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};
103 pub mod inhabitedness;
105 pub mod normalize_erasing_regions;
121 mod structural_impls;
126 pub struct ResolverOutputs {
127 pub definitions: rustc_hir::definitions::Definitions,
128 pub cstore: Box<CrateStoreDyn>,
129 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
130 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
131 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
132 pub export_map: ExportMap<LocalDefId>,
133 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
134 /// Extern prelude entries. The value is `true` if the entry was introduced
135 /// via `extern crate` item and not `--extern` option or compiler built-in.
136 pub extern_prelude: FxHashMap<Symbol, bool>,
139 #[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable, Hash)]
140 pub enum AssocItemContainer {
141 TraitContainer(DefId),
142 ImplContainer(DefId),
145 impl AssocItemContainer {
146 /// Asserts that this is the `DefId` of an associated item declared
147 /// in a trait, and returns the trait `DefId`.
148 pub fn assert_trait(&self) -> DefId {
150 TraitContainer(id) => id,
151 _ => bug!("associated item has wrong container type: {:?}", self),
155 pub fn id(&self) -> DefId {
157 TraitContainer(id) => id,
158 ImplContainer(id) => id,
163 /// The "header" of an impl is everything outside the body: a Self type, a trait
164 /// ref (in the case of a trait impl), and a set of predicates (from the
165 /// bounds / where-clauses).
166 #[derive(Clone, Debug, TypeFoldable)]
167 pub struct ImplHeader<'tcx> {
168 pub impl_def_id: DefId,
169 pub self_ty: Ty<'tcx>,
170 pub trait_ref: Option<TraitRef<'tcx>>,
171 pub predicates: Vec<Predicate<'tcx>>,
174 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)]
175 pub enum ImplPolarity {
176 /// `impl Trait for Type`
178 /// `impl !Trait for Type`
180 /// `#[rustc_reservation_impl] impl Trait for Type`
182 /// This is a "stability hack", not a real Rust feature.
183 /// See #64631 for details.
187 #[derive(Copy, Clone, Debug, PartialEq, HashStable, Eq, Hash)]
188 pub struct AssocItem {
190 #[stable_hasher(project(name))]
194 pub defaultness: hir::Defaultness,
195 pub container: AssocItemContainer,
197 /// Whether this is a method with an explicit self
198 /// as its first parameter, allowing method calls.
199 pub fn_has_self_parameter: bool,
202 #[derive(Copy, Clone, PartialEq, Debug, HashStable, Eq, Hash)]
210 pub fn namespace(&self) -> Namespace {
212 ty::AssocKind::Type => Namespace::TypeNS,
213 ty::AssocKind::Const | ty::AssocKind::Fn => Namespace::ValueNS,
217 pub fn as_def_kind(&self) -> DefKind {
219 AssocKind::Const => DefKind::AssocConst,
220 AssocKind::Fn => DefKind::AssocFn,
221 AssocKind::Type => DefKind::AssocTy,
227 pub fn signature(&self, tcx: TyCtxt<'_>) -> String {
229 ty::AssocKind::Fn => {
230 // We skip the binder here because the binder would deanonymize all
231 // late-bound regions, and we don't want method signatures to show up
232 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
233 // regions just fine, showing `fn(&MyType)`.
234 tcx.fn_sig(self.def_id).skip_binder().to_string()
236 ty::AssocKind::Type => format!("type {};", self.ident),
237 ty::AssocKind::Const => {
238 format!("const {}: {:?};", self.ident, tcx.type_of(self.def_id))
244 /// A list of `ty::AssocItem`s in definition order that allows for efficient lookup by name.
246 /// When doing lookup by name, we try to postpone hygienic comparison for as long as possible since
247 /// it is relatively expensive. Instead, items are indexed by `Symbol` and hygienic comparison is
248 /// done only on items with the same name.
249 #[derive(Debug, Clone, PartialEq, HashStable)]
250 pub struct AssociatedItems<'tcx> {
251 items: SortedIndexMultiMap<u32, Symbol, &'tcx ty::AssocItem>,
254 impl<'tcx> AssociatedItems<'tcx> {
255 /// Constructs an `AssociatedItems` map from a series of `ty::AssocItem`s in definition order.
256 pub fn new(items_in_def_order: impl IntoIterator<Item = &'tcx ty::AssocItem>) -> Self {
257 let items = items_in_def_order.into_iter().map(|item| (item.ident.name, item)).collect();
258 AssociatedItems { items }
261 /// Returns a slice of associated items in the order they were defined.
263 /// New code should avoid relying on definition order. If you need a particular associated item
264 /// for a known trait, make that trait a lang item instead of indexing this array.
265 pub fn in_definition_order(&self) -> impl '_ + Iterator<Item = &ty::AssocItem> {
266 self.items.iter().map(|(_, v)| *v)
269 /// Returns an iterator over all associated items with the given name, ignoring hygiene.
270 pub fn filter_by_name_unhygienic(
273 ) -> impl '_ + Iterator<Item = &ty::AssocItem> {
274 self.items.get_by_key(&name).copied()
277 /// Returns an iterator over all associated items with the given name.
279 /// Multiple items may have the same name if they are in different `Namespace`s. For example,
280 /// an associated type can have the same name as a method. Use one of the `find_by_name_and_*`
281 /// methods below if you know which item you are looking for.
282 pub fn filter_by_name(
286 parent_def_id: DefId,
287 ) -> impl 'a + Iterator<Item = &'a ty::AssocItem> {
288 self.filter_by_name_unhygienic(ident.name)
289 .filter(move |item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
292 /// Returns the associated item with the given name and `AssocKind`, if one exists.
293 pub fn find_by_name_and_kind(
298 parent_def_id: DefId,
299 ) -> Option<&ty::AssocItem> {
300 self.filter_by_name_unhygienic(ident.name)
301 .filter(|item| item.kind == kind)
302 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
305 /// Returns the associated item with the given name in the given `Namespace`, if one exists.
306 pub fn find_by_name_and_namespace(
311 parent_def_id: DefId,
312 ) -> Option<&ty::AssocItem> {
313 self.filter_by_name_unhygienic(ident.name)
314 .filter(|item| item.kind.namespace() == ns)
315 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
319 #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable, HashStable, Hash)]
320 pub enum Visibility {
321 /// Visible everywhere (including in other crates).
323 /// Visible only in the given crate-local module.
325 /// Not visible anywhere in the local crate. This is the visibility of private external items.
329 pub trait DefIdTree: Copy {
330 fn parent(self, id: DefId) -> Option<DefId>;
332 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
333 if descendant.krate != ancestor.krate {
337 while descendant != ancestor {
338 match self.parent(descendant) {
339 Some(parent) => descendant = parent,
340 None => return false,
347 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
348 fn parent(self, id: DefId) -> Option<DefId> {
349 self.def_key(id).parent.map(|index| DefId { index, ..id })
354 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
355 match visibility.node {
356 hir::VisibilityKind::Public => Visibility::Public,
357 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
358 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
359 // If there is no resolution, `resolve` will have already reported an error, so
360 // assume that the visibility is public to avoid reporting more privacy errors.
361 Res::Err => Visibility::Public,
362 def => Visibility::Restricted(def.def_id()),
364 hir::VisibilityKind::Inherited => {
365 Visibility::Restricted(tcx.parent_module(id).to_def_id())
370 /// Returns `true` if an item with this visibility is accessible from the given block.
371 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
372 let restriction = match self {
373 // Public items are visible everywhere.
374 Visibility::Public => return true,
375 // Private items from other crates are visible nowhere.
376 Visibility::Invisible => return false,
377 // Restricted items are visible in an arbitrary local module.
378 Visibility::Restricted(other) if other.krate != module.krate => return false,
379 Visibility::Restricted(module) => module,
382 tree.is_descendant_of(module, restriction)
385 /// Returns `true` if this visibility is at least as accessible as the given visibility
386 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
387 let vis_restriction = match vis {
388 Visibility::Public => return self == Visibility::Public,
389 Visibility::Invisible => return true,
390 Visibility::Restricted(module) => module,
393 self.is_accessible_from(vis_restriction, tree)
396 // Returns `true` if this item is visible anywhere in the local crate.
397 pub fn is_visible_locally(self) -> bool {
399 Visibility::Public => true,
400 Visibility::Restricted(def_id) => def_id.is_local(),
401 Visibility::Invisible => false,
406 #[derive(Copy, Clone, PartialEq, RustcDecodable, RustcEncodable, HashStable)]
408 Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
409 Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
410 Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
411 Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
414 /// The crate variances map is computed during typeck and contains the
415 /// variance of every item in the local crate. You should not use it
416 /// directly, because to do so will make your pass dependent on the
417 /// HIR of every item in the local crate. Instead, use
418 /// `tcx.variances_of()` to get the variance for a *particular*
420 #[derive(HashStable)]
421 pub struct CrateVariancesMap<'tcx> {
422 /// For each item with generics, maps to a vector of the variance
423 /// of its generics. If an item has no generics, it will have no
425 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
429 /// `a.xform(b)` combines the variance of a context with the
430 /// variance of a type with the following meaning. If we are in a
431 /// context with variance `a`, and we encounter a type argument in
432 /// a position with variance `b`, then `a.xform(b)` is the new
433 /// variance with which the argument appears.
439 /// Here, the "ambient" variance starts as covariant. `*mut T` is
440 /// invariant with respect to `T`, so the variance in which the
441 /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which
442 /// yields `Invariant`. Now, the type `Vec<T>` is covariant with
443 /// respect to its type argument `T`, and hence the variance of
444 /// the `i32` here is `Invariant.xform(Covariant)`, which results
445 /// (again) in `Invariant`.
449 /// fn(*const Vec<i32>, *mut Vec<i32)
451 /// The ambient variance is covariant. A `fn` type is
452 /// contravariant with respect to its parameters, so the variance
453 /// within which both pointer types appear is
454 /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const
455 /// T` is covariant with respect to `T`, so the variance within
456 /// which the first `Vec<i32>` appears is
457 /// `Contravariant.xform(Covariant)` or `Contravariant`. The same
458 /// is true for its `i32` argument. In the `*mut T` case, the
459 /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`,
460 /// and hence the outermost type is `Invariant` with respect to
461 /// `Vec<i32>` (and its `i32` argument).
463 /// Source: Figure 1 of "Taming the Wildcards:
464 /// Combining Definition- and Use-Site Variance" published in PLDI'11.
465 pub fn xform(self, v: ty::Variance) -> ty::Variance {
467 // Figure 1, column 1.
468 (ty::Covariant, ty::Covariant) => ty::Covariant,
469 (ty::Covariant, ty::Contravariant) => ty::Contravariant,
470 (ty::Covariant, ty::Invariant) => ty::Invariant,
471 (ty::Covariant, ty::Bivariant) => ty::Bivariant,
473 // Figure 1, column 2.
