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::*;
20 use rustc_data_structures::fingerprint::Fingerprint;
23 use crate::metadata::ModChild;
24 use crate::middle::privacy::AccessLevels;
25 use crate::mir::{Body, GeneratorLayout};
26 use crate::traits::{self, Reveal};
28 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
29 use crate::ty::util::Discr;
31 use rustc_attr as attr;
32 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
33 use rustc_data_structures::intern::Interned;
34 use rustc_data_structures::stable_hasher::{HashStable, NodeIdHashingMode, StableHasher};
35 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
37 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
38 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap, CRATE_DEF_INDEX};
40 use rustc_macros::HashStable;
41 use rustc_query_system::ich::StableHashingContext;
42 use rustc_session::cstore::CrateStoreDyn;
43 use rustc_span::symbol::{kw, Ident, Symbol};
45 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, GeneratorInteriorTypeCause, GlobalCtxt,
70 Lift, OnDiskCache, TyCtxt, TypeckResults, UserType, UserTypeAnnotationIndex,
72 pub use self::instance::{Instance, InstanceDef};
73 pub use self::list::List;
74 pub use self::sty::BoundRegionKind::*;
75 pub use self::sty::RegionKind::*;
76 pub use self::sty::TyKind::*;
78 Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind,
79 CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBoundRegion,
80 ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig,
81 GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts, InlineConstSubstsParts, ParamConst,
82 ParamTy, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig,
83 PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut,
84 UpvarSubsts, VarianceDiagInfo,
86 pub use self::trait_def::TraitDef;
97 pub mod inhabitedness;
99 pub mod normalize_erasing_regions;
120 mod structural_impls;
125 pub type RegisteredTools = FxHashSet<Ident>;
128 pub struct ResolverOutputs {
129 pub definitions: rustc_hir::definitions::Definitions,
130 pub cstore: Box<CrateStoreDyn>,
131 pub visibilities: FxHashMap<LocalDefId, Visibility>,
132 pub access_levels: AccessLevels,
133 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
134 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
135 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
136 pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
137 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
138 /// Extern prelude entries. The value is `true` if the entry was introduced
139 /// via `extern crate` item and not `--extern` option or compiler built-in.
140 pub extern_prelude: FxHashMap<Symbol, bool>,
141 pub main_def: Option<MainDefinition>,
142 pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
143 /// A list of proc macro LocalDefIds, written out in the order in which
144 /// they are declared in the static array generated by proc_macro_harness.
145 pub proc_macros: Vec<LocalDefId>,
146 /// Mapping from ident span to path span for paths that don't exist as written, but that
147 /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
148 pub confused_type_with_std_module: FxHashMap<Span, Span>,
149 pub registered_tools: RegisteredTools,
152 #[derive(Clone, Copy, Debug)]
153 pub struct MainDefinition {
154 pub res: Res<ast::NodeId>,
159 impl MainDefinition {
160 pub fn opt_fn_def_id(self) -> Option<DefId> {
161 if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
165 /// The "header" of an impl is everything outside the body: a Self type, a trait
166 /// ref (in the case of a trait impl), and a set of predicates (from the
167 /// bounds / where-clauses).
168 #[derive(Clone, Debug, TypeFoldable)]
169 pub struct ImplHeader<'tcx> {
170 pub impl_def_id: DefId,
171 pub self_ty: Ty<'tcx>,
172 pub trait_ref: Option<TraitRef<'tcx>>,
173 pub predicates: Vec<Predicate<'tcx>>,
176 #[derive(Copy, Clone, Debug, TypeFoldable)]
177 pub enum ImplSubject<'tcx> {
178 Trait(TraitRef<'tcx>),
194 pub enum ImplPolarity {
195 /// `impl Trait for Type`
197 /// `impl !Trait for Type`
199 /// `#[rustc_reservation_impl] impl Trait for Type`
201 /// This is a "stability hack", not a real Rust feature.
202 /// See #64631 for details.
207 /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
208 pub fn flip(&self) -> Option<ImplPolarity> {
210 ImplPolarity::Positive => Some(ImplPolarity::Negative),
211 ImplPolarity::Negative => Some(ImplPolarity::Positive),
212 ImplPolarity::Reservation => None,
217 impl fmt::Display for ImplPolarity {
218 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
220 Self::Positive => f.write_str("positive"),
221 Self::Negative => f.write_str("negative"),
222 Self::Reservation => f.write_str("reservation"),
227 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
228 pub enum Visibility {
229 /// Visible everywhere (including in other crates).
231 /// Visible only in the given crate-local module.
233 /// Not visible anywhere in the local crate. This is the visibility of private external items.
237 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
238 pub enum BoundConstness {
241 /// `T: ~const Trait`
243 /// Requires resolving to const only when we are in a const context.
247 impl BoundConstness {
248 /// Reduce `self` and `constness` to two possible combined states instead of four.
249 pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
250 match (constness, self) {
251 (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
253 *this = BoundConstness::NotConst;
254 hir::Constness::NotConst
260 impl fmt::Display for BoundConstness {
261 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
263 Self::NotConst => f.write_str("normal"),
264 Self::ConstIfConst => f.write_str("`~const`"),
281 pub struct ClosureSizeProfileData<'tcx> {
282 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
283 pub before_feature_tys: Ty<'tcx>,
284 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
285 pub after_feature_tys: Ty<'tcx>,
288 pub trait DefIdTree: Copy {
289 fn parent(self, id: DefId) -> Option<DefId>;
291 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
292 if descendant.krate != ancestor.krate {
296 while descendant != ancestor {
297 match self.parent(descendant) {
298 Some(parent) => descendant = parent,
299 None => return false,
306 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
307 fn parent(self, id: DefId) -> Option<DefId> {
308 self.def_key(id).parent.map(|index| DefId { index, ..id })
313 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
314 match visibility.node {
315 hir::VisibilityKind::Public => Visibility::Public,
316 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
317 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
318 // If there is no resolution, `resolve` will have already reported an error, so
319 // assume that the visibility is public to avoid reporting more privacy errors.
320 Res::Err => Visibility::Public,
321 def => Visibility::Restricted(def.def_id()),
323 hir::VisibilityKind::Inherited => {
324 Visibility::Restricted(tcx.parent_module(id).to_def_id())
329 /// Returns `true` if an item with this visibility is accessible from the given block.
330 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
331 let restriction = match self {
332 // Public items are visible everywhere.
333 Visibility::Public => return true,
334 // Private items from other crates are visible nowhere.
335 Visibility::Invisible => return false,
336 // Restricted items are visible in an arbitrary local module.
337 Visibility::Restricted(other) if other.krate != module.krate => return false,
338 Visibility::Restricted(module) => module,
341 tree.is_descendant_of(module, restriction)
344 /// Returns `true` if this visibility is at least as accessible as the given visibility
345 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
346 let vis_restriction = match vis {
347 Visibility::Public => return self == Visibility::Public,
348 Visibility::Invisible => return true,
349 Visibility::Restricted(module) => module,
352 self.is_accessible_from(vis_restriction, tree)
355 // Returns `true` if this item is visible anywhere in the local crate.
