting in `for<'x> for<'b>
681 // Bar1<'x,'b>` (we have no syntax for this, so use your
682 // imagination). Basically the 'x will have DB index of 2 and 'b
683 // will have DB index of 1. Not quite what we want. So we apply
684 // the substitution to the *contents* of the trait reference,
685 // rather than the trait reference itself (put another way, the
686 // substitution code expects equal binding levels in the values
687 // from the substitution and the value being substituted into, and
688 // this trick achieves that).
690 // Working through the second example:
691 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
692 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
693 // We want to end up with:
694 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
696 // 1) We must shift all bound vars in predicate by the length
697 // of trait ref's bound vars. So, we would end up with predicate like
698 // Self: Bar1<'a, '^0.1>
699 // 2) We can then apply the trait substs to this, ending up with
700 // T: Bar1<'^0.0, '^0.1>
701 // 3) Finally, to create the final bound vars, we concatenate the bound
702 // vars of the trait ref with those of the predicate:
704 let bound_pred = self.kind();
705 let pred_bound_vars = bound_pred.bound_vars();
706 let trait_bound_vars = trait_ref.bound_vars();
707 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
709 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
710 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
711 let new = shifted_pred.subst(tcx, trait_ref.skip_binder().substs);
712 // 3) ['x] + ['b] -> ['x, 'b]
714 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
715 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
719 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
720 #[derive(HashStable, TypeFoldable)]
721 pub struct TraitPredicate<'tcx> {
722 pub trait_ref: TraitRef<'tcx>,
724 pub constness: BoundConstness,
726 pub polarity: ImplPolarity,
729 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
731 impl<'tcx> TraitPredicate<'tcx> {
732 pub fn remap_constness(&mut self, tcx: TyCtxt<'tcx>, param_env: &mut ParamEnv<'tcx>) {
733 if unlikely!(Some(self.trait_ref.def_id) == tcx.lang_items().drop_trait()) {
734 // remap without changing constness of this predicate.
735 // this is because `T: ~const Drop` has a different meaning to `T: Drop`
736 param_env.remap_constness_with(self.constness)
738 *param_env = param_env.with_constness(self.constness.and(param_env.constness()))
742 /// Remap the constness of this predicate before emitting it for diagnostics.
743 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
744 // this is different to `remap_constness` that callees want to print this predicate
745 // in case of selection errors. `T: ~const Drop` bounds cannot end up here when the
746 // param_env is not const because we it is always satisfied in non-const contexts.
747 if let hir::Constness::NotConst = param_env.constness() {
748 self.constness = ty::BoundConstness::NotConst;
752 pub fn def_id(self) -> DefId {
753 self.trait_ref.def_id
756 pub fn self_ty(self) -> Ty<'tcx> {
757 self.trait_ref.self_ty()
761 pub fn is_const_if_const(self) -> bool {
762 self.constness == BoundConstness::ConstIfConst
766 impl<'tcx> PolyTraitPredicate<'tcx> {
767 pub fn def_id(self) -> DefId {
768 // Ok to skip binder since trait `DefId` does not care about regions.
769 self.skip_binder().def_id()
772 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
773 self.map_bound(|trait_ref| trait_ref.self_ty())
776 /// Remap the constness of this predicate before emitting it for diagnostics.
777 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
778 *self = self.map_bound(|mut p| {
779 p.remap_constness_diag(param_env);
785 pub fn is_const_if_const(self) -> bool {
786 self.skip_binder().is_const_if_const()
790 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
791 #[derive(HashStable, TypeFoldable)]
792 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
793 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
794 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
795 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
796 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
798 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
799 /// whether the `a` type is the type that we should label as "expected" when
800 /// presenting user diagnostics.
801 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
802 #[derive(HashStable, TypeFoldable)]
803 pub struct SubtypePredicate<'tcx> {
804 pub a_is_expected: bool,
808 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
810 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
811 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
812 #[derive(HashStable, TypeFoldable)]
813 pub struct CoercePredicate<'tcx> {
817 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
819 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)]
820 #[derive(HashStable, TypeFoldable)]
821 pub enum Term<'tcx> {
826 impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
827 fn from(ty: Ty<'tcx>) -> Self {
832 impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
833 fn from(c: Const<'tcx>) -> Self {
838 impl<'tcx> Term<'tcx> {
839 pub fn ty(&self) -> Option<Ty<'tcx>> {
840 if let Term::Ty(ty) = self { Some(*ty) } else { None }
842 pub fn ct(&self) -> Option<Const<'tcx>> {
843 if let Term::Const(c) = self { Some(*c) } else { None }
847 /// This kind of predicate has no *direct* correspondent in the
848 /// syntax, but it roughly corresponds to the syntactic forms:
850 /// 1. `T: TraitRef<..., Item = Type>`
851 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
853 /// In particular, form #1 is "desugared" to the combination of a
854 /// normal trait predicate (`T: TraitRef<...>`) and one of these
855 /// predicates. Form #2 is a broader form in that it also permits
856 /// equality between arbitrary types. Processing an instance of
857 /// Form #2 eventually yields one of these `ProjectionPredicate`
858 /// instances to normalize the LHS.