474 (ty::Contravariant, ty::Covariant) => ty::Contravariant,
475 (ty::Contravariant, ty::Contravariant) => ty::Covariant,
476 (ty::Contravariant, ty::Invariant) => ty::Invariant,
477 (ty::Contravariant, ty::Bivariant) => ty::Bivariant,
479 // Figure 1, column 3.
480 (ty::Invariant, _) => ty::Invariant,
482 // Figure 1, column 4.
483 (ty::Bivariant, _) => ty::Bivariant,
488 // Contains information needed to resolve types and (in the future) look up
489 // the types of AST nodes.
490 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
491 pub struct CReaderCacheKey {
497 /// Flags that we track on types. These flags are propagated upwards
498 /// through the type during type construction, so that we can quickly check
499 /// whether the type has various kinds of types in it without recursing
500 /// over the type itself.
501 pub struct TypeFlags: u32 {
502 // Does this have parameters? Used to determine whether substitution is
504 /// Does this have [Param]?
505 const HAS_TY_PARAM = 1 << 0;
506 /// Does this have [ReEarlyBound]?
507 const HAS_RE_PARAM = 1 << 1;
508 /// Does this have [ConstKind::Param]?
509 const HAS_CT_PARAM = 1 << 2;
511 const NEEDS_SUBST = TypeFlags::HAS_TY_PARAM.bits
512 | TypeFlags::HAS_RE_PARAM.bits
513 | TypeFlags::HAS_CT_PARAM.bits;
515 /// Does this have [Infer]?
516 const HAS_TY_INFER = 1 << 3;
517 /// Does this have [ReVar]?
518 const HAS_RE_INFER = 1 << 4;
519 /// Does this have [ConstKind::Infer]?
520 const HAS_CT_INFER = 1 << 5;
522 /// Does this have inference variables? Used to determine whether
523 /// inference is required.
524 const NEEDS_INFER = TypeFlags::HAS_TY_INFER.bits
525 | TypeFlags::HAS_RE_INFER.bits
526 | TypeFlags::HAS_CT_INFER.bits;
528 /// Does this have [Placeholder]?
529 const HAS_TY_PLACEHOLDER = 1 << 6;
530 /// Does this have [RePlaceholder]?
531 const HAS_RE_PLACEHOLDER = 1 << 7;
532 /// Does this have [ConstKind::Placeholder]?
533 const HAS_CT_PLACEHOLDER = 1 << 8;
535 /// `true` if there are "names" of regions and so forth
536 /// that are local to a particular fn/inferctxt
537 const HAS_FREE_LOCAL_REGIONS = 1 << 9;
539 /// `true` if there are "names" of types and regions and so forth
540 /// that are local to a particular fn
541 const HAS_FREE_LOCAL_NAMES = TypeFlags::HAS_TY_PARAM.bits
542 | TypeFlags::HAS_CT_PARAM.bits
543 | TypeFlags::HAS_TY_INFER.bits
544 | TypeFlags::HAS_CT_INFER.bits
545 | TypeFlags::HAS_TY_PLACEHOLDER.bits
546 | TypeFlags::HAS_CT_PLACEHOLDER.bits
547 | TypeFlags::HAS_FREE_LOCAL_REGIONS.bits;
549 /// Does this have [Projection]?
550 const HAS_TY_PROJECTION = 1 << 10;
551 /// Does this have [Opaque]?
552 const HAS_TY_OPAQUE = 1 << 11;
553 /// Does this have [ConstKind::Unevaluated]?
554 const HAS_CT_PROJECTION = 1 << 12;
556 /// Could this type be normalized further?
557 const HAS_PROJECTION = TypeFlags::HAS_TY_PROJECTION.bits
558 | TypeFlags::HAS_TY_OPAQUE.bits
559 | TypeFlags::HAS_CT_PROJECTION.bits;
561 /// Is an error type/const reachable?
562 const HAS_ERROR = 1 << 13;
564 /// Does this have any region that "appears free" in the type?
565 /// Basically anything but [ReLateBound] and [ReErased].
566 const HAS_FREE_REGIONS = 1 << 14;
568 /// Does this have any [ReLateBound] regions? Used to check
569 /// if a global bound is safe to evaluate.
570 const HAS_RE_LATE_BOUND = 1 << 15;
572 /// Does this have any [ReErased] regions?
573 const HAS_RE_ERASED = 1 << 16;
575 /// Does this value have parameters/placeholders/inference variables which could be
576 /// replaced later, in a way that would change the results of `impl` specialization?
577 const STILL_FURTHER_SPECIALIZABLE = 1 << 17;
579 /// Does this value contain closures, generators or functions such that it may require
580 /// polymorphization?
581 const MAY_POLYMORPHIZE = 1 << 18;
585 #[allow(rustc::usage_of_ty_tykind)]
586 pub struct TyS<'tcx> {
587 pub kind: TyKind<'tcx>,
588 pub flags: TypeFlags,
590 /// This is a kind of confusing thing: it stores the smallest
593 /// (a) the binder itself captures nothing but
594 /// (b) all the late-bound things within the type are captured
595 /// by some sub-binder.
597 /// So, for a type without any late-bound things, like `u32`, this
598 /// will be *innermost*, because that is the innermost binder that
599 /// captures nothing. But for a type `&'D u32`, where `'D` is a
600 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
601 /// -- the binder itself does not capture `D`, but `D` is captured
602 /// by an inner binder.
604 /// We call this concept an "exclusive" binder `D` because all
605 /// De Bruijn indices within the type are contained within `0..D`
607 outer_exclusive_binder: ty::DebruijnIndex,
610 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
611 #[cfg(target_arch = "x86_64")]
612 static_assert_size!(TyS<'_>, 32);
614 impl<'tcx> Ord for TyS<'tcx> {
615 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
616 self.kind.cmp(&other.kind)
620 impl<'tcx> PartialOrd for TyS<'tcx> {
621 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
622 Some(self.kind.cmp(&other.kind))
626 impl<'tcx> PartialEq for TyS<'tcx> {
628 fn eq(&self, other: &TyS<'tcx>) -> bool {
632 impl<'tcx> Eq for TyS<'tcx> {}
634 impl<'tcx> Hash for TyS<'tcx> {
635 fn hash<H: Hasher>(&self, s: &mut H) {
636 (self as *const TyS<'_>).hash(s)
640 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
641 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
645 // The other fields just provide fast access to information that is
646 // also contained in `kind`, so no need to hash them.
649 outer_exclusive_binder: _,
652 kind.hash_stable(hcx, hasher);
656 #[rustc_diagnostic_item = "Ty"]
657 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
659 impl<'tcx> rustc_serialize::UseSpecializedEncodable for Ty<'tcx> {}
660 impl<'tcx> rustc_serialize::UseSpecializedDecodable for Ty<'tcx> {}
661 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx List<Ty<'tcx>> {}
663 pub type CanonicalTy<'tcx> = Canonical<'tcx, Ty<'tcx>>;
665 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
666 pub struct UpvarPath {
667 pub hir_id: hir::HirId,
670 /// Upvars do not get their own `NodeId`. Instead, we use the pair of
671 /// the original var ID (that is, the root variable that is referenced
672 /// by the upvar) and the ID of the closure expression.
673 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
675 pub var_path: UpvarPath,
676 pub closure_expr_id: LocalDefId,
679 #[derive(Clone, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, HashStable)]
680 pub enum BorrowKind {
681 /// Data must be immutable and is aliasable.
684 /// Data must be immutable but not aliasable. This kind of borrow
685 /// cannot currently be expressed by the user and is used only in
686 /// implicit closure bindings. It is needed when the closure
687 /// is borrowing or mutating a mutable referent, e.g.:
689 /// let x: &mut isize = ...;
690 /// let y = || *x += 5;
692 /// If we were to try to translate this closure into a more explicit
693 /// form, we'd encounter an error with the code as written:
695 /// struct Env { x: & &mut isize }
696 /// let x: &mut isize = ...;
697 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
698 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
700 /// This is then illegal because you cannot mutate a `&mut` found
701 /// in an aliasable location. To solve, you'd have to translate with
702 /// an `&mut` borrow:
704 /// struct Env { x: & &mut isize }
705 /// let x: &mut isize = ...;
706 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
707 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
709 /// Now the assignment to `**env.x` is legal, but creating a
710 /// mutable pointer to `x` is not because `x` is not mutable. We
711 /// could fix this by declaring `x` as `let mut x`. This is ok in
712 /// user code, if awkward, but extra weird for closures, since the
713 /// borrow is hidden.
715 /// So we introduce a "unique imm" borrow -- the referent is
716 /// immutable, but not aliasable. This solves the problem. For
717 /// simplicity, we don't give users the way to express this
718 /// borrow, it's just used when translating closures.
721 /// Data is mutable and not aliasable.
725 /// Information describing the capture of an upvar. This is computed
726 /// during `typeck`, specifically by `regionck`.
727 #[derive(PartialEq, Clone, Debug, Copy, RustcEncodable, RustcDecodable, HashStable)]
728 pub enum UpvarCapture<'tcx> {
729 /// Upvar is captured by value. This is always true when the
730 /// closure is labeled `move`, but can also be true in other cases
731 /// depending on inference.
734 /// Upvar is captured by reference.
735 ByRef(UpvarBorrow<'tcx>),
738 #[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable, HashStable)]
739 pub struct UpvarBorrow<'tcx> {
740 /// The kind of borrow: by-ref upvars have access to shared
741 /// immutable borrows, which are not part of the normal language
743 pub kind: BorrowKind,
745 /// Region of the resulting reference.
746 pub region: ty::Region<'tcx>,
749 pub type UpvarListMap = FxHashMap<DefId, FxIndexMap<hir::HirId, UpvarId>>;
750 pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
752 #[derive(Clone, Copy, PartialEq, Eq)]
753 pub enum IntVarValue {
755 UintType(ast::UintTy),
758 #[derive(Clone, Copy, PartialEq, Eq)]
759 pub struct FloatVarValue(pub ast::FloatTy);
761 impl ty::EarlyBoundRegion {
762 pub fn to_bound_region(&self) -> ty::BoundRegion {
763 ty::BoundRegion::BrNamed(self.def_id, self.name)
766 /// Does this early bound region have a name? Early bound regions normally
767 /// always have names except when using anonymous lifetimes (`'_`).
768 pub fn has_name(&self) -> bool {
769 self.name != kw::UnderscoreLifetime
773 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
774 pub enum GenericParamDefKind {
778 object_lifetime_default: ObjectLifetimeDefault,
779 synthetic: Option<hir::SyntheticTyParamKind>,
784 impl GenericParamDefKind {
785 pub fn descr(&self) -> &'static str {
787 GenericParamDefKind::Lifetime => "lifetime",
788 GenericParamDefKind::Type { .. } => "type",
789 GenericParamDefKind::Const => "constant",
794 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
795 pub struct GenericParamDef {
800 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
801 /// on generic parameter `'a`/`T`, asserts data behind the parameter
802 /// `'a`/`T` won't be accessed during the parent type's `Drop` impl.