356 pub fn is_visible_locally(self) -> bool {
358 Visibility::Public => true,
359 Visibility::Restricted(def_id) => def_id.is_local(),
360 Visibility::Invisible => false,
364 pub fn is_public(self) -> bool {
365 matches!(self, Visibility::Public)
369 /// The crate variances map is computed during typeck and contains the
370 /// variance of every item in the local crate. You should not use it
371 /// directly, because to do so will make your pass dependent on the
372 /// HIR of every item in the local crate. Instead, use
373 /// `tcx.variances_of()` to get the variance for a *particular*
375 #[derive(HashStable, Debug)]
376 pub struct CrateVariancesMap<'tcx> {
377 /// For each item with generics, maps to a vector of the variance
378 /// of its generics. If an item has no generics, it will have no
380 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
383 // Contains information needed to resolve types and (in the future) look up
384 // the types of AST nodes.
385 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
386 pub struct CReaderCacheKey {
387 pub cnum: Option<CrateNum>,
391 /// Represents a type.
394 /// - This is a very "dumb" struct (with no derives and no `impls`).
395 /// - Values of this type are always interned and thus unique, and are stored
396 /// as an `Interned<TyS>`.
397 /// - `Ty` (which contains a reference to a `Interned<TyS>`) or `Interned<TyS>`
398 /// should be used everywhere instead of `TyS`. In particular, `Ty` has most
399 /// of the relevant methods.
400 #[derive(PartialEq, Eq, PartialOrd, Ord)]
401 #[allow(rustc::usage_of_ty_tykind)]
402 crate struct TyS<'tcx> {
403 /// This field shouldn't be used directly and may be removed in the future.
404 /// Use `Ty::kind()` instead.
407 /// This field provides fast access to information that is also contained
410 /// This field shouldn't be used directly and may be removed in the future.
411 /// Use `Ty::flags()` instead.
414 /// This field provides fast access to information that is also contained
417 /// This is a kind of confusing thing: it stores the smallest
420 /// (a) the binder itself captures nothing but
421 /// (b) all the late-bound things within the type are captured
422 /// by some sub-binder.
424 /// So, for a type without any late-bound things, like `u32`, this
425 /// will be *innermost*, because that is the innermost binder that
426 /// captures nothing. But for a type `&'D u32`, where `'D` is a
427 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
428 /// -- the binder itself does not capture `D`, but `D` is captured
429 /// by an inner binder.
431 /// We call this concept an "exclusive" binder `D` because all
432 /// De Bruijn indices within the type are contained within `0..D`
434 outer_exclusive_binder: ty::DebruijnIndex,
436 /// The stable hash of the type. This way hashing of types will not have to work
437 /// on the address of the type anymore, but can instead just read this field
438 stable_hash: Fingerprint,
441 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
442 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
443 static_assert_size!(TyS<'_>, 56);
445 /// Use this rather than `TyS`, whenever possible.
446 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
447 #[rustc_diagnostic_item = "Ty"]
448 #[rustc_pass_by_value]
449 pub struct Ty<'tcx>(Interned<'tcx, TyS<'tcx>>);
451 // Statics only used for internal testing.
452 pub static BOOL_TY: Ty<'static> = Ty(Interned::new_unchecked(&BOOL_TYS));
453 static BOOL_TYS: TyS<'static> = TyS {
455 flags: TypeFlags::empty(),
456 outer_exclusive_binder: DebruijnIndex::from_usize(0),
457 stable_hash: Fingerprint::ZERO,
460 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Ty<'tcx> {
461 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
465 // The other fields just provide fast access to information that is
466 // also contained in `kind`, so no need to hash them.
469 outer_exclusive_binder: _,
474 if *stable_hash == Fingerprint::ZERO {
475 // No cached hash available. This can only mean that incremental is disabled.
476 // We don't cache stable hashes in non-incremental mode, because they are used
477 // so rarely that the performance actually suffers.
479 let stable_hash: Fingerprint = {
480 let mut hasher = StableHasher::new();
481 hcx.while_hashing_spans(false, |hcx| {
482 hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
483 kind.hash_stable(hcx, &mut hasher)
488 stable_hash.hash_stable(hcx, hasher);
490 stable_hash.hash_stable(hcx, hasher);
495 impl ty::EarlyBoundRegion {
496 /// Does this early bound region have a name? Early bound regions normally
497 /// always have names except when using anonymous lifetimes (`'_`).
498 pub fn has_name(&self) -> bool {
499 self.name != kw::UnderscoreLifetime
503 /// Represents a predicate.
505 /// See comments on `TyS`, which apply here too (albeit for
506 /// `PredicateS`/`Predicate` rather than `TyS`/`Ty`).
508 crate struct PredicateS<'tcx> {
509 kind: Binder<'tcx, PredicateKind<'tcx>>,
511 /// See the comment for the corresponding field of [TyS].
512 outer_exclusive_binder: ty::DebruijnIndex,
515 // This type is used a lot. Make sure it doesn't unintentionally get bigger.
516 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
517 static_assert_size!(PredicateS<'_>, 56);
519 /// Use this rather than `PredicateS`, whenever possible.
520 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
521 #[rustc_pass_by_value]
522 pub struct Predicate<'tcx>(Interned<'tcx, PredicateS<'tcx>>);
524 impl<'tcx> Predicate<'tcx> {
525 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
527 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
532 pub fn flags(self) -> TypeFlags {
537 pub fn outer_exclusive_binder(self) -> DebruijnIndex {
538 self.0.outer_exclusive_binder
541 /// Flips the polarity of a Predicate.
543 /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
544 pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
547 .map_bound(|kind| match kind {
548 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
549 Some(PredicateKind::Trait(TraitPredicate {
552 polarity: polarity.flip()?,
560 Some(tcx.mk_predicate(kind))
564 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
565 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
569 // The other fields just provide fast access to information that is
570 // also contained in `kind`, so no need to hash them.
572 outer_exclusive_binder: _,
575 kind.hash_stable(hcx, hasher);
579 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
580 #[derive(HashStable, TypeFoldable)]
581 pub enum PredicateKind<'tcx> {
582 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
583 /// the `Self` type of the trait reference and `A`, `B`, and `C`
584 /// would be the type parameters.
585 Trait(TraitPredicate<'tcx>),
588 RegionOutlives(RegionOutlivesPredicate<'tcx>),
591 TypeOutlives(TypeOutlivesPredicate<'tcx>),
593 /// `where <T as TraitRef>::Name == X`, approximately.
594 /// See the `ProjectionPredicate` struct for details.
595 Projection(ProjectionPredicate<'tcx>),
597 /// No syntax: `T` well-formed.
598 WellFormed(GenericArg<'tcx>),
600 /// Trait must be object-safe.
603 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
604 /// for some substitutions `...` and `T` being a closure type.
605 /// Satisfied (or refuted) once we know the closure's kind.
606 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
610 /// This obligation is created most often when we have two
611 /// unresolved type variables and hence don't have enough
612 /// information to process the subtyping obligation yet.
