1 // ignore-tidy-filelength
2 pub use self::fold::{TypeFoldable, TypeFolder, TypeVisitor};
3 pub use self::AssocItemContainer::*;
4 pub use self::BorrowKind::*;
5 pub use self::IntVarValue::*;
6 pub use self::Variance::*;
8 use crate::hir::exports::ExportMap;
9 use crate::ich::StableHashingContext;
10 use crate::infer::canonical::Canonical;
11 use crate::middle::cstore::CrateStoreDyn;
12 use crate::middle::resolve_lifetime::ObjectLifetimeDefault;
13 use crate::mir::interpret::ErrorHandled;
15 use crate::mir::GeneratorLayout;
16 use crate::traits::{self, Reveal};
18 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
19 use crate::ty::util::{Discr, IntTypeExt};
21 use rustc_attr as attr;
22 use rustc_data_structures::captures::Captures;
23 use rustc_data_structures::fingerprint::Fingerprint;
24 use rustc_data_structures::fx::FxHashMap;
25 use rustc_data_structures::fx::FxHashSet;
26 use rustc_data_structures::fx::FxIndexMap;
27 use rustc_data_structures::sorted_map::SortedIndexMultiMap;
28 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
29 use rustc_data_structures::sync::{self, par_iter, ParallelIterator};
30 use rustc_errors::ErrorReported;
32 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Namespace, Res};
33 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX};
34 use rustc_hir::lang_items::{FnMutTraitLangItem, FnOnceTraitLangItem, FnTraitLangItem};
35 use rustc_hir::{Constness, Node};
36 use rustc_index::vec::{Idx, IndexVec};
37 use rustc_macros::HashStable;
38 use rustc_serialize::{self, Encodable, Encoder};
39 use rustc_session::DataTypeKind;
40 use rustc_span::hygiene::ExpnId;
41 use rustc_span::symbol::{kw, sym, Ident, Symbol};
43 use rustc_target::abi::{Align, VariantIdx};
45 use std::cell::RefCell;
46 use std::cmp::Ordering;
48 use std::hash::{Hash, Hasher};
49 use std::marker::PhantomData;
54 pub use self::sty::BoundRegion::*;
55 pub use self::sty::InferTy::*;
56 pub use self::sty::RegionKind;
57 pub use self::sty::RegionKind::*;
58 pub use self::sty::TyKind::*;
59 pub use self::sty::{Binder, BoundTy, BoundTyKind, BoundVar, DebruijnIndex, INNERMOST};
60 pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
61 pub use self::sty::{CanonicalPolyFnSig, FnSig, GenSig, PolyFnSig, PolyGenSig};
62 pub use self::sty::{ClosureSubsts, GeneratorSubsts, TypeAndMut, UpvarSubsts};
63 pub use self::sty::{ConstVid, FloatVid, IntVid, RegionVid, TyVid};
64 pub use self::sty::{ExistentialPredicate, InferTy, ParamConst, ParamTy, ProjectionTy};
65 pub use self::sty::{ExistentialProjection, PolyExistentialProjection};
66 pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
67 pub use self::sty::{PolyTraitRef, TraitRef, TyKind};
68 pub use crate::ty::diagnostics::*;
70 pub use self::binding::BindingMode;
71 pub use self::binding::BindingMode::*;
73 pub use self::context::{tls, FreeRegionInfo, TyCtxt};
74 pub use self::context::{
75 CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, ResolvedOpaqueTy,
76 UserType, UserTypeAnnotationIndex,
78 pub use self::context::{
79 CtxtInterners, GeneratorInteriorTypeCause, GlobalCtxt, Lift, TypeckResults,
82 pub use self::instance::{Instance, InstanceDef};
84 pub use self::list::List;
86 pub use self::trait_def::TraitDef;
88 pub use self::query::queries;
90 pub use self::consts::{Const, ConstInt, ConstKind, InferConst};
102 pub mod inhabitedness;
104 pub mod normalize_erasing_regions;
120 mod structural_impls;
125 pub struct ResolverOutputs {
126 pub definitions: rustc_hir::definitions::Definitions,
127 pub cstore: Box<CrateStoreDyn>,
128 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
129 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
130 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
131 pub export_map: ExportMap<LocalDefId>,
132 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
133 /// Extern prelude entries. The value is `true` if the entry was introduced
134 /// via `extern crate` item and not `--extern` option or compiler built-in.
135 pub extern_prelude: FxHashMap<Symbol, bool>,
138 #[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable, Hash)]
139 pub enum AssocItemContainer {
140 TraitContainer(DefId),
141 ImplContainer(DefId),
144 impl AssocItemContainer {
145 /// Asserts that this is the `DefId` of an associated item declared
146 /// in a trait, and returns the trait `DefId`.
147 pub fn assert_trait(&self) -> DefId {
149 TraitContainer(id) => id,
150 _ => bug!("associated item has wrong container type: {:?}", self),
154 pub fn id(&self) -> DefId {
156 TraitContainer(id) => id,
157 ImplContainer(id) => id,
162 /// The "header" of an impl is everything outside the body: a Self type, a trait
163 /// ref (in the case of a trait impl), and a set of predicates (from the
164 /// bounds / where-clauses).
165 #[derive(Clone, Debug, TypeFoldable)]
166 pub struct ImplHeader<'tcx> {
167 pub impl_def_id: DefId,
168 pub self_ty: Ty<'tcx>,
169 pub trait_ref: Option<TraitRef<'tcx>>,
170 pub predicates: Vec<Predicate<'tcx>>,
173 #[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable)]
174 pub enum ImplPolarity {
175 /// `impl Trait for Type`
177 /// `impl !Trait for Type`
179 /// `#[rustc_reservation_impl] impl Trait for Type`
181 /// This is a "stability hack", not a real Rust feature.
182 /// See #64631 for details.
186 #[derive(Copy, Clone, Debug, PartialEq, HashStable, Eq, Hash)]
187 pub struct AssocItem {
189 #[stable_hasher(project(name))]
193 pub defaultness: hir::Defaultness,
194 pub container: AssocItemContainer,
196 /// Whether this is a method with an explicit self
197 /// as its first parameter, allowing method calls.
198 pub fn_has_self_parameter: bool,
201 #[derive(Copy, Clone, PartialEq, Debug, HashStable, Eq, Hash)]
209 pub fn namespace(&self) -> Namespace {
211 ty::AssocKind::Type => Namespace::TypeNS,
212 ty::AssocKind::Const | ty::AssocKind::Fn => Namespace::ValueNS,
216 pub fn as_def_kind(&self) -> DefKind {
218 AssocKind::Const => DefKind::AssocConst,
219 AssocKind::Fn => DefKind::AssocFn,
220 AssocKind::Type => DefKind::AssocTy,
226 pub fn signature(&self, tcx: TyCtxt<'_>) -> String {
228 ty::AssocKind::Fn => {
229 // We skip the binder here because the binder would deanonymize all
230 // late-bound regions, and we don't want method signatures to show up
231 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
232 // regions just fine, showing `fn(&MyType)`.
233 tcx.fn_sig(self.def_id).skip_binder().to_string()
235 ty::AssocKind::Type => format!("type {};", self.ident),
236 ty::AssocKind::Const => {
237 format!("const {}: {:?};", self.ident, tcx.type_of(self.def_id))
243 /// A list of `ty::AssocItem`s in definition order that allows for efficient lookup by name.
245 /// When doing lookup by name, we try to postpone hygienic comparison for as long as possible since
246 /// it is relatively expensive. Instead, items are indexed by `Symbol` and hygienic comparison is
247 /// done only on items with the same name.
248 #[derive(Debug, Clone, PartialEq, HashStable)]
249 pub struct AssociatedItems<'tcx> {
250 items: SortedIndexMultiMap<u32, Symbol, &'tcx ty::AssocItem>,
253 impl<'tcx> AssociatedItems<'tcx> {
254 /// Constructs an `AssociatedItems` map from a series of `ty::AssocItem`s in definition order.
255 pub fn new(items_in_def_order: impl IntoIterator<Item = &'tcx ty::AssocItem>) -> Self {
256 let items = items_in_def_order.into_iter().map(|item| (item.ident.name, item)).collect();
257 AssociatedItems { items }
260 /// Returns a slice of associated items in the order they were defined.
262 /// New code should avoid relying on definition order. If you need a particular associated item
263 /// for a known trait, make that trait a lang item instead of indexing this array.
264 pub fn in_definition_order(&self) -> impl '_ + Iterator<Item = &ty::AssocItem> {
265 self.items.iter().map(|(_, v)| *v)
268 /// Returns an iterator over all associated items with the given name, ignoring hygiene.
269 pub fn filter_by_name_unhygienic(
272 ) -> impl '_ + Iterator<Item = &ty::AssocItem> {
273 self.items.get_by_key(&name).copied()
276 /// Returns an iterator over all associated items with the given name.
278 /// Multiple items may have the same name if they are in different `Namespace`s. For example,
279 /// an associated type can have the same name as a method. Use one of the `find_by_name_and_*`
280 /// methods below if you know which item you are looking for.
281 pub fn filter_by_name(
285 parent_def_id: DefId,
286 ) -> impl 'a + Iterator<Item = &'a ty::AssocItem> {
287 self.filter_by_name_unhygienic(ident.name)
288 .filter(move |item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
291 /// Returns the associated item with the given name and `AssocKind`, if one exists.
292 pub fn find_by_name_and_kind(
297 parent_def_id: DefId,
298 ) -> Option<&ty::AssocItem> {
299 self.filter_by_name_unhygienic(ident.name)
300 .filter(|item| item.kind == kind)
301 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
304 /// Returns the associated item with the given name in the given `Namespace`, if one exists.
305 pub fn find_by_name_and_namespace(
310 parent_def_id: DefId,
311 ) -> Option<&ty::AssocItem> {
312 self.filter_by_name_unhygienic(ident.name)
313 .filter(|item| item.kind.namespace() == ns)
314 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
318 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
319 pub enum Visibility {
320 /// Visible everywhere (including in other crates).
322 /// Visible only in the given crate-local module.
324 /// Not visible anywhere in the local crate. This is the visibility of private external items.
328 pub trait DefIdTree: Copy {
329 fn parent(self, id: DefId) -> Option<DefId>;
331 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
332 if descendant.krate != ancestor.krate {
336 while descendant != ancestor {
337 match self.parent(descendant) {
338 Some(parent) => descendant = parent,
339 None => return false,
346 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
347 fn parent(self, id: DefId) -> Option<DefId> {
348 self.def_key(id).parent.map(|index| DefId { index, ..id })
353 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
354 match visibility.node {
355 hir::VisibilityKind::Public => Visibility::Public,
356 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
357 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
358 // If there is no resolution, `resolve` will have already reported an error, so
359 // assume that the visibility is public to avoid reporting more privacy errors.
360 Res::Err => Visibility::Public,
361 def => Visibility::Restricted(def.def_id()),
363 hir::VisibilityKind::Inherited => {
364 Visibility::Restricted(tcx.parent_module(id).to_def_id())
369 /// Returns `true` if an item with this visibility is accessible from the given block.
370 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
371 let restriction = match self {
372 // Public items are visible everywhere.
373 Visibility::Public => return true,
374 // Private items from other crates are visible nowhere.
