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;
48 use std::ops::ControlFlow;
51 pub use crate::ty::diagnostics::*;
52 pub use rustc_type_ir::InferTy::*;
53 pub use rustc_type_ir::*;
55 pub use self::binding::BindingMode;
56 pub use self::binding::BindingMode::*;
57 pub use self::closure::{
58 is_ancestor_or_same_capture, place_to_string_for_capture, BorrowKind, CaptureInfo,
59 CapturedPlace, ClosureKind, MinCaptureInformationMap, MinCaptureList,
60 RootVariableMinCaptureList, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath,
63 pub use self::consts::{
64 Const, ConstInt, ConstKind, ConstS, InferConst, ScalarInt, Unevaluated, ValTree,
66 pub use self::context::{
67 tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
68 CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorInteriorTypeCause, GlobalCtxt,
69 Lift, OnDiskCache, TyCtxt, TypeckResults, UserType, UserTypeAnnotationIndex,
71 pub use self::instance::{Instance, InstanceDef};
72 pub use self::list::List;
73 pub use self::sty::BoundRegionKind::*;
74 pub use self::sty::RegionKind::*;
75 pub use self::sty::TyKind::*;
77 Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind,
78 CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBoundRegion,
79 ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig,
80 GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts, InlineConstSubstsParts, ParamConst,
81 ParamTy, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig,
82 PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut,
83 UpvarSubsts, VarianceDiagInfo,
85 pub use self::trait_def::TraitDef;
96 pub mod inhabitedness;
98 pub mod normalize_erasing_regions;
119 mod structural_impls;
124 pub type RegisteredTools = FxHashSet<Ident>;
127 pub struct ResolverOutputs {
128 pub definitions: rustc_hir::definitions::Definitions,
129 pub cstore: Box<CrateStoreDyn>,
130 pub visibilities: FxHashMap<LocalDefId, Visibility>,
131 pub access_levels: AccessLevels,
132 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
133 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
134 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
135 pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
136 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
137 /// Extern prelude entries. The value is `true` if the entry was introduced
138 /// via `extern crate` item and not `--extern` option or compiler built-in.
139 pub extern_prelude: FxHashMap<Symbol, bool>,
140 pub main_def: Option<MainDefinition>,
141 pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
142 /// A list of proc macro LocalDefIds, written out in the order in which
143 /// they are declared in the static array generated by proc_macro_harness.
144 pub proc_macros: Vec<LocalDefId>,
145 /// Mapping from ident span to path span for paths that don't exist as written, but that
146 /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
147 pub confused_type_with_std_module: FxHashMap<Span, Span>,
148 pub registered_tools: RegisteredTools,
151 #[derive(Clone, Copy, Debug)]
152 pub struct MainDefinition {
153 pub res: Res<ast::NodeId>,
158 impl MainDefinition {
159 pub fn opt_fn_def_id(self) -> Option<DefId> {
160 if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
164 /// The "header" of an impl is everything outside the body: a Self type, a trait
165 /// ref (in the case of a trait impl), and a set of predicates (from the
166 /// bounds / where-clauses).
167 #[derive(Clone, Debug, TypeFoldable)]
168 pub struct ImplHeader<'tcx> {
169 pub impl_def_id: DefId,
170 pub self_ty: Ty<'tcx>,
171 pub trait_ref: Option<TraitRef<'tcx>>,
172 pub predicates: Vec<Predicate<'tcx>>,
187 pub enum ImplPolarity {
188 /// `impl Trait for Type`
190 /// `impl !Trait for Type`
192 /// `#[rustc_reservation_impl] impl Trait for Type`
194 /// This is a "stability hack", not a real Rust feature.
195 /// See #64631 for details.
200 /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
201 pub fn flip(&self) -> Option<ImplPolarity> {
203 ImplPolarity::Positive => Some(ImplPolarity::Negative),
204 ImplPolarity::Negative => Some(ImplPolarity::Positive),
205 ImplPolarity::Reservation => None,
210 impl fmt::Display for ImplPolarity {
211 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
213 Self::Positive => f.write_str("positive"),
214 Self::Negative => f.write_str("negative"),
215 Self::Reservation => f.write_str("reservation"),
220 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
221 pub enum Visibility {
222 /// Visible everywhere (including in other crates).
224 /// Visible only in the given crate-local module.
226 /// Not visible anywhere in the local crate. This is the visibility of private external items.
230 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
231 pub enum BoundConstness {
234 /// `T: ~const Trait`
236 /// Requires resolving to const only when we are in a const context.
240 impl BoundConstness {
241 /// Reduce `self` and `constness` to two possible combined states instead of four.
242 pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
243 match (constness, self) {
244 (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
246 *this = BoundConstness::NotConst;
247 hir::Constness::NotConst
253 impl fmt::Display for BoundConstness {
254 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
256 Self::NotConst => f.write_str("normal"),
257 Self::ConstIfConst => f.write_str("`~const`"),
274 pub struct ClosureSizeProfileData<'tcx> {
275 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
276 pub before_feature_tys: Ty<'tcx>,
277 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
278 pub after_feature_tys: Ty<'tcx>,
281 pub trait DefIdTree: Copy {
282 fn parent(self, id: DefId) -> Option<DefId>;
284 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
285 if descendant.krate != ancestor.krate {
289 while descendant != ancestor {
290 match self.parent(descendant) {
291 Some(parent) => descendant = parent,
292 None => return false,
299 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
300 fn parent(self, id: DefId) -> Option<DefId> {
301 self.def_key(id).parent.map(|index| DefId { index, ..id })
306 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
307 match visibility.node {
308 hir::VisibilityKind::Public => Visibility::Public,
309 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
310 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
311 // If there is no resolution, `resolve` will have already reported an error, so
312 // assume that the visibility is public to avoid reporting more privacy errors.
313 Res::Err => Visibility::Public,
314 def => Visibility::Restricted(def.def_id()),
316 hir::VisibilityKind::Inherited => {
317 Visibility::Restricted(tcx.parent_module(id).to_def_id())
322 /// Returns `true` if an item with this visibility is accessible from the given block.
323 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
324 let restriction = match self {
325 // Public items are visible everywhere.
326 Visibility::Public => return true,
327 // Private items from other crates are visible nowhere.
328 Visibility::Invisible => return false,
329 // Restricted items are visible in an arbitrary local module.
330 Visibility::Restricted(other) if other.krate != module.krate => return false,
331 Visibility::Restricted(module) => module,
334 tree.is_descendant_of(module, restriction)
337 /// Returns `true` if this visibility is at least as accessible as the given visibility
338 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
339 let vis_restriction = match vis {
340 Visibility::Public => return self == Visibility::Public,
341 Visibility::Invisible => return true,
342 Visibility::Restricted(module) => module,
345 self.is_accessible_from(vis_restriction, tree)
348 // Returns `true` if this item is visible anywhere in the local crate.
