1 // ignore-tidy-filelength
2 pub use self::fold::{TypeFoldable, 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)]
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)]
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)]
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)]
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;
581 #[allow(rustc::usage_of_ty_tykind)]
582 pub struct TyS<'tcx> {
583 pub kind: TyKind<'tcx>,
584 pub flags: TypeFlags,
586 /// This is a kind of confusing thing: it stores the smallest
589 /// (a) the binder itself captures nothing but
590 /// (b) all the late-bound things within the type are captured
591 /// by some sub-binder.
593 /// So, for a type without any late-bound things, like `u32`, this
594 /// will be *innermost*, because that is the innermost binder that
595 /// captures nothing. But for a type `&'D u32`, where `'D` is a
596 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
597 /// -- the binder itself does not capture `D`, but `D` is captured
598 /// by an inner binder.
600 /// We call this concept an "exclusive" binder `D` because all
601 /// De Bruijn indices within the type are contained within `0..D`
603 outer_exclusive_binder: ty::DebruijnIndex,
606 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
607 #[cfg(target_arch = "x86_64")]
608 static_assert_size!(TyS<'_>, 32);
610 impl<'tcx> Ord for TyS<'tcx> {
611 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
612 self.kind.cmp(&other.kind)
616 impl<'tcx> PartialOrd for TyS<'tcx> {
617 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
618 Some(self.kind.cmp(&other.kind))
622 impl<'tcx> PartialEq for TyS<'tcx> {
624 fn eq(&self, other: &TyS<'tcx>) -> bool {
628 impl<'tcx> Eq for TyS<'tcx> {}
630 impl<'tcx> Hash for TyS<'tcx> {
631 fn hash<H: Hasher>(&self, s: &mut H) {
632 (self as *const TyS<'_>).hash(s)
636 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
637 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
641 // The other fields just provide fast access to information that is
642 // also contained in `kind`, so no need to hash them.
645 outer_exclusive_binder: _,
648 kind.hash_stable(hcx, hasher);
652 #[rustc_diagnostic_item = "Ty"]
653 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
655 impl<'tcx> rustc_serialize::UseSpecializedEncodable for Ty<'tcx> {}
656 impl<'tcx> rustc_serialize::UseSpecializedDecodable for Ty<'tcx> {}
657 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx List<Ty<'tcx>> {}
659 pub type CanonicalTy<'tcx> = Canonical<'tcx, Ty<'tcx>>;
661 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
662 pub struct UpvarPath {
663 pub hir_id: hir::HirId,
666 /// Upvars do not get their own `NodeId`. Instead, we use the pair of
667 /// the original var ID (that is, the root variable that is referenced
668 /// by the upvar) and the ID of the closure expression.
669 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
671 pub var_path: UpvarPath,
672 pub closure_expr_id: LocalDefId,
675 #[derive(Clone, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, HashStable)]
676 pub enum BorrowKind {
677 /// Data must be immutable and is aliasable.
680 /// Data must be immutable but not aliasable. This kind of borrow
681 /// cannot currently be expressed by the user and is used only in
682 /// implicit closure bindings. It is needed when the closure
683 /// is borrowing or mutating a mutable referent, e.g.:
685 /// let x: &mut isize = ...;
686 /// let y = || *x += 5;
688 /// If we were to try to translate this closure into a more explicit
689 /// form, we'd encounter an error with the code as written:
691 /// struct Env { x: & &mut isize }
692 /// let x: &mut isize = ...;
693 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
694 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
696 /// This is then illegal because you cannot mutate a `&mut` found
697 /// in an aliasable location. To solve, you'd have to translate with
698 /// an `&mut` borrow:
700 /// struct Env { x: & &mut isize }
701 /// let x: &mut isize = ...;
702 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
703 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
705 /// Now the assignment to `**env.x` is legal, but creating a
706 /// mutable pointer to `x` is not because `x` is not mutable. We
707 /// could fix this by declaring `x` as `let mut x`. This is ok in
708 /// user code, if awkward, but extra weird for closures, since the
709 /// borrow is hidden.
711 /// So we introduce a "unique imm" borrow -- the referent is
712 /// immutable, but not aliasable. This solves the problem. For
713 /// simplicity, we don't give users the way to express this
714 /// borrow, it's just used when translating closures.
717 /// Data is mutable and not aliasable.
721 /// Information describing the capture of an upvar. This is computed
722 /// during `typeck`, specifically by `regionck`.
723 #[derive(PartialEq, Clone, Debug, Copy, RustcEncodable, RustcDecodable, HashStable)]
724 pub enum UpvarCapture<'tcx> {
725 /// Upvar is captured by value. This is always true when the
726 /// closure is labeled `move`, but can also be true in other cases
727 /// depending on inference.
730 /// Upvar is captured by reference.
731 ByRef(UpvarBorrow<'tcx>),
734 #[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable, HashStable)]
735 pub struct UpvarBorrow<'tcx> {
736 /// The kind of borrow: by-ref upvars have access to shared
737 /// immutable borrows, which are not part of the normal language
739 pub kind: BorrowKind,
741 /// Region of the resulting reference.
742 pub region: ty::Region<'tcx>,
745 pub type UpvarListMap = FxHashMap<DefId, FxIndexMap<hir::HirId, UpvarId>>;
746 pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
748 #[derive(Clone, Copy, PartialEq, Eq)]
749 pub enum IntVarValue {
751 UintType(ast::UintTy),
754 #[derive(Clone, Copy, PartialEq, Eq)]
755 pub struct FloatVarValue(pub ast::FloatTy);
757 impl ty::EarlyBoundRegion {
758 pub fn to_bound_region(&self) -> ty::BoundRegion {
759 ty::BoundRegion::BrNamed(self.def_id, self.name)
762 /// Does this early bound region have a name? Early bound regions normally
763 /// always have names except when using anonymous lifetimes (`'_`).
764 pub fn has_name(&self) -> bool {
765 self.name != kw::UnderscoreLifetime
769 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
770 pub enum GenericParamDefKind {
774 object_lifetime_default: ObjectLifetimeDefault,
775 synthetic: Option<hir::SyntheticTyParamKind>,
780 impl GenericParamDefKind {
781 pub fn descr(&self) -> &'static str {
783 GenericParamDefKind::Lifetime => "lifetime",
784 GenericParamDefKind::Type { .. } => "type",
785 GenericParamDefKind::Const => "constant",
790 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
791 pub struct GenericParamDef {
796 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
797 /// on generic parameter `'a`/`T`, asserts data behind the parameter
798 /// `'a`/`T` won't be accessed during the parent type's `Drop` impl.
799 pub pure_wrt_drop: bool,
801 pub kind: GenericParamDefKind,
804 impl GenericParamDef {
805 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
806 if let GenericParamDefKind::Lifetime = self.kind {
807 ty::EarlyBoundRegion { def_id: self.def_id, index: self.index, name: self.name }
809 bug!("cannot convert a non-lifetime parameter def to an early bound region")
813 pub fn to_bound_region(&self) -> ty::BoundRegion {
814 if let GenericParamDefKind::Lifetime = self.kind {
815 self.to_early_bound_region_data().to_bound_region()
817 bug!("cannot convert a non-lifetime parameter def to an early bound region")
823 pub struct GenericParamCount {
824 pub lifetimes: usize,
829 /// Information about the formal type/lifetime parameters associated
830 /// with an item or method. Analogous to `hir::Generics`.
832 /// The ordering of parameters is the same as in `Subst` (excluding child generics):
833 /// `Self` (optionally), `Lifetime` params..., `Type` params...
834 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
835 pub struct Generics {
836 pub parent: Option<DefId>,
837 pub parent_count: usize,
838 pub params: Vec<GenericParamDef>,
840 /// Reverse map to the `index` field of each `GenericParamDef`.
841 #[stable_hasher(ignore)]
842 pub param_def_id_to_index: FxHashMap<DefId, u32>,
845 pub has_late_bound_regions: Option<Span>,
848 impl<'tcx> Generics {
849 pub fn count(&self) -> usize {
850 self.parent_count + self.params.len()
853 pub fn own_counts(&self) -> GenericParamCount {
854 // We could cache this as a property of `GenericParamCount`, but
855 // the aim is to refactor this away entirely eventually and the
856 // presence of this method will be a constant reminder.
857 let mut own_counts: GenericParamCount = Default::default();
859 for param in &self.params {
861 GenericParamDefKind::Lifetime => own_counts.lifetimes += 1,
862 GenericParamDefKind::Type { .. } => own_counts.types += 1,
863 GenericParamDefKind::Const => own_counts.consts += 1,
870 pub fn requires_monomorphization(&self, tcx: TyCtxt<'tcx>) -> bool {
871 if self.own_requires_monomorphization() {
875 if let Some(parent_def_id) = self.parent {
876 let parent = tcx.generics_of(parent_def_id);
877 parent.requires_monomorphization(tcx)
883 pub fn own_requires_monomorphization(&self) -> bool {
884 for param in &self.params {
886 GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true,
887 GenericParamDefKind::Lifetime => {}
893 /// Returns the `GenericParamDef` with the given index.