613 Subtype(SubtypePredicate<'tcx>),
615 /// `T1` coerced to `T2`
617 /// Like a subtyping obligation, this is created most often
618 /// when we have two unresolved type variables and hence
619 /// don't have enough information to process the coercion
620 /// obligation yet. At the moment, we actually process coercions
621 /// very much like subtyping and don't handle the full coercion
623 Coerce(CoercePredicate<'tcx>),
625 /// Constant initializer must evaluate successfully.
626 ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
628 /// Constants must be equal. The first component is the const that is expected.
629 ConstEquate(Const<'tcx>, Const<'tcx>),
631 /// Represents a type found in the environment that we can use for implied bounds.
633 /// Only used for Chalk.
634 TypeWellFormedFromEnv(Ty<'tcx>),
637 /// The crate outlives map is computed during typeck and contains the
638 /// outlives of every item in the local crate. You should not use it
639 /// directly, because to do so will make your pass dependent on the
640 /// HIR of every item in the local crate. Instead, use
641 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
643 #[derive(HashStable, Debug)]
644 pub struct CratePredicatesMap<'tcx> {
645 /// For each struct with outlive bounds, maps to a vector of the
646 /// predicate of its outlive bounds. If an item has no outlives
647 /// bounds, it will have no entry.
648 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
651 impl<'tcx> Predicate<'tcx> {
652 /// Performs a substitution suitable for going from a
653 /// poly-trait-ref to supertraits that must hold if that
654 /// poly-trait-ref holds. This is slightly different from a normal
655 /// substitution in terms of what happens with bound regions. See
656 /// lengthy comment below for details.
657 pub fn subst_supertrait(
660 trait_ref: &ty::PolyTraitRef<'tcx>,
661 ) -> Predicate<'tcx> {
662 // The interaction between HRTB and supertraits is not entirely
663 // obvious. Let me walk you (and myself) through an example.
665 // Let's start with an easy case. Consider two traits:
667 // trait Foo<'a>: Bar<'a,'a> { }
668 // trait Bar<'b,'c> { }
670 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
671 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
672 // knew that `Foo<'x>` (for any 'x) then we also know that
673 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
674 // normal substitution.
676 // In terms of why this is sound, the idea is that whenever there
677 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
678 // holds. So if there is an impl of `T:Foo<'a>` that applies to
679 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
682 // Another example to be careful of is this:
684 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
685 // trait Bar1<'b,'c> { }
687 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
688 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
689 // reason is similar to the previous example: any impl of
690 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
691 // basically we would want to collapse the bound lifetimes from
692 // the input (`trait_ref`) and the supertraits.
694 // To achieve this in practice is fairly straightforward. Let's
695 // consider the more complicated scenario:
697 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
698 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
699 // where both `'x` and `'b` would have a DB index of 1.
700 // The substitution from the input trait-ref is therefore going to be
701 // `'a => 'x` (where `'x` has a DB index of 1).
702 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
703 // early-bound parameter and `'b' is a late-bound parameter with a
705 // - If we replace `'a` with `'x` from the input, it too will have
706 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
707 // just as we wanted.
709 // There is only one catch. If we just apply the substitution `'a
710 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
711 // adjust the DB index because we substituting into a binder (it
712 // tries to be so smart...) resulting in `for<'x> for<'b>
713 // Bar1<'x,'b>` (we have no syntax for this, so use your
714 // imagination). Basically the 'x will have DB index of 2 and 'b
715 // will have DB index of 1. Not quite what we want. So we apply
716 // the substitution to the *contents* of the trait reference,
717 // rather than the trait reference itself (put another way, the
718 // substitution code expects equal binding levels in the values
719 // from the substitution and the value being substituted into, and
720 // this trick achieves that).
722 // Working through the second example:
723 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
724 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
725 // We want to end up with:
726 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
728 // 1) We must shift all bound vars in predicate by the length
729 // of trait ref's bound vars. So, we would end up with predicate like
730 // Self: Bar1<'a, '^0.1>
731 // 2) We can then apply the trait substs to this, ending up with
732 // T: Bar1<'^0.0, '^0.1>
733 // 3) Finally, to create the final bound vars, we concatenate the bound
734 // vars of the trait ref with those of the predicate:
736 let bound_pred = self.kind();
737 let pred_bound_vars = bound_pred.bound_vars();
738 let trait_bound_vars = trait_ref.bound_vars();
739 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
741 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
742 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
743 let new = shifted_pred.subst(tcx, trait_ref.skip_binder().substs);
744 // 3) ['x] + ['b] -> ['x, 'b]
746 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
747 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
751 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
752 #[derive(HashStable, TypeFoldable)]
753 pub struct TraitPredicate<'tcx> {
754 pub trait_ref: TraitRef<'tcx>,
756 pub constness: BoundConstness,
758 /// If polarity is Positive: we are proving that the trait is implemented.
760 /// If polarity is Negative: we are proving that a negative impl of this trait
761 /// exists. (Note that coherence also checks whether negative impls of supertraits
762 /// exist via a series of predicates.)
764 /// If polarity is Reserved: that's a bug.
765 pub polarity: ImplPolarity,
768 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
770 impl<'tcx> TraitPredicate<'tcx> {
771 pub fn remap_constness(&mut self, tcx: TyCtxt<'tcx>, param_env: &mut ParamEnv<'tcx>) {
772 if unlikely!(Some(self.trait_ref.def_id) == tcx.lang_items().drop_trait()) {
773 // remap without changing constness of this predicate.
774 // this is because `T: ~const Drop` has a different meaning to `T: Drop`
775 // FIXME(fee1-dead): remove this logic after beta bump
776 param_env.remap_constness_with(self.constness)
778 *param_env = param_env.with_constness(self.constness.and(param_env.constness()))
782 /// Remap the constness of this predicate before emitting it for diagnostics.
783 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
784 // this is different to `remap_constness` that callees want to print this predicate
785 // in case of selection errors. `T: ~const Drop` bounds cannot end up here when the
786 // param_env is not const because we it is always satisfied in non-const contexts.
787 if let hir::Constness::NotConst = param_env.constness() {
788 self.constness = ty::BoundConstness::NotConst;
792 pub fn def_id(self) -> DefId {
793 self.trait_ref.def_id
796 pub fn self_ty(self) -> Ty<'tcx> {
797 self.trait_ref.self_ty()
801 pub fn is_const_if_const(self) -> bool {
802 self.constness == BoundConstness::ConstIfConst
806 impl<'tcx> PolyTraitPredicate<'tcx> {
807 pub fn def_id(self) -> DefId {
808 // Ok to skip binder since trait `DefId` does not care about regions.
809 self.skip_binder().def_id()
812 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
813 self.map_bound(|trait_ref| trait_ref.self_ty())
816 /// Remap the constness of this predicate before emitting it for diagnostics.
817 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
818 *self = self.map_bound(|mut p| {
819 p.remap_constness_diag(param_env);
825 pub fn is_const_if_const(self) -> bool {
826 self.skip_binder().is_const_if_const()
830 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
831 #[derive(HashStable, TypeFoldable)]
832 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
833 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
834 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
835 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
836 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
838 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
839 /// whether the `a` type is the type that we should label as "expected" when
840 /// presenting user diagnostics.