803 pub pure_wrt_drop: bool,
805 pub kind: GenericParamDefKind,
808 impl GenericParamDef {
809 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
810 if let GenericParamDefKind::Lifetime = self.kind {
811 ty::EarlyBoundRegion { def_id: self.def_id, index: self.index, name: self.name }
813 bug!("cannot convert a non-lifetime parameter def to an early bound region")
817 pub fn to_bound_region(&self) -> ty::BoundRegion {
818 if let GenericParamDefKind::Lifetime = self.kind {
819 self.to_early_bound_region_data().to_bound_region()
821 bug!("cannot convert a non-lifetime parameter def to an early bound region")
827 pub struct GenericParamCount {
828 pub lifetimes: usize,
833 /// Information about the formal type/lifetime parameters associated
834 /// with an item or method. Analogous to `hir::Generics`.
836 /// The ordering of parameters is the same as in `Subst` (excluding child generics):
837 /// `Self` (optionally), `Lifetime` params..., `Type` params...
838 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
839 pub struct Generics {
840 pub parent: Option<DefId>,
841 pub parent_count: usize,
842 pub params: Vec<GenericParamDef>,
844 /// Reverse map to the `index` field of each `GenericParamDef`.
845 #[stable_hasher(ignore)]
846 pub param_def_id_to_index: FxHashMap<DefId, u32>,
849 pub has_late_bound_regions: Option<Span>,
852 impl<'tcx> Generics {
853 pub fn count(&self) -> usize {
854 self.parent_count + self.params.len()
857 pub fn own_counts(&self) -> GenericParamCount {
858 // We could cache this as a property of `GenericParamCount`, but
859 // the aim is to refactor this away entirely eventually and the
860 // presence of this method will be a constant reminder.
861 let mut own_counts: GenericParamCount = Default::default();
863 for param in &self.params {
865 GenericParamDefKind::Lifetime => own_counts.lifetimes += 1,
866 GenericParamDefKind::Type { .. } => own_counts.types += 1,
867 GenericParamDefKind::Const => own_counts.consts += 1,
874 pub fn requires_monomorphization(&self, tcx: TyCtxt<'tcx>) -> bool {
875 if self.own_requires_monomorphization() {
879 if let Some(parent_def_id) = self.parent {
880 let parent = tcx.generics_of(parent_def_id);
881 parent.requires_monomorphization(tcx)
887 pub fn own_requires_monomorphization(&self) -> bool {
888 for param in &self.params {
890 GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true,
891 GenericParamDefKind::Lifetime => {}
897 /// Returns the `GenericParamDef` with the given index.
898 pub fn param_at(&'tcx self, param_index: usize, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
899 if let Some(index) = param_index.checked_sub(self.parent_count) {
902 tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?"))
903 .param_at(param_index, tcx)
907 /// Returns the `GenericParamDef` associated with this `EarlyBoundRegion`.
910 param: &EarlyBoundRegion,
912 ) -> &'tcx GenericParamDef {
913 let param = self.param_at(param.index as usize, tcx);
915 GenericParamDefKind::Lifetime => param,
916 _ => bug!("expected lifetime parameter, but found another generic parameter"),
920 /// Returns the `GenericParamDef` associated with this `ParamTy`.
921 pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
922 let param = self.param_at(param.index as usize, tcx);
924 GenericParamDefKind::Type { .. } => param,
925 _ => bug!("expected type parameter, but found another generic parameter"),
929 /// Returns the `GenericParamDef` associated with this `ParamConst`.
930 pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef {
931 let param = self.param_at(param.index as usize, tcx);
933 GenericParamDefKind::Const => param,
934 _ => bug!("expected const parameter, but found another generic parameter"),
939 /// Bounds on generics.
940 #[derive(Copy, Clone, Default, Debug, RustcEncodable, RustcDecodable, HashStable)]
941 pub struct GenericPredicates<'tcx> {
942 pub parent: Option<DefId>,
943 pub predicates: &'tcx [(Predicate<'tcx>, Span)],
946 impl<'tcx> GenericPredicates<'tcx> {
950 substs: SubstsRef<'tcx>,
951 ) -> InstantiatedPredicates<'tcx> {
952 let mut instantiated = InstantiatedPredicates::empty();
953 self.instantiate_into(tcx, &mut instantiated, substs);
957 pub fn instantiate_own(
960 substs: SubstsRef<'tcx>,
961 ) -> InstantiatedPredicates<'tcx> {
962 InstantiatedPredicates {
963 predicates: self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)).collect(),
964 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
971 instantiated: &mut InstantiatedPredicates<'tcx>,
972 substs: SubstsRef<'tcx>,
974 if let Some(def_id) = self.parent {
975 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
977 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)));
978 instantiated.spans.extend(self.predicates.iter().map(|(_, sp)| *sp));
981 pub fn instantiate_identity(&self, tcx: TyCtxt<'tcx>) -> InstantiatedPredicates<'tcx> {
982 let mut instantiated = InstantiatedPredicates::empty();
983 self.instantiate_identity_into(tcx, &mut instantiated);
987 fn instantiate_identity_into(
990 instantiated: &mut InstantiatedPredicates<'tcx>,
992 if let Some(def_id) = self.parent {
993 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
995 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p));
996 instantiated.spans.extend(self.predicates.iter().map(|(_, s)| s));
999 pub fn instantiate_supertrait(
1002 poly_trait_ref: &ty::PolyTraitRef<'tcx>,
1003 ) -> InstantiatedPredicates<'tcx> {
1004 assert_eq!(self.parent, None);
1005 InstantiatedPredicates {
1009 .map(|(pred, _)| pred.subst_supertrait(tcx, poly_trait_ref))
1011 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
1017 crate struct PredicateInner<'tcx> {
1018 kind: PredicateKind<'tcx>,
1020 /// See the comment for the corresponding field of [TyS].
1021 outer_exclusive_binder: ty::DebruijnIndex,
1024 #[cfg(target_arch = "x86_64")]
1025 static_assert_size!(PredicateInner<'_>, 48);
1027 #[derive(Clone, Copy, Lift)]
1028 pub struct Predicate<'tcx> {
1029 inner: &'tcx PredicateInner<'tcx>,
1032 impl rustc_serialize::UseSpecializedEncodable for Predicate<'_> {}
1033 impl rustc_serialize::UseSpecializedDecodable for Predicate<'_> {}
1035 impl<'tcx> PartialEq for Predicate<'tcx> {
1036 fn eq(&self, other: &Self) -> bool {
1037 // `self.kind` is always interned.
1038 ptr::eq(self.inner, other.inner)
1042 impl Hash for Predicate<'_> {
1043 fn hash<H: Hasher>(&self, s: &mut H) {
1044 (self.inner as *const PredicateInner<'_>).hash(s)
1048 impl<'tcx> Eq for Predicate<'tcx> {}
1050 impl<'tcx> Predicate<'tcx> {
1052 pub fn kind(self) -> &'tcx PredicateKind<'tcx> {
1056 /// Returns the inner `PredicateAtom`.
1058 /// The returned atom may contain unbound variables bound to binders skipped in this method.
1059 /// It is safe to reapply binders to the given atom.
1061 /// Note that this method panics in case this predicate has unbound variables.
1062 pub fn skip_binders(self) -> PredicateAtom<'tcx> {
1064 &PredicateKind::ForAll(binder) => binder.skip_binder(),
1065 &PredicateKind::Atom(atom) => {
1066 debug_assert!(!atom.has_escaping_bound_vars());
1072 /// Returns the inner `PredicateAtom`.
1074 /// Note that this method does not check if the predicate has unbound variables.
1076 /// Rebinding the returned atom can causes the previously bound variables
1077 /// to end up at the wrong binding level.
1078 pub fn skip_binders_unchecked(self) -> PredicateAtom<'tcx> {
1080 &PredicateKind::ForAll(binder) => binder.skip_binder(),
1081 &PredicateKind::Atom(atom) => atom,
1085 /// Allows using a `Binder<PredicateAtom<'tcx>>` even if the given predicate previously
1086 /// contained unbound variables by shifting these variables outwards.
1087 pub fn bound_atom(self, tcx: TyCtxt<'tcx>) -> Binder<PredicateAtom<'tcx>> {
1089 &PredicateKind::ForAll(binder) => binder,
1090 &PredicateKind::Atom(atom) => Binder::wrap_nonbinding(tcx, atom),
1095 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
1096 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1097 let PredicateInner {
1100 // The other fields just provide fast access to information that is
1101 // also contained in `kind`, so no need to hash them.
1103 outer_exclusive_binder: _,
1106 kind.hash_stable(hcx, hasher);
1110 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1111 #[derive(HashStable, TypeFoldable)]
1112 pub enum PredicateKind<'tcx> {
1114 ForAll(Binder<PredicateAtom<'tcx>>),
1115 Atom(PredicateAtom<'tcx>),
1118 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1119 #[derive(HashStable, TypeFoldable)]
1120 pub enum PredicateAtom<'tcx> {
1121 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
1122 /// the `Self` type of the trait reference and `A`, `B`, and `C`
1123 /// would be the type parameters.
1125 /// A trait predicate will have `Constness::Const` if it originates
1126 /// from a bound on a `const fn` without the `?const` opt-out (e.g.,
1127 /// `const fn foobar<Foo: Bar>() {}`).
1128 Trait(TraitPredicate<'tcx>, Constness),
1131 RegionOutlives(RegionOutlivesPredicate<'tcx>),
1134 TypeOutlives(TypeOutlivesPredicate<'tcx>),
1136 /// `where <T as TraitRef>::Name == X`, approximately.
1137 /// See the `ProjectionPredicate` struct for details.
1138 Projection(ProjectionPredicate<'tcx>),
1140 /// No syntax: `T` well-formed.
1141 WellFormed(GenericArg<'tcx>),
1143 /// Trait must be object-safe.
1146 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
1147 /// for some substitutions `...` and `T` being a closure type.
1148 /// Satisfied (or refuted) once we know the closure's kind.
1149 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
1152 Subtype(SubtypePredicate<'tcx>),
1154 /// Constant initializer must evaluate successfully.
1155 ConstEvaluatable(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>),
1157 /// Constants must be equal. The first component is the const that is expected.
1158 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
1161 impl<'tcx> PredicateAtom<'tcx> {
1162 /// Wraps `self` with the given qualifier if this predicate has any unbound variables.
1163 pub fn potentially_quantified(
1166 qualifier: impl FnOnce(Binder<PredicateAtom<'tcx>>) -> PredicateKind<'tcx>,
1167 ) -> Predicate<'tcx> {
1168 if self.has_escaping_bound_vars() {
1169 qualifier(Binder::bind(self))
1171 PredicateKind::Atom(self)
1177 /// The crate outlives map is computed during typeck and contains the
1178 /// outlives of every item in the local crate. You should not use it
1179 /// directly, because to do so will make your pass dependent on the
1180 /// HIR of every item in the local crate. Instead, use
1181 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
1183 #[derive(HashStable)]
1184 pub struct CratePredicatesMap<'tcx> {
1185 /// For each struct with outlive bounds, maps to a vector of the
1186 /// predicate of its outlive bounds. If an item has no outlives
1187 /// bounds, it will have no entry.
