// Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. pub use self::Variance::*; pub use self::AssociatedItemContainer::*; pub use self::BorrowKind::*; pub use self::IntVarValue::*; pub use self::LvaluePreference::*; pub use self::fold::TypeFoldable; use hir::{map as hir_map, FreevarMap, TraitMap}; use hir::def::{Def, CtorKind, ExportMap}; use hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE}; use ich::StableHashingContext; use middle::const_val::ConstVal; use middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem}; use middle::privacy::AccessLevels; use middle::resolve_lifetime::ObjectLifetimeDefault; use middle::region::CodeExtent; use mir::Mir; use traits; use ty; use ty::subst::{Subst, Substs}; use ty::util::IntTypeExt; use ty::walk::TypeWalker; use util::common::ErrorReported; use util::nodemap::{NodeSet, DefIdMap, FxHashMap, FxHashSet}; use serialize::{self, Encodable, Encoder}; use std::collections::BTreeMap; use std::cmp; use std::fmt; use std::hash::{Hash, Hasher}; use std::iter::FromIterator; use std::ops::Deref; use std::rc::Rc; use std::slice; use std::vec::IntoIter; use std::mem; use syntax::ast::{self, DUMMY_NODE_ID, Name, Ident, NodeId}; use syntax::attr; use syntax::ext::hygiene::{Mark, SyntaxContext}; use syntax::symbol::{Symbol, InternedString}; use syntax_pos::{DUMMY_SP, Span}; use rustc_const_math::ConstInt; use rustc_data_structures::accumulate_vec::IntoIter as AccIntoIter; use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult, HashStable}; use rustc_data_structures::transitive_relation::TransitiveRelation; use hir; pub use self::sty::{Binder, DebruijnIndex}; pub use self::sty::{FnSig, PolyFnSig}; pub use self::sty::{InferTy, ParamTy, ProjectionTy, ExistentialPredicate}; pub use self::sty::{ClosureSubsts, TypeAndMut}; pub use self::sty::{TraitRef, TypeVariants, PolyTraitRef}; pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef}; pub use self::sty::{ExistentialProjection, PolyExistentialProjection}; pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region}; pub use self::sty::RegionKind; pub use self::sty::{TyVid, IntVid, FloatVid, RegionVid, SkolemizedRegionVid}; pub use self::sty::BoundRegion::*; pub use self::sty::InferTy::*; pub use self::sty::RegionKind::*; pub use self::sty::TypeVariants::*; pub use self::binding::BindingMode; pub use self::binding::BindingMode::*; pub use self::context::{TyCtxt, GlobalArenas, tls}; pub use self::context::{Lift, TypeckTables}; pub use self::instance::{Instance, InstanceDef}; pub use self::trait_def::TraitDef; pub use self::maps::queries; pub mod adjustment; pub mod binding; pub mod cast; pub mod error; pub mod fast_reject; pub mod fold; pub mod inhabitedness; pub mod item_path; pub mod layout; pub mod _match; pub mod maps; pub mod outlives; pub mod relate; pub mod steal; pub mod subst; pub mod trait_def; pub mod walk; pub mod wf; pub mod util; mod context; mod flags; mod instance; mod structural_impls; mod sty; // Data types /// The complete set of all analyses described in this module. This is /// produced by the driver and fed to trans and later passes. /// /// NB: These contents are being migrated into queries using the /// *on-demand* infrastructure. #[derive(Clone)] pub struct CrateAnalysis { pub access_levels: Rc, pub reachable: Rc, pub name: String, pub glob_map: Option, } #[derive(Clone)] pub struct Resolutions { pub freevars: FreevarMap, pub trait_map: TraitMap, pub maybe_unused_trait_imports: NodeSet, pub export_map: ExportMap, } #[derive(Clone, Copy, PartialEq, Eq, Debug)] pub enum AssociatedItemContainer { TraitContainer(DefId), ImplContainer(DefId), } impl AssociatedItemContainer { pub fn id(&self) -> DefId { match *self { TraitContainer(id) => id, ImplContainer(id) => id, } } } /// 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, PartialEq, Eq, Hash, Debug)] pub struct ImplHeader<'tcx> { pub impl_def_id: DefId, pub self_ty: Ty<'tcx>, pub trait_ref: Option>, pub predicates: Vec>, } #[derive(Copy, Clone, Debug, PartialEq, Eq)] pub struct AssociatedItem { pub def_id: DefId, pub name: Name, pub kind: AssociatedKind, pub vis: Visibility, pub defaultness: hir::Defaultness, pub container: AssociatedItemContainer, /// Whether this is a method with an explicit self /// as its first argument, allowing method calls. pub method_has_self_argument: bool, } #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash, RustcEncodable, RustcDecodable)] pub enum AssociatedKind { Const, Method, Type } impl AssociatedItem { pub fn def(&self) -> Def { match self.kind { AssociatedKind::Const => Def::AssociatedConst(self.def_id), AssociatedKind::Method => Def::Method(self.def_id), AssociatedKind::Type => Def::AssociatedTy(self.def_id), } } /// Tests whether the associated item admits a non-trivial implementation /// for ! pub fn relevant_for_never<'tcx>(&self) -> bool { match self.kind { AssociatedKind::Const => true, AssociatedKind::Type => true, // FIXME(canndrew): Be more thorough here, check if any argument is uninhabited. AssociatedKind::Method => !self.method_has_self_argument, } } pub fn signature<'a, 'tcx>(&self, tcx: &TyCtxt<'a, 'tcx, 'tcx>) -> String { match self.kind { ty::AssociatedKind::Method => { // We skip the binder here because the binder would deanonymize all // late-bound regions, and we don't want method signatures to show up // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound // regions just fine, showing `fn(&MyType)`. format!("{}", tcx.fn_sig(self.def_id).skip_binder()) } ty::AssociatedKind::Type => format!("type {};", self.name.to_string()), ty::AssociatedKind::Const => { format!("const {}: {:?};", self.name.to_string(), tcx.type_of(self.def_id)) } } } } #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable)] 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, } 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<'a, 'gcx, 'tcx> DefIdTree for TyCtxt<'a, 'gcx, 'tcx> { fn parent(self, id: DefId) -> Option { self.def_key(id).parent.map(|index| DefId { index: index, ..id }) } } impl Visibility { pub fn from_hir(visibility: &hir::Visibility, id: NodeId, tcx: TyCtxt) -> Self { match *visibility { hir::Public => Visibility::Public, hir::Visibility::Crate => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)), hir::Visibility::Restricted { ref path, .. } => match path.def { // 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. Def::Err => Visibility::Public, def => Visibility::Restricted(def.def_id()), }, hir::Inherited => { Visibility::Restricted(tcx.hir.get_module_parent(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) } } #[derive(Clone, PartialEq, RustcDecodable, RustcEncodable, Copy)] pub enum Variance { Covariant, // T <: T iff A <: B -- e.g., function return type Invariant, // T <: T iff B == A -- e.g., type of mutable cell Contravariant, // T <: T iff B <: A -- e.g., function param type Bivariant, // T <: T -- e.g., unused type parameter } /// 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. pub struct CrateVariancesMap { /// This relation tracks the dependencies between the variance of /// various items. In particular, if `a < b`, then the variance of /// `a` depends on the sources of `b`. pub dependencies: TransitiveRelation, /// 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>>, /// An empty vector, useful for cloning. pub empty_variance: Rc>, } impl Variance { /// `a.xform(b)` combines the variance of a context with the /// variance of a type with the following meaning. If we are in a /// context with variance `a`, and we encounter a type argument in /// a position with variance `b`, then `a.xform(b)` is the new /// variance with which the argument appears. /// /// Example 1: /// /// *mut Vec /// /// Here, the "ambient" variance starts as covariant. `*mut T` is /// invariant with respect to `T`, so the variance in which the /// `Vec` appears is `Covariant.xform(Invariant)`, which /// yields `Invariant`. Now, the type `Vec` is covariant with /// respect to its type argument `T`, and hence the variance of /// the `i32` here is `Invariant.xform(Covariant)`, which results /// (again) in `Invariant`. /// /// Example 2: /// /// fn(*const Vec, *mut Vec` appears is /// `Contravariant.xform(Covariant)` or `Contravariant`. The same /// is true for its `i32` argument. In the `*mut T` case, the /// variance of `Vec` is `Contravariant.xform(Invariant)`, /// and hence the outermost type is `Invariant` with respect to /// `Vec` (and its `i32` argument). /// /// Source: Figure 1 of "Taming the Wildcards: /// Combining Definition- and Use-Site Variance" published in PLDI'11. pub fn xform(self, v: ty::Variance) -> ty::Variance { match (self, v) { // Figure 1, column 1. (ty::Covariant, ty::Covariant) => ty::Covariant, (ty::Covariant, ty::Contravariant) => ty::Contravariant, (ty::Covariant, ty::Invariant) => ty::Invariant, (ty::Covariant, ty::Bivariant) => ty::Bivariant, // Figure 1, column 2. (ty::Contravariant, ty::Covariant) => ty::Contravariant, (ty::Contravariant, ty::Contravariant) => ty::Covariant, (ty::Contravariant, ty::Invariant) => ty::Invariant, (ty::Contravariant, ty::Bivariant) => ty::Bivariant, // Figure 1, column 3. (ty::Invariant, _) => ty::Invariant, // Figure 1, column 4. (ty::Bivariant, _) => ty::Bivariant, } } } // 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: CrateNum, pub pos: usize, } // Flags that we track on types. These flags are propagated upwards // through the type during type construction, so that we can quickly // check whether the type has various kinds of types in it without // recursing over the type itself. bitflags! { flags TypeFlags: u32 { const HAS_PARAMS = 1 << 0, const HAS_SELF = 1 << 1, const HAS_TY_INFER = 1 << 2, const HAS_RE_INFER = 1 << 3, const HAS_RE_SKOL = 1 << 4, const HAS_RE_EARLY_BOUND = 1 << 5, const HAS_FREE_REGIONS = 1 << 6, const HAS_TY_ERR = 1 << 7, const HAS_PROJECTION = 1 << 8, const HAS_TY_CLOSURE = 1 << 9, // true if there are "names" of types and regions and so forth // that are local to a particular fn const HAS_LOCAL_NAMES = 1 << 10, // Present if the type belongs in a local type context. // Only set for TyInfer other than Fresh. const KEEP_IN_LOCAL_TCX = 1 << 11, // Is there a projection that does not involve a bound region? // Currently we can't normalize projections w/ bound regions. const HAS_NORMALIZABLE_PROJECTION = 1 << 12, const NEEDS_SUBST = TypeFlags::HAS_PARAMS.bits | TypeFlags::HAS_SELF.bits | TypeFlags::HAS_RE_EARLY_BOUND.bits, // Flags representing the nominal content of a type, // computed by FlagsComputation. If you add a new nominal // flag, it should be added here too. const NOMINAL_FLAGS = TypeFlags::HAS_PARAMS.bits | TypeFlags::HAS_SELF.bits | TypeFlags::HAS_TY_INFER.bits | TypeFlags::HAS_RE_INFER.bits | TypeFlags::HAS_RE_SKOL.bits | TypeFlags::HAS_RE_EARLY_BOUND.bits | TypeFlags::HAS_FREE_REGIONS.bits | TypeFlags::HAS_TY_ERR.bits | TypeFlags::HAS_PROJECTION.bits | TypeFlags::HAS_TY_CLOSURE.bits | TypeFlags::HAS_LOCAL_NAMES.bits | TypeFlags::KEEP_IN_LOCAL_TCX.bits, } } pub struct TyS<'tcx> { pub sty: TypeVariants<'tcx>, pub flags: TypeFlags, // the maximal depth of any bound regions appearing in this type. region_depth: u32, } impl<'tcx> PartialEq for TyS<'tcx> { #[inline] fn eq(&self, other: &TyS<'tcx>) -> bool { // (self as *const _) == (other as *const _) (self as *const TyS<'tcx>) == (other as *const TyS<'tcx>) } } 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<'tcx> TyS<'tcx> { pub fn is_primitive_ty(&self) -> bool { match self.sty { TypeVariants::TyBool | TypeVariants::TyChar | TypeVariants::TyInt(_) | TypeVariants::TyUint(_) | TypeVariants::TyFloat(_) | TypeVariants::TyInfer(InferTy::IntVar(_)) | TypeVariants::TyInfer(InferTy::FloatVar(_)) | TypeVariants::TyInfer(InferTy::FreshIntTy(_)) | TypeVariants::TyInfer(InferTy::FreshFloatTy(_)) => true, TypeVariants::TyRef(_, x) => x.ty.is_primitive_ty(), _ => false, } } pub fn is_suggestable(&self) -> bool { match self.sty { TypeVariants::TyAnon(..) | TypeVariants::TyFnDef(..) | TypeVariants::TyFnPtr(..) | TypeVariants::TyDynamic(..) | TypeVariants::TyClosure(..) | TypeVariants::TyProjection(..) => false, _ => true, } } } impl<'a, 'gcx, 'tcx> HashStable> for ty::TyS<'tcx> { fn hash_stable(&self, hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>, hasher: &mut StableHasher) { let ty::TyS { ref sty, // The other fields just provide fast access to information that is // also contained in `sty`, so no need to hash them. flags: _, region_depth: _, } = *self; sty.hash_stable(hcx, hasher); } } pub type Ty<'tcx> = &'tcx TyS<'tcx>; impl<'tcx> serialize::UseSpecializedEncodable for Ty<'tcx> {} impl<'tcx> serialize::UseSpecializedDecodable for Ty<'tcx> {} /// A wrapper for slices with the additional invariant /// that the slice is interned and no other slice with /// the same contents can exist in the same context. /// This means we can use pointer + length for both /// equality comparisons and hashing. #[derive(Debug, RustcEncodable)] pub struct Slice([T]); impl PartialEq for Slice { #[inline] fn eq(&self, other: &Slice) -> bool { (&self.0 as *const [T]) == (&other.0 as *const [T]) } } impl Eq for Slice {} impl Hash for Slice { fn hash(&self, s: &mut H) { (self.as_ptr(), self.len()).hash(s) } } impl Deref for Slice { type Target = [T]; fn deref(&self) -> &[T] { &self.0 } } impl<'a, T> IntoIterator for &'a Slice { type Item = &'a T; type IntoIter = <&'a [T] as IntoIterator>::IntoIter; fn into_iter(self) -> Self::IntoIter { self[..].iter() } } impl<'tcx> serialize::UseSpecializedDecodable for &'tcx Slice> {} impl Slice { pub fn empty<'a>() -> &'a Slice { unsafe { mem::transmute(slice::from_raw_parts(0x1 as *const T, 0)) } } } /// Upvars do not get their own node-id. Instead, we use the pair of /// the original var id (that is, the root variable that is referenced /// by the upvar) and the id of the closure expression. #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)] pub struct UpvarId { pub var_id: NodeId, pub closure_expr_id: NodeId, } #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, Copy)] pub enum BorrowKind { /// Data must be immutable and is aliasable. ImmBorrow, /// Data must be immutable but not aliasable. This kind of borrow /// cannot currently be expressed by the user and is used only in /// implicit closure bindings. It is needed when the closure /// is borrowing or mutating a mutable referent, e.g.: /// /// let x: &mut isize = ...; /// let y = || *x += 5; /// /// If we were to try to translate this closure into a more explicit /// form, we'd encounter an error with the code as written: /// /// struct Env { x: & &mut isize } /// let x: &mut isize = ...; /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn /// fn fn_ptr(env: &mut Env) { **env.x += 5; } /// /// This is then illegal because you cannot mutate a `&mut` found /// in an aliasable location. To solve, you'd have to translate with /// an `&mut` borrow: /// /// struct Env { x: & &mut isize } /// let x: &mut isize = ...; /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x /// fn fn_ptr(env: &mut Env) { **env.x += 5; } /// /// Now the assignment to `**env.x` is legal, but creating a /// mutable pointer to `x` is not because `x` is not mutable. We /// could fix this by declaring `x` as `let mut x`. This is ok in /// user code, if awkward, but extra weird for closures, since the /// borrow is hidden. /// /// So we introduce a "unique imm" borrow -- the referent is /// immutable, but not aliasable. This solves the problem. For /// simplicity, we don't give users the way to express this /// borrow, it's just used when translating closures. UniqueImmBorrow, /// Data is mutable and not aliasable. MutBorrow } /// Information describing the capture of an upvar. This is computed /// during `typeck`, specifically by `regionck`. #[derive(PartialEq, Clone, Debug, Copy, RustcEncodable, RustcDecodable)] pub enum UpvarCapture<'tcx> { /// Upvar is captured by value. This is always true when the /// closure is labeled `move`, but can also be true in other cases /// depending on inference. ByValue, /// Upvar is captured by reference. ByRef(UpvarBorrow<'tcx>), } #[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable)] pub struct UpvarBorrow<'tcx> { /// The kind of borrow: by-ref upvars have access to shared /// immutable borrows, which are not part of the normal language /// syntax. pub kind: BorrowKind, /// Region of the resulting reference. pub region: ty::Region<'tcx>, } pub type UpvarCaptureMap<'tcx> = FxHashMap>; #[derive(Copy, Clone)] pub struct ClosureUpvar<'tcx> { pub def: Def, pub span: Span, pub ty: Ty<'tcx>, } #[derive(Clone, Copy, PartialEq)] pub enum IntVarValue { IntType(ast::IntTy), UintType(ast::UintTy), } #[derive(Copy, Clone, RustcEncodable, RustcDecodable)] pub struct TypeParameterDef { pub name: Name, pub def_id: DefId, pub index: u32, pub has_default: bool, pub object_lifetime_default: ObjectLifetimeDefault, /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute /// on generic parameter `T`, asserts data behind the parameter /// `T` won't be accessed during the parent type's `Drop` impl. pub pure_wrt_drop: bool, } #[derive(Copy, Clone, RustcEncodable, RustcDecodable)] pub struct RegionParameterDef { pub name: Name, pub def_id: DefId, pub index: u32, /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute /// on generic parameter `'a`, asserts data of lifetime `'a` /// won't be accessed during the parent type's `Drop` impl. pub pure_wrt_drop: bool, } impl RegionParameterDef { pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion { ty::EarlyBoundRegion { def_id: self.def_id, index: self.index, name: self.name, } } pub fn to_bound_region(&self) -> ty::BoundRegion { self.to_early_bound_region_data().to_bound_region() } } impl ty::EarlyBoundRegion { pub fn to_bound_region(&self) -> ty::BoundRegion { ty::BoundRegion::BrNamed(self.def_id, self.name) } } /// Information about the formal type/lifetime parameters associated /// with an item or method. Analogous to hir::Generics. #[derive(Clone, Debug, RustcEncodable, RustcDecodable)] pub struct Generics { pub parent: Option, pub parent_regions: u32, pub parent_types: u32, pub regions: Vec, pub types: Vec, /// Reverse map to each `TypeParameterDef`'s `index` field, from /// `def_id.index` (`def_id.krate` is the same as the item's). pub type_param_to_index: BTreeMap, pub has_self: bool, pub has_late_bound_regions: Option, } impl Generics { pub fn parent_count(&self) -> usize { self.parent_regions as usize + self.parent_types as usize } pub fn own_count(&self) -> usize { self.regions.len() + self.types.len() } pub fn count(&self) -> usize { self.parent_count() + self.own_count() } pub fn region_param(&self, param: &EarlyBoundRegion) -> &RegionParameterDef { assert_eq!(self.parent_count(), 0); &self.regions[param.index as usize - self.has_self as usize] } pub fn type_param(&self, param: &ParamTy) -> &TypeParameterDef { assert_eq!(self.parent_count(), 0); &self.types[param.idx as usize - self.has_self as usize - self.regions.len()] } } /// Bounds on generics. #[derive(Clone, Default)] pub struct GenericPredicates<'tcx> { pub parent: Option, pub predicates: Vec>, } impl<'tcx> serialize::UseSpecializedEncodable for GenericPredicates<'tcx> {} impl<'tcx> serialize::UseSpecializedDecodable for GenericPredicates<'tcx> {} impl<'a, 'gcx, 'tcx> GenericPredicates<'tcx> { pub fn instantiate(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>) -> InstantiatedPredicates<'tcx> { let mut instantiated = InstantiatedPredicates::empty(); self.instantiate_into(tcx, &mut instantiated, substs); instantiated } pub fn instantiate_own(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, substs: &Substs<'tcx>) -> InstantiatedPredicates<'tcx> { InstantiatedPredicates { predicates: self.predicates.subst(tcx, substs) } } fn instantiate_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, instantiated: &mut InstantiatedPredicates<'tcx>, substs: &Substs<'tcx>) { if let Some(def_id) = self.parent { tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs); } instantiated.predicates.extend(self.predicates.iter().map(|p| p.subst(tcx, substs))) } pub fn instantiate_identity(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> InstantiatedPredicates<'tcx> { let mut instantiated = InstantiatedPredicates::empty(); self.instantiate_identity_into(tcx, &mut instantiated); instantiated } fn instantiate_identity_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, instantiated: &mut InstantiatedPredicates<'tcx>) { if let Some(def_id) = self.parent { tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated); } instantiated.predicates.extend(&self.predicates) } pub fn instantiate_supertrait(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, poly_trait_ref: &ty::PolyTraitRef<'tcx>) -> InstantiatedPredicates<'tcx> { assert_eq!(self.parent, None); InstantiatedPredicates { predicates: self.predicates.iter().map(|pred| { pred.subst_supertrait(tcx, poly_trait_ref) }).collect() } } } #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)] pub enum Predicate<'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(PolyTraitPredicate<'tcx>), /// where `T1 == T2`. Equate(PolyEquatePredicate<'tcx>), /// where 'a : 'b RegionOutlives(PolyRegionOutlivesPredicate<'tcx>), /// where T : 'a TypeOutlives(PolyTypeOutlivesPredicate<'tcx>), /// where ::Name == X, approximately. /// See `ProjectionPredicate` struct for details. Projection(PolyProjectionPredicate<'tcx>), /// no syntax: T WF WellFormed(Ty<'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, ClosureKind), /// `T1 <: T2` Subtype(PolySubtypePredicate<'tcx>), } impl<'a, 'gcx, '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<'a, 'gcx, 'tcx>, trait_ref: &ty::PolyTraitRef<'tcx>) -> ty::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 super-trait-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). let substs = &trait_ref.0.substs; match *self { Predicate::Trait(ty::Binder(ref data)) => Predicate::Trait(ty::Binder(data.subst(tcx, substs))), Predicate::Equate(ty::Binder(ref data)) => Predicate::Equate(ty::Binder(data.subst(tcx, substs))), Predicate::Subtype(ty::Binder(ref data)) => Predicate::Subtype(ty::Binder(data.subst(tcx, substs))), Predicate::RegionOutlives(ty::Binder(ref data)) => Predicate::RegionOutlives(ty::Binder(data.subst(tcx, substs))), Predicate::TypeOutlives(ty::Binder(ref data)) => Predicate::TypeOutlives(ty::Binder(data.subst(tcx, substs))), Predicate::Projection(ty::Binder(ref data)) => Predicate::Projection(ty::Binder(data.subst(tcx, substs))), Predicate::WellFormed(data) => Predicate::WellFormed(data.subst(tcx, substs)), Predicate::ObjectSafe(trait_def_id) => Predicate::ObjectSafe(trait_def_id), Predicate::ClosureKind(closure_def_id, kind) => Predicate::ClosureKind(closure_def_id, kind), } } } #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)] pub struct TraitPredicate<'tcx> { pub trait_ref: TraitRef<'tcx> } pub type PolyTraitPredicate<'tcx> = ty::Binder>; impl<'tcx> TraitPredicate<'tcx> { pub fn def_id(&self) -> DefId { self.trait_ref.def_id } pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator> + 'a { self.trait_ref.input_types() } 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 def-id does not care about regions self.0.def_id() } } #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] pub struct EquatePredicate<'tcx>(pub Ty<'tcx>, pub Ty<'tcx>); // `0 == 1` pub type PolyEquatePredicate<'tcx> = ty::Binder>; #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] pub struct OutlivesPredicate(pub A, pub B); // `A : B` pub type PolyOutlivesPredicate = ty::Binder>; pub type PolyRegionOutlivesPredicate<'tcx> = PolyOutlivesPredicate, ty::Region<'tcx>>; pub type PolyTypeOutlivesPredicate<'tcx> = PolyOutlivesPredicate, ty::Region<'tcx>>; #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] pub struct SubtypePredicate<'tcx> { pub a_is_expected: bool, pub a: Ty<'tcx>, pub b: Ty<'tcx> } pub type PolySubtypePredicate<'tcx> = ty::Binder>; /// 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, RustcEncodable, RustcDecodable)] pub struct ProjectionPredicate<'tcx> { pub projection_ty: ProjectionTy<'tcx>, pub ty: Ty<'tcx>, } pub type PolyProjectionPredicate<'tcx> = Binder>; impl<'tcx> PolyProjectionPredicate<'tcx> { pub fn to_poly_trait_ref(&self, tcx: TyCtxt) -> 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. ty::Binder(self.0.projection_ty.trait_ref(tcx)) } } pub trait ToPolyTraitRef<'tcx> { fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>; } impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> { fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> { assert!