// ignore-tidy-filelength #![allow(usage_of_ty_tykind)] pub use self::Variance::*; pub use self::AssociatedItemContainer::*; pub use self::BorrowKind::*; pub use self::IntVarValue::*; pub use self::fold::TypeFoldable; use crate::hir::{map as hir_map, UpvarMap, GlobMap, TraitMap}; use crate::hir::Node; use crate::hir::def::{Res, DefKind, CtorOf, CtorKind, ExportMap}; use crate::hir::def_id::{CrateNum, DefId, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE}; use rustc_data_structures::svh::Svh; use rustc_macros::HashStable; use crate::ich::Fingerprint; use crate::ich::StableHashingContext; use crate::infer::canonical::Canonical; use crate::middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem}; use crate::middle::resolve_lifetime::ObjectLifetimeDefault; use crate::mir::Mir; use crate::mir::interpret::{GlobalId, ErrorHandled}; use crate::mir::GeneratorLayout; use crate::session::CrateDisambiguator; use crate::traits::{self, Reveal}; use crate::ty; use crate::ty::layout::VariantIdx; use crate::ty::subst::{Subst, InternalSubsts, SubstsRef}; use crate::ty::util::{IntTypeExt, Discr}; use crate::ty::walk::TypeWalker; use crate::util::captures::Captures; use crate::util::nodemap::{NodeSet, DefIdMap, FxHashMap}; use arena::SyncDroplessArena; use crate::session::DataTypeKind; use serialize::{self, Encodable, Encoder}; use std::cell::RefCell; use std::cmp::{self, Ordering}; use std::fmt; use std::hash::{Hash, Hasher}; use std::ops::Deref; use rustc_data_structures::sync::{self, Lrc, ParallelIterator, par_iter}; use std::slice; use std::{mem, ptr}; use std::ops::Range; use syntax::ast::{self, Name, Ident, NodeId}; use syntax::attr; use syntax::ext::hygiene::Mark; use syntax::symbol::{keywords, Symbol, LocalInternedString, InternedString}; use syntax_pos::Span; use smallvec; use rustc_data_structures::indexed_vec::{Idx, IndexVec}; use rustc_data_structures::stable_hasher::{StableHasher, StableHasherResult, HashStable}; use crate::hir; pub use self::sty::{Binder, BoundTy, BoundTyKind, BoundVar, DebruijnIndex, INNERMOST}; pub use self::sty::{FnSig, GenSig, CanonicalPolyFnSig, PolyFnSig, PolyGenSig}; pub use self::sty::{InferTy, ParamTy, ParamConst, InferConst, ProjectionTy, ExistentialPredicate}; pub use self::sty::{ClosureSubsts, GeneratorSubsts, UpvarSubsts, TypeAndMut}; pub use self::sty::{TraitRef, TyKind, PolyTraitRef}; pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef}; pub use self::sty::{ExistentialProjection, PolyExistentialProjection, Const}; pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region}; pub use self::sty::RegionKind; pub use self::sty::{TyVid, IntVid, FloatVid, ConstVid, RegionVid}; pub use self::sty::BoundRegion::*; pub use self::sty::InferTy::*; pub use self::sty::RegionKind::*; pub use self::sty::TyKind::*; pub use self::binding::BindingMode; pub use self::binding::BindingMode::*; pub use self::context::{TyCtxt, FreeRegionInfo, GlobalArenas, AllArenas, tls, keep_local}; pub use self::context::{Lift, TypeckTables, CtxtInterners, GlobalCtxt}; pub use self::context::{ UserTypeAnnotationIndex, UserType, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, ResolvedOpaqueTy, }; pub use self::instance::{Instance, InstanceDef}; pub use self::trait_def::TraitDef; pub use self::query::queries; pub mod adjustment; pub mod binding; pub mod cast; #[macro_use] pub mod codec; mod constness; pub mod error; mod erase_regions; pub mod fast_reject; pub mod flags; pub mod fold; pub mod inhabitedness; pub mod layout; pub mod _match; pub mod outlives; pub mod print; pub mod query; 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 instance; mod structural_impls; mod sty; // Data types #[derive(Clone)] pub struct Resolutions { pub upvars: UpvarMap, pub trait_map: TraitMap, pub maybe_unused_trait_imports: NodeSet, pub maybe_unused_extern_crates: Vec<(NodeId, Span)>, pub export_map: ExportMap, pub glob_map: GlobMap, /// 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, } #[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable)] pub enum AssociatedItemContainer { TraitContainer(DefId), ImplContainer(DefId), } impl AssociatedItemContainer { /// Asserts that this is the `DefId` of an associated item declared /// in a trait, and returns the trait `DefId`. pub fn assert_trait(&self) -> DefId { match *self { TraitContainer(id) => id, _ => bug!("associated item has wrong container type: {:?}", self) } } 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, HashStable)] pub struct AssociatedItem { pub def_id: DefId, #[stable_hasher(project(name))] pub ident: Ident, 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, HashStable)] pub enum AssociatedKind { Const, Method, Existential, Type } impl AssociatedItem { pub fn def_kind(&self) -> DefKind { match self.kind { AssociatedKind::Const => DefKind::AssociatedConst, AssociatedKind::Method => DefKind::Method, AssociatedKind::Type => DefKind::AssociatedTy, AssociatedKind::Existential => DefKind::AssociatedExistential, } } /// Tests whether the associated item admits a non-trivial implementation /// for ! pub fn relevant_for_never<'tcx>(&self) -> bool { match self.kind { AssociatedKind::Existential | AssociatedKind::Const | 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)`. tcx.fn_sig(self.def_id).skip_binder().to_string() } ty::AssociatedKind::Type => format!("type {};", self.ident), ty::AssociatedKind::Existential => format!("existential type {};", self.ident), ty::AssociatedKind::Const => { format!("const {}: {:?};", self.ident, tcx.type_of(self.def_id)) } } } } #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable, HashStable)] pub enum Visibility { /// Visible everywhere (including in other crates). Public, /// Visible only in the given crate-local module. Restricted(DefId), /// Not visible anywhere in the local crate. This is the visibility of private external items. Invisible, } 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: hir::HirId, tcx: TyCtxt<'_, '_, '_>) -> Self { match visibility.node { hir::VisibilityKind::Public => Visibility::Public, hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)), hir::VisibilityKind::Restricted { ref path, .. } => match path.res { // If there is no resolution, `resolve` will have already reported an error, so // assume that the visibility is public to avoid reporting more privacy errors. Res::Err => Visibility::Public, def => Visibility::Restricted(def.def_id()), }, hir::VisibilityKind::Inherited => { Visibility::Restricted(tcx.hir().get_module_parent_by_hir_id(id)) } } } /// Returns `true` if an item with this visibility is accessible from the given block. pub fn is_accessible_from(self, module: DefId, tree: T) -> bool { let restriction = match self { // Public items are visible everywhere. Visibility::Public => return true, // Private items from other crates are visible nowhere. Visibility::Invisible => return false, // Restricted items are visible in an arbitrary local module. Visibility::Restricted(other) if other.krate != module.krate => return false, Visibility::Restricted(module) => module, }; tree.is_descendant_of(module, restriction) } /// Returns `true` if this visibility is at least as accessible as the given visibility pub fn is_at_least(self, vis: Visibility, tree: T) -> bool { let vis_restriction = match vis { Visibility::Public => return self == Visibility::Public, Visibility::Invisible => return true, Visibility::Restricted(module) => module, }; self.is_accessible_from(vis_restriction, tree) } // Returns `true` if this item is visible anywhere in the local crate. pub fn is_visible_locally(self) -> bool { match self { Visibility::Public => true, Visibility::Restricted(def_id) => def_id.is_local(), Visibility::Invisible => false, } } } #[derive(Copy, Clone, PartialEq, Eq, RustcDecodable, RustcEncodable, Hash, HashStable)] 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. #[derive(HashStable)] pub struct CrateVariancesMap<'tcx> { /// For each item with generics, maps to a vector of the variance /// of its generics. If an item has no generics, it will have no /// entry. pub variances: FxHashMap, } 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! { pub struct 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_PLACEHOLDER = 1 << 4; /// Does this have any `ReEarlyBound` regions? Used to /// determine whether substitition is required, since those /// represent regions that are bound in a `ty::Generics` and /// hence may be substituted. const HAS_RE_EARLY_BOUND = 1 << 5; /// Does this have any region that "appears free" in the type? /// Basically anything but `ReLateBound` and `ReErased`. const HAS_FREE_REGIONS = 1 << 6; /// Is an error type reachable? const HAS_TY_ERR = 1 << 7; const HAS_PROJECTION = 1 << 8; // FIXME: Rename this to the actual property since it's used for generators too 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_FREE_LOCAL_NAMES = 1 << 10; /// Present if the type belongs in a local type context. /// Only set for Infer 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; /// Does this have any `ReLateBound` regions? Used to check /// if a global bound is safe to evaluate. const HAS_RE_LATE_BOUND = 1 << 13; const HAS_TY_PLACEHOLDER = 1 << 14; const HAS_CT_INFER = 1 << 15; const HAS_CT_PLACEHOLDER = 1 << 16; 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_CT_INFER.bits | TypeFlags::HAS_RE_PLACEHOLDER.