375 Visibility::Invisible => return false,
376 // Restricted items are visible in an arbitrary local module.
377 Visibility::Restricted(other) if other.krate != module.krate => return false,
378 Visibility::Restricted(module) => module,
381 tree.is_descendant_of(module, restriction)
384 /// Returns `true` if this visibility is at least as accessible as the given visibility
385 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
386 let vis_restriction = match vis {
387 Visibility::Public => return self == Visibility::Public,
388 Visibility::Invisible => return true,
389 Visibility::Restricted(module) => module,
392 self.is_accessible_from(vis_restriction, tree)
395 // Returns `true` if this item is visible anywhere in the local crate.
396 pub fn is_visible_locally(self) -> bool {
398 Visibility::Public => true,
399 Visibility::Restricted(def_id) => def_id.is_local(),
400 Visibility::Invisible => false,
405 #[derive(Copy, Clone, PartialEq, TyDecodable, TyEncodable, HashStable)]
407 Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
408 Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
409 Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
410 Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
413 /// The crate variances map is computed during typeck and contains the
414 /// variance of every item in the local crate. You should not use it
415 /// directly, because to do so will make your pass dependent on the
416 /// HIR of every item in the local crate. Instead, use
417 /// `tcx.variances_of()` to get the variance for a *particular*
419 #[derive(HashStable)]
420 pub struct CrateVariancesMap<'tcx> {
421 /// For each item with generics, maps to a vector of the variance
422 /// of its generics. If an item has no generics, it will have no
424 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
428 /// `a.xform(b)` combines the variance of a context with the
429 /// variance of a type with the following meaning. If we are in a
430 /// context with variance `a`, and we encounter a type argument in
431 /// a position with variance `b`, then `a.xform(b)` is the new
432 /// variance with which the argument appears.
438 /// Here, the "ambient" variance starts as covariant. `*mut T` is
439 /// invariant with respect to `T`, so the variance in which the
440 /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which
441 /// yields `Invariant`. Now, the type `Vec<T>` is covariant with
442 /// respect to its type argument `T`, and hence the variance of
443 /// the `i32` here is `Invariant.xform(Covariant)`, which results
444 /// (again) in `Invariant`.
448 /// fn(*const Vec<i32>, *mut Vec<i32)
450 /// The ambient variance is covariant. A `fn` type is
451 /// contravariant with respect to its parameters, so the variance
452 /// within which both pointer types appear is
453 /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const
454 /// T` is covariant with respect to `T`, so the variance within
455 /// which the first `Vec<i32>` appears is
456 /// `Contravariant.xform(Covariant)` or `Contravariant`. The same
457 /// is true for its `i32` argument. In the `*mut T` case, the
458 /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`,
459 /// and hence the outermost type is `Invariant` with respect to
460 /// `Vec<i32>` (and its `i32` argument).
462 /// Source: Figure 1 of "Taming the Wildcards:
463 /// Combining Definition- and Use-Site Variance" published in PLDI'11.
464 pub fn xform(self, v: ty::Variance) -> ty::Variance {
466 // Figure 1, column 1.
467 (ty::Covariant, ty::Covariant) => ty::Covariant,
468 (ty::Covariant, ty::Contravariant) => ty::Contravariant,
469 (ty::Covariant, ty::Invariant) => ty::Invariant,
470 (ty::Covariant, ty::Bivariant) => ty::Bivariant,
472 // Figure 1, column 2.
473 (ty::Contravariant, ty::Covariant) => ty::Contravariant,
474 (ty::Contravariant, ty::Contravariant) => ty::Covariant,
475 (ty::Contravariant, ty::Invariant) => ty::Invariant,
476 (ty::Contravariant, ty::Bivariant) => ty::Bivariant,
478 // Figure 1, column 3.
479 (ty::Invariant, _) => ty::Invariant,
481 // Figure 1, column 4.
482 (ty::Bivariant, _) => ty::Bivariant,
487 // Contains information needed to resolve types and (in the future) look up
488 // the types of AST nodes.
489 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
490 pub struct CReaderCacheKey {
496 /// Flags that we track on types. These flags are propagated upwards
497 /// through the type during type construction, so that we can quickly check
498 /// whether the type has various kinds of types in it without recursing
499 /// over the type itself.
500 pub struct TypeFlags: u32 {
501 // Does this have parameters? Used to determine whether substitution is
503 /// Does this have [Param]?
504 const HAS_TY_PARAM = 1 << 0;
505 /// Does this have [ReEarlyBound]?
506 const HAS_RE_PARAM = 1 << 1;
507 /// Does this have [ConstKind::Param]?
508 const HAS_CT_PARAM = 1 << 2;
510 const NEEDS_SUBST = TypeFlags::HAS_TY_PARAM.bits
511 | TypeFlags::HAS_RE_PARAM.bits
512 | TypeFlags::HAS_CT_PARAM.bits;
514 /// Does this have [Infer]?
515 const HAS_TY_INFER = 1 << 3;
516 /// Does this have [ReVar]?
517 const HAS_RE_INFER = 1 << 4;
518 /// Does this have [ConstKind::Infer]?
519 const HAS_CT_INFER = 1 << 5;
521 /// Does this have inference variables? Used to determine whether
522 /// inference is required.
523 const NEEDS_INFER = TypeFlags::HAS_TY_INFER.bits
524 | TypeFlags::HAS_RE_INFER.bits
525 | TypeFlags::HAS_CT_INFER.bits;
527 /// Does this have [Placeholder]?
528 const HAS_TY_PLACEHOLDER = 1 << 6;
529 /// Does this have [RePlaceholder]?
530 const HAS_RE_PLACEHOLDER = 1 << 7;
531 /// Does this have [ConstKind::Placeholder]?
532 const HAS_CT_PLACEHOLDER = 1 << 8;
534 /// `true` if there are "names" of regions and so forth
535 /// that are local to a particular fn/inferctxt
536 const HAS_FREE_LOCAL_REGIONS = 1 << 9;
538 /// `true` if there are "names" of types and regions and so forth
539 /// that are local to a particular fn
540 const HAS_FREE_LOCAL_NAMES = TypeFlags::HAS_TY_PARAM.bits
541 | TypeFlags::HAS_CT_PARAM.bits
542 | TypeFlags::HAS_TY_INFER.bits
543 | TypeFlags::HAS_CT_INFER.bits
544 | TypeFlags::HAS_TY_PLACEHOLDER.bits
545 | TypeFlags::HAS_CT_PLACEHOLDER.bits
546 | TypeFlags::HAS_FREE_LOCAL_REGIONS.bits;
548 /// Does this have [Projection]?
549 const HAS_TY_PROJECTION = 1 << 10;
550 /// Does this have [Opaque]?
551 const HAS_TY_OPAQUE = 1 << 11;
552 /// Does this have [ConstKind::Unevaluated]?
553 const HAS_CT_PROJECTION = 1 << 12;
555 /// Could this type be normalized further?
556 const HAS_PROJECTION = TypeFlags::HAS_TY_PROJECTION.bits
557 | TypeFlags::HAS_TY_OPAQUE.bits
558 | TypeFlags::HAS_CT_PROJECTION.bits;
560 /// Is an error type/const reachable?
561 const HAS_ERROR = 1 << 13;
563 /// Does this have any region that "appears free" in the type?
564 /// Basically anything but [ReLateBound] and [ReErased].
565 const HAS_FREE_REGIONS = 1 << 14;
567 /// Does this have any [ReLateBound] regions? Used to check
568 /// if a global bound is safe to evaluate.
569 const HAS_RE_LATE_BOUND = 1 << 15;
571 /// Does this have any [ReErased] regions?
572 const HAS_RE_ERASED = 1 << 16;
574 /// Does this value have parameters/placeholders/inference variables which could be
575 /// replaced later, in a way that would change the results of `impl` specialization?
576 const STILL_FURTHER_SPECIALIZABLE = 1 << 17;
580 #[allow(rustc::usage_of_ty_tykind)]
581 pub struct TyS<'tcx> {
582 pub kind: TyKind<'tcx>,
583 pub flags: TypeFlags,
585 /// This is a kind of confusing thing: it stores the smallest
588 /// (a) the binder itself captures nothing but
589 /// (b) all the late-bound things within the type are captured
590 /// by some sub-binder.
592 /// So, for a type without any late-bound things, like `u32`, this
593 /// will be *innermost*, because that is the innermost binder that
594 /// captures nothing. But for a type `&'D u32`, where `'D` is a
595 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
596 /// -- the binder itself does not capture `D`, but `D` is captured
597 /// by an inner binder.
599 /// We call this concept an "exclusive" binder `D` because all
600 /// De Bruijn indices within the type are contained within `0..D`
602 outer_exclusive_binder: ty::DebruijnIndex,
605 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
606 #[cfg(target_arch = "x86_64")]
607 static_assert_size!(TyS<'_>, 32);
609 impl<'tcx> Ord for TyS<'tcx> {
610 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
611 self.kind.cmp(&other.kind)
615 impl<'tcx> PartialOrd for TyS<'tcx> {
616 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
617 Some(self.kind.cmp(&other.kind))
621 impl<'tcx> PartialEq for TyS<'tcx> {
623 fn eq(&self, other: &TyS<'tcx>) -> bool {
627 impl<'tcx> Eq for TyS<'tcx> {}
629 impl<'tcx> Hash for TyS<'tcx> {
630 fn hash<H: Hasher>(&self, s: &mut H) {
631 (self as *const TyS<'_>).hash(s)
635 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
636 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
640 // The other fields just provide fast access to information that is
641 // also contained in `kind`, so no need to hash them.
644 outer_exclusive_binder: _,
647 kind.hash_stable(hcx, hasher);
651 #[rustc_diagnostic_item = "Ty"]
652 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
654 pub type CanonicalTy<'tcx> = Canonical<'tcx, Ty<'tcx>>;
656 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)]
657 pub struct UpvarPath {
658 pub hir_id: hir::HirId,
661 /// Upvars do not get their own `NodeId`. Instead, we use the pair of
662 /// the original var ID (that is, the root variable that is referenced
663 /// by the upvar) and the ID of the closure expression.
664 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable)]
666 pub var_path: UpvarPath,
667 pub closure_expr_id: LocalDefId,
670 #[derive(Clone, PartialEq, Debug, TyEncodable, TyDecodable, Copy, HashStable)]
671 pub enum BorrowKind {
672 /// Data must be immutable and is aliasable.
675 /// Data must be immutable but not aliasable. This kind of borrow
676 /// cannot currently be expressed by the user and is used only in
677 /// implicit closure bindings. It is needed when the closure
678 /// is borrowing or mutating a mutable referent, e.g.:
680 /// let x: &mut isize = ...;
681 /// let y = || *x += 5;
683 /// If we were to try to translate this closure into a more explicit
684 /// form, we'd encounter an error with the code as written:
686 /// struct Env { x: & &mut isize }
687 /// let x: &mut isize = ...;
688 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
689 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
691 /// This is then illegal because you cannot mutate a `&mut` found
692 /// in an aliasable location. To solve, you'd have to translate with
693 /// an `&mut` borrow:
695 /// struct Env { x: & &mut isize }
696 /// let x: &mut isize = ...;
697 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
698 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
700 /// Now the assignment to `**env.x` is legal, but creating a
701 /// mutable pointer to `x` is not because `x` is not mutable. We
702 /// could fix this by declaring `x` as `let mut x`. This is ok in
703 /// user code, if awkward, but extra weird for closures, since the
704 /// borrow is hidden.
