//! 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 rustc-dev-guide. //! //! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html #![allow(rustc::usage_of_ty_tykind)] pub use self::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeSuperFoldable}; pub use self::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor}; pub use self::AssocItemContainer::*; pub use self::BorrowKind::*; pub use self::IntVarValue::*; pub use self::Variance::*; use crate::error::{OpaqueHiddenTypeMismatch, TypeMismatchReason}; use crate::metadata::ModChild; use crate::middle::privacy::EffectiveVisibilities; use crate::mir::{Body, GeneratorLayout}; use crate::traits::{self, Reveal}; use crate::ty; use crate::ty::fast_reject::SimplifiedType; use crate::ty::util::Discr; pub use adt::*; pub use assoc::*; pub use generics::*; use rustc_ast as ast; use rustc_ast::node_id::NodeMap; use rustc_attr as attr; use rustc_data_structures::fingerprint::Fingerprint; use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet}; use rustc_data_structures::intern::Interned; 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, LifetimeRes, Res}; use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LocalDefIdMap}; use rustc_hir::Node; use rustc_index::vec::IndexVec; use rustc_macros::HashStable; use rustc_query_system::ich::StableHashingContext; use rustc_serialize::{Decodable, Encodable}; use rustc_session::cstore::Untracked; use rustc_span::hygiene::MacroKind; use rustc_span::symbol::{kw, sym, Ident, Symbol}; use rustc_span::{ExpnId, Span}; use rustc_target::abi::{Align, Integer, IntegerType, VariantIdx}; pub use rustc_target::abi::{ReprFlags, ReprOptions}; use rustc_type_ir::WithCachedTypeInfo; pub use subst::*; pub use vtable::*; use std::fmt::Debug; use std::hash::{Hash, Hasher}; use std::marker::PhantomData; use std::mem; use std::num::NonZeroUsize; use std::ops::ControlFlow; use std::{fmt, str}; pub use crate::ty::diagnostics::*; pub use rustc_type_ir::AliasKind::*; pub use rustc_type_ir::DynKind::*; pub use rustc_type_ir::InferTy::*; pub use rustc_type_ir::RegionKind::*; pub use rustc_type_ir::TyKind::*; 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, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath, CAPTURE_STRUCT_LOCAL, }; pub use self::consts::{ Const, ConstData, ConstInt, ConstKind, Expr, InferConst, ScalarInt, UnevaluatedConst, ValTree, }; pub use self::context::{ tls, CtxtInterners, DeducedParamAttrs, FreeRegionInfo, GlobalCtxt, Lift, OnDiskCache, TyCtxt, TyCtxtFeed, }; pub use self::instance::{Instance, InstanceDef, ShortInstance, UnusedGenericParams}; pub use self::list::List; pub use self::parameterized::ParameterizedOverTcx; pub use self::rvalue_scopes::RvalueScopes; pub use self::sty::BoundRegionKind::*; pub use self::sty::{ AliasTy, Article, Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind, CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBoundRegion, ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig, GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts, InlineConstSubstsParts, ParamConst, ParamTy, PolyExistentialPredicate, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig, PolyTraitRef, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut, UpvarSubsts, VarianceDiagInfo, }; pub use self::trait_def::TraitDef; pub use self::typeck_results::{ CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, GeneratorDiagnosticData, GeneratorInteriorTypeCause, TypeckResults, UserType, UserTypeAnnotationIndex, }; pub mod _match; pub mod abstract_const; 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 print; pub mod query; pub mod relate; pub mod subst; pub mod trait_def; pub mod util; pub mod visit; pub mod vtable; pub mod walk; mod adt; mod assoc; mod closure; mod consts; mod context; mod diagnostics; mod erase_regions; mod generics; mod impls_ty; mod instance; mod list; mod opaque_types; mod parameterized; mod rvalue_scopes; mod structural_impls; mod sty; mod typeck_results; // Data types pub type RegisteredTools = FxHashSet; pub struct ResolverOutputs { pub global_ctxt: ResolverGlobalCtxt, pub ast_lowering: ResolverAstLowering, pub untracked: Untracked, } #[derive(Debug)] pub struct ResolverGlobalCtxt { pub visibilities: FxHashMap, /// This field is used to decide whether we should make `PRIVATE_IN_PUBLIC` a hard error. pub has_pub_restricted: bool, /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`. pub expn_that_defined: FxHashMap, pub effective_visibilities: EffectiveVisibilities, pub extern_crate_map: FxHashMap, pub maybe_unused_trait_imports: FxIndexSet, pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>, pub reexport_map: FxHashMap>, 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: FxIndexMap>, /// 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, pub registered_tools: RegisteredTools, } /// Resolutions that should only be used for lowering. /// This struct is meant to be consumed by lowering. #[derive(Debug)] pub struct ResolverAstLowering { pub legacy_const_generic_args: FxHashMap>>, /// Resolutions for nodes that have a single resolution. pub partial_res_map: NodeMap, /// Resolutions for import nodes, which have multiple resolutions in different namespaces. pub import_res_map: NodeMap>>>, /// Resolutions for labels (node IDs of their corresponding blocks or loops). pub label_res_map: NodeMap, /// Resolutions for lifetimes. pub lifetimes_res_map: NodeMap, /// Lifetime parameters that lowering will have to introduce. pub extra_lifetime_params_map: NodeMap>, pub next_node_id: ast::NodeId, pub node_id_to_def_id: FxHashMap, pub def_id_to_node_id: IndexVec, pub trait_map: NodeMap>, /// A small map keeping true kinds of built-in macros that appear to be fn-like on /// the surface (`macro` items in libcore), but are actually attributes or derives. pub builtin_macro_kinds: FxHashMap, /// List functions and methods for which lifetime elision was successful. pub lifetime_elision_allowed: FxHashSet, } #[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, TypeVisitable)] 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, Eq, Debug, TypeFoldable, TypeVisitable)] pub enum ImplSubject<'tcx> { Trait(TraitRef<'tcx>), Inherent(Ty<'tcx>), } #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable, Debug)] #[derive(TypeFoldable, TypeVisitable)] 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, } impl ImplPolarity { /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`. pub fn flip(&self) -> Option { match self { ImplPolarity::Positive => Some(ImplPolarity::Negative), ImplPolarity::Negative => Some(ImplPolarity::Positive), ImplPolarity::Reservation => None, } } } impl fmt::Display for ImplPolarity { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { match self { Self::Positive => f.write_str("positive"), Self::Negative => f.write_str("negative"), Self::Reservation => f.write_str("reservation"), } } } #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, Encodable, Decodable, HashStable)] pub enum Visibility { /// Visible everywhere (including in other crates). Public, /// Visible only in the given crate-local module. Restricted(Id), } #[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 BoundConstness { /// Reduce `self` and `constness` to two possible combined states instead of four. pub fn and(&mut self, constness: hir::Constness) -> hir::Constness { match (constness, self) { (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const, (_, this) => { *this = BoundConstness::NotConst; hir::Constness::NotConst } } } } 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)] #[derive(TypeFoldable, TypeVisitable)] 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 opt_parent(self, id: DefId) -> Option; #[inline] #[track_caller] fn parent(self, id: DefId) -> DefId { match self.opt_parent(id) { Some(id) => id, // not `unwrap_or_else` to avoid breaking caller tracking None => bug!("{id:?} doesn't have a parent"), } } #[inline] #[track_caller] fn opt_local_parent(self, id: LocalDefId) -> Option { self.opt_parent(id.to_def_id()).map(DefId::expect_local) } #[inline] #[track_caller] fn local_parent(self, id: LocalDefId) -> LocalDefId { self.parent(id.to_def_id()).expect_local() } fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool { if descendant.krate != ancestor.krate { return false; } while descendant != ancestor { match self.opt_parent(descendant) { Some(parent) => descendant = parent, None => return false, } } true } } impl<'tcx> DefIdTree for TyCtxt<'tcx> { #[inline] fn opt_parent(self, id: DefId) -> Option { self.def_key(id).parent.map(|index| DefId { index, ..id }) } } impl Visibility { pub fn is_public(self) -> bool { matches!(self, Visibility::Public) } pub fn map_id(self, f: impl FnOnce(Id) -> OutId) -> Visibility { match self { Visibility::Public => Visibility::Public, Visibility::Restricted(id) => Visibility::Restricted(f(id)), } } } impl> Visibility { pub fn to_def_id(self) -> Visibility { self.map_id(Into::into) } /// Returns `true` if an item with this visibility is accessible from the given module. pub fn is_accessible_from(self, module: impl Into, tree: impl DefIdTree) -> bool { match self { // Public items are visible everywhere. Visibility::Public => true, Visibility::Restricted(id) => tree.is_descendant_of(module.into(), id.into()), } } /// Returns `true` if this visibility is at least as accessible as the given visibility pub fn is_at_least(self, vis: Visibility>, tree: impl DefIdTree) -> bool { match vis { Visibility::Public => self.is_public(), Visibility::Restricted(id) => self.is_accessible_from(id, tree), } } } impl Visibility { pub fn expect_local(self) -> Visibility { self.map_id(|id| id.expect_local()) } /// 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(), } } } /// 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: DefIdMap<&'tcx [ty::Variance]>, } // 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, } /// Use this rather than `TyKind`, whenever possible. #[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)] #[rustc_diagnostic_item = "Ty"] #[rustc_pass_by_value] pub struct Ty<'tcx>(Interned<'tcx, WithCachedTypeInfo>>); impl<'tcx> TyCtxt<'tcx> { /// A "bool" type used in rustc_mir_transform unit tests when we /// have not spun up a TyCtxt. pub const BOOL_TY_FOR_UNIT_TESTING: Ty<'tcx> = Ty(Interned::new_unchecked(&WithCachedTypeInfo { internee: ty::Bool, stable_hash: Fingerprint::ZERO, flags: TypeFlags::empty(), outer_exclusive_binder: DebruijnIndex::from_usize(0), })); } 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 && self.name != kw::Empty } } /// Use this rather than `PredicateKind`, whenever possible. #[derive(Clone, Copy, PartialEq, Eq, Hash, HashStable)] #[rustc_pass_by_value] pub struct Predicate<'tcx>( Interned<'tcx, WithCachedTypeInfo>>>, ); impl<'tcx> Predicate<'tcx> { /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`. #[inline] pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> { self.0.internee } #[inline(always)] pub fn flags(self) -> TypeFlags { self.0.flags } #[inline(always)] pub fn outer_exclusive_binder(self) -> DebruijnIndex { self.0.outer_exclusive_binder } /// Flips the polarity of a Predicate. /// /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`. pub fn flip_polarity(self, tcx: TyCtxt<'tcx>) -> Option> { let kind = self .kind() .map_bound(|kind| match kind { PredicateKind::Clause(Clause::Trait(TraitPredicate { trait_ref, constness, polarity, })) => Some(PredicateKind::Clause(Clause::Trait(TraitPredicate { trait_ref, constness, polarity: polarity.flip()?, }))), _ => None, }) .transpose()?; Some(tcx.mk_predicate(kind)) } pub fn without_const(mut self, tcx: TyCtxt<'tcx>) -> Self { if let PredicateKind::Clause(Clause::Trait(TraitPredicate { trait_ref, constness, polarity })) = self.kind().skip_binder() && constness != BoundConstness::NotConst { self = tcx.mk_predicate(self.kind().rebind(PredicateKind::Clause(Clause::Trait(TraitPredicate { trait_ref, constness: BoundConstness::NotConst, polarity, })))); } self } #[instrument(level = "debug", skip(tcx), ret)] pub fn is_coinductive(self, tcx: TyCtxt<'tcx>) -> bool { match self.kind().skip_binder() { ty::PredicateKind::Clause(ty::Clause::Trait(data)) => { tcx.trait_is_coinductive(data.def_id()) } ty::PredicateKind::WellFormed(_) => true, _ => false, } } /// Whether this projection can be soundly normalized. /// /// Wf predicates must not be normalized, as normalization /// can remove required bounds which would cause us to /// unsoundly accept some programs. See #91068. #[inline] pub fn allow_normalization(self) -> bool { match self.kind().skip_binder() { PredicateKind::WellFormed(_) => false, PredicateKind::Clause(Clause::Trait(_)) | PredicateKind::Clause(Clause::RegionOutlives(_)) | PredicateKind::Clause(Clause::TypeOutlives(_)) | PredicateKind::Clause(Clause::Projection(_)) | PredicateKind::ObjectSafe(_) | PredicateKind::ClosureKind(_, _, _) | PredicateKind::Subtype(_) | PredicateKind::Coerce(_) | PredicateKind::ConstEvaluatable(_) | PredicateKind::ConstEquate(_, _) | PredicateKind::Ambiguous | PredicateKind::TypeWellFormedFromEnv(_) => true, } } } impl rustc_errors::IntoDiagnosticArg for Predicate<'_> { fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> { rustc_errors::DiagnosticArgValue::Str(std::borrow::Cow::Owned(self.to_string())) } } #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] /// A clause is something that can appear in where bounds or be inferred /// by implied bounds. pub enum Clause<'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>), } #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] pub enum PredicateKind<'tcx> { /// Prove a clause Clause(Clause<'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::Const<'tcx>), /// Constants must be equal. The first component is the const that is expected. ConstEquate(Const<'tcx>, Const<'tcx>), /// Represents a type found in the environment that we can use for implied bounds. /// /// Only used for Chalk. TypeWellFormedFromEnv(Ty<'tcx>), /// A marker predicate that is always ambiguous. /// Used for coherence to mark opaque types as possibly equal to each other but ambiguous. Ambiguous, } /// 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 = EarlyBinder(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, TypeVisitable, Lift)] pub struct TraitPredicate<'tcx> { pub trait_ref: TraitRef<'tcx>, pub constness: BoundConstness, /// If polarity is Positive: we are proving that the trait is implemented. /// /// If polarity is Negative: we are proving that a negative impl of this trait /// exists. (Note that coherence also checks whether negative impls of supertraits /// exist via a series of predicates.) /// /// If polarity is Reserved: that's a bug. pub polarity: ImplPolarity, } pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>; impl<'tcx> TraitPredicate<'tcx> { pub fn remap_constness(&mut self, param_env: &mut ParamEnv<'tcx>) { *param_env = param_env.with_constness(self.constness.and(param_env.constness())) } /// Remap the constness of this predicate before emitting it for diagnostics. pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) { // this is different to `remap_constness` that callees want to print this predicate // in case of selection errors. `T: ~const Drop` bounds cannot end up here when the // param_env is not const because it is always satisfied in non-const contexts. if let hir::Constness::NotConst = param_env.constness() { self.constness = ty::BoundConstness::NotConst; } } pub fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> Self { Self { trait_ref: self.trait_ref.with_self_ty(tcx, self_ty), ..self } } pub fn def_id(self) -> DefId { self.trait_ref.def_id } pub fn self_ty(self) -> Ty<'tcx> { self.trait_ref.self_ty() } #[inline] pub fn is_const_if_const(self) -> bool { self.constness == BoundConstness::ConstIfConst } pub fn is_constness_satisfied_by(self, constness: hir::Constness) -> bool { match (self.constness, constness) { (BoundConstness::NotConst, _) | (BoundConstness::ConstIfConst, hir::Constness::Const) => true, (BoundConstness::ConstIfConst, hir::Constness::NotConst) => false, } } pub fn without_const(mut self) -> Self { self.constness = BoundConstness::NotConst; self } } 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()) } /// Remap the constness of this predicate before emitting it for diagnostics. pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) { *self = self.map_bound(|mut p| { p.remap_constness_diag(param_env); p }); } #[inline] pub fn is_const_if_const(self) -> bool { self.skip_binder().is_const_if_const() } } /// `A: B` #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable, Lift)] pub struct OutlivesPredicate(pub A, pub 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, TypeVisitable, Lift)] 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, TypeVisitable, Lift)] pub struct CoercePredicate<'tcx> { pub a: Ty<'tcx>, pub b: Ty<'tcx>, } pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>; #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] pub struct Term<'tcx> { ptr: NonZeroUsize, marker: PhantomData<(Ty<'tcx>, Const<'tcx>)>, } impl Debug for Term<'_> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { let data = if let Some(ty) = self.ty() { format!("Term::Ty({:?})", ty) } else if let Some(ct) = self.ct() { format!("Term::Ct({:?})", ct) } else { unreachable!