1 //! Defines how the compiler represents types internally.
3 //! Two important entities in this module are:
5 //! - [`rustc_middle::ty::Ty`], used to represent the semantics of a type.
6 //! - [`rustc_middle::ty::TyCtxt`], the central data structure in the compiler.
8 //! For more information, see ["The `ty` module: representing types"] in the ructc-dev-guide.
10 //! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html
12 // ignore-tidy-filelength
13 pub use self::fold::{TypeFoldable, TypeFolder, TypeVisitor};
14 pub use self::AssocItemContainer::*;
15 pub use self::BorrowKind::*;
16 pub use self::IntVarValue::*;
17 pub use self::Variance::*;
19 use crate::hir::exports::ExportMap;
20 use crate::hir::place::Place as HirPlace;
21 use crate::ich::StableHashingContext;
22 use crate::middle::cstore::CrateStoreDyn;
23 use crate::middle::resolve_lifetime::ObjectLifetimeDefault;
24 use crate::mir::interpret::ErrorHandled;
26 use crate::mir::GeneratorLayout;
27 use crate::traits::{self, Reveal};
29 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
30 use crate::ty::util::{Discr, IntTypeExt};
32 use rustc_attr as attr;
33 use rustc_data_structures::captures::Captures;
34 use rustc_data_structures::fingerprint::Fingerprint;
35 use rustc_data_structures::fx::FxHashMap;
36 use rustc_data_structures::fx::FxHashSet;
37 use rustc_data_structures::fx::FxIndexMap;
38 use rustc_data_structures::sorted_map::SortedIndexMultiMap;
39 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
40 use rustc_data_structures::sync::{self, par_iter, ParallelIterator};
41 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
42 use rustc_errors::ErrorReported;
44 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Namespace, Res};
45 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX};
46 use rustc_hir::lang_items::LangItem;
47 use rustc_hir::{Constness, Node};
48 use rustc_index::vec::{Idx, IndexVec};
49 use rustc_macros::HashStable;
50 use rustc_serialize::{self, Encodable, Encoder};
51 use rustc_session::DataTypeKind;
52 use rustc_span::hygiene::ExpnId;
53 use rustc_span::symbol::{kw, sym, Ident, Symbol};
55 use rustc_target::abi::{Align, VariantIdx};
57 use std::cell::RefCell;
58 use std::cmp::Ordering;
60 use std::hash::{Hash, Hasher};
61 use std::ops::{ControlFlow, Range};
65 pub use self::sty::BoundRegionKind::*;
66 pub use self::sty::InferTy::*;
67 pub use self::sty::RegionKind;
68 pub use self::sty::RegionKind::*;
69 pub use self::sty::TyKind::*;
70 pub use self::sty::{Binder, BoundTy, BoundTyKind, BoundVar};
71 pub use self::sty::{BoundRegion, BoundRegionKind, EarlyBoundRegion, FreeRegion, Region};
72 pub use self::sty::{CanonicalPolyFnSig, FnSig, GenSig, PolyFnSig, PolyGenSig};
73 pub use self::sty::{ClosureSubsts, GeneratorSubsts, TypeAndMut, UpvarSubsts};
74 pub use self::sty::{ClosureSubstsParts, GeneratorSubstsParts};
75 pub use self::sty::{ConstVid, FloatVid, IntVid, RegionVid, TyVid};
76 pub use self::sty::{ExistentialPredicate, InferTy, ParamConst, ParamTy, ProjectionTy};
77 pub use self::sty::{ExistentialProjection, PolyExistentialProjection};
78 pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
79 pub use self::sty::{PolyTraitRef, TraitRef, TyKind};
80 pub use crate::ty::diagnostics::*;
81 pub use rustc_type_ir::{DebruijnIndex, TypeFlags, INNERMOST};
83 pub use self::binding::BindingMode;
84 pub use self::binding::BindingMode::*;
86 pub use self::context::{tls, FreeRegionInfo, TyCtxt};
87 pub use self::context::{
88 CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
89 DelaySpanBugEmitted, ResolvedOpaqueTy, UserType, UserTypeAnnotationIndex,
91 pub use self::context::{
92 CtxtInterners, GeneratorInteriorTypeCause, GlobalCtxt, Lift, TypeckResults,
95 pub use self::instance::{Instance, InstanceDef};
97 pub use self::list::List;
99 pub use self::trait_def::TraitDef;
101 pub use self::query::queries;
103 pub use self::consts::{Const, ConstInt, ConstKind, InferConst, ScalarInt};
115 pub mod inhabitedness;
117 pub mod normalize_erasing_regions;
132 mod structural_impls;
137 pub struct ResolverOutputs {
138 pub definitions: rustc_hir::definitions::Definitions,
139 pub cstore: Box<CrateStoreDyn>,
140 pub visibilities: FxHashMap<LocalDefId, Visibility>,
141 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
142 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
143 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
144 pub export_map: ExportMap<LocalDefId>,
145 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
146 /// Extern prelude entries. The value is `true` if the entry was introduced
147 /// via `extern crate` item and not `--extern` option or compiler built-in.
148 pub extern_prelude: FxHashMap<Symbol, bool>,
151 #[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable, Hash)]
152 pub enum AssocItemContainer {
153 TraitContainer(DefId),
154 ImplContainer(DefId),
157 impl AssocItemContainer {
158 /// Asserts that this is the `DefId` of an associated item declared
159 /// in a trait, and returns the trait `DefId`.
160 pub fn assert_trait(&self) -> DefId {
162 TraitContainer(id) => id,
163 _ => bug!("associated item has wrong container type: {:?}", self),
167 pub fn id(&self) -> DefId {
169 TraitContainer(id) => id,
170 ImplContainer(id) => id,
175 /// The "header" of an impl is everything outside the body: a Self type, a trait
176 /// ref (in the case of a trait impl), and a set of predicates (from the
177 /// bounds / where-clauses).
178 #[derive(Clone, Debug, TypeFoldable)]
179 pub struct ImplHeader<'tcx> {
180 pub impl_def_id: DefId,
181 pub self_ty: Ty<'tcx>,
182 pub trait_ref: Option<TraitRef<'tcx>>,
183 pub predicates: Vec<Predicate<'tcx>>,
186 #[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable)]
187 pub enum ImplPolarity {
188 /// `impl Trait for Type`
190 /// `impl !Trait for Type`
192 /// `#[rustc_reservation_impl] impl Trait for Type`
194 /// This is a "stability hack", not a real Rust feature.
195 /// See #64631 for details.
199 #[derive(Copy, Clone, Debug, PartialEq, HashStable, Eq, Hash)]
200 pub struct AssocItem {
202 #[stable_hasher(project(name))]
206 pub defaultness: hir::Defaultness,
207 pub container: AssocItemContainer,
209 /// Whether this is a method with an explicit self
210 /// as its first parameter, allowing method calls.
211 pub fn_has_self_parameter: bool,
214 #[derive(Copy, Clone, PartialEq, Debug, HashStable, Eq, Hash)]
222 pub fn namespace(&self) -> Namespace {
224 ty::AssocKind::Type => Namespace::TypeNS,
225 ty::AssocKind::Const | ty::AssocKind::Fn => Namespace::ValueNS,
229 pub fn as_def_kind(&self) -> DefKind {
231 AssocKind::Const => DefKind::AssocConst,
232 AssocKind::Fn => DefKind::AssocFn,
233 AssocKind::Type => DefKind::AssocTy,
239 pub fn signature(&self, tcx: TyCtxt<'_>) -> String {
241 ty::AssocKind::Fn => {
242 // We skip the binder here because the binder would deanonymize all
243 // late-bound regions, and we don't want method signatures to show up
244 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
245 // regions just fine, showing `fn(&MyType)`.
246 tcx.fn_sig(self.def_id).skip_binder().to_string()
248 ty::AssocKind::Type => format!("type {};", self.ident),
249 ty::AssocKind::Const => {
250 format!("const {}: {:?};", self.ident, tcx.type_of(self.def_id))
256 /// A list of `ty::AssocItem`s in definition order that allows for efficient lookup by name.
258 /// When doing lookup by name, we try to postpone hygienic comparison for as long as possible since
259 /// it is relatively expensive. Instead, items are indexed by `Symbol` and hygienic comparison is
260 /// done only on items with the same name.
261 #[derive(Debug, Clone, PartialEq, HashStable)]
262 pub struct AssociatedItems<'tcx> {
263 items: SortedIndexMultiMap<u32, Symbol, &'tcx ty::AssocItem>,
266 impl<'tcx> AssociatedItems<'tcx> {
267 /// Constructs an `AssociatedItems` map from a series of `ty::AssocItem`s in definition order.
268 pub fn new(items_in_def_order: impl IntoIterator<Item = &'tcx ty::AssocItem>) -> Self {
269 let items = items_in_def_order.into_iter().map(|item| (item.ident.name, item)).collect();
270 AssociatedItems { items }
273 /// Returns a slice of associated items in the order they were defined.
275 /// New code should avoid relying on definition order. If you need a particular associated item
276 /// for a known trait, make that trait a lang item instead of indexing this array.
277 pub fn in_definition_order(&self) -> impl '_ + Iterator<Item = &ty::AssocItem> {
278 self.items.iter().map(|(_, v)| *v)
281 pub fn len(&self) -> usize {
285 /// Returns an iterator over all associated items with the given name, ignoring hygiene.
286 pub fn filter_by_name_unhygienic(
289 ) -> impl '_ + Iterator<Item = &ty::AssocItem> {
290 self.items.get_by_key(&name).copied()
293 /// Returns an iterator over all associated items with the given name.
295 /// Multiple items may have the same name if they are in different `Namespace`s. For example,
296 /// an associated type can have the same name as a method. Use one of the `find_by_name_and_*`
297 /// methods below if you know which item you are looking for.
298 pub fn filter_by_name(
302 parent_def_id: DefId,
303 ) -> impl 'a + Iterator<Item = &'a ty::AssocItem> {
304 self.filter_by_name_unhygienic(ident.name)
305 .filter(move |item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
308 /// Returns the associated item with the given name and `AssocKind`, if one exists.
309 pub fn find_by_name_and_kind(
314 parent_def_id: DefId,
315 ) -> Option<&ty::AssocItem> {
316 self.filter_by_name_unhygienic(ident.name)
317 .filter(|item| item.kind == kind)
318 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
321 /// Returns the associated item with the given name in the given `Namespace`, if one exists.
322 pub fn find_by_name_and_namespace(
327 parent_def_id: DefId,
328 ) -> Option<&ty::AssocItem> {
329 self.filter_by_name_unhygienic(ident.name)
330 .filter(|item| item.kind.namespace() == ns)
331 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
335 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
336 pub enum Visibility {
337 /// Visible everywhere (including in other crates).
339 /// Visible only in the given crate-local module.
341 /// Not visible anywhere in the local crate. This is the visibility of private external items.