349 pub fn is_visible_locally(self) -> bool {
351 Visibility::Public => true,
352 Visibility::Restricted(def_id) => def_id.is_local(),
353 Visibility::Invisible => false,
357 pub fn is_public(self) -> bool {
358 matches!(self, Visibility::Public)
362 /// The crate variances map is computed during typeck and contains the
363 /// variance of every item in the local crate. You should not use it
364 /// directly, because to do so will make your pass dependent on the
365 /// HIR of every item in the local crate. Instead, use
366 /// `tcx.variances_of()` to get the variance for a *particular*
368 #[derive(HashStable, Debug)]
369 pub struct CrateVariancesMap<'tcx> {
370 /// For each item with generics, maps to a vector of the variance
371 /// of its generics. If an item has no generics, it will have no
373 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
376 // Contains information needed to resolve types and (in the future) look up
377 // the types of AST nodes.
378 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
379 pub struct CReaderCacheKey {
380 pub cnum: Option<CrateNum>,
384 /// Represents a type.
387 /// - This is a very "dumb" struct (with no derives and no `impls`).
388 /// - Values of this type are always interned and thus unique, and are stored
389 /// as an `Interned<TyS>`.
390 /// - `Ty` (which contains a reference to a `Interned<TyS>`) or `Interned<TyS>`
391 /// should be used everywhere instead of `TyS`. In particular, `Ty` has most
392 /// of the relevant methods.
393 #[derive(PartialEq, Eq, PartialOrd, Ord)]
394 #[allow(rustc::usage_of_ty_tykind)]
395 crate struct TyS<'tcx> {
396 /// This field shouldn't be used directly and may be removed in the future.
397 /// Use `Ty::kind()` instead.
400 /// This field provides fast access to information that is also contained
403 /// This field shouldn't be used directly and may be removed in the future.
404 /// Use `Ty::flags()` instead.
407 /// This field provides fast access to information that is also contained
410 /// This is a kind of confusing thing: it stores the smallest
413 /// (a) the binder itself captures nothing but
414 /// (b) all the late-bound things within the type are captured
415 /// by some sub-binder.
417 /// So, for a type without any late-bound things, like `u32`, this
418 /// will be *innermost*, because that is the innermost binder that
419 /// captures nothing. But for a type `&'D u32`, where `'D` is a
420 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
421 /// -- the binder itself does not capture `D`, but `D` is captured
422 /// by an inner binder.
424 /// We call this concept an "exclusive" binder `D` because all
425 /// De Bruijn indices within the type are contained within `0..D`
427 outer_exclusive_binder: ty::DebruijnIndex,
429 /// The stable hash of the type. This way hashing of types will not have to work
430 /// on the address of the type anymore, but can instead just read this field
431 stable_hash: Fingerprint,
434 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
435 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
436 static_assert_size!(TyS<'_>, 56);
438 /// Use this rather than `TyS`, whenever possible.
439 #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
440 #[rustc_diagnostic_item = "Ty"]
441 #[rustc_pass_by_value]
442 pub struct Ty<'tcx>(Interned<'tcx, TyS<'tcx>>);
444 // Statics only used for internal testing.
445 pub static BOOL_TY: Ty<'static> = Ty(Interned::new_unchecked(&BOOL_TYS));
446 static BOOL_TYS: TyS<'static> = TyS {
448 flags: TypeFlags::empty(),
449 outer_exclusive_binder: DebruijnIndex::from_usize(0),
450 stable_hash: Fingerprint::ZERO,
453 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Ty<'tcx> {
454 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
458 // The other fields just provide fast access to information that is
459 // also contained in `kind`, so no need to hash them.
462 outer_exclusive_binder: _,
467 if *stable_hash == Fingerprint::ZERO {
468 // No cached hash available. This can only mean that incremental is disabled.
469 // We don't cache stable hashes in non-incremental mode, because they are used
470 // so rarely that the performance actually suffers.
472 let stable_hash: Fingerprint = {
473 let mut hasher = StableHasher::new();
474 hcx.while_hashing_spans(false, |hcx| {
475 hcx.with_node_id_hashing_mode(NodeIdHashingMode::HashDefPath, |hcx| {
476 kind.hash_stable(hcx, &mut hasher)
481 stable_hash.hash_stable(hcx, hasher);
483 stable_hash.hash_stable(hcx, hasher);
488 impl ty::EarlyBoundRegion {
489 /// Does this early bound region have a name? Early bound regions normally
490 /// always have names except when using anonymous lifetimes (`'_`).
491 pub fn has_name(&self) -> bool {
492 self.name != kw::UnderscoreLifetime
496 /// Represents a predicate.
498 /// See comments on `TyS`, which apply here too (albeit for
499 /// `PredicateS`/`Predicate` rather than `TyS`/`Ty`).
501 crate struct PredicateS<'tcx> {
502 kind: Binder<'tcx, PredicateKind<'tcx>>,
504 /// See the comment for the corresponding field of [TyS].
505 outer_exclusive_binder: ty::DebruijnIndex,
508 // This type is used a lot. Make sure it doesn't unintentionally get bigger.
509 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
510 static_assert_size!(PredicateS<'_>, 56);
512 /// Use this rather than `PredicateS`, whenever possible.
513 #[derive(Clone, Copy, PartialEq, Eq, Hash)]
514 #[rustc_pass_by_value]
515 pub struct Predicate<'tcx>(Interned<'tcx, PredicateS<'tcx>>);
517 impl<'tcx> Predicate<'tcx> {
518 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
520 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
525 pub fn flags(self) -> TypeFlags {
530 pub fn outer_exclusive_binder(self) -> DebruijnIndex {
531 self.0.outer_exclusive_binder
534 /// Flips the polarity of a Predicate.
536 /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
537 pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
540 .map_bound(|kind| match kind {
541 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
542 Some(PredicateKind::Trait(TraitPredicate {
545 polarity: polarity.flip()?,
553 Some(tcx.mk_predicate(kind))
557 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
558 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
562 // The other fields just provide fast access to information that is
563 // also contained in `kind`, so no need to hash them.
565 outer_exclusive_binder: _,
568 kind.hash_stable(hcx, hasher);
572 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
573 #[derive(HashStable, TypeFoldable)]
574 pub enum PredicateKind<'tcx> {
575 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
576 /// the `Self` type of the trait reference and `A`, `B`, and `C`
577 /// would be the type parameters.
578 Trait(TraitPredicate<'tcx>),
581 RegionOutlives(RegionOutlivesPredicate<'tcx>),
584 TypeOutlives(TypeOutlivesPredicate<'tcx>),
586 /// `where <T as TraitRef>::Name == X`, approximately.
587 /// See the `ProjectionPredicate` struct for details.
588 Projection(ProjectionPredicate<'tcx>),
590 /// No syntax: `T` well-formed.
591 WellFormed(GenericArg<'tcx>),
593 /// Trait must be object-safe.
596 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
597 /// for some substitutions `...` and `T` being a closure type.
598 /// Satisfied (or refuted) once we know the closure's kind.
599 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
603 /// This obligation is created most often when we have two
604 /// unresolved type variables and hence don't have enough
605 /// information to process the subtyping obligation yet.
606 Subtype(SubtypePredicate<'tcx>),
608 /// `T1` coerced to `T2`
610 /// Like a subtyping obligation, this is created most often
611 /// when we have two unresolved type variables and hence
612 /// don't have enough information to process the coercion
613 /// obligation yet. At the moment, we actually process coercions
614 /// very much like subtyping and don't handle the full coercion
616 Coerce(CoercePredicate<'tcx>),
618 /// Constant initializer must evaluate successfully.