(!self.has_escaping_regions()); ty::Binder(self.clone()) } } 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) -> Predicate<'tcx>; } impl<'tcx> ToPredicate<'tcx> for TraitRef<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { // we're about to add a binder, so let's check that we don't // accidentally capture anything, or else that might be some // weird debruijn accounting. assert!(!self.has_escaping_regions()); ty::Predicate::Trait(ty::Binder(ty::TraitPredicate { trait_ref: self.clone() })) } } impl<'tcx> ToPredicate<'tcx> for PolyTraitRef<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { ty::Predicate::Trait(self.to_poly_trait_predicate()) } } impl<'tcx> ToPredicate<'tcx> for PolyEquatePredicate<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { Predicate::Equate(self.clone()) } } impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { Predicate::RegionOutlives(self.clone()) } } impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { Predicate::TypeOutlives(self.clone()) } } impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> { fn to_predicate(&self) -> Predicate<'tcx> { Predicate::Projection(self.clone()) } } impl<'tcx> Predicate<'tcx> { /// Iterates over the types in this predicate. Note that in all /// cases this is skipping over a binder, so late-bound regions /// with depth 0 are bound by the predicate. pub fn walk_tys(&self) -> IntoIter> { let vec: Vec<_> = match *self { ty::Predicate::Trait(ref data) => { data.skip_binder().input_types().collect() } ty::Predicate::Equate(ty::Binder(ref data)) => { vec![data.0, data.1] } ty::Predicate::Subtype(ty::Binder(SubtypePredicate { a, b, a_is_expected: _ })) => { vec![a, b] } ty::Predicate::TypeOutlives(ty::Binder(ref data)) => { vec![data.0] } ty::Predicate::RegionOutlives(..) => { vec![] } ty::Predicate::Projection(ref data) => { data.0.projection_ty.substs.types().chain(Some(data.0.ty)).collect() } ty::Predicate::WellFormed(data) => { vec![data] } ty::Predicate::ObjectSafe(_trait_def_id) => { vec![] } ty::Predicate::ClosureKind(_closure_def_id, _kind) => { vec![] } }; // The only reason to collect into a vector here is that I was // too lazy to make the full (somewhat complicated) iterator // type that would be needed here. But I wanted this fn to // return an iterator conceptually, rather than a `Vec`, so as // to be closer to `Ty::walk`. vec.into_iter() } pub fn to_opt_poly_trait_ref(&self) -> Option> { match *self { Predicate::Trait(ref t) => { Some(t.to_poly_trait_ref()) } Predicate::Projection(..) | Predicate::Equate(..) | Predicate::Subtype(..) | Predicate::RegionOutlives(..) | Predicate::WellFormed(..) | Predicate::ObjectSafe(..) | Predicate::ClosureKind(..) | Predicate::TypeOutlives(..) => { 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 a `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)] pub struct InstantiatedPredicates<'tcx> { pub predicates: Vec>, } impl<'tcx> InstantiatedPredicates<'tcx> { pub fn empty() -> InstantiatedPredicates<'tcx> { InstantiatedPredicates { predicates: vec![] } } pub fn is_empty(&self) -> bool { self.predicates.is_empty() } } /// 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, Debug, PartialEq, Eq, Hash)] pub struct ParamEnv<'tcx> { /// Obligations that the caller must satisfy. This is basically /// the set of bounds on the in-scope type parameters, translated /// into Obligations, and elaborated and normalized. pub caller_bounds: &'tcx Slice>, /// Typically, this is `Reveal::UserFacing`, but during trans we /// want `Reveal::All` -- note that this is always paired with an /// empty environment. To get that, use `ParamEnv::reveal()`. pub reveal: traits::Reveal, } impl<'tcx> ParamEnv<'tcx> { /// Creates a suitable environment in which to perform trait /// queries on the given value. This will either be `self` *or* /// the empty environment, depending on whether `value` references /// type parameters that are in scope. (If it doesn't, then any /// judgements should be completely independent of the context, /// and hence we can safely use the empty environment so as to /// enable more sharing across functions.) /// /// NB: This is a mildly dubious thing to do, in that a function /// (or other environment) might have wacky where-clauses like /// `where Box: Copy`, which are clearly never /// satisfiable. The code will at present ignore these, /// effectively, when type-checking the body of said /// function. This preserves existing behavior in any /// case. --nmatsakis pub fn and>(self, value: T) -> ParamEnvAnd<'tcx, T> { assert!(!value.needs_infer()); if value.has_param_types() || value.has_self_ty() { ParamEnvAnd { param_env: self, value, } } else { ParamEnvAnd { param_env: ParamEnv::empty(self.reveal), value, } } } } #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)] 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) } } #[derive(Copy, Clone, Debug)] pub struct Destructor { /// The def-id of the destructor method pub did: DefId, } bitflags! { flags AdtFlags: u32 { const NO_ADT_FLAGS = 0, const IS_ENUM = 1 << 0, const IS_PHANTOM_DATA = 1 << 1, const IS_FUNDAMENTAL = 1 << 2, const IS_UNION = 1 << 3, const IS_BOX = 1 << 4, } } #[derive(Debug)] pub struct VariantDef { /// The variant's DefId. If this is a tuple-like struct, /// this is the DefId of the struct's ctor. pub did: DefId, pub name: Name, // struct's name if this is a struct pub discr: VariantDiscr, pub fields: Vec, pub ctor_kind: CtorKind, } #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable)] 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(usize), } #[derive(Debug)] pub struct FieldDef { pub did: DefId, pub name: Name, pub vis: Visibility, } /// The definition of an abstract data type - a struct or enum. /// /// These are all interned (by intern_adt_def) into the adt_defs /// table. pub struct AdtDef { pub did: DefId, pub variants: Vec, flags: AdtFlags, pub repr: ReprOptions, } impl PartialEq for AdtDef { // AdtDef are always interned and this is part of TyS equality #[inline] fn eq(&self, other: &Self) -> bool { self as *const _ == other as *const _ } } impl Eq for AdtDef {} impl Hash for AdtDef { #[inline] fn hash(&self, s: &mut H) { (self as *const AdtDef).hash(s) } } impl<'tcx> serialize::UseSpecializedEncodable for &'tcx AdtDef { fn default_encode(&self, s: &mut S) -> Result<(), S::Error> { self.did.encode(s) } } impl<'tcx> serialize::UseSpecializedDecodable for &'tcx AdtDef {} impl<'a, 'gcx, 'tcx> HashStable> for AdtDef { fn hash_stable(&self, hcx: &mut StableHashingContext<'a, 'gcx, 'tcx>, hasher: &mut StableHasher) { let ty::AdtDef { did, ref variants, ref flags, ref repr, } = *self; did.hash_stable(hcx, hasher); variants.hash_stable(hcx, hasher); flags.hash_stable(hcx, hasher); repr.hash_stable(hcx, hasher); } } #[derive(Copy, Clone, Debug, Eq, PartialEq)] pub enum AdtKind { Struct, Union, Enum } bitflags! { #[derive(RustcEncodable, RustcDecodable, Default)] flags ReprFlags: u8 { const IS_C = 1 << 0, const IS_PACKED = 1 << 1, const IS_SIMD = 1 << 2, // Internal only for now. If true, don't reorder fields. const IS_LINEAR = 1 << 3, // Any of these flags being set prevent field reordering optimisation. const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits | ReprFlags::IS_PACKED.bits | ReprFlags::IS_SIMD.bits | ReprFlags::IS_LINEAR.bits, } } impl_stable_hash_for!