706 /// So we introduce a "unique imm" borrow -- the referent is
707 /// immutable, but not aliasable. This solves the problem. For
708 /// simplicity, we don't give users the way to express this
709 /// borrow, it's just used when translating closures.
712 /// Data is mutable and not aliasable.
716 /// Information describing the capture of an upvar. This is computed
717 /// during `typeck`, specifically by `regionck`.
718 #[derive(PartialEq, Clone, Debug, Copy, TyEncodable, TyDecodable, HashStable)]
719 pub enum UpvarCapture<'tcx> {
720 /// Upvar is captured by value. This is always true when the
721 /// closure is labeled `move`, but can also be true in other cases
722 /// depending on inference.
725 /// Upvar is captured by reference.
726 ByRef(UpvarBorrow<'tcx>),
729 #[derive(PartialEq, Clone, Copy, TyEncodable, TyDecodable, HashStable)]
730 pub struct UpvarBorrow<'tcx> {
731 /// The kind of borrow: by-ref upvars have access to shared
732 /// immutable borrows, which are not part of the normal language
734 pub kind: BorrowKind,
736 /// Region of the resulting reference.
737 pub region: ty::Region<'tcx>,
740 pub type UpvarListMap = FxHashMap<DefId, FxIndexMap<hir::HirId, UpvarId>>;
741 pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
743 #[derive(Clone, Copy, PartialEq, Eq)]
744 pub enum IntVarValue {
746 UintType(ast::UintTy),
749 #[derive(Clone, Copy, PartialEq, Eq)]
750 pub struct FloatVarValue(pub ast::FloatTy);
752 impl ty::EarlyBoundRegion {
753 pub fn to_bound_region(&self) -> ty::BoundRegion {
754 ty::BoundRegion::BrNamed(self.def_id, self.name)
757 /// Does this early bound region have a name? Early bound regions normally
758 /// always have names except when using anonymous lifetimes (`'_`).
759 pub fn has_name(&self) -> bool {
760 self.name != kw::UnderscoreLifetime
764 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
765 pub enum GenericParamDefKind {
769 object_lifetime_default: ObjectLifetimeDefault,
770 synthetic: Option<hir::SyntheticTyParamKind>,
775 impl GenericParamDefKind {
776 pub fn descr(&self) -> &'static str {
778 GenericParamDefKind::Lifetime => "lifetime",
779 GenericParamDefKind::Type { .. } => "type",
780 GenericParamDefKind::Const => "constant",
785 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
786 pub struct GenericParamDef {
791 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
792 /// on generic parameter `'a`/`T`, asserts data behind the parameter
793 /// `'a`/`T` won't be accessed during the parent type's `Drop` impl.
794 pub pure_wrt_drop: bool,
796 pub kind: GenericParamDefKind,
799 impl GenericParamDef {
800 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
801 if let GenericParamDefKind::Lifetime = self.kind {
802 ty::EarlyBoundRegion { def_id: self.def_id, index: self.index, name: self.name }
804 bug!("cannot convert a non-lifetime parameter def to an early bound region")
808 pub fn to_bound_region(&self) -> ty::BoundRegion {
809 if let GenericParamDefKind::Lifetime = self.kind {
810 self.to_early_bound_region_data().to_bound_region()
812 bug!("cannot convert a non-lifetime parameter def to an early bound region")
818 pub struct GenericParamCount {
819 pub lifetimes: usize,
824 /// Information about the formal type/lifetime parameters associated
825 /// with an item or method. Analogous to `hir::Generics`.
827 /// The ordering of parameters is the same as in `Subst` (excluding child generics):
828 /// `Self` (optionally), `Lifetime` params..., `Type` params...
829 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
830 pub struct Generics {
831 pub parent: Option<DefId>,
832 pub parent_count: usize,
833 pub params: Vec<GenericParamDef>,
835 /// Reverse map to the `index` field of each `GenericParamDef`.
836 #[stable_hasher(ignore)]
837 pub param_def_id_to_index: FxHashMap<DefId, u32>,
840 pub has_late_bound_regions: Option<Span>,
843 impl<'tcx> Generics {
844 pub fn count(&self) -> usize {
845 self.parent_count + self.params.len()
848 pub fn own_counts(&self) -> GenericParamCount {
849 // We could cache this as a property of `GenericParamCount`, but
850 // the aim is to refactor this away entirely eventually and the
851 // presence of this method will be a constant reminder.
852 let mut own_counts: GenericParamCount = Default::default();
854 for param in &self.params {
856 GenericParamDefKind::Lifetime => own_counts.lifetimes += 1,
857 GenericParamDefKind::Type { .. } => own_counts.types += 1,
858 GenericParamDefKind::Const => own_counts.consts += 1,
865 pub fn requires_monomorphization(&self, tcx: TyCtxt<'tcx>) -> bool {
866 if self.own_requires_monomorphization() {
870 if let Some(parent_def_id) = self.parent {
871 let parent = tcx.generics_of(parent_def_id);
872 parent.requires_monomorphization(tcx)
878 pub fn own_requires_monomorphization(&self) -> bool {
879 for param in &self.params {
881 GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true,
882 GenericParamDefKind::Lifetime => {}
888 /// Returns the `GenericParamDef` with the given index.
889 pub fn param_at(&'tcx self, param_index: usize, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
890 if let Some(index) = param_index.checked_sub(self.parent_count) {
893 tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?"))
894 .param_at(param_index, tcx)
898 /// Returns the `GenericParamDef` associated with this `EarlyBoundRegion`.
901 param: &EarlyBoundRegion,
903 ) -> &'tcx GenericParamDef {
904 let param = self.param_at(param.index as usize, tcx);
906 GenericParamDefKind::Lifetime => param,
907 _ => bug!("expected lifetime parameter, but found another generic parameter"),
911 /// Returns the `GenericParamDef` associated with this `ParamTy`.
912 pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
913 let param = self.param_at(param.index as usize, tcx);
915 GenericParamDefKind::Type { .. } => param,
916 _ => bug!("expected type parameter, but found another generic parameter"),
920 /// Returns the `GenericParamDef` associated with this `ParamConst`.
921 pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef {
922 let param = self.param_at(param.index as usize, tcx);
924 GenericParamDefKind::Const => param,
925 _ => bug!("expected const parameter, but found another generic parameter"),
930 /// Bounds on generics.
931 #[derive(Copy, Clone, Default, Debug, TyEncodable, TyDecodable, HashStable)]
932 pub struct GenericPredicates<'tcx> {
933 pub parent: Option<DefId>,
934 pub predicates: &'tcx [(Predicate<'tcx>, Span)],
937 impl<'tcx> GenericPredicates<'tcx> {
941 substs: SubstsRef<'tcx>,
942 ) -> InstantiatedPredicates<'tcx> {
943 let mut instantiated = InstantiatedPredicates::empty();
944 self.instantiate_into(tcx, &mut instantiated, substs);
948 pub fn instantiate_own(
951 substs: SubstsRef<'tcx>,
952 ) -> InstantiatedPredicates<'tcx> {
953 InstantiatedPredicates {
954 predicates: self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)).collect(),
955 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
962 instantiated: &mut InstantiatedPredicates<'tcx>,
963 substs: SubstsRef<'tcx>,
965 if let Some(def_id) = self.parent {
966 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
968 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)));
969 instantiated.spans.extend(self.predicates.iter().map(|(_, sp)| *sp));
972 pub fn instantiate_identity(&self, tcx: TyCtxt<'tcx>) -> InstantiatedPredicates<'tcx> {
973 let mut instantiated = InstantiatedPredicates::empty();
974 self.instantiate_identity_into(tcx, &mut instantiated);
978 fn instantiate_identity_into(
981 instantiated: &mut InstantiatedPredicates<'tcx>,
983 if let Some(def_id) = self.parent {
984 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
986 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p));
987 instantiated.spans.extend(self.predicates.iter().map(|(_, s)| s));
990 pub fn instantiate_supertrait(
993 poly_trait_ref: &ty::PolyTraitRef<'tcx>,
994 ) -> InstantiatedPredicates<'tcx> {
995 assert_eq!(self.parent, None);
996 InstantiatedPredicates {
1000 .map(|(pred, _)| pred.subst_supertrait(tcx, poly_trait_ref))
1002 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
1008 crate struct PredicateInner<'tcx> {
1009 kind: PredicateKind<'tcx>,
1011 /// See the comment for the corresponding field of [TyS].
1012 outer_exclusive_binder: ty::DebruijnIndex,
1015 #[cfg(target_arch = "x86_64")]
1016 static_assert_size!(PredicateInner<'_>, 48);
1018 #[derive(Clone, Copy, Lift)]
1019 pub struct Predicate<'tcx> {
1020 inner: &'tcx PredicateInner<'tcx>,
1023 impl<'tcx> PartialEq for Predicate<'tcx> {
1024 fn eq(&self, other: &Self) -> bool {
1025 // `self.kind` is always interned.
1026 ptr::eq(self.inner, other.inner)
1030 impl Hash for Predicate<'_> {
1031 fn hash<H: Hasher>(&self, s: &mut H) {
1032 (self.inner as *const PredicateInner<'_>).hash(s)
1036 impl<'tcx> Eq for Predicate<'tcx> {}
1038 impl<'tcx> Predicate<'tcx> {
1040 pub fn kind(self) -> &'tcx PredicateKind<'tcx> {
1044 /// Returns the inner `PredicateAtom`.
1046 /// The returned atom may contain unbound variables bound to binders skipped in this method.
1047 /// It is safe to reapply binders to the given atom.
1049 /// Note that this method panics in case this predicate has unbound variables.
1050 pub fn skip_binders(self) -> PredicateAtom<'tcx> {
1052 &PredicateKind::ForAll(binder) => binder.skip_binder(),
1053 &PredicateKind::Atom(atom) => {
1054 debug_assert!(!atom.has_escaping_bound_vars());
1060 /// Returns the inner `PredicateAtom`.
1062 /// Note that this method does not check if the predicate has unbound variables.
1064 /// Rebinding the returned atom can causes the previously bound variables
1065 /// to end up at the wrong binding level.
1066 pub fn skip_binders_unchecked(self) -> PredicateAtom<'tcx> {
1068 &PredicateKind::ForAll(binder) => binder.skip_binder(),
1069 &PredicateKind::Atom(atom) => atom,
1073 /// Allows using a `Binder<PredicateAtom<'tcx>>` even if the given predicate previously
1074 /// contained unbound variables by shifting these variables outwards.
1075 pub fn bound_atom(self, tcx: TyCtxt<'tcx>) -> Binder<PredicateAtom<'tcx>> {
1077 &PredicateKind::ForAll(binder) => binder,
1078 &PredicateKind::Atom(atom) => Binder::wrap_nonbinding(tcx, atom),
1083 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
1084 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1085 let PredicateInner {
1088 // The other fields just provide fast access to information that is
1089 // also contained in `kind`, so no need to hash them.