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_FREE_LOCAL_NAMES.bits | TypeFlags::KEEP_IN_LOCAL_TCX.bits | TypeFlags::HAS_RE_LATE_BOUND.bits | TypeFlags::HAS_TY_PLACEHOLDER.bits | TypeFlags::HAS_CT_PLACEHOLDER.bits; } } pub struct TyS<'tcx> { pub sty: TyKind<'tcx>, pub flags: TypeFlags, /// This is a kind of confusing thing: it stores the smallest /// binder such that /// /// (a) the binder itself captures nothing but /// (b) all the late-bound things within the type are captured /// by some sub-binder. /// /// So, for a type without any late-bound things, like `u32`, this /// will be *innermost*, because that is the innermost binder that /// captures nothing. But for a type `&'D u32`, where `'D` is a /// late-bound region with De Bruijn index `D`, this would be `D + 1` /// -- the binder itself does not capture `D`, but `D` is captured /// by an inner binder. /// /// We call this concept an "exclusive" binder `D` because all /// De Bruijn indices within the type are contained within `0..D` /// (exclusive). outer_exclusive_binder: ty::DebruijnIndex, } // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger. #[cfg(target_arch = "x86_64")] static_assert!(MEM_SIZE_OF_TY_S: ::std::mem::size_of::>() == 32); impl<'tcx> Ord for TyS<'tcx> { fn cmp(&self, other: &TyS<'tcx>) -> Ordering { self.sty.cmp(&other.sty) } } impl<'tcx> PartialOrd for TyS<'tcx> { fn partial_cmp(&self, other: &TyS<'tcx>) -> Option { Some(self.sty.cmp(&other.sty)) } } impl<'tcx> PartialEq for TyS<'tcx> { #[inline] fn eq(&self, other: &TyS<'tcx>) -> bool { ptr::eq(self, other) } } impl<'tcx> Eq for TyS<'tcx> {} impl<'tcx> Hash for TyS<'tcx> { fn hash(&self, s: &mut H) { (self as *const TyS<'_>).hash(s) } } impl<'tcx> TyS<'tcx> { pub fn is_primitive_ty(&self) -> bool { match self.sty { TyKind::Bool | TyKind::Char | TyKind::Int(_) | TyKind::Uint(_) | TyKind::Float(_) | TyKind::Infer(InferTy::IntVar(_)) | TyKind::Infer(InferTy::FloatVar(_)) | TyKind::Infer(InferTy::FreshIntTy(_)) | TyKind::Infer(InferTy::FreshFloatTy(_)) => true, TyKind::Ref(_, x, _) => x.is_primitive_ty(), _ => false, } } pub fn is_suggestable(&self) -> bool { match self.sty { TyKind::Opaque(..) | TyKind::FnDef(..) | TyKind::FnPtr(..) | TyKind::Dynamic(..) | TyKind::Closure(..) | TyKind::Infer(..) | TyKind::Projection(..) => false, _ => true, } } } impl<'a, 'gcx> HashStable> for ty::TyS<'gcx> { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, 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: _, outer_exclusive_binder: _, } = *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> {} pub type CanonicalTy<'gcx> = Canonical<'gcx, Ty<'gcx>>; extern { /// A dummy type used to force List to by unsized without requiring fat pointers type OpaqueListContents; } /// 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 for both /// equality comparisons and hashing. /// Note: `Slice` was already taken by the `Ty`. #[repr(C)] pub struct List { len: usize, data: [T; 0], opaque: OpaqueListContents, } unsafe impl Sync for List {} impl List { #[inline] fn from_arena<'tcx>(arena: &'tcx SyncDroplessArena, slice: &[T]) -> &'tcx List { assert!(!mem::needs_drop::()); assert!(mem::size_of::() != 0); assert!(slice.len() != 0); // Align up the size of the len (usize) field let align = mem::align_of::(); let align_mask = align - 1; let offset = mem::size_of::(); let offset = (offset + align_mask) & !align_mask; let size = offset + slice.len() * mem::size_of::(); let mem = arena.alloc_raw( size, cmp::max(mem::align_of::(), mem::align_of::())); unsafe { let result = &mut *(mem.as_mut_ptr() as *mut List); // Write the length result.len = slice.len(); // Write the elements let arena_slice = slice::from_raw_parts_mut(result.data.as_mut_ptr(), result.len); arena_slice.copy_from_slice(slice); result } } } impl fmt::Debug for List { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { (**self).fmt(f) } } impl Encodable for List { #[inline] fn encode(&self, s: &mut S) -> Result<(), S::Error> { (**self).encode(s) } } impl Ord for List where T: Ord { fn cmp(&self, other: &List) -> Ordering { if self == other { Ordering::Equal } else { <[T] as Ord>::cmp(&**self, &**other) } } } impl PartialOrd for List where T: PartialOrd { fn partial_cmp(&self, other: &List) -> Option { if self == other { Some(Ordering::Equal) } else { <[T] as PartialOrd>::partial_cmp(&**self, &**other) } } } impl PartialEq for List { #[inline] fn eq(&self, other: &List) -> bool { ptr::eq(self, other) } } impl Eq for List {} impl Hash for List { #[inline] fn hash(&self, s: &mut H) { (self as *const List).hash(s) } } impl Deref for List { type Target = [T]; #[inline(always)] fn deref(&self) -> &[T] { unsafe { slice::from_raw_parts(self.data.as_ptr(), self.len) } } } impl<'a, T> IntoIterator for &'a List { type Item = &'a T; type IntoIter = <&'a [T] as IntoIterator>::IntoIter; #[inline(always)] fn into_iter(self) -> Self::IntoIter { self[..].iter() } } impl<'tcx> serialize::UseSpecializedDecodable for &'tcx List> {} impl List { #[inline(always)] pub fn empty<'a>() -> &'a List { #[repr(align(64), C)] struct EmptySlice([u8; 64]); static EMPTY_SLICE: EmptySlice = EmptySlice([0; 64]); assert!(mem::align_of::() <= 64); unsafe { &*(&EMPTY_SLICE as *const _ as *const List) } } } #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)] pub struct UpvarPath { pub hir_id: hir::HirId, } /// Upvars do not get their own `NodeId`. 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, HashStable)] pub struct UpvarId { pub var_path: UpvarPath, pub closure_expr_id: LocalDefId, } #[derive(Clone, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, Copy, HashStable)] 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, HashStable)] 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, HashStable)] 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 UpvarListMap = FxHashMap>; pub type UpvarCaptureMap<'tcx> = FxHashMap>; #[derive(Copy, Clone)] pub struct ClosureUpvar<'tcx> { pub res: Res, pub span: Span, pub ty: Ty<'tcx>, } #[derive(Clone, Copy, PartialEq, Eq)] pub enum IntVarValue { IntType(ast::IntTy), UintType(ast::UintTy), } #[derive(Clone, Copy, PartialEq, Eq)] pub struct FloatVarValue(pub ast::FloatTy); impl ty::EarlyBoundRegion { pub fn to_bound_region(&self) -> ty::BoundRegion { ty::BoundRegion::BrNamed(self.def_id, self.name) } /// 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 != keywords::UnderscoreLifetime.name().as_interned_str() } } #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub enum GenericParamDefKind { Lifetime, Type { has_default: bool, object_lifetime_default: ObjectLifetimeDefault, synthetic: Option, }, Const, } #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)] pub struct GenericParamDef { pub name: InternedString, pub def_id: DefId, pub index: u32, /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute /// on generic parameter `'a`/`T`, asserts data behind the parameter /// `'a`/`T` won't be accessed during the parent type's `Drop` impl. pub pure_wrt_drop: bool, pub kind: GenericParamDefKind, } impl GenericParamDef { pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion { if let GenericParamDefKind::Lifetime = self.kind { ty::EarlyBoundRegion { def_id: self.def_id, index: self.index, name: self.name, } } else { bug!("cannot convert a non-lifetime parameter def to an early bound region") } } pub fn to_bound_region(&self) -> ty::BoundRegion { if let GenericParamDefKind::Lifetime = self.kind { self.to_early_bound_region_data().to_bound_region() } else { bug!