859 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
860 #[derive(HashStable, TypeFoldable)]
861 pub struct ProjectionPredicate<'tcx> {
862 pub projection_ty: ProjectionTy<'tcx>,
863 pub term: Term<'tcx>,
866 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
868 impl<'tcx> PolyProjectionPredicate<'tcx> {
869 /// Returns the `DefId` of the trait of the associated item being projected.
871 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
872 self.skip_binder().projection_ty.trait_def_id(tcx)
875 /// Get the [PolyTraitRef] required for this projection to be well formed.
876 /// Note that for generic associated types the predicates of the associated
877 /// type also need to be checked.
879 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
880 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
881 // `self.0.trait_ref` is permitted to have escaping regions.
882 // This is because here `self` has a `Binder` and so does our
883 // return value, so we are preserving the number of binding
885 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
888 pub fn term(&self) -> Binder<'tcx, Term<'tcx>> {
889 self.map_bound(|predicate| predicate.term)
892 /// The `DefId` of the `TraitItem` for the associated type.
894 /// Note that this is not the `DefId` of the `TraitRef` containing this
895 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
896 pub fn projection_def_id(&self) -> DefId {
897 // Ok to skip binder since trait `DefId` does not care about regions.
898 self.skip_binder().projection_ty.item_def_id
902 pub trait ToPolyTraitRef<'tcx> {
903 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
906 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
907 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
908 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
912 pub trait ToPredicate<'tcx> {
913 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
916 impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
918 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
919 tcx.mk_predicate(self)
923 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
924 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
925 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
929 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
930 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
931 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
935 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
936 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
937 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
941 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
942 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
943 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
947 impl<'tcx> Predicate<'tcx> {
948 pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
949 let predicate = self.kind();
950 match predicate.skip_binder() {
951 PredicateKind::Trait(t) => Some(predicate.rebind(t)),
952 PredicateKind::Projection(..)
953 | PredicateKind::Subtype(..)
954 | PredicateKind::Coerce(..)
955 | PredicateKind::RegionOutlives(..)
956 | PredicateKind::WellFormed(..)
957 | PredicateKind::ObjectSafe(..)
958 | PredicateKind::ClosureKind(..)
959 | PredicateKind::TypeOutlives(..)
960 | PredicateKind::ConstEvaluatable(..)
961 | PredicateKind::ConstEquate(..)
962 | PredicateKind::TypeWellFormedFromEnv(..) => None,
966 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
967 let predicate = self.kind();
968 match predicate.skip_binder() {
969 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
970 PredicateKind::Trait(..)
971 | PredicateKind::Projection(..)
972 | PredicateKind::Subtype(..)
973 | PredicateKind::Coerce(..)
974 | PredicateKind::RegionOutlives(..)
975 | PredicateKind::WellFormed(..)
976 | PredicateKind::ObjectSafe(..)
977 | PredicateKind::ClosureKind(..)
978 | PredicateKind::ConstEvaluatable(..)
979 | PredicateKind::ConstEquate(..)
980 | PredicateKind::TypeWellFormedFromEnv(..) => None,
985 /// Represents the bounds declared on a particular set of type
986 /// parameters. Should eventually be generalized into a flag list of
987 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
988 /// `GenericPredicates` by using the `instantiate` method. Note that this method
989 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
990 /// the `GenericPredicates` are expressed in terms of the bound type
991 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
992 /// represented a set of bounds for some particular instantiation,
993 /// meaning that the generic parameters have been substituted with
998 /// struct Foo<T, U: Bar<T>> { ... }
1000 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1001 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1002 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1003 /// [usize:Bar<isize>]]`.
1004 #[derive(Clone, Debug, TypeFoldable)]
1005 pub struct InstantiatedPredicates<'tcx> {
1006 pub predicates: Vec<Predicate<'tcx>>,
1007 pub spans: Vec<Span>,
1010 impl<'tcx> InstantiatedPredicates<'tcx> {
1011 pub fn empty() -> InstantiatedPredicates<'tcx> {
1012 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1015 pub fn is_empty(&self) -> bool {
1016 self.predicates.is_empty()
1020 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable, TypeFoldable)]
1021 pub struct OpaqueTypeKey<'tcx> {
1023 pub substs: SubstsRef<'tcx>,
1026 rustc_index::newtype_index! {
1027 /// "Universes" are used during type- and trait-checking in the
1028 /// presence of `for<..>` binders to control what sets of names are
1029 /// visible. Universes are arranged into a tree: the root universe
1030 /// contains names that are always visible. Each child then adds a new
1031 /// set of names that are visible, in addition to those of its parent.
1032 /// We say that the child universe "extends" the parent universe with
1035 /// To make this more concrete, consider this program:
1039 /// fn bar<T>(x: T) {
1040 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1044 /// The struct name `Foo` is in the root universe U0. But the type
1045 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1046 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1047 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1048 /// region `'a` is in a universe U2 that extends U1, because we can
1049 /// name it inside the fn type but not outside.