1091 outer_exclusive_binder: _,
1094 kind.hash_stable(hcx, hasher);
1098 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1099 #[derive(HashStable, TypeFoldable)]
1100 pub enum PredicateKind<'tcx> {
1102 ForAll(Binder<PredicateAtom<'tcx>>),
1103 Atom(PredicateAtom<'tcx>),
1106 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1107 #[derive(HashStable, TypeFoldable)]
1108 pub enum PredicateAtom<'tcx> {
1109 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
1110 /// the `Self` type of the trait reference and `A`, `B`, and `C`
1111 /// would be the type parameters.
1113 /// A trait predicate will have `Constness::Const` if it originates
1114 /// from a bound on a `const fn` without the `?const` opt-out (e.g.,
1115 /// `const fn foobar<Foo: Bar>() {}`).
1116 Trait(TraitPredicate<'tcx>, Constness),
1119 RegionOutlives(RegionOutlivesPredicate<'tcx>),
1122 TypeOutlives(TypeOutlivesPredicate<'tcx>),
1124 /// `where <T as TraitRef>::Name == X`, approximately.
1125 /// See the `ProjectionPredicate` struct for details.
1126 Projection(ProjectionPredicate<'tcx>),
1128 /// No syntax: `T` well-formed.
1129 WellFormed(GenericArg<'tcx>),
1131 /// Trait must be object-safe.
1134 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
1135 /// for some substitutions `...` and `T` being a closure type.
1136 /// Satisfied (or refuted) once we know the closure's kind.
1137 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
1140 Subtype(SubtypePredicate<'tcx>),
1142 /// Constant initializer must evaluate successfully.
1143 ConstEvaluatable(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>),
1145 /// Constants must be equal. The first component is the const that is expected.
1146 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
1149 impl<'tcx> PredicateAtom<'tcx> {
1150 /// Wraps `self` with the given qualifier if this predicate has any unbound variables.
1151 pub fn potentially_quantified(
1154 qualifier: impl FnOnce(Binder<PredicateAtom<'tcx>>) -> PredicateKind<'tcx>,
1155 ) -> Predicate<'tcx> {
1156 if self.has_escaping_bound_vars() {
1157 qualifier(Binder::bind(self))
1159 PredicateKind::Atom(self)
1165 /// The crate outlives map is computed during typeck and contains the
1166 /// outlives of every item in the local crate. You should not use it
1167 /// directly, because to do so will make your pass dependent on the
1168 /// HIR of every item in the local crate. Instead, use
1169 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
1171 #[derive(HashStable)]
1172 pub struct CratePredicatesMap<'tcx> {
1173 /// For each struct with outlive bounds, maps to a vector of the
1174 /// predicate of its outlive bounds. If an item has no outlives
1175 /// bounds, it will have no entry.
1176 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
1179 impl<'tcx> Predicate<'tcx> {
1180 /// Performs a substitution suitable for going from a
1181 /// poly-trait-ref to supertraits that must hold if that
1182 /// poly-trait-ref holds. This is slightly different from a normal
1183 /// substitution in terms of what happens with bound regions. See
1184 /// lengthy comment below for details.
1185 pub fn subst_supertrait(
1188 trait_ref: &ty::PolyTraitRef<'tcx>,
1189 ) -> Predicate<'tcx> {
1190 // The interaction between HRTB and supertraits is not entirely
1191 // obvious. Let me walk you (and myself) through an example.
1193 // Let's start with an easy case. Consider two traits:
1195 // trait Foo<'a>: Bar<'a,'a> { }
1196 // trait Bar<'b,'c> { }
1198 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
1199 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
1200 // knew that `Foo<'x>` (for any 'x) then we also know that
1201 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
1202 // normal substitution.
1204 // In terms of why this is sound, the idea is that whenever there
1205 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
1206 // holds. So if there is an impl of `T:Foo<'a>` that applies to
1207 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
1210 // Another example to be careful of is this:
1212 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
1213 // trait Bar1<'b,'c> { }
1215 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
1216 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
1217 // reason is similar to the previous example: any impl of
1218 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
1219 // basically we would want to collapse the bound lifetimes from
1220 // the input (`trait_ref`) and the supertraits.
1222 // To achieve this in practice is fairly straightforward. Let's
1223 // consider the more complicated scenario:
1225 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
1226 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
1227 // where both `'x` and `'b` would have a DB index of 1.
1228 // The substitution from the input trait-ref is therefore going to be
1229 // `'a => 'x` (where `'x` has a DB index of 1).
1230 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1231 // early-bound parameter and `'b' is a late-bound parameter with a
1233 // - If we replace `'a` with `'x` from the input, it too will have
1234 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1235 // just as we wanted.
1237 // There is only one catch. If we just apply the substitution `'a
1238 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1239 // adjust the DB index because we substituting into a binder (it
1240 // tries to be so smart...) resulting in `for<'x> for<'b>
1241 // Bar1<'x,'b>` (we have no syntax for this, so use your
1242 // imagination). Basically the 'x will have DB index of 2 and 'b
1243 // will have DB index of 1. Not quite what we want. So we apply
1244 // the substitution to the *contents* of the trait reference,
1245 // rather than the trait reference itself (put another way, the
1246 // substitution code expects equal binding levels in the values
1247 // from the substitution and the value being substituted into, and
1248 // this trick achieves that).
1249 let substs = trait_ref.skip_binder().substs;
1250 let pred = self.skip_binders();
1251 let new = pred.subst(tcx, substs);
1252 if new != pred { new.potentially_quantified(tcx, PredicateKind::ForAll) } else { self }
1256 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1257 #[derive(HashStable, TypeFoldable)]
1258 pub struct TraitPredicate<'tcx> {
1259 pub trait_ref: TraitRef<'tcx>,
1262 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1264 impl<'tcx> TraitPredicate<'tcx> {
1265 pub fn def_id(self) -> DefId {
1266 self.trait_ref.def_id
1269 pub fn self_ty(self) -> Ty<'tcx> {
1270 self.trait_ref.self_ty()
1274 impl<'tcx> PolyTraitPredicate<'tcx> {
1275 pub fn def_id(self) -> DefId {
1276 // Ok to skip binder since trait `DefId` does not care about regions.
1277 self.skip_binder().def_id()
1281 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1282 #[derive(HashStable, TypeFoldable)]
1283 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
1284 pub type PolyOutlivesPredicate<A, B> = ty::Binder<OutlivesPredicate<A, B>>;
1285 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
1286 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1287 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>;
1288 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>;
1290 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
1291 #[derive(HashStable, TypeFoldable)]
1292 pub struct SubtypePredicate<'tcx> {
1293 pub a_is_expected: bool,
1297 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1299 /// This kind of predicate has no *direct* correspondent in the
1300 /// syntax, but it roughly corresponds to the syntactic forms:
1302 /// 1. `T: TraitRef<..., Item = Type>`
1303 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1305 /// In particular, form #1 is "desugared" to the combination of a
1306 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1307 /// predicates. Form #2 is a broader form in that it also permits
1308 /// equality between arbitrary types. Processing an instance of
1309 /// Form #2 eventually yields one of these `ProjectionPredicate`
1310 /// instances to normalize the LHS.
1311 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1312 #[derive(HashStable, TypeFoldable)]
1313 pub struct ProjectionPredicate<'tcx> {
1314 pub projection_ty: ProjectionTy<'tcx>,
1318 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1320 impl<'tcx> PolyProjectionPredicate<'tcx> {
1321 /// Returns the `DefId` of the associated item being projected.
1322 pub fn item_def_id(&self) -> DefId {
1323 self.skip_binder().projection_ty.item_def_id
1327 pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
1328 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1329 // `self.0.trait_ref` is permitted to have escaping regions.
1330 // This is because here `self` has a `Binder` and so does our
1331 // return value, so we are preserving the number of binding
1333 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1336 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1337 self.map_bound(|predicate| predicate.ty)
1340 /// The `DefId` of the `TraitItem` for the associated type.
1342 /// Note that this is not the `DefId` of the `TraitRef` containing this
1343 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1344 pub fn projection_def_id(&self) -> DefId {
1345 // Ok to skip binder since trait `DefId` does not care about regions.
1346 self.skip_binder().projection_ty.item_def_id
1350 pub trait ToPolyTraitRef<'tcx> {
1351 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1354 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1355 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1356 ty::Binder::dummy(*self)
1360 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1361 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1362 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1366 pub trait ToPredicate<'tcx> {
1367 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
1370 impl ToPredicate<'tcx> for PredicateKind<'tcx> {
1372 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1373 tcx.mk_predicate(self)
1377 impl ToPredicate<'tcx> for PredicateAtom<'tcx> {
1379 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1380 debug_assert!(!self.has_escaping_bound_vars(), "escaping bound vars for {:?}", self);
1381 tcx.mk_predicate(PredicateKind::Atom(self))
1385 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<TraitRef<'tcx>> {
1386 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1387 PredicateAtom::Trait(ty::TraitPredicate { trait_ref: self.value }, self.constness)
1392 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> {
1393 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1395 value: self.value.map_bound(|trait_ref| ty::TraitPredicate { trait_ref }),
1396 constness: self.constness,
1402 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitPredicate<'tcx>> {
1403 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1404 PredicateAtom::Trait(self.value.skip_binder(), self.constness)
1405 .potentially_quantified(tcx, PredicateKind::ForAll)
1409 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1410 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1411 PredicateAtom::RegionOutlives(self.skip_binder())
1412 .potentially_quantified(tcx, PredicateKind::ForAll)
1416 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1417 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1418 PredicateAtom::TypeOutlives(self.skip_binder())
1419 .potentially_quantified(tcx, PredicateKind::ForAll)
1423 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1424 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1425 PredicateAtom::Projection(self.skip_binder())
1426 .potentially_quantified(tcx, PredicateKind::ForAll)
1430 impl<'tcx> Predicate<'tcx> {
1431 pub fn to_opt_poly_trait_ref(self) -> Option<PolyTraitRef<'tcx>> {
1432 match self.skip_binders() {
1433 PredicateAtom::Trait(t, _) => Some(ty::Binder::bind(t.trait_ref)),
1434 PredicateAtom::Projection(..)
1435 | PredicateAtom::Subtype(..)
1436 | PredicateAtom::RegionOutlives(..)
1437 | PredicateAtom::WellFormed(..)
1438 | PredicateAtom::ObjectSafe(..)
1439 | PredicateAtom::ClosureKind(..)
1440 | PredicateAtom::TypeOutlives(..)
1441 | PredicateAtom::ConstEvaluatable(..)
1442 | PredicateAtom::ConstEquate(..) => None,
1446 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1447 match self.skip_binders() {
1448 PredicateAtom::TypeOutlives(data) => Some(ty::Binder::bind(data)),
1449 PredicateAtom::Trait(..)
1450 | PredicateAtom::Projection(..)
1451 | PredicateAtom::Subtype(..)
1452 | PredicateAtom::RegionOutlives(..)
1453 | PredicateAtom::WellFormed(..)
1454 | PredicateAtom::ObjectSafe(..)
1455 | PredicateAtom::ClosureKind(..)
1456 | PredicateAtom::ConstEvaluatable(..)