() }; f.write_str(&data) } } impl<'tcx> From> for Term<'tcx> { fn from(ty: Ty<'tcx>) -> Self { TermKind::Ty(ty).pack() } } impl<'tcx> From> for Term<'tcx> { fn from(c: Const<'tcx>) -> Self { TermKind::Const(c).pack() } } impl<'a, 'tcx> HashStable> for Term<'tcx> { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { self.unpack().hash_stable(hcx, hasher); } } impl<'tcx> TypeFoldable<'tcx> for Term<'tcx> { fn try_fold_with>(self, folder: &mut F) -> Result { Ok(self.unpack().try_fold_with(folder)?.pack()) } } impl<'tcx> TypeVisitable<'tcx> for Term<'tcx> { fn visit_with>(&self, visitor: &mut V) -> ControlFlow { self.unpack().visit_with(visitor) } } impl<'tcx, E: TyEncoder>> Encodable for Term<'tcx> { fn encode(&self, e: &mut E) { self.unpack().encode(e) } } impl<'tcx, D: TyDecoder>> Decodable for Term<'tcx> { fn decode(d: &mut D) -> Self { let res: TermKind<'tcx> = Decodable::decode(d); res.pack() } } impl<'tcx> Term<'tcx> { #[inline] pub fn unpack(self) -> TermKind<'tcx> { let ptr = self.ptr.get(); // SAFETY: use of `Interned::new_unchecked` here is ok because these // pointers were originally created from `Interned` types in `pack()`, // and this is just going in the other direction. unsafe { match ptr & TAG_MASK { TYPE_TAG => TermKind::Ty(Ty(Interned::new_unchecked( &*((ptr & !TAG_MASK) as *const WithCachedTypeInfo>), ))), CONST_TAG => TermKind::Const(ty::Const(Interned::new_unchecked( &*((ptr & !TAG_MASK) as *const ty::ConstData<'tcx>), ))), _ => core::intrinsics::unreachable(), } } } pub fn ty(&self) -> Option> { if let TermKind::Ty(ty) = self.unpack() { Some(ty) } else { None } } pub fn ct(&self) -> Option> { if let TermKind::Const(c) = self.unpack() { Some(c) } else { None } } pub fn into_arg(self) -> GenericArg<'tcx> { match self.unpack() { TermKind::Ty(ty) => ty.into(), TermKind::Const(c) => c.into(), } } } const TAG_MASK: usize = 0b11; const TYPE_TAG: usize = 0b00; const CONST_TAG: usize = 0b01; #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)] #[derive(HashStable, TypeFoldable, TypeVisitable)] pub enum TermKind<'tcx> { Ty(Ty<'tcx>), Const(Const<'tcx>), } impl<'tcx> TermKind<'tcx> { #[inline] fn pack(self) -> Term<'tcx> { let (tag, ptr) = match self { TermKind::Ty(ty) => { // Ensure we can use the tag bits. assert_eq!(mem::align_of_val(&*ty.0.0) & TAG_MASK, 0); (TYPE_TAG, ty.0.0 as *const WithCachedTypeInfo> as usize) } TermKind::Const(ct) => { // Ensure we can use the tag bits. assert_eq!(mem::align_of_val(&*ct.0.0) & TAG_MASK, 0); (CONST_TAG, ct.0.0 as *const ty::ConstData<'tcx> as usize) } }; Term { ptr: unsafe { NonZeroUsize::new_unchecked(ptr | tag) }, marker: PhantomData } } } /// 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, TypeVisitable, Lift)] pub struct ProjectionPredicate<'tcx> { pub projection_ty: AliasTy<'tcx>, pub term: Term<'tcx>, } impl<'tcx> ProjectionPredicate<'tcx> { pub fn self_ty(self) -> Ty<'tcx> { self.projection_ty.self_ty() } pub fn with_self_ty(self, tcx: TyCtxt<'tcx>, self_ty: Ty<'tcx>) -> ProjectionPredicate<'tcx> { Self { projection_ty: self.projection_ty.with_self_ty(tcx, self_ty), ..self } } pub fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId { self.projection_ty.trait_def_id(tcx) } pub fn def_id(self) -> DefId { self.projection_ty.def_id } } 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 term(&self) -> Binder<'tcx, Term<'tcx>> { self.map_bound(|predicate| predicate.term) } /// 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.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, P = Predicate<'tcx>> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> P; } impl<'tcx, T> ToPredicate<'tcx, T> for T { fn to_predicate(self, _tcx: TyCtxt<'tcx>) -> T { self } } impl<'tcx> 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 Clause<'tcx> { #[inline(always)] fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { tcx.mk_predicate(ty::Binder::dummy(ty::PredicateKind::Clause(self))) } } impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, TraitRef<'tcx>> { #[inline(always)] fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { let pred: PolyTraitPredicate<'tcx> = self.to_predicate(tcx); pred.to_predicate(tcx) } } impl<'tcx> ToPredicate<'tcx, PolyTraitPredicate<'tcx>> for Binder<'tcx, TraitRef<'tcx>> { #[inline(always)] fn to_predicate(self, _: TyCtxt<'tcx>) -> PolyTraitPredicate<'tcx> { self.map_bound(|trait_ref| TraitPredicate { trait_ref, constness: ty::BoundConstness::NotConst, polarity: ty::ImplPolarity::Positive, }) } } impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { self.map_bound(|p| PredicateKind::Clause(Clause::Trait(p))).to_predicate(tcx) } } impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { self.map_bound(|p| PredicateKind::Clause(Clause::RegionOutlives(p))).to_predicate(tcx) } } impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { self.map_bound(|p| PredicateKind::Clause(Clause::TypeOutlives(p))).to_predicate(tcx) } } impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> { fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> { self.map_bound(|p| PredicateKind::Clause(Clause::Projection(p))).to_predicate(tcx) } } impl<'tcx> Predicate<'tcx> { pub fn to_opt_poly_trait_pred(self) -> Option> { let predicate = self.kind(); match predicate.skip_binder() { PredicateKind::Clause(Clause::Trait(t)) => Some(predicate.rebind(t)), PredicateKind::Clause(Clause::Projection(..)) | PredicateKind::Subtype(..) | PredicateKind::Coerce(..) | PredicateKind::Clause(Clause::RegionOutlives(..)) | PredicateKind::WellFormed(..) | PredicateKind::ObjectSafe(..) | PredicateKind::ClosureKind(..) | PredicateKind::Clause(Clause::TypeOutlives(..)) | PredicateKind::ConstEvaluatable(..) | PredicateKind::ConstEquate(..) | PredicateKind::Ambiguous | PredicateKind::TypeWellFormedFromEnv(..) => None, } } pub fn to_opt_poly_projection_pred(self) -> Option> { let predicate = self.kind(); match predicate.skip_binder() { PredicateKind::Clause(Clause::Projection(t)) => Some(predicate.rebind(t)), PredicateKind::Clause(Clause::Trait(..)) | PredicateKind::Subtype(..) | PredicateKind::Coerce(..) | PredicateKind::Clause(Clause::RegionOutlives(..)) | PredicateKind::WellFormed(..) | PredicateKind::ObjectSafe(..) | PredicateKind::ClosureKind(..) | PredicateKind::Clause(Clause::TypeOutlives(..)) | PredicateKind::ConstEvaluatable(..) | PredicateKind::ConstEquate(..) | PredicateKind::Ambiguous | PredicateKind::TypeWellFormedFromEnv(..) => None, } } pub