//! Defines how the compiler represents types internally. //! //! Two important entities in this module are: //! //! - [`rustc_middle::ty::Ty`], used to represent the semantics of a type. //! - [`rustc_middle::ty::TyCtxt`], the central data structure in the compiler. //! //! For more information, see ["The `ty` module: representing types"] in the ructc-dev-guide. //! //! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html pub use self::fold::{TypeFoldable, TypeFolder, TypeVisitor}; pub use self::AssocItemContainer::*; pub use self::BorrowKind::*; pub use self::IntVarValue::*; pub use self::Variance::*; pub use adt::*; pub use assoc::*; pub use generics::*; pub use vtable::*; use crate::hir::exports::ExportMap; use crate::ich::StableHashingContext; use crate::middle::cstore::CrateStoreDyn; use crate::mir::{Body, GeneratorLayout}; use crate::traits::{self, Reveal}; use crate::ty; use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef}; use crate::ty::util::Discr; use rustc_ast as ast; use rustc_attr as attr; use rustc_data_structures::fx::{FxHashMap, FxHashSet}; use rustc_data_structures::stable_hasher::{HashStable, StableHasher}; use rustc_data_structures::tagged_ptr::CopyTaggedPtr; use rustc_hir as hir; use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res}; use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap, CRATE_DEF_INDEX}; use rustc_hir::Node; use rustc_macros::HashStable; use rustc_span::symbol::{kw, Ident, Symbol}; use rustc_span::Span; use rustc_target::abi::Align; use std::cmp::Ordering; use std::collections::BTreeMap; use std::hash::{Hash, Hasher}; use std::ops::ControlFlow; use std::{fmt, ptr, str}; pub use crate::ty::diagnostics::*; pub use rustc_type_ir::InferTy::*; pub use rustc_type_ir::*; pub use self::binding::BindingMode; pub use self::binding::BindingMode::*; pub use self::closure::{ is_ancestor_or_same_capture, place_to_string_for_capture, BorrowKind, CaptureInfo, CapturedPlace, ClosureKind, MinCaptureInformationMap, MinCaptureList, RootVariableMinCaptureList, UpvarBorrow, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath, CAPTURE_STRUCT_LOCAL, }; pub use self::consts::{Const, ConstInt, ConstKind, InferConst, ScalarInt, Unevaluated, ValTree}; pub use self::context::{ tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorInteriorTypeCause, GlobalCtxt, Lift, OnDiskCache, TyCtxt, TypeckResults, UserType, UserTypeAnnotationIndex, }; pub use self::instance::{Instance, InstanceDef}; pub use self::list::List; pub use self::sty::BoundRegionKind::*; pub use self::sty::RegionKind::*; pub use self::sty::TyKind::*; pub use self::sty::{ Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind, CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBoundRegion, ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig, GeneratorSubsts, GeneratorSubstsParts, ParamConst, ParamTy, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig, PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut, UpvarSubsts, VarianceDiagInfo, VarianceDiagMutKind, }; pub use self::trait_def::TraitDef; pub mod _match; pub mod adjustment; pub mod binding; pub mod cast; pub mod codec; pub mod error; pub mod fast_reject; pub mod flags; pub mod fold; pub mod inhabitedness; pub mod layout; pub mod normalize_erasing_regions; pub mod outlives; pub mod print; pub mod query; pub mod relate; pub mod subst; pub mod trait_def; pub mod util; pub mod vtable; pub mod walk; mod adt; mod assoc; mod closure; mod consts; mod context; mod diagnostics; mod erase_regions; mod generics; mod instance; mod list; mod structural_impls; mod sty; // Data types #[derive(Debug)] pub struct ResolverOutputs { pub definitions: rustc_hir::definitions::Definitions, pub cstore: Box, pub visibilities: FxHashMap, pub extern_crate_map: FxHashMap, pub maybe_unused_trait_imports: FxHashSet, pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>, pub export_map: ExportMap, pub glob_map: FxHashMap>, /// Extern prelude entries. The value is `true` if the entry was introduced /// via `extern crate` item and not `--extern` option or compiler built-in. pub extern_prelude: FxHashMap, pub main_def: Option, pub trait_impls: BTreeMap>, /// A list of proc macro LocalDefIds, written out in the order in which /// they are declared in the static array generated by proc_macro_harness. pub proc_macros: Vec, /// Mapping from ident span to path span for paths that don't exist as written, but that /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`. pub confused_type_with_std_module: FxHashMap, } #[derive(Clone, Copy, Debug)] pub struct MainDefinition { pub res: Res, pub is_import: bool, pub span: Span, } impl MainDefinition { pub fn opt_fn_def_id(self) -> Option { if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None } } } /// The "header" of an impl is everything outside the body: a Self type, a trait /// ref (in the case of a trait impl), and a set of predicates (from the /// bounds / where-clauses). #[derive(Clone, Debug, TypeFoldable)] pub struct ImplHeader<'tcx> { pub impl_def_id: DefId, pub self_ty: Ty<'tcx>, pub trait_ref: Option>, pub predicates: Vec>, } #[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)] pub enum ImplPolarity { /// `impl Trait for Type` Positive, /// `impl !Trait for Type` Negative, /// `#[rustc_reservation_impl] impl Trait for Type` /// /// This is a "stability hack", not a real Rust feature. /// See #64631 for details. Reservation, } #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)] pub enum Visibility { /// Visible everywhere (including in other crates). Public, /// Visible only in the given crate-local module. Restricted(DefId), /// Not visible anywhere in the local crate. This is the visibility of private external items. Invisible, } #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)] pub enum BoundConstness { /// `T: Trait` NotConst, /// `T: ~const Trait` /// /// Requires resolving to const only when we are in a const context. ConstIfConst, } impl fmt::Display for BoundConstness { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { match self { Self::NotConst => f.write_str("normal"), Self::ConstIfConst => f.write_str("`~const`"), } } } #[derive( Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable, TypeFoldable )] pub struct ClosureSizeProfileData<'tcx> { /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields` pub before_feature_tys: Ty<'tcx>, /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields` pub after_feature_tys: Ty<'tcx>, } pub trait DefIdTree: Copy { fn parent(self, id: DefId) -> Option; fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool { if descendant.krate != ancestor.krate { return false; } while descendant != ancestor { match self.parent(descendant) { Some(parent) => descendant = parent, None => return false, } } true } } impl<'tcx> DefIdTree for TyCtxt<'tcx> { fn parent(self, id: DefId) -> Option { self.def_key(id).parent.map(|index| DefId { index, ..id }) } } impl Visibility { pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self { match visibility.node { hir::VisibilityKind::Public => Visibility::Public, hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)), hir::VisibilityKind::Restricted { ref path, .. } => match path.res { // If there is no resolution, `resolve` will have already reported an error, so // assume that the visibility is public to avoid reporting more privacy errors. Res::Err => Visibility::Public, def => Visibility::Restricted(def.def_id()), }, hir::VisibilityKind::Inherited => { Visibility::Restricted(tcx.parent_module(id).to_def_id()) } } } /// Returns `true` if an item with this visibility is accessible from the given block. pub fn is_accessible_from(self, module: DefId, tree: T) -> bool { let restriction = match self { // Public items are visible everywhere. Visibility::Public => return true, // Private items from other crates are visible nowhere. Visibility::Invisible => return false, // Restricted items are visible in an arbitrary local module. Visibility::Restricted(other) if