1457 | PredicateAtom::ConstEquate(..) => None,
1462 /// Represents the bounds declared on a particular set of type
1463 /// parameters. Should eventually be generalized into a flag list of
1464 /// where-clauses. You can obtain a `InstantiatedPredicates` list from a
1465 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1466 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1467 /// the `GenericPredicates` are expressed in terms of the bound type
1468 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1469 /// represented a set of bounds for some particular instantiation,
1470 /// meaning that the generic parameters have been substituted with
1475 /// struct Foo<T, U: Bar<T>> { ... }
1477 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1478 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1479 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1480 /// [usize:Bar<isize>]]`.
1481 #[derive(Clone, Debug, TypeFoldable)]
1482 pub struct InstantiatedPredicates<'tcx> {
1483 pub predicates: Vec<Predicate<'tcx>>,
1484 pub spans: Vec<Span>,
1487 impl<'tcx> InstantiatedPredicates<'tcx> {
1488 pub fn empty() -> InstantiatedPredicates<'tcx> {
1489 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1492 pub fn is_empty(&self) -> bool {
1493 self.predicates.is_empty()
1497 rustc_index::newtype_index! {
1498 /// "Universes" are used during type- and trait-checking in the
1499 /// presence of `for<..>` binders to control what sets of names are
1500 /// visible. Universes are arranged into a tree: the root universe
1501 /// contains names that are always visible. Each child then adds a new
1502 /// set of names that are visible, in addition to those of its parent.
1503 /// We say that the child universe "extends" the parent universe with
1506 /// To make this more concrete, consider this program:
1510 /// fn bar<T>(x: T) {
1511 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1515 /// The struct name `Foo` is in the root universe U0. But the type
1516 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1517 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1518 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1519 /// region `'a` is in a universe U2 that extends U1, because we can
1520 /// name it inside the fn type but not outside.
1522 /// Universes are used to do type- and trait-checking around these
1523 /// "forall" binders (also called **universal quantification**). The
1524 /// idea is that when, in the body of `bar`, we refer to `T` as a
1525 /// type, we aren't referring to any type in particular, but rather a
1526 /// kind of "fresh" type that is distinct from all other types we have
1527 /// actually declared. This is called a **placeholder** type, and we
1528 /// use universes to talk about this. In other words, a type name in
1529 /// universe 0 always corresponds to some "ground" type that the user
1530 /// declared, but a type name in a non-zero universe is a placeholder
1531 /// type -- an idealized representative of "types in general" that we
1532 /// use for checking generic functions.
1533 pub struct UniverseIndex {
1535 DEBUG_FORMAT = "U{}",
1539 impl UniverseIndex {
1540 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1542 /// Returns the "next" universe index in order -- this new index
1543 /// is considered to extend all previous universes. This
1544 /// corresponds to entering a `forall` quantifier. So, for
1545 /// example, suppose we have this type in universe `U`:
1548 /// for<'a> fn(&'a u32)
1551 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1552 /// new universe that extends `U` -- in this new universe, we can
1553 /// name the region `'a`, but that region was not nameable from
1554 /// `U` because it was not in scope there.
1555 pub fn next_universe(self) -> UniverseIndex {
1556 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1559 /// Returns `true` if `self` can name a name from `other` -- in other words,
1560 /// if the set of names in `self` is a superset of those in
1561 /// `other` (`self >= other`).
1562 pub fn can_name(self, other: UniverseIndex) -> bool {
1563 self.private >= other.private
1566 /// Returns `true` if `self` cannot name some names from `other` -- in other
1567 /// words, if the set of names in `self` is a strict subset of
1568 /// those in `other` (`self < other`).
1569 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1570 self.private < other.private
1574 /// The "placeholder index" fully defines a placeholder region.
1575 /// Placeholder regions are identified by both a **universe** as well
1576 /// as a "bound-region" within that universe. The `bound_region` is
1577 /// basically a name -- distinct bound regions within the same
1578 /// universe are just two regions with an unknown relationship to one
1580 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1581 pub struct Placeholder<T> {
1582 pub universe: UniverseIndex,
1586 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1588 T: HashStable<StableHashingContext<'a>>,
1590 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1591 self.universe.hash_stable(hcx, hasher);
1592 self.name.hash_stable(hcx, hasher);
1596 pub type PlaceholderRegion = Placeholder<BoundRegion>;
1598 pub type PlaceholderType = Placeholder<BoundVar>;
1600 pub type PlaceholderConst = Placeholder<BoundVar>;
1602 /// A `DefId` which is potentially bundled with its corresponding generic parameter
1603 /// in case `did` is a const argument.
1605 /// This is used to prevent cycle errors during typeck
1606 /// as `type_of(const_arg)` depends on `typeck(owning_body)`
1607 /// which once again requires the type of its generic arguments.
1609 /// Luckily we only need to deal with const arguments once we
1610 /// know their corresponding parameters. We (ab)use this by
1611 /// calling `type_of(param_did)` for these arguments.
1614 /// #![feature(const_generics)]
1618 /// fn foo<const N: usize>(&self) -> usize { N }
1622 /// fn foo<const N: u8>(&self) -> usize { 42 }
1630 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1631 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1632 #[derive(Hash, HashStable)]
1633 pub struct WithOptConstParam<T> {
1635 /// The `DefId` of the corresponding generic paramter in case `did` is
1636 /// a const argument.
1638 /// Note that even if `did` is a const argument, this may still be `None`.
1639 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1640 /// to potentially update `param_did` in case it `None`.
1641 pub const_param_did: Option<DefId>,
1644 impl<T> WithOptConstParam<T> {
1645 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1647 pub fn unknown(did: T) -> WithOptConstParam<T> {
1648 WithOptConstParam { did, const_param_did: None }
1652 impl WithOptConstParam<LocalDefId> {
1653 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1654 /// `None` otherwise.
1656 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1657 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1660 /// In case `self` is unknown but `self.did` is a const argument, this returns
1661 /// a `WithOptConstParam` with the correct `const_param_did`.
1663 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1664 if self.const_param_did.is_none() {
1665 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1666 return Some(WithOptConstParam { did: self.did, const_param_did });
1673 pub fn to_global(self) -> WithOptConstParam<DefId> {
1674 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1677 pub fn def_id_for_type_of(self) -> DefId {
1678 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1682 impl WithOptConstParam<DefId> {
1683 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1686 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1689 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1690 if let Some(param_did) = self.const_param_did {
1691 if let Some(did) = self.did.as_local() {
1692 return Some((did, param_did));
1699 pub fn expect_local(self) -> WithOptConstParam<LocalDefId> {
1700 self.as_local().unwrap()
1703 pub fn is_local(self) -> bool {
1707 pub fn def_id_for_type_of(self) -> DefId {
1708 self.const_param_did.unwrap_or(self.did)
1712 /// When type checking, we use the `ParamEnv` to track
1713 /// details about the set of where-clauses that are in scope at this
1714 /// particular point.
1715 #[derive(Copy, Clone)]
1716 pub struct ParamEnv<'tcx> {
1717 // We pack the caller_bounds List pointer and a Reveal enum into this usize.
1718 // Specifically, the low bit represents Reveal, with 0 meaning `UserFacing`
1719 // and 1 meaning `All`. The rest is the pointer.
1721 // This relies on the List<Predicate<'tcx>> type having at least 2-byte
1722 // alignment. Lists start with a usize and are repr(C) so this should be
1723 // fine; there is a debug_assert in the constructor as well.
1725 // Note that the choice of 0 for UserFacing is intentional -- since it is the
1726 // first variant in Reveal this means that joining the pointer is a simple `or`.
1729 /// `Obligation`s that the caller must satisfy. This is basically
1730 /// the set of bounds on the in-scope type parameters, translated
1731 /// into `Obligation`s, and elaborated and normalized.
1733 /// Note: This is packed into the `packed_data` usize above, use the
1734 /// `caller_bounds()` method to access it.
1735 caller_bounds: PhantomData<&'tcx List<Predicate<'tcx>>>,
1737 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1738 /// want `Reveal::All`.
1740 /// Note: This is packed into the caller_bounds usize above, use the reveal()
1741 /// method to access it.
1742 reveal: PhantomData<traits::Reveal>,
1744 /// If this `ParamEnv` comes from a call to `tcx.param_env(def_id)`,
1745 /// register that `def_id` (useful for transitioning to the chalk trait
1747 pub def_id: Option<DefId>,
1750 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1751 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1752 f.debug_struct("ParamEnv")
1753 .field("caller_bounds", &self.caller_bounds())
1754 .field("reveal", &self.reveal())
1755 .field("def_id", &self.def_id)
1760 impl<'tcx> Hash for ParamEnv<'tcx> {
1761 fn hash<H: Hasher>(&self, state: &mut H) {
1762 // List hashes as the raw pointer, so we can skip splitting into the
1763 // pointer and the enum.
1764 self.packed_data.hash(state);
1765 self.def_id.hash(state);
1769 impl<'tcx> PartialEq for ParamEnv<'tcx> {
1770 fn eq(&self, other: &Self) -> bool {
1771 self.caller_bounds() == other.caller_bounds()
1772 && self.reveal() == other.reveal()
1773 && self.def_id == other.def_id
1776 impl<'tcx> Eq for ParamEnv<'tcx> {}
1778 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1779 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1780 self.caller_bounds().hash_stable(hcx, hasher);
1781 self.reveal().hash_stable(hcx, hasher);
1782 self.def_id.hash_stable(hcx, hasher);
1786 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1787 fn super_fold_with<F: ty::fold::TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1789 self.caller_bounds().fold_with(folder),
1790 self.reveal().fold_with(folder),
1791 self.def_id.fold_with(folder),
1795 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1796 self.caller_bounds().visit_with(visitor)
1797 || self.reveal().visit_with(visitor)
1798 || self.def_id.visit_with(visitor)
1802 impl<'tcx> ParamEnv<'tcx> {
1803 /// Construct a trait environment suitable for contexts where
1804 /// there are no where-clauses in scope. Hidden types (like `impl
1805 /// Trait`) are left hidden, so this is suitable for ordinary
1808 pub fn empty() -> Self {
1809 Self::new(List::empty(), Reveal::UserFacing, None)
1813 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1814 // mask out bottom bit
1815 unsafe { &*((self.packed_data & (!1)) as *const _) }
1819 pub fn reveal(self) -> traits::Reveal {
1820 if self.packed_data & 1 == 0 { traits::Reveal::UserFacing } else { traits::Reveal::All }
1823 /// Construct a trait environment with no where-clauses in scope
1824 /// where the values of all `impl Trait` and other hidden types
1825 /// are revealed. This is suitable for monomorphized, post-typeck
1826 /// environments like codegen or doing optimizations.
1828 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1829 /// or invoke `param_env.with_reveal_all()`.
1831 pub fn reveal_all() -> Self {
1832 Self::new(List::empty(), Reveal::All, None)
1835 /// Construct a trait environment with the given set of predicates.
1838 caller_bounds: &'tcx List<Predicate<'tcx>>,
1840 def_id: Option<DefId>,
1842 let packed_data = caller_bounds as *const _ as usize;
1843 // Check that we can pack the reveal data into the pointer.