1188 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
1191 impl<'tcx> Predicate<'tcx> {
1192 /// Performs a substitution suitable for going from a
1193 /// poly-trait-ref to supertraits that must hold if that
1194 /// poly-trait-ref holds. This is slightly different from a normal
1195 /// substitution in terms of what happens with bound regions. See
1196 /// lengthy comment below for details.
1197 pub fn subst_supertrait(
1200 trait_ref: &ty::PolyTraitRef<'tcx>,
1201 ) -> Predicate<'tcx> {
1202 // The interaction between HRTB and supertraits is not entirely
1203 // obvious. Let me walk you (and myself) through an example.
1205 // Let's start with an easy case. Consider two traits:
1207 // trait Foo<'a>: Bar<'a,'a> { }
1208 // trait Bar<'b,'c> { }
1210 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
1211 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
1212 // knew that `Foo<'x>` (for any 'x) then we also know that
1213 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
1214 // normal substitution.
1216 // In terms of why this is sound, the idea is that whenever there
1217 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
1218 // holds. So if there is an impl of `T:Foo<'a>` that applies to
1219 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
1222 // Another example to be careful of is this:
1224 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
1225 // trait Bar1<'b,'c> { }
1227 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
1228 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
1229 // reason is similar to the previous example: any impl of
1230 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
1231 // basically we would want to collapse the bound lifetimes from
1232 // the input (`trait_ref`) and the supertraits.
1234 // To achieve this in practice is fairly straightforward. Let's
1235 // consider the more complicated scenario:
1237 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
1238 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
1239 // where both `'x` and `'b` would have a DB index of 1.
1240 // The substitution from the input trait-ref is therefore going to be
1241 // `'a => 'x` (where `'x` has a DB index of 1).
1242 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1243 // early-bound parameter and `'b' is a late-bound parameter with a
1245 // - If we replace `'a` with `'x` from the input, it too will have
1246 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1247 // just as we wanted.
1249 // There is only one catch. If we just apply the substitution `'a
1250 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1251 // adjust the DB index because we substituting into a binder (it
1252 // tries to be so smart...) resulting in `for<'x> for<'b>
1253 // Bar1<'x,'b>` (we have no syntax for this, so use your
1254 // imagination). Basically the 'x will have DB index of 2 and 'b
1255 // will have DB index of 1. Not quite what we want. So we apply
1256 // the substitution to the *contents* of the trait reference,
1257 // rather than the trait reference itself (put another way, the
1258 // substitution code expects equal binding levels in the values
1259 // from the substitution and the value being substituted into, and
1260 // this trick achieves that).
1261 let substs = trait_ref.skip_binder().substs;
1262 let pred = self.skip_binders();
1263 let new = pred.subst(tcx, substs);
1264 if new != pred { new.potentially_quantified(tcx, PredicateKind::ForAll) } else { self }
1268 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1269 #[derive(HashStable, TypeFoldable)]
1270 pub struct TraitPredicate<'tcx> {
1271 pub trait_ref: TraitRef<'tcx>,
1274 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1276 impl<'tcx> TraitPredicate<'tcx> {
1277 pub fn def_id(self) -> DefId {
1278 self.trait_ref.def_id
1281 pub fn self_ty(self) -> Ty<'tcx> {
1282 self.trait_ref.self_ty()
1286 impl<'tcx> PolyTraitPredicate<'tcx> {
1287 pub fn def_id(self) -> DefId {
1288 // Ok to skip binder since trait `DefId` does not care about regions.
1289 self.skip_binder().def_id()
1293 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1294 #[derive(HashStable, TypeFoldable)]
1295 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
1296 pub type PolyOutlivesPredicate<A, B> = ty::Binder<OutlivesPredicate<A, B>>;
1297 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
1298 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1299 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>;
1300 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>;
1302 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1303 #[derive(HashStable, TypeFoldable)]
1304 pub struct SubtypePredicate<'tcx> {
1305 pub a_is_expected: bool,
1309 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1311 /// This kind of predicate has no *direct* correspondent in the
1312 /// syntax, but it roughly corresponds to the syntactic forms:
1314 /// 1. `T: TraitRef<..., Item = Type>`
1315 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1317 /// In particular, form #1 is "desugared" to the combination of a
1318 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1319 /// predicates. Form #2 is a broader form in that it also permits
1320 /// equality between arbitrary types. Processing an instance of
1321 /// Form #2 eventually yields one of these `ProjectionPredicate`
1322 /// instances to normalize the LHS.
1323 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1324 #[derive(HashStable, TypeFoldable)]
1325 pub struct ProjectionPredicate<'tcx> {
1326 pub projection_ty: ProjectionTy<'tcx>,
1330 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1332 impl<'tcx> PolyProjectionPredicate<'tcx> {
1333 /// Returns the `DefId` of the associated item being projected.
1334 pub fn item_def_id(&self) -> DefId {
1335 self.skip_binder().projection_ty.item_def_id
1339 pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
1340 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1341 // `self.0.trait_ref` is permitted to have escaping regions.
1342 // This is because here `self` has a `Binder` and so does our
1343 // return value, so we are preserving the number of binding
1345 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1348 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1349 self.map_bound(|predicate| predicate.ty)
1352 /// The `DefId` of the `TraitItem` for the associated type.
1354 /// Note that this is not the `DefId` of the `TraitRef` containing this
1355 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1356 pub fn projection_def_id(&self) -> DefId {
1357 // Ok to skip binder since trait `DefId` does not care about regions.
1358 self.skip_binder().projection_ty.item_def_id
1362 pub trait ToPolyTraitRef<'tcx> {
1363 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1366 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1367 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1368 ty::Binder::dummy(*self)
1372 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1373 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1374 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1378 pub trait ToPredicate<'tcx> {
1379 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
1382 impl ToPredicate<'tcx> for PredicateKind<'tcx> {
1384 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1385 tcx.mk_predicate(self)
1389 impl ToPredicate<'tcx> for PredicateAtom<'tcx> {
1391 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1392 debug_assert!(!self.has_escaping_bound_vars(), "escaping bound vars for {:?}", self);
1393 tcx.mk_predicate(PredicateKind::Atom(self))
1397 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<TraitRef<'tcx>> {
1398 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1399 PredicateAtom::Trait(ty::TraitPredicate { trait_ref: self.value }, self.constness)
1404 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> {
1405 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1407 value: self.value.map_bound(|trait_ref| ty::TraitPredicate { trait_ref }),
1408 constness: self.constness,
1414 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitPredicate<'tcx>> {
1415 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1416 PredicateAtom::Trait(self.value.skip_binder(), self.constness)
1417 .potentially_quantified(tcx, PredicateKind::ForAll)
1421 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1422 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1423 PredicateAtom::RegionOutlives(self.skip_binder())
1424 .potentially_quantified(tcx, PredicateKind::ForAll)
1428 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1429 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1430 PredicateAtom::TypeOutlives(self.skip_binder())
1431 .potentially_quantified(tcx, PredicateKind::ForAll)
1435 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1436 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1437 PredicateAtom::Projection(self.skip_binder())
1438 .potentially_quantified(tcx, PredicateKind::ForAll)
1442 impl<'tcx> Predicate<'tcx> {
1443 pub fn to_opt_poly_trait_ref(self) -> Option<PolyTraitRef<'tcx>> {
1444 match self.skip_binders() {
1445 PredicateAtom::Trait(t, _) => Some(ty::Binder::bind(t.trait_ref)),
1446 PredicateAtom::Projection(..)
1447 | PredicateAtom::Subtype(..)
1448 | PredicateAtom::RegionOutlives(..)
1449 | PredicateAtom::WellFormed(..)
1450 | PredicateAtom::ObjectSafe(..)
1451 | PredicateAtom::ClosureKind(..)
1452 | PredicateAtom::TypeOutlives(..)
1453 | PredicateAtom::ConstEvaluatable(..)
1454 | PredicateAtom::ConstEquate(..) => None,
1458 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1459 match self.skip_binders() {
1460 PredicateAtom::TypeOutlives(data) => Some(ty::Binder::bind(data)),
1461 PredicateAtom::Trait(..)
1462 | PredicateAtom::Projection(..)
1463 | PredicateAtom::Subtype(..)
1464 | PredicateAtom::RegionOutlives(..)
1465 | PredicateAtom::WellFormed(..)
1466 | PredicateAtom::ObjectSafe(..)
1467 | PredicateAtom::ClosureKind(..)
1468 | PredicateAtom::ConstEvaluatable(..)
1469 | PredicateAtom::ConstEquate(..) => None,
1474 /// Represents the bounds declared on a particular set of type
1475 /// parameters. Should eventually be generalized into a flag list of
1476 /// where-clauses. You can obtain a `InstantiatedPredicates` list from a
1477 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1478 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1479 /// the `GenericPredicates` are expressed in terms of the bound type
1480 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1481 /// represented a set of bounds for some particular instantiation,
1482 /// meaning that the generic parameters have been substituted with
1487 /// struct Foo<T, U: Bar<T>> { ... }
1489 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1490 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1491 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1492 /// [usize:Bar<isize>]]`.
1493 #[derive(Clone, Debug, TypeFoldable)]
1494 pub struct InstantiatedPredicates<'tcx> {
1495 pub predicates: Vec<Predicate<'tcx>>,
1496 pub spans: Vec<Span>,
1499 impl<'tcx> InstantiatedPredicates<'tcx> {
1500 pub fn empty() -> InstantiatedPredicates<'tcx> {
1501 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1504 pub fn is_empty(&self) -> bool {
1505 self.predicates.is_empty()
1509 rustc_index::newtype_index! {
1510 /// "Universes" are used during type- and trait-checking in the
1511 /// presence of `for<..>` binders to control what sets of names are
1512 /// visible. Universes are arranged into a tree: the root universe
1513 /// contains names that are always visible. Each child then adds a new
1514 /// set of names that are visible, in addition to those of its parent.
1515 /// We say that the child universe "extends" the parent universe with
1518 /// To make this more concrete, consider this program:
1522 /// fn bar<T>(x: T) {
1523 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1527 /// The struct name `Foo` is in the root universe U0. But the type
1528 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1529 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1530 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1531 /// region `'a` is in a universe U2 that extends U1, because we can
1532 /// name it inside the fn type but not outside.