("cannot convert a non-lifetime parameter def to an early bound region") } } } #[derive(Default)] pub struct GenericParamCount { pub lifetimes: usize, pub types: usize, pub consts: usize, } /// Information about the formal type/lifetime parameters associated /// with an item or method. Analogous to `hir::Generics`. /// /// The ordering of parameters is the same as in `Subst` (excluding child generics): /// `Self` (optionally), `Lifetime` params..., `Type` params... #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct Generics { pub parent: Option, pub parent_count: usize, pub params: Vec, /// Reverse map to the `index` field of each `GenericParamDef` #[stable_hasher(ignore)] pub param_def_id_to_index: FxHashMap, pub has_self: bool, pub has_late_bound_regions: Option, } impl<'a, 'gcx, 'tcx> Generics { pub fn count(&self) -> usize { self.parent_count + self.params.len() } pub fn own_counts(&self) -> GenericParamCount { // We could cache this as a property of `GenericParamCount`, but // the aim is to refactor this away entirely eventually and the // presence of this method will be a constant reminder. let mut own_counts: GenericParamCount = Default::default(); for param in &self.params { match param.kind { GenericParamDefKind::Lifetime => own_counts.lifetimes += 1, GenericParamDefKind::Type { .. } => own_counts.types += 1, GenericParamDefKind::Const => own_counts.consts += 1, }; } own_counts } pub fn requires_monomorphization(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> bool { if self.own_requires_monomorphization() { return true; } if let Some(parent_def_id) = self.parent { let parent = tcx.generics_of(parent_def_id); parent.requires_monomorphization(tcx) } else { false } } pub fn own_requires_monomorphization(&self) -> bool { for param in &self.params { match param.kind { GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true, GenericParamDefKind::Lifetime => {} } } false } pub fn region_param(&'tcx self, param: &EarlyBoundRegion, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> &'tcx GenericParamDef { if let Some(index) = param.index.checked_sub(self.parent_count as u32) { let param = &self.params[index as usize]; match param.kind { GenericParamDefKind::Lifetime => param, _ => bug!("expected lifetime parameter, but found another generic parameter") } } else { tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?")) .region_param(param, tcx) } } /// Returns the `GenericParamDef` associated with this `ParamTy`. pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> &'tcx GenericParamDef { if let Some(index) = param.idx.checked_sub(self.parent_count as u32) { let param = &self.params[index as usize]; match param.kind { GenericParamDefKind::Type { .. } => param, _ => bug!("expected type parameter, but found another generic parameter") } } else { tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?")) .type_param(param, tcx) } } /// Returns the `ConstParameterDef` associated with this `ParamConst`. pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> &GenericParamDef { if let Some(index) = param.index.checked_sub(self.parent_count as u32) { let param = &self.params[index as usize]; match param.kind { GenericParamDefKind::Const => param, _ => bug!("expected const parameter, but found another generic parameter") } } else { tcx.generics_of(self.parent.expect("parent_count>0 but no parent?")) .const_param(param, tcx) } } } /// Bounds on generics. #[derive(Clone, Default, Debug, HashStable)] pub struct GenericPredicates<'tcx> { pub parent: Option, pub predicates: Vec<(Predicate<'tcx>, Span)>, } 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: SubstsRef<'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: SubstsRef<'tcx>) -> InstantiatedPredicates<'tcx> { InstantiatedPredicates { predicates: self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)).collect(), } } fn instantiate_into(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, instantiated: &mut InstantiatedPredicates<'tcx>, substs: SubstsRef<'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.iter().map(|&(p, _)| p)) } 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, HashStable)] 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 `'a: 'b` RegionOutlives(PolyRegionOutlivesPredicate<'tcx>), /// where `T: 'a` TypeOutlives(PolyTypeOutlivesPredicate<'tcx>), /// where `::Name == X`, approximately. /// See the `ProjectionPredicate` struct for details. Projection(PolyProjectionPredicate<'tcx>), /// no syntax: `T` well-formed 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, ClosureSubsts<'tcx>, ClosureKind), /// `T1 <: T2` Subtype(PolySubtypePredicate<'tcx>), /// Constant initializer must evaluate successfully. ConstEvaluatable(DefId, SubstsRef<'tcx>), } /// The crate outlives map is computed during typeck and contains the /// outlives of every item in the local crate. You should not use it /// directly, because to do so will make your pass dependent on the /// HIR of every item in the local crate. Instead, use /// `tcx.inferred_outlives_of()` to get the outlives for a *particular* /// item. #[derive(HashStable)] 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]>, } impl<'tcx> AsRef> for Predicate<'tcx> { fn as_ref(&self) -> &Predicate<'tcx> { self } } 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.skip_binder().substs; match *self { Predicate::Trait(ref binder) => Predicate::Trait(binder.map_bound(|data| data.subst(tcx, substs))), Predicate::Subtype(ref binder) => Predicate::Subtype(binder.map_bound(|data| data.subst(tcx, substs))), Predicate::RegionOutlives(ref binder) => Predicate::RegionOutlives(binder.map_bound(|data| data.subst(tcx, substs))), Predicate::TypeOutlives(ref binder) => Predicate::TypeOutlives(binder.map_bound(|data| data.subst(tcx, substs))), Predicate::Projection(ref binder) => Predicate::Projection(binder.map_bound(|data| 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, closure_substs, kind) => Predicate::ClosureKind(closure_def_id, closure_substs.subst(tcx, substs), kind), Predicate::ConstEvaluatable(def_id, const_substs) => Predicate::ConstEvaluatable(def_id, const_substs.subst(tcx, substs)), } } } #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)] 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.skip_binder().def_id() } } #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable, HashStable)] pub struct OutlivesPredicate(pub A, pub B); // `A: B` pub type PolyOutlivesPredicate = ty::Binder>; pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate, ty::Region<'tcx>>; pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate, ty::Region<'tcx>>; pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder>; pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder>; #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, HashStable)] 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, HashStable)] pub struct ProjectionPredicate<'tcx> { pub projection_ty: ProjectionTy<'tcx>, pub ty: Ty<'tcx>, } pub type PolyProjectionPredicate<'tcx> = Binder>; impl<'tcx> PolyProjectionPredicate<'tcx> { /// Returns the `DefId` of the associated item being projected. pub fn item_def_id(&self) -> DefId { self.skip_binder().projection_ty.item_def_id } #[inline] 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. self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx)) } pub fn ty(&self) -> Binder> { self.map_bound(|predicate| predicate.ty) } /// The `DefId` of the `TraitItem` for the associated type. /// /// Note that this is not the `DefId` of the `TraitRef` containing this /// associated type, which is in `tcx.associated_item(projection_def_id()).container`. pub fn projection_def_id(&self) -> DefId { // okay to skip binder since trait def-id does not care about regions self.skip_binder().projection_ty.item_def_id } } pub trait ToPolyTraitRef<'tcx> { fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>; } impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> { fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> { ty::Binder::dummy(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> { ty::Predicate::Trait(ty::Binder::dummy(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 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()) } } // A custom iterator used by Predicate::walk_tys. enum WalkTysIter<'tcx, I, J, K> where I: Iterator>, J: Iterator>, K: Iterator> { None, One(Ty<'tcx>), Two(Ty<'tcx>, Ty<'tcx>), Types(I), InputTypes(J), ProjectionTypes(K) } impl<'tcx, I, J, K> Iterator for WalkTysIter<'tcx, I, J, K> where I: Iterator>, J: Iterator>, K: Iterator> { type Item = Ty<'tcx>; fn next(&mut self) -> Option> { match *self { WalkTysIter::None => None, WalkTysIter::One(item) => { *self = WalkTysIter::None; Some(item) }, WalkTysIter::Two(item1, item2) => { *self = WalkTysIter::One(item2); Some(item1) }, WalkTysIter::Types(ref mut iter) => { iter.next() }, WalkTysIter::InputTypes(ref mut iter) => { iter.next() }, WalkTysIter::ProjectionTypes(ref