894 pub fn param_at(&'tcx self, param_index: usize, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
895 if let Some(index) = param_index.checked_sub(self.parent_count) {
898 tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?"))
899 .param_at(param_index, tcx)
903 /// Returns the `GenericParamDef` associated with this `EarlyBoundRegion`.
906 param: &EarlyBoundRegion,
908 ) -> &'tcx GenericParamDef {
909 let param = self.param_at(param.index as usize, tcx);
911 GenericParamDefKind::Lifetime => param,
912 _ => bug!("expected lifetime parameter, but found another generic parameter"),
916 /// Returns the `GenericParamDef` associated with this `ParamTy`.
917 pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
918 let param = self.param_at(param.index as usize, tcx);
920 GenericParamDefKind::Type { .. } => param,
921 _ => bug!("expected type parameter, but found another generic parameter"),
925 /// Returns the `GenericParamDef` associated with this `ParamConst`.
926 pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef {
927 let param = self.param_at(param.index as usize, tcx);
929 GenericParamDefKind::Const => param,
930 _ => bug!("expected const parameter, but found another generic parameter"),
935 /// Bounds on generics.
936 #[derive(Copy, Clone, Default, Debug, RustcEncodable, RustcDecodable, HashStable)]
937 pub struct GenericPredicates<'tcx> {
938 pub parent: Option<DefId>,
939 pub predicates: &'tcx [(Predicate<'tcx>, Span)],
942 impl<'tcx> GenericPredicates<'tcx> {
946 substs: SubstsRef<'tcx>,
947 ) -> InstantiatedPredicates<'tcx> {
948 let mut instantiated = InstantiatedPredicates::empty();
949 self.instantiate_into(tcx, &mut instantiated, substs);
953 pub fn instantiate_own(
956 substs: SubstsRef<'tcx>,
957 ) -> InstantiatedPredicates<'tcx> {
958 InstantiatedPredicates {
959 predicates: self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)).collect(),
960 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
967 instantiated: &mut InstantiatedPredicates<'tcx>,
968 substs: SubstsRef<'tcx>,
970 if let Some(def_id) = self.parent {
971 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
973 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)));
974 instantiated.spans.extend(self.predicates.iter().map(|(_, sp)| *sp));
977 pub fn instantiate_identity(&self, tcx: TyCtxt<'tcx>) -> InstantiatedPredicates<'tcx> {
978 let mut instantiated = InstantiatedPredicates::empty();
979 self.instantiate_identity_into(tcx, &mut instantiated);
983 fn instantiate_identity_into(
986 instantiated: &mut InstantiatedPredicates<'tcx>,
988 if let Some(def_id) = self.parent {
989 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
991 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p));
992 instantiated.spans.extend(self.predicates.iter().map(|(_, s)| s));
995 pub fn instantiate_supertrait(
998 poly_trait_ref: &ty::PolyTraitRef<'tcx>,
999 ) -> InstantiatedPredicates<'tcx> {
1000 assert_eq!(self.parent, None);
1001 InstantiatedPredicates {
1005 .map(|(pred, _)| pred.subst_supertrait(tcx, poly_trait_ref))
1007 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
1013 crate struct PredicateInner<'tcx> {
1014 kind: PredicateKind<'tcx>,
1016 /// See the comment for the corresponding field of [TyS].
1017 outer_exclusive_binder: ty::DebruijnIndex,
1020 #[cfg(target_arch = "x86_64")]
1021 static_assert_size!(PredicateInner<'_>, 40);
1023 #[derive(Clone, Copy, Lift)]
1024 pub struct Predicate<'tcx> {
1025 inner: &'tcx PredicateInner<'tcx>,
1028 impl rustc_serialize::UseSpecializedEncodable for Predicate<'_> {}
1029 impl rustc_serialize::UseSpecializedDecodable for Predicate<'_> {}
1031 impl<'tcx> PartialEq for Predicate<'tcx> {
1032 fn eq(&self, other: &Self) -> bool {
1033 // `self.kind` is always interned.
1034 ptr::eq(self.inner, other.inner)
1038 impl Hash for Predicate<'_> {
1039 fn hash<H: Hasher>(&self, s: &mut H) {
1040 (self.inner as *const PredicateInner<'_>).hash(s)
1044 impl<'tcx> Eq for Predicate<'tcx> {}
1046 impl<'tcx> Predicate<'tcx> {
1048 pub fn kind(self) -> &'tcx PredicateKind<'tcx> {
1053 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
1054 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1055 let PredicateInner {
1058 // The other fields just provide fast access to information that is
1059 // also contained in `kind`, so no need to hash them.
1061 outer_exclusive_binder: _,
1064 kind.hash_stable(hcx, hasher);
1068 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1069 #[derive(HashStable, TypeFoldable)]
1070 pub enum PredicateKind<'tcx> {
1071 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
1072 /// the `Self` type of the trait reference and `A`, `B`, and `C`
1073 /// would be the type parameters.
1075 /// A trait predicate will have `Constness::Const` if it originates
1076 /// from a bound on a `const fn` without the `?const` opt-out (e.g.,
1077 /// `const fn foobar<Foo: Bar>() {}`).
1078 Trait(PolyTraitPredicate<'tcx>, Constness),
1081 RegionOutlives(PolyRegionOutlivesPredicate<'tcx>),
1084 TypeOutlives(PolyTypeOutlivesPredicate<'tcx>),
1086 /// `where <T as TraitRef>::Name == X`, approximately.
1087 /// See the `ProjectionPredicate` struct for details.
1088 Projection(PolyProjectionPredicate<'tcx>),
1090 /// No syntax: `T` well-formed.
1091 WellFormed(GenericArg<'tcx>),
1093 /// Trait must be object-safe.
1096 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
1097 /// for some substitutions `...` and `T` being a closure type.
1098 /// Satisfied (or refuted) once we know the closure's kind.
1099 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
1102 Subtype(PolySubtypePredicate<'tcx>),
1104 /// Constant initializer must evaluate successfully.
1105 ConstEvaluatable(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>),
1107 /// Constants must be equal. The first component is the const that is expected.
1108 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
1111 /// The crate outlives map is computed during typeck and contains the
1112 /// outlives of every item in the local crate. You should not use it
1113 /// directly, because to do so will make your pass dependent on the
1114 /// HIR of every item in the local crate. Instead, use
1115 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
1117 #[derive(HashStable)]
1118 pub struct CratePredicatesMap<'tcx> {
1119 /// For each struct with outlive bounds, maps to a vector of the
1120 /// predicate of its outlive bounds. If an item has no outlives
1121 /// bounds, it will have no entry.
1122 pub predicates: FxHashMap<DefId, &'tcx [(ty::Predicate<'tcx>, Span)]>,
1125 impl<'tcx> Predicate<'tcx> {
1126 /// Performs a substitution suitable for going from a
1127 /// poly-trait-ref to supertraits that must hold if that
1128 /// poly-trait-ref holds. This is slightly different from a normal
1129 /// substitution in terms of what happens with bound regions. See
1130 /// lengthy comment below for details.
1131 pub fn subst_supertrait(
1134 trait_ref: &ty::PolyTraitRef<'tcx>,
1135 ) -> ty::Predicate<'tcx> {
1136 // The interaction between HRTB and supertraits is not entirely
1137 // obvious. Let me walk you (and myself) through an example.
1139 // Let's start with an easy case. Consider two traits:
1141 // trait Foo<'a>: Bar<'a,'a> { }
1142 // trait Bar<'b,'c> { }
1144 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
1145 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
1146 // knew that `Foo<'x>` (for any 'x) then we also know that
1147 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
1148 // normal substitution.
1150 // In terms of why this is sound, the idea is that whenever there
1151 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
1152 // holds. So if there is an impl of `T:Foo<'a>` that applies to
1153 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
1156 // Another example to be careful of is this:
1158 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
1159 // trait Bar1<'b,'c> { }
1161 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
1162 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
1163 // reason is similar to the previous example: any impl of
1164 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
1165 // basically we would want to collapse the bound lifetimes from
1166 // the input (`trait_ref`) and the supertraits.
1168 // To achieve this in practice is fairly straightforward. Let's
1169 // consider the more complicated scenario:
1171 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
1172 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
1173 // where both `'x` and `'b` would have a DB index of 1.
1174 // The substitution from the input trait-ref is therefore going to be
1175 // `'a => 'x` (where `'x` has a DB index of 1).
1176 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1177 // early-bound parameter and `'b' is a late-bound parameter with a
1179 // - If we replace `'a` with `'x` from the input, it too will have
1180 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1181 // just as we wanted.