fn to_opt_type_outlives(self) -> Option> { let predicate = self.kind(); match predicate.skip_binder() { PredicateKind::Clause(Clause::TypeOutlives(data)) => Some(predicate.rebind(data)), PredicateKind::Clause(Clause::Trait(..)) | PredicateKind::Clause(Clause::Projection(..)) | PredicateKind::Subtype(..) | PredicateKind::Coerce(..) | PredicateKind::Clause(Clause::RegionOutlives(..)) | PredicateKind::WellFormed(..) | PredicateKind::ObjectSafe(..) | PredicateKind::ClosureKind(..) | PredicateKind::ConstEvaluatable(..) | PredicateKind::ConstEquate(..) | PredicateKind::Ambiguous | 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: /// ```ignore (illustrative) /// 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, TypeVisitable)] 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() } pub fn iter(&self) -> <&Self as IntoIterator>::IntoIter { (&self).into_iter() } } impl<'tcx> IntoIterator for InstantiatedPredicates<'tcx> { type Item = (Predicate<'tcx>, Span); type IntoIter = std::iter::Zip>, std::vec::IntoIter>; fn into_iter(self) -> Self::IntoIter { debug_assert_eq!(self.predicates.len(), self.spans.len()); std::iter::zip(self.predicates, self.spans) } } impl<'a, 'tcx> IntoIterator for &'a InstantiatedPredicates<'tcx> { type Item = (Predicate<'tcx>, Span); type IntoIter = std::iter::Zip< std::iter::Copied>>, std::iter::Copied>, >; fn into_iter(self) -> Self::IntoIter { debug_assert_eq!(self.predicates.len(), self.spans.len()); std::iter::zip(self.predicates.iter().copied(), self.spans.iter().copied()) } } #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable, Lift)] #[derive(TypeFoldable, TypeVisitable)] pub struct OpaqueTypeKey<'tcx> { pub def_id: LocalDefId, pub substs: SubstsRef<'tcx>, } #[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, HashStable, TyEncodable, TyDecodable)] pub struct OpaqueHiddenType<'tcx> { /// The span of this particular definition of the opaque type. So /// for example: /// /// ```ignore (incomplete snippet) /// type Foo = impl Baz; /// fn bar() -> Foo { /// // ^^^ This is the span we are looking for! /// } /// ``` /// /// In cases where the fn returns `(impl Trait, impl Trait)` or /// other such combinations, the result is currently /// over-approximated, but better than nothing. pub span: Span, /// The type variable that represents the value of the opaque type /// that we require. In other words, after we compile this function, /// we will be created a constraint like: /// ```ignore (pseudo-rust) /// Foo<'a, T> = ?C /// ``` /// where `?C` is the value of this type variable. =) It may /// naturally refer to the type and lifetime parameters in scope /// in this function, though ultimately it should only reference /// those that are arguments to `Foo` in the constraint above. (In /// other words, `?C` should not include `'b`, even though it's a /// lifetime parameter on `foo`.) pub ty: Ty<'tcx>, } impl<'tcx> OpaqueHiddenType<'tcx> { pub fn report_mismatch(&self, other: &Self, tcx: TyCtxt<'tcx>) { // Found different concrete types for the opaque type. let sub_diag = if self.span == other.span { TypeMismatchReason::ConflictType { span: self.span } } else { TypeMismatchReason::PreviousUse { span: self.span } }; tcx.sess.emit_err(OpaqueHiddenTypeMismatch { self_ty: self.ty, other_ty: other.ty, other_span: other.span, sub: sub_diag, }); } #[instrument(level = "debug", skip(tcx), ret)] pub fn remap_generic_params_to_declaration_params( self, opaque_type_key: OpaqueTypeKey<'tcx>, tcx: TyCtxt<'tcx>, // typeck errors have subpar spans for opaque types, so delay error reporting until borrowck. ignore_errors: bool, ) -> Self { let OpaqueTypeKey { def_id, substs } = opaque_type_key; // Use substs to build up a reverse map from regions to their // identity mappings. This is necessary because of `impl // Trait` lifetimes are computed by replacing existing // lifetimes with 'static and remapping only those used in the // `impl Trait` return type, resulting in the parameters // shifting. let id_substs = InternalSubsts::identity_for_item(tcx, def_id.to_def_id()); debug!(?id_substs); // This zip may have several times the same lifetime in `substs` paired with a different // lifetime from `id_substs`. Simply `collect`ing the iterator is the correct behaviour: // it will pick the last one, which is the one we introduced in the impl-trait desugaring. let map = substs.iter().zip(id_substs).collect(); debug!("map = {:#?}", map); // Convert the type from the function into a type valid outside // the function, by replacing invalid regions with 'static, // after producing an error for each of them. self.fold_with(&mut opaque_types::ReverseMapper::new(tcx, map, self.span, ignore_errors)) } } /// 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, PartialOrd, Ord)] #[derive(HashStable, TyEncodable, TyDecodable)] pub struct Placeholder { pub universe: UniverseIndex, pub name: T, } 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 potentially 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, TypeVisitable, 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>, ParamTag, true>, } #[derive(Copy, Clone)] struct ParamTag { reveal: traits::Reveal, constness: hir::Constness, } unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag { const BITS: usize = 2; #[inline] fn into_usize(self) -> usize { match self { Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0, Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1, Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2, Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3, } } #[inline] unsafe fn from_usize(ptr: usize) -> Self { match ptr { 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst }, 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst }, 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const }, 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const }, _ => 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()) .field("constness", &self.constness()) .