mut iter) => { iter.next() } } } } 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(&'a self) -> impl Iterator> + 'a { match *self { ty::Predicate::Trait(ref data) => { WalkTysIter::InputTypes(data.skip_binder().input_types()) } ty::Predicate::Subtype(binder) => { let SubtypePredicate { a, b, a_is_expected: _ } = binder.skip_binder(); WalkTysIter::Two(a, b) } ty::Predicate::TypeOutlives(binder) => { WalkTysIter::One(binder.skip_binder().0) } ty::Predicate::RegionOutlives(..) => { WalkTysIter::None } ty::Predicate::Projection(ref data) => { let inner = data.skip_binder(); WalkTysIter::ProjectionTypes( inner.projection_ty.substs.types().chain(Some(inner.ty))) } ty::Predicate::WellFormed(data) => { WalkTysIter::One(data) } ty::Predicate::ObjectSafe(_trait_def_id) => { WalkTysIter::None } ty::Predicate::ClosureKind(_closure_def_id, closure_substs, _kind) => { WalkTysIter::Types(closure_substs.substs.types()) } ty::Predicate::ConstEvaluatable(_, substs) => { WalkTysIter::Types(substs.types()) } } } pub fn to_opt_poly_trait_ref(&self) -> Option> { match *self { Predicate::Trait(ref t) => { Some(t.to_poly_trait_ref()) } Predicate::Projection(..) | Predicate::Subtype(..) | Predicate::RegionOutlives(..) | Predicate::WellFormed(..) | Predicate::ObjectSafe(..) | Predicate::ClosureKind(..) | Predicate::TypeOutlives(..) | Predicate::ConstEvaluatable(..) => { None } } } pub fn to_opt_type_outlives(&self) -> Option> { match *self { Predicate::TypeOutlives(data) => { Some(data) } Predicate::Trait(..) | Predicate::Projection(..) | Predicate::Subtype(..) | Predicate::RegionOutlives(..) | Predicate::WellFormed(..) | Predicate::ObjectSafe(..) | Predicate::ClosureKind(..) | Predicate::ConstEvaluatable(..) => { 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, Debug)] 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() } } newtype_index! { /// "Universes" are used during type- and trait-checking in the /// presence of `for<..>` binders to control what sets of names are /// visible. Universes are arranged into a tree: the root universe /// contains names that are always visible. Each child then adds a new /// set of names that are visible, in addition to those of its parent. /// We say that the child universe "extends" the parent universe with /// new names. /// /// To make this more concrete, consider this program: /// /// ``` /// struct Foo { } /// fn bar(x: T) { /// let y: for<'a> fn(&'a u8, Foo) = ...; /// } /// ``` /// /// The struct name `Foo` is in the root universe U0. But the type /// parameter `T`, introduced on `bar`, is in an extended universe U1 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside /// of `bar`, we cannot name `T`. Then, within the type of `y`, the /// region `'a` is in a universe U2 that extends U1, because we can /// name it inside the fn type but not outside. /// /// Universes are used to do type- and trait-checking around these /// "forall" binders (also called **universal quantification**). The /// idea is that when, in the body of `bar`, we refer to `T` as a /// type, we aren't referring to any type in particular, but rather a /// kind of "fresh" type that is distinct from all other types we have /// actually declared. This is called a **placeholder** type, and we /// use universes to talk about this. In other words, a type name in /// universe 0 always corresponds to some "ground" type that the user /// declared, but a type name in a non-zero universe is a placeholder /// type -- an idealized representative of "types in general" that we /// use for checking generic functions. pub struct UniverseIndex { DEBUG_FORMAT = "U{}", } } impl_stable_hash_for!(struct UniverseIndex { private }); impl UniverseIndex { pub const ROOT: UniverseIndex = UniverseIndex::from_u32_const(0); /// Returns the "next" universe index in order -- this new index /// is considered to extend all previous universes. This /// corresponds to entering a `forall` quantifier. So, for /// example, suppose we have this type in universe `U`: /// /// ``` /// for<'a> fn(&'a u32) /// ``` /// /// Once we "enter" into this `for<'a>` quantifier, we are in a /// new universe that extends `U` -- in this new universe, we can /// name the region `'a`, but that region was not nameable from /// `U` because it was not in scope there. pub fn next_universe(self) -> UniverseIndex { UniverseIndex::from_u32(self.private.checked_add(1).unwrap()) } /// Returns `true` if `self` can name a name from `other` -- in other words, /// if the set of names in `self` is a superset of those in /// `other` (`self >= other`). pub fn can_name(self, other: UniverseIndex) -> bool { self.private >= other.private } /// Returns `true` if `self` cannot name some names from `other` -- in other /// words, if the set of names in `self` is a strict subset of /// those in `other` (`self < other`). pub fn cannot_name(self, other: UniverseIndex) -> bool { self.private < other.private } } /// The "placeholder index" fully defines a placeholder region. /// Placeholder regions are identified by both a **universe** as well /// as a "bound-region" within that universe. The `bound_region` is /// basically a name -- distinct bound regions within the same /// universe are just two regions with an unknown relationship to one /// another. #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)] pub struct Placeholder { pub universe: UniverseIndex, pub name: T, } impl<'a, 'gcx, T> HashStable> for Placeholder where T: HashStable> { fn hash_stable( &self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher ) { self.universe.hash_stable(hcx, hasher); self.name.hash_stable(hcx, hasher); } } pub type PlaceholderRegion = Placeholder; pub type PlaceholderType = Placeholder; pub type PlaceholderConst = Placeholder; /// 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, HashStable)] 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 List>, /// Typically, this is `Reveal::UserFacing`, but during codegen we /// want `Reveal::All` -- note that this is always paired with an /// empty environment. To get that, use `ParamEnv::reveal()`. pub reveal: traits::Reveal, /// If this `ParamEnv` comes from a call to `tcx.param_env(def_id)`, /// register that `def_id` (useful for transitioning to the chalk trait /// solver). pub def_id: Option, } 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, None) } /// 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, None) } /// Construct a trait environment with the given set of predicates. #[inline] pub fn new( caller_bounds: &'tcx List>, reveal: Reveal, def_id: Option ) -> Self { ty::ParamEnv { caller_bounds, reveal, def_id } } /// 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. pub fn with_reveal_all(self) -> Self { ty::ParamEnv { reveal: Reveal::All, ..self } } /// Returns this same environment but with no caller bounds. pub fn without_caller_bounds(self) -> Self { ty::ParamEnv { caller_bounds: List::empty(), ..self } } /// 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.has_placeholders() || value.needs_infer() || value.has_param_types() || value.has_self_ty() { ParamEnvAnd { param_env: self, value, } } else { ParamEnvAnd { param_env: self.without_caller_bounds(), 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) } } impl<'a, 'gcx, T> HashStable> for ParamEnvAnd<'gcx, T> where T: HashStable> { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { let ParamEnvAnd { ref param_env, ref value } = *self; param_env.hash_stable(hcx, hasher); value.hash_stable(hcx, hasher); } } #[derive(Copy, Clone, Debug, HashStable)] pub struct Destructor { /// The `DefId` of the destructor method pub did: DefId, } bitflags! { #[derive(HashStable)] pub struct AdtFlags: u32 { const NO_ADT_FLAGS = 0; /// Indicates whether the ADT is an enum. const IS_ENUM = 1 << 0; /// Indicates whether the ADT is a union. const IS_UNION = 1 << 1; /// Indicates whether the ADT is a struct. const IS_STRUCT = 1 << 2; /// Indicates whether the ADT is a struct and has a constructor. const HAS_CTOR = 1 << 3; /// Indicates whether the type is a `PhantomData`. const IS_PHANTOM_DATA = 1 << 4; /// Indicates whether the type has a `#[fundamental]` attribute. const IS_FUNDAMENTAL = 1 << 5; /// Indicates whether the type is a `Box`. const IS_BOX = 1 << 6; /// Indicates whether the type is an `Arc`. const IS_ARC = 1 << 7; /// Indicates whether the type is an `Rc`. const IS_RC = 1 << 8; /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`. /// (i.e., this flag is never set unless this ADT is an enum). const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 9; } } bitflags! { #[derive(HashStable)] pub struct VariantFlags: u32 { const NO_VARIANT_FLAGS = 0; /// Indicates whether the field list of this variant is `#[non_exhaustive]`. const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0; } } /// Definition of a variant -- a struct's fields or a enum variant. #[derive(Debug)] pub struct VariantDef { /// `DefId` that identifies the variant itself. /// If this variant belongs to a struct or union, then this is a copy of its `DefId`. pub def_id: DefId, /// `DefId` that identifies the variant's constructor. /// If this variant is a struct variant, then this is `None`. pub ctor_def_id: Option, /// Variant or struct name. pub ident: Ident, /// Discriminant of this variant. pub discr: VariantDiscr, /// Fields of this variant. pub fields: Vec, /// Type of constructor of variant. pub ctor_kind: CtorKind, /// Flags of the variant (e.g. is field list non-exhaustive)? flags: VariantFlags, /// Recovered? pub recovered: bool, } impl<'a, 'gcx, 'tcx> 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( tcx: TyCtxt<'a, 'gcx, 'tcx>, ident: Ident, variant_did: Option, ctor_def_id: Option, discr: VariantDiscr, fields: Vec, ctor_kind: CtorKind, adt_kind: AdtKind, parent_did: DefId, recovered: bool, ) -> Self { debug!