619 ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
621 /// Constants must be equal. The first component is the const that is expected.
622 ConstEquate(Const<'tcx>, Const<'tcx>),
624 /// Represents a type found in the environment that we can use for implied bounds.
626 /// Only used for Chalk.
627 TypeWellFormedFromEnv(Ty<'tcx>),
630 /// The crate outlives map is computed during typeck and contains the
631 /// outlives of every item in the local crate. You should not use it
632 /// directly, because to do so will make your pass dependent on the
633 /// HIR of every item in the local crate. Instead, use
634 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
636 #[derive(HashStable, Debug)]
637 pub struct CratePredicatesMap<'tcx> {
638 /// For each struct with outlive bounds, maps to a vector of the
639 /// predicate of its outlive bounds. If an item has no outlives
640 /// bounds, it will have no entry.
641 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
644 impl<'tcx> Predicate<'tcx> {
645 /// Performs a substitution suitable for going from a
646 /// poly-trait-ref to supertraits that must hold if that
647 /// poly-trait-ref holds. This is slightly different from a normal
648 /// substitution in terms of what happens with bound regions. See
649 /// lengthy comment below for details.
650 pub fn subst_supertrait(
653 trait_ref: &ty::PolyTraitRef<'tcx>,
654 ) -> Predicate<'tcx> {
655 // The interaction between HRTB and supertraits is not entirely
656 // obvious. Let me walk you (and myself) through an example.
658 // Let's start with an easy case. Consider two traits:
660 // trait Foo<'a>: Bar<'a,'a> { }
661 // trait Bar<'b,'c> { }
663 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
664 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
665 // knew that `Foo<'x>` (for any 'x) then we also know that
666 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
667 // normal substitution.
669 // In terms of why this is sound, the idea is that whenever there
670 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
671 // holds. So if there is an impl of `T:Foo<'a>` that applies to
672 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
675 // Another example to be careful of is this:
677 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
678 // trait Bar1<'b,'c> { }
680 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
681 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
682 // reason is similar to the previous example: any impl of
683 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
684 // basically we would want to collapse the bound lifetimes from
685 // the input (`trait_ref`) and the supertraits.
687 // To achieve this in practice is fairly straightforward. Let's
688 // consider the more complicated scenario:
690 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
691 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
692 // where both `'x` and `'b` would have a DB index of 1.
693 // The substitution from the input trait-ref is therefore going to be
694 // `'a => 'x` (where `'x` has a DB index of 1).
695 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
696 // early-bound parameter and `'b' is a late-bound parameter with a
698 // - If we replace `'a` with `'x` from the input, it too will have
699 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
700 // just as we wanted.
702 // There is only one catch. If we just apply the substitution `'a
703 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
704 // adjust the DB index because we substituting into a binder (it
705 // tries to be so smart...) resulting in `for<'x> for<'b>
706 // Bar1<'x,'b>` (we have no syntax for this, so use your
707 // imagination). Basically the 'x will have DB index of 2 and 'b
708 // will have DB index of 1. Not quite what we want. So we apply
709 // the substitution to the *contents* of the trait reference,
710 // rather than the trait reference itself (put another way, the
711 // substitution code expects equal binding levels in the values
712 // from the substitution and the value being substituted into, and
713 // this trick achieves that).
715 // Working through the second example:
716 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
717 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
718 // We want to end up with:
719 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
721 // 1) We must shift all bound vars in predicate by the length
722 // of trait ref's bound vars. So, we would end up with predicate like
723 // Self: Bar1<'a, '^0.1>
724 // 2) We can then apply the trait substs to this, ending up with
725 // T: Bar1<'^0.0, '^0.1>
726 // 3) Finally, to create the final bound vars, we concatenate the bound
727 // vars of the trait ref with those of the predicate:
729 let bound_pred = self.kind();
730 let pred_bound_vars = bound_pred.bound_vars();
731 let trait_bound_vars = trait_ref.bound_vars();
732 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
734 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
735 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
736 let new = shifted_pred.subst(tcx, trait_ref.skip_binder().substs);
737 // 3) ['x] + ['b] -> ['x, 'b]
739 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
740 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
744 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
745 #[derive(HashStable, TypeFoldable)]
746 pub struct TraitPredicate<'tcx> {
747 pub trait_ref: TraitRef<'tcx>,
749 pub constness: BoundConstness,
751 /// If polarity is Positive: we are proving that the trait is implemented.
753 /// If polarity is Negative: we are proving that a negative impl of this trait
754 /// exists. (Note that coherence also checks whether negative impls of supertraits
755 /// exist via a series of predicates.)
757 /// If polarity is Reserved: that's a bug.
758 pub polarity: ImplPolarity,
761 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
763 impl<'tcx> TraitPredicate<'tcx> {
764 pub fn remap_constness(&mut self, tcx: TyCtxt<'tcx>, param_env: &mut ParamEnv<'tcx>) {
765 if unlikely!(Some(self.trait_ref.def_id) == tcx.lang_items().drop_trait()) {
766 // remap without changing constness of this predicate.
767 // this is because `T: ~const Drop` has a different meaning to `T: Drop`
768 param_env.remap_constness_with(self.constness)
770 *param_env = param_env.with_constness(self.constness.and(param_env.constness()))
774 /// Remap the constness of this predicate before emitting it for diagnostics.
775 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
776 // this is different to `remap_constness` that callees want to print this predicate
777 // in case of selection errors. `T: ~const Drop` bounds cannot end up here when the
778 // param_env is not const because we it is always satisfied in non-const contexts.
779 if let hir::Constness::NotConst = param_env.constness() {
780 self.constness = ty::BoundConstness::NotConst;
784 pub fn def_id(self) -> DefId {
785 self.trait_ref.def_id
788 pub fn self_ty(self) -> Ty<'tcx> {
789 self.trait_ref.self_ty()
793 pub fn is_const_if_const(self) -> bool {
794 self.constness == BoundConstness::ConstIfConst
798 impl<'tcx> PolyTraitPredicate<'tcx> {
799 pub fn def_id(self) -> DefId {
800 // Ok to skip binder since trait `DefId` does not care about regions.
801 self.skip_binder().def_id()
804 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
805 self.map_bound(|trait_ref| trait_ref.self_ty())
808 /// Remap the constness of this predicate before emitting it for diagnostics.
809 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
810 *self = self.map_bound(|mut p| {
811 p.remap_constness_diag(param_env);
817 pub fn is_const_if_const(self) -> bool {
818 self.skip_binder().is_const_if_const()
822 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
823 #[derive(HashStable, TypeFoldable)]
824 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
825 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
826 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
827 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
828 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
830 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
831 /// whether the `a` type is the type that we should label as "expected" when
832 /// presenting user diagnostics.