345 pub trait DefIdTree: Copy {
346 fn parent(self, id: DefId) -> Option<DefId>;
348 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
349 if descendant.krate != ancestor.krate {
353 while descendant != ancestor {
354 match self.parent(descendant) {
355 Some(parent) => descendant = parent,
356 None => return false,
363 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
364 fn parent(self, id: DefId) -> Option<DefId> {
365 self.def_key(id).parent.map(|index| DefId { index, ..id })
370 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
371 match visibility.node {
372 hir::VisibilityKind::Public => Visibility::Public,
373 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
374 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
375 // If there is no resolution, `resolve` will have already reported an error, so
376 // assume that the visibility is public to avoid reporting more privacy errors.
377 Res::Err => Visibility::Public,
378 def => Visibility::Restricted(def.def_id()),
380 hir::VisibilityKind::Inherited => {
381 Visibility::Restricted(tcx.parent_module(id).to_def_id())
386 /// Returns `true` if an item with this visibility is accessible from the given block.
387 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
388 let restriction = match self {
389 // Public items are visible everywhere.
390 Visibility::Public => return true,
391 // Private items from other crates are visible nowhere.
392 Visibility::Invisible => return false,
393 // Restricted items are visible in an arbitrary local module.
394 Visibility::Restricted(other) if other.krate != module.krate => return false,
395 Visibility::Restricted(module) => module,
398 tree.is_descendant_of(module, restriction)
401 /// Returns `true` if this visibility is at least as accessible as the given visibility
402 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
403 let vis_restriction = match vis {
404 Visibility::Public => return self == Visibility::Public,
405 Visibility::Invisible => return true,
406 Visibility::Restricted(module) => module,
409 self.is_accessible_from(vis_restriction, tree)
412 // Returns `true` if this item is visible anywhere in the local crate.
413 pub fn is_visible_locally(self) -> bool {
415 Visibility::Public => true,
416 Visibility::Restricted(def_id) => def_id.is_local(),
417 Visibility::Invisible => false,
422 #[derive(Copy, Clone, PartialEq, TyDecodable, TyEncodable, HashStable)]
424 Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
425 Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
426 Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
427 Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
430 /// The crate variances map is computed during typeck and contains the
431 /// variance of every item in the local crate. You should not use it
432 /// directly, because to do so will make your pass dependent on the
433 /// HIR of every item in the local crate. Instead, use
434 /// `tcx.variances_of()` to get the variance for a *particular*
436 #[derive(HashStable)]
437 pub struct CrateVariancesMap<'tcx> {
438 /// For each item with generics, maps to a vector of the variance
439 /// of its generics. If an item has no generics, it will have no
441 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
445 /// `a.xform(b)` combines the variance of a context with the
446 /// variance of a type with the following meaning. If we are in a
447 /// context with variance `a`, and we encounter a type argument in
448 /// a position with variance `b`, then `a.xform(b)` is the new
449 /// variance with which the argument appears.
455 /// Here, the "ambient" variance starts as covariant. `*mut T` is
456 /// invariant with respect to `T`, so the variance in which the
457 /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which
458 /// yields `Invariant`. Now, the type `Vec<T>` is covariant with
459 /// respect to its type argument `T`, and hence the variance of
460 /// the `i32` here is `Invariant.xform(Covariant)`, which results
461 /// (again) in `Invariant`.
465 /// fn(*const Vec<i32>, *mut Vec<i32)
467 /// The ambient variance is covariant. A `fn` type is
468 /// contravariant with respect to its parameters, so the variance
469 /// within which both pointer types appear is
470 /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const
471 /// T` is covariant with respect to `T`, so the variance within
472 /// which the first `Vec<i32>` appears is
473 /// `Contravariant.xform(Covariant)` or `Contravariant`. The same
474 /// is true for its `i32` argument. In the `*mut T` case, the
475 /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`,
476 /// and hence the outermost type is `Invariant` with respect to
477 /// `Vec<i32>` (and its `i32` argument).
479 /// Source: Figure 1 of "Taming the Wildcards:
480 /// Combining Definition- and Use-Site Variance" published in PLDI'11.
481 pub fn xform(self, v: ty::Variance) -> ty::Variance {
483 // Figure 1, column 1.
484 (ty::Covariant, ty::Covariant) => ty::Covariant,
485 (ty::Covariant, ty::Contravariant) => ty::Contravariant,
486 (ty::Covariant, ty::Invariant) => ty::Invariant,
487 (ty::Covariant, ty::Bivariant) => ty::Bivariant,
489 // Figure 1, column 2.
490 (ty::Contravariant, ty::Covariant) => ty::Contravariant,
491 (ty::Contravariant, ty::Contravariant) => ty::Covariant,
492 (ty::Contravariant, ty::Invariant) => ty::Invariant,
493 (ty::Contravariant, ty::Bivariant) => ty::Bivariant,
495 // Figure 1, column 3.
496 (ty::Invariant, _) => ty::Invariant,
498 // Figure 1, column 4.
499 (ty::Bivariant, _) => ty::Bivariant,
504 // Contains information needed to resolve types and (in the future) look up
505 // the types of AST nodes.
506 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
507 pub struct CReaderCacheKey {
512 #[allow(rustc::usage_of_ty_tykind)]
513 pub struct TyS<'tcx> {
514 /// This field shouldn't be used directly and may be removed in the future.
515 /// Use `TyS::kind()` instead.
517 /// This field shouldn't be used directly and may be removed in the future.
518 /// Use `TyS::flags()` instead.
521 /// This is a kind of confusing thing: it stores the smallest
524 /// (a) the binder itself captures nothing but
525 /// (b) all the late-bound things within the type are captured
526 /// by some sub-binder.
528 /// So, for a type without any late-bound things, like `u32`, this
529 /// will be *innermost*, because that is the innermost binder that
530 /// captures nothing. But for a type `&'D u32`, where `'D` is a
531 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
532 /// -- the binder itself does not capture `D`, but `D` is captured
533 /// by an inner binder.
535 /// We call this concept an "exclusive" binder `D` because all
536 /// De Bruijn indices within the type are contained within `0..D`
538 outer_exclusive_binder: ty::DebruijnIndex,
541 impl<'tcx> TyS<'tcx> {
542 /// A constructor used only for internal testing.
543 #[allow(rustc::usage_of_ty_tykind)]
544 pub fn make_for_test(
547 outer_exclusive_binder: ty::DebruijnIndex,
549 TyS { kind, flags, outer_exclusive_binder }
553 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
554 #[cfg(target_arch = "x86_64")]
555 static_assert_size!(TyS<'_>, 32);
557 impl<'tcx> Ord for TyS<'tcx> {
558 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
559 self.kind().cmp(other.kind())
563 impl<'tcx> PartialOrd for TyS<'tcx> {
564 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
565 Some(self.kind().cmp(other.kind()))
569 impl<'tcx> PartialEq for TyS<'tcx> {
571 fn eq(&self, other: &TyS<'tcx>) -> bool {
575 impl<'tcx> Eq for TyS<'tcx> {}
577 impl<'tcx> Hash for TyS<'tcx> {
578 fn hash<H: Hasher>(&self, s: &mut H) {
579 (self as *const TyS<'_>).hash(s)
583 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
584 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
588 // The other fields just provide fast access to information that is
589 // also contained in `kind`, so no need to hash them.
592 outer_exclusive_binder: _,
595 kind.hash_stable(hcx, hasher);
599 #[rustc_diagnostic_item = "Ty"]
600 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
614 pub struct UpvarPath {
615 pub hir_id: hir::HirId,
618 /// Upvars do not get their own `NodeId`. Instead, we use the pair of
619 /// the original var ID (that is, the root variable that is referenced
620 /// by the upvar) and the ID of the closure expression.
621 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable, TypeFoldable, HashStable)]
623 pub var_path: UpvarPath,
624 pub closure_expr_id: LocalDefId,
628 pub fn new(var_hir_id: hir::HirId, closure_def_id: LocalDefId) -> UpvarId {
629 UpvarId { var_path: UpvarPath { hir_id: var_hir_id }, closure_expr_id: closure_def_id }
633 #[derive(Clone, PartialEq, Debug, TyEncodable, TyDecodable, TypeFoldable, Copy, HashStable)]
634 pub enum BorrowKind {
635 /// Data must be immutable and is aliasable.
638 /// Data must be immutable but not aliasable. This kind of borrow
639 /// cannot currently be expressed by the user and is used only in
640 /// implicit closure bindings. It is needed when the closure
641 /// is borrowing or mutating a mutable referent, e.g.:
644 /// let x: &mut isize = ...;
645 /// let y = || *x += 5;
648 /// If we were to try to translate this closure into a more explicit
649 /// form, we'd encounter an error with the code as written:
652 /// struct Env { x: & &mut isize }
653 /// let x: &mut isize = ...;
654 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
655 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
658 /// This is then illegal because you cannot mutate a `&mut` found
659 /// in an aliasable location. To solve, you'd have to translate with
660 /// an `&mut` borrow:
663 /// struct Env { x: & &mut isize }
664 /// let x: &mut isize = ...;
665 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
666 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
669 /// Now the assignment to `**env.x` is legal, but creating a
670 /// mutable pointer to `x` is not because `x` is not mutable. We
671 /// could fix this by declaring `x` as `let mut x`. This is ok in
672 /// user code, if awkward, but extra weird for closures, since the
673 /// borrow is hidden.
675 /// So we introduce a "unique imm" borrow -- the referent is
676 /// immutable, but not aliasable. This solves the problem. For
677 /// simplicity, we don't give users the way to express this
678 /// borrow, it's just used when translating closures.
681 /// Data is mutable and not aliasable.
685 /// Information describing the capture of an upvar. This is computed
686 /// during `typeck`, specifically by `regionck`.
687 #[derive(PartialEq, Clone, Debug, Copy, TyEncodable, TyDecodable, TypeFoldable, HashStable)]
688 pub enum UpvarCapture<'tcx> {
689 /// Upvar is captured by value. This is always true when the
690 /// closure is labeled `move`, but can also be true in other cases
691 /// depending on inference.
693 /// If the upvar was inferred to be captured by value (e.g. `move`
694 /// was not used), then the `Span` points to a usage that
695 /// required it. There may be more than one such usage
696 /// (e.g. `|| { a; a; }`), in which case we pick an
698 ByValue(Option<Span>),
700 /// Upvar is captured by reference.
701 ByRef(UpvarBorrow<'tcx>),
704 #[derive(PartialEq, Clone, Copy, TyEncodable, TyDecodable, TypeFoldable, HashStable)]
705 pub struct UpvarBorrow<'tcx> {
706 /// The kind of borrow: by-ref upvars have access to shared
707 /// immutable borrows, which are not part of the normal language
709 pub kind: BorrowKind,
711 /// Region of the resulting reference.
712 pub region: ty::Region<'tcx>,
715 /// Given the closure DefId this map provides a map of root variables to minimum
716 /// set of `CapturedPlace`s that need to be tracked to support all captures of that closure.
717 pub type MinCaptureInformationMap<'tcx> = FxHashMap<DefId, RootVariableMinCaptureList<'tcx>>;
719 /// Part of `MinCaptureInformationMap`; Maps a root variable to the list of `CapturedPlace`.
720 /// Used to track the minimum set of `Place`s that need to be captured to support all
721 /// Places captured by the closure starting at a given root variable.
723 /// This provides a convenient and quick way of checking if a variable being used within
724 /// a closure is a capture of a local variable.