( "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?}, fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})", ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did, ); let mut flags = VariantFlags::NO_VARIANT_FLAGS; if adt_kind == AdtKind::Struct && tcx.has_attr(parent_did, "non_exhaustive") { debug!("found non-exhaustive field list for {:?}", parent_did); flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE; } else if let Some(variant_did) = variant_did { if tcx.has_attr(variant_did, "non_exhaustive") { debug!("found non-exhaustive field list for {:?}", variant_did); flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE; } } VariantDef { def_id: variant_did.unwrap_or(parent_did), ctor_def_id, ident, discr, fields, ctor_kind, flags, recovered, } } /// 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) } } impl_stable_hash_for!(struct VariantDef { def_id, ctor_def_id, ident -> (ident.name), discr, fields, ctor_kind, flags, recovered }); #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)] pub enum VariantDiscr { /// Explicit value for this variant, i.e., `X = 123`. /// The `DefId` corresponds to the embedded constant. Explicit(DefId), /// The previous variant's discriminant plus one. /// For efficiency reasons, the distance from the /// last `Explicit` discriminant is being stored, /// or `0` for the first variant, if it has none. Relative(u32), } #[derive(Debug, HashStable)] pub struct FieldDef { pub did: DefId, #[stable_hasher(project(name))] pub ident: Ident, pub vis: Visibility, } /// 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 { /// `DefId` of the struct, enum or union item. pub did: DefId, /// Variants of the ADT. If this is a struct or enum, then there will be a single variant. pub variants: IndexVec, /// Flags of the ADT (e.g. is this a struct? is this non-exhaustive?) flags: AdtFlags, /// Repr options provided by the user. pub repr: ReprOptions, } impl PartialOrd for AdtDef { fn partial_cmp(&self, other: &AdtDef) -> Option { Some(self.cmp(&other)) } } /// There should be only one AdtDef for each `did`, therefore /// it is fine to implement `Ord` only based on `did`. impl Ord for AdtDef { fn cmp(&self, other: &AdtDef) -> Ordering { self.did.cmp(&other.did) } } impl PartialEq for AdtDef { // AdtDef are always interned and this is part of TyS equality #[inline] fn eq(&self, other: &Self) -> bool { ptr::eq(self, other) } } 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> HashStable> for AdtDef { fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) { thread_local! { static CACHE: RefCell> = Default::default(); } let hash: Fingerprint = CACHE.with(|cache| { let addr = self as *const AdtDef as usize; *cache.borrow_mut().entry(addr).or_insert_with(|| { let ty::AdtDef { did, ref variants, ref flags, ref repr, } = *self; let mut hasher = StableHasher::new(); did.hash_stable(hcx, &mut hasher); variants.hash_stable(hcx, &mut hasher); flags.hash_stable(hcx, &mut hasher); repr.hash_stable(hcx, &mut hasher); hasher.finish() }) }); hash.hash_stable(hcx, hasher); } } #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)] pub enum AdtKind { Struct, Union, Enum } impl Into for AdtKind { fn into(self) -> DataTypeKind { match self { AdtKind::Struct => DataTypeKind::Struct, AdtKind::Union => DataTypeKind::Union, AdtKind::Enum => DataTypeKind::Enum, } } } bitflags! { #[derive(RustcEncodable, RustcDecodable, Default)] pub struct ReprFlags: u8 { const IS_C = 1 << 0; const IS_SIMD = 1 << 1; const IS_TRANSPARENT = 1 << 2; // Internal only for now. If true, don't reorder fields. const IS_LINEAR = 1 << 3; // Any of these flags being set prevent field reordering optimisation. const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits | ReprFlags::IS_SIMD.bits | ReprFlags::IS_LINEAR.bits; } } impl_stable_hash_for!(struct ReprFlags { bits }); /// Represents the repr options provided by the user, #[derive(Copy, Clone, Debug, Eq, PartialEq, RustcEncodable, RustcDecodable, Default)] pub struct ReprOptions { pub int: Option, pub align: u32, pub pack: u32, pub flags: ReprFlags, } impl_stable_hash_for!(struct ReprOptions { align, pack, 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; let mut min_pack = 0; for attr in tcx.get_attrs(did).iter() { for r in attr::find_repr_attrs(&tcx.sess.parse_sess, attr) { flags.insert(match r { attr::ReprC => ReprFlags::IS_C, attr::ReprPacked(pack) => { min_pack = if min_pack > 0 { cmp::min(pack, min_pack) } else { pack }; ReprFlags::empty() }, attr::ReprTransparent => ReprFlags::IS_TRANSPARENT, 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() }, }); } } // This is here instead of layout because the choice must make it into metadata. if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) { flags.insert(ReprFlags::IS_LINEAR); } ReprOptions { int: size, align: max_align, pack: min_pack, 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.pack > 0 } #[inline] pub fn transparent(&self) -> bool { self.flags.contains(ReprFlags::IS_TRANSPARENT) } #[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::Isize)) } /// Returns `true` if this `#[repr()]` should inhabit "smart enum /// layout" optimizations, such as representing `Foo<&T>` as a /// single pointer. pub fn inhibit_enum_layout_opt(&self) -> bool { self.c() || self.int.is_some() } /// Returns `true` if this `#[repr()]` should inhibit struct field reordering /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr()`. pub fn inhibit_struct_field_reordering_opt(&self) -> bool { self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.pack == 1 || self.int.is_some() } /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations. pub fn inhibit_union_abi_opt(&self) -> bool { self.c() } } impl<'a, 'gcx, 'tcx> AdtDef { /// Creates a new `AdtDef`. fn new( tcx: TyCtxt<'_, '_, '_>, did: DefId, kind: AdtKind, variants: IndexVec, repr: ReprOptions ) -> Self { debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr); let mut flags = AdtFlags::NO_ADT_FLAGS; if kind == AdtKind::Enum && tcx.has_attr(did, "non_exhaustive") { debug!("found non-exhaustive variant list for {:?