other.krate != module.krate => return false, Visibility::Restricted(module) => module, }; tree.is_descendant_of(module, restriction) } /// Returns `true` if this visibility is at least as accessible as the given visibility pub fn is_at_least(self, vis: Visibility, tree: T) -> bool { let vis_restriction = match vis { Visibility::Public => return self == Visibility::Public, Visibility::Invisible => return true, Visibility::Restricted(module) => module, }; self.is_accessible_from(vis_restriction, tree) } // Returns `true` if this item is visible anywhere in the local crate. pub fn is_visible_locally(self) -> bool { match self { Visibility::Public => true, Visibility::Restricted(def_id) => def_id.is_local(), Visibility::Invisible => false, } } } /// The crate variances map is computed during typeck and contains the /// variance of every item in the local crate. You should not use it /// directly, because to do so will make your pass dependent on the /// HIR of every item in the local crate. Instead, use /// `tcx.variances_of()` to get the variance for a *particular* /// item. #[derive(HashStable, Debug)] pub struct CrateVariancesMap<'tcx> { /// For each item with generics, maps to a vector of the variance /// of its generics. If an item has no generics, it will have no /// entry. pub variances: FxHashMap, } // Contains information needed to resolve types and (in the future) look up // the types of AST nodes. #[derive(Copy, Clone, PartialEq, Eq, Hash)] pub struct CReaderCacheKey { pub cnum: Option, pub pos: usize, } #[allow(rustc::usage_of_ty_tykind)] pub struct TyS<'tcx> { /// This field shouldn't be used directly and may be removed in the future. /// Use `TyS::kind()` instead. kind: TyKind<'tcx>, /// This field shouldn't be used directly and may be removed in the future. /// Use `TyS::flags()` instead. flags: TypeFlags, /// This is a kind of confusing thing: it stores the smallest /// binder such that /// /// (a) the binder itself captures nothing but /// (b) all the late-bound things within the type are captured /// by some sub-binder. /// /// So, for a type without any late-bound things, like `u32`, this /// will be *innermost*, because that is the innermost binder that /// captures nothing. But for a type `&'D u32`, where `'D` is a /// late-bound region with De Bruijn index `D`, this would be `D + 1` /// -- the binder itself does not capture `D`, but `D` is captured /// by an inner binder. /// /// We call this concept an "exclusive" binder `D` because all /// De Bruijn indices within the type are contained within `0..D` /// (exclusive). outer_exclusive_binder: ty::DebruijnIndex, } impl<'tcx> TyS<'tcx> { /// A constructor used only for internal testing. #[allow(rustc::usage_of_ty_tykind)] pub fn make_for_test( kind: TyKind<'tcx>, flags: TypeFlags, outer_exclusive_binder: ty::DebruijnIndex, ) -> TyS<'tcx> { TyS { kind, flags, outer_exclusive_binder } } } // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger. #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))] static_assert_size!(TyS<'_>, 40); impl<'tcx> Ord for TyS<'tcx> { fn cmp(&self, other: &TyS<'tcx>) -> Ordering { self.kind().cmp(other.kind()) } } impl<'tcx> PartialOrd for TyS<'tcx> { fn partial_cmp(&self, other: &TyS<'tcx>) -> Option { Some(self.kind().cmp(other.kind())) } } impl<'tcx> PartialEq for TyS<'tcx> { #[inline] fn eq(&self, other: &TyS<'tcx>) -> bool { ptr::eq(self, other) } } impl<'tcx> Eq for TyS<'tcx> {} impl<'tcx> Hash for TyS<'tcx> { fn hash(&self, s: &mut H) { (self as *const TyS<'_>).hash(s) } } impl<'a, 'tcx> HashStable> for TyS<'tcx> { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { let ty::TyS { ref kind, // The other fields just provide fast access to information that is // also contained in `kind`, so no need to hash them. flags: _, outer_exclusive_binder: _, } = *self; kind.hash_stable(hcx, hasher); } } #[rustc_diagnostic_item = "Ty"] pub type Ty<'tcx> = &'tcx TyS<'tcx>; impl ty::EarlyBoundRegion { /// Does this early bound region have a name? Early bound regions normally /// always have names except when using anonymous lifetimes (`'_`). pub fn has_name(&self) -> bool { self.name != kw::UnderscoreLifetime } } #[derive(Debug)] crate struct PredicateInner<'tcx> { kind: Binder<'tcx, PredicateKind<'tcx>>, flags: TypeFlags, /// See the comment for the corresponding field of [TyS]. outer_exclusive_binder: ty::DebruijnIndex, } #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))] static_assert_size!(PredicateInner<'_>, 48); #[derive(Clone, Copy, Lift)] pub struct Predicate<'tcx> { inner: &'tcx PredicateInner<'tcx>, } impl<'tcx> PartialEq for Predicate<'tcx> { fn eq(&self, other: &Self) -> bool { // `self.kind` is always interned. ptr::eq(self.inner, other.inner) } } impl Hash for Predicate<'_> { fn hash(&self, s: &mut H) { (self.inner as *const PredicateInner<'_>).hash(s) } } impl<'tcx> Eq for Predicate<'tcx> {} impl<'tcx> Predicate<'tcx> { /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`. #[inline] pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> { self.inner.kind } } impl<'a, 'tcx> HashStable> for Predicate<'tcx> { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { let PredicateInner { ref kind, // The other fields just provide fast access to information that is // also contained in `kind`, so no need to hash them. flags: _, outer_exclusive_binder: _, } = self.inner; kind.hash_stable(hcx, hasher); } } #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] pub enum PredicateKind<'tcx> { /// Corresponds to `where Foo: Bar`. `Foo` here would be /// the `Self` type of the trait reference and `A`, `B`, and `C` /// would be the type parameters. Trait(TraitPredicate<'tcx>), /// `where 'a: 'b` RegionOutlives(RegionOutlivesPredicate<'tcx>), /// `where T: 'a` TypeOutlives(TypeOutlivesPredicate<'tcx>), /// `where ::Name == X`, approximately. /// See the `ProjectionPredicate` struct for details. Projection(ProjectionPredicate<'tcx>), /// No syntax: `T` well-formed. WellFormed(GenericArg<'tcx>), /// Trait must be object-safe. ObjectSafe(DefId), /// No direct syntax. May be thought of as `where T: FnFoo<...>` /// for some substitutions `...` and `T` being a closure type. /// Satisfied (or refuted) once we know the closure's kind. ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind), /// `T1 <: T2` /// /// This obligation is created most often when we have two /// unresolved type variables and hence don't have enough /// information to process the subtyping obligation yet. Subtype(SubtypePredicate<'tcx>), /// `T1` coerced to `T2` /// /// Like a subtyping obligation, this is created most often /// when we have two unresolved type variables and hence /// don't have enough information to process the coercion /// obligation yet. At the moment, we actually process coercions /// very much like subtyping and don't handle the full coercion /// logic. Coerce(CoercePredicate<'tcx>), /// Constant initializer must evaluate successfully. ConstEvaluatable(ty::Unevaluated<'tcx, ()>), /// Constants must be equal. The first component is the const that is expected. ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>), /// Represents a type found in the environment that we can use for implied bounds. /// /// Only used for Chalk. TypeWellFormedFromEnv(Ty<'tcx>), } /// The crate outlives map is computed during typeck and contains the /// outlives of every item in the local crate. You should not use it /// directly, because to do so will make your pass dependent on the /// HIR of every item in the local crate. Instead, use /// `tcx.inferred_outlives_of()` to get the outlives for a *particular* /// item. #[derive(HashStable, Debug)] pub struct CratePredicatesMap<'tcx> { /// For each struct with outlive bounds, maps to a vector of the /// predicate of its outlive bounds. If an item has no outlives /// bounds, it will have no entry. pub predicates: FxHashMap, Span)]>, } impl<'tcx> Predicate<'tcx> { /// Performs a substitution suitable for going from a /// poly-trait-ref to supertraits that must hold if that /// poly-trait-ref holds. This is slightly different from a normal /// substitution in terms of what happens with bound regions. See /// lengthy comment below for details. pub fn subst_supertrait( self, tcx: TyCtxt<'tcx>, trait_ref: &ty::PolyTraitRef<'tcx>, ) -> Predicate<'tcx> { // The interaction between HRTB and supertraits is not entirely // obvious. Let me walk you (and myself) through an example. // // Let's start with an easy case. Consider two traits: // // trait Foo<'a>: Bar<'a,'a> { } // trait Bar<'b,'c> { } // // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we // knew that `Foo<'x>` (for any 'x) then we also know that // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from // normal substitution. // // In terms of why this is sound, the idea is that whenever there // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>` // holds. So if there is an impl of `T:Foo<'a>` that applies to // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all // `'a`. // // Another example to be careful of is this: // // trait Foo1<'a>: for<'b> Bar1<'a,'b> { } // trait Bar1<'b,'c> { } // // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know? // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The // reason is similar to the previous example: any impl of // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So // basically we would want to collapse the bound lifetimes from // the input (`trait_ref`) and the supertraits. // // To achieve this in practice is fairly straightforward. Let's // consider the more complicated scenario: // // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x` // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`, // where both `'x` and `'b` would have a DB index of 1. // The substitution from the input trait-ref is therefore going to be // `'a => 'x` (where `'x` has a DB index of 1). // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an // early-bound parameter and `'b' is a late-bound parameter with a // DB index of 1. // - If we replace `'a` with `'x` from the input, it too will have // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>` // just as we wanted. // // There is only one catch. If we just apply the substitution `'a // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will // adjust the DB index because we substituting into a binder (it // tries to be so smart...) resulting in `for<'x> for<'b> // Bar1<'x,'b>` (we have no syntax for this, so use your // imagination). Basically the 'x will have DB index of 2 and 'b // will have DB index of 1. Not quite what we want. So we apply // the substitution to the *contents* of the trait reference, // rather than the trait reference itself (put another way, the // substitution code expects equal binding levels in the values // from the substitution and the value being substituted into, and // this trick achieves that). // Working through the second example: // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0] // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0] // We want to end up with: // for<'x, 'b> T: Bar1<'^0.0, '^0.1> // To do this: // 1) We must shift all bound vars in predicate by the length // of trait ref's bound vars. So, we would end up with predicate like // Self: Bar1<'a, '^0.1> // 2) We can then apply the trait substs to this, ending up with // T: Bar1<'^0.0, '^0.1> // 3) Finally, to create the final bound vars, we concatenate the bound // vars of the trait ref with those of the predicate: // ['x, 'b] let bound_pred = self.kind(); let pred_bound_vars = bound_pred.bound_vars(); let trait_bound_vars = trait_ref.bound_vars(); // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1> let shifted_pred = tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder()); // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1> let new = shifted_pred.subst(tcx, trait_ref.skip_binder().substs); // 3) ['x] + ['b] -> ['x, 'b] let bound_vars = tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars)); tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars)) } } #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] pub struct TraitPredicate<'tcx> { pub trait_ref: TraitRef<'tcx>, pub constness: BoundConstness, } pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>; impl<'tcx> TraitPredicate<'tcx> { pub fn def_id(self) -> DefId { self.trait_ref.def_id } pub fn self_ty(self) -> Ty<'tcx> { self.trait_ref.self_ty() } } impl<'tcx> PolyTraitPredicate<'tcx> { pub fn def_id(self) -> DefId { // Ok to skip binder since trait `DefId` does not care about regions. self.skip_binder().def_id() } pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> { self.map_bound(|trait_ref| trait_ref.self_ty()) } } #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] pub struct OutlivesPredicate(pub A, pub B); // `A: B` pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate, ty::Region<'tcx>>; pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate, ty::Region<'tcx>>; pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>; pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>; /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates /// whether the `a` type is the type that we should label as "expected" when /// presenting user diagnostics. #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] pub struct SubtypePredicate<'tcx> { pub a_is_expected: bool, pub a: Ty<'tcx>, pub b: Ty<'tcx>, } pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>; /// Encodes that we have to coerce *from* the `a` type to the `b` type. #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] pub struct CoercePredicate<'tcx> { pub a: Ty<'tcx>, pub b: Ty<'tcx>, } pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>; /// This kind of predicate has no *direct* correspondent in the /// syntax, but it roughly corresponds to the syntactic forms: /// /// 1. `T: TraitRef<..., Item = Type>` /// 2. `>::Item == Type` (NYI) /// /// In particular, form #1 is "desugared" to the combination of a /// normal trait predicate (`T: TraitRef<...>`) and one of these /// predicates. Form #2 is a broader form in that it also permits /// equality between arbitrary types. Processing an instance of /// Form #2 eventually yields one of these `ProjectionPredicate` /// instances to normalize the LHS. #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable)] pub struct ProjectionPredicate<'tcx> { pub projection_ty: ProjectionTy<'tcx>, pub ty: Ty<'tcx>, } pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>; impl<'tcx> PolyProjectionPredicate<'tcx> { /// Returns the `DefId` of the trait of the associated item being projected. #[inline] pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId { self.skip_binder().projection_ty.trait_def_id(tcx) } /// Get the [PolyTraitRef] required for this projection to be well formed. /// Note that for generic associated types the predicates of the associated /// type also need to be checked. #[inline] pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> { // Note: unlike with `TraitRef::to_poly_trait_ref()`, // `self.0.trait_ref` is permitted to have escaping regions. // This is because here `self` has a `Binder` and so does our // return value, so we are preserving the number of binding // levels. self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx)) } pub fn ty(&self) -> Binder<'tcx, Ty<'tcx>> { self.map_bound(|predicate| predicate.ty) } /// The `DefId` of the `TraitItem` for the associated type. /// /// Note that this is not the `DefId` of the `TraitRef` containing this /// associated type, which is in `tcx.associated_item(projection_def_id()).container`. pub fn projection_def_id(&self) -> DefId { // Ok to skip binder since trait `DefId` does not care about regions. self.skip_binder().projection_ty.item_def_id } } pub trait ToPolyTraitRef<'tcx> { fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>; } impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> { fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> { self.map_bound_ref(|trait_pred| trait_pred.trait_ref) } } pub