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); self.constness().hash_stable(hcx, hasher); } } impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> { fn try_fold_with>( self, folder: &mut F, ) -> Result { Ok(ParamEnv::new( self.caller_bounds().try_fold_with(folder)?, self.reveal().try_fold_with(folder)?, self.constness(), )) } } impl<'tcx> TypeVisitable<'tcx> for ParamEnv<'tcx> { fn 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, hir::Constness::NotConst) } #[inline] pub fn caller_bounds(self) -> &'tcx List> { self.packed.pointer() } #[inline] pub fn reveal(self) -> traits::Reveal { self.packed.tag().reveal } #[inline] pub fn constness(self) -> hir::Constness { self.packed.tag().constness } #[inline] pub fn is_const(self) -> bool { self.packed.tag().constness == hir::Constness::Const } /// 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, hir::Constness::NotConst) } /// Construct a trait environment with the given set of predicates. #[inline] pub fn new( caller_bounds: &'tcx List>, reveal: Reveal, constness: hir::Constness, ) -> Self { ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) } } pub fn with_user_facing(mut self) -> Self { self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() }); self } #[inline] pub fn with_constness(mut self, constness: hir::Constness) -> Self { self.packed.set_tag(ParamTag { constness, ..self.packed.tag() }); self } #[inline] pub fn with_const(mut self) -> Self { self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() }); self } #[inline] pub fn without_const(mut self) -> Self { self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() }); self } #[inline] pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) { *self = self.with_constness(constness.and(self.constness())) } /// 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().reveal == traits::Reveal::All { return self; } ParamEnv::new( tcx.reveal_opaque_types_in_bounds(self.caller_bounds()), Reveal::All, self.constness(), ) } /// Returns this same environment but with no caller bounds. #[inline] pub fn without_caller_bounds(self) -> Self { Self::new(List::empty(), self.reveal(), self.constness()) } /// 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_global() { ParamEnvAnd { param_env: self.without_caller_bounds(), value } } else { ParamEnvAnd { param_env: self, value } } } } } } // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that // the constness of trait bounds is being propagated correctly. impl<'tcx> PolyTraitRef<'tcx> { #[inline] pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> { self.map_bound(|trait_ref| ty::TraitPredicate { trait_ref, constness, polarity: ty::ImplPolarity::Positive, }) } #[inline] pub fn without_const(self) -> PolyTraitPredicate<'tcx> { self.with_constness(BoundConstness::NotConst) } } #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable, TypeVisitable)] #[derive(HashStable, Lift)] 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) } #[inline] pub fn without_const(mut self) -> Self { self.param_env = self.param_env.without_const(); self } } #[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)] 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, TyEncodable, TyDecodable)] 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, TyEncodable, TyDecodable)] 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: Option<(CtorKind, DefId)>, /// Variant or struct name. pub name: Symbol, /// Discriminant of this variant. pub discr: VariantDiscr, /// Fields of this variant. pub fields: Vec, /// 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( name: Symbol, variant_did: Option, ctor: Option<(CtorKind, DefId)>, discr: VariantDiscr, fields: Vec, adt_kind: AdtKind, parent_did: DefId, recovered: bool, is_field_list_non_exhaustive: bool, ) -> Self { debug!( "VariantDef::new(name = {:?}, variant_did = {:?}, ctor = {:?}, discr = {:?}, fields = {:?}, adt_kind = {:?}, parent_did = {:?})", name, variant_did, ctor, discr, fields, 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, name, discr, fields, 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) } /// Computes the `Ident` of this variant by looking up the `Span` pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident { Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap()) } #[inline] pub fn ctor_kind(&self) -> Option { self.ctor.map(|(kind, _)| kind) } #[inline] pub fn ctor_def_id(&self) -> Option { self.ctor.map(|(_, def_id)| def_id) } } impl PartialEq for VariantDef { #[inline] fn eq(&self, other: &Self) -> bool { // There should be only one `VariantDef` for each `def_id`, therefore // it is fine to implement `PartialEq` only based on `def_id`. // // Below, we exhaustively destructure `self` and `other` so that if the // definition of `VariantDef` changes, a compile-error will be produced, // reminding us to revisit this assumption. let Self { def_id: lhs_def_id, ctor: _, name: _, discr: _, fields: _, flags: _ } = &self; let Self { def_id: rhs_def_id, ctor: _, name: _, discr: _, fields: _, flags: _ } = other; lhs_def_id == rhs_def_id } } impl Eq for VariantDef {} impl Hash for VariantDef { #[inline] fn hash(&self, s: &mut H) { // There should be only one `VariantDef` for each `def_id`, therefore // it is fine to implement `Hash` only based on `def_id`. // // Below, we exhaustively destructure `self` so that if the definition // of `VariantDef` changes, a compile-error will be produced, reminding // us to revisit this assumption. let Self { def_id, ctor: _, name: _, discr: _, fields: _, flags: _ } = &self; def_id.hash(s) } } #[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, TyEncodable, TyDecodable)] pub struct FieldDef { pub did: DefId, pub name: Symbol, pub vis: Visibility, } impl PartialEq for FieldDef { #[inline] fn eq(&self, other: &Self) -> bool { // There should be only one `FieldDef` for each `did`, therefore it is // fine