}", did); flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE; } flags |= match kind { AdtKind::Enum => AdtFlags::IS_ENUM, AdtKind::Union => AdtFlags::IS_UNION, AdtKind::Struct => AdtFlags::IS_STRUCT, }; if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() { flags |= AdtFlags::HAS_CTOR; } let attrs = tcx.get_attrs(did); if attr::contains_name(&attrs, "fundamental") { flags |= AdtFlags::IS_FUNDAMENTAL; } if Some(did) == tcx.lang_items().phantom_data() { flags |= AdtFlags::IS_PHANTOM_DATA; } if Some(did) == tcx.lang_items().owned_box() { flags |= AdtFlags::IS_BOX; } if Some(did) == tcx.lang_items().arc() { flags |= AdtFlags::IS_ARC; } if Some(did) == tcx.lang_items().rc() { flags |= AdtFlags::IS_RC; } AdtDef { did, variants, flags, repr, } } /// Returns `true` if this is a struct. #[inline] pub fn is_struct(&self) -> bool { self.flags.contains(AdtFlags::IS_STRUCT) } /// Returns `true` if this is a union. #[inline] pub fn is_union(&self) -> bool { self.flags.contains(AdtFlags::IS_UNION) } /// Returns `true` if this is a enum. #[inline] pub fn is_enum(&self) -> bool { self.flags.contains(AdtFlags::IS_ENUM) } /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`. #[inline] pub fn is_variant_list_non_exhaustive(&self) -> bool { self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE) } /// Returns the kind of the ADT. #[inline] pub fn adt_kind(&self) -> AdtKind { if self.is_enum() { AdtKind::Enum } else if self.is_union() { AdtKind::Union } else { AdtKind::Struct } } /// Returns a description of this abstract data type. pub fn descr(&self) -> &'static str { match self.adt_kind() { AdtKind::Struct => "struct", AdtKind::Union => "union", AdtKind::Enum => "enum", } } /// Returns a description of a variant of this abstract data type. #[inline] pub fn variant_descr(&self) -> &'static str { match self.adt_kind() { AdtKind::Struct => "struct", AdtKind::Union => "union", AdtKind::Enum => "variant", } } /// If this function returns `true`, it implies that `is_struct` must return `true`. #[inline] pub fn has_ctor(&self) -> bool { self.flags.contains(AdtFlags::HAS_CTOR) } /// Returns `true` if this type is `#[fundamental]` for the purposes /// of coherence checking. #[inline] pub fn is_fundamental(&self) -> bool { self.flags.contains(AdtFlags::IS_FUNDAMENTAL) } /// Returns `true` if this is `PhantomData`. #[inline] pub fn is_phantom_data(&self) -> bool { self.flags.contains(AdtFlags::IS_PHANTOM_DATA) } /// Returns `true` if this is `Arc`. pub fn is_arc(&self) -> bool { self.flags.contains(AdtFlags::IS_ARC) } /// Returns `true` if this is `Rc`. pub fn is_rc(&self) -> bool { self.flags.contains(AdtFlags::IS_RC) } /// Returns `true` if this is Box. #[inline] pub fn is_box(&self) -> bool { self.flags.contains(AdtFlags::IS_BOX) } /// Returns `true` if 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 or union and returns its unique variant. pub fn non_enum_variant(&self) -> &VariantDef { assert!(self.is_struct() || self.is_union()); &self.variants[VariantIdx::new(0)] } #[inline] pub fn predicates(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>) -> Lrc> { 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()) } pub fn is_payloadfree(&self) -> bool { !self.variants.is_empty() && self.variants.iter().all(|v| v.fields.is_empty()) } /// Return a `VariantDef` given a variant id. pub fn variant_with_id(&self, vid: DefId) -> &VariantDef { self.variants.iter().find(|v| v.def_id == vid) .expect("variant_with_id: unknown variant") } /// Return a `VariantDef` given a constructor id. pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef { self.variants.iter().find(|v| v.ctor_def_id == Some(cid)) .expect("variant_with_ctor_id: unknown variant") } /// Return the index of `VariantDef` given a variant id. pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx { self.variants.iter_enumerated().find(|(_, v)| v.def_id == vid) .expect("variant_index_with_id: unknown variant").0 } /// Return the index of `VariantDef` given a constructor id. pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx { self.variants.iter_enumerated().find(|(_, v)| v.ctor_def_id == Some(cid)) .expect("variant_index_with_ctor_id: unknown variant").0 } pub fn variant_of_res(&self, res: Res) -> &VariantDef { match res { Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid), Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid), Res::Def(DefKind::Struct, _) | Res::Def(DefKind::Union, _) | Res::Def(DefKind::TyAlias, _) | Res::Def(DefKind::AssociatedTy, _) | Res::SelfTy(..) | Res::SelfCtor(..) => self.non_enum_variant(), _ => bug!("unexpected res {:?} in variant_of_res", res) } } #[inline] pub fn eval_explicit_discr( &self, tcx: TyCtxt<'a, 'gcx, 'tcx>, expr_did: DefId, ) -> Option> { let param_env = ParamEnv::empty(); let repr_type = self.repr.discr_type(); let substs = InternalSubsts::identity_for_item(tcx.global_tcx(), expr_did); let instance = ty::Instance::new(expr_did, substs); let cid = GlobalId { instance, promoted: None }; match tcx.const_eval(param_env.and(cid)) { Ok(val) => { // FIXME: Find the right type and use it instead of `val.ty` here if let Some(b) = val.assert_bits(tcx.global_tcx(), param_env.and(val.ty)) { trace!("discriminants: {} ({:?})", b, repr_type); Some(Discr { val: b, ty: val.ty, }) } else { info!("invalid enum discriminant: {:#?}", val); crate::mir::interpret::struct_error( tcx.at(tcx.def_span(expr_did)), "constant evaluation of enum discriminant resulted in non-integer", ).emit(); None } } Err(ErrorHandled::Reported) => { if !expr_did.is_local() { span_bug!(tcx.def_span(expr_did), "variant discriminant evaluation succeeded \ in its crate but failed locally"); } None } Err(ErrorHandled::TooGeneric) => span_bug!( tcx.def_span(expr_did), "enum discriminant depends on generic arguments", ), } } #[inline] pub fn discriminants( &'a self, tcx: TyCtxt<'a, 'gcx, 'tcx>, ) -> impl Iterator)> + Captures<'gcx> + 'a { let repr_type = self.repr.discr_type(); let initial = repr_type.initial_discriminant(tcx.global_tcx()); let mut prev_discr = None::>; self.variants.iter_enumerated().map(move |(i, v)| { let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx)); if let VariantDiscr::Explicit(expr_did) = v.discr { if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) { discr = new_discr; } } prev_discr = Some(discr); (i, discr) }) } #[inline] pub fn variant_range(&self) -> Range { (VariantIdx::new(0)..VariantIdx::new(self.variants.len())) } /// Computes 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. #[inline] pub fn discriminant_for_variant(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, variant_index: VariantIdx) -> Discr<'tcx> { let (val, offset) = self.discriminant_def_for_variant(variant_index); let explicit_value = val .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did)) .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx.global_tcx())); explicit_value.checked_add(tcx, offset as u128).0 } /// Yields a `DefId` for the discriminant and an offset to add to it /// Alternatively, if there is no explicit discriminant, returns the /// inferred discriminant directly. pub fn discriminant_def_for_variant( &self, variant_index: VariantIdx, ) -> (Option, u32) { let mut explicit_index = variant_index.as_u32(); let expr_did; loop { match self.variants[VariantIdx::from_u32(explicit_index)].discr { ty::VariantDiscr::Relative(0) => { expr_did = None; break; }, ty::VariantDiscr::Relative(distance) => { explicit_index -= distance; } ty::VariantDiscr::Explicit(did) => { expr_did = Some(did); break; } } } (expr_did, variant_index.as_u32() - explicit_index) } 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>] { tcx.adt_sized_constraint(self.did).0 } fn sized_constraint_for_ty(&self, tcx: TyCtxt<'a, 'tcx, 'tcx>, ty: Ty<'tcx>) -> Vec> { let result = match ty.sty { Bool | Char | Int(..) | Uint(..) | Float(..) | RawPtr(..) | Ref(..) | FnDef(..) | FnPtr(_) | Array(..) | Closure(..) | Generator(..) | Never => { vec![] } Str | Dynamic(..) | Slice(_) | Foreign(..) | Error | GeneratorWitness(..) => { // these are never sized - return the target type vec![ty] } Tuple(ref tys) => { match tys.last() { None => vec![], Some(ty) => self.sized_constraint_for_ty(tcx, ty.expect_ty()), } } Adt(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() } Projection(..) | Opaque(..) => { // must calculate explicitly. // FIXME: consider special-casing always-Sized projections vec![ty] } UnnormalizedProjection(..) => bug!("only used with chalk-engine"), Param(..) => { // 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::dummy(TraitRef { def_id: sized_trait, substs: tcx.mk_substs_trait(ty, &[]) }).to_predicate(); let predicates = &tcx.predicates_of(self.did).predicates; if predicates.iter().any(|(p, _)| *p == sized_predicate) { vec![] } else { vec![ty] } } Placeholder(..) | Bound(..) | Infer(..) => { bug!("unexpected type `{:?}` in sized_constraint_for_ty", ty) } }; debug!("sized_constraint_for_ty({:?}) = {:?