1183 // There is only one catch. If we just apply the substitution `'a
1184 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1185 // adjust the DB index because we substituting into a binder (it
1186 // tries to be so smart...) resulting in `for<'x> for<'b>
1187 // Bar1<'x,'b>` (we have no syntax for this, so use your
1188 // imagination). Basically the 'x will have DB index of 2 and 'b
1189 // will have DB index of 1. Not quite what we want. So we apply
1190 // the substitution to the *contents* of the trait reference,
1191 // rather than the trait reference itself (put another way, the
1192 // substitution code expects equal binding levels in the values
1193 // from the substitution and the value being substituted into, and
1194 // this trick achieves that).
1196 let substs = &trait_ref.skip_binder().substs;
1197 let kind = self.kind();
1198 let new = match kind {
1199 &PredicateKind::Trait(ref binder, constness) => {
1200 PredicateKind::Trait(binder.map_bound(|data| data.subst(tcx, substs)), constness)
1202 PredicateKind::Subtype(binder) => {
1203 PredicateKind::Subtype(binder.map_bound(|data| data.subst(tcx, substs)))
1205 PredicateKind::RegionOutlives(binder) => {
1206 PredicateKind::RegionOutlives(binder.map_bound(|data| data.subst(tcx, substs)))
1208 PredicateKind::TypeOutlives(binder) => {
1209 PredicateKind::TypeOutlives(binder.map_bound(|data| data.subst(tcx, substs)))
1211 PredicateKind::Projection(binder) => {
1212 PredicateKind::Projection(binder.map_bound(|data| data.subst(tcx, substs)))
1214 &PredicateKind::WellFormed(data) => PredicateKind::WellFormed(data.subst(tcx, substs)),
1215 &PredicateKind::ObjectSafe(trait_def_id) => PredicateKind::ObjectSafe(trait_def_id),
1216 &PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
1217 PredicateKind::ClosureKind(closure_def_id, closure_substs.subst(tcx, substs), kind)
1219 &PredicateKind::ConstEvaluatable(def_id, const_substs) => {
1220 PredicateKind::ConstEvaluatable(def_id, const_substs.subst(tcx, substs))
1222 PredicateKind::ConstEquate(c1, c2) => {
1223 PredicateKind::ConstEquate(c1.subst(tcx, substs), c2.subst(tcx, substs))
1227 if new != *kind { new.to_predicate(tcx) } else { self }
1231 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1232 #[derive(HashStable, TypeFoldable)]
1233 pub struct TraitPredicate<'tcx> {
1234 pub trait_ref: TraitRef<'tcx>,
1237 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1239 impl<'tcx> TraitPredicate<'tcx> {
1240 pub fn def_id(self) -> DefId {
1241 self.trait_ref.def_id
1244 pub fn self_ty(self) -> Ty<'tcx> {
1245 self.trait_ref.self_ty()
1249 impl<'tcx> PolyTraitPredicate<'tcx> {
1250 pub fn def_id(self) -> DefId {
1251 // Ok to skip binder since trait `DefId` does not care about regions.
1252 self.skip_binder().def_id()
1256 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1257 #[derive(HashStable, TypeFoldable)]
1258 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
1259 pub type PolyOutlivesPredicate<A, B> = ty::Binder<OutlivesPredicate<A, B>>;
1260 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
1261 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1262 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>;
1263 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>;
1265 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1266 #[derive(HashStable, TypeFoldable)]
1267 pub struct SubtypePredicate<'tcx> {
1268 pub a_is_expected: bool,
1272 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1274 /// This kind of predicate has no *direct* correspondent in the
1275 /// syntax, but it roughly corresponds to the syntactic forms:
1277 /// 1. `T: TraitRef<..., Item = Type>`
1278 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1280 /// In particular, form #1 is "desugared" to the combination of a
1281 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1282 /// predicates. Form #2 is a broader form in that it also permits
1283 /// equality between arbitrary types. Processing an instance of
1284 /// Form #2 eventually yields one of these `ProjectionPredicate`
1285 /// instances to normalize the LHS.
1286 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1287 #[derive(HashStable, TypeFoldable)]
1288 pub struct ProjectionPredicate<'tcx> {
1289 pub projection_ty: ProjectionTy<'tcx>,
1293 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1295 impl<'tcx> PolyProjectionPredicate<'tcx> {
1296 /// Returns the `DefId` of the associated item being projected.
1297 pub fn item_def_id(&self) -> DefId {
1298 self.skip_binder().projection_ty.item_def_id
1302 pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
1303 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1304 // `self.0.trait_ref` is permitted to have escaping regions.
1305 // This is because here `self` has a `Binder` and so does our
1306 // return value, so we are preserving the number of binding
1308 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1311 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1312 self.map_bound(|predicate| predicate.ty)
1315 /// The `DefId` of the `TraitItem` for the associated type.
1317 /// Note that this is not the `DefId` of the `TraitRef` containing this
1318 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1319 pub fn projection_def_id(&self) -> DefId {
1320 // Ok to skip binder since trait `DefId` does not care about regions.
1321 self.skip_binder().projection_ty.item_def_id
1325 pub trait ToPolyTraitRef<'tcx> {
1326 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1329 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1330 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1331 ty::Binder::dummy(*self)
1335 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1336 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1337 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1341 pub trait ToPredicate<'tcx> {
1342 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
1345 impl ToPredicate<'tcx> for PredicateKind<'tcx> {
1347 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1348 tcx.mk_predicate(self)
1352 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<TraitRef<'tcx>> {
1353 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1354 ty::PredicateKind::Trait(
1355 ty::Binder::dummy(ty::TraitPredicate { trait_ref: self.value }),
1362 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<&TraitRef<'tcx>> {
1363 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1364 ty::PredicateKind::Trait(
1365 ty::Binder::dummy(ty::TraitPredicate { trait_ref: *self.value }),
1372 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> {
1373 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1374 ty::PredicateKind::Trait(self.value.to_poly_trait_predicate(), self.constness)
1379 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<&PolyTraitRef<'tcx>> {
1380 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1381 ty::PredicateKind::Trait(self.value.to_poly_trait_predicate(), self.constness)
1386 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1387 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1388 PredicateKind::RegionOutlives(self).to_predicate(tcx)
1392 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1393 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1394 PredicateKind::TypeOutlives(self).to_predicate(tcx)
1398 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1399 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1400 PredicateKind::Projection(self).to_predicate(tcx)
1404 impl<'tcx> Predicate<'tcx> {
1405 pub fn to_opt_poly_trait_ref(self) -> Option<PolyTraitRef<'tcx>> {
1407 &PredicateKind::Trait(ref t, _) => Some(t.to_poly_trait_ref()),
1408 PredicateKind::Projection(..)
1409 | PredicateKind::Subtype(..)
1410 | PredicateKind::RegionOutlives(..)
1411 | PredicateKind::WellFormed(..)
1412 | PredicateKind::ObjectSafe(..)
1413 | PredicateKind::ClosureKind(..)
1414 | PredicateKind::TypeOutlives(..)
1415 | PredicateKind::ConstEvaluatable(..)
1416 | PredicateKind::ConstEquate(..) => None,
1420 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1422 &PredicateKind::TypeOutlives(data) => Some(data),
1423 PredicateKind::Trait(..)
1424 | PredicateKind::Projection(..)
1425 | PredicateKind::Subtype(..)
1426 | PredicateKind::RegionOutlives(..)
1427 | PredicateKind::WellFormed(..)
1428 | PredicateKind::ObjectSafe(..)
1429 | PredicateKind::ClosureKind(..)
1430 | PredicateKind::ConstEvaluatable(..)
1431 | PredicateKind::ConstEquate(..) => None,
1436 /// Represents the bounds declared on a particular set of type
1437 /// parameters. Should eventually be generalized into a flag list of
1438 /// where-clauses. You can obtain a `InstantiatedPredicates` list from a
1439 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1440 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1441 /// the `GenericPredicates` are expressed in terms of the bound type
1442 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1443 /// represented a set of bounds for some particular instantiation,
1444 /// meaning that the generic parameters have been substituted with
1449 /// struct Foo<T, U: Bar<T>> { ... }
1451 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1452 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1453 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1454 /// [usize:Bar<isize>]]`.
1455 #[derive(Clone, Debug, TypeFoldable)]
1456 pub struct InstantiatedPredicates<'tcx> {
1457 pub predicates: Vec<Predicate<'tcx>>,
1458 pub spans: Vec<Span>,
1461 impl<'tcx> InstantiatedPredicates<'tcx> {
1462 pub fn empty() -> InstantiatedPredicates<'tcx> {
1463 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1466 pub fn is_empty(&self) -> bool {
1467 self.predicates.is_empty()
1471 rustc_index::newtype_index! {
1472 /// "Universes" are used during type- and trait-checking in the
1473 /// presence of `for<..>` binders to control what sets of names are
1474 /// visible. Universes are arranged into a tree: the root universe
1475 /// contains names that are always visible. Each child then adds a new
1476 /// set of names that are visible, in addition to those of its parent.