to implement `PartialEq` only based on `did`. // // Below, we exhaustively destructure `self` so that if the definition // of `FieldDef` changes, a compile-error will be produced, reminding // us to revisit this assumption. let Self { did: lhs_did, name: _, vis: _ } = &self; let Self { did: rhs_did, name: _, vis: _ } = other; lhs_did == rhs_did } } impl Eq for FieldDef {} impl Hash for FieldDef { #[inline] fn hash(&self, s: &mut H) { // There should be only one `FieldDef` for each `did`, therefore it is // fine to implement `Hash` only based on `did`. // // Below, we exhaustively destructure `self` so that if the definition // of `FieldDef` changes, a compile-error will be produced, reminding // us to revisit this assumption. let Self { did, name: _, vis: _ } = &self; did.hash(s) } } 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::Adt`]. pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> { tcx.bound_type_of(self.did).subst(tcx, subst) } /// Computes the `Ident` of this variant by looking up the `Span` pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident { Ident::new(self.name, tcx.def_ident_span(self.did).unwrap()) } } pub type Attributes<'tcx> = impl Iterator; #[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: /// /// ```compile_fail,(E0119) /// 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(move |item| item.kind == AssocKind::Fn && item.defaultness(self).has_value()) } pub fn repr_options_of_def(self, 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 mut field_shuffle_seed = self.def_path_hash(did).0.to_smaller_hash(); // If the user defined a custom seed for layout randomization, xor the item's // path hash with the user defined seed, this will allowing determinism while // still allowing users to further randomize layout generation for e.g. fuzzing if let Some(user_seed) = self.sess.opts.unstable_opts.layout_seed { field_shuffle_seed ^= user_seed; } for attr in self.get_attrs(did, sym::repr) { for r in attr::parse_repr_attr(&self.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::ReprSimd => ReprFlags::IS_SIMD, attr::ReprInt(i) => { size = Some(match i { attr::IntType::SignedInt(x) => match x { ast::IntTy::Isize => IntegerType::Pointer(true), ast::IntTy::I8 => IntegerType::Fixed(Integer::I8, true), ast::IntTy::I16 => IntegerType::Fixed(Integer::I16, true), ast::IntTy::I32 => IntegerType::Fixed(Integer::I32, true), ast::IntTy::I64 => IntegerType::Fixed(Integer::I64, true), ast::IntTy::I128 => IntegerType::Fixed(Integer::I128, true), }, attr::IntType::UnsignedInt(x) => match x { ast::UintTy::Usize => IntegerType::Pointer(false), ast::UintTy::U8 => IntegerType::Fixed(Integer::I8, false), ast::UintTy::U16 => IntegerType::Fixed(Integer::I16, false), ast::UintTy::U32 => IntegerType::Fixed(Integer::I32, false), ast::UintTy::U64 => IntegerType::Fixed(Integer::I64, false), ast::UintTy::U128 => IntegerType::Fixed(Integer::I128, false), }, }); 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 self.sess.opts.unstable_opts.randomize_layout { flags.insert(ReprFlags::RANDOMIZE_LAYOUT); } // This is here instead of layout because the choice must make it into metadata. if !self.consider_optimizing(|| format!("Reorder fields of {:?}", self.def_path_str(did))) { flags.insert(ReprFlags::IS_LINEAR); } ReprOptions { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed } } /// Look up the name of a definition across crates. This does not look at HIR. pub fn opt_item_name(self, def_id: DefId) -> Option { if let Some(cnum) = def_id.as_crate_root() { Some(self.crate_name(cnum)) } 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 .opt_item_name(DefId { krate: def_id.krate, index: def_key.parent.unwrap() }), // The name of opaque types only exists in HIR. rustc_hir::definitions::DefPathData::ImplTrait if let Some(def_id) = def_id.as_local() => self.hir().opt_name(self.hir().local_def_id_to_hir_id(def_id)), _ => def_key.get_opt_name(), } } } /// Look up the name of a definition across crates. This does not look at HIR. /// /// This method will ICE if the corresponding item does not have a name. In these cases, use /// [`opt_item_name`] instead. /// /// [`opt_item_name`]: Self::opt_item_name pub fn item_name(self, id: DefId) -> Symbol { self.opt_item_name(id).unwrap_or_else(|| { bug!("item_name: no name for {:?}", self.def_path(id)); }) } /// Look up the name and span of a definition. /// /// See [`item_name`][Self::item_name] for more information. pub fn opt_item_ident(self, def_id: DefId) -> Option { let def = self.opt_item_name(def_id)?; let span = def_id .as_local() .and_then(|id| self.def_ident_span(id)) .unwrap_or(rustc_span::DUMMY_SP); Some(Ident::new(def, 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 find_field_index(self, ident: Ident, variant: &VariantDef) -> Option { variant .fields .iter() .position(|field| self.hygienic_eq(ident, field.ident(self), 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.subst_identity().references_error()) || self .impl_trait_ref(def_id2) .map_or(false, |tr| tr.subst_identity().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.skip_binder().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); 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); let enum_did = self.parent(variant_did); 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); 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. #[instrument(skip(self), level = "debug")] pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> { match instance { ty::InstanceDef::Item(def) => { debug!("calling def_kind on def: {:?}", def); let def_kind = self.def_kind(def.did); debug!("returned from def_kind: {:?