(struct ReprFlags { bits }); /// Represents the repr options provided by the user, #[derive(Copy, Clone, Eq, PartialEq, RustcEncodable, RustcDecodable, Default)] pub struct ReprOptions { pub int: Option, pub align: u32, pub flags: ReprFlags, } impl_stable_hash_for!(struct ReprOptions { align, int, flags }); impl ReprOptions { pub fn new(tcx: TyCtxt, did: DefId) -> ReprOptions { let mut flags = ReprFlags::empty(); let mut size = None; let mut max_align = 0; for attr in tcx.get_attrs(did).iter() { for r in attr::find_repr_attrs(tcx.sess.diagnostic(), attr) { flags.insert(match r { attr::ReprExtern => ReprFlags::IS_C, attr::ReprPacked => ReprFlags::IS_PACKED, attr::ReprSimd => ReprFlags::IS_SIMD, attr::ReprInt(i) => { size = Some(i); ReprFlags::empty() }, attr::ReprAlign(align) => { max_align = cmp::max(align, max_align); ReprFlags::empty() }, }); } } // FIXME(eddyb) This is deprecated and should be removed. if tcx.has_attr(did, "simd") { flags.insert(ReprFlags::IS_SIMD); } // This is here instead of layout because the choice must make it into metadata. if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.item_path_str(did))) { flags.insert(ReprFlags::IS_LINEAR); } ReprOptions { int: size, align: max_align, flags: flags } } #[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.flags.contains(ReprFlags::IS_PACKED) } #[inline] pub fn linear(&self) -> bool { self.flags.contains(ReprFlags::IS_LINEAR) } pub fn discr_type(&self) -> attr::IntType { self.int.unwrap_or(attr::SignedInt(ast::IntTy::Is)) } /// 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() } } impl<'a, 'gcx, 'tcx> AdtDef { fn new(tcx: TyCtxt, did: DefId, kind: AdtKind, variants: Vec, repr: ReprOptions) -> Self { let mut flags = AdtFlags::NO_ADT_FLAGS; let attrs = tcx.get_attrs(did); if attr::contains_name(&attrs, "fundamental") { flags = flags | AdtFlags::IS_FUNDAMENTAL; } if Some(did) == tcx.lang_items.phantom_data() { flags = flags | AdtFlags::IS_PHANTOM_DATA; } if Some(did) == tcx.lang_items.owned_box() { flags = flags | AdtFlags::IS_BOX; } match kind { AdtKind::Enum => flags = flags | AdtFlags::IS_ENUM, AdtKind::Union => flags = flags | AdtFlags::IS_UNION, AdtKind::Struct => {} } AdtDef { did, variants, flags, repr, } } #[inline] pub fn is_struct(&self) -> bool { !self.is_union() && !self.is_enum() } #[inline] pub fn is_union(&self) -> bool { self.flags.intersects(AdtFlags::IS_UNION) } #[inline] pub fn is_enum(&self) -> bool { self.flags.intersects(AdtFlags::IS_ENUM) } /// Returns the kind of the ADT - Struct or Enum. #[inline] pub fn adt_kind(&self) -> AdtKind { if self.is_enum() { AdtKind::Enum } else if self.is_union() { AdtKind::Union } else { AdtKind::Struct } } pub fn descr(&self) -> &'static str { match self.adt_kind() { AdtKind::Struct => "struct", AdtKind::Union => "union", AdtKind::Enum => "enum", } } pub fn variant_descr(&self) -> &'static str { match self.adt_kind() { AdtKind::Struct => "struct", AdtKind::Union => "union", AdtKind::Enum => "variant", } } /// Returns whether this type is #[fundamental] for the purposes /// of coherence checking. #[inline] pub fn is_fundamental(&self) -> bool { self.flags.intersects(AdtFlags::IS_FUNDAMENTAL) } /// Returns true if this is PhantomData. #[inline] pub fn is_phantom_data(&self) -> bool { self.flags.intersects(AdtFlags::IS_PHANTOM_DATA) } /// Returns true if this is Box. #[inline] pub fn is_box(&self) -> bool { self.flags.intersects(AdtFlags::IS_BOX) } /// Returns whether this type has a destructor. pub fn has_dtor(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool { self.destructor(tcx).is_some() } /// Asserts this is a struct and returns the struct's unique /// variant. pub fn struct_variant(&self) -> &VariantDef { assert!(!self.is_enum()); &self.variants[0] } #[inline] pub fn predicates(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> GenericPredicates<'gcx> { tcx.predicates_of(self.did) } /// Returns an iterator over all fields contained /// by this ADT. #[inline] pub fn all_fields<'s>(&'s self) -> impl Iterator { self.variants.iter().flat_map(|v| v.fields.iter()) } #[inline] pub fn is_univariant(&self) -> bool { self.variants.len() == 1 } pub fn is_payloadfree(&self) -> bool { !self.variants.is_empty() && self.variants.iter().all(|v| v.fields.is_empty()) } pub fn variant_with_id(&self, vid: DefId) -> &VariantDef { self.variants .iter() .find(|v| v.did == vid) .expect("variant_with_id: unknown variant") } pub fn variant_index_with_id(&self, vid: DefId) -> usize { self.variants .iter() .position(|v| v.did == vid) .expect("variant_index_with_id: unknown variant") } pub fn variant_of_def(&self, def: Def) -> &VariantDef { match def { Def::Variant(vid) | Def::VariantCtor(vid, ..) => self.variant_with_id(vid), Def::Struct(..) | Def::StructCtor(..) | Def::Union(..) | Def::TyAlias(..) | Def::AssociatedTy(..) | Def::SelfTy(..) => self.struct_variant(), _ => bug!("unexpected def {:?} in variant_of_def", def) } } #[inline] pub fn discriminants(&'a self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> impl Iterator + 'a { let param_env = ParamEnv::empty(traits::Reveal::UserFacing); let repr_type = self.repr.discr_type(); let initial = repr_type.initial_discriminant(tcx.global_tcx()); let mut prev_discr = None::; self.variants.iter().map(move |v| { let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr()); if let VariantDiscr::Explicit(expr_did) = v.discr { let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did); match tcx.const_eval(param_env.and((expr_did, substs))) { Ok(ConstVal::Integral(v)) => { discr = v; } err => { if !expr_did.is_local() { span_bug!(tcx.def_span(expr_did), "variant discriminant evaluation succeeded \ in its crate but failed locally: {:?}", err); } } } } prev_discr = Some(discr); discr }) } /// Compute the discriminant value used by a specific variant. /// Unlike `discriminants`, this is (amortized) constant-time, /// only doing at most one query for evaluating an explicit /// discriminant (the last one before the requested variant), /// assuming there are no constant-evaluation errors there. pub fn discriminant_for_variant(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, variant_index: usize) -> ConstInt { let param_env = ParamEnv::empty(traits::Reveal::UserFacing); let repr_type = self.repr.discr_type(); let mut explicit_value = repr_type.initial_discriminant(tcx.global_tcx()); let mut explicit_index = variant_index; loop { match self.variants[explicit_index].discr { ty::VariantDiscr::Relative(0) => break, ty::VariantDiscr::Relative(distance) => { explicit_index -= distance; } ty::VariantDiscr::Explicit(expr_did) => { let substs = Substs::identity_for_item(tcx.global_tcx(), expr_did); match tcx.const_eval(param_env.and((expr_did, substs))) { Ok(ConstVal::Integral(v)) => { explicit_value = v; break; } err => { if !expr_did.is_local() { span_bug!(tcx.def_span(expr_did), "variant discriminant evaluation succeeded \ in its crate but failed locally: {:?}", err); } if explicit_index == 0 { break; } explicit_index -= 1; } } } } } let discr = explicit_value.to_u128_unchecked() .wrapping_add((variant_index - explicit_index) as u128); match repr_type { attr::UnsignedInt(ty) => { ConstInt::new_unsigned_truncating(discr, ty, tcx.sess.target.uint_type) } attr::SignedInt(ty) => { ConstInt::new_signed_truncating(discr as i128, ty, tcx.sess.target.int_type) } } } pub fn destructor(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Option { tcx.adt_destructor(self.did) } /// Returns a list of types such that `Self: Sized` if and only /// if that type is Sized, or `TyErr` if this type is recursive. /// /// Oddly enough, checking that the sized-constraint is Sized is /// actually more expressive than checking all members: /// the Sized trait is inductive, so an associated type that references /// Self would prevent its containing ADT from being Sized. /// /// Due to normalization being eager, this applies even if /// the associated type is behind a pointer, e.g. issue #31299. pub fn sized_constraint(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> &'tcx [Ty<'tcx>] { match queries::adt_sized_constraint::try_get(tcx, DUMMY_SP, self.did) { Ok(tys) => tys, Err(_) => { debug!