1477 /// We say that the child universe "extends" the parent universe with
1480 /// To make this more concrete, consider this program:
1484 /// fn bar<T>(x: T) {
1485 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1489 /// The struct name `Foo` is in the root universe U0. But the type
1490 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1491 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1492 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1493 /// region `'a` is in a universe U2 that extends U1, because we can
1494 /// name it inside the fn type but not outside.
1496 /// Universes are used to do type- and trait-checking around these
1497 /// "forall" binders (also called **universal quantification**). The
1498 /// idea is that when, in the body of `bar`, we refer to `T` as a
1499 /// type, we aren't referring to any type in particular, but rather a
1500 /// kind of "fresh" type that is distinct from all other types we have
1501 /// actually declared. This is called a **placeholder** type, and we
1502 /// use universes to talk about this. In other words, a type name in
1503 /// universe 0 always corresponds to some "ground" type that the user
1504 /// declared, but a type name in a non-zero universe is a placeholder
1505 /// type -- an idealized representative of "types in general" that we
1506 /// use for checking generic functions.
1507 pub struct UniverseIndex {
1509 DEBUG_FORMAT = "U{}",
1513 impl UniverseIndex {
1514 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1516 /// Returns the "next" universe index in order -- this new index
1517 /// is considered to extend all previous universes. This
1518 /// corresponds to entering a `forall` quantifier. So, for
1519 /// example, suppose we have this type in universe `U`:
1522 /// for<'a> fn(&'a u32)
1525 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1526 /// new universe that extends `U` -- in this new universe, we can
1527 /// name the region `'a`, but that region was not nameable from
1528 /// `U` because it was not in scope there.
1529 pub fn next_universe(self) -> UniverseIndex {
1530 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1533 /// Returns `true` if `self` can name a name from `other` -- in other words,
1534 /// if the set of names in `self` is a superset of those in
1535 /// `other` (`self >= other`).
1536 pub fn can_name(self, other: UniverseIndex) -> bool {
1537 self.private >= other.private
1540 /// Returns `true` if `self` cannot name some names from `other` -- in other
1541 /// words, if the set of names in `self` is a strict subset of
1542 /// those in `other` (`self < other`).
1543 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1544 self.private < other.private
1548 /// The "placeholder index" fully defines a placeholder region.
1549 /// Placeholder regions are identified by both a **universe** as well
1550 /// as a "bound-region" within that universe. The `bound_region` is
1551 /// basically a name -- distinct bound regions within the same
1552 /// universe are just two regions with an unknown relationship to one
1554 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1555 pub struct Placeholder<T> {
1556 pub universe: UniverseIndex,
1560 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1562 T: HashStable<StableHashingContext<'a>>,
1564 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1565 self.universe.hash_stable(hcx, hasher);
1566 self.name.hash_stable(hcx, hasher);
1570 pub type PlaceholderRegion = Placeholder<BoundRegion>;
1572 pub type PlaceholderType = Placeholder<BoundVar>;
1574 pub type PlaceholderConst = Placeholder<BoundVar>;
1576 /// A `DefId` which is potentially bundled with its corresponding generic parameter
1577 /// in case `did` is a const argument.
1579 /// This is used to prevent cycle errors during typeck
1580 /// as `type_of(const_arg)` depends on `typeck(owning_body)`
1581 /// which once again requires the type of its generic arguments.
1583 /// Luckily we only need to deal with const arguments once we
1584 /// know their corresponding parameters. We (ab)use this by
1585 /// calling `type_of(param_did)` for these arguments.
1588 /// #![feature(const_generics)]
1592 /// fn foo<const N: usize>(&self) -> usize { N }
1596 /// fn foo<const N: u8>(&self) -> usize { 42 }
1604 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, RustcEncodable, RustcDecodable)]
1605 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1606 #[derive(Hash, HashStable)]
1607 pub struct WithOptConstParam<T> {
1609 /// The `DefId` of the corresponding generic paramter in case `did` is
1610 /// a const argument.
1612 /// Note that even if `did` is a const argument, this may still be `None`.
1613 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1614 /// to potentially update `param_did` in case it `None`.
1615 pub const_param_did: Option<DefId>,
1618 impl<T> WithOptConstParam<T> {
1619 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1621 pub fn unknown(did: T) -> WithOptConstParam<T> {
1622 WithOptConstParam { did, const_param_did: None }
1626 impl WithOptConstParam<LocalDefId> {
1627 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1628 /// `None` otherwise.
1630 pub fn try_fetch(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1631 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1634 /// In case `self` is unknown but `self.did` is a const argument, this returns
1635 /// a `WithOptConstParam` with the correct `const_param_did`.
1637 pub fn try_update(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1638 if self.const_param_did.is_none() {
1639 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1640 return Some(WithOptConstParam { did: self.did, const_param_did });
1647 pub fn to_global(self) -> WithOptConstParam<DefId> {
1648 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1651 pub fn def_id_for_type_of(self) -> DefId {
1652 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1656 impl WithOptConstParam<DefId> {
1657 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1660 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1663 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1664 if let Some(param_did) = self.const_param_did {
1665 if let Some(did) = self.did.as_local() {
1666 return Some((did, param_did));
1673 pub fn expect_local(self) -> WithOptConstParam<LocalDefId> {
1674 self.as_local().unwrap()
1677 pub fn is_local(self) -> bool {
1681 pub fn def_id_for_type_of(self) -> DefId {
1682 self.const_param_did.unwrap_or(self.did)
1686 /// When type checking, we use the `ParamEnv` to track
1687 /// details about the set of where-clauses that are in scope at this
1688 /// particular point.
1689 #[derive(Copy, Clone)]
1690 pub struct ParamEnv<'tcx> {
1691 // We pack the caller_bounds List pointer and a Reveal enum into this usize.
1692 // Specifically, the low bit represents Reveal, with 0 meaning `UserFacing`
1693 // and 1 meaning `All`. The rest is the pointer.
1695 // This relies on the List<ty::Predicate<'tcx>> type having at least 2-byte
1696 // alignment. Lists start with a usize and are repr(C) so this should be
1697 // fine; there is a debug_assert in the constructor as well.
1699 // Note that the choice of 0 for UserFacing is intentional -- since it is the
1700 // first variant in Reveal this means that joining the pointer is a simple `or`.
1703 /// `Obligation`s that the caller must satisfy. This is basically
1704 /// the set of bounds on the in-scope type parameters, translated
1705 /// into `Obligation`s, and elaborated and normalized.
1707 /// Note: This is packed into the `packed_data` usize above, use the
1708 /// `caller_bounds()` method to access it.
1709 caller_bounds: PhantomData<&'tcx List<ty::Predicate<'tcx>>>,
1711 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1712 /// want `Reveal::All`.
1714 /// Note: This is packed into the caller_bounds usize above, use the reveal()
1715 /// method to access it.
1716 reveal: PhantomData<traits::Reveal>,
1718 /// If this `ParamEnv` comes from a call to `tcx.param_env(def_id)`,
1719 /// register that `def_id` (useful for transitioning to the chalk trait
1721 pub def_id: Option<DefId>,
1724 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1725 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1726 f.debug_struct("ParamEnv")
1727 .field("caller_bounds", &self.caller_bounds())
1728 .field("reveal", &self.reveal())
1729 .field("def_id", &self.def_id)
1734 impl<'tcx> Hash for ParamEnv<'tcx> {
1735 fn hash<H: Hasher>(&self, state: &mut H) {
1736 // List hashes as the raw pointer, so we can skip splitting into the
1737 // pointer and the enum.
1738 self.packed_data.hash(state);
1739 self.def_id.hash(state);
1743 impl<'tcx> PartialEq for ParamEnv<'tcx> {
1744 fn eq(&self, other: &Self) -> bool {
1745 self.caller_bounds() == other.caller_bounds()
1746 && self.reveal() == other.reveal()
1747 && self.def_id == other.def_id
1750 impl<'tcx> Eq for ParamEnv<'tcx> {}
1752 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1753 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1754 self.caller_bounds().hash_stable(hcx, hasher);
1755 self.reveal().hash_stable(hcx, hasher);
1756 self.def_id.hash_stable(hcx, hasher);
1760 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1761 fn super_fold_with<F: ty::fold::TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1763 self.caller_bounds().fold_with(folder),
1764 self.reveal().fold_with(folder),
1765 self.def_id.fold_with(folder),
1769 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1770 self.caller_bounds().visit_with(visitor)
1771 || self.reveal().visit_with(visitor)
1772 || self.def_id.visit_with(visitor)
1776 impl<'tcx> ParamEnv<'tcx> {
1777 /// Construct a trait environment suitable for contexts where
1778 /// there are no where-clauses in scope. Hidden types (like `impl
1779 /// Trait`) are left hidden, so this is suitable for ordinary
1782 pub fn empty() -> Self {
1783 Self::new(List::empty(), Reveal::UserFacing, None)
1787 pub fn caller_bounds(self) -> &'tcx List<ty::Predicate<'tcx>> {
1788 // mask out bottom bit
1789 unsafe { &*((self.packed_data & (!1)) as *const _) }
1793 pub fn reveal(self) -> traits::Reveal {
1794 if self.packed_data & 1 == 0 { traits::Reveal::UserFacing } else { traits::Reveal::All }
1797 /// Construct a trait environment with no where-clauses in scope
1798 /// where the values of all `impl Trait` and other hidden types
1799 /// are revealed. This is suitable for monomorphized, post-typeck
1800 /// environments like codegen or doing optimizations.