1051 /// Universes are used to do type- and trait-checking around these
1052 /// "forall" binders (also called **universal quantification**). The
1053 /// idea is that when, in the body of `bar`, we refer to `T` as a
1054 /// type, we aren't referring to any type in particular, but rather a
1055 /// kind of "fresh" type that is distinct from all other types we have
1056 /// actually declared. This is called a **placeholder** type, and we
1057 /// use universes to talk about this. In other words, a type name in
1058 /// universe 0 always corresponds to some "ground" type that the user
1059 /// declared, but a type name in a non-zero universe is a placeholder
1060 /// type -- an idealized representative of "types in general" that we
1061 /// use for checking generic functions.
1062 pub struct UniverseIndex {
1064 DEBUG_FORMAT = "U{}",
1068 impl UniverseIndex {
1069 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1071 /// Returns the "next" universe index in order -- this new index
1072 /// is considered to extend all previous universes. This
1073 /// corresponds to entering a `forall` quantifier. So, for
1074 /// example, suppose we have this type in universe `U`:
1077 /// for<'a> fn(&'a u32)
1080 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1081 /// new universe that extends `U` -- in this new universe, we can
1082 /// name the region `'a`, but that region was not nameable from
1083 /// `U` because it was not in scope there.
1084 pub fn next_universe(self) -> UniverseIndex {
1085 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1088 /// Returns `true` if `self` can name a name from `other` -- in other words,
1089 /// if the set of names in `self` is a superset of those in
1090 /// `other` (`self >= other`).
1091 pub fn can_name(self, other: UniverseIndex) -> bool {
1092 self.private >= other.private
1095 /// Returns `true` if `self` cannot name some names from `other` -- in other
1096 /// words, if the set of names in `self` is a strict subset of
1097 /// those in `other` (`self < other`).
1098 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1099 self.private < other.private
1103 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1104 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1105 /// regions/types/consts within the same universe simply have an unknown relationship to one
1107 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1108 pub struct Placeholder<T> {
1109 pub universe: UniverseIndex,
1113 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1115 T: HashStable<StableHashingContext<'a>>,
1117 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1118 self.universe.hash_stable(hcx, hasher);
1119 self.name.hash_stable(hcx, hasher);
1123 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1125 pub type PlaceholderType = Placeholder<BoundVar>;
1127 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1128 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1129 pub struct BoundConst<'tcx> {
1134 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1136 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1137 /// the `DefId` of the generic parameter it instantiates.
1139 /// This is used to avoid calls to `type_of` for const arguments during typeck
1140 /// which cause cycle errors.
1145 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1146 /// // ^ const parameter
1150 /// fn foo<const M: u8>(&self) -> usize { 42 }
1151 /// // ^ const parameter
1156 /// let _b = a.foo::<{ 3 + 7 }>();
1157 /// // ^^^^^^^^^ const argument
1161 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1162 /// which `foo` is used until we know the type of `a`.
1164 /// We only know the type of `a` once we are inside of `typeck(main)`.
1165 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1166 /// requires us to evaluate the const argument.
1168 /// To evaluate that const argument we need to know its type,
1169 /// which we would get using `type_of(const_arg)`. This requires us to
1170 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1171 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1172 /// which results in a cycle.
1174 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1176 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1177 /// already resolved `foo` so we know which const parameter this argument instantiates.
1178 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1179 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1180 /// trivial to compute.
1182 /// If we now want to use that constant in a place which potentionally needs its type
1183 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1184 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1185 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1186 /// to get the type of `did`.
1187 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1188 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1189 #[derive(Hash, HashStable)]
1190 pub struct WithOptConstParam<T> {
1192 /// The `DefId` of the corresponding generic parameter in case `did` is
1193 /// a const argument.
1195 /// Note that even if `did` is a const argument, this may still be `None`.
1196 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1197 /// to potentially update `param_did` in the case it is `None`.
1198 pub const_param_did: Option<DefId>,
1201 impl<T> WithOptConstParam<T> {
1202 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1204 pub fn unknown(did: T) -> WithOptConstParam<T> {
1205 WithOptConstParam { did, const_param_did: None }
1209 impl WithOptConstParam<LocalDefId> {
1210 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1211 /// `None` otherwise.
1213 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1214 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1217 /// In case `self` is unknown but `self.did` is a const argument, this returns
1218 /// a `WithOptConstParam` with the correct `const_param_did`.
1220 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1221 if self.const_param_did.is_none() {
1222 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1223 return Some(WithOptConstParam { did: self.did, const_param_did });
1230 pub fn to_global(self) -> WithOptConstParam<DefId> {
1231 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1234 pub fn def_id_for_type_of(self) -> DefId {
1235 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1239 impl WithOptConstParam<DefId> {
1240 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1243 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1246 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1247 if let Some(param_did) = self.const_param_did {
1248 if let Some(did) = self.did.as_local() {
1249 return Some((did, param_did));
1256 pub fn is_local(self) -> bool {
1260 pub fn def_id_for_type_of(self) -> DefId {
1261 self.const_param_did.unwrap_or(self.did)
1265 /// When type checking, we use the `ParamEnv` to track
1266 /// details about the set of where-clauses that are in scope at this
1267 /// particular point.