1534 /// Universes are used to do type- and trait-checking around these
1535 /// "forall" binders (also called **universal quantification**). The
1536 /// idea is that when, in the body of `bar`, we refer to `T` as a
1537 /// type, we aren't referring to any type in particular, but rather a
1538 /// kind of "fresh" type that is distinct from all other types we have
1539 /// actually declared. This is called a **placeholder** type, and we
1540 /// use universes to talk about this. In other words, a type name in
1541 /// universe 0 always corresponds to some "ground" type that the user
1542 /// declared, but a type name in a non-zero universe is a placeholder
1543 /// type -- an idealized representative of "types in general" that we
1544 /// use for checking generic functions.
1545 pub struct UniverseIndex {
1547 DEBUG_FORMAT = "U{}",
1551 impl UniverseIndex {
1552 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1554 /// Returns the "next" universe index in order -- this new index
1555 /// is considered to extend all previous universes. This
1556 /// corresponds to entering a `forall` quantifier. So, for
1557 /// example, suppose we have this type in universe `U`:
1560 /// for<'a> fn(&'a u32)
1563 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1564 /// new universe that extends `U` -- in this new universe, we can
1565 /// name the region `'a`, but that region was not nameable from
1566 /// `U` because it was not in scope there.
1567 pub fn next_universe(self) -> UniverseIndex {
1568 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1571 /// Returns `true` if `self` can name a name from `other` -- in other words,
1572 /// if the set of names in `self` is a superset of those in
1573 /// `other` (`self >= other`).
1574 pub fn can_name(self, other: UniverseIndex) -> bool {
1575 self.private >= other.private
1578 /// Returns `true` if `self` cannot name some names from `other` -- in other
1579 /// words, if the set of names in `self` is a strict subset of
1580 /// those in `other` (`self < other`).
1581 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1582 self.private < other.private
1586 /// The "placeholder index" fully defines a placeholder region.
1587 /// Placeholder regions are identified by both a **universe** as well
1588 /// as a "bound-region" within that universe. The `bound_region` is
1589 /// basically a name -- distinct bound regions within the same
1590 /// universe are just two regions with an unknown relationship to one
1592 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1593 pub struct Placeholder<T> {
1594 pub universe: UniverseIndex,
1598 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1600 T: HashStable<StableHashingContext<'a>>,
1602 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1603 self.universe.hash_stable(hcx, hasher);
1604 self.name.hash_stable(hcx, hasher);
1608 pub type PlaceholderRegion = Placeholder<BoundRegion>;
1610 pub type PlaceholderType = Placeholder<BoundVar>;
1612 pub type PlaceholderConst = Placeholder<BoundVar>;
1614 /// A `DefId` which is potentially bundled with its corresponding generic parameter
1615 /// in case `did` is a const argument.
1617 /// This is used to prevent cycle errors during typeck
1618 /// as `type_of(const_arg)` depends on `typeck(owning_body)`
1619 /// which once again requires the type of its generic arguments.
1621 /// Luckily we only need to deal with const arguments once we
1622 /// know their corresponding parameters. We (ab)use this by
1623 /// calling `type_of(param_did)` for these arguments.
1626 /// #![feature(const_generics)]
1630 /// fn foo<const N: usize>(&self) -> usize { N }
1634 /// fn foo<const N: u8>(&self) -> usize { 42 }
1642 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, RustcEncodable, RustcDecodable)]
1643 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1644 #[derive(Hash, HashStable)]
1645 pub struct WithOptConstParam<T> {
1647 /// The `DefId` of the corresponding generic paramter in case `did` is
1648 /// a const argument.
1650 /// Note that even if `did` is a const argument, this may still be `None`.
1651 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1652 /// to potentially update `param_did` in case it `None`.
1653 pub const_param_did: Option<DefId>,
1656 impl<T> WithOptConstParam<T> {
1657 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1659 pub fn unknown(did: T) -> WithOptConstParam<T> {
1660 WithOptConstParam { did, const_param_did: None }
1664 impl WithOptConstParam<LocalDefId> {
1665 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1666 /// `None` otherwise.
1668 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1669 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1672 /// In case `self` is unknown but `self.did` is a const argument, this returns
1673 /// a `WithOptConstParam` with the correct `const_param_did`.
1675 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1676 if self.const_param_did.is_none() {
1677 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1678 return Some(WithOptConstParam { did: self.did, const_param_did });
1685 pub fn to_global(self) -> WithOptConstParam<DefId> {
1686 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1689 pub fn def_id_for_type_of(self) -> DefId {
1690 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1694 impl WithOptConstParam<DefId> {
1695 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1698 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1701 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1702 if let Some(param_did) = self.const_param_did {
1703 if let Some(did) = self.did.as_local() {
1704 return Some((did, param_did));
1711 pub fn expect_local(self) -> WithOptConstParam<LocalDefId> {
1712 self.as_local().unwrap()
1715 pub fn is_local(self) -> bool {
1719 pub fn def_id_for_type_of(self) -> DefId {
1720 self.const_param_did.unwrap_or(self.did)
1724 /// When type checking, we use the `ParamEnv` to track
1725 /// details about the set of where-clauses that are in scope at this
1726 /// particular point.
1727 #[derive(Copy, Clone)]
1728 pub struct ParamEnv<'tcx> {
1729 // We pack the caller_bounds List pointer and a Reveal enum into this usize.
1730 // Specifically, the low bit represents Reveal, with 0 meaning `UserFacing`
1731 // and 1 meaning `All`. The rest is the pointer.
1733 // This relies on the List<Predicate<'tcx>> type having at least 2-byte
1734 // alignment. Lists start with a usize and are repr(C) so this should be
1735 // fine; there is a debug_assert in the constructor as well.
1737 // Note that the choice of 0 for UserFacing is intentional -- since it is the
1738 // first variant in Reveal this means that joining the pointer is a simple `or`.
1741 /// `Obligation`s that the caller must satisfy. This is basically
1742 /// the set of bounds on the in-scope type parameters, translated
1743 /// into `Obligation`s, and elaborated and normalized.
1745 /// Note: This is packed into the `packed_data` usize above, use the
1746 /// `caller_bounds()` method to access it.
1747 caller_bounds: PhantomData<&'tcx List<Predicate<'tcx>>>,
1749 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1750 /// want `Reveal::All`.
1752 /// Note: This is packed into the caller_bounds usize above, use the reveal()
1753 /// method to access it.
1754 reveal: PhantomData<traits::Reveal>,
1756 /// If this `ParamEnv` comes from a call to `tcx.param_env(def_id)`,
1757 /// register that `def_id` (useful for transitioning to the chalk trait
1759 pub def_id: Option<DefId>,
1762 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1763 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1764 f.debug_struct("ParamEnv")
1765 .field("caller_bounds", &self.caller_bounds())
1766 .field("reveal", &self.reveal())
1767 .field("def_id", &self.def_id)
1772 impl<'tcx> Hash for ParamEnv<'tcx> {
1773 fn hash<H: Hasher>(&self, state: &mut H) {
1774 // List hashes as the raw pointer, so we can skip splitting into the
1775 // pointer and the enum.
1776 self.packed_data.hash(state);
1777 self.def_id.hash(state);
1781 impl<'tcx> PartialEq for ParamEnv<'tcx> {
1782 fn eq(&self, other: &Self) -> bool {
1783 self.caller_bounds() == other.caller_bounds()
1784 && self.reveal() == other.reveal()
1785 && self.def_id == other.def_id
1788 impl<'tcx> Eq for ParamEnv<'tcx> {}
1790 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1791 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1792 self.caller_bounds().hash_stable(hcx, hasher);
1793 self.reveal().hash_stable(hcx, hasher);
1794 self.def_id.hash_stable(hcx, hasher);
1798 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1799 fn super_fold_with<F: ty::fold::TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1801 self.caller_bounds().fold_with(folder),
1802 self.reveal().fold_with(folder),
1803 self.def_id.fold_with(folder),
1807 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1808 self.caller_bounds().visit_with(visitor)
1809 || self.reveal().visit_with(visitor)
1810 || self.def_id.visit_with(visitor)
1814 impl<'tcx> ParamEnv<'tcx> {
1815 /// Construct a trait environment suitable for contexts where
1816 /// there are no where-clauses in scope. Hidden types (like `impl
1817 /// Trait`) are left hidden, so this is suitable for ordinary
1820 pub fn empty() -> Self {
1821 Self::new(List::empty(), Reveal::UserFacing, None)
1825 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1826 // mask out bottom bit
1827 unsafe { &*((self.packed_data & (!1)) as *const _) }
1831 pub fn reveal(self) -> traits::Reveal {
1832 if self.packed_data & 1 == 0 { traits::Reveal::UserFacing } else { traits::Reveal::All }
1835 /// Construct a trait environment with no where-clauses in scope
1836 /// where the values of all `impl Trait` and other hidden types
1837 /// are revealed. This is suitable for monomorphized, post-typeck
1838 /// environments like codegen or doing optimizations.
1840 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1841 /// or invoke `param_env.with_reveal_all()`.
1843 pub fn reveal_all() -> Self {
1844 Self::new(List::empty(), Reveal::All, None)
1847 /// Construct a trait environment with the given set of predicates.
1850 caller_bounds: &'tcx List<Predicate<'tcx>>,
1852 def_id: Option<DefId>,
1854 let packed_data = caller_bounds as *const _ as usize;
1855 // Check that we can pack the reveal data into the pointer.
1856 debug_assert!(packed_data & 1 == 0);
1858 packed_data: packed_data
1860 Reveal::UserFacing => 0,
1863 caller_bounds: PhantomData,
1864 reveal: PhantomData,
1869 pub fn with_user_facing(mut self) -> Self {
1871 self.packed_data &= !1;
1875 /// Returns a new parameter environment with the same clauses, but
1876 /// which "reveals" the true results of projections in all cases
1877 /// (even for associated types that are specializable). This is
1878 /// the desired behavior during codegen and certain other special
1879 /// contexts; normally though we want to use `Reveal::UserFacing`,
1880 /// which is the default.
1881 /// All opaque types in the caller_bounds of the `ParamEnv`
1882 /// will be normalized to their underlying types.
1883 /// See PR #65989 and issue #65918 for more details
1884 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1885 if self.packed_data & 1 == 1 {
1889 ParamEnv::new(tcx.normalize_opaque_types(self.caller_bounds()), Reveal::All, self.def_id)
1892 /// Returns this same environment but with no caller bounds.
1893 pub fn without_caller_bounds(self) -> Self {
1894 Self::new(List::empty(), self.reveal(), self.def_id)
1897 /// Creates a suitable environment in which to perform trait
1898 /// queries on the given value. When type-checking, this is simply
1899 /// the pair of the environment plus value. But when reveal is set to
1900 /// All, then if `value` does not reference any type parameters, we will
1901 /// pair it with the empty environment. This improves caching and is generally
1904 /// N.B., we preserve the environment when type-checking because it
1905 /// is possible for the user to have wacky where-clauses like
1906 /// `where Box<u32>: Copy`, which are clearly never
1907 /// satisfiable. We generally want to behave as if they were true,
1908 /// although the surrounding function is never reachable.