833 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
834 #[derive(HashStable, TypeFoldable)]
835 pub struct SubtypePredicate<'tcx> {
836 pub a_is_expected: bool,
840 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
842 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
843 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
844 #[derive(HashStable, TypeFoldable)]
845 pub struct CoercePredicate<'tcx> {
849 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
851 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)]
852 #[derive(HashStable, TypeFoldable)]
853 pub enum Term<'tcx> {
858 impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
859 fn from(ty: Ty<'tcx>) -> Self {
864 impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
865 fn from(c: Const<'tcx>) -> Self {
870 impl<'tcx> Term<'tcx> {
871 pub fn ty(&self) -> Option<Ty<'tcx>> {
872 if let Term::Ty(ty) = self { Some(*ty) } else { None }
874 pub fn ct(&self) -> Option<Const<'tcx>> {
875 if let Term::Const(c) = self { Some(*c) } else { None }
879 /// This kind of predicate has no *direct* correspondent in the
880 /// syntax, but it roughly corresponds to the syntactic forms:
882 /// 1. `T: TraitRef<..., Item = Type>`
883 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
885 /// In particular, form #1 is "desugared" to the combination of a
886 /// normal trait predicate (`T: TraitRef<...>`) and one of these
887 /// predicates. Form #2 is a broader form in that it also permits
888 /// equality between arbitrary types. Processing an instance of
889 /// Form #2 eventually yields one of these `ProjectionPredicate`
890 /// instances to normalize the LHS.
891 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
892 #[derive(HashStable, TypeFoldable)]
893 pub struct ProjectionPredicate<'tcx> {
894 pub projection_ty: ProjectionTy<'tcx>,
895 pub term: Term<'tcx>,
898 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
900 impl<'tcx> PolyProjectionPredicate<'tcx> {
901 /// Returns the `DefId` of the trait of the associated item being projected.
903 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
904 self.skip_binder().projection_ty.trait_def_id(tcx)
907 /// Get the [PolyTraitRef] required for this projection to be well formed.
908 /// Note that for generic associated types the predicates of the associated
909 /// type also need to be checked.
911 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
912 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
913 // `self.0.trait_ref` is permitted to have escaping regions.
914 // This is because here `self` has a `Binder` and so does our
915 // return value, so we are preserving the number of binding
917 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
920 pub fn term(&self) -> Binder<'tcx, Term<'tcx>> {
921 self.map_bound(|predicate| predicate.term)
924 /// The `DefId` of the `TraitItem` for the associated type.
926 /// Note that this is not the `DefId` of the `TraitRef` containing this
927 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
928 pub fn projection_def_id(&self) -> DefId {
929 // Ok to skip binder since trait `DefId` does not care about regions.
930 self.skip_binder().projection_ty.item_def_id
934 pub trait ToPolyTraitRef<'tcx> {
935 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
938 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
939 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
940 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
944 pub trait ToPredicate<'tcx> {
945 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
948 impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
950 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
951 tcx.mk_predicate(self)
955 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
956 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
957 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
961 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
962 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
963 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
967 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
968 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
969 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
973 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
974 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
975 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
979 impl<'tcx> Predicate<'tcx> {
980 pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
981 let predicate = self.kind();
982 match predicate.skip_binder() {
983 PredicateKind::Trait(t) => Some(predicate.rebind(t)),
984 PredicateKind::Projection(..)
985 | PredicateKind::Subtype(..)
986 | PredicateKind::Coerce(..)
987 | PredicateKind::RegionOutlives(..)
988 | PredicateKind::WellFormed(..)
989 | PredicateKind::ObjectSafe(..)
990 | PredicateKind::ClosureKind(..)
991 | PredicateKind::TypeOutlives(..)
992 | PredicateKind::ConstEvaluatable(..)
993 | PredicateKind::ConstEquate(..)
994 | PredicateKind::TypeWellFormedFromEnv(..) => None,
998 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
999 let predicate = self.kind();
1000 match predicate.skip_binder() {
1001 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
1002 PredicateKind::Trait(..)
1003 | PredicateKind::Projection(..)
1004 | PredicateKind::Subtype(..)
1005 | PredicateKind::Coerce(..)
1006 | PredicateKind::RegionOutlives(..)
1007 | PredicateKind::WellFormed(..)
1008 | PredicateKind::ObjectSafe(..)
1009 | PredicateKind::ClosureKind(..)
1010 | PredicateKind::ConstEvaluatable(..)
1011 | PredicateKind::ConstEquate(..)
1012 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1017 /// Represents the bounds declared on a particular set of type
1018 /// parameters. Should eventually be generalized into a flag list of
1019 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
1020 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1021 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1022 /// the `GenericPredicates` are expressed in terms of the bound type
1023 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1024 /// represented a set of bounds for some particular instantiation,
1025 /// meaning that the generic parameters have been substituted with
1030 /// struct Foo<T, U: Bar<T>> { ... }
1032 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1033 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1034 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1035 /// [usize:Bar<isize>]]`.
1036 #[derive(Clone, Debug, TypeFoldable)]
1037 pub struct InstantiatedPredicates<'tcx> {
1038 pub predicates: Vec<Predicate<'tcx>>,
1039 pub spans: Vec<Span>,
1042 impl<'tcx> InstantiatedPredicates<'tcx> {
1043 pub fn empty() -> InstantiatedPredicates<'tcx> {
1044 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1047 pub fn is_empty(&self) -> bool {
1048 self.predicates.is_empty()
1052 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable, TypeFoldable)]
1053 pub struct OpaqueTypeKey<'tcx> {
1055 pub substs: SubstsRef<'tcx>,
1058 rustc_index::newtype_index! {
1059 /// "Universes" are used during type- and trait-checking in the
1060 /// presence of `for<..>` binders to control what sets of names are
1061 /// visible. Universes are arranged into a tree: the root universe
1062 /// contains names that are always visible. Each child then adds a new
1063 /// set of names that are visible, in addition to those of its parent.
1064 /// We say that the child universe "extends" the parent universe with
1067 /// To make this more concrete, consider this program:
1071 /// fn bar<T>(x: T) {
1072 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1076 /// The struct name `Foo` is in the root universe U0. But the type
1077 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1078 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1079 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1080 /// region `'a` is in a universe U2 that extends U1, because we can
1081 /// name it inside the fn type but not outside.
1083 /// Universes are used to do type- and trait-checking around these
1084 /// "forall" binders (also called **universal quantification**). The
1085 /// idea is that when, in the body of `bar`, we refer to `T` as a
1086 /// type, we aren't referring to any type in particular, but rather a
1087 /// kind of "fresh" type that is distinct from all other types we have
1088 /// actually declared. This is called a **placeholder** type, and we
1089 /// use universes to talk about this. In other words, a type name in
1090 /// universe 0 always corresponds to some "ground" type that the user
1091 /// declared, but a type name in a non-zero universe is a placeholder
1092 /// type -- an idealized representative of "types in general" that we
1093 /// use for checking generic functions.
1094 pub struct UniverseIndex {
1096 DEBUG_FORMAT = "U{}",
1100 impl UniverseIndex {
1101 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1103 /// Returns the "next" universe index in order -- this new index
1104 /// is considered to extend all previous universes. This
1105 /// corresponds to entering a `forall` quantifier. So, for
1106 /// example, suppose we have this type in universe `U`:
1109 /// for<'a> fn(&'a u32)
1112 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1113 /// new universe that extends `U` -- in this new universe, we can
1114 /// name the region `'a`, but that region was not nameable from
1115 /// `U` because it was not in scope there.