1268 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1269 pub struct ParamEnv<'tcx> {
1270 /// This packs both caller bounds and the reveal enum into one pointer.
1272 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1273 /// basically the set of bounds on the in-scope type parameters, translated
1274 /// into `Obligation`s, and elaborated and normalized.
1276 /// Use the `caller_bounds()` method to access.
1278 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1279 /// want `Reveal::All`.
1281 /// Note: This is packed, use the reveal() method to access it.
1282 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
1285 #[derive(Copy, Clone)]
1287 reveal: traits::Reveal,
1288 constness: hir::Constness,
1291 unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
1292 const BITS: usize = 2;
1294 fn into_usize(self) -> usize {
1296 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
1297 Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
1298 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
1299 Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
1303 unsafe fn from_usize(ptr: usize) -> Self {
1305 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1306 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
1307 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
1308 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
1309 _ => std::hint::unreachable_unchecked(),
1314 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1315 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1316 f.debug_struct("ParamEnv")
1317 .field("caller_bounds", &self.caller_bounds())
1318 .field("reveal", &self.reveal())
1319 .field("constness", &self.constness())
1324 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1325 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1326 self.caller_bounds().hash_stable(hcx, hasher);
1327 self.reveal().hash_stable(hcx, hasher);
1328 self.constness().hash_stable(hcx, hasher);
1332 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1333 fn try_super_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
1336 ) -> Result<Self, F::Error> {
1338 self.caller_bounds().try_fold_with(folder)?,
1339 self.reveal().try_fold_with(folder)?,
1340 self.constness().try_fold_with(folder)?,
1344 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1345 self.caller_bounds().visit_with(visitor)?;
1346 self.reveal().visit_with(visitor)?;
1347 self.constness().visit_with(visitor)
1351 impl<'tcx> ParamEnv<'tcx> {
1352 /// Construct a trait environment suitable for contexts where
1353 /// there are no where-clauses in scope. Hidden types (like `impl
1354 /// Trait`) are left hidden, so this is suitable for ordinary
1357 pub fn empty() -> Self {
1358 Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
1362 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1363 self.packed.pointer()
1367 pub fn reveal(self) -> traits::Reveal {
1368 self.packed.tag().reveal
1372 pub fn constness(self) -> hir::Constness {
1373 self.packed.tag().constness
1377 pub fn is_const(self) -> bool {
1378 self.packed.tag().constness == hir::Constness::Const
1381 /// Construct a trait environment with no where-clauses in scope
1382 /// where the values of all `impl Trait` and other hidden types
1383 /// are revealed. This is suitable for monomorphized, post-typeck
1384 /// environments like codegen or doing optimizations.
1386 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1387 /// or invoke `param_env.with_reveal_all()`.
1389 pub fn reveal_all() -> Self {
1390 Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
1393 /// Construct a trait environment with the given set of predicates.
1396 caller_bounds: &'tcx List<Predicate<'tcx>>,
1398 constness: hir::Constness,
1400 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
1403 pub fn with_user_facing(mut self) -> Self {
1404 self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
1409 pub fn with_constness(mut self, constness: hir::Constness) -> Self {
1410 self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
1415 pub fn with_const(mut self) -> Self {
1416 self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
1421 pub fn without_const(mut self) -> Self {
1422 self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
1427 pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
1428 *self = self.with_constness(constness.and(self.constness()))
1431 /// Returns a new parameter environment with the same clauses, but
1432 /// which "reveals" the true results of projections in all cases
1433 /// (even for associated types that are specializable). This is
1434 /// the desired behavior during codegen and certain other special
1435 /// contexts; normally though we want to use `Reveal::UserFacing`,
1436 /// which is the default.
1437 /// All opaque types in the caller_bounds of the `ParamEnv`
1438 /// will be normalized to their underlying types.
1439 /// See PR #65989 and issue #65918 for more details
1440 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1441 if self.packed.tag().reveal == traits::Reveal::All {
1446 tcx.normalize_opaque_types(self.caller_bounds()),
1452 /// Returns this same environment but with no caller bounds.
1454 pub fn without_caller_bounds(self) -> Self {
1455 Self::new(List::empty(), self.reveal(), self.constness())
1458 /// Creates a suitable environment in which to perform trait
1459 /// queries on the given value. When type-checking, this is simply
1460 /// the pair of the environment plus value. But when reveal is set to
1461 /// All, then if `value` does not reference any type parameters, we will
1462 /// pair it with the empty environment. This improves caching and is generally
1465 /// N.B., we preserve the environment when type-checking because it
1466 /// is possible for the user to have wacky where-clauses like
1467 /// `where Box<u32>: Copy`, which are clearly never
1468 /// satisfiable. We generally want to behave as if they were true,
1469 /// although the surrounding function is never reachable.
1470 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1471 match self.reveal() {
1472 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1475 if value.is_global() {
1476 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1478 ParamEnvAnd { param_env: self, value }
1485 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1486 // the constness of trait bounds is being propagated correctly.