725 pub type RootVariableMinCaptureList<'tcx> = FxIndexMap<hir::HirId, MinCaptureList<'tcx>>;
727 /// Part of `MinCaptureInformationMap`; List of `CapturePlace`s.
728 pub type MinCaptureList<'tcx> = Vec<CapturedPlace<'tcx>>;
730 /// A `Place` and the corresponding `CaptureInfo`.
731 #[derive(PartialEq, Clone, Debug, TyEncodable, TyDecodable, TypeFoldable, HashStable)]
732 pub struct CapturedPlace<'tcx> {
733 pub place: HirPlace<'tcx>,
734 pub info: CaptureInfo<'tcx>,
737 /// Part of `MinCaptureInformationMap`; describes the capture kind (&, &mut, move)
738 /// for a particular capture as well as identifying the part of the source code
739 /// that triggered this capture to occur.
740 #[derive(PartialEq, Clone, Debug, Copy, TyEncodable, TyDecodable, TypeFoldable, HashStable)]
741 pub struct CaptureInfo<'tcx> {
742 /// Expr Id pointing to use that resulted in selecting the current capture kind
744 /// If the user doesn't enable feature `capture_disjoint_fields` (RFC 2229) then, it is
745 /// possible that we don't see the use of a particular place resulting in expr_id being
746 /// None. In such case we fallback on uvpars_mentioned for span.
757 /// In this example, if `capture_disjoint_fields` is **not** set, then x will be captured,
758 /// but we won't see it being used during capture analysis, since it's essentially a discard.
759 pub expr_id: Option<hir::HirId>,
761 /// Capture mode that was selected
762 pub capture_kind: UpvarCapture<'tcx>,
765 pub type UpvarListMap = FxHashMap<DefId, FxIndexMap<hir::HirId, UpvarId>>;
766 pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
768 #[derive(Clone, Copy, PartialEq, Eq)]
769 pub enum IntVarValue {
771 UintType(ast::UintTy),
774 #[derive(Clone, Copy, PartialEq, Eq)]
775 pub struct FloatVarValue(pub ast::FloatTy);
777 impl ty::EarlyBoundRegion {
778 /// Does this early bound region have a name? Early bound regions normally
779 /// always have names except when using anonymous lifetimes (`'_`).
780 pub fn has_name(&self) -> bool {
781 self.name != kw::UnderscoreLifetime
785 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
786 pub enum GenericParamDefKind {
790 object_lifetime_default: ObjectLifetimeDefault,
791 synthetic: Option<hir::SyntheticTyParamKind>,
796 impl GenericParamDefKind {
797 pub fn descr(&self) -> &'static str {
799 GenericParamDefKind::Lifetime => "lifetime",
800 GenericParamDefKind::Type { .. } => "type",
801 GenericParamDefKind::Const => "constant",
806 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
807 pub struct GenericParamDef {
812 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
813 /// on generic parameter `'a`/`T`, asserts data behind the parameter
814 /// `'a`/`T` won't be accessed during the parent type's `Drop` impl.
815 pub pure_wrt_drop: bool,
817 pub kind: GenericParamDefKind,
820 impl GenericParamDef {
821 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
822 if let GenericParamDefKind::Lifetime = self.kind {
823 ty::EarlyBoundRegion { def_id: self.def_id, index: self.index, name: self.name }
825 bug!("cannot convert a non-lifetime parameter def to an early bound region")
831 pub struct GenericParamCount {
832 pub lifetimes: usize,
837 /// Information about the formal type/lifetime parameters associated
838 /// with an item or method. Analogous to `hir::Generics`.
840 /// The ordering of parameters is the same as in `Subst` (excluding child generics):
841 /// `Self` (optionally), `Lifetime` params..., `Type` params...
842 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
843 pub struct Generics {
844 pub parent: Option<DefId>,
845 pub parent_count: usize,
846 pub params: Vec<GenericParamDef>,
848 /// Reverse map to the `index` field of each `GenericParamDef`.
849 #[stable_hasher(ignore)]
850 pub param_def_id_to_index: FxHashMap<DefId, u32>,
853 pub has_late_bound_regions: Option<Span>,
856 impl<'tcx> Generics {
857 pub fn count(&self) -> usize {
858 self.parent_count + self.params.len()
861 pub fn own_counts(&self) -> GenericParamCount {
862 // We could cache this as a property of `GenericParamCount`, but
863 // the aim is to refactor this away entirely eventually and the
864 // presence of this method will be a constant reminder.
865 let mut own_counts: GenericParamCount = Default::default();
867 for param in &self.params {
869 GenericParamDefKind::Lifetime => own_counts.lifetimes += 1,
870 GenericParamDefKind::Type { .. } => own_counts.types += 1,
871 GenericParamDefKind::Const => own_counts.consts += 1,
878 pub fn requires_monomorphization(&self, tcx: TyCtxt<'tcx>) -> bool {
879 if self.own_requires_monomorphization() {
883 if let Some(parent_def_id) = self.parent {
884 let parent = tcx.generics_of(parent_def_id);
885 parent.requires_monomorphization(tcx)
891 pub fn own_requires_monomorphization(&self) -> bool {
892 for param in &self.params {
894 GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true,
895 GenericParamDefKind::Lifetime => {}
901 /// Returns the `GenericParamDef` with the given index.
902 pub fn param_at(&'tcx self, param_index: usize, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
903 if let Some(index) = param_index.checked_sub(self.parent_count) {
906 tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?"))
907 .param_at(param_index, tcx)
911 /// Returns the `GenericParamDef` associated with this `EarlyBoundRegion`.
914 param: &EarlyBoundRegion,
916 ) -> &'tcx GenericParamDef {
917 let param = self.param_at(param.index as usize, tcx);
919 GenericParamDefKind::Lifetime => param,
920 _ => bug!("expected lifetime parameter, but found another generic parameter"),
924 /// Returns the `GenericParamDef` associated with this `ParamTy`.
925 pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
926 let param = self.param_at(param.index as usize, tcx);
928 GenericParamDefKind::Type { .. } => param,
929 _ => bug!("expected type parameter, but found another generic parameter"),
933 /// Returns the `GenericParamDef` associated with this `ParamConst`.
934 pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef {
935 let param = self.param_at(param.index as usize, tcx);
937 GenericParamDefKind::Const => param,
938 _ => bug!("expected const parameter, but found another generic parameter"),
943 /// Bounds on generics.
944 #[derive(Copy, Clone, Default, Debug, TyEncodable, TyDecodable, HashStable)]
945 pub struct GenericPredicates<'tcx> {
946 pub parent: Option<DefId>,
947 pub predicates: &'tcx [(Predicate<'tcx>, Span)],
950 impl<'tcx> GenericPredicates<'tcx> {
954 substs: SubstsRef<'tcx>,
955 ) -> InstantiatedPredicates<'tcx> {
956 let mut instantiated = InstantiatedPredicates::empty();
957 self.instantiate_into(tcx, &mut instantiated, substs);
961 pub fn instantiate_own(
964 substs: SubstsRef<'tcx>,
965 ) -> InstantiatedPredicates<'tcx> {
966 InstantiatedPredicates {
967 predicates: self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)).collect(),
968 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
975 instantiated: &mut InstantiatedPredicates<'tcx>,
976 substs: SubstsRef<'tcx>,
978 if let Some(def_id) = self.parent {
979 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
981 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)));
982 instantiated.spans.extend(self.predicates.iter().map(|(_, sp)| *sp));
985 pub fn instantiate_identity(&self, tcx: TyCtxt<'tcx>) -> InstantiatedPredicates<'tcx> {
986 let mut instantiated = InstantiatedPredicates::empty();
987 self.instantiate_identity_into(tcx, &mut instantiated);
991 fn instantiate_identity_into(
994 instantiated: &mut InstantiatedPredicates<'tcx>,
996 if let Some(def_id) = self.parent {
997 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
999 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p));
1000 instantiated.spans.extend(self.predicates.iter().map(|(_, s)| s));
1005 crate struct PredicateInner<'tcx> {
1006 kind: PredicateKind<'tcx>,
1008 /// See the comment for the corresponding field of [TyS].
1009 outer_exclusive_binder: ty::DebruijnIndex,
1012 #[cfg(target_arch = "x86_64")]
1013 static_assert_size!(PredicateInner<'_>, 48);
1015 #[derive(Clone, Copy, Lift)]
1016 pub struct Predicate<'tcx> {
1017 inner: &'tcx PredicateInner<'tcx>,
1020 impl<'tcx> PartialEq for Predicate<'tcx> {
1021 fn eq(&self, other: &Self) -> bool {
1022 // `self.kind` is always interned.
1023 ptr::eq(self.inner, other.inner)
1027 impl Hash for Predicate<'_> {
1028 fn hash<H: Hasher>(&self, s: &mut H) {
1029 (self.inner as *const PredicateInner<'_>).hash(s)
1033 impl<'tcx> Eq for Predicate<'tcx> {}
1035 impl<'tcx> Predicate<'tcx> {
1037 pub fn kind(self) -> &'tcx PredicateKind<'tcx> {
1041 /// Returns the inner `PredicateAtom`.
1043 /// The returned atom may contain unbound variables bound to binders skipped in this method.
1044 /// It is safe to reapply binders to the given atom.
1046 /// Note that this method panics in case this predicate has unbound variables.
1047 pub fn skip_binders(self) -> PredicateAtom<'tcx> {
1049 &PredicateKind::ForAll(binder) => binder.skip_binder(),
1050 &PredicateKind::Atom(atom) => {
1051 debug_assert!(!atom.has_escaping_bound_vars());
1057 /// Returns the inner `PredicateAtom`.
1059 /// Note that this method does not check if the predicate has unbound variables.
1061 /// Rebinding the returned atom can causes the previously bound variables
1062 /// to end up at the wrong binding level.
1063 pub fn skip_binders_unchecked(self) -> PredicateAtom<'tcx> {
1065 &PredicateKind::ForAll(binder) => binder.skip_binder(),
1066 &PredicateKind::Atom(atom) => atom,
1070 /// Converts this to a `Binder<PredicateAtom<'tcx>>`. If the value was an
1071 /// `Atom`, then it is not allowed to contain escaping bound vars.
1072 pub fn bound_atom(self) -> Binder<PredicateAtom<'tcx>> {
1074 &PredicateKind::ForAll(binder) => binder,
1075 &PredicateKind::Atom(atom) => {
1076 debug_assert!(!atom.has_escaping_bound_vars());
1082 /// Allows using a `Binder<PredicateAtom<'tcx>>` even if the given predicate previously
1083 /// contained unbound variables by shifting these variables outwards.
1084 pub fn bound_atom_with_opt_escaping(self, tcx: TyCtxt<'tcx>) -> Binder<PredicateAtom<'tcx>> {
1086 &PredicateKind::ForAll(binder) => binder,
1087 &PredicateKind::Atom(atom) => Binder::wrap_nonbinding(tcx, atom),
1092 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
1093 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1094 let PredicateInner {
1097 // The other fields just provide fast access to information that is
1098 // also contained in `kind`, so no need to hash them.