841 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
842 #[derive(HashStable, TypeFoldable)]
843 pub struct SubtypePredicate<'tcx> {
844 pub a_is_expected: bool,
848 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
850 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
851 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
852 #[derive(HashStable, TypeFoldable)]
853 pub struct CoercePredicate<'tcx> {
857 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
859 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)]
860 #[derive(HashStable, TypeFoldable)]
861 pub enum Term<'tcx> {
866 impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
867 fn from(ty: Ty<'tcx>) -> Self {
872 impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
873 fn from(c: Const<'tcx>) -> Self {
878 impl<'tcx> Term<'tcx> {
879 pub fn ty(&self) -> Option<Ty<'tcx>> {
880 if let Term::Ty(ty) = self { Some(*ty) } else { None }
882 pub fn ct(&self) -> Option<Const<'tcx>> {
883 if let Term::Const(c) = self { Some(*c) } else { None }
887 /// This kind of predicate has no *direct* correspondent in the
888 /// syntax, but it roughly corresponds to the syntactic forms:
890 /// 1. `T: TraitRef<..., Item = Type>`
891 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
893 /// In particular, form #1 is "desugared" to the combination of a
894 /// normal trait predicate (`T: TraitRef<...>`) and one of these
895 /// predicates. Form #2 is a broader form in that it also permits
896 /// equality between arbitrary types. Processing an instance of
897 /// Form #2 eventually yields one of these `ProjectionPredicate`
898 /// instances to normalize the LHS.
899 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
900 #[derive(HashStable, TypeFoldable)]
901 pub struct ProjectionPredicate<'tcx> {
902 pub projection_ty: ProjectionTy<'tcx>,
903 pub term: Term<'tcx>,
906 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
908 impl<'tcx> PolyProjectionPredicate<'tcx> {
909 /// Returns the `DefId` of the trait of the associated item being projected.
911 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
912 self.skip_binder().projection_ty.trait_def_id(tcx)
915 /// Get the [PolyTraitRef] required for this projection to be well formed.
916 /// Note that for generic associated types the predicates of the associated
917 /// type also need to be checked.
919 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
920 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
921 // `self.0.trait_ref` is permitted to have escaping regions.
922 // This is because here `self` has a `Binder` and so does our
923 // return value, so we are preserving the number of binding
925 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
928 pub fn term(&self) -> Binder<'tcx, Term<'tcx>> {
929 self.map_bound(|predicate| predicate.term)
932 /// The `DefId` of the `TraitItem` for the associated type.
934 /// Note that this is not the `DefId` of the `TraitRef` containing this
935 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
936 pub fn projection_def_id(&self) -> DefId {
937 // Ok to skip binder since trait `DefId` does not care about regions.
938 self.skip_binder().projection_ty.item_def_id
942 pub trait ToPolyTraitRef<'tcx> {
943 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
946 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
947 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
948 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
952 pub trait ToPredicate<'tcx> {
953 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
956 impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
958 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
959 tcx.mk_predicate(self)
963 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
964 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
965 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
969 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
970 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
971 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
975 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
976 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
977 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
981 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
982 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
983 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
987 impl<'tcx> Predicate<'tcx> {
988 pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
989 let predicate = self.kind();
990 match predicate.skip_binder() {
991 PredicateKind::Trait(t) => Some(predicate.rebind(t)),
992 PredicateKind::Projection(..)
993 | PredicateKind::Subtype(..)
994 | PredicateKind::Coerce(..)
995 | PredicateKind::RegionOutlives(..)
996 | PredicateKind::WellFormed(..)
997 | PredicateKind::ObjectSafe(..)
998 | PredicateKind::ClosureKind(..)
999 | PredicateKind::TypeOutlives(..)
1000 | PredicateKind::ConstEvaluatable(..)
1001 | PredicateKind::ConstEquate(..)
1002 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1006 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1007 let predicate = self.kind();
1008 match predicate.skip_binder() {
1009 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
1010 PredicateKind::Trait(..)
1011 | PredicateKind::Projection(..)
1012 | PredicateKind::Subtype(..)
1013 | PredicateKind::Coerce(..)
1014 | PredicateKind::RegionOutlives(..)
1015 | PredicateKind::WellFormed(..)
1016 | PredicateKind::ObjectSafe(..)
1017 | PredicateKind::ClosureKind(..)
1018 | PredicateKind::ConstEvaluatable(..)
1019 | PredicateKind::ConstEquate(..)
1020 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1025 /// Represents the bounds declared on a particular set of type
1026 /// parameters. Should eventually be generalized into a flag list of
1027 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
1028 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1029 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1030 /// the `GenericPredicates` are expressed in terms of the bound type
1031 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1032 /// represented a set of bounds for some particular instantiation,
1033 /// meaning that the generic parameters have been substituted with
1038 /// struct Foo<T, U: Bar<T>> { ... }
1040 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1041 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1042 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1043 /// [usize:Bar<isize>]]`.
1044 #[derive(Clone, Debug, TypeFoldable)]
1045 pub struct InstantiatedPredicates<'tcx> {
1046 pub predicates: Vec<Predicate<'tcx>>,
1047 pub spans: Vec<Span>,
1050 impl<'tcx> InstantiatedPredicates<'tcx> {
1051 pub fn empty() -> InstantiatedPredicates<'tcx> {
1052 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1055 pub fn is_empty(&self) -> bool {
1056 self.predicates.is_empty()
1060 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable, TypeFoldable)]
1061 pub struct OpaqueTypeKey<'tcx> {
1063 pub substs: SubstsRef<'tcx>,
1066 rustc_index::newtype_index! {
1067 /// "Universes" are used during type- and trait-checking in the
1068 /// presence of `for<..>` binders to control what sets of names are
1069 /// visible. Universes are arranged into a tree: the root universe
1070 /// contains names that are always visible. Each child then adds a new
1071 /// set of names that are visible, in addition to those of its parent.
1072 /// We say that the child universe "extends" the parent universe with
1075 /// To make this more concrete, consider this program:
1079 /// fn bar<T>(x: T) {
1080 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1084 /// The struct name `Foo` is in the root universe U0. But the type
1085 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1086 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1087 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1088 /// region `'a` is in a universe U2 that extends U1, because we can
1089 /// name it inside the fn type but not outside.
1091 /// Universes are used to do type- and trait-checking around these
1092 /// "forall" binders (also called **universal quantification**). The
1093 /// idea is that when, in the body of `bar`, we refer to `T` as a
1094 /// type, we aren't referring to any type in particular, but rather a
1095 /// kind of "fresh" type that is distinct from all other types we have
1096 /// actually declared. This is called a **placeholder** type, and we
1097 /// use universes to talk about this. In other words, a type name in
1098 /// universe 0 always corresponds to some "ground" type that the user
1099 /// declared, but a type name in a non-zero universe is a placeholder
1100 /// type -- an idealized representative of "types in general" that we
1101 /// use for checking generic functions.
1102 pub struct UniverseIndex {
1104 DEBUG_FORMAT = "U{}",
1108 impl UniverseIndex {
1109 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1111 /// Returns the "next" universe index in order -- this new index
1112 /// is considered to extend all previous universes. This
1113 /// corresponds to entering a `forall` quantifier. So, for
1114 /// example, suppose we have this type in universe `U`:
1117 /// for<'a> fn(&'a u32)
1120 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1121 /// new universe that extends `U` -- in this new universe, we can
1122 /// name the region `'a`, but that region was not nameable from
1123 /// `U` because it was not in scope there.