trait ToPredicate<'tcx> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>; } impl ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> { #[inline(always)] fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { tcx.mk_predicate(self) } } impl<'tcx> ToPredicate<'tcx> for ConstnessAnd> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { self.value .map_bound(|trait_ref| { PredicateKind::Trait(ty::TraitPredicate { trait_ref, constness: self.constness }) }) .to_predicate(tcx) } } impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { self.map_bound(PredicateKind::Trait).to_predicate(tcx) } } impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx) } } impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx) } } impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { self.map_bound(PredicateKind::Projection).to_predicate(tcx) } } impl<'tcx> Predicate<'tcx> { pub fn to_opt_poly_trait_ref(self) -> Option>> { let predicate = self.kind(); match predicate.skip_binder() { PredicateKind::Trait(t) => { Some(ConstnessAnd { constness: t.constness, value: predicate.rebind(t.trait_ref) }) } PredicateKind::Projection(..) | PredicateKind::Subtype(..) | PredicateKind::Coerce(..) | PredicateKind::RegionOutlives(..) | PredicateKind::WellFormed(..) | PredicateKind::ObjectSafe(..) | PredicateKind::ClosureKind(..) | PredicateKind::TypeOutlives(..) | PredicateKind::ConstEvaluatable(..) | PredicateKind::ConstEquate(..) | PredicateKind::TypeWellFormedFromEnv(..) => None, } } pub fn to_opt_type_outlives(self) -> Option> { let predicate = self.kind(); match predicate.skip_binder() { PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)), PredicateKind::Trait(..) | PredicateKind::Projection(..) | PredicateKind::Subtype(..) | PredicateKind::Coerce(..) | PredicateKind::RegionOutlives(..) | PredicateKind::WellFormed(..) | PredicateKind::ObjectSafe(..) | PredicateKind::ClosureKind(..) | PredicateKind::ConstEvaluatable(..) | PredicateKind::ConstEquate(..) | PredicateKind::TypeWellFormedFromEnv(..) => None, } } } /// Represents the bounds declared on a particular set of type /// parameters. Should eventually be generalized into a flag list of /// where-clauses. You can obtain an `InstantiatedPredicates` list from a /// `GenericPredicates` by using the `instantiate` method. Note that this method /// reflects an important semantic invariant of `InstantiatedPredicates`: while /// the `GenericPredicates` are expressed in terms of the bound type /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance /// represented a set of bounds for some particular instantiation, /// meaning that the generic parameters have been substituted with /// their values. /// /// Example: /// /// struct Foo> { ... } /// /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like /// `[[], [U:Bar]]`. Now if there were some particular reference /// like `Foo`, then the `InstantiatedPredicates` would be `[[], /// [usize:Bar]]`. #[derive(Clone, Debug, TypeFoldable)] pub struct InstantiatedPredicates<'tcx> { pub predicates: Vec>, pub spans: Vec, } impl<'tcx> InstantiatedPredicates<'tcx> { pub fn empty() -> InstantiatedPredicates<'tcx> { InstantiatedPredicates { predicates: vec![], spans: vec![] } } pub fn is_empty(&self) -> bool { self.predicates.is_empty() } } #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable, TypeFoldable)] pub struct OpaqueTypeKey<'tcx> { pub def_id: DefId, pub substs: SubstsRef<'tcx>, } rustc_index::newtype_index! { /// "Universes" are used during type- and trait-checking in the /// presence of `for<..>` binders to control what sets of names are /// visible. Universes are arranged into a tree: the root universe /// contains names that are always visible. Each child then adds a new /// set of names that are visible, in addition to those of its parent. /// We say that the child universe "extends" the parent universe with /// new names. /// /// To make this more concrete, consider this program: /// /// ``` /// struct Foo { } /// fn bar(x: T) { /// let y: for<'a> fn(&'a u8, Foo) = ...; /// } /// ``` /// /// The struct name `Foo` is in the root universe U0. But the type /// parameter `T`, introduced on `bar`, is in an extended universe U1 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside /// of `bar`, we cannot name `T`. Then, within the type of `y`, the /// region `'a` is in a universe U2 that extends U1, because we can /// name it inside the fn type but not outside. /// /// Universes are used to do type- and trait-checking around these /// "forall" binders (also called **universal quantification**). The /// idea is that when, in the body of `bar`, we refer to `T` as a /// type, we aren't referring to any type in particular, but rather a /// kind of "fresh" type that is distinct from all other types we have /// actually declared. This is called a **placeholder** type, and we /// use universes to talk about this. In other words, a type name in /// universe 0 always corresponds to some "ground" type that the user /// declared, but a type name in a non-zero universe is a placeholder /// type -- an idealized representative of "types in general" that we /// use for checking generic functions. pub struct UniverseIndex { derive [HashStable] DEBUG_FORMAT = "U{}", } } impl UniverseIndex { pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0); /// Returns the "next" universe index in order -- this new index /// is considered to extend all previous universes. This /// corresponds to entering a `forall` quantifier. So, for /// example, suppose we have this type in universe `U`: /// /// ``` /// for<'a> fn(&'a u32) /// ``` /// /// Once we "enter" into this `for<'a>` quantifier, we are in a /// new universe that extends `U` -- in this new universe, we can /// name the region `'a`, but that region was not nameable from /// `U` because it was not in scope there. pub fn next_universe(self) -> UniverseIndex { UniverseIndex::from_u32(self.private.checked_add(1).unwrap()) } /// Returns `true` if `self` can name a name from `other` -- in other words, /// if the set of names in `self` is a superset of those in /// `other` (`self >= other`). pub fn can_name(self, other: UniverseIndex) -> bool { self.private >= other.private } /// Returns `true` if `self` cannot name some names from `other` -- in other /// words, if the set of names in `self` is a strict subset of /// those in `other` (`self < other`). pub fn cannot_name(self, other: UniverseIndex) -> bool { self.private < other.private } } /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are /// identified by both a universe, as well as a name residing within that universe. Distinct bound /// regions/types/consts within the same universe simply have an unknown relationship to one /// another. #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)] pub struct Placeholder { pub universe: UniverseIndex, pub name: T, } impl<'a, T> HashStable> for Placeholder where T: HashStable>, { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { self.universe.hash_stable(hcx, hasher); self.name.hash_stable(hcx, hasher); } } pub type PlaceholderRegion = Placeholder; pub type PlaceholderType = Placeholder; #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)] #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)] pub struct BoundConst<'tcx> { pub var: BoundVar, pub ty: Ty<'tcx>, } pub type PlaceholderConst<'tcx> = Placeholder>; /// A `DefId` which, in case it is a const argument, is potentially bundled with /// the `DefId` of the generic parameter it instantiates. /// /// This is used to avoid calls to `type_of` for const arguments during typeck /// which cause cycle errors. /// /// ```rust /// struct A; /// impl A { /// fn foo(&self) -> [u8; N] { [0; N] } /// // ^ const parameter /// } /// struct B; /// impl B { /// fn foo(&self) -> usize { 42 } /// // ^ const parameter /// } /// /// fn main() { /// let