1100 outer_exclusive_binder: _,
1103 kind.hash_stable(hcx, hasher);
1107 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1108 #[derive(HashStable, TypeFoldable)]
1109 pub enum PredicateKind<'tcx> {
1111 ForAll(Binder<PredicateAtom<'tcx>>),
1112 Atom(PredicateAtom<'tcx>),
1115 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1116 #[derive(HashStable, TypeFoldable)]
1117 pub enum PredicateAtom<'tcx> {
1118 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
1119 /// the `Self` type of the trait reference and `A`, `B`, and `C`
1120 /// would be the type parameters.
1122 /// A trait predicate will have `Constness::Const` if it originates
1123 /// from a bound on a `const fn` without the `?const` opt-out (e.g.,
1124 /// `const fn foobar<Foo: Bar>() {}`).
1125 Trait(TraitPredicate<'tcx>, Constness),
1128 RegionOutlives(RegionOutlivesPredicate<'tcx>),
1131 TypeOutlives(TypeOutlivesPredicate<'tcx>),
1133 /// `where <T as TraitRef>::Name == X`, approximately.
1134 /// See the `ProjectionPredicate` struct for details.
1135 Projection(ProjectionPredicate<'tcx>),
1137 /// No syntax: `T` well-formed.
1138 WellFormed(GenericArg<'tcx>),
1140 /// Trait must be object-safe.
1143 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
1144 /// for some substitutions `...` and `T` being a closure type.
1145 /// Satisfied (or refuted) once we know the closure's kind.
1146 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
1149 Subtype(SubtypePredicate<'tcx>),
1151 /// Constant initializer must evaluate successfully.
1152 ConstEvaluatable(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>),
1154 /// Constants must be equal. The first component is the const that is expected.
1155 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
1157 /// Represents a type found in the environment that we can use for implied bounds.
1159 /// Only used for Chalk.
1160 TypeWellFormedFromEnv(Ty<'tcx>),
1163 impl<'tcx> Binder<PredicateAtom<'tcx>> {
1164 /// Wraps `self` with the given qualifier if this predicate has any unbound variables.
1165 pub fn potentially_quantified(
1168 qualifier: impl FnOnce(Binder<PredicateAtom<'tcx>>) -> PredicateKind<'tcx>,
1169 ) -> Predicate<'tcx> {
1170 match self.no_bound_vars() {
1171 Some(atom) => PredicateKind::Atom(atom),
1172 None => qualifier(self),
1178 /// The crate outlives map is computed during typeck and contains the
1179 /// outlives of every item in the local crate. You should not use it
1180 /// directly, because to do so will make your pass dependent on the
1181 /// HIR of every item in the local crate. Instead, use
1182 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
1184 #[derive(HashStable)]
1185 pub struct CratePredicatesMap<'tcx> {
1186 /// For each struct with outlive bounds, maps to a vector of the
1187 /// predicate of its outlive bounds. If an item has no outlives
1188 /// bounds, it will have no entry.
1189 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
1192 impl<'tcx> Predicate<'tcx> {
1193 /// Performs a substitution suitable for going from a
1194 /// poly-trait-ref to supertraits that must hold if that
1195 /// poly-trait-ref holds. This is slightly different from a normal
1196 /// substitution in terms of what happens with bound regions. See
1197 /// lengthy comment below for details.
1198 pub fn subst_supertrait(
1201 trait_ref: &ty::PolyTraitRef<'tcx>,
1202 ) -> Predicate<'tcx> {
1203 // The interaction between HRTB and supertraits is not entirely
1204 // obvious. Let me walk you (and myself) through an example.
1206 // Let's start with an easy case. Consider two traits:
1208 // trait Foo<'a>: Bar<'a,'a> { }
1209 // trait Bar<'b,'c> { }
1211 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
1212 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
1213 // knew that `Foo<'x>` (for any 'x) then we also know that
1214 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
1215 // normal substitution.
1217 // In terms of why this is sound, the idea is that whenever there
1218 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
1219 // holds. So if there is an impl of `T:Foo<'a>` that applies to
1220 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
1223 // Another example to be careful of is this:
1225 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
1226 // trait Bar1<'b,'c> { }
1228 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
1229 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
1230 // reason is similar to the previous example: any impl of
1231 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
1232 // basically we would want to collapse the bound lifetimes from
1233 // the input (`trait_ref`) and the supertraits.
1235 // To achieve this in practice is fairly straightforward. Let's
1236 // consider the more complicated scenario:
1238 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
1239 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
1240 // where both `'x` and `'b` would have a DB index of 1.
1241 // The substitution from the input trait-ref is therefore going to be
1242 // `'a => 'x` (where `'x` has a DB index of 1).
1243 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1244 // early-bound parameter and `'b' is a late-bound parameter with a
1246 // - If we replace `'a` with `'x` from the input, it too will have
1247 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1248 // just as we wanted.
1250 // There is only one catch. If we just apply the substitution `'a
1251 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1252 // adjust the DB index because we substituting into a binder (it
1253 // tries to be so smart...) resulting in `for<'x> for<'b>
1254 // Bar1<'x,'b>` (we have no syntax for this, so use your
1255 // imagination). Basically the 'x will have DB index of 2 and 'b
1256 // will have DB index of 1. Not quite what we want. So we apply
1257 // the substitution to the *contents* of the trait reference,
1258 // rather than the trait reference itself (put another way, the
1259 // substitution code expects equal binding levels in the values
1260 // from the substitution and the value being substituted into, and
1261 // this trick achieves that).
1262 let substs = trait_ref.skip_binder().substs;
1263 let pred = self.skip_binders();
1264 let new = pred.subst(tcx, substs);
1266 ty::Binder::bind(new).potentially_quantified(tcx, PredicateKind::ForAll)
1273 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1274 #[derive(HashStable, TypeFoldable)]
1275 pub struct TraitPredicate<'tcx> {
1276 pub trait_ref: TraitRef<'tcx>,
1279 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1281 impl<'tcx> TraitPredicate<'tcx> {
1282 pub fn def_id(self) -> DefId {
1283 self.trait_ref.def_id
1286 pub fn self_ty(self) -> Ty<'tcx> {
1287 self.trait_ref.self_ty()
1291 impl<'tcx> PolyTraitPredicate<'tcx> {
1292 pub fn def_id(self) -> DefId {
1293 // Ok to skip binder since trait `DefId` does not care about regions.
1294 self.skip_binder().def_id()
1297 pub fn self_ty(self) -> ty::Binder<Ty<'tcx>> {
1298 self.map_bound(|trait_ref| trait_ref.self_ty())
1302 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1303 #[derive(HashStable, TypeFoldable)]
1304 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
1305 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
1306 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1307 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>;
1308 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>;
1310 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
1311 #[derive(HashStable, TypeFoldable)]
1312 pub struct SubtypePredicate<'tcx> {
1313 pub a_is_expected: bool,
1317 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1319 /// This kind of predicate has no *direct* correspondent in the
1320 /// syntax, but it roughly corresponds to the syntactic forms:
1322 /// 1. `T: TraitRef<..., Item = Type>`
1323 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1325 /// In particular, form #1 is "desugared" to the combination of a
1326 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1327 /// predicates. Form #2 is a broader form in that it also permits
1328 /// equality between arbitrary types. Processing an instance of
1329 /// Form #2 eventually yields one of these `ProjectionPredicate`
1330 /// instances to normalize the LHS.
1331 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1332 #[derive(HashStable, TypeFoldable)]
1333 pub struct ProjectionPredicate<'tcx> {
1334 pub projection_ty: ProjectionTy<'tcx>,
1338 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1340 impl<'tcx> PolyProjectionPredicate<'tcx> {
1341 /// Returns the `DefId` of the associated item being projected.
1342 pub fn item_def_id(&self) -> DefId {
1343 self.skip_binder().projection_ty.item_def_id
1347 pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
1348 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1349 // `self.0.trait_ref` is permitted to have escaping regions.
1350 // This is because here `self` has a `Binder` and so does our
1351 // return value, so we are preserving the number of binding
1353 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1356 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1357 self.map_bound(|predicate| predicate.ty)
1360 /// The `DefId` of the `TraitItem` for the associated type.
1362 /// Note that this is not the `DefId` of the `TraitRef` containing this
1363 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1364 pub fn projection_def_id(&self) -> DefId {
1365 // Ok to skip binder since trait `DefId` does not care about regions.
1366 self.skip_binder().projection_ty.item_def_id
1370 pub trait ToPolyTraitRef<'tcx> {
1371 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1374 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1375 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1376 ty::Binder::dummy(*self)
1380 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1381 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1382 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1386 pub trait ToPredicate<'tcx> {
1387 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
1390 impl ToPredicate<'tcx> for PredicateKind<'tcx> {
1392 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1393 tcx.mk_predicate(self)
1397 impl ToPredicate<'tcx> for PredicateAtom<'tcx> {
1399 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1400 debug_assert!(!self.has_escaping_bound_vars(), "escaping bound vars for {:?}", self);
1401 tcx.mk_predicate(PredicateKind::Atom(self))
1405 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<TraitRef<'tcx>> {
1406 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1407 PredicateAtom::Trait(ty::TraitPredicate { trait_ref: self.value }, self.constness)
1412 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> {
1413 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1415 value: self.value.map_bound(|trait_ref| ty::TraitPredicate { trait_ref }),
1416 constness: self.constness,
1422 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitPredicate<'tcx>> {
1423 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1425 .map_bound(|value| PredicateAtom::Trait(value, self.constness))
1426 .potentially_quantified(tcx, PredicateKind::ForAll)
1430 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1431 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1432 self.map_bound(|value| PredicateAtom::RegionOutlives(value))
1433 .potentially_quantified(tcx, PredicateKind::ForAll)
1437 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1438 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1439 self.map_bound(|value| PredicateAtom::TypeOutlives(value))
1440 .potentially_quantified(tcx, PredicateKind::ForAll)
1444 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1445 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1446 self.map_bound(|value| PredicateAtom::Projection(value))
1447 .potentially_quantified(tcx, PredicateKind::ForAll)
1451 impl<'tcx> Predicate<'tcx> {
1452 pub fn to_opt_poly_trait_ref(self) -> Option<ConstnessAnd<PolyTraitRef<'tcx>>> {
1453 let predicate = self.bound_atom();
1454 match predicate.skip_binder() {
1455 PredicateAtom::Trait(t, constness) => {
1456 Some(ConstnessAnd { constness, value: predicate.rebind(t.trait_ref) })
1458 PredicateAtom::Projection(..)
1459 | PredicateAtom::Subtype(..)
1460 | PredicateAtom::RegionOutlives(..)
1461 | PredicateAtom::WellFormed(..)
1462 | PredicateAtom::ObjectSafe(..)
1463 | PredicateAtom::ClosureKind(..)
1464 | PredicateAtom::TypeOutlives(..)
1465 | PredicateAtom::ConstEvaluatable(..)
1466 | PredicateAtom::ConstEquate(..)
1467 | PredicateAtom::TypeWellFormedFromEnv(..) => None,
1471 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1472 let predicate = self.bound_atom();
1473 match predicate.skip_binder() {
1474 PredicateAtom::TypeOutlives(data) => Some(predicate.rebind(data)),
1475 PredicateAtom::Trait(..)
1476 | PredicateAtom::Projection(..)