1802 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1803 /// or invoke `param_env.with_reveal_all()`.
1805 pub fn reveal_all() -> Self {
1806 Self::new(List::empty(), Reveal::All, None)
1809 /// Construct a trait environment with the given set of predicates.
1812 caller_bounds: &'tcx List<ty::Predicate<'tcx>>,
1814 def_id: Option<DefId>,
1816 let packed_data = caller_bounds as *const _ as usize;
1817 // Check that we can pack the reveal data into the pointer.
1818 debug_assert!(packed_data & 1 == 0);
1820 packed_data: packed_data
1822 Reveal::UserFacing => 0,
1825 caller_bounds: PhantomData,
1826 reveal: PhantomData,
1831 pub fn with_user_facing(mut self) -> Self {
1833 self.packed_data &= !1;
1837 /// Returns a new parameter environment with the same clauses, but
1838 /// which "reveals" the true results of projections in all cases
1839 /// (even for associated types that are specializable). This is
1840 /// the desired behavior during codegen and certain other special
1841 /// contexts; normally though we want to use `Reveal::UserFacing`,
1842 /// which is the default.
1843 pub fn with_reveal_all(mut self) -> Self {
1844 self.packed_data |= 1;
1848 /// Returns this same environment but with no caller bounds.
1849 pub fn without_caller_bounds(self) -> Self {
1850 Self::new(List::empty(), self.reveal(), self.def_id)
1853 /// Creates a suitable environment in which to perform trait
1854 /// queries on the given value. When type-checking, this is simply
1855 /// the pair of the environment plus value. But when reveal is set to
1856 /// All, then if `value` does not reference any type parameters, we will
1857 /// pair it with the empty environment. This improves caching and is generally
1860 /// N.B., we preserve the environment when type-checking because it
1861 /// is possible for the user to have wacky where-clauses like
1862 /// `where Box<u32>: Copy`, which are clearly never
1863 /// satisfiable. We generally want to behave as if they were true,
1864 /// although the surrounding function is never reachable.
1865 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1866 match self.reveal() {
1867 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1870 if value.is_global() {
1871 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1873 ParamEnvAnd { param_env: self, value }
1880 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1881 pub struct ConstnessAnd<T> {
1882 pub constness: Constness,
1886 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1887 // the constness of trait bounds is being propagated correctly.
1888 pub trait WithConstness: Sized {
1890 fn with_constness(self, constness: Constness) -> ConstnessAnd<Self> {
1891 ConstnessAnd { constness, value: self }
1895 fn with_const(self) -> ConstnessAnd<Self> {
1896 self.with_constness(Constness::Const)
1900 fn without_const(self) -> ConstnessAnd<Self> {
1901 self.with_constness(Constness::NotConst)
1905 impl<T> WithConstness for T {}
1907 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1908 pub struct ParamEnvAnd<'tcx, T> {
1909 pub param_env: ParamEnv<'tcx>,
1913 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1914 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1915 (self.param_env, self.value)
1919 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1921 T: HashStable<StableHashingContext<'a>>,
1923 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1924 let ParamEnvAnd { ref param_env, ref value } = *self;
1926 param_env.hash_stable(hcx, hasher);
1927 value.hash_stable(hcx, hasher);
1931 #[derive(Copy, Clone, Debug, HashStable)]
1932 pub struct Destructor {
1933 /// The `DefId` of the destructor method
1938 #[derive(HashStable)]
1939 pub struct AdtFlags: u32 {
1940 const NO_ADT_FLAGS = 0;
1941 /// Indicates whether the ADT is an enum.
1942 const IS_ENUM = 1 << 0;
1943 /// Indicates whether the ADT is a union.
1944 const IS_UNION = 1 << 1;
1945 /// Indicates whether the ADT is a struct.
1946 const IS_STRUCT = 1 << 2;
1947 /// Indicates whether the ADT is a struct and has a constructor.
1948 const HAS_CTOR = 1 << 3;
1949 /// Indicates whether the type is `PhantomData`.
1950 const IS_PHANTOM_DATA = 1 << 4;
1951 /// Indicates whether the type has a `#[fundamental]` attribute.
1952 const IS_FUNDAMENTAL = 1 << 5;
1953 /// Indicates whether the type is `Box`.
1954 const IS_BOX = 1 << 6;
1955 /// Indicates whether the type is `ManuallyDrop`.
1956 const IS_MANUALLY_DROP = 1 << 7;
1957 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
1958 /// (i.e., this flag is never set unless this ADT is an enum).
1959 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
1964 #[derive(HashStable)]
1965 pub struct VariantFlags: u32 {
1966 const NO_VARIANT_FLAGS = 0;
1967 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1968 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1972 /// Definition of a variant -- a struct's fields or a enum variant.
1973 #[derive(Debug, HashStable)]
1974 pub struct VariantDef {
1975 /// `DefId` that identifies the variant itself.
1976 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1978 /// `DefId` that identifies the variant's constructor.
1979 /// If this variant is a struct variant, then this is `None`.
1980 pub ctor_def_id: Option<DefId>,
1981 /// Variant or struct name.
1982 #[stable_hasher(project(name))]
1984 /// Discriminant of this variant.
1985 pub discr: VariantDiscr,
1986 /// Fields of this variant.
1987 pub fields: Vec<FieldDef>,
1988 /// Type of constructor of variant.
1989 pub ctor_kind: CtorKind,
1990 /// Flags of the variant (e.g. is field list non-exhaustive)?
1991 flags: VariantFlags,
1992 /// Variant is obtained as part of recovering from a syntactic error.
1993 /// May be incomplete or bogus.
1994 pub recovered: bool,
1997 impl<'tcx> VariantDef {
1998 /// Creates a new `VariantDef`.
2000 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
2001 /// represents an enum variant).
2003 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
2004 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
2006 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
2007 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
2008 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
2009 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
2010 /// built-in trait), and we do not want to load attributes twice.
2012 /// If someone speeds up attribute loading to not be a performance concern, they can
2013 /// remove this hack and use the constructor `DefId` everywhere.
2017 variant_did: Option<DefId>,
2018 ctor_def_id: Option<DefId>,
2019 discr: VariantDiscr,
2020 fields: Vec<FieldDef>,
2021 ctor_kind: CtorKind,
2027 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
2028 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
2029 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
2032 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
2033 if adt_kind == AdtKind::Struct && tcx.has_attr(parent_did, sym::non_exhaustive) {
2034 debug!("found non-exhaustive field list for {:?}", parent_did);
2035 flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
2036 } else if let Some(variant_did) = variant_did {
2037 if tcx.has_attr(variant_did, sym::non_exhaustive) {
2038 debug!("found non-exhaustive field list for {:?}", variant_did);
2039 flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
2044 def_id: variant_did.unwrap_or(parent_did),
2055 /// Is this field list non-exhaustive?
2057 pub fn is_field_list_non_exhaustive(&self) -> bool {
2058 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
2061 /// `repr(transparent)` structs can have a single non-ZST field, this function returns that
2063 pub fn transparent_newtype_field(&self, tcx: TyCtxt<'tcx>) -> Option<&FieldDef> {
2064 for field in &self.fields {
2065 let field_ty = field.ty(tcx, InternalSubsts::identity_for_item(tcx, self.def_id));
2066 if !field_ty.is_zst(tcx, self.def_id) {
2075 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
2076 pub enum VariantDiscr {
2077 /// Explicit value for this variant, i.e., `X = 123`.
2078 /// The `DefId` corresponds to the embedded constant.
2081 /// The previous variant's discriminant plus one.
2082 /// For efficiency reasons, the distance from the
2083 /// last `Explicit` discriminant is being stored,
2084 /// or `0` for the first variant, if it has none.
2088 #[derive(Debug, HashStable)]
2089 pub struct FieldDef {
2091 #[stable_hasher(project(name))]
2093 pub vis: Visibility,
2096 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
2098 /// These are all interned (by `alloc_adt_def`) into the global arena.
2100 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
2101 /// This is slightly wrong because `union`s are not ADTs.
2102 /// Moreover, Rust only allows recursive data types through indirection.
2104 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
2106 /// The `DefId` of the struct, enum or union item.
2108 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
2109 pub variants: IndexVec<VariantIdx, VariantDef>,
2110 /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
2112 /// Repr options provided by the user.