1487 impl<'tcx> PolyTraitRef<'tcx> {
1489 pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
1490 self.map_bound(|trait_ref| ty::TraitPredicate {
1493 polarity: ty::ImplPolarity::Positive,
1498 pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
1499 self.with_constness(BoundConstness::NotConst)
1503 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1504 pub struct ParamEnvAnd<'tcx, T> {
1505 pub param_env: ParamEnv<'tcx>,
1509 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1510 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1511 (self.param_env, self.value)
1515 pub fn without_const(mut self) -> Self {
1516 self.param_env = self.param_env.without_const();
1521 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1523 T: HashStable<StableHashingContext<'a>>,
1525 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1526 let ParamEnvAnd { ref param_env, ref value } = *self;
1528 param_env.hash_stable(hcx, hasher);
1529 value.hash_stable(hcx, hasher);
1533 #[derive(Copy, Clone, Debug, HashStable)]
1534 pub struct Destructor {
1535 /// The `DefId` of the destructor method
1537 /// The constness of the destructor method
1538 pub constness: hir::Constness,
1542 #[derive(HashStable, TyEncodable, TyDecodable)]
1543 pub struct VariantFlags: u32 {
1544 const NO_VARIANT_FLAGS = 0;
1545 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1546 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1547 /// Indicates whether this variant was obtained as part of recovering from
1548 /// a syntactic error. May be incomplete or bogus.
1549 const IS_RECOVERED = 1 << 1;
1553 /// Definition of a variant -- a struct's fields or an enum variant.
1554 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1555 pub struct VariantDef {
1556 /// `DefId` that identifies the variant itself.
1557 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1559 /// `DefId` that identifies the variant's constructor.
1560 /// If this variant is a struct variant, then this is `None`.
1561 pub ctor_def_id: Option<DefId>,
1562 /// Variant or struct name.
1564 /// Discriminant of this variant.
1565 pub discr: VariantDiscr,
1566 /// Fields of this variant.
1567 pub fields: Vec<FieldDef>,
1568 /// Type of constructor of variant.
1569 pub ctor_kind: CtorKind,
1570 /// Flags of the variant (e.g. is field list non-exhaustive)?
1571 flags: VariantFlags,
1575 /// Creates a new `VariantDef`.
1577 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1578 /// represents an enum variant).
1580 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1581 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1583 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1584 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1585 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1586 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1587 /// built-in trait), and we do not want to load attributes twice.
1589 /// If someone speeds up attribute loading to not be a performance concern, they can
1590 /// remove this hack and use the constructor `DefId` everywhere.
1593 variant_did: Option<DefId>,
1594 ctor_def_id: Option<DefId>,
1595 discr: VariantDiscr,
1596 fields: Vec<FieldDef>,
1597 ctor_kind: CtorKind,
1601 is_field_list_non_exhaustive: bool,
1604 "VariantDef::new(name = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1605 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1606 name, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1609 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1610 if is_field_list_non_exhaustive {
1611 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1615 flags |= VariantFlags::IS_RECOVERED;
1619 def_id: variant_did.unwrap_or(parent_did),
1629 /// Is this field list non-exhaustive?
1631 pub fn is_field_list_non_exhaustive(&self) -> bool {
1632 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1635 /// Was this variant obtained as part of recovering from a syntactic error?
1637 pub fn is_recovered(&self) -> bool {
1638 self.flags.intersects(VariantFlags::IS_RECOVERED)
1641 /// Computes the `Ident` of this variant by looking up the `Span`
1642 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1643 Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1647 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1648 pub enum VariantDiscr {
1649 /// Explicit value for this variant, i.e., `X = 123`.
1650 /// The `DefId` corresponds to the embedded constant.
1653 /// The previous variant's discriminant plus one.
1654 /// For efficiency reasons, the distance from the
1655 /// last `Explicit` discriminant is being stored,
1656 /// or `0` for the first variant, if it has none.
1660 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1661 pub struct FieldDef {
1664 pub vis: Visibility,
1668 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1669 pub struct ReprFlags: u8 {
1670 const IS_C = 1 << 0;
1671 const IS_SIMD = 1 << 1;
1672 const IS_TRANSPARENT = 1 << 2;
1673 // Internal only for now. If true, don't reorder fields.
1674 const IS_LINEAR = 1 << 3;
1675 // If true, don't expose any niche to type's context.
1676 const HIDE_NICHE = 1 << 4;
1677 // If true, the type's layout can be randomized using
1678 // the seed stored in `ReprOptions.layout_seed`
1679 const RANDOMIZE_LAYOUT = 1 << 5;
1680 // Any of these flags being set prevent field reordering optimisation.
1681 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
1682 | ReprFlags::IS_SIMD.bits
1683 | ReprFlags::IS_LINEAR.bits;
1687 /// Represents the repr options provided by the user,
1688 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
1689 pub struct ReprOptions {
1690 pub int: Option<attr::IntType>,
1691 pub align: Option<Align>,
1692 pub pack: Option<Align>,
1693 pub flags: ReprFlags,
1694 /// The seed to be used for randomizing a type's layout
1696 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
1697 /// be the "most accurate" hash as it'd encompass the item and crate
1698 /// hash without loss, but it does pay the price of being larger.