1844 debug_assert!(packed_data & 1 == 0);
1846 packed_data: packed_data
1848 Reveal::UserFacing => 0,
1851 caller_bounds: PhantomData,
1852 reveal: PhantomData,
1857 pub fn with_user_facing(mut self) -> Self {
1859 self.packed_data &= !1;
1863 /// Returns a new parameter environment with the same clauses, but
1864 /// which "reveals" the true results of projections in all cases
1865 /// (even for associated types that are specializable). This is
1866 /// the desired behavior during codegen and certain other special
1867 /// contexts; normally though we want to use `Reveal::UserFacing`,
1868 /// which is the default.
1869 /// All opaque types in the caller_bounds of the `ParamEnv`
1870 /// will be normalized to their underlying types.
1871 /// See PR #65989 and issue #65918 for more details
1872 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1873 if self.packed_data & 1 == 1 {
1877 ParamEnv::new(tcx.normalize_opaque_types(self.caller_bounds()), Reveal::All, self.def_id)
1880 /// Returns this same environment but with no caller bounds.
1881 pub fn without_caller_bounds(self) -> Self {
1882 Self::new(List::empty(), self.reveal(), self.def_id)
1885 /// Creates a suitable environment in which to perform trait
1886 /// queries on the given value. When type-checking, this is simply
1887 /// the pair of the environment plus value. But when reveal is set to
1888 /// All, then if `value` does not reference any type parameters, we will
1889 /// pair it with the empty environment. This improves caching and is generally
1892 /// N.B., we preserve the environment when type-checking because it
1893 /// is possible for the user to have wacky where-clauses like
1894 /// `where Box<u32>: Copy`, which are clearly never
1895 /// satisfiable. We generally want to behave as if they were true,
1896 /// although the surrounding function is never reachable.
1897 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1898 match self.reveal() {
1899 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1902 if value.is_global() {
1903 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1905 ParamEnvAnd { param_env: self, value }
1912 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1913 pub struct ConstnessAnd<T> {
1914 pub constness: Constness,
1918 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1919 // the constness of trait bounds is being propagated correctly.
1920 pub trait WithConstness: Sized {
1922 fn with_constness(self, constness: Constness) -> ConstnessAnd<Self> {
1923 ConstnessAnd { constness, value: self }
1927 fn with_const(self) -> ConstnessAnd<Self> {
1928 self.with_constness(Constness::Const)
1932 fn without_const(self) -> ConstnessAnd<Self> {
1933 self.with_constness(Constness::NotConst)
1937 impl<T> WithConstness for T {}
1939 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1940 pub struct ParamEnvAnd<'tcx, T> {
1941 pub param_env: ParamEnv<'tcx>,
1945 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1946 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1947 (self.param_env, self.value)
1951 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1953 T: HashStable<StableHashingContext<'a>>,
1955 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1956 let ParamEnvAnd { ref param_env, ref value } = *self;
1958 param_env.hash_stable(hcx, hasher);
1959 value.hash_stable(hcx, hasher);
1963 #[derive(Copy, Clone, Debug, HashStable)]
1964 pub struct Destructor {
1965 /// The `DefId` of the destructor method
1970 #[derive(HashStable)]
1971 pub struct AdtFlags: u32 {
1972 const NO_ADT_FLAGS = 0;
1973 /// Indicates whether the ADT is an enum.
1974 const IS_ENUM = 1 << 0;
1975 /// Indicates whether the ADT is a union.
1976 const IS_UNION = 1 << 1;
1977 /// Indicates whether the ADT is a struct.
1978 const IS_STRUCT = 1 << 2;
1979 /// Indicates whether the ADT is a struct and has a constructor.
1980 const HAS_CTOR = 1 << 3;
1981 /// Indicates whether the type is `PhantomData`.
1982 const IS_PHANTOM_DATA = 1 << 4;
1983 /// Indicates whether the type has a `#[fundamental]` attribute.
1984 const IS_FUNDAMENTAL = 1 << 5;
1985 /// Indicates whether the type is `Box`.
1986 const IS_BOX = 1 << 6;
1987 /// Indicates whether the type is `ManuallyDrop`.
1988 const IS_MANUALLY_DROP = 1 << 7;
1989 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
1990 /// (i.e., this flag is never set unless this ADT is an enum).
1991 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
1996 #[derive(HashStable)]
1997 pub struct VariantFlags: u32 {
1998 const NO_VARIANT_FLAGS = 0;
1999 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
2000 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
2004 /// Definition of a variant -- a struct's fields or a enum variant.
2005 #[derive(Debug, HashStable)]
2006 pub struct VariantDef {
2007 /// `DefId` that identifies the variant itself.
2008 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
2010 /// `DefId` that identifies the variant's constructor.
2011 /// If this variant is a struct variant, then this is `None`.
2012 pub ctor_def_id: Option<DefId>,
2013 /// Variant or struct name.
2014 #[stable_hasher(project(name))]
2016 /// Discriminant of this variant.
2017 pub discr: VariantDiscr,
2018 /// Fields of this variant.
2019 pub fields: Vec<FieldDef>,
2020 /// Type of constructor of variant.
2021 pub ctor_kind: CtorKind,
2022 /// Flags of the variant (e.g. is field list non-exhaustive)?
2023 flags: VariantFlags,
2024 /// Variant is obtained as part of recovering from a syntactic error.
2025 /// May be incomplete or bogus.
2026 pub recovered: bool,
2029 impl<'tcx> VariantDef {
2030 /// Creates a new `VariantDef`.
2032 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
2033 /// represents an enum variant).
2035 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
2036 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
2038 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
2039 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
2040 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
2041 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
2042 /// built-in trait), and we do not want to load attributes twice.
2044 /// If someone speeds up attribute loading to not be a performance concern, they can
2045 /// remove this hack and use the constructor `DefId` everywhere.
2048 variant_did: Option<DefId>,
2049 ctor_def_id: Option<DefId>,
2050 discr: VariantDiscr,
2051 fields: Vec<FieldDef>,
2052 ctor_kind: CtorKind,
2056 is_field_list_non_exhaustive: bool,
2059 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
2060 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
2061 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
2064 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
2065 if is_field_list_non_exhaustive {
2066 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
2070 def_id: variant_did.unwrap_or(parent_did),
2081 /// Is this field list non-exhaustive?
2083 pub fn is_field_list_non_exhaustive(&self) -> bool {
2084 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
2087 /// `repr(transparent)` structs can have a single non-ZST field, this function returns that
2089 pub fn transparent_newtype_field(&self, tcx: TyCtxt<'tcx>) -> Option<&FieldDef> {
2090 for field in &self.fields {
2091 let field_ty = field.ty(tcx, InternalSubsts::identity_for_item(tcx, self.def_id));
2092 if !field_ty.is_zst(tcx, self.def_id) {
2101 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
2102 pub enum VariantDiscr {
2103 /// Explicit value for this variant, i.e., `X = 123`.
2104 /// The `DefId` corresponds to the embedded constant.
2107 /// The previous variant's discriminant plus one.
2108 /// For efficiency reasons, the distance from the
2109 /// last `Explicit` discriminant is being stored,
2110 /// or `0` for the first variant, if it has none.
2114 #[derive(Debug, HashStable)]
2115 pub struct FieldDef {
2117 #[stable_hasher(project(name))]
2119 pub vis: Visibility,
2122 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
2124 /// These are all interned (by `alloc_adt_def`) into the global arena.
2126 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
2127 /// This is slightly wrong because `union`s are not ADTs.
2128 /// Moreover, Rust only allows recursive data types through indirection.
2130 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
2132 /// The `DefId` of the struct, enum or union item.
2134 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
2135 pub variants: IndexVec<VariantIdx, VariantDef>,
2136 /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
2138 /// Repr options provided by the user.
2139 pub repr: ReprOptions,
2142 impl PartialOrd for AdtDef {
2143 fn partial_cmp(&self, other: &AdtDef) -> Option<Ordering> {
2144 Some(self.cmp(&other))
2148 /// There should be only one AdtDef for each `did`, therefore
2149 /// it is fine to implement `Ord` only based on `did`.
2150 impl Ord for AdtDef {
2151 fn cmp(&self, other: &AdtDef) -> Ordering {
2152 self.did.cmp(&other.did)
2156 impl PartialEq for AdtDef {
2157 // `AdtDef`s are always interned, and this is part of `TyS` equality.
2159 fn eq(&self, other: &Self) -> bool {
2160 ptr::eq(self, other)
2164 impl Eq for AdtDef {}
2166 impl Hash for AdtDef {
2168 fn hash<H: Hasher>(&self, s: &mut H) {
2169 (self as *const AdtDef).hash(s)
2173 impl<S: Encoder> Encodable<S> for AdtDef {
2174 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
2179 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
2180 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
2182 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default();
2185 let hash: Fingerprint = CACHE.with(|cache| {
2186 let addr = self as *const AdtDef as usize;
2187 *cache.borrow_mut().entry(addr).or_insert_with(|| {
2188 let ty::AdtDef { did, ref variants, ref flags, ref repr } = *self;
2190 let mut hasher = StableHasher::new();
2191 did.hash_stable(hcx, &mut hasher);
2192 variants.hash_stable(hcx, &mut hasher);
2193 flags.hash_stable(hcx, &mut hasher);
2194 repr.hash_stable(hcx, &mut hasher);
2200 hash.hash_stable(hcx, hasher);
2204 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
2211 impl Into<DataTypeKind> for AdtKind {
2212 fn into(self) -> DataTypeKind {
2214 AdtKind::Struct => DataTypeKind::Struct,
2215 AdtKind::Union => DataTypeKind::Union,
2216 AdtKind::Enum => DataTypeKind::Enum,
2222 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
2223 pub struct ReprFlags: u8 {
2224 const IS_C = 1 << 0;
2225 const IS_SIMD = 1 << 1;
2226 const IS_TRANSPARENT = 1 << 2;
2227 // Internal only for now. If true, don't reorder fields.
2228 const IS_LINEAR = 1 << 3;
2229 // If true, don't expose any niche to type's context.
2230 const HIDE_NICHE = 1 << 4;
2231 // Any of these flags being set prevent field reordering optimisation.
2232 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
2233 ReprFlags::IS_SIMD.bits |
2234 ReprFlags::IS_LINEAR.bits;
2238 /// Represents the repr options provided by the user,
2239 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
2240 pub struct ReprOptions {
2241 pub int: Option<attr::IntType>,
2242 pub align: Option<Align>,
2243 pub pack: Option<Align>,
2244 pub flags: ReprFlags,
2248 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
2249 let mut flags = ReprFlags::empty();
2250 let mut size = None;
2251 let mut max_align: Option<Align> = None;
2252 let mut min_pack: Option<Align> = None;
2253 for attr in tcx.get_attrs(did).iter() {
2254 for r in attr::find_repr_attrs(&tcx.sess, attr) {
2255 flags.insert(match r {
2256 attr::ReprC => ReprFlags::IS_C,
2257 attr::ReprPacked(pack) => {
2258 let pack = Align::from_bytes(pack as u64).unwrap();
2259 min_pack = Some(if let Some(min_pack) = min_pack {
2266 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2267 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
2268 attr::ReprSimd => ReprFlags::IS_SIMD,
2269 attr::ReprInt(i) => {
2273 attr::ReprAlign(align) => {
2274 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2281 // This is here instead of layout because the choice must make it into metadata.