2113 pub repr: ReprOptions,
2116 impl PartialOrd for AdtDef {
2117 fn partial_cmp(&self, other: &AdtDef) -> Option<Ordering> {
2118 Some(self.cmp(&other))
2122 /// There should be only one AdtDef for each `did`, therefore
2123 /// it is fine to implement `Ord` only based on `did`.
2124 impl Ord for AdtDef {
2125 fn cmp(&self, other: &AdtDef) -> Ordering {
2126 self.did.cmp(&other.did)
2130 impl PartialEq for AdtDef {
2131 // `AdtDef`s are always interned, and this is part of `TyS` equality.
2133 fn eq(&self, other: &Self) -> bool {
2134 ptr::eq(self, other)
2138 impl Eq for AdtDef {}
2140 impl Hash for AdtDef {
2142 fn hash<H: Hasher>(&self, s: &mut H) {
2143 (self as *const AdtDef).hash(s)
2147 impl<'tcx> rustc_serialize::UseSpecializedEncodable for &'tcx AdtDef {
2148 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
2153 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx AdtDef {}
2155 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
2156 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
2158 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default();
2161 let hash: Fingerprint = CACHE.with(|cache| {
2162 let addr = self as *const AdtDef as usize;
2163 *cache.borrow_mut().entry(addr).or_insert_with(|| {
2164 let ty::AdtDef { did, ref variants, ref flags, ref repr } = *self;
2166 let mut hasher = StableHasher::new();
2167 did.hash_stable(hcx, &mut hasher);
2168 variants.hash_stable(hcx, &mut hasher);
2169 flags.hash_stable(hcx, &mut hasher);
2170 repr.hash_stable(hcx, &mut hasher);
2176 hash.hash_stable(hcx, hasher);
2180 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
2187 impl Into<DataTypeKind> for AdtKind {
2188 fn into(self) -> DataTypeKind {
2190 AdtKind::Struct => DataTypeKind::Struct,
2191 AdtKind::Union => DataTypeKind::Union,
2192 AdtKind::Enum => DataTypeKind::Enum,
2198 #[derive(RustcEncodable, RustcDecodable, Default, HashStable)]
2199 pub struct ReprFlags: u8 {
2200 const IS_C = 1 << 0;
2201 const IS_SIMD = 1 << 1;
2202 const IS_TRANSPARENT = 1 << 2;
2203 // Internal only for now. If true, don't reorder fields.
2204 const IS_LINEAR = 1 << 3;
2205 // If true, don't expose any niche to type's context.
2206 const HIDE_NICHE = 1 << 4;
2207 // Any of these flags being set prevent field reordering optimisation.
2208 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
2209 ReprFlags::IS_SIMD.bits |
2210 ReprFlags::IS_LINEAR.bits;
2214 /// Represents the repr options provided by the user,
2215 #[derive(Copy, Clone, Debug, Eq, PartialEq, RustcEncodable, RustcDecodable, Default, HashStable)]
2216 pub struct ReprOptions {
2217 pub int: Option<attr::IntType>,
2218 pub align: Option<Align>,
2219 pub pack: Option<Align>,
2220 pub flags: ReprFlags,
2224 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
2225 let mut flags = ReprFlags::empty();
2226 let mut size = None;
2227 let mut max_align: Option<Align> = None;
2228 let mut min_pack: Option<Align> = None;
2229 for attr in tcx.get_attrs(did).iter() {
2230 for r in attr::find_repr_attrs(&tcx.sess.parse_sess, attr) {
2231 flags.insert(match r {
2232 attr::ReprC => ReprFlags::IS_C,
2233 attr::ReprPacked(pack) => {
2234 let pack = Align::from_bytes(pack as u64).unwrap();
2235 min_pack = Some(if let Some(min_pack) = min_pack {
2242 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2243 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
2244 attr::ReprSimd => ReprFlags::IS_SIMD,
2245 attr::ReprInt(i) => {
2249 attr::ReprAlign(align) => {
2250 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2257 // This is here instead of layout because the choice must make it into metadata.
2258 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2259 flags.insert(ReprFlags::IS_LINEAR);
2261 ReprOptions { int: size, align: max_align, pack: min_pack, flags }
2265 pub fn simd(&self) -> bool {
2266 self.flags.contains(ReprFlags::IS_SIMD)
2269 pub fn c(&self) -> bool {
2270 self.flags.contains(ReprFlags::IS_C)
2273 pub fn packed(&self) -> bool {
2277 pub fn transparent(&self) -> bool {
2278 self.flags.contains(ReprFlags::IS_TRANSPARENT)
2281 pub fn linear(&self) -> bool {
2282 self.flags.contains(ReprFlags::IS_LINEAR)
2285 pub fn hide_niche(&self) -> bool {
2286 self.flags.contains(ReprFlags::HIDE_NICHE)
2289 /// Returns the discriminant type, given these `repr` options.
2290 /// This must only be called on enums!
2291 pub fn discr_type(&self) -> attr::IntType {
2292 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2295 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2296 /// layout" optimizations, such as representing `Foo<&T>` as a
2298 pub fn inhibit_enum_layout_opt(&self) -> bool {
2299 self.c() || self.int.is_some()
2302 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2303 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2304 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2305 if let Some(pack) = self.pack {
2306 if pack.bytes() == 1 {
2310 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2313 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2314 pub fn inhibit_union_abi_opt(&self) -> bool {
2320 /// Creates a new `AdtDef`.
2325 variants: IndexVec<VariantIdx, VariantDef>,
2328 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
2329 let mut flags = AdtFlags::NO_ADT_FLAGS;
2331 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
2332 debug!("found non-exhaustive variant list for {:?}", did);
2333 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
2336 flags |= match kind {
2337 AdtKind::Enum => AdtFlags::IS_ENUM,
2338 AdtKind::Union => AdtFlags::IS_UNION,
2339 AdtKind::Struct => AdtFlags::IS_STRUCT,
2342 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
2343 flags |= AdtFlags::HAS_CTOR;
2346 let attrs = tcx.get_attrs(did);
2347 if attr::contains_name(&attrs, sym::fundamental) {
2348 flags |= AdtFlags::IS_FUNDAMENTAL;
2350 if Some(did) == tcx.lang_items().phantom_data() {
2351 flags |= AdtFlags::IS_PHANTOM_DATA;
2353 if Some(did) == tcx.lang_items().owned_box() {
2354 flags |= AdtFlags::IS_BOX;
2356 if Some(did) == tcx.lang_items().manually_drop() {
2357 flags |= AdtFlags::IS_MANUALLY_DROP;
2360 AdtDef { did, variants, flags, repr }
2363 /// Returns `true` if this is a struct.
2365 pub fn is_struct(&self) -> bool {
2366 self.flags.contains(AdtFlags::IS_STRUCT)
2369 /// Returns `true` if this is a union.
2371 pub fn is_union(&self) -> bool {
2372 self.flags.contains(AdtFlags::IS_UNION)
2375 /// Returns `true` if this is a enum.
2377 pub fn is_enum(&self) -> bool {
2378 self.flags.contains(AdtFlags::IS_ENUM)
2381 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
2383 pub fn is_variant_list_non_exhaustive(&self) -> bool {
2384 self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
2387 /// Returns the kind of the ADT.
2389 pub fn adt_kind(&self) -> AdtKind {
2392 } else if self.is_union() {
2399 /// Returns a description of this abstract data type.
2400 pub fn descr(&self) -> &'static str {
2401 match self.adt_kind() {
2402 AdtKind::Struct => "struct",
2403 AdtKind::Union => "union",
2404 AdtKind::Enum => "enum",
2408 /// Returns a description of a variant of this abstract data type.
2410 pub fn variant_descr(&self) -> &'static str {
2411 match self.adt_kind() {
2412 AdtKind::Struct => "struct",
2413 AdtKind::Union => "union",
2414 AdtKind::Enum => "variant",
2418 /// If this function returns `true`, it implies that `is_struct` must return `true`.
2420 pub fn has_ctor(&self) -> bool {
2421 self.flags.contains(AdtFlags::HAS_CTOR)
2424 /// Returns `true` if this type is `#[fundamental]` for the purposes
2425 /// of coherence checking.
2427 pub fn is_fundamental(&self) -> bool {
2428 self.flags.contains(AdtFlags::IS_FUNDAMENTAL)
2431 /// Returns `true` if this is `PhantomData<T>`.
2433 pub fn is_phantom_data(&self) -> bool {
2434 self.flags.contains(AdtFlags::IS_PHANTOM_DATA)
2437 /// Returns `true` if this is Box<T>.
2439 pub fn is_box(&self) -> bool {
2440 self.flags.contains(AdtFlags::IS_BOX)
2443 /// Returns `true` if this is `ManuallyDrop<T>`.
2445 pub fn is_manually_drop(&self) -> bool {
2446 self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
2449 /// Returns `true` if this type has a destructor.
2450 pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
2451 self.destructor(tcx).is_some()
2454 /// Asserts this is a struct or union and returns its unique variant.