1699 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
1700 /// purposes (primarily `-Z randomize-layout`)
1701 pub field_shuffle_seed: u64,
1705 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1706 let mut flags = ReprFlags::empty();
1707 let mut size = None;
1708 let mut max_align: Option<Align> = None;
1709 let mut min_pack: Option<Align> = None;
1711 // Generate a deterministically-derived seed from the item's path hash
1712 // to allow for cross-crate compilation to actually work
1713 let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
1715 // If the user defined a custom seed for layout randomization, xor the item's
1716 // path hash with the user defined seed, this will allowing determinism while
1717 // still allowing users to further randomize layout generation for e.g. fuzzing
1718 if let Some(user_seed) = tcx.sess.opts.debugging_opts.layout_seed {
1719 field_shuffle_seed ^= user_seed;
1722 for attr in tcx.get_attrs(did).iter() {
1723 for r in attr::find_repr_attrs(&tcx.sess, attr) {
1724 flags.insert(match r {
1725 attr::ReprC => ReprFlags::IS_C,
1726 attr::ReprPacked(pack) => {
1727 let pack = Align::from_bytes(pack as u64).unwrap();
1728 min_pack = Some(if let Some(min_pack) = min_pack {
1735 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1736 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
1737 attr::ReprSimd => ReprFlags::IS_SIMD,
1738 attr::ReprInt(i) => {
1742 attr::ReprAlign(align) => {
1743 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
1750 // If `-Z randomize-layout` was enabled for the type definition then we can
1751 // consider performing layout randomization
1752 if tcx.sess.opts.debugging_opts.randomize_layout {
1753 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1756 // This is here instead of layout because the choice must make it into metadata.
1757 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
1758 flags.insert(ReprFlags::IS_LINEAR);
1761 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1765 pub fn simd(&self) -> bool {
1766 self.flags.contains(ReprFlags::IS_SIMD)
1770 pub fn c(&self) -> bool {
1771 self.flags.contains(ReprFlags::IS_C)
1775 pub fn packed(&self) -> bool {
1780 pub fn transparent(&self) -> bool {
1781 self.flags.contains(ReprFlags::IS_TRANSPARENT)
1785 pub fn linear(&self) -> bool {
1786 self.flags.contains(ReprFlags::IS_LINEAR)
1790 pub fn hide_niche(&self) -> bool {
1791 self.flags.contains(ReprFlags::HIDE_NICHE)
1794 /// Returns the discriminant type, given these `repr` options.
1795 /// This must only be called on enums!
1796 pub fn discr_type(&self) -> attr::IntType {
1797 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1800 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
1801 /// layout" optimizations, such as representing `Foo<&T>` as a
1803 pub fn inhibit_enum_layout_opt(&self) -> bool {
1804 self.c() || self.int.is_some()
1807 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
1808 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
1809 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
1810 if let Some(pack) = self.pack {
1811 if pack.bytes() == 1 {
1816 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
1819 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
1820 /// was enabled for its declaration crate
1821 pub fn can_randomize_type_layout(&self) -> bool {
1822 !self.inhibit_struct_field_reordering_opt()
1823 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
1826 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
1827 pub fn inhibit_union_abi_opt(&self) -> bool {
1832 impl<'tcx> FieldDef {
1833 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
1834 /// typically obtained via the second field of [`TyKind::Adt`].
1835 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
1836 tcx.type_of(self.did).subst(tcx, subst)
1839 /// Computes the `Ident` of this variant by looking up the `Span`
1840 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1841 Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
1845 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
1847 #[derive(Debug, PartialEq, Eq)]
1848 pub enum ImplOverlapKind {
1849 /// These impls are always allowed to overlap.
1851 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1854 /// These impls are allowed to overlap, but that raises
1855 /// an issue #33140 future-compatibility warning.
1857 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
1858 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
1860 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
1861 /// that difference, making what reduces to the following set of impls:
1865 /// impl Trait for dyn Send + Sync {}
1866 /// impl Trait for dyn Sync + Send {}
1869 /// Obviously, once we made these types be identical, that code causes a coherence
1870 /// error and a fairly big headache for us. However, luckily for us, the trait
1871 /// `Trait` used in this case is basically a marker trait, and therefore having
1872 /// overlapping impls for it is sound.
1874 /// To handle this, we basically regard the trait as a marker trait, with an additional
1875 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
1876 /// it has the following restrictions:
1878 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
1880 /// 2. The trait-ref of both impls must be equal.
1881 /// 3. The trait-ref of both impls must be a trait object type consisting only of
1883 /// 4. Neither of the impls can have any where-clauses.