1124 pub fn next_universe(self) -> UniverseIndex {
1125 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1128 /// Returns `true` if `self` can name a name from `other` -- in other words,
1129 /// if the set of names in `self` is a superset of those in
1130 /// `other` (`self >= other`).
1131 pub fn can_name(self, other: UniverseIndex) -> bool {
1132 self.private >= other.private
1135 /// Returns `true` if `self` cannot name some names from `other` -- in other
1136 /// words, if the set of names in `self` is a strict subset of
1137 /// those in `other` (`self < other`).
1138 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1139 self.private < other.private
1143 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1144 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1145 /// regions/types/consts within the same universe simply have an unknown relationship to one
1147 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1148 pub struct Placeholder<T> {
1149 pub universe: UniverseIndex,
1153 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1155 T: HashStable<StableHashingContext<'a>>,
1157 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1158 self.universe.hash_stable(hcx, hasher);
1159 self.name.hash_stable(hcx, hasher);
1163 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1165 pub type PlaceholderType = Placeholder<BoundVar>;
1167 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1168 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1169 pub struct BoundConst<'tcx> {
1174 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1176 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1177 /// the `DefId` of the generic parameter it instantiates.
1179 /// This is used to avoid calls to `type_of` for const arguments during typeck
1180 /// which cause cycle errors.
1185 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1186 /// // ^ const parameter
1190 /// fn foo<const M: u8>(&self) -> usize { 42 }
1191 /// // ^ const parameter
1196 /// let _b = a.foo::<{ 3 + 7 }>();
1197 /// // ^^^^^^^^^ const argument
1201 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1202 /// which `foo` is used until we know the type of `a`.
1204 /// We only know the type of `a` once we are inside of `typeck(main)`.
1205 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1206 /// requires us to evaluate the const argument.
1208 /// To evaluate that const argument we need to know its type,
1209 /// which we would get using `type_of(const_arg)`. This requires us to
1210 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1211 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1212 /// which results in a cycle.
1214 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1216 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1217 /// already resolved `foo` so we know which const parameter this argument instantiates.
1218 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1219 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1220 /// trivial to compute.
1222 /// If we now want to use that constant in a place which potentionally needs its type
1223 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1224 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1225 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1226 /// to get the type of `did`.
1227 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1228 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1229 #[derive(Hash, HashStable)]
1230 pub struct WithOptConstParam<T> {
1232 /// The `DefId` of the corresponding generic parameter in case `did` is
1233 /// a const argument.
1235 /// Note that even if `did` is a const argument, this may still be `None`.
1236 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1237 /// to potentially update `param_did` in the case it is `None`.
1238 pub const_param_did: Option<DefId>,
1241 impl<T> WithOptConstParam<T> {
1242 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1244 pub fn unknown(did: T) -> WithOptConstParam<T> {
1245 WithOptConstParam { did, const_param_did: None }
1249 impl WithOptConstParam<LocalDefId> {
1250 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1251 /// `None` otherwise.
1253 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1254 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1257 /// In case `self` is unknown but `self.did` is a const argument, this returns
1258 /// a `WithOptConstParam` with the correct `const_param_did`.
1260 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1261 if self.const_param_did.is_none() {
1262 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1263 return Some(WithOptConstParam { did: self.did, const_param_did });
1270 pub fn to_global(self) -> WithOptConstParam<DefId> {
1271 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1274 pub fn def_id_for_type_of(self) -> DefId {
1275 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1279 impl WithOptConstParam<DefId> {
1280 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1283 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1286 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1287 if let Some(param_did) = self.const_param_did {
1288 if let Some(did) = self.did.as_local() {
1289 return Some((did, param_did));
1296 pub fn is_local(self) -> bool {
1300 pub fn def_id_for_type_of(self) -> DefId {
1301 self.const_param_did.unwrap_or(self.did)
1305 /// When type checking, we use the `ParamEnv` to track
1306 /// details about the set of where-clauses that are in scope at this
1307 /// particular point.
1308 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1309 pub struct ParamEnv<'tcx> {
1310 /// This packs both caller bounds and the reveal enum into one pointer.
1312 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1313 /// basically the set of bounds on the in-scope type parameters, translated
1314 /// into `Obligation`s, and elaborated and normalized.
1316 /// Use the `caller_bounds()` method to access.
1318 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1319 /// want `Reveal::All`.
1321 /// Note: This is packed, use the reveal() method to access it.
1322 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
1325 #[derive(Copy, Clone)]
1327 reveal: traits::Reveal,
1328 constness: hir::Constness,
1331 unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
1332 const BITS: usize = 2;
1334 fn into_usize(self) -> usize {
1336 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
1337 Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
1338 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
1339 Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
1343 unsafe fn from_usize(ptr: usize) -> Self {
1345 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1346 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
1347 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
1348 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
1349 _ => std::hint::unreachable_unchecked(),
1354 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1355 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1356 f.debug_struct("ParamEnv")
1357 .field("caller_bounds", &self.caller_bounds())
1358 .field("reveal", &self.reveal())
1359 .field("constness", &self.constness())
1364 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1365 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1366 self.caller_bounds().hash_stable(hcx, hasher);
1367 self.reveal().hash_stable(hcx, hasher);
1368 self.constness().hash_stable(hcx, hasher);
1372 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1373 fn try_super_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
1376 ) -> Result<Self, F::Error> {
1378 self.caller_bounds().try_fold_with(folder)?,
1379 self.reveal().try_fold_with(folder)?,
1380 self.constness().try_fold_with(folder)?,
1384 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1385 self.caller_bounds().visit_with(visitor)?;
1386 self.reveal().visit_with(visitor)?;
1387 self.constness().visit_with(visitor)
1391 impl<'tcx> ParamEnv<'tcx> {
1392 /// Construct a trait environment suitable for contexts where
1393 /// there are no where-clauses in scope. Hidden types (like `impl
1394 /// Trait`) are left hidden, so this is suitable for ordinary
1397 pub fn empty() -> Self {
1398 Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
1402 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1403 self.packed.pointer()
1407 pub fn reveal(self) -> traits::Reveal {
1408 self.packed.tag().reveal
1412 pub fn constness(self) -> hir::Constness {
1413 self.packed.tag().constness
1417 pub fn is_const(self) -> bool {
1418 self.packed.tag().constness == hir::Constness::Const
1421 /// Construct a trait environment with no where-clauses in scope
1422 /// where the values of all `impl Trait` and other hidden types
1423 /// are revealed. This is suitable for monomorphized, post-typeck
1424 /// environments like codegen or doing optimizations.
1426 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1427 /// or invoke `param_env.with_reveal_all()`.
1429 pub fn reveal_all() -> Self {
1430 Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
1433 /// Construct a trait environment with the given set of predicates.