1909 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1910 match self.reveal() {
1911 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1914 if value.is_global() {
1915 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1917 ParamEnvAnd { param_env: self, value }
1924 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1925 pub struct ConstnessAnd<T> {
1926 pub constness: Constness,
1930 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1931 // the constness of trait bounds is being propagated correctly.
1932 pub trait WithConstness: Sized {
1934 fn with_constness(self, constness: Constness) -> ConstnessAnd<Self> {
1935 ConstnessAnd { constness, value: self }
1939 fn with_const(self) -> ConstnessAnd<Self> {
1940 self.with_constness(Constness::Const)
1944 fn without_const(self) -> ConstnessAnd<Self> {
1945 self.with_constness(Constness::NotConst)
1949 impl<T> WithConstness for T {}
1951 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1952 pub struct ParamEnvAnd<'tcx, T> {
1953 pub param_env: ParamEnv<'tcx>,
1957 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1958 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1959 (self.param_env, self.value)
1963 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1965 T: HashStable<StableHashingContext<'a>>,
1967 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1968 let ParamEnvAnd { ref param_env, ref value } = *self;
1970 param_env.hash_stable(hcx, hasher);
1971 value.hash_stable(hcx, hasher);
1975 #[derive(Copy, Clone, Debug, HashStable)]
1976 pub struct Destructor {
1977 /// The `DefId` of the destructor method
1982 #[derive(HashStable)]
1983 pub struct AdtFlags: u32 {
1984 const NO_ADT_FLAGS = 0;
1985 /// Indicates whether the ADT is an enum.
1986 const IS_ENUM = 1 << 0;
1987 /// Indicates whether the ADT is a union.
1988 const IS_UNION = 1 << 1;
1989 /// Indicates whether the ADT is a struct.
1990 const IS_STRUCT = 1 << 2;
1991 /// Indicates whether the ADT is a struct and has a constructor.
1992 const HAS_CTOR = 1 << 3;
1993 /// Indicates whether the type is `PhantomData`.
1994 const IS_PHANTOM_DATA = 1 << 4;
1995 /// Indicates whether the type has a `#[fundamental]` attribute.
1996 const IS_FUNDAMENTAL = 1 << 5;
1997 /// Indicates whether the type is `Box`.
1998 const IS_BOX = 1 << 6;
1999 /// Indicates whether the type is `ManuallyDrop`.
2000 const IS_MANUALLY_DROP = 1 << 7;
2001 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
2002 /// (i.e., this flag is never set unless this ADT is an enum).
2003 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
2008 #[derive(HashStable)]
2009 pub struct VariantFlags: u32 {
2010 const NO_VARIANT_FLAGS = 0;
2011 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
2012 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
2016 /// Definition of a variant -- a struct's fields or a enum variant.
2017 #[derive(Debug, HashStable)]
2018 pub struct VariantDef {
2019 /// `DefId` that identifies the variant itself.
2020 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
2022 /// `DefId` that identifies the variant's constructor.
2023 /// If this variant is a struct variant, then this is `None`.
2024 pub ctor_def_id: Option<DefId>,
2025 /// Variant or struct name.
2026 #[stable_hasher(project(name))]
2028 /// Discriminant of this variant.
2029 pub discr: VariantDiscr,
2030 /// Fields of this variant.
2031 pub fields: Vec<FieldDef>,
2032 /// Type of constructor of variant.
2033 pub ctor_kind: CtorKind,
2034 /// Flags of the variant (e.g. is field list non-exhaustive)?
2035 flags: VariantFlags,
2036 /// Variant is obtained as part of recovering from a syntactic error.
2037 /// May be incomplete or bogus.
2038 pub recovered: bool,
2041 impl<'tcx> VariantDef {
2042 /// Creates a new `VariantDef`.
2044 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
2045 /// represents an enum variant).
2047 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
2048 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
2050 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
2051 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
2052 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
2053 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
2054 /// built-in trait), and we do not want to load attributes twice.
2056 /// If someone speeds up attribute loading to not be a performance concern, they can
2057 /// remove this hack and use the constructor `DefId` everywhere.
2060 variant_did: Option<DefId>,
2061 ctor_def_id: Option<DefId>,
2062 discr: VariantDiscr,
2063 fields: Vec<FieldDef>,
2064 ctor_kind: CtorKind,
2068 is_field_list_non_exhaustive: bool,
2071 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
2072 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
2073 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
2076 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
2077 if is_field_list_non_exhaustive {
2078 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
2082 def_id: variant_did.unwrap_or(parent_did),
2093 /// Is this field list non-exhaustive?
2095 pub fn is_field_list_non_exhaustive(&self) -> bool {
2096 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
2099 /// `repr(transparent)` structs can have a single non-ZST field, this function returns that
2101 pub fn transparent_newtype_field(&self, tcx: TyCtxt<'tcx>) -> Option<&FieldDef> {
2102 for field in &self.fields {
2103 let field_ty = field.ty(tcx, InternalSubsts::identity_for_item(tcx, self.def_id));
2104 if !field_ty.is_zst(tcx, self.def_id) {
2113 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
2114 pub enum VariantDiscr {
2115 /// Explicit value for this variant, i.e., `X = 123`.
2116 /// The `DefId` corresponds to the embedded constant.
2119 /// The previous variant's discriminant plus one.
2120 /// For efficiency reasons, the distance from the
2121 /// last `Explicit` discriminant is being stored,
2122 /// or `0` for the first variant, if it has none.
2126 #[derive(Debug, HashStable)]
2127 pub struct FieldDef {
2129 #[stable_hasher(project(name))]
2131 pub vis: Visibility,
2134 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
2136 /// These are all interned (by `alloc_adt_def`) into the global arena.
2138 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
2139 /// This is slightly wrong because `union`s are not ADTs.
2140 /// Moreover, Rust only allows recursive data types through indirection.
2142 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
2144 /// The `DefId` of the struct, enum or union item.
2146 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
2147 pub variants: IndexVec<VariantIdx, VariantDef>,
2148 /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
2150 /// Repr options provided by the user.
2151 pub repr: ReprOptions,
2154 impl PartialOrd for AdtDef {
2155 fn partial_cmp(&self, other: &AdtDef) -> Option<Ordering> {
2156 Some(self.cmp(&other))
2160 /// There should be only one AdtDef for each `did`, therefore
2161 /// it is fine to implement `Ord` only based on `did`.
2162 impl Ord for AdtDef {
2163 fn cmp(&self, other: &AdtDef) -> Ordering {
2164 self.did.cmp(&other.did)
2168 impl PartialEq for AdtDef {
2169 // `AdtDef`s are always interned, and this is part of `TyS` equality.
2171 fn eq(&self, other: &Self) -> bool {
2172 ptr::eq(self, other)
2176 impl Eq for AdtDef {}
2178 impl Hash for AdtDef {
2180 fn hash<H: Hasher>(&self, s: &mut H) {
2181 (self as *const AdtDef).hash(s)
2185 impl<'tcx> rustc_serialize::UseSpecializedEncodable for &'tcx AdtDef {
2186 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
2191 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx AdtDef {}
2193 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
2194 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
2196 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default();
2199 let hash: Fingerprint = CACHE.with(|cache| {
2200 let addr = self as *const AdtDef as usize;
2201 *cache.borrow_mut().entry(addr).or_insert_with(|| {
2202 let ty::AdtDef { did, ref variants, ref flags, ref repr } = *self;
2204 let mut hasher = StableHasher::new();
2205 did.hash_stable(hcx, &mut hasher);
2206 variants.hash_stable(hcx, &mut hasher);
2207 flags.hash_stable(hcx, &mut hasher);
2208 repr.hash_stable(hcx, &mut hasher);
2214 hash.hash_stable(hcx, hasher);
2218 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
2225 impl Into<DataTypeKind> for AdtKind {
2226 fn into(self) -> DataTypeKind {
2228 AdtKind::Struct => DataTypeKind::Struct,
2229 AdtKind::Union => DataTypeKind::Union,
2230 AdtKind::Enum => DataTypeKind::Enum,
2236 #[derive(RustcEncodable, RustcDecodable, Default, HashStable)]
2237 pub struct ReprFlags: u8 {
2238 const IS_C = 1 << 0;
2239 const IS_SIMD = 1 << 1;
2240 const IS_TRANSPARENT = 1 << 2;
2241 // Internal only for now. If true, don't reorder fields.
2242 const IS_LINEAR = 1 << 3;
2243 // If true, don't expose any niche to type's context.
2244 const HIDE_NICHE = 1 << 4;
2245 // Any of these flags being set prevent field reordering optimisation.
2246 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
2247 ReprFlags::IS_SIMD.bits |
2248 ReprFlags::IS_LINEAR.bits;
2252 /// Represents the repr options provided by the user,
2253 #[derive(Copy, Clone, Debug, Eq, PartialEq, RustcEncodable, RustcDecodable, Default, HashStable)]
2254 pub struct ReprOptions {
2255 pub int: Option<attr::IntType>,
2256 pub align: Option<Align>,
2257 pub pack: Option<Align>,
2258 pub flags: ReprFlags,
2262 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
2263 let mut flags = ReprFlags::empty();
2264 let mut size = None;
2265 let mut max_align: Option<Align> = None;
2266 let mut min_pack: Option<Align> = None;
2267 for attr in tcx.get_attrs(did).iter() {
2268 for r in attr::find_repr_attrs(&tcx.sess, attr) {
2269 flags.insert(match r {
2270 attr::ReprC => ReprFlags::IS_C,
2271 attr::ReprPacked(pack) => {
2272 let pack = Align::from_bytes(pack as u64).unwrap();
2273 min_pack = Some(if let Some(min_pack) = min_pack {
2280 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2281 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
2282 attr::ReprSimd => ReprFlags::IS_SIMD,
2283 attr::ReprInt(i) => {
2287 attr::ReprAlign(align) => {
2288 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2295 // This is here instead of layout because the choice must make it into metadata.
2296 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2297 flags.insert(ReprFlags::IS_LINEAR);
2299 ReprOptions { int: size, align: max_align, pack: min_pack, flags }
2303 pub fn simd(&self) -> bool {
2304 self.flags.contains(ReprFlags::IS_SIMD)
2307 pub fn c(&self) -> bool {
2308 self.flags.contains(ReprFlags::IS_C)
2311 pub fn packed(&self) -> bool {
2315 pub fn transparent(&self) -> bool {
2316 self.flags.contains(ReprFlags::IS_TRANSPARENT)
2319 pub fn linear(&self) -> bool {
2320 self.flags.contains(ReprFlags::IS_LINEAR)
2323 pub fn hide_niche(&self) -> bool {
2324 self.flags.contains(ReprFlags::HIDE_NICHE)
2327 /// Returns the discriminant type, given these `repr` options.
2328 /// This must only be called on enums!