1116 pub fn next_universe(self) -> UniverseIndex {
1117 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1120 /// Returns `true` if `self` can name a name from `other` -- in other words,
1121 /// if the set of names in `self` is a superset of those in
1122 /// `other` (`self >= other`).
1123 pub fn can_name(self, other: UniverseIndex) -> bool {
1124 self.private >= other.private
1127 /// Returns `true` if `self` cannot name some names from `other` -- in other
1128 /// words, if the set of names in `self` is a strict subset of
1129 /// those in `other` (`self < other`).
1130 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1131 self.private < other.private
1135 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1136 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1137 /// regions/types/consts within the same universe simply have an unknown relationship to one
1139 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1140 pub struct Placeholder<T> {
1141 pub universe: UniverseIndex,
1145 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1147 T: HashStable<StableHashingContext<'a>>,
1149 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1150 self.universe.hash_stable(hcx, hasher);
1151 self.name.hash_stable(hcx, hasher);
1155 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1157 pub type PlaceholderType = Placeholder<BoundVar>;
1159 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1160 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1161 pub struct BoundConst<'tcx> {
1166 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1168 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1169 /// the `DefId` of the generic parameter it instantiates.
1171 /// This is used to avoid calls to `type_of` for const arguments during typeck
1172 /// which cause cycle errors.
1177 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1178 /// // ^ const parameter
1182 /// fn foo<const M: u8>(&self) -> usize { 42 }
1183 /// // ^ const parameter
1188 /// let _b = a.foo::<{ 3 + 7 }>();
1189 /// // ^^^^^^^^^ const argument
1193 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1194 /// which `foo` is used until we know the type of `a`.
1196 /// We only know the type of `a` once we are inside of `typeck(main)`.
1197 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1198 /// requires us to evaluate the const argument.
1200 /// To evaluate that const argument we need to know its type,
1201 /// which we would get using `type_of(const_arg)`. This requires us to
1202 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1203 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1204 /// which results in a cycle.
1206 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1208 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1209 /// already resolved `foo` so we know which const parameter this argument instantiates.
1210 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1211 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1212 /// trivial to compute.
1214 /// If we now want to use that constant in a place which potentionally needs its type
1215 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1216 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1217 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1218 /// to get the type of `did`.
1219 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1220 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1221 #[derive(Hash, HashStable)]
1222 pub struct WithOptConstParam<T> {
1224 /// The `DefId` of the corresponding generic parameter in case `did` is
1225 /// a const argument.
1227 /// Note that even if `did` is a const argument, this may still be `None`.
1228 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1229 /// to potentially update `param_did` in the case it is `None`.
1230 pub const_param_did: Option<DefId>,
1233 impl<T> WithOptConstParam<T> {
1234 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1236 pub fn unknown(did: T) -> WithOptConstParam<T> {
1237 WithOptConstParam { did, const_param_did: None }
1241 impl WithOptConstParam<LocalDefId> {
1242 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1243 /// `None` otherwise.
1245 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1246 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1249 /// In case `self` is unknown but `self.did` is a const argument, this returns
1250 /// a `WithOptConstParam` with the correct `const_param_did`.
1252 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1253 if self.const_param_did.is_none() {
1254 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1255 return Some(WithOptConstParam { did: self.did, const_param_did });
1262 pub fn to_global(self) -> WithOptConstParam<DefId> {
1263 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1266 pub fn def_id_for_type_of(self) -> DefId {
1267 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1271 impl WithOptConstParam<DefId> {
1272 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1275 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1278 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1279 if let Some(param_did) = self.const_param_did {
1280 if let Some(did) = self.did.as_local() {
1281 return Some((did, param_did));
1288 pub fn is_local(self) -> bool {
1292 pub fn def_id_for_type_of(self) -> DefId {
1293 self.const_param_did.unwrap_or(self.did)
1297 /// When type checking, we use the `ParamEnv` to track
1298 /// details about the set of where-clauses that are in scope at this
1299 /// particular point.
1300 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1301 pub struct ParamEnv<'tcx> {
1302 /// This packs both caller bounds and the reveal enum into one pointer.
1304 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1305 /// basically the set of bounds on the in-scope type parameters, translated
1306 /// into `Obligation`s, and elaborated and normalized.
1308 /// Use the `caller_bounds()` method to access.
1310 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1311 /// want `Reveal::All`.
1313 /// Note: This is packed, use the reveal() method to access it.
1314 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
1317 #[derive(Copy, Clone)]
1319 reveal: traits::Reveal,
1320 constness: hir::Constness,
1323 unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
1324 const BITS: usize = 2;
1326 fn into_usize(self) -> usize {
1328 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
1329 Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
1330 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
1331 Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
1335 unsafe fn from_usize(ptr: usize) -> Self {
1337 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1338 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
1339 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
1340 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
1341 _ => std::hint::unreachable_unchecked(),
1346 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1347 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1348 f.debug_struct("ParamEnv")
1349 .field("caller_bounds", &self.caller_bounds())
1350 .field("reveal", &self.reveal())
1351 .field("constness", &self.constness())
1356 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1357 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1358 self.caller_bounds().hash_stable(hcx, hasher);
1359 self.reveal().hash_stable(hcx, hasher);
1360 self.constness().hash_stable(hcx, hasher);
1364 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1365 fn try_super_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
1368 ) -> Result<Self, F::Error> {
1370 self.caller_bounds().try_fold_with(folder)?,
1371 self.reveal().try_fold_with(folder)?,
1372 self.constness().try_fold_with(folder)?,
1376 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1377 self.caller_bounds().visit_with(visitor)?;
1378 self.reveal().visit_with(visitor)?;
1379 self.constness().visit_with(visitor)
1383 impl<'tcx> ParamEnv<'tcx> {
1384 /// Construct a trait environment suitable for contexts where
1385 /// there are no where-clauses in scope. Hidden types (like `impl
1386 /// Trait`) are left hidden, so this is suitable for ordinary
1389 pub fn empty() -> Self {
1390 Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
1394 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1395 self.packed.pointer()
1399 pub fn reveal(self) -> traits::Reveal {
1400 self.packed.tag().reveal
1404 pub fn constness(self) -> hir::Constness {
1405 self.packed.tag().constness
1409 pub fn is_const(self) -> bool {
1410 self.packed.tag().constness == hir::Constness::Const
1413 /// Construct a trait environment with no where-clauses in scope
1414 /// where the values of all `impl Trait` and other hidden types
1415 /// are revealed. This is suitable for monomorphized, post-typeck
1416 /// environments like codegen or doing optimizations.
1418 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1419 /// or invoke `param_env.with_reveal_all()`.
1421 pub fn reveal_all() -> Self {
1422 Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
1425 /// Construct a trait environment with the given set of predicates.