a = A; /// let _b = a.foo::<{ 3 + 7 }>(); /// // ^^^^^^^^^ const argument /// } /// ``` /// /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know /// which `foo` is used until we know the type of `a`. /// /// We only know the type of `a` once we are inside of `typeck(main)`. /// We also end up normalizing the type of `_b` during `typeck(main)` which /// requires us to evaluate the const argument. /// /// To evaluate that const argument we need to know its type, /// which we would get using `type_of(const_arg)`. This requires us to /// resolve `foo` as it can be either `usize` or `u8` in this example. /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`, /// which results in a cycle. /// /// In short we must not call `type_of(const_arg)` during `typeck(main)`. /// /// When first creating the `ty::Const` of the const argument inside of `typeck` we have /// already resolved `foo` so we know which const parameter this argument instantiates. /// This means that we also know the expected result of `type_of(const_arg)` even if we /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is /// trivial to compute. /// /// If we now want to use that constant in a place which potentionally needs its type /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`, /// except that instead of a `Ty` we bundle the `DefId` of the const parameter. /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some` /// to get the type of `did`. #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)] #[derive(PartialEq, Eq, PartialOrd, Ord)] #[derive(Hash, HashStable)] pub struct WithOptConstParam { pub did: T, /// The `DefId` of the corresponding generic parameter in case `did` is /// a const argument. /// /// Note that even if `did` is a const argument, this may still be `None`. /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)` /// to potentially update `param_did` in the case it is `None`. pub const_param_did: Option, } impl WithOptConstParam { /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`. #[inline(always)] pub fn unknown(did: T) -> WithOptConstParam { WithOptConstParam { did, const_param_did: None } } } impl WithOptConstParam { /// Returns `Some((did, param_did))` if `def_id` is a const argument, /// `None` otherwise. #[inline(always)] pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> { tcx.opt_const_param_of(did).map(|param_did| (did, param_did)) } /// In case `self` is unknown but `self.did` is a const argument, this returns /// a `WithOptConstParam` with the correct `const_param_did`. #[inline(always)] pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option> { if self.const_param_did.is_none() { if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) { return Some(WithOptConstParam { did: self.did, const_param_did }); } } None } pub fn to_global(self) -> WithOptConstParam { WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did } } pub fn def_id_for_type_of(self) -> DefId { if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() } } } impl WithOptConstParam { pub fn as_local(self) -> Option> { self.did .as_local() .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did }) } pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> { if let Some(param_did) = self.const_param_did { if let Some(did) = self.did.as_local() { return Some((did, param_did)); } } None } pub fn is_local(self) -> bool { self.did.is_local() } pub fn def_id_for_type_of(self) -> DefId { self.const_param_did.unwrap_or(self.did) } } /// When type checking, we use the `ParamEnv` to track /// details about the set of where-clauses that are in scope at this /// particular point. #[derive(Copy, Clone, Hash, PartialEq, Eq)] pub struct ParamEnv<'tcx> { /// This packs both caller bounds and the reveal enum into one pointer. /// /// Caller bounds are `Obligation`s that the caller must satisfy. This is /// basically the set of bounds on the in-scope type parameters, translated /// into `Obligation`s, and elaborated and normalized. /// /// Use the `caller_bounds()` method to access. /// /// Typically, this is `Reveal::UserFacing`, but during codegen we /// want `Reveal::All`. /// /// Note: This is packed, use the reveal() method to access it. packed: CopyTaggedPtr<&'tcx List>, traits::Reveal, true>, } unsafe impl rustc_data_structures::tagged_ptr::Tag for traits::Reveal { const BITS: usize = 1; #[inline] fn into_usize(self) -> usize { match self { traits::Reveal::UserFacing => 0, traits::Reveal::All => 1, } } #[inline] unsafe fn from_usize(ptr: usize) -> Self { match ptr { 0 => traits::Reveal::UserFacing, 1 => traits::Reveal::All, _ => std::hint::unreachable_unchecked(), } } } impl<'tcx> fmt::Debug for ParamEnv<'tcx> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { f.debug_struct("ParamEnv") .field("caller_bounds", &self.caller_bounds()) .field("reveal", &self.reveal()) .finish() } } impl<'a, 'tcx> HashStable> for ParamEnv<'tcx> { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { self.caller_bounds().hash_stable(hcx, hasher); self.reveal().hash_stable(hcx, hasher); } } impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> { fn super_fold_with>(self, folder: &mut F) -> Self { ParamEnv::new(self.caller_bounds().fold_with(folder), self.reveal().fold_with(folder)) } fn super_visit_with>(&self, visitor: &mut V) -> ControlFlow { self.caller_bounds().visit_with(visitor)?; self.reveal().visit_with(visitor) } } impl<'tcx> ParamEnv<'tcx> { /// Construct a trait environment suitable for contexts where /// there are no where-clauses in scope. Hidden types (like `impl /// Trait`) are left hidden, so this is suitable for ordinary /// type-checking. #[inline] pub fn empty() -> Self { Self::new(List::empty(), Reveal::UserFacing) } #[inline] pub fn caller_bounds(self) -> &'tcx List> { self.packed.pointer() } #[inline] pub fn reveal(self) -> traits::Reveal { self.packed.tag() } /// Construct a trait environment with no where-clauses in scope /// where the values of all `impl Trait` and other hidden types /// are revealed. This is suitable for monomorphized, post-typeck /// environments like codegen or doing optimizations. /// /// N.B., if you want to have predicates in scope, use `ParamEnv::new`, /// or invoke `param_env.with_reveal_all()`. #[inline] pub fn reveal_all() -> Self { Self::new(List::empty(), Reveal::All) } /// Construct a trait environment with the given set of predicates. #[inline] pub fn new(caller_bounds: &'tcx List>, reveal: Reveal) -> Self { ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, reveal) } } pub fn with_user_facing(mut self) -> Self { self.packed.set_tag(Reveal::UserFacing); self } /// Returns a new parameter environment with the same clauses, but /// which "reveals" the true results of projections in all cases /// (even for associated types that are specializable). This is /// the desired behavior during codegen and certain other special /// contexts; normally though we want to use `Reveal::UserFacing`, /// which is the default. /// All opaque types in the caller_bounds of the `ParamEnv` /// will be normalized to their underlying types. /// See PR #65989 and issue #65918 for more details pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self { if self.packed.tag() == traits::Reveal::All { return self; } ParamEnv::new(tcx.normalize_opaque_types(self.caller_bounds()), Reveal::All) } /// Returns this same environment but with no caller bounds. #[inline] pub fn without_caller_bounds(self) -> Self { Self::new(List::empty(), self.reveal()) } /// Creates a suitable environment in which to perform trait /// queries on the given value. When type-checking, this is simply /// the pair of the environment plus value. But when reveal is set to /// All, then if `value` does not reference any type parameters, we will /// pair it with the empty environment. This improves caching and is generally /// invisible. /// /// N.B., we preserve the environment when type-checking because it /// is possible for the user to have wacky where-clauses like /// `where Box: Copy`, which are clearly never /// satisfiable. We generally want to behave as if they were true, /// although the surrounding function is never reachable. pub fn and>(self, value: T) -> ParamEnvAnd<'tcx, T> { match self.reveal() { Reveal::UserFacing => ParamEnvAnd { param_env: self, value }, Reveal::All => { if value.is_known_global() { ParamEnvAnd { param_env: self.without_caller_bounds(), value } } else { ParamEnvAnd { param_env: self, value } } } } } } #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)] pub struct ConstnessAnd { pub constness: BoundConstness, pub value: T, } // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that // the constness of trait bounds is being propagated correctly. pub trait WithConstness: Sized { #[inline] fn with_constness(self, constness: BoundConstness) -> ConstnessAnd { ConstnessAnd { constness, value: self } } #[inline] fn with_const_if_const(self) -> ConstnessAnd { self.with_constness(BoundConstness::ConstIfConst) } #[inline] fn without_const(self) -> ConstnessAnd { self.with_constness(BoundConstness::NotConst) } } impl WithConstness for T {} #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)] pub struct ParamEnvAnd<'tcx, T> { pub param_env: ParamEnv<'tcx>, pub value: T, } impl<'tcx, T> ParamEnvAnd<'tcx, T> { pub fn into_parts(self) -> (ParamEnv<'tcx>, T) { (self.param_env, self.value) } } impl<'a, 'tcx, T> HashStable> for ParamEnvAnd<'tcx, T> where T: HashStable>, { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { let ParamEnvAnd { ref param_env, ref value } = *self; param_env.hash_stable(hcx, hasher); value.hash_stable(hcx, hasher); } } #[derive(Copy, Clone, Debug, HashStable)] pub struct Destructor { /// The `DefId` of the destructor method pub did: DefId, /// The constness of the destructor method pub constness: hir::Constness, } bitflags! { #[derive(HashStable)] pub struct VariantFlags: u32 { const NO_VARIANT_FLAGS = 0; /// Indicates whether the field list of this variant is `#[non_exhaustive]`. const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0; /// Indicates whether this variant was obtained as part of recovering from /// a syntactic error. May be incomplete or bogus. const IS_RECOVERED = 1 << 1; } } /// Definition of a variant -- a struct's fields or an enum variant. #[derive(Debug, HashStable)] pub struct VariantDef { /// `DefId` that identifies the variant itself. /// If this variant belongs to a struct or union, then this is a copy of its `DefId`. pub def_id: DefId, /// `DefId` that identifies the variant's constructor. /// If this variant is a struct variant, then this is `None`. pub ctor_def_id: Option, /// Variant or struct name. #[stable_hasher(project(name))] pub ident: Ident, /// Discriminant of this variant. pub discr: VariantDiscr, /// Fields of this variant. pub fields: Vec, /// Type of constructor of variant. pub ctor_kind: CtorKind, /// Flags of the variant (e.g. is field list non-exhaustive)? flags: VariantFlags, } impl VariantDef { /// Creates a new `VariantDef`. /// /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef` /// represents an enum variant). /// /// `ctor_did` is the `DefId` that identifies the constructor of unit or /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`. /// /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having /// to go through the redirect of checking the ctor's attributes - but compiling a small crate /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any /// built-in trait), and we do not want to load attributes twice. /// /// If someone speeds up attribute loading to not be a performance concern, they can /// remove this hack and use the constructor `DefId` everywhere. pub fn new( ident: Ident, variant_did: Option, ctor_def_id: Option, discr: VariantDiscr, fields: Vec, ctor_kind: CtorKind, adt_kind: AdtKind, parent_did: DefId, recovered: bool, is_field_list_non_exhaustive: bool, ) -> Self { debug!( "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?}, fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})", ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did, ); let mut flags = VariantFlags::NO_VARIANT_FLAGS; if is_field_list_non_exhaustive { flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE; } if recovered { flags |= VariantFlags::IS_RECOVERED; } VariantDef { def_id: variant_did.unwrap_or(parent_did), ctor_def_id, ident, discr, fields, ctor_kind, flags, } } /// Is this field list non-exhaustive? #[inline] pub fn is_field_list_non_exhaustive(&self) -> bool { self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE) } /// Was this variant obtained as part of recovering from a syntactic error? #[inline] pub fn is_recovered(&self) -> bool { self.flags.intersects(VariantFlags::IS_RECOVERED) } } #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)] pub enum VariantDiscr { /// Explicit value for this variant, i.e., `X = 123`. /// The `DefId` corresponds to the embedded constant. Explicit(DefId), /// The previous variant's discriminant plus one. /// For efficiency reasons, the distance from the /// last `Explicit` discriminant is being stored, /// or `0` for the first variant, if it has none. Relative(u32), } #[derive(Debug, HashStable)] pub struct FieldDef { pub did: DefId, #[stable_hasher(project(name))] pub ident: Ident, pub vis: Visibility, } bitflags! { #[derive(TyEncodable, TyDecodable, Default, HashStable)] pub struct ReprFlags: u8 { const IS_C = 1 << 0; const IS_SIMD = 1 << 1; const IS_TRANSPARENT = 1 << 2; // Internal only for now. If true, don't reorder fields. const IS_LINEAR = 1 << 3; // If true, don't expose any niche to type's context. const HIDE_NICHE = 1 << 4; // If true, the type's layout can be randomized using // the seed stored in `ReprOptions.layout_seed` const RANDOMIZE_LAYOUT = 1 << 5; // Any of these flags being set prevent field reordering optimisation. const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits | ReprFlags::IS_SIMD.bits | ReprFlags::IS_LINEAR.bits; } } /// Represents the repr options provided by the user, #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)] pub struct ReprOptions { pub int: Option, pub align: Option, pub pack: Option, pub flags: ReprFlags, /// The seed to be used for randomizing a type's layout /// /// Note: This could technically be a `[u8; 16]` (a `u128`) which would /// be the "most accurate" hash as it'd encompass the item and crate /// hash without loss, but it does pay the price of being larger. /// Everything's a tradeoff, a `u64` seed should be sufficient for our /// purposes (primarily `-Z randomize-layout`) pub field_shuffle_seed: u64, } impl ReprOptions { pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions { let mut flags = ReprFlags::empty(); let mut size = None; let mut max_align: Option = None; let mut min_pack: Option = None; // Generate a deterministically-derived seed from the item's path hash // to allow for cross-crate compilation to actually work let field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash(); for attr in tcx.get_attrs(did).iter() { for r in attr::find_repr_attrs(&tcx.sess, attr) { flags.insert(match r { attr::ReprC => ReprFlags::IS_C, attr::ReprPacked(pack) => { let pack = Align::from_bytes(pack as u64).unwrap(); min_pack = Some(if let Some(min_pack) = min_pack { min_pack.min(pack) } else { pack }); ReprFlags::empty() } attr::ReprTransparent => ReprFlags::IS_TRANSPARENT, attr::ReprNoNiche => ReprFlags::HIDE_NICHE, attr::ReprSimd => ReprFlags::IS_SIMD, attr::ReprInt(i) => { size = Some(i); ReprFlags::empty() } attr::ReprAlign(align) => { max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap())); ReprFlags::empty() } }); } } // If `-Z randomize-layout` was enabled for the type definition then we can // consider performing layout randomization if tcx.sess.opts.debugging_opts.randomize_layout { flags.insert(ReprFlags::RANDOMIZE_LAYOUT); } // This is here instead of layout because the choice must make it into