1436 caller_bounds: &'tcx List<Predicate<'tcx>>,
1438 constness: hir::Constness,
1440 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
1443 pub fn with_user_facing(mut self) -> Self {
1444 self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
1449 pub fn with_constness(mut self, constness: hir::Constness) -> Self {
1450 self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
1455 pub fn with_const(mut self) -> Self {
1456 self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
1461 pub fn without_const(mut self) -> Self {
1462 self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
1467 pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
1468 *self = self.with_constness(constness.and(self.constness()))
1471 /// Returns a new parameter environment with the same clauses, but
1472 /// which "reveals" the true results of projections in all cases
1473 /// (even for associated types that are specializable). This is
1474 /// the desired behavior during codegen and certain other special
1475 /// contexts; normally though we want to use `Reveal::UserFacing`,
1476 /// which is the default.
1477 /// All opaque types in the caller_bounds of the `ParamEnv`
1478 /// will be normalized to their underlying types.
1479 /// See PR #65989 and issue #65918 for more details
1480 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1481 if self.packed.tag().reveal == traits::Reveal::All {
1486 tcx.normalize_opaque_types(self.caller_bounds()),
1492 /// Returns this same environment but with no caller bounds.
1494 pub fn without_caller_bounds(self) -> Self {
1495 Self::new(List::empty(), self.reveal(), self.constness())
1498 /// Creates a suitable environment in which to perform trait
1499 /// queries on the given value. When type-checking, this is simply
1500 /// the pair of the environment plus value. But when reveal is set to
1501 /// All, then if `value` does not reference any type parameters, we will
1502 /// pair it with the empty environment. This improves caching and is generally
1505 /// N.B., we preserve the environment when type-checking because it
1506 /// is possible for the user to have wacky where-clauses like
1507 /// `where Box<u32>: Copy`, which are clearly never
1508 /// satisfiable. We generally want to behave as if they were true,
1509 /// although the surrounding function is never reachable.
1510 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1511 match self.reveal() {
1512 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1515 if value.is_global() {
1516 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1518 ParamEnvAnd { param_env: self, value }
1525 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1526 // the constness of trait bounds is being propagated correctly.
1527 impl<'tcx> PolyTraitRef<'tcx> {
1529 pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
1530 self.map_bound(|trait_ref| ty::TraitPredicate {
1533 polarity: ty::ImplPolarity::Positive,
1538 pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
1539 self.with_constness(BoundConstness::NotConst)
1543 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1544 pub struct ParamEnvAnd<'tcx, T> {
1545 pub param_env: ParamEnv<'tcx>,
1549 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1550 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1551 (self.param_env, self.value)
1555 pub fn without_const(mut self) -> Self {
1556 self.param_env = self.param_env.without_const();
1561 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1563 T: HashStable<StableHashingContext<'a>>,
1565 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1566 let ParamEnvAnd { ref param_env, ref value } = *self;
1568 param_env.hash_stable(hcx, hasher);
1569 value.hash_stable(hcx, hasher);
1573 #[derive(Copy, Clone, Debug, HashStable)]
1574 pub struct Destructor {
1575 /// The `DefId` of the destructor method
1577 /// The constness of the destructor method
1578 pub constness: hir::Constness,
1582 #[derive(HashStable, TyEncodable, TyDecodable)]
1583 pub struct VariantFlags: u32 {
1584 const NO_VARIANT_FLAGS = 0;
1585 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1586 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1587 /// Indicates whether this variant was obtained as part of recovering from
1588 /// a syntactic error. May be incomplete or bogus.
1589 const IS_RECOVERED = 1 << 1;
1593 /// Definition of a variant -- a struct's fields or an enum variant.
1594 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1595 pub struct VariantDef {
1596 /// `DefId` that identifies the variant itself.
1597 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1599 /// `DefId` that identifies the variant's constructor.
1600 /// If this variant is a struct variant, then this is `None`.
1601 pub ctor_def_id: Option<DefId>,
1602 /// Variant or struct name.
1604 /// Discriminant of this variant.
1605 pub discr: VariantDiscr,
1606 /// Fields of this variant.
1607 pub fields: Vec<FieldDef>,
1608 /// Type of constructor of variant.
1609 pub ctor_kind: CtorKind,
1610 /// Flags of the variant (e.g. is field list non-exhaustive)?
1611 flags: VariantFlags,
1615 /// Creates a new `VariantDef`.
1617 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1618 /// represents an enum variant).
1620 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1621 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1623 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1624 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1625 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1626 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1627 /// built-in trait), and we do not want to load attributes twice.
1629 /// If someone speeds up attribute loading to not be a performance concern, they can
1630 /// remove this hack and use the constructor `DefId` everywhere.
1633 variant_did: Option<DefId>,
1634 ctor_def_id: Option<DefId>,
1635 discr: VariantDiscr,
1636 fields: Vec<FieldDef>,
1637 ctor_kind: CtorKind,
1641 is_field_list_non_exhaustive: bool,
1644 "VariantDef::new(name = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1645 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1646 name, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1649 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1650 if is_field_list_non_exhaustive {
1651 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1655 flags |= VariantFlags::IS_RECOVERED;
1659 def_id: variant_did.unwrap_or(parent_did),
1669 /// Is this field list non-exhaustive?
1671 pub fn is_field_list_non_exhaustive(&self) -> bool {
1672 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1675 /// Was this variant obtained as part of recovering from a syntactic error?
1677 pub fn is_recovered(&self) -> bool {
1678 self.flags.intersects(VariantFlags::IS_RECOVERED)
1681 /// Computes the `Ident` of this variant by looking up the `Span`
1682 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1683 Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1687 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1688 pub enum VariantDiscr {
1689 /// Explicit value for this variant, i.e., `X = 123`.
1690 /// The `DefId` corresponds to the embedded constant.
1693 /// The previous variant's discriminant plus one.
1694 /// For efficiency reasons, the distance from the
1695 /// last `Explicit` discriminant is being stored,
1696 /// or `0` for the first variant, if it has none.
1700 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1701 pub struct FieldDef {
1704 pub vis: Visibility,
1708 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1709 pub struct ReprFlags: u8 {
1710 const IS_C = 1 << 0;
1711 const IS_SIMD = 1 << 1;
1712 const IS_TRANSPARENT = 1 << 2;
1713 // Internal only for now. If true, don't reorder fields.
1714 const IS_LINEAR = 1 << 3;
1715 // If true, don't expose any niche to type's context.
1716 const HIDE_NICHE = 1 << 4;
1717 // If true, the type's layout can be randomized using
1718 // the seed stored in `ReprOptions.layout_seed`
1719 const RANDOMIZE_LAYOUT = 1 << 5;
1720 // Any of these flags being set prevent field reordering optimisation.
1721 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
1722 | ReprFlags::IS_SIMD.bits
1723 | ReprFlags::IS_LINEAR.bits;
1727 /// Represents the repr options provided by the user,
1728 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
1729 pub struct ReprOptions {
1730 pub int: Option<attr::IntType>,
1731 pub align: Option<Align>,
1732 pub pack: Option<Align>,
1733 pub flags: ReprFlags,
1734 /// The seed to be used for randomizing a type's layout
1736 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
1737 /// be the "most accurate" hash as it'd encompass the item and crate
1738 /// hash without loss, but it does pay the price of being larger.