1477 | PredicateAtom::Subtype(..)
1478 | PredicateAtom::RegionOutlives(..)
1479 | PredicateAtom::WellFormed(..)
1480 | PredicateAtom::ObjectSafe(..)
1481 | PredicateAtom::ClosureKind(..)
1482 | PredicateAtom::ConstEvaluatable(..)
1483 | PredicateAtom::ConstEquate(..)
1484 | PredicateAtom::TypeWellFormedFromEnv(..) => None,
1489 /// Represents the bounds declared on a particular set of type
1490 /// parameters. Should eventually be generalized into a flag list of
1491 /// where-clauses. You can obtain a `InstantiatedPredicates` list from a
1492 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1493 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1494 /// the `GenericPredicates` are expressed in terms of the bound type
1495 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1496 /// represented a set of bounds for some particular instantiation,
1497 /// meaning that the generic parameters have been substituted with
1502 /// struct Foo<T, U: Bar<T>> { ... }
1504 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1505 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1506 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1507 /// [usize:Bar<isize>]]`.
1508 #[derive(Clone, Debug, TypeFoldable)]
1509 pub struct InstantiatedPredicates<'tcx> {
1510 pub predicates: Vec<Predicate<'tcx>>,
1511 pub spans: Vec<Span>,
1514 impl<'tcx> InstantiatedPredicates<'tcx> {
1515 pub fn empty() -> InstantiatedPredicates<'tcx> {
1516 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1519 pub fn is_empty(&self) -> bool {
1520 self.predicates.is_empty()
1524 rustc_index::newtype_index! {
1525 /// "Universes" are used during type- and trait-checking in the
1526 /// presence of `for<..>` binders to control what sets of names are
1527 /// visible. Universes are arranged into a tree: the root universe
1528 /// contains names that are always visible. Each child then adds a new
1529 /// set of names that are visible, in addition to those of its parent.
1530 /// We say that the child universe "extends" the parent universe with
1533 /// To make this more concrete, consider this program:
1537 /// fn bar<T>(x: T) {
1538 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1542 /// The struct name `Foo` is in the root universe U0. But the type
1543 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1544 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1545 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1546 /// region `'a` is in a universe U2 that extends U1, because we can
1547 /// name it inside the fn type but not outside.
1549 /// Universes are used to do type- and trait-checking around these
1550 /// "forall" binders (also called **universal quantification**). The
1551 /// idea is that when, in the body of `bar`, we refer to `T` as a
1552 /// type, we aren't referring to any type in particular, but rather a
1553 /// kind of "fresh" type that is distinct from all other types we have
1554 /// actually declared. This is called a **placeholder** type, and we
1555 /// use universes to talk about this. In other words, a type name in
1556 /// universe 0 always corresponds to some "ground" type that the user
1557 /// declared, but a type name in a non-zero universe is a placeholder
1558 /// type -- an idealized representative of "types in general" that we
1559 /// use for checking generic functions.
1560 pub struct UniverseIndex {
1562 DEBUG_FORMAT = "U{}",
1566 impl UniverseIndex {
1567 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1569 /// Returns the "next" universe index in order -- this new index
1570 /// is considered to extend all previous universes. This
1571 /// corresponds to entering a `forall` quantifier. So, for
1572 /// example, suppose we have this type in universe `U`:
1575 /// for<'a> fn(&'a u32)
1578 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1579 /// new universe that extends `U` -- in this new universe, we can
1580 /// name the region `'a`, but that region was not nameable from
1581 /// `U` because it was not in scope there.
1582 pub fn next_universe(self) -> UniverseIndex {
1583 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1586 /// Returns `true` if `self` can name a name from `other` -- in other words,
1587 /// if the set of names in `self` is a superset of those in
1588 /// `other` (`self >= other`).
1589 pub fn can_name(self, other: UniverseIndex) -> bool {
1590 self.private >= other.private
1593 /// Returns `true` if `self` cannot name some names from `other` -- in other
1594 /// words, if the set of names in `self` is a strict subset of
1595 /// those in `other` (`self < other`).
1596 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1597 self.private < other.private
1601 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1602 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1603 /// regions/types/consts within the same universe simply have an unknown relationship to one
1605 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1606 pub struct Placeholder<T> {
1607 pub universe: UniverseIndex,
1611 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1613 T: HashStable<StableHashingContext<'a>>,
1615 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1616 self.universe.hash_stable(hcx, hasher);
1617 self.name.hash_stable(hcx, hasher);
1621 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1623 pub type PlaceholderType = Placeholder<BoundVar>;
1625 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1626 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1627 pub struct BoundConst<'tcx> {
1632 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1634 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1635 /// the `DefId` of the generic parameter it instantiates.
1637 /// This is used to avoid calls to `type_of` for const arguments during typeck
1638 /// which cause cycle errors.
1643 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1644 /// // ^ const parameter
1648 /// fn foo<const M: u8>(&self) -> usize { 42 }
1649 /// // ^ const parameter
1654 /// let _b = a.foo::<{ 3 + 7 }>();
1655 /// // ^^^^^^^^^ const argument
1659 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1660 /// which `foo` is used until we know the type of `a`.
1662 /// We only know the type of `a` once we are inside of `typeck(main)`.
1663 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1664 /// requires us to evaluate the const argument.
1666 /// To evaluate that const argument we need to know its type,
1667 /// which we would get using `type_of(const_arg)`. This requires us to
1668 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1669 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1670 /// which results in a cycle.
1672 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1674 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1675 /// already resolved `foo` so we know which const parameter this argument instantiates.
1676 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1677 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1678 /// trivial to compute.
1680 /// If we now want to use that constant in a place which potentionally needs its type
1681 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1682 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1683 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1684 /// to get the type of `did`.
1685 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1686 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1687 #[derive(Hash, HashStable)]
1688 pub struct WithOptConstParam<T> {
1690 /// The `DefId` of the corresponding generic parameter in case `did` is
1691 /// a const argument.
1693 /// Note that even if `did` is a const argument, this may still be `None`.
1694 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1695 /// to potentially update `param_did` in the case it is `None`.
1696 pub const_param_did: Option<DefId>,
1699 impl<T> WithOptConstParam<T> {
1700 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1702 pub fn unknown(did: T) -> WithOptConstParam<T> {
1703 WithOptConstParam { did, const_param_did: None }
1707 impl WithOptConstParam<LocalDefId> {
1708 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1709 /// `None` otherwise.
1711 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1712 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1715 /// In case `self` is unknown but `self.did` is a const argument, this returns
1716 /// a `WithOptConstParam` with the correct `const_param_did`.
1718 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1719 if self.const_param_did.is_none() {
1720 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1721 return Some(WithOptConstParam { did: self.did, const_param_did });
1728 pub fn to_global(self) -> WithOptConstParam<DefId> {
1729 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1732 pub fn def_id_for_type_of(self) -> DefId {
1733 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1737 impl WithOptConstParam<DefId> {
1738 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1741 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1744 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1745 if let Some(param_did) = self.const_param_did {
1746 if let Some(did) = self.did.as_local() {
1747 return Some((did, param_did));
1754 pub fn expect_local(self) -> WithOptConstParam<LocalDefId> {
1755 self.as_local().unwrap()
1758 pub fn is_local(self) -> bool {
1762 pub fn def_id_for_type_of(self) -> DefId {
1763 self.const_param_did.unwrap_or(self.did)
1767 /// When type checking, we use the `ParamEnv` to track
1768 /// details about the set of where-clauses that are in scope at this
1769 /// particular point.
1770 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1771 pub struct ParamEnv<'tcx> {
1772 /// This packs both caller bounds and the reveal enum into one pointer.
1774 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1775 /// basically the set of bounds on the in-scope type parameters, translated
1776 /// into `Obligation`s, and elaborated and normalized.
1778 /// Use the `caller_bounds()` method to access.
1780 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1781 /// want `Reveal::All`.
1783 /// Note: This is packed, use the reveal() method to access it.
1784 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, traits::Reveal, true>,
1787 unsafe impl rustc_data_structures::tagged_ptr::Tag for traits::Reveal {
1788 const BITS: usize = 1;
1789 fn into_usize(self) -> usize {
1791 traits::Reveal::UserFacing => 0,
1792 traits::Reveal::All => 1,
1795 unsafe fn from_usize(ptr: usize) -> Self {
1797 0 => traits::Reveal::UserFacing,
1798 1 => traits::Reveal::All,
1799 _ => std::hint::unreachable_unchecked(),
1804 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1805 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1806 f.debug_struct("ParamEnv")
1807 .field("caller_bounds", &self.caller_bounds())
1808 .field("reveal", &self.reveal())
1813 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1814 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1815 self.caller_bounds().hash_stable(hcx, hasher);
1816 self.reveal().hash_stable(hcx, hasher);
1820 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1821 fn super_fold_with<F: ty::fold::TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1822 ParamEnv::new(self.caller_bounds().fold_with(folder), self.reveal().fold_with(folder))
1825 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1826 self.caller_bounds().visit_with(visitor)?;
1827 self.reveal().visit_with(visitor)
1831 impl<'tcx> ParamEnv<'tcx> {
1832 /// Construct a trait environment suitable for contexts where
1833 /// there are no where-clauses in scope. Hidden types (like `impl
1834 /// Trait`) are left hidden, so this is suitable for ordinary
1837 pub fn empty() -> Self {
1838 Self::new(List::empty(), Reveal::UserFacing)
1842 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1843 self.packed.pointer()
1847 pub fn reveal(self) -> traits::Reveal {
1851 /// Construct a trait environment with no where-clauses in scope
1852 /// where the values of all `impl Trait` and other hidden types
1853 /// are revealed. This is suitable for monomorphized, post-typeck
1854 /// environments like codegen or doing optimizations.
1856 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1857 /// or invoke `param_env.with_reveal_all()`.
1859 pub fn reveal_all() -> Self {
1860 Self::new(List::empty(), Reveal::All)
1863 /// Construct a trait environment with the given set of predicates.
1865 pub fn new(caller_bounds: &'tcx List<Predicate<'tcx>>, reveal: Reveal) -> Self {
1866 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, reveal) }
1869 pub fn with_user_facing(mut self) -> Self {
1870 self.packed.set_tag(Reveal::UserFacing);
1874 /// Returns a new parameter environment with the same clauses, but
1875 /// which "reveals" the true results of projections in all cases
1876 /// (even for associated types that are specializable). This is
1877 /// the desired behavior during codegen and certain other special
1878 /// contexts; normally though we want to use `Reveal::UserFacing`,
1879 /// which is the default.
1880 /// All opaque types in the caller_bounds of the `ParamEnv`
1881 /// will be normalized to their underlying types.
1882 /// See PR #65989 and issue #65918 for more details
1883 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1884 if self.packed.tag() == traits::Reveal::All {
1888 ParamEnv::new(tcx.normalize_opaque_types(self.caller_bounds()), Reveal::All)
1891 /// Returns this same environment but with no caller bounds.