metadata. if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) { flags.insert(ReprFlags::IS_LINEAR); } Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed } } #[inline] pub fn simd(&self) -> bool { self.flags.contains(ReprFlags::IS_SIMD) } #[inline] pub fn c(&self) -> bool { self.flags.contains(ReprFlags::IS_C) } #[inline] pub fn packed(&self) -> bool { self.pack.is_some() } #[inline] pub fn transparent(&self) -> bool { self.flags.contains(ReprFlags::IS_TRANSPARENT) } #[inline] pub fn linear(&self) -> bool { self.flags.contains(ReprFlags::IS_LINEAR) } #[inline] pub fn hide_niche(&self) -> bool { self.flags.contains(ReprFlags::HIDE_NICHE) } /// Returns the discriminant type, given these `repr` options. /// This must only be called on enums! pub fn discr_type(&self) -> attr::IntType { self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize)) } /// Returns `true` if this `#[repr()]` should inhabit "smart enum /// layout" optimizations, such as representing `Foo<&T>` as a /// single pointer. pub fn inhibit_enum_layout_opt(&self) -> bool { self.c() || self.int.is_some() } /// Returns `true` if this `#[repr()]` should inhibit struct field reordering /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr()`. pub fn inhibit_struct_field_reordering_opt(&self) -> bool { if let Some(pack) = self.pack { if pack.bytes() == 1 { return true; } } self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some() } /// Returns `true` if this type is valid for reordering and `-Z randomize-layout` /// was enabled for its declaration crate pub fn can_randomize_type_layout(&self) -> bool { !self.inhibit_struct_field_reordering_opt() && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT) } /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations. pub fn inhibit_union_abi_opt(&self) -> bool { self.c() } } impl<'tcx> FieldDef { /// Returns the type of this field. The resulting type is not normalized. The `subst` is /// typically obtained via the second field of `TyKind::AdtDef`. pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> { tcx.type_of(self.did).subst(tcx, subst) } } pub type Attributes<'tcx> = &'tcx [ast::Attribute]; #[derive(Debug, PartialEq, Eq)] pub enum ImplOverlapKind { /// These impls are always allowed to overlap. Permitted { /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait marker: bool, }, /// These impls are allowed to overlap, but that raises /// an issue #33140 future-compatibility warning. /// /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different. /// /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied /// that difference, making what reduces to the following set of impls: /// /// ``` /// trait Trait {} /// impl Trait for dyn Send + Sync {} /// impl Trait for dyn Sync + Send {} /// ``` /// /// Obviously, once we made these types be identical, that code causes a coherence /// error and a fairly big headache for us. However, luckily for us, the trait /// `Trait` used in this case is basically a marker trait, and therefore having /// overlapping impls for it is sound. /// /// To handle this, we basically regard the trait as a marker trait, with an additional /// future-compatibility warning. To avoid accidentally "stabilizing" this feature, /// it has the following restrictions: /// /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be /// positive impls. /// 2. The trait-ref of both impls must be equal. /// 3. The trait-ref of both impls must be a trait object type consisting only of /// marker traits. /// 4. Neither of the impls can have any where-clauses. /// /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed. Issue33140, } impl<'tcx> TyCtxt<'tcx> { pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> { self.typeck(self.hir().body_owner_def_id(body)) } pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator { self.associated_items(id) .in_definition_order() .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value()) } fn item_name_from_hir(self, def_id: DefId) -> Option { self.hir().get_if_local(def_id).and_then(|node| node.ident()) } fn item_name_from_def_id(self, def_id: DefId) -> Option { if def_id.index == CRATE_DEF_INDEX { Some(self.crate_name(def_id.krate)) } else { let def_key = self.def_key(def_id); match def_key.disambiguated_data.data { // The name of a constructor is that of its parent. rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId { krate: def_id.krate, index: def_key.parent.unwrap(), }), _ => def_key.disambiguated_data.data.get_opt_name(), } } } /// Look up the name of an item across crates. This does not look at HIR. /// /// When possible, this function should be used for cross-crate lookups over /// [`opt_item_name`] to avoid invalidating the incremental cache. If you /// need to handle items without a name, or HIR items that will not be /// serialized cross-crate, or if you need the span of the item, use /// [`opt_item_name`] instead. /// /// [`opt_item_name`]: Self::opt_item_name pub fn item_name(self, id: DefId) -> Symbol { // Look at cross-crate items first to avoid invalidating the incremental cache // unless we have to. self.item_name_from_def_id(id).unwrap_or_else(|| { bug!("item_name: no name for {:?}", self.def_path(id)); }) } /// Look up the name and span of an item or [`Node`]. /// /// See [`item_name`][Self::item_name] for more information. pub fn opt_item_name(self, def_id: DefId) -> Option { // Look at the HIR first so the span will be correct if this is a local item. self.item_name_from_hir(def_id) .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span)) } pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> { if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) { Some(self.associated_item(def_id)) } else { None } } pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize { typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field") } pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option { variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id)) } /// Returns `true` if the impls are the same polarity and the trait either /// has no items or is annotated `#[marker]` and prevents item overrides. pub fn impls_are_allowed_to_overlap( self, def_id1: DefId, def_id2: DefId, ) -> Option { // If either trait impl references an error, they're allowed to overlap, // as one of them essentially doesn't exist. if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error()) || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error()) { return Some(ImplOverlapKind::Permitted { marker: false }); } match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) { (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => { // `#[rustc_reservation_impl]` impls don't overlap with anything debug!( "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)", def_id1, def_id2 ); return Some(ImplOverlapKind::Permitted { marker: false }); } (ImplPolarity::Positive, ImplPolarity::Negative) | (ImplPolarity::Negative, ImplPolarity::Positive) => { // `impl AutoTrait for Type` + `impl !AutoTrait for Type` debug!( "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)", def_id1, def_id2 ); return None; } (ImplPolarity::Positive, ImplPolarity::Positive) | (ImplPolarity::Negative, ImplPolarity::Negative) => {} }; let is_marker_overlap = { let is_marker_impl = |def_id: DefId| -> bool { let trait_ref = self.impl_trait_ref(def_id); trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker) }; is_marker_impl(def_id1) && is_marker_impl(def_id2) }; if is_marker_overlap { debug!( "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)", def_id1, def_id2 ); Some(ImplOverlapKind::Permitted { marker: true }) } else { if let Some(self_ty1) = self.issue33140_self_ty(def_id1) { if let Some(self_ty2) = self.issue33140_self_ty(def_id2) { if self_ty1 == self_ty2 { debug!( "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK", def_id1, def_id2 ); return Some(ImplOverlapKind::Issue33140); } else { debug!