}", def_kind); match def_kind { DefKind::Const | DefKind::Static(..) | DefKind::AssocConst | DefKind::Ctor(..) | DefKind::AnonConst | DefKind::InlineConst => 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), } } // FIXME(@lcnr): Remove this function. pub fn get_attrs_unchecked(self, did: DefId) -> &'tcx [ast::Attribute] { if let Some(did) = did.as_local() { self.hir().attrs(self.hir().local_def_id_to_hir_id(did)) } else { self.item_attrs(did) } } /// Gets all attributes with the given name. pub fn get_attrs(self, did: DefId, attr: Symbol) -> ty::Attributes<'tcx> { let filter_fn = move |a: &&ast::Attribute| a.has_name(attr); if let Some(did) = did.as_local() { self.hir().attrs(self.hir().local_def_id_to_hir_id(did)).iter().filter(filter_fn) } else if cfg!(debug_assertions) && rustc_feature::is_builtin_only_local(attr) { bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr); } else { self.item_attrs(did).iter().filter(filter_fn) } } pub fn get_attr(self, did: DefId, attr: Symbol) -> Option<&'tcx ast::Attribute> { if cfg!(debug_assertions) && !rustc_feature::is_valid_for_get_attr(attr) { bug!("get_attr: unexpected called with DefId `{:?}`, attr `{:?}`", did, attr); } else { self.get_attrs(did, attr).next() } } /// Determines whether an item is annotated with an attribute. pub fn has_attr(self, did: DefId, attr: Symbol) -> bool { if cfg!(debug_assertions) && !did.is_local() && rustc_feature::is_builtin_only_local(attr) { bug!("tried to access the `only_local` attribute `{}` from an extern crate", attr); } else { self.get_attrs(did, attr).next().is_some() } } /// 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 `true` if this is a trait alias. pub fn trait_is_alias(self, trait_def_id: DefId) -> bool { self.def_kind(trait_def_id) == DefKind::TraitAlias } pub fn trait_is_coinductive(self, trait_def_id: DefId) -> bool { self.trait_is_auto(trait_def_id) || self.lang_items().sized_trait() == Some(trait_def_id) } /// 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.skip_binder().def_id) } /// If the given `DefId` describes an item belonging to a trait, /// returns the `DefId` of the trait that the trait item belongs to; /// otherwise, returns `None`. pub fn trait_of_item(self, def_id: DefId) -> Option { if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) { let parent = self.parent(def_id); if let DefKind::Trait | DefKind::TraitAlias = self.def_kind(parent) { return Some(parent); } } None } /// 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 { if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) { let parent = self.parent(def_id); if let DefKind::Impl = self.def_kind(parent) { return Some(parent); } } None } /// If the given `DefId` belongs to a trait that was automatically derived, returns `true`. pub fn is_builtin_derive(self, def_id: DefId) -> bool { self.has_attr(def_id, sym::automatically_derived) } /// 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_def_id: DefId) -> Result { if let Some(impl_def_id) = impl_def_id.as_local() { Ok(self.def_span(impl_def_id)) } else { Err(self.crate_name(impl_def_id.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) } /// Returns `true` if the debuginfo for `span` should be collapsed to the outermost expansion /// site. Only applies when `Span` is the result of macro expansion. /// /// - If the `collapse_debuginfo` feature is enabled then debuginfo is not collapsed by default /// and only when a macro definition is annotated with `#[collapse_debuginfo]`. /// - If `collapse_debuginfo` is not enabled, then debuginfo is collapsed by default. /// /// When `-Zdebug-macros` is provided then debuginfo will never be collapsed. pub fn should_collapse_debuginfo(self, span: Span) -> bool { !self.sess.opts.unstable_opts.debug_macros && if self.features().collapse_debuginfo { span.in_macro_expansion_with_collapse_debuginfo() } else { // Inlined spans should not be collapsed as that leads to all of the // inlined code being attributed to the inline callsite. span.from_expansion() && !span.is_inlined() } } pub fn is_object_safe(self, key: DefId) -> bool { self.object_safety_violations(key).is_empty() } #[inline] pub fn is_const_fn_raw(self, def_id: DefId) -> bool { matches!( self.def_kind(def_id), DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(..) | DefKind::Closure ) && self.constness(def_id) == hir::Constness::Const } #[inline] pub fn is_const_default_method(self, def_id: DefId) -> bool { matches!(self.trait_of_item(def_id), Some(trait_id) if self.has_attr(trait_id, sym::const_trait)) } pub fn impl_trait_in_trait_parent(self, mut def_id: DefId) -> DefId { while let def_kind = self.def_kind(def_id) && def_kind != DefKind::AssocFn { debug_assert_eq!(def_kind, DefKind::ImplTraitPlaceholder); def_id = self.parent(def_id); } def_id } } /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition. pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option { let def_id = def_id.as_local()?; if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) { if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind { return match opaque_ty.origin { hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => { Some(parent) } hir::OpaqueTyOrigin::TyAlias => None, }; } } 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); inhabitedness::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, incoherent_impls: trait_def::incoherent_impls_provider, const_param_default: consts::const_param_default, vtable_allocation: vtable::vtable_allocation_provider, ..*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>, pub incoherent_impls: FxHashMap>, } #[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, } /// The constituent parts of a type level constant of kind ADT or array. #[derive(Copy, Clone, Debug, HashStable)] pub struct DestructuredConst<'tcx> { pub variant: Option, pub fields: &'tcx [ty::Const<'tcx>], } // Some types are used a lot. Make sure they don't unintentionally get bigger. #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))] mod size_asserts { use super::*; use rustc_data_structures::static_assert_size; // tidy-alphabetical-start static_assert_size!(PredicateKind<'_>, 32); static_assert_size!(WithCachedTypeInfo>, 56); // tidy-alphabetical-end }