}", ty, result); result } } impl<'a, 'gcx, 'tcx> FieldDef { pub fn ty(&self, tcx: TyCtxt<'a, 'gcx, 'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> { tcx.type_of(self.did).subst(tcx, subst) } } /// Represents the various closure traits in the language. This /// will determine the type of the environment (`self`, in the /// desugaring) argument that the closure expects. /// /// You can get the environment type of a closure using /// `tcx.closure_env_ty()`. #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable, HashStable)] 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 { // This is the initial value used when doing upvar inference. pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn; 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) } } } /// Returns `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, } } /// Returns the representative scalar type for this closure kind. /// See `TyS::to_opt_closure_kind` for more details. pub fn to_ty(self, tcx: TyCtxt<'_, '_, 'tcx>) -> Ty<'tcx> { match self { ty::ClosureKind::Fn => tcx.types.i8, ty::ClosureKind::FnMut => tcx.types.i16, ty::ClosureKind::FnOnce => tcx.types.i32, } } } 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) -> smallvec::IntoIter> { 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(); } } } } 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(Lrc<[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 } } } #[derive(Debug, PartialEq, Eq)] pub enum ImplOverlapKind { /// These impls are always allowed to overlap. Permitted, /// These impls are allowed to overlap, but that raises /// an issue #33140 future-compatibility warning. /// /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different. /// /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied /// that difference, making what reduces to the following set of impls: /// /// ``` /// trait Trait {} /// impl Trait for dyn Send + Sync {} /// impl Trait for dyn Sync + Send {} /// ``` /// /// Obviously, once we made these types be identical, that code causes a coherence /// error and a fairly big headache for us. However, luckily for us, the trait /// `Trait` used in this case is basically a marker trait, and therefore having /// overlapping impls for it is sound. /// /// To handle this, we basically regard the trait as a marker trait, with an additional /// future-compatibility warning. To avoid accidentally "stabilizing" this feature, /// it has the following restrictions: /// /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be /// positive impls. /// 2. The trait-ref of both impls must be equal. /// 3. The trait-ref of both impls must be a trait object type consisting only of /// marker traits. /// 4. Neither of the impls can have any where-clauses. /// /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed. Issue33140 } impl<'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 `DefId`s 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 + Captures<'tcx> + Captures<'gcx> + 'a { self.hir().krate() .body_ids .iter() .map(move |&body_id| self.hir().body_owner_def_id(body_id)) } pub fn par_body_owners(self, f: F) { par_iter(&self.hir().krate().body_ids).for_each(|&body_id| { f(self.hir().body_owner_def_id(body_id)) }); } pub fn expr_span(self, id: NodeId) -> Span { match self.hir().find(id) { Some(Node::Expr(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 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(hir_id) = self.hir().as_local_hir_id(def_id) { match self.hir().get_by_hir_id(hir_id) { Node::TraitItem(_) | Node::ImplItem(_) => true, _ => false, } } else { match self.def_kind(def_id).expect("no def for def-id") { DefKind::AssociatedConst | DefKind::Method | DefKind::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_from_hir_id(trait_item_ref.id.hir_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), hir::AssociatedItemKind::Existential => bug!("only impls can have existentials"), }; AssociatedItem { ident: trait_item_ref.ident, kind, // Visibility of trait items is inherited from their traits. vis: Visibility::from_hir(parent_vis, trait_item_ref.id.hir_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_from_hir_id(impl_item_ref.id.hir_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), hir::AssociatedItemKind::Existential => (ty::AssociatedKind::Existential, false), }; AssociatedItem { ident: impl_item_ref.ident, kind, // Visibility of trait impl items doesn't matter. vis: ty::Visibility::from_hir(&impl_item_ref.vis, impl_item_ref.id.hir_id, self), defaultness: impl_item_ref.defaultness, def_id, container: ImplContainer(parent_def_id), method_has_self_argument: has_self } } pub fn field_index(self, hir_id: hir::HirId, tables: &TypeckTables<'_>) -> usize { tables.field_indices().get(hir_id).cloned().expect("no index for a field") } pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option { variant.fields.iter().position(|field| { self.adjust_ident(ident, variant.def_id, hir::DUMMY_HIR_ID).0 == field.ident.modern() }) } pub fn associated_items( self, def_id: DefId, ) -> AssociatedItemsIterator<'a, 'gcx, 'tcx> { // Ideally, we would use `-> impl Iterator` here, but it falls // afoul of the conservative "capture [restrictions]" we put // in place, so we use a hand-written iterator. // // [restrictions]: https://github.com/rust-lang/rust/issues/34511#issuecomment-373423999 AssociatedItemsIterator { tcx: self, def_ids: self.associated_item_def_ids(def_id), next_index: 0, } } /// 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 { let is_legit = if self.features().overlapping_marker_traits { 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 } else { let is_marker_impl = |def_id: DefId| -> bool { let trait_ref = self.impl_trait_ref(def_id); trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker) }; self.impl_polarity(def_id1) == self.impl_polarity(def_id2) && is_marker_impl(def_id1) && is_marker_impl(def_id2) }; if is_legit { debug!("impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted)", def_id1, def_id2); Some(ImplOverlapKind::Permitted) } else { if let Some(self_ty1) = self.issue33140_self_ty(def_id1) { if let Some(self_ty2) = self.issue33140_self_ty(def_id2) { if self_ty1 == self_ty2 { debug!("impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK", def_id1, def_id2); return Some(ImplOverlapKind::Issue33140); } else { debug!("impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}", def_id1, def_id2, self_ty1, self_ty2); } } } debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2); None } } /// Returns `ty::VariantDef` if `res` refers to a struct, /// or variant or their constructors, panics otherwise. pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef { match res { Res::Def(DefKind::Variant, did) => { let enum_did = self.parent(did).unwrap(); self.adt_def(enum_did).variant_with_id(did) } Res::Def(DefKind::Struct, did) | Res::Def(DefKind::Union, did) => { self.adt_def(did).non_enum_variant() } Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => { let variant_did = self.parent(variant_ctor_did).unwrap(); let enum_did = self.parent(variant_did).unwrap(); self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did) } Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => { let struct_did = self.parent(ctor_did).expect("struct ctor has no parent"); self.adt_def(struct_did).non_enum_variant() } _ => bug!("expect_variant_res used with unexpected res {:?}", res) } } pub fn item_name(self, id: DefId) -> InternedString { if id.index == CRATE_DEF_INDEX { self.original_crate_name(id.krate).as_interned_str() } else { let def_key = self.def_key(id); match def_key.disambiguated_data.data { // The name of a constructor is that of its parent. hir_map::DefPathData::Ctor => self.item_name(DefId { krate: id.krate, index: def_key.parent.unwrap() }), _ => def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| { bug!("item_name: no name for {:?}", self.def_path(id)); }), } } } /// Returns 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::VtableShim(..) | ty::InstanceDef::Intrinsic(..) | ty::InstanceDef::FnPtrShim(..) | ty::InstanceDef::Virtual(..) | ty::InstanceDef::ClosureOnceShim { .. } | ty::InstanceDef::DropGlue(..) | ty::InstanceDef::CloneShim(..) => { self.mir_shims(instance) } } } /// Gets the attributes of a definition. pub fn get_attrs(self, did: DefId) -> Attributes<'gcx> { if let Some(id) = self.hir().as_local_hir_id(did) { Attributes::Borrowed(self.hir().attrs_by_hir_id(id)) } else { Attributes::Owned(self.item_attrs(did)) } } /// Determines whether an item is annotated with an attribute. pub fn has_attr(self, did: DefId, attr: &str) -> bool { attr::contains_name(&self.get_attrs(did), attr) } /// Returns `true` if this is an `auto trait`. pub fn trait_is_auto(self, trait_def_id: DefId) -> bool { self.trait_def(trait_def_id).has_auto_impl } pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> { self.optimized_mir(def_id).generator_layout.as_ref().unwrap() } /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements. /// If it implements no trait, returns `None`. pub fn trait_id_of_impl(self, def_id: DefId) -> Option { self.impl_trait_ref(def_id).map(|tr| tr.def_id) } /// If the given defid describes a method belonging to an impl, returns the /// `DefId` of the impl that the method belongs to; otherwise, returns `None`. pub fn impl_of_method(self, def_id: DefId) -> Option { let item = if def_id.krate != LOCAL_CRATE { if let Some(DefKind::Method) = self.def_kind(def_id) { Some(self.associated_item(def_id)) } else { None } } else { self.opt_associated_item(def_id) }; item.and_then(|trait_item| match trait_item.container { TraitContainer(_) => None, ImplContainer(def_id) => Some(def_id), } ) } /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err` /// with the name of the crate containing the impl. pub fn span_of_impl(self, impl_did: DefId) -> Result { if impl_did.is_local() { let hir_id = self.hir().as_local_hir_id(impl_did).unwrap(); Ok(self.hir().span_by_hir_id(hir_id)) } else { Err(self.crate_name(impl_did.krate)) } } /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed /// definition's parent/scope to perform comparison. pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool { self.adjust_ident(use_name, def_parent_def_id, hir::DUMMY_HIR_ID).0 == def_name.modern() } pub fn adjust_ident(self, mut ident: Ident, scope: DefId, block: hir::HirId) -> (Ident, DefId) { ident = ident.modern(); let target_expansion = match scope.krate { LOCAL_CRATE => self.hir().definitions().expansion_that_defined(scope.index), _ => Mark::root(), }; let scope = match ident.span.adjust(target_expansion) { Some(actual_expansion) => self.hir().definitions().parent_module_of_macro_def(actual_expansion), None if block == hir::DUMMY_HIR_ID => DefId::local(CRATE_DEF_INDEX), // Dummy DefId None => self.hir().get_module_parent_by_hir_id(block), }; (ident, scope) } } pub struct AssociatedItemsIterator<'a, 'gcx: 'tcx, 'tcx: 'a> { tcx: TyCtxt<'a, 'gcx, 'tcx>, def_ids: Lrc>, next_index: usize, } impl Iterator for AssociatedItemsIterator<'_, '_, '_> { type Item = AssociatedItem; fn next(&mut self) -> Option { let def_id = self.def_ids.get(self.next_index)?; self.next_index += 1; Some(self.tcx.associated_item(*def_id)) } } fn associated_item<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> AssociatedItem { let id = tcx.hir().as_local_hir_id(def_id).unwrap(); let parent_id = tcx.hir().get_parent_item(id); let parent_def_id = tcx.hir().local_def_id_from_hir_id(parent_id); let parent_item = tcx.hir().expect_item_by_hir_id(parent_id); match parent_item.node { hir::ItemKind::Impl(.., ref impl_item_refs) => { if let Some(impl_item_ref) = impl_item_refs.iter().find(|i| i.id.hir_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::ItemKind::Trait(.., ref trait_item_refs) => { if let Some(trait_item_ref) = trait_item_refs.iter().find(|i| i.id.hir_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) } #[derive(Clone, HashStable)] pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]); /// 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 Error, 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) -> AdtSizedConstraint<'tcx> { let def = tcx.adt_def(def_id); let result = tcx.mk_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)) })); debug!("adt_sized_constraint: {:?} => {:?}", def, result); AdtSizedConstraint(result) } fn associated_item_def_ids<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Lrc> { let id = tcx.hir().as_local_hir_id(def_id).unwrap(); let item = tcx.hir().expect_item_by_hir_id(id); let vec: Vec<_> = match item.node { hir::ItemKind::Trait(.., ref trait_item_refs) => { trait_item_refs.iter() .map(|trait_item_ref| trait_item_ref.id) .map(|id| tcx.hir().local_def_id_from_hir_id(id.hir_id)) .collect() } hir::ItemKind::Impl(.., ref impl_item_refs) => { impl_item_refs.iter() .map(|impl_item_ref| impl_item_ref.id) .map(|id| tcx.hir().local_def_id_from_hir_id(id.hir_id)) .collect() } hir::ItemKind::TraitAlias(..) => vec![], _ => span_bug!(item.span, "associated_item_def_ids: not impl or trait") }; Lrc::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 `DefId` describes an item belonging to a trait, /// returns the `DefId` of the trait that the trait item belongs to; /// otherwise, returns `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 } }) } /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition. pub fn is_impl_trait_defn(tcx: TyCtxt<'_, '_, '_>, def_id: DefId) -> Option { if let Some(hir_id) = tcx.hir().as_local_hir_id(def_id) { if let Node::Item(item) = tcx.hir().get_by_hir_id(hir_id) { if let hir::ItemKind::Existential(ref exist_ty) = item.node { return exist_ty.impl_trait_fn; } } } None } /// See `ParamEnv` struct definition for details. fn param_env<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> ParamEnv<'tcx> { // The param_env of an impl Trait type is its defining function's param_env if let Some(parent) = is_impl_trait_defn(tcx, def_id) { return param_env(tcx, parent); } // Compute the bounds on Self and the type parameters. let InstantiatedPredicates { predicates } = tcx.predicates_of(def_id).instantiate_identity(tcx); // 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, if tcx.sess.opts.debugging_opts.chalk { Some(def_id) } else { None } ); let body_id = tcx.hir().as_local_hir_id(def_id).map_or(hir::DUMMY_HIR_ID, |id| { tcx.hir().maybe_body_owned_by_by_hir_id(id).map_or(id, |body| body.hir_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) } fn crate_disambiguator<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, crate_num: CrateNum) -> CrateDisambiguator { assert_eq!(crate_num, LOCAL_CRATE); tcx.sess.local_crate_disambiguator() } fn original_crate_name<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, crate_num: CrateNum) -> Symbol { assert_eq!(crate_num, LOCAL_CRATE); tcx.crate_name.clone() } fn crate_hash<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, crate_num: CrateNum) -> Svh { assert_eq!(crate_num, LOCAL_CRATE); tcx.hir().crate_hash } fn instance_def_size_estimate<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, instance_def: InstanceDef<'tcx>) -> usize { match instance_def { InstanceDef::Item(..) | InstanceDef::DropGlue(..) => { let mir = tcx.instance_mir(instance_def); mir.basic_blocks().iter().map(|bb| bb.statements.len()).sum() }, // Estimate the size of other compiler-generated shims to be 1. _ => 1 } } /// If `def_id` is an issue 33140 hack impl, returns its self type; otherwise, returns `None`. /// /// See [`ImplOverlapKind::Issue33140`] for more details. fn issue33140_self_ty<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Option> { debug!("issue33140_self_ty({:?})", def_id); let trait_ref = tcx.impl_trait_ref(def_id).unwrap_or_else(|| { bug!("issue33140_self_ty called on inherent impl {:?}", def_id) }); debug!("issue33140_self_ty({:?}), trait-ref={:?}", def_id, trait_ref); let is_marker_like = tcx.impl_polarity(def_id) == hir::ImplPolarity::Positive && tcx.associated_item_def_ids(trait_ref.def_id).is_empty(); // Check whether these impls would be ok for a marker trait. if !is_marker_like { debug!("issue33140_self_ty - not marker-like!"); return None; } // impl must be `impl Trait for dyn Marker1 + Marker2 + ...` if trait_ref.substs.len() != 1 { debug!("issue33140_self_ty - impl has substs!"); return None; } let predicates = tcx.predicates_of(def_id); if predicates.parent.is_some() || !predicates.predicates.is_empty() { debug!("issue33140_self_ty - impl has predicates {:?}!", predicates); return None; } let self_ty = trait_ref.self_ty(); let self_ty_matches = match self_ty.sty { ty::Dynamic(ref data, ty::ReStatic) => data.principal().is_none(), _ => false }; if self_ty_matches { debug!("issue33140_self_ty - MATCHES!"); Some(self_ty) } else { debug!("issue33140_self_ty - non-matching self type"); None } } pub fn provide(providers: &mut ty::query::Providers<'_>) { context::provide(providers); erase_regions::provide(providers); layout::provide(providers); util::provide(providers); constness::provide(providers); *providers = ty::query::Providers { associated_item, associated_item_def_ids, adt_sized_constraint, def_span, param_env, trait_of_item, crate_disambiguator, original_crate_name, crate_hash, trait_impls_of: trait_def::trait_impls_of_provider, instance_def_size_estimate, issue33140_self_ty, ..*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: DefIdMap>>, } #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, RustcEncodable, RustcDecodable)] pub struct SymbolName { // FIXME: we don't rely on interning or equality here - better have // this be a `&'tcx str`. pub name: InternedString } impl_stable_hash_for!(struct self::SymbolName { name }); impl SymbolName { pub fn new(name: &str) -> SymbolName { SymbolName { name: Symbol::intern(name).as_interned_str() } } pub fn as_str(&self) -> LocalInternedString { self.name.as_str() } } impl fmt::Display for SymbolName { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Display::fmt(&self.name, fmt) } } impl fmt::Debug for SymbolName { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Display::fmt(&self.name, fmt) } }