1428 caller_bounds: &'tcx List<Predicate<'tcx>>,
1430 constness: hir::Constness,
1432 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
1435 pub fn with_user_facing(mut self) -> Self {
1436 self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
1441 pub fn with_constness(mut self, constness: hir::Constness) -> Self {
1442 self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
1447 pub fn with_const(mut self) -> Self {
1448 self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
1453 pub fn without_const(mut self) -> Self {
1454 self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
1459 pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
1460 *self = self.with_constness(constness.and(self.constness()))
1463 /// Returns a new parameter environment with the same clauses, but
1464 /// which "reveals" the true results of projections in all cases
1465 /// (even for associated types that are specializable). This is
1466 /// the desired behavior during codegen and certain other special
1467 /// contexts; normally though we want to use `Reveal::UserFacing`,
1468 /// which is the default.
1469 /// All opaque types in the caller_bounds of the `ParamEnv`
1470 /// will be normalized to their underlying types.
1471 /// See PR #65989 and issue #65918 for more details
1472 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1473 if self.packed.tag().reveal == traits::Reveal::All {
1478 tcx.normalize_opaque_types(self.caller_bounds()),
1484 /// Returns this same environment but with no caller bounds.
1486 pub fn without_caller_bounds(self) -> Self {
1487 Self::new(List::empty(), self.reveal(), self.constness())
1490 /// Creates a suitable environment in which to perform trait
1491 /// queries on the given value. When type-checking, this is simply
1492 /// the pair of the environment plus value. But when reveal is set to
1493 /// All, then if `value` does not reference any type parameters, we will
1494 /// pair it with the empty environment. This improves caching and is generally
1497 /// N.B., we preserve the environment when type-checking because it
1498 /// is possible for the user to have wacky where-clauses like
1499 /// `where Box<u32>: Copy`, which are clearly never
1500 /// satisfiable. We generally want to behave as if they were true,
1501 /// although the surrounding function is never reachable.
1502 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1503 match self.reveal() {
1504 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1507 if value.is_global() {
1508 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1510 ParamEnvAnd { param_env: self, value }
1517 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1518 // the constness of trait bounds is being propagated correctly.
1519 impl<'tcx> PolyTraitRef<'tcx> {
1521 pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
1522 self.map_bound(|trait_ref| ty::TraitPredicate {
1525 polarity: ty::ImplPolarity::Positive,
1530 pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
1531 self.with_constness(BoundConstness::NotConst)
1535 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1536 pub struct ParamEnvAnd<'tcx, T> {
1537 pub param_env: ParamEnv<'tcx>,
1541 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1542 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1543 (self.param_env, self.value)
1547 pub fn without_const(mut self) -> Self {
1548 self.param_env = self.param_env.without_const();
1553 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1555 T: HashStable<StableHashingContext<'a>>,
1557 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1558 let ParamEnvAnd { ref param_env, ref value } = *self;
1560 param_env.hash_stable(hcx, hasher);
1561 value.hash_stable(hcx, hasher);
1565 #[derive(Copy, Clone, Debug, HashStable)]
1566 pub struct Destructor {
1567 /// The `DefId` of the destructor method
1569 /// The constness of the destructor method
1570 pub constness: hir::Constness,
1574 #[derive(HashStable, TyEncodable, TyDecodable)]
1575 pub struct VariantFlags: u32 {
1576 const NO_VARIANT_FLAGS = 0;
1577 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1578 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1579 /// Indicates whether this variant was obtained as part of recovering from
1580 /// a syntactic error. May be incomplete or bogus.
1581 const IS_RECOVERED = 1 << 1;
1585 /// Definition of a variant -- a struct's fields or an enum variant.
1586 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1587 pub struct VariantDef {
1588 /// `DefId` that identifies the variant itself.
1589 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1591 /// `DefId` that identifies the variant's constructor.
1592 /// If this variant is a struct variant, then this is `None`.
1593 pub ctor_def_id: Option<DefId>,
1594 /// Variant or struct name.
1596 /// Discriminant of this variant.
1597 pub discr: VariantDiscr,
1598 /// Fields of this variant.
1599 pub fields: Vec<FieldDef>,
1600 /// Type of constructor of variant.
1601 pub ctor_kind: CtorKind,
1602 /// Flags of the variant (e.g. is field list non-exhaustive)?
1603 flags: VariantFlags,
1607 /// Creates a new `VariantDef`.
1609 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1610 /// represents an enum variant).
1612 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1613 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1615 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1616 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1617 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1618 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1619 /// built-in trait), and we do not want to load attributes twice.
1621 /// If someone speeds up attribute loading to not be a performance concern, they can
1622 /// remove this hack and use the constructor `DefId` everywhere.
1625 variant_did: Option<DefId>,
1626 ctor_def_id: Option<DefId>,
1627 discr: VariantDiscr,
1628 fields: Vec<FieldDef>,
1629 ctor_kind: CtorKind,
1633 is_field_list_non_exhaustive: bool,
1636 "VariantDef::new(name = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1637 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1638 name, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1641 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1642 if is_field_list_non_exhaustive {
1643 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1647 flags |= VariantFlags::IS_RECOVERED;
1651 def_id: variant_did.unwrap_or(parent_did),
1661 /// Is this field list non-exhaustive?
1663 pub fn is_field_list_non_exhaustive(&self) -> bool {
1664 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1667 /// Was this variant obtained as part of recovering from a syntactic error?
1669 pub fn is_recovered(&self) -> bool {
1670 self.flags.intersects(VariantFlags::IS_RECOVERED)
1673 /// Computes the `Ident` of this variant by looking up the `Span`
1674 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1675 Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1679 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1680 pub enum VariantDiscr {
1681 /// Explicit value for this variant, i.e., `X = 123`.
1682 /// The `DefId` corresponds to the embedded constant.
1685 /// The previous variant's discriminant plus one.
1686 /// For efficiency reasons, the distance from the
1687 /// last `Explicit` discriminant is being stored,
1688 /// or `0` for the first variant, if it has none.
1692 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1693 pub struct FieldDef {
1696 pub vis: Visibility,
1700 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1701 pub struct ReprFlags: u8 {
1702 const IS_C = 1 << 0;
1703 const IS_SIMD = 1 << 1;
1704 const IS_TRANSPARENT = 1 << 2;
1705 // Internal only for now. If true, don't reorder fields.
1706 const IS_LINEAR = 1 << 3;
1707 // If true, don't expose any niche to type's context.
1708 const HIDE_NICHE = 1 << 4;
1709 // If true, the type's layout can be randomized using
1710 // the seed stored in `ReprOptions.layout_seed`
1711 const RANDOMIZE_LAYOUT = 1 << 5;
1712 // Any of these flags being set prevent field reordering optimisation.
1713 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
1714 | ReprFlags::IS_SIMD.bits
1715 | ReprFlags::IS_LINEAR.bits;
1719 /// Represents the repr options provided by the user,
1720 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
1721 pub struct ReprOptions {
1722 pub int: Option<attr::IntType>,
1723 pub align: Option<Align>,
1724 pub pack: Option<Align>,
1725 pub flags: ReprFlags,
1726 /// The seed to be used for randomizing a type's layout
1728 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
1729 /// be the "most accurate" hash as it'd encompass the item and crate
1730 /// hash without loss, but it does pay the price of being larger.