("adt_sized_constraint: {:?} is recursive", self); // This should be reported as an error by `check_representable`. // // Consider the type as Sized in the meanwhile to avoid // further errors. tcx.intern_type_list(&[tcx.types.err]) } } } fn sized_constraint_for_ty(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> Vec> { let result = match ty.sty { TyBool | TyChar | TyInt(..) | TyUint(..) | TyFloat(..) | TyRawPtr(..) | TyRef(..) | TyFnDef(..) | TyFnPtr(_) | TyArray(..) | TyClosure(..) | TyNever => { vec![] } TyStr | TyDynamic(..) | TySlice(_) | TyError => { // these are never sized - return the target type vec![ty] } TyTuple(ref tys, _) => { match tys.last() { None => vec![], Some(ty) => self.sized_constraint_for_ty(tcx, ty) } } TyAdt(adt, substs) => { // recursive case let adt_tys = adt.sized_constraint(tcx); debug!("sized_constraint_for_ty({:?}) intermediate = {:?}", ty, adt_tys); adt_tys.iter() .map(|ty| ty.subst(tcx, substs)) .flat_map(|ty| self.sized_constraint_for_ty(tcx, ty)) .collect() } TyProjection(..) | TyAnon(..) => { // must calculate explicitly. // FIXME: consider special-casing always-Sized projections vec![ty] } TyParam(..) => { // perf hack: if there is a `T: Sized` bound, then // we know that `T` is Sized and do not need to check // it on the impl. let sized_trait = match tcx.lang_items.sized_trait() { Some(x) => x, _ => return vec![ty] }; let sized_predicate = Binder(TraitRef { def_id: sized_trait, substs: tcx.mk_substs_trait(ty, &[]) }).to_predicate(); let predicates = tcx.predicates_of(self.did).predicates; if predicates.into_iter().any(|p| p == sized_predicate) { vec![] } else { vec![ty] } } TyInfer(..) => { bug!("unexpected type `{:?}` in sized_constraint_for_ty", ty) } }; debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result); result } } impl<'a, 'gcx, 'tcx> VariantDef { #[inline] pub fn find_field_named(&self, name: ast::Name) -> Option<&FieldDef> { self.index_of_field_named(name).map(|index| &self.fields[index]) } pub fn index_of_field_named(&self, name: ast::Name) -> Option { if let Some(index) = self.fields.iter().position(|f| f.name == name) { return Some(index); } let mut ident = name.to_ident(); while ident.ctxt != SyntaxContext::empty() { ident.ctxt.remove_mark(); if let Some(field) = self.fields.iter().position(|f| f.name.to_ident() == ident) { return Some(field); } } None } #[inline] pub fn field_named(&self, name: ast::Name) -> &FieldDef { self.find_field_named(name).unwrap() } } impl<'a, 'gcx, 'tcx> FieldDef { pub fn ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, subst: &Substs<'tcx>) -> Ty<'tcx> { tcx.type_of(self.did).subst(tcx, subst) } } #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)] pub enum ClosureKind { // Warning: Ordering is significant here! The ordering is chosen // because the trait Fn is a subtrait of FnMut and so in turn, and // hence we order it so that Fn < FnMut < FnOnce. Fn, FnMut, FnOnce, } impl<'a, 'tcx> ClosureKind { pub fn trait_did(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>) -> DefId { match *self { ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem), ClosureKind::FnMut => { tcx.require_lang_item(FnMutTraitLangItem) } ClosureKind::FnOnce => { tcx.require_lang_item(FnOnceTraitLangItem) } } } /// True if this a type that impls this closure kind /// must also implement `other`. pub fn extends(self, other: ty::ClosureKind) -> bool { match (self, other) { (ClosureKind::Fn, ClosureKind::Fn) => true, (ClosureKind::Fn, ClosureKind::FnMut) => true, (ClosureKind::Fn, ClosureKind::FnOnce) => true, (ClosureKind::FnMut, ClosureKind::FnMut) => true, (ClosureKind::FnMut, ClosureKind::FnOnce) => true, (ClosureKind::FnOnce, ClosureKind::FnOnce) => true, _ => false, } } } impl<'tcx> TyS<'tcx> { /// Iterator that walks `self` and any types reachable from /// `self`, in depth-first order. Note that just walks the types /// that appear in `self`, it does not descend into the fields of /// structs or variants. For example: /// /// ```notrust /// isize => { isize } /// Foo> => { Foo>, Bar, isize } /// [isize] => { [isize], isize } /// ``` pub fn walk(&'tcx self) -> TypeWalker<'tcx> { TypeWalker::new(self) } /// Iterator that walks the immediate children of `self`. Hence /// `Foo, u32>` yields the sequence `[Bar, u32]` /// (but not `i32`, like `walk`). pub fn walk_shallow(&'tcx self) -> AccIntoIter> { walk::walk_shallow(self) } /// Walks `ty` and any types appearing within `ty`, invoking the /// callback `f` on each type. If the callback returns false, then the /// children of the current type are ignored. /// /// Note: prefer `ty.walk()` where possible. pub fn maybe_walk(&'tcx self, mut f: F) where F : FnMut(Ty<'tcx>) -> bool { let mut walker = self.walk(); while let Some(ty) = walker.next() { if !f(ty) { walker.skip_current_subtree(); } } } } #[derive(Copy, Clone, Debug, PartialEq, Eq)] pub enum LvaluePreference { PreferMutLvalue, NoPreference } impl LvaluePreference { pub fn from_mutbl(m: hir::Mutability) -> Self { match m { hir::MutMutable => PreferMutLvalue, hir::MutImmutable => NoPreference, } } } impl BorrowKind { pub fn from_mutbl(m: hir::Mutability) -> BorrowKind { match m { hir::MutMutable => MutBorrow, hir::MutImmutable => ImmBorrow, } } /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a /// mutability that is stronger than necessary so that it at least *would permit* the borrow in /// question. pub fn to_mutbl_lossy(self) -> hir::Mutability { match self { MutBorrow => hir::MutMutable, ImmBorrow => hir::MutImmutable, // We have no type corresponding to a unique imm borrow, so // use `&mut`. It gives all the capabilities of an `&uniq` // and hence is a safe "over approximation". UniqueImmBorrow => hir::MutMutable, } } pub fn to_user_str(&self) -> &'static str { match *self { MutBorrow => "mutable", ImmBorrow => "immutable", UniqueImmBorrow => "uniquely immutable", } } } #[derive(Debug, Clone)] pub enum Attributes<'gcx> { Owned(Rc<[ast::Attribute]>), Borrowed(&'gcx [ast::Attribute]) } impl<'gcx> ::std::ops::Deref for Attributes<'gcx> { type Target = [ast::Attribute]; fn deref(&self) -> &[ast::Attribute] { match self { &Attributes::Owned(ref data) => &data, &Attributes::Borrowed(data) => data } } } impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { pub fn body_tables(self, body: hir::BodyId) -> &'gcx TypeckTables<'gcx> { self.typeck_tables_of(self.hir.body_owner_def_id(body)) } /// Returns an iterator of the def-ids for all body-owners in this /// crate. If you would prefer to iterate over the bodies /// themselves, you can do `self.hir.krate().body_ids.iter()`. pub fn body_owners(self) -> impl Iterator + 'a { self.hir.krate() .body_ids .iter() .map(move |&body_id| self.hir.body_owner_def_id(body_id)) } pub fn expr_span(self, id: NodeId) -> Span { match self.hir.find(id) { Some(hir_map::NodeExpr(e)) => { e.span } Some(f) => { bug!("Node id {} is not an expr: {:?}", id, f); } None => { bug!("Node id {} is not present in the node map", id); } } } pub fn local_var_name_str(self, id: NodeId) -> InternedString { match self.hir.find(id) { Some(hir_map::NodeLocal(pat)) => { match pat.node { hir::PatKind::Binding(_, _, ref path1, _) => path1.node.as_str(), _ => { bug!("Variable id {} maps to {:?}, not local", id, pat); }, } }, r => bug!("Variable id {} maps to {:?