2455 pub fn non_enum_variant(&self) -> &VariantDef {
2456 assert!(self.is_struct() || self.is_union());
2457 &self.variants[VariantIdx::new(0)]
2461 pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
2462 tcx.predicates_of(self.did)
2465 /// Returns an iterator over all fields contained
2468 pub fn all_fields(&self) -> impl Iterator<Item = &FieldDef> + Clone {
2469 self.variants.iter().flat_map(|v| v.fields.iter())
2472 pub fn is_payloadfree(&self) -> bool {
2473 !self.variants.is_empty() && self.variants.iter().all(|v| v.fields.is_empty())
2476 /// Return a `VariantDef` given a variant id.
2477 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
2478 self.variants.iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
2481 /// Return a `VariantDef` given a constructor id.
2482 pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
2485 .find(|v| v.ctor_def_id == Some(cid))
2486 .expect("variant_with_ctor_id: unknown variant")
2489 /// Return the index of `VariantDef` given a variant id.
2490 pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
2493 .find(|(_, v)| v.def_id == vid)
2494 .expect("variant_index_with_id: unknown variant")
2498 /// Return the index of `VariantDef` given a constructor id.
2499 pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
2502 .find(|(_, v)| v.ctor_def_id == Some(cid))
2503 .expect("variant_index_with_ctor_id: unknown variant")
2507 pub fn variant_of_res(&self, res: Res) -> &VariantDef {
2509 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
2510 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
2511 Res::Def(DefKind::Struct, _)
2512 | Res::Def(DefKind::Union, _)
2513 | Res::Def(DefKind::TyAlias, _)
2514 | Res::Def(DefKind::AssocTy, _)
2516 | Res::SelfCtor(..) => self.non_enum_variant(),
2517 _ => bug!("unexpected res {:?} in variant_of_res", res),
2522 pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
2523 assert!(self.is_enum());
2524 let param_env = tcx.param_env(expr_did);
2525 let repr_type = self.repr.discr_type();
2526 match tcx.const_eval_poly(expr_did) {
2528 let ty = repr_type.to_ty(tcx);
2529 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
2530 trace!("discriminants: {} ({:?})", b, repr_type);
2531 Some(Discr { val: b, ty })
2533 info!("invalid enum discriminant: {:#?}", val);
2534 crate::mir::interpret::struct_error(
2535 tcx.at(tcx.def_span(expr_did)),
2536 "constant evaluation of enum discriminant resulted in non-integer",
2543 let msg = match err {
2544 ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => {
2545 "enum discriminant evaluation failed"
2547 ErrorHandled::TooGeneric => "enum discriminant depends on generics",
2549 tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg);
2556 pub fn discriminants(
2559 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
2560 assert!(self.is_enum());
2561 let repr_type = self.repr.discr_type();
2562 let initial = repr_type.initial_discriminant(tcx);
2563 let mut prev_discr = None::<Discr<'tcx>>;
2564 self.variants.iter_enumerated().map(move |(i, v)| {
2565 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
2566 if let VariantDiscr::Explicit(expr_did) = v.discr {
2567 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
2571 prev_discr = Some(discr);
2578 pub fn variant_range(&self) -> Range<VariantIdx> {
2579 VariantIdx::new(0)..VariantIdx::new(self.variants.len())
2582 /// Computes the discriminant value used by a specific variant.
2583 /// Unlike `discriminants`, this is (amortized) constant-time,
2584 /// only doing at most one query for evaluating an explicit
2585 /// discriminant (the last one before the requested variant),
2586 /// assuming there are no constant-evaluation errors there.
2588 pub fn discriminant_for_variant(
2591 variant_index: VariantIdx,
2593 assert!(self.is_enum());
2594 let (val, offset) = self.discriminant_def_for_variant(variant_index);
2595 let explicit_value = val
2596 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
2597 .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx));
2598 explicit_value.checked_add(tcx, offset as u128).0
2601 /// Yields a `DefId` for the discriminant and an offset to add to it
2602 /// Alternatively, if there is no explicit discriminant, returns the
2603 /// inferred discriminant directly.
2604 pub fn discriminant_def_for_variant(&self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
2605 assert!(!self.variants.is_empty());
2606 let mut explicit_index = variant_index.as_u32();
2609 match self.variants[VariantIdx::from_u32(explicit_index)].discr {
2610 ty::VariantDiscr::Relative(0) => {
2614 ty::VariantDiscr::Relative(distance) => {
2615 explicit_index -= distance;
2617 ty::VariantDiscr::Explicit(did) => {
2618 expr_did = Some(did);
2623 (expr_did, variant_index.as_u32() - explicit_index)
2626 pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
2627 tcx.adt_destructor(self.did)
2630 /// Returns a list of types such that `Self: Sized` if and only
2631 /// if that type is `Sized`, or `TyErr` if this type is recursive.
2633 /// Oddly enough, checking that the sized-constraint is `Sized` is
2634 /// actually more expressive than checking all members:
2635 /// the `Sized` trait is inductive, so an associated type that references
2636 /// `Self` would prevent its containing ADT from being `Sized`.
2638 /// Due to normalization being eager, this applies even if
2639 /// the associated type is behind a pointer (e.g., issue #31299).
2640 pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] {
2641 tcx.adt_sized_constraint(self.did).0
2645 impl<'tcx> FieldDef {
2646 /// Returns the type of this field. The `subst` is typically obtained
2647 /// via the second field of `TyKind::AdtDef`.
2648 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2649 tcx.type_of(self.did).subst(tcx, subst)
2653 /// Represents the various closure traits in the language. This
2654 /// will determine the type of the environment (`self`, in the
2655 /// desugaring) argument that the closure expects.
2657 /// You can get the environment type of a closure using
2658 /// `tcx.closure_env_ty()`.
2659 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
2660 #[derive(HashStable)]
2661 pub enum ClosureKind {
2662 // Warning: Ordering is significant here! The ordering is chosen
2663 // because the trait Fn is a subtrait of FnMut and so in turn, and
2664 // hence we order it so that Fn < FnMut < FnOnce.
2670 impl<'tcx> ClosureKind {
2671 // This is the initial value used when doing upvar inference.
2672 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2674 pub fn trait_did(&self, tcx: TyCtxt<'tcx>) -> DefId {
2676 ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem, None),
2677 ClosureKind::FnMut => tcx.require_lang_item(FnMutTraitLangItem, None),
2678 ClosureKind::FnOnce => tcx.require_lang_item(FnOnceTraitLangItem, None),
2682 /// Returns `true` if this a type that impls this closure kind
2683 /// must also implement `other`.
2684 pub fn extends(self, other: ty::ClosureKind) -> bool {
2685 match (self, other) {
2686 (ClosureKind::Fn, ClosureKind::Fn) => true,
2687 (ClosureKind::Fn, ClosureKind::FnMut) => true,
2688 (ClosureKind::Fn, ClosureKind::FnOnce) => true,
2689 (ClosureKind::FnMut, ClosureKind::FnMut) => true,
2690 (ClosureKind::FnMut, ClosureKind::FnOnce) => true,
2691 (ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
2696 /// Returns the representative scalar type for this closure kind.
2697 /// See `TyS::to_opt_closure_kind` for more details.
2698 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2700 ty::ClosureKind::Fn => tcx.types.i8,
2701 ty::ClosureKind::FnMut => tcx.types.i16,
2702 ty::ClosureKind::FnOnce => tcx.types.i32,
2708 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2710 hir::Mutability::Mut => MutBorrow,
2711 hir::Mutability::Not => ImmBorrow,
2715 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2716 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2717 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2719 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2721 MutBorrow => hir::Mutability::Mut,
2722 ImmBorrow => hir::Mutability::Not,
2724 // We have no type corresponding to a unique imm borrow, so
2725 // use `&mut`. It gives all the capabilities of an `&uniq`
2726 // and hence is a safe "over approximation".
2727 UniqueImmBorrow => hir::Mutability::Mut,
2731 pub fn to_user_str(&self) -> &'static str {
2733 MutBorrow => "mutable",
2734 ImmBorrow => "immutable",
2735 UniqueImmBorrow => "uniquely immutable",
2740 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
2742 #[derive(Debug, PartialEq, Eq)]
2743 pub enum ImplOverlapKind {
2744 /// These impls are always allowed to overlap.
2746 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
2749 /// These impls are allowed to overlap, but that raises
2750 /// an issue #33140 future-compatibility warning.
2752 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2753 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2755 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2756 /// that difference, making what reduces to the following set of impls:
2760 /// impl Trait for dyn Send + Sync {}
2761 /// impl Trait for dyn Sync + Send {}
2764 /// Obviously, once we made these types be identical, that code causes a coherence
2765 /// error and a fairly big headache for us. However, luckily for us, the trait
2766 /// `Trait` used in this case is basically a marker trait, and therefore having
2767 /// overlapping impls for it is sound.