1731 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
1732 /// purposes (primarily `-Z randomize-layout`)
1733 pub field_shuffle_seed: u64,
1737 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1738 let mut flags = ReprFlags::empty();
1739 let mut size = None;
1740 let mut max_align: Option<Align> = None;
1741 let mut min_pack: Option<Align> = None;
1743 // Generate a deterministically-derived seed from the item's path hash
1744 // to allow for cross-crate compilation to actually work
1745 let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
1747 // If the user defined a custom seed for layout randomization, xor the item's
1748 // path hash with the user defined seed, this will allowing determinism while
1749 // still allowing users to further randomize layout generation for e.g. fuzzing
1750 if let Some(user_seed) = tcx.sess.opts.debugging_opts.layout_seed {
1751 field_shuffle_seed ^= user_seed;
1754 for attr in tcx.get_attrs(did).iter() {
1755 for r in attr::find_repr_attrs(&tcx.sess, attr) {
1756 flags.insert(match r {
1757 attr::ReprC => ReprFlags::IS_C,
1758 attr::ReprPacked(pack) => {
1759 let pack = Align::from_bytes(pack as u64).unwrap();
1760 min_pack = Some(if let Some(min_pack) = min_pack {
1767 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1768 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
1769 attr::ReprSimd => ReprFlags::IS_SIMD,
1770 attr::ReprInt(i) => {
1774 attr::ReprAlign(align) => {
1775 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
1782 // If `-Z randomize-layout` was enabled for the type definition then we can
1783 // consider performing layout randomization
1784 if tcx.sess.opts.debugging_opts.randomize_layout {
1785 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1788 // This is here instead of layout because the choice must make it into metadata.
1789 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
1790 flags.insert(ReprFlags::IS_LINEAR);
1793 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1797 pub fn simd(&self) -> bool {
1798 self.flags.contains(ReprFlags::IS_SIMD)
1802 pub fn c(&self) -> bool {
1803 self.flags.contains(ReprFlags::IS_C)
1807 pub fn packed(&self) -> bool {
1812 pub fn transparent(&self) -> bool {
1813 self.flags.contains(ReprFlags::IS_TRANSPARENT)
1817 pub fn linear(&self) -> bool {
1818 self.flags.contains(ReprFlags::IS_LINEAR)
1822 pub fn hide_niche(&self) -> bool {
1823 self.flags.contains(ReprFlags::HIDE_NICHE)
1826 /// Returns the discriminant type, given these `repr` options.
1827 /// This must only be called on enums!
1828 pub fn discr_type(&self) -> attr::IntType {
1829 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1832 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
1833 /// layout" optimizations, such as representing `Foo<&T>` as a
1835 pub fn inhibit_enum_layout_opt(&self) -> bool {
1836 self.c() || self.int.is_some()
1839 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
1840 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
1841 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
1842 if let Some(pack) = self.pack {
1843 if pack.bytes() == 1 {
1848 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
1851 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
1852 /// was enabled for its declaration crate
1853 pub fn can_randomize_type_layout(&self) -> bool {
1854 !self.inhibit_struct_field_reordering_opt()
1855 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
1858 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
1859 pub fn inhibit_union_abi_opt(&self) -> bool {
1864 impl<'tcx> FieldDef {
1865 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
1866 /// typically obtained via the second field of [`TyKind::Adt`].
1867 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
1868 tcx.type_of(self.did).subst(tcx, subst)
1871 /// Computes the `Ident` of this variant by looking up the `Span`
1872 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1873 Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
1877 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
1879 #[derive(Debug, PartialEq, Eq)]
1880 pub enum ImplOverlapKind {
1881 /// These impls are always allowed to overlap.
1883 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1886 /// These impls are allowed to overlap, but that raises
1887 /// an issue #33140 future-compatibility warning.
1889 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
1890 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
1892 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
1893 /// that difference, making what reduces to the following set of impls:
1897 /// impl Trait for dyn Send + Sync {}
1898 /// impl Trait for dyn Sync + Send {}
1901 /// Obviously, once we made these types be identical, that code causes a coherence
1902 /// error and a fairly big headache for us. However, luckily for us, the trait
1903 /// `Trait` used in this case is basically a marker trait, and therefore having
1904 /// overlapping impls for it is sound.
1906 /// To handle this, we basically regard the trait as a marker trait, with an additional
1907 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
1908 /// it has the following restrictions:
1910 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
1912 /// 2. The trait-ref of both impls must be equal.
1913 /// 3. The trait-ref of both impls must be a trait object type consisting only of
1915 /// 4. Neither of the impls can have any where-clauses.
1917 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
1921 impl<'tcx> TyCtxt<'tcx> {
1922 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1923 self.typeck(self.hir().body_owner_def_id(body))
1926 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1927 self.associated_items(id)
1928 .in_definition_order()
1929 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
1932 fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
1933 self.hir().get_if_local(def_id).and_then(|node| node.ident())
1936 fn item_name_from_def_id(self, def_id: DefId) -> Option<Symbol> {
1937 if def_id.index == CRATE_DEF_INDEX {
1938 Some(self.crate_name(def_id.krate))
1940 let def_key = self.def_key(def_id);
1941 match def_key.disambiguated_data.data {
1942 // The name of a constructor is that of its parent.
1943 rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId {
1944 krate: def_id.krate,
1945 index: def_key.parent.unwrap(),
1947 _ => def_key.disambiguated_data.data.get_opt_name(),
1952 /// Look up the name of an item across crates. This does not look at HIR.
1954 /// When possible, this function should be used for cross-crate lookups over
1955 /// [`opt_item_name`] to avoid invalidating the incremental cache. If you
1956 /// need to handle items without a name, or HIR items that will not be
1957 /// serialized cross-crate, or if you need the span of the item, use
1958 /// [`opt_item_name`] instead.
1960 /// [`opt_item_name`]: Self::opt_item_name
1961 pub fn item_name(self, id: DefId) -> Symbol {
1962 // Look at cross-crate items first to avoid invalidating the incremental cache
1963 // unless we have to.
1964 self.item_name_from_def_id(id).unwrap_or_else(|| {
1965 bug!("item_name: no name for {:?}", self.def_path(id));
1969 /// Look up the name and span of an item or [`Node`].
1971 /// See [`item_name`][Self::item_name] for more information.
1972 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
1973 // Look at the HIR first so the span will be correct if this is a local item.
1974 self.item_name_from_hir(def_id)
1975 .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span))
1978 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
1979 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
1980 Some(self.associated_item(def_id))
1986 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
1987 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
1990 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
1994 .position(|field| self.hygienic_eq(ident, field.ident(self), variant.def_id))
1997 /// Returns `true` if the impls are the same polarity and the trait either
1998 /// has no items or is annotated `#[marker]` and prevents item overrides.
1999 pub fn impls_are_allowed_to_overlap(
2003 ) -> Option<ImplOverlapKind> {
2004 // If either trait impl references an error, they're allowed to overlap,
2005 // as one of them essentially doesn't exist.