1892 pub fn without_caller_bounds(self) -> Self {
1893 Self::new(List::empty(), self.reveal())
1896 /// Creates a suitable environment in which to perform trait
1897 /// queries on the given value. When type-checking, this is simply
1898 /// the pair of the environment plus value. But when reveal is set to
1899 /// All, then if `value` does not reference any type parameters, we will
1900 /// pair it with the empty environment. This improves caching and is generally
1903 /// N.B., we preserve the environment when type-checking because it
1904 /// is possible for the user to have wacky where-clauses like
1905 /// `where Box<u32>: Copy`, which are clearly never
1906 /// satisfiable. We generally want to behave as if they were true,
1907 /// although the surrounding function is never reachable.
1908 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1909 match self.reveal() {
1910 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1913 if value.is_global() {
1914 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1916 ParamEnvAnd { param_env: self, value }
1923 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1924 pub struct ConstnessAnd<T> {
1925 pub constness: Constness,
1929 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1930 // the constness of trait bounds is being propagated correctly.
1931 pub trait WithConstness: Sized {
1933 fn with_constness(self, constness: Constness) -> ConstnessAnd<Self> {
1934 ConstnessAnd { constness, value: self }
1938 fn with_const(self) -> ConstnessAnd<Self> {
1939 self.with_constness(Constness::Const)
1943 fn without_const(self) -> ConstnessAnd<Self> {
1944 self.with_constness(Constness::NotConst)
1948 impl<T> WithConstness for T {}
1950 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1951 pub struct ParamEnvAnd<'tcx, T> {
1952 pub param_env: ParamEnv<'tcx>,
1956 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1957 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1958 (self.param_env, self.value)
1962 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1964 T: HashStable<StableHashingContext<'a>>,
1966 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1967 let ParamEnvAnd { ref param_env, ref value } = *self;
1969 param_env.hash_stable(hcx, hasher);
1970 value.hash_stable(hcx, hasher);
1974 #[derive(Copy, Clone, Debug, HashStable)]
1975 pub struct Destructor {
1976 /// The `DefId` of the destructor method
1981 #[derive(HashStable)]
1982 pub struct AdtFlags: u32 {
1983 const NO_ADT_FLAGS = 0;
1984 /// Indicates whether the ADT is an enum.
1985 const IS_ENUM = 1 << 0;
1986 /// Indicates whether the ADT is a union.
1987 const IS_UNION = 1 << 1;
1988 /// Indicates whether the ADT is a struct.
1989 const IS_STRUCT = 1 << 2;
1990 /// Indicates whether the ADT is a struct and has a constructor.
1991 const HAS_CTOR = 1 << 3;
1992 /// Indicates whether the type is `PhantomData`.
1993 const IS_PHANTOM_DATA = 1 << 4;
1994 /// Indicates whether the type has a `#[fundamental]` attribute.
1995 const IS_FUNDAMENTAL = 1 << 5;
1996 /// Indicates whether the type is `Box`.
1997 const IS_BOX = 1 << 6;
1998 /// Indicates whether the type is `ManuallyDrop`.
1999 const IS_MANUALLY_DROP = 1 << 7;
2000 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
2001 /// (i.e., this flag is never set unless this ADT is an enum).
2002 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
2007 #[derive(HashStable)]
2008 pub struct VariantFlags: u32 {
2009 const NO_VARIANT_FLAGS = 0;
2010 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
2011 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
2012 /// Indicates whether this variant was obtained as part of recovering from
2013 /// a syntactic error. May be incomplete or bogus.
2014 const IS_RECOVERED = 1 << 1;
2018 /// Definition of a variant -- a struct's fields or a enum variant.
2019 #[derive(Debug, HashStable)]
2020 pub struct VariantDef {
2021 /// `DefId` that identifies the variant itself.
2022 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
2024 /// `DefId` that identifies the variant's constructor.
2025 /// If this variant is a struct variant, then this is `None`.
2026 pub ctor_def_id: Option<DefId>,
2027 /// Variant or struct name.
2028 #[stable_hasher(project(name))]
2030 /// Discriminant of this variant.
2031 pub discr: VariantDiscr,
2032 /// Fields of this variant.
2033 pub fields: Vec<FieldDef>,
2034 /// Type of constructor of variant.
2035 pub ctor_kind: CtorKind,
2036 /// Flags of the variant (e.g. is field list non-exhaustive)?
2037 flags: VariantFlags,
2041 /// Creates a new `VariantDef`.
2043 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
2044 /// represents an enum variant).
2046 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
2047 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
2049 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
2050 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
2051 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
2052 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
2053 /// built-in trait), and we do not want to load attributes twice.
2055 /// If someone speeds up attribute loading to not be a performance concern, they can
2056 /// remove this hack and use the constructor `DefId` everywhere.
2059 variant_did: Option<DefId>,
2060 ctor_def_id: Option<DefId>,
2061 discr: VariantDiscr,
2062 fields: Vec<FieldDef>,
2063 ctor_kind: CtorKind,
2067 is_field_list_non_exhaustive: bool,
2070 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
2071 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
2072 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
2075 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
2076 if is_field_list_non_exhaustive {
2077 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
2081 flags |= VariantFlags::IS_RECOVERED;
2085 def_id: variant_did.unwrap_or(parent_did),
2095 /// Is this field list non-exhaustive?
2097 pub fn is_field_list_non_exhaustive(&self) -> bool {
2098 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
2101 /// Was this variant obtained as part of recovering from a syntactic error?
2103 pub fn is_recovered(&self) -> bool {
2104 self.flags.intersects(VariantFlags::IS_RECOVERED)
2108 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
2109 pub enum VariantDiscr {
2110 /// Explicit value for this variant, i.e., `X = 123`.
2111 /// The `DefId` corresponds to the embedded constant.
2114 /// The previous variant's discriminant plus one.
2115 /// For efficiency reasons, the distance from the
2116 /// last `Explicit` discriminant is being stored,
2117 /// or `0` for the first variant, if it has none.
2121 #[derive(Debug, HashStable)]
2122 pub struct FieldDef {
2124 #[stable_hasher(project(name))]
2126 pub vis: Visibility,
2129 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
2131 /// These are all interned (by `alloc_adt_def`) into the global arena.
2133 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
2134 /// This is slightly wrong because `union`s are not ADTs.
2135 /// Moreover, Rust only allows recursive data types through indirection.
2137 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
2139 /// The `DefId` of the struct, enum or union item.
2141 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
2142 pub variants: IndexVec<VariantIdx, VariantDef>,
2143 /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
2145 /// Repr options provided by the user.
2146 pub repr: ReprOptions,
2149 impl PartialOrd for AdtDef {
2150 fn partial_cmp(&self, other: &AdtDef) -> Option<Ordering> {
2151 Some(self.cmp(&other))
2155 /// There should be only one AdtDef for each `did`, therefore
2156 /// it is fine to implement `Ord` only based on `did`.
2157 impl Ord for AdtDef {
2158 fn cmp(&self, other: &AdtDef) -> Ordering {
2159 self.did.cmp(&other.did)
2163 impl PartialEq for AdtDef {
2164 // `AdtDef`s are always interned, and this is part of `TyS` equality.
2166 fn eq(&self, other: &Self) -> bool {
2167 ptr::eq(self, other)
2171 impl Eq for AdtDef {}
2173 impl Hash for AdtDef {
2175 fn hash<H: Hasher>(&self, s: &mut H) {
2176 (self as *const AdtDef).hash(s)
2180 impl<S: Encoder> Encodable<S> for AdtDef {
2181 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
2186 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
2187 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
2189 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default();
2192 let hash: Fingerprint = CACHE.with(|cache| {
2193 let addr = self as *const AdtDef as usize;
2194 *cache.borrow_mut().entry(addr).or_insert_with(|| {
2195 let ty::AdtDef { did, ref variants, ref flags, ref repr } = *self;
2197 let mut hasher = StableHasher::new();
2198 did.hash_stable(hcx, &mut hasher);
2199 variants.hash_stable(hcx, &mut hasher);
2200 flags.hash_stable(hcx, &mut hasher);
2201 repr.hash_stable(hcx, &mut hasher);
2207 hash.hash_stable(hcx, hasher);
2211 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
2218 impl Into<DataTypeKind> for AdtKind {
2219 fn into(self) -> DataTypeKind {
2221 AdtKind::Struct => DataTypeKind::Struct,
2222 AdtKind::Union => DataTypeKind::Union,
2223 AdtKind::Enum => DataTypeKind::Enum,
2229 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
2230 pub struct ReprFlags: u8 {
2231 const IS_C = 1 << 0;
2232 const IS_SIMD = 1 << 1;
2233 const IS_TRANSPARENT = 1 << 2;
2234 // Internal only for now. If true, don't reorder fields.
2235 const IS_LINEAR = 1 << 3;
2236 // If true, don't expose any niche to type's context.
2237 const HIDE_NICHE = 1 << 4;
2238 // Any of these flags being set prevent field reordering optimisation.
2239 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
2240 ReprFlags::IS_SIMD.bits |
2241 ReprFlags::IS_LINEAR.bits;
2245 /// Represents the repr options provided by the user,
2246 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
2247 pub struct ReprOptions {
2248 pub int: Option<attr::IntType>,
2249 pub align: Option<Align>,
2250 pub pack: Option<Align>,
2251 pub flags: ReprFlags,
2255 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
2256 let mut flags = ReprFlags::empty();
2257 let mut size = None;
2258 let mut max_align: Option<Align> = None;
2259 let mut min_pack: Option<Align> = None;
2260 for attr in tcx.get_attrs(did).iter() {
2261 for r in attr::find_repr_attrs(&tcx.sess, attr) {
2262 flags.insert(match r {
2263 attr::ReprC => ReprFlags::IS_C,
2264 attr::ReprPacked(pack) => {
2265 let pack = Align::from_bytes(pack as u64).unwrap();
2266 min_pack = Some(if let Some(min_pack) = min_pack {
2273 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2274 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
2275 attr::ReprSimd => ReprFlags::IS_SIMD,
2276 attr::ReprInt(i) => {
2280 attr::ReprAlign(align) => {
2281 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2288 // This is here instead of layout because the choice must make it into metadata.
2289 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2290 flags.insert(ReprFlags::IS_LINEAR);
2292 ReprOptions { int: size, align: max_align, pack: min_pack, flags }
2296 pub fn simd(&self) -> bool {
2297 self.flags.contains(ReprFlags::IS_SIMD)
2300 pub fn c(&self) -> bool {
2301 self.flags.contains(ReprFlags::IS_C)
2304 pub fn packed(&self) -> bool {
2308 pub fn transparent(&self) -> bool {
2309 self.flags.contains(ReprFlags::IS_TRANSPARENT)
2312 pub fn linear(&self) -> bool {
2313 self.flags.contains(ReprFlags::IS_LINEAR)
2316 pub fn hide_niche(&self) -> bool {
2317 self.flags.contains(ReprFlags::HIDE_NICHE)
2320 /// Returns the discriminant type, given these `repr` options.
2321 /// This must only be called on enums!
2322 pub fn discr_type(&self) -> attr::IntType {
2323 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2326 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2327 /// layout" optimizations, such as representing `Foo<&T>` as a
2329 pub fn inhibit_enum_layout_opt(&self) -> bool {
2330 self.c() || self.int.is_some()
2333 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2334 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2335 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2336 if let Some(pack) = self.pack {
2337 if pack.bytes() == 1 {
2341 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2344 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2345 pub fn inhibit_union_abi_opt(&self) -> bool {
2351 /// Creates a new `AdtDef`.