2329 pub fn discr_type(&self) -> attr::IntType {
2330 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2333 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2334 /// layout" optimizations, such as representing `Foo<&T>` as a
2336 pub fn inhibit_enum_layout_opt(&self) -> bool {
2337 self.c() || self.int.is_some()
2340 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2341 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2342 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2343 if let Some(pack) = self.pack {
2344 if pack.bytes() == 1 {
2348 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2351 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2352 pub fn inhibit_union_abi_opt(&self) -> bool {
2358 /// Creates a new `AdtDef`.
2363 variants: IndexVec<VariantIdx, VariantDef>,
2366 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
2367 let mut flags = AdtFlags::NO_ADT_FLAGS;
2369 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
2370 debug!("found non-exhaustive variant list for {:?}", did);
2371 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
2374 flags |= match kind {
2375 AdtKind::Enum => AdtFlags::IS_ENUM,
2376 AdtKind::Union => AdtFlags::IS_UNION,
2377 AdtKind::Struct => AdtFlags::IS_STRUCT,
2380 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
2381 flags |= AdtFlags::HAS_CTOR;
2384 let attrs = tcx.get_attrs(did);
2385 if tcx.sess.contains_name(&attrs, sym::fundamental) {
2386 flags |= AdtFlags::IS_FUNDAMENTAL;
2388 if Some(did) == tcx.lang_items().phantom_data() {
2389 flags |= AdtFlags::IS_PHANTOM_DATA;
2391 if Some(did) == tcx.lang_items().owned_box() {
2392 flags |= AdtFlags::IS_BOX;
2394 if Some(did) == tcx.lang_items().manually_drop() {
2395 flags |= AdtFlags::IS_MANUALLY_DROP;
2398 AdtDef { did, variants, flags, repr }
2401 /// Returns `true` if this is a struct.
2403 pub fn is_struct(&self) -> bool {
2404 self.flags.contains(AdtFlags::IS_STRUCT)
2407 /// Returns `true` if this is a union.
2409 pub fn is_union(&self) -> bool {
2410 self.flags.contains(AdtFlags::IS_UNION)
2413 /// Returns `true` if this is a enum.
2415 pub fn is_enum(&self) -> bool {
2416 self.flags.contains(AdtFlags::IS_ENUM)
2419 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
2421 pub fn is_variant_list_non_exhaustive(&self) -> bool {
2422 self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
2425 /// Returns the kind of the ADT.
2427 pub fn adt_kind(&self) -> AdtKind {
2430 } else if self.is_union() {
2437 /// Returns a description of this abstract data type.
2438 pub fn descr(&self) -> &'static str {
2439 match self.adt_kind() {
2440 AdtKind::Struct => "struct",
2441 AdtKind::Union => "union",
2442 AdtKind::Enum => "enum",
2446 /// Returns a description of a variant of this abstract data type.
2448 pub fn variant_descr(&self) -> &'static str {
2449 match self.adt_kind() {
2450 AdtKind::Struct => "struct",
2451 AdtKind::Union => "union",
2452 AdtKind::Enum => "variant",
2456 /// If this function returns `true`, it implies that `is_struct` must return `true`.
2458 pub fn has_ctor(&self) -> bool {
2459 self.flags.contains(AdtFlags::HAS_CTOR)
2462 /// Returns `true` if this type is `#[fundamental]` for the purposes
2463 /// of coherence checking.
2465 pub fn is_fundamental(&self) -> bool {
2466 self.flags.contains(AdtFlags::IS_FUNDAMENTAL)
2469 /// Returns `true` if this is `PhantomData<T>`.
2471 pub fn is_phantom_data(&self) -> bool {
2472 self.flags.contains(AdtFlags::IS_PHANTOM_DATA)
2475 /// Returns `true` if this is Box<T>.
2477 pub fn is_box(&self) -> bool {
2478 self.flags.contains(AdtFlags::IS_BOX)
2481 /// Returns `true` if this is `ManuallyDrop<T>`.
2483 pub fn is_manually_drop(&self) -> bool {
2484 self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
2487 /// Returns `true` if this type has a destructor.
2488 pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
2489 self.destructor(tcx).is_some()
2492 /// Asserts this is a struct or union and returns its unique variant.
2493 pub fn non_enum_variant(&self) -> &VariantDef {
2494 assert!(self.is_struct() || self.is_union());
2495 &self.variants[VariantIdx::new(0)]
2499 pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
2500 tcx.predicates_of(self.did)
2503 /// Returns an iterator over all fields contained
2506 pub fn all_fields(&self) -> impl Iterator<Item = &FieldDef> + Clone {
2507 self.variants.iter().flat_map(|v| v.fields.iter())
2510 pub fn is_payloadfree(&self) -> bool {
2511 !self.variants.is_empty() && self.variants.iter().all(|v| v.fields.is_empty())
2514 /// Return a `VariantDef` given a variant id.
2515 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
2516 self.variants.iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
2519 /// Return a `VariantDef` given a constructor id.
2520 pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
2523 .find(|v| v.ctor_def_id == Some(cid))
2524 .expect("variant_with_ctor_id: unknown variant")
2527 /// Return the index of `VariantDef` given a variant id.
2528 pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
2531 .find(|(_, v)| v.def_id == vid)
2532 .expect("variant_index_with_id: unknown variant")
2536 /// Return the index of `VariantDef` given a constructor id.
2537 pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
2540 .find(|(_, v)| v.ctor_def_id == Some(cid))
2541 .expect("variant_index_with_ctor_id: unknown variant")
2545 pub fn variant_of_res(&self, res: Res) -> &VariantDef {
2547 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
2548 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
2549 Res::Def(DefKind::Struct, _)
2550 | Res::Def(DefKind::Union, _)
2551 | Res::Def(DefKind::TyAlias, _)
2552 | Res::Def(DefKind::AssocTy, _)
2554 | Res::SelfCtor(..) => self.non_enum_variant(),
2555 _ => bug!("unexpected res {:?} in variant_of_res", res),
2560 pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
2561 assert!(self.is_enum());
2562 let param_env = tcx.param_env(expr_did);
2563 let repr_type = self.repr.discr_type();
2564 match tcx.const_eval_poly(expr_did) {
2566 let ty = repr_type.to_ty(tcx);
2567 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
2568 trace!("discriminants: {} ({:?})", b, repr_type);
2569 Some(Discr { val: b, ty })
2571 info!("invalid enum discriminant: {:#?}", val);
2572 crate::mir::interpret::struct_error(
2573 tcx.at(tcx.def_span(expr_did)),
2574 "constant evaluation of enum discriminant resulted in non-integer",
2581 let msg = match err {
2582 ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => {
2583 "enum discriminant evaluation failed"
2585 ErrorHandled::TooGeneric => "enum discriminant depends on generics",
2587 tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg);
2594 pub fn discriminants(
2597 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
2598 assert!(self.is_enum());
2599 let repr_type = self.repr.discr_type();
2600 let initial = repr_type.initial_discriminant(tcx);
2601 let mut prev_discr = None::<Discr<'tcx>>;
2602 self.variants.iter_enumerated().map(move |(i, v)| {
2603 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
2604 if let VariantDiscr::Explicit(expr_did) = v.discr {
2605 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
2609 prev_discr = Some(discr);
2616 pub fn variant_range(&self) -> Range<VariantIdx> {
2617 VariantIdx::new(0)..VariantIdx::new(self.variants.len())
2620 /// Computes the discriminant value used by a specific variant.
2621 /// Unlike `discriminants`, this is (amortized) constant-time,
2622 /// only doing at most one query for evaluating an explicit
2623 /// discriminant (the last one before the requested variant),
2624 /// assuming there are no constant-evaluation errors there.
2626 pub fn discriminant_for_variant(
2629 variant_index: VariantIdx,
2631 assert!(self.is_enum());
2632 let (val, offset) = self.discriminant_def_for_variant(variant_index);
2633 let explicit_value = val
2634 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
2635 .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx));
2636 explicit_value.checked_add(tcx, offset as u128).0
2639 /// Yields a `DefId` for the discriminant and an offset to add to it
2640 /// Alternatively, if there is no explicit discriminant, returns the
2641 /// inferred discriminant directly.
2642 pub fn discriminant_def_for_variant(&self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
2643 assert!(!self.variants.is_empty());
2644 let mut explicit_index = variant_index.as_u32();
2647 match self.variants[VariantIdx::from_u32(explicit_index)].discr {
2648 ty::VariantDiscr::Relative(0) => {
2652 ty::VariantDiscr::Relative(distance) => {
2653 explicit_index -= distance;
2655 ty::VariantDiscr::Explicit(did) => {
2656 expr_did = Some(did);
2661 (expr_did, variant_index.as_u32() - explicit_index)
2664 pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
2665 tcx.adt_destructor(self.did)
2668 /// Returns a list of types such that `Self: Sized` if and only
2669 /// if that type is `Sized`, or `TyErr` if this type is recursive.
2671 /// Oddly enough, checking that the sized-constraint is `Sized` is
2672 /// actually more expressive than checking all members:
2673 /// the `Sized` trait is inductive, so an associated type that references
2674 /// `Self` would prevent its containing ADT from being `Sized`.
2676 /// Due to normalization being eager, this applies even if
2677 /// the associated type is behind a pointer (e.g., issue #31299).
2678 pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] {
2679 tcx.adt_sized_constraint(self.did).0
2683 impl<'tcx> FieldDef {
2684 /// Returns the type of this field. The `subst` is typically obtained
2685 /// via the second field of `TyKind::AdtDef`.
2686 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2687 tcx.type_of(self.did).subst(tcx, subst)
2691 /// Represents the various closure traits in the language. This
2692 /// will determine the type of the environment (`self`, in the
2693 /// desugaring) argument that the closure expects.
2695 /// You can get the environment type of a closure using
2696 /// `tcx.closure_env_ty()`.
2697 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
2698 #[derive(HashStable)]
2699 pub enum ClosureKind {
2700 // Warning: Ordering is significant here! The ordering is chosen
2701 // because the trait Fn is a subtrait of FnMut and so in turn, and
2702 // hence we order it so that Fn < FnMut < FnOnce.
2708 impl<'tcx> ClosureKind {
2709 // This is the initial value used when doing upvar inference.
2710 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2712 pub fn trait_did(&self, tcx: TyCtxt<'tcx>) -> DefId {
2714 ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem, None),
2715 ClosureKind::FnMut => tcx.require_lang_item(FnMutTraitLangItem, None),
2716 ClosureKind::FnOnce => tcx.require_lang_item(FnOnceTraitLangItem, None),
2720 /// Returns `true` if this a type that impls this closure kind
2721 /// must also implement `other`.
2722 pub fn extends(self, other: ty::ClosureKind) -> bool {
2723 match (self, other) {
2724 (ClosureKind::Fn, ClosureKind::Fn) => true,
2725 (ClosureKind::Fn, ClosureKind::FnMut) => true,
2726 (ClosureKind::Fn, ClosureKind::FnOnce) => true,
2727 (ClosureKind::FnMut, ClosureKind::FnMut) => true,
2728 (ClosureKind::FnMut, ClosureKind::FnOnce) => true,
2729 (ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
2734 /// Returns the representative scalar type for this closure kind.