}, not local", id, r), } } pub fn expr_is_lval(self, expr: &hir::Expr) -> bool { match expr.node { hir::ExprPath(hir::QPath::Resolved(_, ref path)) => { match path.def { Def::Local(..) | Def::Upvar(..) | Def::Static(..) | Def::Err => true, _ => false, } } hir::ExprType(ref e, _) => { self.expr_is_lval(e) } hir::ExprUnary(hir::UnDeref, _) | hir::ExprField(..) | hir::ExprTupField(..) | hir::ExprIndex(..) => { true } // Partially qualified paths in expressions can only legally // refer to associated items which are always rvalues. hir::ExprPath(hir::QPath::TypeRelative(..)) | hir::ExprCall(..) | hir::ExprMethodCall(..) | hir::ExprStruct(..) | hir::ExprTup(..) | hir::ExprIf(..) | hir::ExprMatch(..) | hir::ExprClosure(..) | hir::ExprBlock(..) | hir::ExprRepeat(..) | hir::ExprArray(..) | hir::ExprBreak(..) | hir::ExprAgain(..) | hir::ExprRet(..) | hir::ExprWhile(..) | hir::ExprLoop(..) | hir::ExprAssign(..) | hir::ExprInlineAsm(..) | hir::ExprAssignOp(..) | hir::ExprLit(_) | hir::ExprUnary(..) | hir::ExprBox(..) | hir::ExprAddrOf(..) | hir::ExprBinary(..) | hir::ExprCast(..) => { false } } } pub fn provided_trait_methods(self, id: DefId) -> Vec { self.associated_items(id) .filter(|item| item.kind == AssociatedKind::Method && item.defaultness.has_value()) .collect() } pub fn trait_relevant_for_never(self, did: DefId) -> bool { self.associated_items(did).any(|item| { item.relevant_for_never() }) } pub fn opt_associated_item(self, def_id: DefId) -> Option { let is_associated_item = if let Some(node_id) = self.hir.as_local_node_id(def_id) { match self.hir.get(node_id) { hir_map::NodeTraitItem(_) | hir_map::NodeImplItem(_) => true, _ => false, } } else { match self.describe_def(def_id).expect("no def for def-id") { Def::AssociatedConst(_) | Def::Method(_) | Def::AssociatedTy(_) => true, _ => false, } }; if is_associated_item { Some(self.associated_item(def_id)) } else { None } } fn associated_item_from_trait_item_ref(self, parent_def_id: DefId, parent_vis: &hir::Visibility, trait_item_ref: &hir::TraitItemRef) -> AssociatedItem { let def_id = self.hir.local_def_id(trait_item_ref.id.node_id); let (kind, has_self) = match trait_item_ref.kind { hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false), hir::AssociatedItemKind::Method { has_self } => { (ty::AssociatedKind::Method, has_self) } hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false), }; AssociatedItem { name: trait_item_ref.name, kind, // Visibility of trait items is inherited from their traits. vis: Visibility::from_hir(parent_vis, trait_item_ref.id.node_id, self), defaultness: trait_item_ref.defaultness, def_id, container: TraitContainer(parent_def_id), method_has_self_argument: has_self } } fn associated_item_from_impl_item_ref(self, parent_def_id: DefId, impl_item_ref: &hir::ImplItemRef) -> AssociatedItem { let def_id = self.hir.local_def_id(impl_item_ref.id.node_id); let (kind, has_self) = match impl_item_ref.kind { hir::AssociatedItemKind::Const => (ty::AssociatedKind::Const, false), hir::AssociatedItemKind::Method { has_self } => { (ty::AssociatedKind::Method, has_self) } hir::AssociatedItemKind::Type => (ty::AssociatedKind::Type, false), }; ty::AssociatedItem { name: impl_item_ref.name, kind, // Visibility of trait impl items doesn't matter. vis: ty::Visibility::from_hir(&impl_item_ref.vis, impl_item_ref.id.node_id, self), defaultness: impl_item_ref.defaultness, def_id, container: ImplContainer(parent_def_id), method_has_self_argument: has_self } } #[inline] // FIXME(#35870) Avoid closures being unexported due to impl Trait. pub fn associated_items(self, def_id: DefId) -> impl Iterator + 'a { let def_ids = self.associated_item_def_ids(def_id); (0..def_ids.len()).map(move |i| self.associated_item(def_ids[i])) } /// Returns true if the impls are the same polarity and are implementing /// a trait which contains no items pub fn impls_are_allowed_to_overlap(self, def_id1: DefId, def_id2: DefId) -> bool { if !self.sess.features.borrow().overlapping_marker_traits { return false; } let trait1_is_empty = self.impl_trait_ref(def_id1) .map_or(false, |trait_ref| { self.associated_item_def_ids(trait_ref.def_id).is_empty() }); let trait2_is_empty = self.impl_trait_ref(def_id2) .map_or(false, |trait_ref| { self.associated_item_def_ids(trait_ref.def_id).is_empty() }); self.impl_polarity(def_id1) == self.impl_polarity(def_id2) && trait1_is_empty && trait2_is_empty } // Returns `ty::VariantDef` if `def` refers to a struct, // or variant or their constructors, panics otherwise. pub fn expect_variant_def(self, def: Def) -> &'tcx VariantDef { match def { Def::Variant(did) | Def::VariantCtor(did, ..) => { let enum_did = self.parent_def_id(did).unwrap(); self.adt_def(enum_did).variant_with_id(did) } Def::Struct(did) | Def::Union(did) => { self.adt_def(did).struct_variant() } Def::StructCtor(ctor_did, ..) => { let did = self.parent_def_id(ctor_did).expect("struct ctor has no parent"); self.adt_def(did).struct_variant() } _ => bug!("expect_variant_def used with unexpected def {:?}", def) } } pub fn def_key(self, id: DefId) -> hir_map::DefKey { if id.is_local() { self.hir.def_key(id) } else { self.sess.cstore.def_key(id) } } /// Convert a `DefId` into its fully expanded `DefPath` (every /// `DefId` is really just an interned def-path). /// /// Note that if `id` is not local to this crate, the result will /// be a non-local `DefPath`. pub fn def_path(self, id: DefId) -> hir_map::DefPath { if id.is_local() { self.hir.def_path(id) } else { self.sess.cstore.def_path(id) } } #[inline] pub fn def_path_hash(self, def_id: DefId) -> hir_map::DefPathHash { if def_id.is_local() { self.hir.definitions().def_path_hash(def_id.index) } else { self.sess.cstore.def_path_hash(def_id) } } pub fn item_name(self, id: DefId) -> ast::Name { if let Some(id) = self.hir.as_local_node_id(id) { self.hir.name(id) } else if id.index == CRATE_DEF_INDEX { self.sess.cstore.original_crate_name(id.krate) } else { let def_key = self.sess.cstore.def_key(id); // The name of a StructCtor is that of its struct parent. if let hir_map::DefPathData::StructCtor = def_key.disambiguated_data.data { self.item_name(DefId { krate: id.krate, index: def_key.parent.unwrap() }) } else { def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| { bug!("item_name: no name for {:?}", self.def_path(id)); }) } } } /// Return the possibly-auto-generated MIR of a (DefId, Subst) pair. pub fn instance_mir(self, instance: ty::InstanceDef<'gcx>) -> &'gcx Mir<'gcx> { match instance { ty::InstanceDef::Item(did) => { self.optimized_mir(did) } ty::InstanceDef::Intrinsic(..) | ty::InstanceDef::FnPtrShim(..) | ty::InstanceDef::Virtual(..) | ty::InstanceDef::ClosureOnceShim { .. } | ty::InstanceDef::DropGlue(..) => { self.mir_shims(instance) } } } /// Given the DefId of an item, returns its MIR, borrowed immutably. /// Returns None if there is no MIR for the DefId pub fn maybe_optimized_mir(self, did: DefId) -> Option<&'gcx Mir<'gcx>> { if self.is_mir_available(did) { Some(self.optimized_mir(did)) } else { None } } /// Get the attributes of a definition. pub fn get_attrs(self, did: DefId) -> Attributes<'gcx> { if let Some(id) = self.hir.as_local_node_id(did) { Attributes::Borrowed(self.hir.attrs(id)) } else { Attributes::Owned(self.item_attrs(did)) } } /// Determine whether an item is annotated with an attribute pub fn has_attr(self, did: DefId, attr: &str) -> bool { self.get_attrs(did).iter().any(|item| item.check_name(attr)) } pub fn trait_has_default_impl(self, trait_def_id: DefId) -> bool { self.trait_def(trait_def_id).has_default_impl } /// Given the def_id of an impl, return the def_id of the trait it implements. /// If it implements no trait, return `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 def ID describes a method belonging to an impl, return the /// ID of the impl that the method belongs to. Otherwise, return `None`. pub fn impl_of_method(self, def_id: DefId) -> Option { let item = if def_id.krate != LOCAL_CRATE { if let Some(Def::Method(_)) = self.describe_def(def_id) { Some(self.associated_item(def_id)) } else { None } } else { self.opt_associated_item(def_id) }; match item { Some(trait_item) => { match trait_item.container { TraitContainer(_) => None, ImplContainer(def_id) => Some(def_id), } } None => None } } pub fn node_scope_region(self, id: NodeId) -> Region<'tcx> { self.mk_region(ty::ReScope(CodeExtent::Misc(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 impl_did.is_local() { let node_id = self.hir.as_local_node_id(impl_did).unwrap(); Ok(self.hir.span(node_id)) } else { Err(self.sess.cstore.crate_name(impl_did.krate)) } } pub fn adjust(self, name: Name, scope: DefId, block: NodeId) -> (Ident, DefId) { self.adjust_ident(name.to_ident(), scope, block) } pub fn adjust_ident(self, mut ident: Ident, scope: DefId, block: NodeId) -> (Ident, DefId) { let expansion = match scope.krate { LOCAL_CRATE => self.hir.definitions().expansion(scope.index), _ => Mark::root(), }; let scope = match ident.ctxt.adjust(expansion) { Some(macro_def) => self.hir.definitions().macro_def_scope(macro_def), None => self.hir.get_module_parent(block), }; (ident, scope) } } impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> { pub fn with_freevars(self, fid: NodeId, f: F) -> T where F: FnOnce(&[hir::Freevar]) -> T, { match self.freevars.borrow().get(&fid) { None => f(&[]), Some(d) => f(&d[..]) } } } fn associated_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> AssociatedItem { let id = tcx.hir.as_local_node_id(def_id).unwrap(); let parent_id = tcx.hir.get_parent(id); let parent_def_id = tcx.hir.local_def_id(parent_id); let parent_item = tcx.hir.expect_item(parent_id); match parent_item.node { hir::ItemImpl(.., ref impl_item_refs) => { if let Some(impl_item_ref) = impl_item_refs.iter().find(|i| i.id.node_id == id) { let assoc_item = tcx.associated_item_from_impl_item_ref(parent_def_id, impl_item_ref); debug_assert_eq!(assoc_item.def_id, def_id); return assoc_item; } } hir::ItemTrait(.., ref trait_item_refs) => { if let Some(trait_item_ref) = trait_item_refs.iter().find(|i| i.id.node_id == id) { let assoc_item = tcx.associated_item_from_trait_item_ref(parent_def_id, &parent_item.vis, trait_item_ref); debug_assert_eq!(assoc_item.def_id, def_id); return assoc_item; } } _ => { } } span_bug!(parent_item.span, "unexpected parent of trait or impl item or item not found: {:?}", parent_item.node) } /// Calculates the Sized-constraint. /// /// In fact, there are only a few options for the types in the constraint: /// - an obviously-unsized type /// - a type parameter or projection whose Sizedness can't be known /// - a tuple of type parameters or projections, if there are multiple /// such. /// - a TyError, if a type contained itself. The representability /// check should catch this case. fn adt_sized_constraint<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> &'tcx [Ty<'tcx>] { let def = tcx.adt_def(def_id); let result = tcx.intern_type_list(&def.variants.iter().flat_map(|v| { v.fields.last() }).flat_map(|f| { def.sized_constraint_for_ty(tcx, tcx.type_of(f.did)) }).collect::>()); debug!("adt_sized_constraint: {:?} => {:?}", def, result); result } /// Calculates the dtorck constraint for a type. fn adt_dtorck_constraint<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> DtorckConstraint<'tcx> { let def = tcx.adt_def(def_id); let span = tcx.def_span(def_id); debug!("dtorck_constraint: {:?}", def); if def.is_phantom_data() { let result = DtorckConstraint { outlives: vec![], dtorck_types: vec![ tcx.mk_param_from_def(&tcx.generics_of(def_id).types[0]) ] }; debug!("dtorck_constraint: {:?} => {:?}", def, result); return result; } let mut result = def.all_fields() .map(|field| tcx.type_of(field.did)) .map(|fty| tcx.dtorck_constraint_for_ty(span, fty, 0, fty)) .collect::>() .unwrap_or(DtorckConstraint::empty()); result.outlives.extend(tcx.destructor_constraints(def)); result.dedup(); debug!("dtorck_constraint: {:?} => {:?}", def, result); result } fn associated_item_def_ids<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Rc> { let id = tcx.hir.as_local_node_id(def_id).unwrap(); let item = tcx.hir.expect_item(id); let vec: Vec<_> = match item.node { hir::ItemTrait(.., ref trait_item_refs) => { trait_item_refs.iter() .map(|trait_item_ref| trait_item_ref.id) .map(|id| tcx.hir.local_def_id(id.node_id)) .collect() } hir::ItemImpl(.., ref impl_item_refs) => { impl_item_refs.iter() .map(|impl_item_ref| impl_item_ref.id) .map(|id| tcx.hir.local_def_id(id.node_id)) .collect() } _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait") }; Rc::new(vec) } fn def_span<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Span { tcx.hir.span_if_local(def_id).unwrap() } /// If the given def ID describes an item belonging to a trait, /// return the ID of the trait that the trait item belongs to. /// Otherwise, return `None`. fn trait_of_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Option { tcx.opt_associated_item(def_id) .and_then(|associated_item| { match associated_item.container { TraitContainer(def_id) => Some(def_id), ImplContainer(_) => None } }) } /// See `ParamEnv` struct def'n for details. fn param_env<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> ParamEnv<'tcx> { // Compute the bounds on Self and the type parameters. let bounds = tcx.predicates_of(def_id).instantiate_identity(tcx); let predicates = bounds.predicates; // Finally, we have to normalize the bounds in the environment, in // case they contain any associated type projections. This process // can yield errors if the put in illegal associated types, like // `::Bar` where `i32` does not implement `Foo`. We // report these errors right here; this doesn't actually feel // right to me, because constructing the environment feels like a // kind of a "idempotent" action, but I'm not sure where would be // a better place. In practice, we construct environments for // every fn once during type checking, and we'll abort if there // are any errors at that point, so after type checking you can be // sure that this will succeed without errors anyway. let unnormalized_env = ty::ParamEnv::new(tcx.intern_predicates(&predicates), traits::Reveal::UserFacing); let body_id = tcx.hir.as_local_node_id(def_id).map_or(DUMMY_NODE_ID, |id| { tcx.hir.maybe_body_owned_by(id).map_or(id, |body| body.node_id) }); let cause = traits::ObligationCause::misc(tcx.def_span(def_id), body_id); traits::normalize_param_env_or_error(tcx, def_id, unnormalized_env, cause) } pub fn provide(providers: &mut ty::maps::Providers) { util::provide(providers); *providers = ty::maps::Providers { associated_item, associated_item_def_ids, adt_sized_constraint, adt_dtorck_constraint, def_span, param_env, trait_of_item, trait_impls_of: trait_def::trait_impls_of_provider, relevant_trait_impls_for: trait_def::relevant_trait_impls_provider, ..*providers }; } pub fn provide_extern(providers: &mut ty::maps::Providers) { *providers = ty::maps::Providers { adt_sized_constraint, adt_dtorck_constraint, trait_impls_of: trait_def::trait_impls_of_provider, relevant_trait_impls_for: trait_def::relevant_trait_impls_provider, param_env, ..*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)] pub struct CrateInherentImpls { pub inherent_impls: DefIdMap>>, } /// A set of constraints that need to be satisfied in order for /// a type to be valid for destruction. #[derive(Clone, Debug)] pub struct DtorckConstraint<'tcx> { /// Types that are required to be alive in order for this /// type to be valid for destruction. pub outlives: Vec>, /// Types that could not be resolved: projections and params. pub dtorck_types: Vec>, } impl<'tcx> FromIterator> for DtorckConstraint<'tcx> { fn from_iter>>(iter: I) -> Self { let mut result = Self::empty(); for constraint in iter { result.outlives.extend(constraint.outlives); result.dtorck_types.extend(constraint.dtorck_types); } result } } impl<'tcx> DtorckConstraint<'tcx> { fn empty() -> DtorckConstraint<'tcx> { DtorckConstraint { outlives: vec![], dtorck_types: vec![] } } fn dedup<'a>(&mut self) { let mut outlives = FxHashSet(); let mut dtorck_types = FxHashSet(); self.outlives.retain(|&val| outlives.replace(val).is_none()); self.dtorck_types.retain(|&val| dtorck_types.replace(val).is_none()); } } #[derive(Clone, PartialEq, Eq, PartialOrd, Ord)] pub struct SymbolName { // FIXME: we don't rely on interning or equality here - better have // this be a `&'tcx str`. pub name: InternedString } impl Deref for SymbolName { type Target = str; fn deref(&self) -> &str { &self.name } } impl fmt::Display for SymbolName { fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { fmt::Display::fmt(&self.name, fmt) } }