1739 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
1740 /// purposes (primarily `-Z randomize-layout`)
1741 pub field_shuffle_seed: u64,
1745 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1746 let mut flags = ReprFlags::empty();
1747 let mut size = None;
1748 let mut max_align: Option<Align> = None;
1749 let mut min_pack: Option<Align> = None;
1751 // Generate a deterministically-derived seed from the item's path hash
1752 // to allow for cross-crate compilation to actually work
1753 let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
1755 // If the user defined a custom seed for layout randomization, xor the item's
1756 // path hash with the user defined seed, this will allowing determinism while
1757 // still allowing users to further randomize layout generation for e.g. fuzzing
1758 if let Some(user_seed) = tcx.sess.opts.debugging_opts.layout_seed {
1759 field_shuffle_seed ^= user_seed;
1762 for attr in tcx.get_attrs(did).iter() {
1763 for r in attr::find_repr_attrs(&tcx.sess, attr) {
1764 flags.insert(match r {
1765 attr::ReprC => ReprFlags::IS_C,
1766 attr::ReprPacked(pack) => {
1767 let pack = Align::from_bytes(pack as u64).unwrap();
1768 min_pack = Some(if let Some(min_pack) = min_pack {
1775 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1776 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
1777 attr::ReprSimd => ReprFlags::IS_SIMD,
1778 attr::ReprInt(i) => {
1782 attr::ReprAlign(align) => {
1783 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
1790 // If `-Z randomize-layout` was enabled for the type definition then we can
1791 // consider performing layout randomization
1792 if tcx.sess.opts.debugging_opts.randomize_layout {
1793 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1796 // This is here instead of layout because the choice must make it into metadata.
1797 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
1798 flags.insert(ReprFlags::IS_LINEAR);
1801 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1805 pub fn simd(&self) -> bool {
1806 self.flags.contains(ReprFlags::IS_SIMD)
1810 pub fn c(&self) -> bool {
1811 self.flags.contains(ReprFlags::IS_C)
1815 pub fn packed(&self) -> bool {
1820 pub fn transparent(&self) -> bool {
1821 self.flags.contains(ReprFlags::IS_TRANSPARENT)
1825 pub fn linear(&self) -> bool {
1826 self.flags.contains(ReprFlags::IS_LINEAR)
1830 pub fn hide_niche(&self) -> bool {
1831 self.flags.contains(ReprFlags::HIDE_NICHE)
1834 /// Returns the discriminant type, given these `repr` options.
1835 /// This must only be called on enums!
1836 pub fn discr_type(&self) -> attr::IntType {
1837 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1840 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
1841 /// layout" optimizations, such as representing `Foo<&T>` as a
1843 pub fn inhibit_enum_layout_opt(&self) -> bool {
1844 self.c() || self.int.is_some()
1847 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
1848 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
1849 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
1850 if let Some(pack) = self.pack {
1851 if pack.bytes() == 1 {
1856 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
1859 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
1860 /// was enabled for its declaration crate
1861 pub fn can_randomize_type_layout(&self) -> bool {
1862 !self.inhibit_struct_field_reordering_opt()
1863 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
1866 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
1867 pub fn inhibit_union_abi_opt(&self) -> bool {
1872 impl<'tcx> FieldDef {
1873 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
1874 /// typically obtained via the second field of [`TyKind::Adt`].
1875 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
1876 tcx.type_of(self.did).subst(tcx, subst)
1879 /// Computes the `Ident` of this variant by looking up the `Span`
1880 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1881 Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
1885 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
1887 #[derive(Debug, PartialEq, Eq)]
1888 pub enum ImplOverlapKind {
1889 /// These impls are always allowed to overlap.
1891 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1894 /// These impls are allowed to overlap, but that raises
1895 /// an issue #33140 future-compatibility warning.
1897 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
1898 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
1900 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
1901 /// that difference, making what reduces to the following set of impls:
1905 /// impl Trait for dyn Send + Sync {}
1906 /// impl Trait for dyn Sync + Send {}
1909 /// Obviously, once we made these types be identical, that code causes a coherence
1910 /// error and a fairly big headache for us. However, luckily for us, the trait
1911 /// `Trait` used in this case is basically a marker trait, and therefore having
1912 /// overlapping impls for it is sound.
1914 /// To handle this, we basically regard the trait as a marker trait, with an additional
1915 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
1916 /// it has the following restrictions:
1918 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
1920 /// 2. The trait-ref of both impls must be equal.
1921 /// 3. The trait-ref of both impls must be a trait object type consisting only of
1923 /// 4. Neither of the impls can have any where-clauses.
1925 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
1929 impl<'tcx> TyCtxt<'tcx> {
1930 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1931 self.typeck(self.hir().body_owner_def_id(body))
1934 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1935 self.associated_items(id)
1936 .in_definition_order()
1937 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
1940 fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
1941 self.hir().get_if_local(def_id).and_then(|node| node.ident())
1944 fn item_name_from_def_id(self, def_id: DefId) -> Option<Symbol> {
1945 if def_id.index == CRATE_DEF_INDEX {
1946 Some(self.crate_name(def_id.krate))
1948 let def_key = self.def_key(def_id);
1949 match def_key.disambiguated_data.data {
1950 // The name of a constructor is that of its parent.
1951 rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId {
1952 krate: def_id.krate,
1953 index: def_key.parent.unwrap(),
1955 _ => def_key.disambiguated_data.data.get_opt_name(),
1960 /// Look up the name of an item across crates. This does not look at HIR.
1962 /// When possible, this function should be used for cross-crate lookups over
1963 /// [`opt_item_name`] to avoid invalidating the incremental cache. If you
1964 /// need to handle items without a name, or HIR items that will not be
1965 /// serialized cross-crate, or if you need the span of the item, use
1966 /// [`opt_item_name`] instead.
1968 /// [`opt_item_name`]: Self::opt_item_name
1969 pub fn item_name(self, id: DefId) -> Symbol {
1970 // Look at cross-crate items first to avoid invalidating the incremental cache
1971 // unless we have to.
1972 self.item_name_from_def_id(id).unwrap_or_else(|| {
1973 bug!("item_name: no name for {:?}", self.def_path(id));
1977 /// Look up the name and span of an item or [`Node`].
1979 /// See [`item_name`][Self::item_name] for more information.
1980 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
1981 // Look at the HIR first so the span will be correct if this is a local item.
1982 self.item_name_from_hir(def_id)
1983 .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span))
1986 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
1987 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
1988 Some(self.associated_item(def_id))
1994 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
1995 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
1998 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2002 .position(|field| self.hygienic_eq(ident, field.ident(self), variant.def_id))
2005 /// Returns `true` if the impls are the same polarity and the trait either
2006 /// has no items or is annotated `#[marker]` and prevents item overrides.
2007 pub fn impls_are_allowed_to_overlap(
2011 ) -> Option<ImplOverlapKind> {
2012 // If either trait impl references an error, they're allowed to overlap,
2013 // as one of them essentially doesn't exist.