2735 /// See `TyS::to_opt_closure_kind` for more details.
2736 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2738 ty::ClosureKind::Fn => tcx.types.i8,
2739 ty::ClosureKind::FnMut => tcx.types.i16,
2740 ty::ClosureKind::FnOnce => tcx.types.i32,
2746 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2748 hir::Mutability::Mut => MutBorrow,
2749 hir::Mutability::Not => ImmBorrow,
2753 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2754 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2755 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2757 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2759 MutBorrow => hir::Mutability::Mut,
2760 ImmBorrow => hir::Mutability::Not,
2762 // We have no type corresponding to a unique imm borrow, so
2763 // use `&mut`. It gives all the capabilities of an `&uniq`
2764 // and hence is a safe "over approximation".
2765 UniqueImmBorrow => hir::Mutability::Mut,
2769 pub fn to_user_str(&self) -> &'static str {
2771 MutBorrow => "mutable",
2772 ImmBorrow => "immutable",
2773 UniqueImmBorrow => "uniquely immutable",
2778 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
2780 #[derive(Debug, PartialEq, Eq)]
2781 pub enum ImplOverlapKind {
2782 /// These impls are always allowed to overlap.
2784 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
2787 /// These impls are allowed to overlap, but that raises
2788 /// an issue #33140 future-compatibility warning.
2790 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2791 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2793 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2794 /// that difference, making what reduces to the following set of impls:
2798 /// impl Trait for dyn Send + Sync {}
2799 /// impl Trait for dyn Sync + Send {}
2802 /// Obviously, once we made these types be identical, that code causes a coherence
2803 /// error and a fairly big headache for us. However, luckily for us, the trait
2804 /// `Trait` used in this case is basically a marker trait, and therefore having
2805 /// overlapping impls for it is sound.
2807 /// To handle this, we basically regard the trait as a marker trait, with an additional
2808 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2809 /// it has the following restrictions:
2811 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2813 /// 2. The trait-ref of both impls must be equal.
2814 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2816 /// 4. Neither of the impls can have any where-clauses.
2818 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2822 impl<'tcx> TyCtxt<'tcx> {
2823 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
2824 self.typeck(self.hir().body_owner_def_id(body))
2827 /// Returns an iterator of the `DefId`s for all body-owners in this
2828 /// crate. If you would prefer to iterate over the bodies
2829 /// themselves, you can do `self.hir().krate().body_ids.iter()`.
2830 pub fn body_owners(self) -> impl Iterator<Item = LocalDefId> + Captures<'tcx> + 'tcx {
2835 .map(move |&body_id| self.hir().body_owner_def_id(body_id))
2838 pub fn par_body_owners<F: Fn(LocalDefId) + sync::Sync + sync::Send>(self, f: F) {
2839 par_iter(&self.hir().krate().body_ids)
2840 .for_each(|&body_id| f(self.hir().body_owner_def_id(body_id)));
2843 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
2844 self.associated_items(id)
2845 .in_definition_order()
2846 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
2849 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
2852 .and_then(|def_id| self.hir().get(self.hir().as_local_hir_id(def_id)).ident())
2855 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2856 let is_associated_item = if let Some(def_id) = def_id.as_local() {
2857 match self.hir().get(self.hir().as_local_hir_id(def_id)) {
2858 Node::TraitItem(_) | Node::ImplItem(_) => true,
2862 match self.def_kind(def_id) {
2863 DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy => true,
2868 is_associated_item.then(|| self.associated_item(def_id))
2871 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
2872 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
2875 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2876 variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id))
2879 /// Returns `true` if the impls are the same polarity and the trait either
2880 /// has no items or is annotated `#[marker]` and prevents item overrides.
2881 pub fn impls_are_allowed_to_overlap(
2885 ) -> Option<ImplOverlapKind> {
2886 // If either trait impl references an error, they're allowed to overlap,
2887 // as one of them essentially doesn't exist.
2888 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2889 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2891 return Some(ImplOverlapKind::Permitted { marker: false });
2894 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2895 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2896 // `#[rustc_reservation_impl]` impls don't overlap with anything
2898 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2901 return Some(ImplOverlapKind::Permitted { marker: false });
2903 (ImplPolarity::Positive, ImplPolarity::Negative)
2904 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2905 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2907 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2912 (ImplPolarity::Positive, ImplPolarity::Positive)
2913 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2916 let is_marker_overlap = {
2917 let is_marker_impl = |def_id: DefId| -> bool {
2918 let trait_ref = self.impl_trait_ref(def_id);
2919 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2921 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2924 if is_marker_overlap {
2926 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2929 Some(ImplOverlapKind::Permitted { marker: true })
2931 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2932 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2933 if self_ty1 == self_ty2 {
2935 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2938 return Some(ImplOverlapKind::Issue33140);
2941 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2942 def_id1, def_id2, self_ty1, self_ty2
2948 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2953 /// Returns `ty::VariantDef` if `res` refers to a struct,
2954 /// or variant or their constructors, panics otherwise.
2955 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2957 Res::Def(DefKind::Variant, did) => {
2958 let enum_did = self.parent(did).unwrap();
2959 self.adt_def(enum_did).variant_with_id(did)
2961 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2962 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2963 let variant_did = self.parent(variant_ctor_did).unwrap();
2964 let enum_did = self.parent(variant_did).unwrap();
2965 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2967 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2968 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2969 self.adt_def(struct_did).non_enum_variant()
2971 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2975 pub fn item_name(self, id: DefId) -> Symbol {
2976 if id.index == CRATE_DEF_INDEX {
2977 self.original_crate_name(id.krate)
2979 let def_key = self.def_key(id);
2980 match def_key.disambiguated_data.data {
2981 // The name of a constructor is that of its parent.
2982 rustc_hir::definitions::DefPathData::Ctor => {
2983 self.item_name(DefId { krate: id.krate, index: def_key.parent.unwrap() })
2985 _ => def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
2986 bug!("item_name: no name for {:?}", self.def_path(id));
2992 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2993 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2995 ty::InstanceDef::Item(def) => {
2996 if let Some((did, param_did)) = def.as_const_arg() {
2997 self.optimized_mir_of_const_arg((did, param_did))
2999 self.optimized_mir(def.did)
3002 ty::InstanceDef::VtableShim(..)
3003 | ty::InstanceDef::ReifyShim(..)
3004 | ty::InstanceDef::Intrinsic(..)
3005 | ty::InstanceDef::FnPtrShim(..)
3006 | ty::InstanceDef::Virtual(..)
3007 | ty::InstanceDef::ClosureOnceShim { .. }
3008 | ty::InstanceDef::DropGlue(..)
3009 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
3013 /// Gets the attributes of a definition.
3014 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
3015 if let Some(did) = did.as_local() {
3016 self.hir().attrs(self.hir().as_local_hir_id(did))
3018 self.item_attrs(did)
3022 /// Determines whether an item is annotated with an attribute.
3023 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
3024 self.sess.contains_name(&self.get_attrs(did), attr)
3027 /// Returns `true` if this is an `auto trait`.
3028 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
3029 self.trait_def(trait_def_id).has_auto_impl
3032 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
3033 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
3036 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
3037 /// If it implements no trait, returns `None`.
3038 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
3039 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
3042 /// If the given defid describes a method belonging to an impl, returns the
3043 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
3044 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
3045 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
3046 TraitContainer(_) => None,
3047 ImplContainer(def_id) => Some(def_id),
3051 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
3052 /// with the name of the crate containing the impl.
3053 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
3054 if let Some(impl_did) = impl_did.as_local() {
3055 let hir_id = self.hir().as_local_hir_id(impl_did);
3056 Ok(self.hir().span(hir_id))
3058 Err(self.crate_name(impl_did.krate))
3062 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
3063 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
3064 /// definition's parent/scope to perform comparison.
3065 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
3066 // We could use `Ident::eq` here, but we deliberately don't. The name
3067 // comparison fails frequently, and we want to avoid the expensive
3068 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
3069 use_name.name == def_name.name
3073 .hygienic_eq(def_name.span.ctxt(), self.expansion_that_defined(def_parent_def_id))
3076 fn expansion_that_defined(self, scope: DefId) -> ExpnId {
3077 match scope.as_local() {
3078 Some(scope) => self.hir().definitions().expansion_that_defined(scope),
3079 None => ExpnId::root(),
3083 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
3084 ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope));
3088 pub fn adjust_ident_and_get_scope(
3093 ) -> (Ident, DefId) {
3095 match ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope))
3097 Some(actual_expansion) => {
3098 self.hir().definitions().parent_module_of_macro_def(actual_expansion)
3100 None => self.parent_module(block).to_def_id(),
3105 pub fn is_object_safe(self, key: DefId) -> bool {
3106 self.object_safety_violations(key).is_empty()
3110 #[derive(Clone, HashStable)]
3111 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
3113 /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition.
3114 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
3115 if let Some(def_id) = def_id.as_local() {
3116 if let Node::Item(item) = tcx.hir().get(tcx.hir().as_local_hir_id(def_id)) {
3117 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
3118 return opaque_ty.impl_trait_fn;
3125 pub fn provide(providers: &mut ty::query::Providers) {
3126 context::provide(providers);
3127 erase_regions::provide(providers);
3128 layout::provide(providers);
3129 util::provide(providers);
3130 super::util::bug::provide(providers);
3131 *providers = ty::query::Providers {
3132 trait_impls_of: trait_def::trait_impls_of_provider,
3133 all_local_trait_impls: trait_def::all_local_trait_impls,
3138 /// A map for the local crate mapping each type to a vector of its
3139 /// inherent impls. This is not meant to be used outside of coherence;
3140 /// rather, you should request the vector for a specific type via
3141 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
3142 /// (constructing this map requires touching the entire crate).
3143 #[derive(Clone, Debug, Default, HashStable)]
3144 pub struct CrateInherentImpls {
3145 pub inherent_impls: DefIdMap<Vec<DefId>>,
3148 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
3149 pub struct SymbolName<'tcx> {
3150 /// `&str` gives a consistent ordering, which ensures reproducible builds.
3151 pub name: &'tcx str,
3154 impl<'tcx> SymbolName<'tcx> {
3155 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
3157 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
3162 impl<'tcx> fmt::Display for SymbolName<'tcx> {
3163 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3164 fmt::Display::fmt(&self.name, fmt)
3168 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
3169 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3170 fmt::Display::fmt(&self.name, fmt)
3174 impl<'tcx> rustc_serialize::UseSpecializedEncodable for SymbolName<'tcx> {
3175 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
3176 s.emit_str(self.name)
3180 // The decoding takes place in `decode_symbol_name()`.
3181 impl<'tcx> rustc_serialize::UseSpecializedDecodable for SymbolName<'tcx> {}