1885 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
1889 impl<'tcx> TyCtxt<'tcx> {
1890 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1891 self.typeck(self.hir().body_owner_def_id(body))
1894 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1895 self.associated_items(id)
1896 .in_definition_order()
1897 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
1900 fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
1901 self.hir().get_if_local(def_id).and_then(|node| node.ident())
1904 fn item_name_from_def_id(self, def_id: DefId) -> Option<Symbol> {
1905 if def_id.index == CRATE_DEF_INDEX {
1906 Some(self.crate_name(def_id.krate))
1908 let def_key = self.def_key(def_id);
1909 match def_key.disambiguated_data.data {
1910 // The name of a constructor is that of its parent.
1911 rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId {
1912 krate: def_id.krate,
1913 index: def_key.parent.unwrap(),
1915 _ => def_key.disambiguated_data.data.get_opt_name(),
1920 /// Look up the name of an item across crates. This does not look at HIR.
1922 /// When possible, this function should be used for cross-crate lookups over
1923 /// [`opt_item_name`] to avoid invalidating the incremental cache. If you
1924 /// need to handle items without a name, or HIR items that will not be
1925 /// serialized cross-crate, or if you need the span of the item, use
1926 /// [`opt_item_name`] instead.
1928 /// [`opt_item_name`]: Self::opt_item_name
1929 pub fn item_name(self, id: DefId) -> Symbol {
1930 // Look at cross-crate items first to avoid invalidating the incremental cache
1931 // unless we have to.
1932 self.item_name_from_def_id(id).unwrap_or_else(|| {
1933 bug!("item_name: no name for {:?}", self.def_path(id));
1937 /// Look up the name and span of an item or [`Node`].
1939 /// See [`item_name`][Self::item_name] for more information.
1940 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
1941 // Look at the HIR first so the span will be correct if this is a local item.
1942 self.item_name_from_hir(def_id)
1943 .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span))
1946 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
1947 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
1948 Some(self.associated_item(def_id))
1954 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
1955 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
1958 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
1962 .position(|field| self.hygienic_eq(ident, field.ident(self), variant.def_id))
1965 /// Returns `true` if the impls are the same polarity and the trait either
1966 /// has no items or is annotated `#[marker]` and prevents item overrides.
1967 pub fn impls_are_allowed_to_overlap(
1971 ) -> Option<ImplOverlapKind> {
1972 // If either trait impl references an error, they're allowed to overlap,
1973 // as one of them essentially doesn't exist.
1974 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
1975 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
1977 return Some(ImplOverlapKind::Permitted { marker: false });
1980 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
1981 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
1982 // `#[rustc_reservation_impl]` impls don't overlap with anything
1984 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
1987 return Some(ImplOverlapKind::Permitted { marker: false });
1989 (ImplPolarity::Positive, ImplPolarity::Negative)
1990 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
1991 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
1993 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
1998 (ImplPolarity::Positive, ImplPolarity::Positive)
1999 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2002 let is_marker_overlap = {
2003 let is_marker_impl = |def_id: DefId| -> bool {
2004 let trait_ref = self.impl_trait_ref(def_id);
2005 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2007 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2010 if is_marker_overlap {
2012 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2015 Some(ImplOverlapKind::Permitted { marker: true })
2017 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2018 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2019 if self_ty1 == self_ty2 {
2021 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2024 return Some(ImplOverlapKind::Issue33140);
2027 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2028 def_id1, def_id2, self_ty1, self_ty2
2034 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2039 /// Returns `ty::VariantDef` if `res` refers to a struct,
2040 /// or variant or their constructors, panics otherwise.
2041 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2043 Res::Def(DefKind::Variant, did) => {
2044 let enum_did = self.parent(did).unwrap();
2045 self.adt_def(enum_did).variant_with_id(did)
2047 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2048 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2049 let variant_did = self.parent(variant_ctor_did).unwrap();
2050 let enum_did = self.parent(variant_did).unwrap();
2051 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2053 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2054 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2055 self.adt_def(struct_did).non_enum_variant()
2057 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2061 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2062 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2064 ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
2067 | DefKind::AssocConst
2069 | DefKind::AnonConst
2070 | DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
2071 // If the caller wants `mir_for_ctfe` of a function they should not be using
2072 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2074 assert_eq!(def.const_param_did, None);
2075 self.optimized_mir(def.did)
2078 ty::InstanceDef::VtableShim(..)
2079 | ty::InstanceDef::ReifyShim(..)
2080 | ty::InstanceDef::Intrinsic(..)
2081 | ty::InstanceDef::FnPtrShim(..)
2082 | ty::InstanceDef::Virtual(..)
2083 | ty::InstanceDef::ClosureOnceShim { .. }
2084 | ty::InstanceDef::DropGlue(..)
2085 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2089 /// Gets the attributes of a definition.
2090 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
2091 if let Some(did) = did.as_local() {
2092 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2094 self.item_attrs(did)
2098 /// Determines whether an item is annotated with an attribute.
2099 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2100 self.sess.contains_name(&self.get_attrs(did), attr)
2103 /// Determines whether an item is annotated with `doc(hidden)`.