2014 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2015 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2017 return Some(ImplOverlapKind::Permitted { marker: false });
2020 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2021 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2022 // `#[rustc_reservation_impl]` impls don't overlap with anything
2024 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2027 return Some(ImplOverlapKind::Permitted { marker: false });
2029 (ImplPolarity::Positive, ImplPolarity::Negative)
2030 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2031 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2033 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2038 (ImplPolarity::Positive, ImplPolarity::Positive)
2039 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2042 let is_marker_overlap = {
2043 let is_marker_impl = |def_id: DefId| -> bool {
2044 let trait_ref = self.impl_trait_ref(def_id);
2045 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2047 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2050 if is_marker_overlap {
2052 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2055 Some(ImplOverlapKind::Permitted { marker: true })
2057 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2058 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2059 if self_ty1 == self_ty2 {
2061 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2064 return Some(ImplOverlapKind::Issue33140);
2067 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2068 def_id1, def_id2, self_ty1, self_ty2
2074 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2079 /// Returns `ty::VariantDef` if `res` refers to a struct,
2080 /// or variant or their constructors, panics otherwise.
2081 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2083 Res::Def(DefKind::Variant, did) => {
2084 let enum_did = self.parent(did).unwrap();
2085 self.adt_def(enum_did).variant_with_id(did)
2087 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2088 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2089 let variant_did = self.parent(variant_ctor_did).unwrap();
2090 let enum_did = self.parent(variant_did).unwrap();
2091 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2093 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2094 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2095 self.adt_def(struct_did).non_enum_variant()
2097 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2101 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2102 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2104 ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
2107 | DefKind::AssocConst
2109 | DefKind::AnonConst
2110 | DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
2111 // If the caller wants `mir_for_ctfe` of a function they should not be using
2112 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2114 assert_eq!(def.const_param_did, None);
2115 self.optimized_mir(def.did)
2118 ty::InstanceDef::VtableShim(..)
2119 | ty::InstanceDef::ReifyShim(..)
2120 | ty::InstanceDef::Intrinsic(..)
2121 | ty::InstanceDef::FnPtrShim(..)
2122 | ty::InstanceDef::Virtual(..)
2123 | ty::InstanceDef::ClosureOnceShim { .. }
2124 | ty::InstanceDef::DropGlue(..)
2125 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2129 /// Gets the attributes of a definition.
2130 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
2131 if let Some(did) = did.as_local() {
2132 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2134 self.item_attrs(did)
2138 /// Determines whether an item is annotated with an attribute.
2139 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2140 self.sess.contains_name(&self.get_attrs(did), attr)
2143 /// Returns `true` if this is an `auto trait`.
2144 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2145 self.trait_def(trait_def_id).has_auto_impl
2148 /// Returns layout of a generator. Layout might be unavailable if the
2149 /// generator is tainted by errors.
2150 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2151 self.optimized_mir(def_id).generator_layout()
2154 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2155 /// If it implements no trait, returns `None`.
2156 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2157 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2160 /// If the given defid describes a method belonging to an impl, returns the
2161 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2162 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2163 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
2164 TraitContainer(_) => None,
2165 ImplContainer(def_id) => Some(def_id),
2169 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2170 /// with the name of the crate containing the impl.
2171 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2172 if let Some(impl_did) = impl_did.as_local() {
2173 Ok(self.def_span(impl_did))
2175 Err(self.crate_name(impl_did.krate))
2179 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2180 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2181 /// definition's parent/scope to perform comparison.
2182 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2183 // We could use `Ident::eq` here, but we deliberately don't. The name
2184 // comparison fails frequently, and we want to avoid the expensive
2185 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2186 use_name.name == def_name.name
2190 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2193 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2194 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2198 pub fn adjust_ident_and_get_scope(
2203 ) -> (Ident, DefId) {
2206 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2207 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2208 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2212 pub fn is_object_safe(self, key: DefId) -> bool {
2213 self.object_safety_violations(key).is_empty()
2217 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
2218 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
2219 let def_id = def_id.as_local()?;
2220 if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) {
2221 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2222 return match opaque_ty.origin {
2223 hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
2226 hir::OpaqueTyOrigin::TyAlias => None,
2233 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2235 ast::IntTy::Isize => IntTy::Isize,
2236 ast::IntTy::I8 => IntTy::I8,
2237 ast::IntTy::I16 => IntTy::I16,
2238 ast::IntTy::I32 => IntTy::I32,
2239 ast::IntTy::I64 => IntTy::I64,
2240 ast::IntTy::I128 => IntTy::I128,
2244 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2246 ast::UintTy::Usize => UintTy::Usize,
2247 ast::UintTy::U8 => UintTy::U8,
2248 ast::UintTy::U16 => UintTy::U16,
2249 ast::UintTy::U32 => UintTy::U32,
2250 ast::UintTy::U64 => UintTy::U64,
2251 ast::UintTy::U128 => UintTy::U128,
2255 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2257 ast::FloatTy::F32 => FloatTy::F32,
2258 ast::FloatTy::F64 => FloatTy::F64,
2262 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2264 IntTy::Isize => ast::IntTy::Isize,
2265 IntTy::I8 => ast::IntTy::I8,
2266 IntTy::I16 => ast::IntTy::I16,
2267 IntTy::I32 => ast::IntTy::I32,
2268 IntTy::I64 => ast::IntTy::I64,
2269 IntTy::I128 => ast::IntTy::I128,
2273 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2275 UintTy::Usize => ast::UintTy::Usize,
2276 UintTy::U8 => ast::UintTy::U8,
2277 UintTy::U16 => ast::UintTy::U16,
2278 UintTy::U32 => ast::UintTy::U32,
2279 UintTy::U64 => ast::UintTy::U64,
2280 UintTy::U128 => ast::UintTy::U128,
2284 pub fn provide(providers: &mut ty::query::Providers) {
2285 closure::provide(providers);
2286 context::provide(providers);
2287 erase_regions::provide(providers);
2288 layout::provide(providers);
2289 util::provide(providers);
2290 print::provide(providers);
2291 super::util::bug::provide(providers);
2292 super::middle::provide(providers);
2293 *providers = ty::query::Providers {
2294 trait_impls_of: trait_def::trait_impls_of_provider,
2295 type_uninhabited_from: inhabitedness::type_uninhabited_from,
2296 const_param_default: consts::const_param_default,
2297 vtable_allocation: vtable::vtable_allocation_provider,
2302 /// A map for the local crate mapping each type to a vector of its
2303 /// inherent impls. This is not meant to be used outside of coherence;
2304 /// rather, you should request the vector for a specific type via
2305 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2306 /// (constructing this map requires touching the entire crate).
2307 #[derive(Clone, Debug, Default, HashStable)]
2308 pub struct CrateInherentImpls {
2309 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2312 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2313 pub struct SymbolName<'tcx> {
2314 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2315 pub name: &'tcx str,
2318 impl<'tcx> SymbolName<'tcx> {
2319 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2321 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2326 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2327 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2328 fmt::Display::fmt(&self.name, fmt)
2332 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2333 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2334 fmt::Display::fmt(&self.name, fmt)
2338 #[derive(Debug, Default, Copy, Clone)]
2339 pub struct FoundRelationships {
2340 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2341 /// obligation, where:
2343 /// * `Foo` is not `Sized`
2344 /// * `(): Foo` may be satisfied
2345 pub self_in_trait: bool,
2346 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2347 /// _>::AssocType = ?T`