2006 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2007 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2009 return Some(ImplOverlapKind::Permitted { marker: false });
2012 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2013 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2014 // `#[rustc_reservation_impl]` impls don't overlap with anything
2016 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2019 return Some(ImplOverlapKind::Permitted { marker: false });
2021 (ImplPolarity::Positive, ImplPolarity::Negative)
2022 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2023 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2025 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2030 (ImplPolarity::Positive, ImplPolarity::Positive)
2031 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2034 let is_marker_overlap = {
2035 let is_marker_impl = |def_id: DefId| -> bool {
2036 let trait_ref = self.impl_trait_ref(def_id);
2037 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2039 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2042 if is_marker_overlap {
2044 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2047 Some(ImplOverlapKind::Permitted { marker: true })
2049 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2050 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2051 if self_ty1 == self_ty2 {
2053 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2056 return Some(ImplOverlapKind::Issue33140);
2059 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2060 def_id1, def_id2, self_ty1, self_ty2
2066 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2071 /// Returns `ty::VariantDef` if `res` refers to a struct,
2072 /// or variant or their constructors, panics otherwise.
2073 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2075 Res::Def(DefKind::Variant, did) => {
2076 let enum_did = self.parent(did).unwrap();
2077 self.adt_def(enum_did).variant_with_id(did)
2079 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2080 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2081 let variant_did = self.parent(variant_ctor_did).unwrap();
2082 let enum_did = self.parent(variant_did).unwrap();
2083 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2085 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2086 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2087 self.adt_def(struct_did).non_enum_variant()
2089 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2093 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2094 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2096 ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
2099 | DefKind::AssocConst
2101 | DefKind::AnonConst
2102 | DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
2103 // If the caller wants `mir_for_ctfe` of a function they should not be using
2104 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2106 assert_eq!(def.const_param_did, None);
2107 self.optimized_mir(def.did)
2110 ty::InstanceDef::VtableShim(..)
2111 | ty::InstanceDef::ReifyShim(..)
2112 | ty::InstanceDef::Intrinsic(..)
2113 | ty::InstanceDef::FnPtrShim(..)
2114 | ty::InstanceDef::Virtual(..)
2115 | ty::InstanceDef::ClosureOnceShim { .. }
2116 | ty::InstanceDef::DropGlue(..)
2117 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2121 /// Gets the attributes of a definition.
2122 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
2123 if let Some(did) = did.as_local() {
2124 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2126 self.item_attrs(did)
2130 /// Determines whether an item is annotated with an attribute.
2131 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2132 self.sess.contains_name(&self.get_attrs(did), attr)
2135 /// Returns `true` if this is an `auto trait`.
2136 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2137 self.trait_def(trait_def_id).has_auto_impl
2140 /// Returns layout of a generator. Layout might be unavailable if the
2141 /// generator is tainted by errors.
2142 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2143 self.optimized_mir(def_id).generator_layout()
2146 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2147 /// If it implements no trait, returns `None`.
2148 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2149 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2152 /// If the given defid describes a method belonging to an impl, returns the
2153 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2154 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2155 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
2156 TraitContainer(_) => None,
2157 ImplContainer(def_id) => Some(def_id),
2161 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2162 /// with the name of the crate containing the impl.
2163 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2164 if let Some(impl_did) = impl_did.as_local() {
2165 Ok(self.def_span(impl_did))
2167 Err(self.crate_name(impl_did.krate))
2171 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2172 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2173 /// definition's parent/scope to perform comparison.
2174 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2175 // We could use `Ident::eq` here, but we deliberately don't. The name
2176 // comparison fails frequently, and we want to avoid the expensive
2177 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2178 use_name.name == def_name.name
2182 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2185 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2186 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2190 pub fn adjust_ident_and_get_scope(
2195 ) -> (Ident, DefId) {
2198 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2199 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2200 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2204 pub fn is_object_safe(self, key: DefId) -> bool {
2205 self.object_safety_violations(key).is_empty()
2209 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
2210 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
2211 let def_id = def_id.as_local()?;
2212 if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) {
2213 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2214 return match opaque_ty.origin {
2215 hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
2218 hir::OpaqueTyOrigin::TyAlias => None,
2225 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2227 ast::IntTy::Isize => IntTy::Isize,
2228 ast::IntTy::I8 => IntTy::I8,
2229 ast::IntTy::I16 => IntTy::I16,
2230 ast::IntTy::I32 => IntTy::I32,
2231 ast::IntTy::I64 => IntTy::I64,
2232 ast::IntTy::I128 => IntTy::I128,
2236 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2238 ast::UintTy::Usize => UintTy::Usize,
2239 ast::UintTy::U8 => UintTy::U8,
2240 ast::UintTy::U16 => UintTy::U16,
2241 ast::UintTy::U32 => UintTy::U32,
2242 ast::UintTy::U64 => UintTy::U64,
2243 ast::UintTy::U128 => UintTy::U128,
2247 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2249 ast::FloatTy::F32 => FloatTy::F32,
2250 ast::FloatTy::F64 => FloatTy::F64,
2254 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2256 IntTy::Isize => ast::IntTy::Isize,
2257 IntTy::I8 => ast::IntTy::I8,
2258 IntTy::I16 => ast::IntTy::I16,
2259 IntTy::I32 => ast::IntTy::I32,
2260 IntTy::I64 => ast::IntTy::I64,
2261 IntTy::I128 => ast::IntTy::I128,
2265 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2267 UintTy::Usize => ast::UintTy::Usize,
2268 UintTy::U8 => ast::UintTy::U8,
2269 UintTy::U16 => ast::UintTy::U16,
2270 UintTy::U32 => ast::UintTy::U32,
2271 UintTy::U64 => ast::UintTy::U64,
2272 UintTy::U128 => ast::UintTy::U128,
2276 pub fn provide(providers: &mut ty::query::Providers) {
2277 closure::provide(providers);
2278 context::provide(providers);
2279 erase_regions::provide(providers);
2280 layout::provide(providers);
2281 util::provide(providers);
2282 print::provide(providers);
2283 super::util::bug::provide(providers);
2284 super::middle::provide(providers);
2285 *providers = ty::query::Providers {
2286 trait_impls_of: trait_def::trait_impls_of_provider,
2287 type_uninhabited_from: inhabitedness::type_uninhabited_from,
2288 const_param_default: consts::const_param_default,
2289 vtable_allocation: vtable::vtable_allocation_provider,
2294 /// A map for the local crate mapping each type to a vector of its
2295 /// inherent impls. This is not meant to be used outside of coherence;
2296 /// rather, you should request the vector for a specific type via
2297 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2298 /// (constructing this map requires touching the entire crate).
2299 #[derive(Clone, Debug, Default, HashStable)]
2300 pub struct CrateInherentImpls {
2301 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2304 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2305 pub struct SymbolName<'tcx> {
2306 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2307 pub name: &'tcx str,
2310 impl<'tcx> SymbolName<'tcx> {
2311 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2313 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2318 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2319 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2320 fmt::Display::fmt(&self.name, fmt)
2324 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2325 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2326 fmt::Display::fmt(&self.name, fmt)
2330 #[derive(Debug, Default, Copy, Clone)]
2331 pub struct FoundRelationships {
2332 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2333 /// obligation, where:
2335 /// * `Foo` is not `Sized`
2336 /// * `(): Foo` may be satisfied
2337 pub self_in_trait: bool,
2338 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2339 /// _>::AssocType = ?T`