( "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}", def_id1, def_id2, self_ty1, self_ty2 ); } } } debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2); None } } /// Returns `ty::VariantDef` if `res` refers to a struct, /// or variant or their constructors, panics otherwise. pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef { match res { Res::Def(DefKind::Variant, did) => { let enum_did = self.parent(did).unwrap(); self.adt_def(enum_did).variant_with_id(did) } Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(), Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => { let variant_did = self.parent(variant_ctor_did).unwrap(); let enum_did = self.parent(variant_did).unwrap(); self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did) } Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => { let struct_did = self.parent(ctor_did).expect("struct ctor has no parent"); self.adt_def(struct_did).non_enum_variant() } _ => bug!("expect_variant_res used with unexpected res {:?}", res), } } /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair. pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> { match instance { ty::InstanceDef::Item(def) => match self.def_kind(def.did) { DefKind::Const | DefKind::Static | DefKind::AssocConst | DefKind::Ctor(..) | DefKind::AnonConst => self.mir_for_ctfe_opt_const_arg(def), // If the caller wants `mir_for_ctfe` of a function they should not be using // `instance_mir`, so we'll assume const fn also wants the optimized version. _ => { assert_eq!(def.const_param_did, None); self.optimized_mir(def.did) } }, ty::InstanceDef::VtableShim(..) | ty::InstanceDef::ReifyShim(..) | ty::InstanceDef::Intrinsic(..) | ty::InstanceDef::FnPtrShim(..) | ty::InstanceDef::Virtual(..) | ty::InstanceDef::ClosureOnceShim { .. } | ty::InstanceDef::DropGlue(..) | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance), } } /// Gets the attributes of a definition. pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> { if let Some(did) = did.as_local() { self.hir().attrs(self.hir().local_def_id_to_hir_id(did)) } else { self.item_attrs(did) } } /// Determines whether an item is annotated with an attribute. pub fn has_attr(self, did: DefId, attr: Symbol) -> bool { self.sess.contains_name(&self.get_attrs(did), attr) } /// Returns `true` if this is an `auto trait`. pub fn trait_is_auto(self, trait_def_id: DefId) -> bool { self.trait_def(trait_def_id).has_auto_impl } /// Returns layout of a generator. Layout might be unavailable if the /// generator is tainted by errors. pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> { self.optimized_mir(def_id).generator_layout() } /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements. /// If it implements no trait, returns `None`. pub fn trait_id_of_impl(self, def_id: DefId) -> Option { self.impl_trait_ref(def_id).map(|tr| tr.def_id) } /// If the given defid describes a method belonging to an impl, returns the /// `DefId` of the impl that the method belongs to; otherwise, returns `None`. pub fn impl_of_method(self, def_id: DefId) -> Option { self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container { TraitContainer(_) => None, ImplContainer(def_id) => Some(def_id), }) } /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err` /// with the name of the crate containing the impl. pub fn span_of_impl(self, impl_did: DefId) -> Result { if let Some(impl_did) = impl_did.as_local() { let hir_id = self.hir().local_def_id_to_hir_id(impl_did); Ok(self.hir().span(hir_id)) } else { Err(self.crate_name(impl_did.krate)) } } /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed /// definition's parent/scope to perform comparison. pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool { // We could use `Ident::eq` here, but we deliberately don't. The name // comparison fails frequently, and we want to avoid the expensive // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible. use_name.name == def_name.name && use_name .span .ctxt() .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id)) } pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident { ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope)); ident } pub fn adjust_ident_and_get_scope( self, mut ident: Ident, scope: DefId, block: hir::HirId, ) -> (Ident, DefId) { let scope = ident .span .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope)) .and_then(|actual_expansion| actual_expansion.expn_data().parent_module) .unwrap_or_else(|| self.parent_module(block).to_def_id()); (ident, scope) } pub fn is_object_safe(self, key: DefId) -> bool { self.object_safety_violations(key).is_empty() } } /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition. pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option { if let Some(def_id) = def_id.as_local() { if let Node::Item(item) = tcx.hir().get(tcx.hir().local_def_id_to_hir_id(def_id)) { if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind { return opaque_ty.impl_trait_fn; } } } None } pub fn int_ty(ity: ast::IntTy) -> IntTy { match ity { ast::IntTy::Isize => IntTy::Isize, ast::IntTy::I8 => IntTy::I8, ast::IntTy::I16 => IntTy::I16, ast::IntTy::I32 => IntTy::I32, ast::IntTy::I64 => IntTy::I64, ast::IntTy::I128 => IntTy::I128, } } pub fn uint_ty(uty: ast::UintTy) -> UintTy { match uty { ast::UintTy::Usize => UintTy::Usize, ast::UintTy::U8 => UintTy::U8, ast::UintTy::U16 => UintTy::U16, ast::UintTy::U32 => UintTy::U32, ast::UintTy::U64 => UintTy::U64, ast::UintTy::U128 => UintTy::U128, } } pub fn float_ty(fty: ast::FloatTy) -> FloatTy { match fty { ast::FloatTy::F32 => FloatTy::F32, ast::FloatTy::F64 => FloatTy::F64, } } pub fn ast_int_ty(ity: IntTy) -> ast::IntTy { match ity { IntTy::Isize => ast::IntTy::Isize, IntTy::I8 => ast::IntTy::I8, IntTy::I16 => ast::IntTy::I16, IntTy::I32 => ast::IntTy::I32, IntTy::I64 => ast::IntTy::I64, IntTy::I128 => ast::IntTy::I128, } } pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy { match uty { UintTy::Usize => ast::UintTy::Usize, UintTy::U8 => ast::UintTy::U8, UintTy::U16 => ast::UintTy::U16, UintTy::U32 => ast::UintTy::U32, UintTy::U64 => ast::UintTy::U64, UintTy::U128 => ast::UintTy::U128, } } pub fn provide(providers: &mut ty::query::Providers) { closure::provide(providers); context::provide(providers); erase_regions::provide(providers); layout::provide(providers); util::provide(providers); print::provide(providers); super::util::bug::provide(providers); super::middle::provide(providers); *providers = ty::query::Providers { trait_impls_of: trait_def::trait_impls_of_provider, type_uninhabited_from: inhabitedness::type_uninhabited_from, const_param_default: consts::const_param_default, ..*providers }; } /// A map for the local crate mapping each type to a vector of its /// inherent impls. This is not meant to be used outside of coherence; /// rather, you should request the vector for a specific type via /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies /// (constructing this map requires touching the entire crate). #[derive(Clone, Debug, Default, HashStable)] pub struct CrateInherentImpls { pub inherent_impls: LocalDefIdMap>, } #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)] pub struct SymbolName<'tcx> { /// `&str` gives a consistent ordering, which ensures reproducible builds. pub name: &'tcx str, } impl<'tcx> SymbolName<'tcx> { pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> { SymbolName { name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) }, } } } impl<'tcx> fmt::Display for SymbolName<'tcx> { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Display::fmt(&self.name, fmt) } } impl<'tcx> fmt::Debug for SymbolName<'tcx> { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Display::fmt(&self.name, fmt) } } #[derive(Debug, Default, Copy, Clone)] pub struct FoundRelationships { /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo` /// obligation, where: /// /// * `Foo` is not `Sized` /// * `(): Foo` may be satisfied pub self_in_trait: bool, /// This is true if we identified that this Ty (`?T`) is found in a `<_ as /// _>::AssocType = ?T` pub output: bool, }