2282 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2283 flags.insert(ReprFlags::IS_LINEAR);
2285 ReprOptions { int: size, align: max_align, pack: min_pack, flags }
2289 pub fn simd(&self) -> bool {
2290 self.flags.contains(ReprFlags::IS_SIMD)
2293 pub fn c(&self) -> bool {
2294 self.flags.contains(ReprFlags::IS_C)
2297 pub fn packed(&self) -> bool {
2301 pub fn transparent(&self) -> bool {
2302 self.flags.contains(ReprFlags::IS_TRANSPARENT)
2305 pub fn linear(&self) -> bool {
2306 self.flags.contains(ReprFlags::IS_LINEAR)
2309 pub fn hide_niche(&self) -> bool {
2310 self.flags.contains(ReprFlags::HIDE_NICHE)
2313 /// Returns the discriminant type, given these `repr` options.
2314 /// This must only be called on enums!
2315 pub fn discr_type(&self) -> attr::IntType {
2316 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2319 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2320 /// layout" optimizations, such as representing `Foo<&T>` as a
2322 pub fn inhibit_enum_layout_opt(&self) -> bool {
2323 self.c() || self.int.is_some()
2326 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2327 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2328 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2329 if let Some(pack) = self.pack {
2330 if pack.bytes() == 1 {
2334 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2337 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2338 pub fn inhibit_union_abi_opt(&self) -> bool {
2344 /// Creates a new `AdtDef`.
2349 variants: IndexVec<VariantIdx, VariantDef>,
2352 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
2353 let mut flags = AdtFlags::NO_ADT_FLAGS;
2355 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
2356 debug!("found non-exhaustive variant list for {:?}", did);
2357 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
2360 flags |= match kind {
2361 AdtKind::Enum => AdtFlags::IS_ENUM,
2362 AdtKind::Union => AdtFlags::IS_UNION,
2363 AdtKind::Struct => AdtFlags::IS_STRUCT,
2366 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
2367 flags |= AdtFlags::HAS_CTOR;
2370 let attrs = tcx.get_attrs(did);
2371 if tcx.sess.contains_name(&attrs, sym::fundamental) {
2372 flags |= AdtFlags::IS_FUNDAMENTAL;
2374 if Some(did) == tcx.lang_items().phantom_data() {
2375 flags |= AdtFlags::IS_PHANTOM_DATA;
2377 if Some(did) == tcx.lang_items().owned_box() {
2378 flags |= AdtFlags::IS_BOX;
2380 if Some(did) == tcx.lang_items().manually_drop() {
2381 flags |= AdtFlags::IS_MANUALLY_DROP;
2384 AdtDef { did, variants, flags, repr }
2387 /// Returns `true` if this is a struct.
2389 pub fn is_struct(&self) -> bool {
2390 self.flags.contains(AdtFlags::IS_STRUCT)
2393 /// Returns `true` if this is a union.
2395 pub fn is_union(&self) -> bool {
2396 self.flags.contains(AdtFlags::IS_UNION)
2399 /// Returns `true` if this is a enum.
2401 pub fn is_enum(&self) -> bool {
2402 self.flags.contains(AdtFlags::IS_ENUM)
2405 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
2407 pub fn is_variant_list_non_exhaustive(&self) -> bool {
2408 self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
2411 /// Returns the kind of the ADT.
2413 pub fn adt_kind(&self) -> AdtKind {
2416 } else if self.is_union() {
2423 /// Returns a description of this abstract data type.
2424 pub fn descr(&self) -> &'static str {
2425 match self.adt_kind() {
2426 AdtKind::Struct => "struct",
2427 AdtKind::Union => "union",
2428 AdtKind::Enum => "enum",
2432 /// Returns a description of a variant of this abstract data type.
2434 pub fn variant_descr(&self) -> &'static str {
2435 match self.adt_kind() {
2436 AdtKind::Struct => "struct",
2437 AdtKind::Union => "union",
2438 AdtKind::Enum => "variant",
2442 /// If this function returns `true`, it implies that `is_struct` must return `true`.
2444 pub fn has_ctor(&self) -> bool {
2445 self.flags.contains(AdtFlags::HAS_CTOR)
2448 /// Returns `true` if this type is `#[fundamental]` for the purposes
2449 /// of coherence checking.
2451 pub fn is_fundamental(&self) -> bool {
2452 self.flags.contains(AdtFlags::IS_FUNDAMENTAL)
2455 /// Returns `true` if this is `PhantomData<T>`.
2457 pub fn is_phantom_data(&self) -> bool {
2458 self.flags.contains(AdtFlags::IS_PHANTOM_DATA)
2461 /// Returns `true` if this is Box<T>.
2463 pub fn is_box(&self) -> bool {
2464 self.flags.contains(AdtFlags::IS_BOX)
2467 /// Returns `true` if this is `ManuallyDrop<T>`.
2469 pub fn is_manually_drop(&self) -> bool {
2470 self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
2473 /// Returns `true` if this type has a destructor.
2474 pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
2475 self.destructor(tcx).is_some()
2478 /// Asserts this is a struct or union and returns its unique variant.
2479 pub fn non_enum_variant(&self) -> &VariantDef {
2480 assert!(self.is_struct() || self.is_union());
2481 &self.variants[VariantIdx::new(0)]
2485 pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
2486 tcx.predicates_of(self.did)
2489 /// Returns an iterator over all fields contained
2492 pub fn all_fields(&self) -> impl Iterator<Item = &FieldDef> + Clone {
2493 self.variants.iter().flat_map(|v| v.fields.iter())
2496 pub fn is_payloadfree(&self) -> bool {
2497 !self.variants.is_empty() && self.variants.iter().all(|v| v.fields.is_empty())
2500 /// Return a `VariantDef` given a variant id.
2501 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
2502 self.variants.iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
2505 /// Return a `VariantDef` given a constructor id.
2506 pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
2509 .find(|v| v.ctor_def_id == Some(cid))
2510 .expect("variant_with_ctor_id: unknown variant")
2513 /// Return the index of `VariantDef` given a variant id.
2514 pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
2517 .find(|(_, v)| v.def_id == vid)
2518 .expect("variant_index_with_id: unknown variant")
2522 /// Return the index of `VariantDef` given a constructor id.
2523 pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
2526 .find(|(_, v)| v.ctor_def_id == Some(cid))
2527 .expect("variant_index_with_ctor_id: unknown variant")
2531 pub fn variant_of_res(&self, res: Res) -> &VariantDef {
2533 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
2534 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
2535 Res::Def(DefKind::Struct, _)
2536 | Res::Def(DefKind::Union, _)
2537 | Res::Def(DefKind::TyAlias, _)
2538 | Res::Def(DefKind::AssocTy, _)
2540 | Res::SelfCtor(..) => self.non_enum_variant(),
2541 _ => bug!("unexpected res {:?} in variant_of_res", res),
2546 pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
2547 assert!(self.is_enum());
2548 let param_env = tcx.param_env(expr_did);
2549 let repr_type = self.repr.discr_type();
2550 match tcx.const_eval_poly(expr_did) {
2552 let ty = repr_type.to_ty(tcx);
2553 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
2554 trace!("discriminants: {} ({:?})", b, repr_type);
2555 Some(Discr { val: b, ty })
2557 info!("invalid enum discriminant: {:#?}", val);
2558 crate::mir::interpret::struct_error(
2559 tcx.at(tcx.def_span(expr_did)),
2560 "constant evaluation of enum discriminant resulted in non-integer",
2567 let msg = match err {
2568 ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => {
2569 "enum discriminant evaluation failed"
2571 ErrorHandled::TooGeneric => "enum discriminant depends on generics",
2573 tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg);
2580 pub fn discriminants(
2583 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
2584 assert!(self.is_enum());
2585 let repr_type = self.repr.discr_type();
2586 let initial = repr_type.initial_discriminant(tcx);
2587 let mut prev_discr = None::<Discr<'tcx>>;
2588 self.variants.iter_enumerated().map(move |(i, v)| {
2589 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
2590 if let VariantDiscr::Explicit(expr_did) = v.discr {
2591 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
2595 prev_discr = Some(discr);
2602 pub fn variant_range(&self) -> Range<VariantIdx> {
2603 VariantIdx::new(0)..VariantIdx::new(self.variants.len())
2606 /// Computes the discriminant value used by a specific variant.
2607 /// Unlike `discriminants`, this is (amortized) constant-time,
2608 /// only doing at most one query for evaluating an explicit
2609 /// discriminant (the last one before the requested variant),
2610 /// assuming there are no constant-evaluation errors there.
2612 pub fn discriminant_for_variant(
2615 variant_index: VariantIdx,
2617 assert!(self.is_enum());
2618 let (val, offset) = self.discriminant_def_for_variant(variant_index);
2619 let explicit_value = val
2620 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
2621 .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx));
2622 explicit_value.checked_add(tcx, offset as u128).0
2625 /// Yields a `DefId` for the discriminant and an offset to add to it
2626 /// Alternatively, if there is no explicit discriminant, returns the
2627 /// inferred discriminant directly.
2628 pub fn discriminant_def_for_variant(&self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
2629 assert!(!self.variants.is_empty());
2630 let mut explicit_index = variant_index.as_u32();
2633 match self.variants[VariantIdx::from_u32(explicit_index)].discr {
2634 ty::VariantDiscr::Relative(0) => {
2638 ty::VariantDiscr::Relative(distance) => {
2639 explicit_index -= distance;
2641 ty::VariantDiscr::Explicit(did) => {
2642 expr_did = Some(did);
2647 (expr_did, variant_index.as_u32() - explicit_index)
2650 pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
2651 tcx.adt_destructor(self.did)
2654 /// Returns a list of types such that `Self: Sized` if and only
2655 /// if that type is `Sized`, or `TyErr` if this type is recursive.
2657 /// Oddly enough, checking that the sized-constraint is `Sized` is
2658 /// actually more expressive than checking all members:
2659 /// the `Sized` trait is inductive, so an associated type that references
2660 /// `Self` would prevent its containing ADT from being `Sized`.
2662 /// Due to normalization being eager, this applies even if
2663 /// the associated type is behind a pointer (e.g., issue #31299).
2664 pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] {
2665 tcx.adt_sized_constraint(self.did).0
2669 impl<'tcx> FieldDef {
2670 /// Returns the type of this field. The `subst` is typically obtained
2671 /// via the second field of `TyKind::AdtDef`.
2672 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2673 tcx.type_of(self.did).subst(tcx, subst)
2677 /// Represents the various closure traits in the language. This
2678 /// will determine the type of the environment (`self`, in the
2679 /// desugaring) argument that the closure expects.
2681 /// You can get the environment type of a closure using
2682 /// `tcx.closure_env_ty()`.
2683 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
2684 #[derive(HashStable)]
2685 pub enum ClosureKind {
2686 // Warning: Ordering is significant here! The ordering is chosen
2687 // because the trait Fn is a subtrait of FnMut and so in turn, and
2688 // hence we order it so that Fn < FnMut < FnOnce.
2694 impl<'tcx> ClosureKind {
2695 // This is the initial value used when doing upvar inference.