2104 pub fn is_doc_hidden(self, did: DefId) -> bool {
2107 .filter_map(|attr| if attr.has_name(sym::doc) { attr.meta_item_list() } else { None })
2108 .any(|items| items.iter().any(|item| item.has_name(sym::hidden)))
2111 /// Returns `true` if this is an `auto trait`.
2112 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2113 self.trait_def(trait_def_id).has_auto_impl
2116 /// Returns layout of a generator. Layout might be unavailable if the
2117 /// generator is tainted by errors.
2118 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2119 self.optimized_mir(def_id).generator_layout()
2122 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2123 /// If it implements no trait, returns `None`.
2124 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2125 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2128 /// If the given defid describes a method belonging to an impl, returns the
2129 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2130 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2131 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
2132 TraitContainer(_) => None,
2133 ImplContainer(def_id) => Some(def_id),
2137 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2138 /// with the name of the crate containing the impl.
2139 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2140 if let Some(impl_did) = impl_did.as_local() {
2141 Ok(self.def_span(impl_did))
2143 Err(self.crate_name(impl_did.krate))
2147 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2148 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2149 /// definition's parent/scope to perform comparison.
2150 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2151 // We could use `Ident::eq` here, but we deliberately don't. The name
2152 // comparison fails frequently, and we want to avoid the expensive
2153 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2154 use_name.name == def_name.name
2158 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2161 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2162 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2166 pub fn adjust_ident_and_get_scope(
2171 ) -> (Ident, DefId) {
2174 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2175 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2176 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2180 pub fn is_object_safe(self, key: DefId) -> bool {
2181 self.object_safety_violations(key).is_empty()
2185 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
2186 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
2187 let def_id = def_id.as_local()?;
2188 if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) {
2189 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2190 return match opaque_ty.origin {
2191 hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
2194 hir::OpaqueTyOrigin::TyAlias => None,
2201 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2203 ast::IntTy::Isize => IntTy::Isize,
2204 ast::IntTy::I8 => IntTy::I8,
2205 ast::IntTy::I16 => IntTy::I16,
2206 ast::IntTy::I32 => IntTy::I32,
2207 ast::IntTy::I64 => IntTy::I64,
2208 ast::IntTy::I128 => IntTy::I128,
2212 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2214 ast::UintTy::Usize => UintTy::Usize,
2215 ast::UintTy::U8 => UintTy::U8,
2216 ast::UintTy::U16 => UintTy::U16,
2217 ast::UintTy::U32 => UintTy::U32,
2218 ast::UintTy::U64 => UintTy::U64,
2219 ast::UintTy::U128 => UintTy::U128,
2223 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2225 ast::FloatTy::F32 => FloatTy::F32,
2226 ast::FloatTy::F64 => FloatTy::F64,
2230 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2232 IntTy::Isize => ast::IntTy::Isize,
2233 IntTy::I8 => ast::IntTy::I8,
2234 IntTy::I16 => ast::IntTy::I16,
2235 IntTy::I32 => ast::IntTy::I32,
2236 IntTy::I64 => ast::IntTy::I64,
2237 IntTy::I128 => ast::IntTy::I128,
2241 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2243 UintTy::Usize => ast::UintTy::Usize,
2244 UintTy::U8 => ast::UintTy::U8,
2245 UintTy::U16 => ast::UintTy::U16,
2246 UintTy::U32 => ast::UintTy::U32,
2247 UintTy::U64 => ast::UintTy::U64,
2248 UintTy::U128 => ast::UintTy::U128,
2252 pub fn provide(providers: &mut ty::query::Providers) {
2253 closure::provide(providers);
2254 context::provide(providers);
2255 erase_regions::provide(providers);
2256 layout::provide(providers);
2257 util::provide(providers);
2258 print::provide(providers);
2259 super::util::bug::provide(providers);
2260 super::middle::provide(providers);
2261 *providers = ty::query::Providers {
2262 trait_impls_of: trait_def::trait_impls_of_provider,
2263 type_uninhabited_from: inhabitedness::type_uninhabited_from,
2264 const_param_default: consts::const_param_default,
2265 vtable_allocation: vtable::vtable_allocation_provider,
2270 /// A map for the local crate mapping each type to a vector of its
2271 /// inherent impls. This is not meant to be used outside of coherence;
2272 /// rather, you should request the vector for a specific type via
2273 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2274 /// (constructing this map requires touching the entire crate).
2275 #[derive(Clone, Debug, Default, HashStable)]
2276 pub struct CrateInherentImpls {
2277 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2280 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2281 pub struct SymbolName<'tcx> {
2282 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2283 pub name: &'tcx str,
2286 impl<'tcx> SymbolName<'tcx> {
2287 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2289 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2294 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2295 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2296 fmt::Display::fmt(&self.name, fmt)
2300 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2301 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2302 fmt::Display::fmt(&self.name, fmt)
2306 #[derive(Debug, Default, Copy, Clone)]
2307 pub struct FoundRelationships {
2308 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2309 /// obligation, where:
2311 /// * `Foo` is not `Sized`
2312 /// * `(): Foo` may be satisfied
2313 pub self_in_trait: bool,
2314 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2315 /// _>::AssocType = ?T`