2356 variants: IndexVec<VariantIdx, VariantDef>,
2359 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
2360 let mut flags = AdtFlags::NO_ADT_FLAGS;
2362 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
2363 debug!("found non-exhaustive variant list for {:?}", did);
2364 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
2367 flags |= match kind {
2368 AdtKind::Enum => AdtFlags::IS_ENUM,
2369 AdtKind::Union => AdtFlags::IS_UNION,
2370 AdtKind::Struct => AdtFlags::IS_STRUCT,
2373 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
2374 flags |= AdtFlags::HAS_CTOR;
2377 let attrs = tcx.get_attrs(did);
2378 if tcx.sess.contains_name(&attrs, sym::fundamental) {
2379 flags |= AdtFlags::IS_FUNDAMENTAL;
2381 if Some(did) == tcx.lang_items().phantom_data() {
2382 flags |= AdtFlags::IS_PHANTOM_DATA;
2384 if Some(did) == tcx.lang_items().owned_box() {
2385 flags |= AdtFlags::IS_BOX;
2387 if Some(did) == tcx.lang_items().manually_drop() {
2388 flags |= AdtFlags::IS_MANUALLY_DROP;
2391 AdtDef { did, variants, flags, repr }
2394 /// Returns `true` if this is a struct.
2396 pub fn is_struct(&self) -> bool {
2397 self.flags.contains(AdtFlags::IS_STRUCT)
2400 /// Returns `true` if this is a union.
2402 pub fn is_union(&self) -> bool {
2403 self.flags.contains(AdtFlags::IS_UNION)
2406 /// Returns `true` if this is a enum.
2408 pub fn is_enum(&self) -> bool {
2409 self.flags.contains(AdtFlags::IS_ENUM)
2412 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
2414 pub fn is_variant_list_non_exhaustive(&self) -> bool {
2415 self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
2418 /// Returns the kind of the ADT.
2420 pub fn adt_kind(&self) -> AdtKind {
2423 } else if self.is_union() {
2430 /// Returns a description of this abstract data type.
2431 pub fn descr(&self) -> &'static str {
2432 match self.adt_kind() {
2433 AdtKind::Struct => "struct",
2434 AdtKind::Union => "union",
2435 AdtKind::Enum => "enum",
2439 /// Returns a description of a variant of this abstract data type.
2441 pub fn variant_descr(&self) -> &'static str {
2442 match self.adt_kind() {
2443 AdtKind::Struct => "struct",
2444 AdtKind::Union => "union",
2445 AdtKind::Enum => "variant",
2449 /// If this function returns `true`, it implies that `is_struct` must return `true`.
2451 pub fn has_ctor(&self) -> bool {
2452 self.flags.contains(AdtFlags::HAS_CTOR)
2455 /// Returns `true` if this type is `#[fundamental]` for the purposes
2456 /// of coherence checking.
2458 pub fn is_fundamental(&self) -> bool {
2459 self.flags.contains(AdtFlags::IS_FUNDAMENTAL)
2462 /// Returns `true` if this is `PhantomData<T>`.
2464 pub fn is_phantom_data(&self) -> bool {
2465 self.flags.contains(AdtFlags::IS_PHANTOM_DATA)
2468 /// Returns `true` if this is Box<T>.
2470 pub fn is_box(&self) -> bool {
2471 self.flags.contains(AdtFlags::IS_BOX)
2474 /// Returns `true` if this is `ManuallyDrop<T>`.
2476 pub fn is_manually_drop(&self) -> bool {
2477 self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
2480 /// Returns `true` if this type has a destructor.
2481 pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
2482 self.destructor(tcx).is_some()
2485 /// Asserts this is a struct or union and returns its unique variant.
2486 pub fn non_enum_variant(&self) -> &VariantDef {
2487 assert!(self.is_struct() || self.is_union());
2488 &self.variants[VariantIdx::new(0)]
2492 pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
2493 tcx.predicates_of(self.did)
2496 /// Returns an iterator over all fields contained
2499 pub fn all_fields(&self) -> impl Iterator<Item = &FieldDef> + Clone {
2500 self.variants.iter().flat_map(|v| v.fields.iter())
2503 /// Whether the ADT lacks fields. Note that this includes uninhabited enums,
2504 /// e.g., `enum Void {}` is considered payload free as well.
2505 pub fn is_payloadfree(&self) -> bool {
2506 self.variants.iter().all(|v| v.fields.is_empty())
2509 /// Return a `VariantDef` given a variant id.
2510 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
2511 self.variants.iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
2514 /// Return a `VariantDef` given a constructor id.
2515 pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
2518 .find(|v| v.ctor_def_id == Some(cid))
2519 .expect("variant_with_ctor_id: unknown variant")
2522 /// Return the index of `VariantDef` given a variant id.
2523 pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
2526 .find(|(_, v)| v.def_id == vid)
2527 .expect("variant_index_with_id: unknown variant")
2531 /// Return the index of `VariantDef` given a constructor id.
2532 pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
2535 .find(|(_, v)| v.ctor_def_id == Some(cid))
2536 .expect("variant_index_with_ctor_id: unknown variant")
2540 pub fn variant_of_res(&self, res: Res) -> &VariantDef {
2542 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
2543 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
2544 Res::Def(DefKind::Struct, _)
2545 | Res::Def(DefKind::Union, _)
2546 | Res::Def(DefKind::TyAlias, _)
2547 | Res::Def(DefKind::AssocTy, _)
2549 | Res::SelfCtor(..) => self.non_enum_variant(),
2550 _ => bug!("unexpected res {:?} in variant_of_res", res),
2555 pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
2556 assert!(self.is_enum());
2557 let param_env = tcx.param_env(expr_did);
2558 let repr_type = self.repr.discr_type();
2559 match tcx.const_eval_poly(expr_did) {
2561 let ty = repr_type.to_ty(tcx);
2562 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
2563 trace!("discriminants: {} ({:?})", b, repr_type);
2564 Some(Discr { val: b, ty })
2566 info!("invalid enum discriminant: {:#?}", val);
2567 crate::mir::interpret::struct_error(
2568 tcx.at(tcx.def_span(expr_did)),
2569 "constant evaluation of enum discriminant resulted in non-integer",
2576 let msg = match err {
2577 ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => {
2578 "enum discriminant evaluation failed"
2580 ErrorHandled::TooGeneric => "enum discriminant depends on generics",
2582 tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg);
2589 pub fn discriminants(
2592 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
2593 assert!(self.is_enum());
2594 let repr_type = self.repr.discr_type();
2595 let initial = repr_type.initial_discriminant(tcx);
2596 let mut prev_discr = None::<Discr<'tcx>>;
2597 self.variants.iter_enumerated().map(move |(i, v)| {
2598 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
2599 if let VariantDiscr::Explicit(expr_did) = v.discr {
2600 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
2604 prev_discr = Some(discr);
2611 pub fn variant_range(&self) -> Range<VariantIdx> {
2612 VariantIdx::new(0)..VariantIdx::new(self.variants.len())
2615 /// Computes the discriminant value used by a specific variant.
2616 /// Unlike `discriminants`, this is (amortized) constant-time,
2617 /// only doing at most one query for evaluating an explicit
2618 /// discriminant (the last one before the requested variant),
2619 /// assuming there are no constant-evaluation errors there.
2621 pub fn discriminant_for_variant(
2624 variant_index: VariantIdx,
2626 assert!(self.is_enum());
2627 let (val, offset) = self.discriminant_def_for_variant(variant_index);
2628 let explicit_value = val
2629 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
2630 .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx));
2631 explicit_value.checked_add(tcx, offset as u128).0
2634 /// Yields a `DefId` for the discriminant and an offset to add to it
2635 /// Alternatively, if there is no explicit discriminant, returns the
2636 /// inferred discriminant directly.
2637 pub fn discriminant_def_for_variant(&self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
2638 assert!(!self.variants.is_empty());
2639 let mut explicit_index = variant_index.as_u32();
2642 match self.variants[VariantIdx::from_u32(explicit_index)].discr {
2643 ty::VariantDiscr::Relative(0) => {
2647 ty::VariantDiscr::Relative(distance) => {
2648 explicit_index -= distance;
2650 ty::VariantDiscr::Explicit(did) => {
2651 expr_did = Some(did);
2656 (expr_did, variant_index.as_u32() - explicit_index)
2659 pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
2660 tcx.adt_destructor(self.did)
2663 /// Returns a list of types such that `Self: Sized` if and only
2664 /// if that type is `Sized`, or `TyErr` if this type is recursive.
2666 /// Oddly enough, checking that the sized-constraint is `Sized` is
2667 /// actually more expressive than checking all members:
2668 /// the `Sized` trait is inductive, so an associated type that references
2669 /// `Self` would prevent its containing ADT from being `Sized`.
2671 /// Due to normalization being eager, this applies even if
2672 /// the associated type is behind a pointer (e.g., issue #31299).
2673 pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] {
2674 tcx.adt_sized_constraint(self.did).0
2678 impl<'tcx> FieldDef {
2679 /// Returns the type of this field. The `subst` is typically obtained
2680 /// via the second field of `TyKind::AdtDef`.
2681 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2682 tcx.type_of(self.did).subst(tcx, subst)
2686 /// Represents the various closure traits in the language. This
2687 /// will determine the type of the environment (`self`, in the
2688 /// desugaring) argument that the closure expects.
2690 /// You can get the environment type of a closure using
2691 /// `tcx.closure_env_ty()`.
2692 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
2693 #[derive(HashStable)]
2694 pub enum ClosureKind {
2695 // Warning: Ordering is significant here! The ordering is chosen
2696 // because the trait Fn is a subtrait of FnMut and so in turn, and
2697 // hence we order it so that Fn < FnMut < FnOnce.
2703 impl<'tcx> ClosureKind {
2704 // This is the initial value used when doing upvar inference.
2705 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2707 pub fn trait_did(&self, tcx: TyCtxt<'tcx>) -> DefId {
2709 ClosureKind::Fn => tcx.require_lang_item(LangItem::Fn, None),
2710 ClosureKind::FnMut => tcx.require_lang_item(LangItem::FnMut, None),
2711 ClosureKind::FnOnce => tcx.require_lang_item(LangItem::FnOnce, None),
2715 /// Returns `true` if a type that impls this closure kind
2716 /// must also implement `other`.
2717 pub fn extends(self, other: ty::ClosureKind) -> bool {
2720 (ClosureKind::Fn, ClosureKind::Fn)
2721 | (ClosureKind::Fn, ClosureKind::FnMut)
2722 | (ClosureKind::Fn, ClosureKind::FnOnce)
2723 | (ClosureKind::FnMut, ClosureKind::FnMut)
2724 | (ClosureKind::FnMut, ClosureKind::FnOnce)
2725 | (ClosureKind::FnOnce, ClosureKind::FnOnce)
2729 /// Returns the representative scalar type for this closure kind.
2730 /// See `TyS::to_opt_closure_kind` for more details.