2696 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2698 pub fn trait_did(&self, tcx: TyCtxt<'tcx>) -> DefId {
2700 ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem, None),
2701 ClosureKind::FnMut => tcx.require_lang_item(FnMutTraitLangItem, None),
2702 ClosureKind::FnOnce => tcx.require_lang_item(FnOnceTraitLangItem, None),
2706 /// Returns `true` if this a type that impls this closure kind
2707 /// must also implement `other`.
2708 pub fn extends(self, other: ty::ClosureKind) -> bool {
2709 match (self, other) {
2710 (ClosureKind::Fn, ClosureKind::Fn) => true,
2711 (ClosureKind::Fn, ClosureKind::FnMut) => true,
2712 (ClosureKind::Fn, ClosureKind::FnOnce) => true,
2713 (ClosureKind::FnMut, ClosureKind::FnMut) => true,
2714 (ClosureKind::FnMut, ClosureKind::FnOnce) => true,
2715 (ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
2720 /// Returns the representative scalar type for this closure kind.
2721 /// See `TyS::to_opt_closure_kind` for more details.
2722 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2724 ty::ClosureKind::Fn => tcx.types.i8,
2725 ty::ClosureKind::FnMut => tcx.types.i16,
2726 ty::ClosureKind::FnOnce => tcx.types.i32,
2732 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2734 hir::Mutability::Mut => MutBorrow,
2735 hir::Mutability::Not => ImmBorrow,
2739 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2740 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2741 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2743 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2745 MutBorrow => hir::Mutability::Mut,
2746 ImmBorrow => hir::Mutability::Not,
2748 // We have no type corresponding to a unique imm borrow, so
2749 // use `&mut`. It gives all the capabilities of an `&uniq`
2750 // and hence is a safe "over approximation".
2751 UniqueImmBorrow => hir::Mutability::Mut,
2755 pub fn to_user_str(&self) -> &'static str {
2757 MutBorrow => "mutable",
2758 ImmBorrow => "immutable",
2759 UniqueImmBorrow => "uniquely immutable",
2764 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
2766 #[derive(Debug, PartialEq, Eq)]
2767 pub enum ImplOverlapKind {
2768 /// These impls are always allowed to overlap.
2770 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
2773 /// These impls are allowed to overlap, but that raises
2774 /// an issue #33140 future-compatibility warning.
2776 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2777 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2779 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2780 /// that difference, making what reduces to the following set of impls:
2784 /// impl Trait for dyn Send + Sync {}
2785 /// impl Trait for dyn Sync + Send {}
2788 /// Obviously, once we made these types be identical, that code causes a coherence
2789 /// error and a fairly big headache for us. However, luckily for us, the trait
2790 /// `Trait` used in this case is basically a marker trait, and therefore having
2791 /// overlapping impls for it is sound.
2793 /// To handle this, we basically regard the trait as a marker trait, with an additional
2794 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2795 /// it has the following restrictions:
2797 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2799 /// 2. The trait-ref of both impls must be equal.
2800 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2802 /// 4. Neither of the impls can have any where-clauses.
2804 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2808 impl<'tcx> TyCtxt<'tcx> {
2809 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
2810 self.typeck(self.hir().body_owner_def_id(body))
2813 /// Returns an iterator of the `DefId`s for all body-owners in this
2814 /// crate. If you would prefer to iterate over the bodies
2815 /// themselves, you can do `self.hir().krate().body_ids.iter()`.
2816 pub fn body_owners(self) -> impl Iterator<Item = LocalDefId> + Captures<'tcx> + 'tcx {
2821 .map(move |&body_id| self.hir().body_owner_def_id(body_id))
2824 pub fn par_body_owners<F: Fn(LocalDefId) + sync::Sync + sync::Send>(self, f: F) {
2825 par_iter(&self.hir().krate().body_ids)
2826 .for_each(|&body_id| f(self.hir().body_owner_def_id(body_id)));
2829 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
2830 self.associated_items(id)
2831 .in_definition_order()
2832 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
2835 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
2838 .and_then(|def_id| self.hir().get(self.hir().local_def_id_to_hir_id(def_id)).ident())
2841 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2842 let is_associated_item = if let Some(def_id) = def_id.as_local() {
2843 match self.hir().get(self.hir().local_def_id_to_hir_id(def_id)) {
2844 Node::TraitItem(_) | Node::ImplItem(_) => true,
2848 match self.def_kind(def_id) {
2849 DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy => true,
2854 is_associated_item.then(|| self.associated_item(def_id))
2857 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
2858 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
2861 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2862 variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id))
2865 /// Returns `true` if the impls are the same polarity and the trait either
2866 /// has no items or is annotated `#[marker]` and prevents item overrides.
2867 pub fn impls_are_allowed_to_overlap(
2871 ) -> Option<ImplOverlapKind> {
2872 // If either trait impl references an error, they're allowed to overlap,
2873 // as one of them essentially doesn't exist.
2874 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2875 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2877 return Some(ImplOverlapKind::Permitted { marker: false });
2880 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2881 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2882 // `#[rustc_reservation_impl]` impls don't overlap with anything
2884 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2887 return Some(ImplOverlapKind::Permitted { marker: false });
2889 (ImplPolarity::Positive, ImplPolarity::Negative)
2890 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2891 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2893 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2898 (ImplPolarity::Positive, ImplPolarity::Positive)
2899 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2902 let is_marker_overlap = {
2903 let is_marker_impl = |def_id: DefId| -> bool {
2904 let trait_ref = self.impl_trait_ref(def_id);
2905 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2907 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2910 if is_marker_overlap {
2912 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2915 Some(ImplOverlapKind::Permitted { marker: true })
2917 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2918 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2919 if self_ty1 == self_ty2 {
2921 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2924 return Some(ImplOverlapKind::Issue33140);
2927 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2928 def_id1, def_id2, self_ty1, self_ty2
2934 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2939 /// Returns `ty::VariantDef` if `res` refers to a struct,
2940 /// or variant or their constructors, panics otherwise.
2941 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2943 Res::Def(DefKind::Variant, did) => {
2944 let enum_did = self.parent(did).unwrap();
2945 self.adt_def(enum_did).variant_with_id(did)
2947 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2948 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2949 let variant_did = self.parent(variant_ctor_did).unwrap();
2950 let enum_did = self.parent(variant_did).unwrap();
2951 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2953 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2954 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2955 self.adt_def(struct_did).non_enum_variant()
2957 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2961 pub fn item_name(self, id: DefId) -> Symbol {
2962 if id.index == CRATE_DEF_INDEX {
2963 self.original_crate_name(id.krate)
2965 let def_key = self.def_key(id);
2966 match def_key.disambiguated_data.data {
2967 // The name of a constructor is that of its parent.
2968 rustc_hir::definitions::DefPathData::Ctor => {
2969 self.item_name(DefId { krate: id.krate, index: def_key.parent.unwrap() })
2971 _ => def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
2972 bug!("item_name: no name for {:?}", self.def_path(id));
2978 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2979 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2981 ty::InstanceDef::Item(def) => {
2982 if let Some((did, param_did)) = def.as_const_arg() {
2983 self.optimized_mir_of_const_arg((did, param_did))
2985 self.optimized_mir(def.did)
2988 ty::InstanceDef::VtableShim(..)
2989 | ty::InstanceDef::ReifyShim(..)
2990 | ty::InstanceDef::Intrinsic(..)
2991 | ty::InstanceDef::FnPtrShim(..)
2992 | ty::InstanceDef::Virtual(..)
2993 | ty::InstanceDef::ClosureOnceShim { .. }
2994 | ty::InstanceDef::DropGlue(..)
2995 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2999 /// Gets the attributes of a definition.
3000 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
3001 if let Some(did) = did.as_local() {
3002 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
3004 self.item_attrs(did)
3008 /// Determines whether an item is annotated with an attribute.
3009 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
3010 self.sess.contains_name(&self.get_attrs(did), attr)
3013 /// Returns `true` if this is an `auto trait`.
3014 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
3015 self.trait_def(trait_def_id).has_auto_impl
3018 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
3019 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
3022 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
3023 /// If it implements no trait, returns `None`.
3024 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
3025 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
3028 /// If the given defid describes a method belonging to an impl, returns the
3029 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
3030 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
3031 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
3032 TraitContainer(_) => None,
3033 ImplContainer(def_id) => Some(def_id),
3037 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
3038 /// with the name of the crate containing the impl.
3039 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
3040 if let Some(impl_did) = impl_did.as_local() {
3041 let hir_id = self.hir().local_def_id_to_hir_id(impl_did);
3042 Ok(self.hir().span(hir_id))
3044 Err(self.crate_name(impl_did.krate))
3048 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
3049 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
3050 /// definition's parent/scope to perform comparison.
3051 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
3052 // We could use `Ident::eq` here, but we deliberately don't. The name
3053 // comparison fails frequently, and we want to avoid the expensive
3054 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
3055 use_name.name == def_name.name
3059 .hygienic_eq(def_name.span.ctxt(), self.expansion_that_defined(def_parent_def_id))
3062 fn expansion_that_defined(self, scope: DefId) -> ExpnId {
3063 match scope.as_local() {
3064 Some(scope) => self.hir().definitions().expansion_that_defined(scope),
3065 None => ExpnId::root(),
3069 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
3070 ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope));
3074 pub fn adjust_ident_and_get_scope(
3079 ) -> (Ident, DefId) {
3081 match ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope))
3083 Some(actual_expansion) => {
3084 self.hir().definitions().parent_module_of_macro_def(actual_expansion)
3086 None => self.parent_module(block).to_def_id(),
3091 pub fn is_object_safe(self, key: DefId) -> bool {
3092 self.object_safety_violations(key).is_empty()
3096 #[derive(Clone, HashStable)]
3097 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
3099 /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition.
3100 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
3101 if let Some(def_id) = def_id.as_local() {
3102 if let Node::Item(item) = tcx.hir().get(tcx.hir().local_def_id_to_hir_id(def_id)) {
3103 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
3104 return opaque_ty.impl_trait_fn;
3111 pub fn provide(providers: &mut ty::query::Providers) {
3112 context::provide(providers);
3113 erase_regions::provide(providers);
3114 layout::provide(providers);
3115 util::provide(providers);
3116 super::util::bug::provide(providers);
3117 *providers = ty::query::Providers {
3118 trait_impls_of: trait_def::trait_impls_of_provider,
3119 all_local_trait_impls: trait_def::all_local_trait_impls,
3124 /// A map for the local crate mapping each type to a vector of its
3125 /// inherent impls. This is not meant to be used outside of coherence;
3126 /// rather, you should request the vector for a specific type via
3127 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
3128 /// (constructing this map requires touching the entire crate).
3129 #[derive(Clone, Debug, Default, HashStable)]
3130 pub struct CrateInherentImpls {
3131 pub inherent_impls: DefIdMap<Vec<DefId>>,
3134 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
3135 pub struct SymbolName<'tcx> {
3136 /// `&str` gives a consistent ordering, which ensures reproducible builds.
3137 pub name: &'tcx str,
3140 impl<'tcx> SymbolName<'tcx> {
3141 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
3143 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
3148 impl<'tcx> fmt::Display for SymbolName<'tcx> {
3149 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3150 fmt::Display::fmt(&self.name, fmt)
3154 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
3155 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3156 fmt::Display::fmt(&self.name, fmt)