2731 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2733 ty::ClosureKind::Fn => tcx.types.i8,
2734 ty::ClosureKind::FnMut => tcx.types.i16,
2735 ty::ClosureKind::FnOnce => tcx.types.i32,
2741 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2743 hir::Mutability::Mut => MutBorrow,
2744 hir::Mutability::Not => ImmBorrow,
2748 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2749 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2750 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2752 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2754 MutBorrow => hir::Mutability::Mut,
2755 ImmBorrow => hir::Mutability::Not,
2757 // We have no type corresponding to a unique imm borrow, so
2758 // use `&mut`. It gives all the capabilities of an `&uniq`
2759 // and hence is a safe "over approximation".
2760 UniqueImmBorrow => hir::Mutability::Mut,
2764 pub fn to_user_str(&self) -> &'static str {
2766 MutBorrow => "mutable",
2767 ImmBorrow => "immutable",
2768 UniqueImmBorrow => "uniquely immutable",
2773 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
2775 #[derive(Debug, PartialEq, Eq)]
2776 pub enum ImplOverlapKind {
2777 /// These impls are always allowed to overlap.
2779 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
2782 /// These impls are allowed to overlap, but that raises
2783 /// an issue #33140 future-compatibility warning.
2785 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2786 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2788 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2789 /// that difference, making what reduces to the following set of impls:
2793 /// impl Trait for dyn Send + Sync {}
2794 /// impl Trait for dyn Sync + Send {}
2797 /// Obviously, once we made these types be identical, that code causes a coherence
2798 /// error and a fairly big headache for us. However, luckily for us, the trait
2799 /// `Trait` used in this case is basically a marker trait, and therefore having
2800 /// overlapping impls for it is sound.
2802 /// To handle this, we basically regard the trait as a marker trait, with an additional
2803 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2804 /// it has the following restrictions:
2806 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2808 /// 2. The trait-ref of both impls must be equal.
2809 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2811 /// 4. Neither of the impls can have any where-clauses.
2813 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2817 impl<'tcx> TyCtxt<'tcx> {
2818 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
2819 self.typeck(self.hir().body_owner_def_id(body))
2822 /// Returns an iterator of the `DefId`s for all body-owners in this
2823 /// crate. If you would prefer to iterate over the bodies
2824 /// themselves, you can do `self.hir().krate().body_ids.iter()`.
2825 pub fn body_owners(self) -> impl Iterator<Item = LocalDefId> + Captures<'tcx> + 'tcx {
2830 .map(move |&body_id| self.hir().body_owner_def_id(body_id))
2833 pub fn par_body_owners<F: Fn(LocalDefId) + sync::Sync + sync::Send>(self, f: F) {
2834 par_iter(&self.hir().krate().body_ids)
2835 .for_each(|&body_id| f(self.hir().body_owner_def_id(body_id)));
2838 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
2839 self.associated_items(id)
2840 .in_definition_order()
2841 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
2844 fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
2845 self.hir().get_if_local(def_id).and_then(|node| node.ident())
2848 fn item_name_from_def_id(self, def_id: DefId) -> Option<Symbol> {
2849 if def_id.index == CRATE_DEF_INDEX {
2850 Some(self.original_crate_name(def_id.krate))
2852 let def_key = self.def_key(def_id);
2853 match def_key.disambiguated_data.data {
2854 // The name of a constructor is that of its parent.
2855 rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId {
2856 krate: def_id.krate,
2857 index: def_key.parent.unwrap(),
2859 _ => def_key.disambiguated_data.data.get_opt_name(),
2864 /// Look up the name of an item across crates. This does not look at HIR.
2866 /// When possible, this function should be used for cross-crate lookups over
2867 /// [`opt_item_name`] to avoid invalidating the incremental cache. If you
2868 /// need to handle items without a name, or HIR items that will not be
2869 /// serialized cross-crate, or if you need the span of the item, use
2870 /// [`opt_item_name`] instead.
2872 /// [`opt_item_name`]: Self::opt_item_name
2873 pub fn item_name(self, id: DefId) -> Symbol {
2874 // Look at cross-crate items first to avoid invalidating the incremental cache
2875 // unless we have to.
2876 self.item_name_from_def_id(id).unwrap_or_else(|| {
2877 bug!("item_name: no name for {:?}", self.def_path(id));
2881 /// Look up the name and span of an item or [`Node`].
2883 /// See [`item_name`][Self::item_name] for more information.
2884 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
2885 // Look at the HIR first so the span will be correct if this is a local item.
2886 self.item_name_from_hir(def_id)
2887 .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span))
2890 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2891 let is_associated_item = if let Some(def_id) = def_id.as_local() {
2893 self.hir().get(self.hir().local_def_id_to_hir_id(def_id)),
2894 Node::TraitItem(_) | Node::ImplItem(_)
2898 self.def_kind(def_id),
2899 DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy
2903 is_associated_item.then(|| self.associated_item(def_id))
2906 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
2907 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
2910 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2911 variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id))
2914 /// Returns `true` if the impls are the same polarity and the trait either
2915 /// has no items or is annotated `#[marker]` and prevents item overrides.
2916 pub fn impls_are_allowed_to_overlap(
2920 ) -> Option<ImplOverlapKind> {
2921 // If either trait impl references an error, they're allowed to overlap,
2922 // as one of them essentially doesn't exist.
2923 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2924 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2926 return Some(ImplOverlapKind::Permitted { marker: false });
2929 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2930 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2931 // `#[rustc_reservation_impl]` impls don't overlap with anything
2933 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2936 return Some(ImplOverlapKind::Permitted { marker: false });
2938 (ImplPolarity::Positive, ImplPolarity::Negative)
2939 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2940 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2942 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2947 (ImplPolarity::Positive, ImplPolarity::Positive)
2948 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2951 let is_marker_overlap = {
2952 let is_marker_impl = |def_id: DefId| -> bool {
2953 let trait_ref = self.impl_trait_ref(def_id);
2954 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2956 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2959 if is_marker_overlap {
2961 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2964 Some(ImplOverlapKind::Permitted { marker: true })
2966 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2967 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2968 if self_ty1 == self_ty2 {
2970 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2973 return Some(ImplOverlapKind::Issue33140);
2976 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2977 def_id1, def_id2, self_ty1, self_ty2
2983 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2988 /// Returns `ty::VariantDef` if `res` refers to a struct,
2989 /// or variant or their constructors, panics otherwise.
2990 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2992 Res::Def(DefKind::Variant, did) => {
2993 let enum_did = self.parent(did).unwrap();
2994 self.adt_def(enum_did).variant_with_id(did)
2996 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2997 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2998 let variant_did = self.parent(variant_ctor_did).unwrap();
2999 let enum_did = self.parent(variant_did).unwrap();
3000 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
3002 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
3003 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
3004 self.adt_def(struct_did).non_enum_variant()
3006 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
3010 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
3011 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
3013 ty::InstanceDef::Item(def) => self.optimized_mir_opt_const_arg(def),
3014 ty::InstanceDef::VtableShim(..)
3015 | ty::InstanceDef::ReifyShim(..)
3016 | ty::InstanceDef::Intrinsic(..)
3017 | ty::InstanceDef::FnPtrShim(..)
3018 | ty::InstanceDef::Virtual(..)
3019 | ty::InstanceDef::ClosureOnceShim { .. }
3020 | ty::InstanceDef::DropGlue(..)
3021 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
3025 /// Gets the attributes of a definition.
3026 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
3027 if let Some(did) = did.as_local() {
3028 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
3030 self.item_attrs(did)
3034 /// Determines whether an item is annotated with an attribute.
3035 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
3036 self.sess.contains_name(&self.get_attrs(did), attr)
3039 /// Returns `true` if this is an `auto trait`.
3040 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
3041 self.trait_def(trait_def_id).has_auto_impl
3044 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
3045 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
3048 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
3049 /// If it implements no trait, returns `None`.
3050 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
3051 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
3054 /// If the given defid describes a method belonging to an impl, returns the
3055 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
3056 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
3057 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
3058 TraitContainer(_) => None,
3059 ImplContainer(def_id) => Some(def_id),
3063 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
3064 /// with the name of the crate containing the impl.
3065 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
3066 if let Some(impl_did) = impl_did.as_local() {
3067 let hir_id = self.hir().local_def_id_to_hir_id(impl_did);
3068 Ok(self.hir().span(hir_id))
3070 Err(self.crate_name(impl_did.krate))
3074 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
3075 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
3076 /// definition's parent/scope to perform comparison.
3077 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
3078 // We could use `Ident::eq` here, but we deliberately don't. The name
3079 // comparison fails frequently, and we want to avoid the expensive
3080 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
3081 use_name.name == def_name.name
3085 .hygienic_eq(def_name.span.ctxt(), self.expansion_that_defined(def_parent_def_id))
3088 pub fn expansion_that_defined(self, scope: DefId) -> ExpnId {
3089 match scope.as_local() {
3090 // Parsing and expansion aren't incremental, so we don't
3091 // need to go through a query for the same-crate case.
3092 Some(scope) => self.hir().definitions().expansion_that_defined(scope),
3093 None => self.expn_that_defined(scope),
3097 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
3098 ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope));
3102 pub fn adjust_ident_and_get_scope(
3107 ) -> (Ident, DefId) {
3109 match ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope))
3111 Some(actual_expansion) => {
3112 self.hir().definitions().parent_module_of_macro_def(actual_expansion)
3114 None => self.parent_module(block).to_def_id(),
3119 pub fn is_object_safe(self, key: DefId) -> bool {
3120 self.object_safety_violations(key).is_empty()
3124 #[derive(Clone, HashStable)]
3125 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
3127 /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition.
3128 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
3129 if let Some(def_id) = def_id.as_local() {
3130 if let Node::Item(item) = tcx.hir().get(tcx.hir().local_def_id_to_hir_id(def_id)) {
3131 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
3132 return opaque_ty.impl_trait_fn;
3139 pub fn provide(providers: &mut ty::query::Providers) {
3140 context::provide(providers);
3141 erase_regions::provide(providers);
3142 layout::provide(providers);
3143 util::provide(providers);
3144 print::provide(providers);
3145 super::util::bug::provide(providers);
3146 *providers = ty::query::Providers {
3147 trait_impls_of: trait_def::trait_impls_of_provider,
3148 all_local_trait_impls: trait_def::all_local_trait_impls,
3153 /// A map for the local crate mapping each type to a vector of its
3154 /// inherent impls. This is not meant to be used outside of coherence;
3155 /// rather, you should request the vector for a specific type via
3156 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
3157 /// (constructing this map requires touching the entire crate).
3158 #[derive(Clone, Debug, Default, HashStable)]
3159 pub struct CrateInherentImpls {
3160 pub inherent_impls: DefIdMap<Vec<DefId>>,
3163 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
3164 pub struct SymbolName<'tcx> {
3165 /// `&str` gives a consistent ordering, which ensures reproducible builds.
3166 pub name: &'tcx str,
3169 impl<'tcx> SymbolName<'tcx> {
3170 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
3172 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
3177 impl<'tcx> fmt::Display for SymbolName<'tcx> {
3178 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3179 fmt::Display::fmt(&self.name, fmt)
3183 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
3184 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3185 fmt::Display::fmt(&self.name, fmt)