2769 /// To handle this, we basically regard the trait as a marker trait, with an additional
2770 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2771 /// it has the following restrictions:
2773 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2775 /// 2. The trait-ref of both impls must be equal.
2776 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2778 /// 4. Neither of the impls can have any where-clauses.
2780 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2784 impl<'tcx> TyCtxt<'tcx> {
2785 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
2786 self.typeck(self.hir().body_owner_def_id(body))
2789 /// Returns an iterator of the `DefId`s for all body-owners in this
2790 /// crate. If you would prefer to iterate over the bodies
2791 /// themselves, you can do `self.hir().krate().body_ids.iter()`.
2792 pub fn body_owners(self) -> impl Iterator<Item = LocalDefId> + Captures<'tcx> + 'tcx {
2797 .map(move |&body_id| self.hir().body_owner_def_id(body_id))
2800 pub fn par_body_owners<F: Fn(LocalDefId) + sync::Sync + sync::Send>(self, f: F) {
2801 par_iter(&self.hir().krate().body_ids)
2802 .for_each(|&body_id| f(self.hir().body_owner_def_id(body_id)));
2805 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
2806 self.associated_items(id)
2807 .in_definition_order()
2808 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
2811 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
2814 .and_then(|def_id| self.hir().get(self.hir().as_local_hir_id(def_id)).ident())
2817 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2818 let is_associated_item = if let Some(def_id) = def_id.as_local() {
2819 match self.hir().get(self.hir().as_local_hir_id(def_id)) {
2820 Node::TraitItem(_) | Node::ImplItem(_) => true,
2824 match self.def_kind(def_id) {
2825 DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy => true,
2830 is_associated_item.then(|| self.associated_item(def_id))
2833 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
2834 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
2837 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2838 variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id))
2841 /// Returns `true` if the impls are the same polarity and the trait either
2842 /// has no items or is annotated `#[marker]` and prevents item overrides.
2843 pub fn impls_are_allowed_to_overlap(
2847 ) -> Option<ImplOverlapKind> {
2848 // If either trait impl references an error, they're allowed to overlap,
2849 // as one of them essentially doesn't exist.
2850 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2851 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2853 return Some(ImplOverlapKind::Permitted { marker: false });
2856 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2857 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2858 // `#[rustc_reservation_impl]` impls don't overlap with anything
2860 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2863 return Some(ImplOverlapKind::Permitted { marker: false });
2865 (ImplPolarity::Positive, ImplPolarity::Negative)
2866 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2867 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2869 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2874 (ImplPolarity::Positive, ImplPolarity::Positive)
2875 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2878 let is_marker_overlap = {
2879 let is_marker_impl = |def_id: DefId| -> bool {
2880 let trait_ref = self.impl_trait_ref(def_id);
2881 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2883 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2886 if is_marker_overlap {
2888 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2891 Some(ImplOverlapKind::Permitted { marker: true })
2893 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2894 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2895 if self_ty1 == self_ty2 {
2897 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2900 return Some(ImplOverlapKind::Issue33140);
2903 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2904 def_id1, def_id2, self_ty1, self_ty2
2910 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2915 /// Returns `ty::VariantDef` if `res` refers to a struct,
2916 /// or variant or their constructors, panics otherwise.
2917 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2919 Res::Def(DefKind::Variant, did) => {
2920 let enum_did = self.parent(did).unwrap();
2921 self.adt_def(enum_did).variant_with_id(did)
2923 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2924 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2925 let variant_did = self.parent(variant_ctor_did).unwrap();
2926 let enum_did = self.parent(variant_did).unwrap();
2927 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2929 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2930 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2931 self.adt_def(struct_did).non_enum_variant()
2933 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2937 pub fn item_name(self, id: DefId) -> Symbol {
2938 if id.index == CRATE_DEF_INDEX {
2939 self.original_crate_name(id.krate)
2941 let def_key = self.def_key(id);
2942 match def_key.disambiguated_data.data {
2943 // The name of a constructor is that of its parent.
2944 rustc_hir::definitions::DefPathData::Ctor => {
2945 self.item_name(DefId { krate: id.krate, index: def_key.parent.unwrap() })
2947 _ => def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
2948 bug!("item_name: no name for {:?}", self.def_path(id));
2954 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2955 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2957 ty::InstanceDef::Item(def) => {
2958 if let Some((did, param_did)) = def.as_const_arg() {
2959 self.optimized_mir_of_const_arg((did, param_did))
2961 self.optimized_mir(def.did)
2964 ty::InstanceDef::VtableShim(..)
2965 | ty::InstanceDef::ReifyShim(..)
2966 | ty::InstanceDef::Intrinsic(..)
2967 | ty::InstanceDef::FnPtrShim(..)
2968 | ty::InstanceDef::Virtual(..)
2969 | ty::InstanceDef::ClosureOnceShim { .. }
2970 | ty::InstanceDef::DropGlue(..)
2971 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2975 /// Gets the attributes of a definition.
2976 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
2977 if let Some(did) = did.as_local() {
2978 self.hir().attrs(self.hir().as_local_hir_id(did))
2980 self.item_attrs(did)
2984 /// Determines whether an item is annotated with an attribute.
2985 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2986 attr::contains_name(&self.get_attrs(did), attr)
2989 /// Returns `true` if this is an `auto trait`.
2990 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2991 self.trait_def(trait_def_id).has_auto_impl
2994 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
2995 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
2998 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2999 /// If it implements no trait, returns `None`.
3000 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
3001 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
3004 /// If the given defid describes a method belonging to an impl, returns the
3005 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
3006 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
3007 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
3008 TraitContainer(_) => None,
3009 ImplContainer(def_id) => Some(def_id),
3013 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
3014 /// with the name of the crate containing the impl.
3015 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
3016 if let Some(impl_did) = impl_did.as_local() {
3017 let hir_id = self.hir().as_local_hir_id(impl_did);
3018 Ok(self.hir().span(hir_id))
3020 Err(self.crate_name(impl_did.krate))
3024 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
3025 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
3026 /// definition's parent/scope to perform comparison.
3027 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
3028 // We could use `Ident::eq` here, but we deliberately don't. The name
3029 // comparison fails frequently, and we want to avoid the expensive
3030 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
3031 use_name.name == def_name.name
3035 .hygienic_eq(def_name.span.ctxt(), self.expansion_that_defined(def_parent_def_id))
3038 fn expansion_that_defined(self, scope: DefId) -> ExpnId {
3039 match scope.as_local() {
3040 Some(scope) => self.hir().definitions().expansion_that_defined(scope),
3041 None => ExpnId::root(),
3045 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
3046 ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope));
3050 pub fn adjust_ident_and_get_scope(
3055 ) -> (Ident, DefId) {
3057 match ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope))
3059 Some(actual_expansion) => {
3060 self.hir().definitions().parent_module_of_macro_def(actual_expansion)
3062 None => self.parent_module(block).to_def_id(),
3067 pub fn is_object_safe(self, key: DefId) -> bool {
3068 self.object_safety_violations(key).is_empty()
3072 #[derive(Clone, HashStable)]
3073 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
3075 /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition.
3076 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
3077 if let Some(def_id) = def_id.as_local() {
3078 if let Node::Item(item) = tcx.hir().get(tcx.hir().as_local_hir_id(def_id)) {
3079 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
3080 return opaque_ty.impl_trait_fn;
3087 pub fn provide(providers: &mut ty::query::Providers) {
3088 context::provide(providers);
3089 erase_regions::provide(providers);
3090 layout::provide(providers);
3091 super::util::bug::provide(providers);
3092 *providers = ty::query::Providers {
3093 trait_impls_of: trait_def::trait_impls_of_provider,
3094 all_local_trait_impls: trait_def::all_local_trait_impls,
3099 /// A map for the local crate mapping each type to a vector of its
3100 /// inherent impls. This is not meant to be used outside of coherence;
3101 /// rather, you should request the vector for a specific type via
3102 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
3103 /// (constructing this map requires touching the entire crate).
3104 #[derive(Clone, Debug, Default, HashStable)]
3105 pub struct CrateInherentImpls {
3106 pub inherent_impls: DefIdMap<Vec<DefId>>,
3109 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
3110 pub struct SymbolName<'tcx> {
3111 /// `&str` gives a consistent ordering, which ensures reproducible builds.
3112 pub name: &'tcx str,
3115 impl<'tcx> SymbolName<'tcx> {
3116 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
3118 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
3123 impl<'tcx> fmt::Display for SymbolName<'tcx> {
3124 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3125 fmt::Display::fmt(&self.name, fmt)
3129 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
3130 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3131 fmt::Display::fmt(&self.name, fmt)
3135 impl<'tcx> rustc_serialize::UseSpecializedEncodable for SymbolName<'tcx> {
3136 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
3137 s.emit_str(self.name)
3141 // The decoding takes place in `decode_symbol_name()`.
3142 impl<'tcx> rustc_serialize::UseSpecializedDecodable for SymbolName<'tcx> {}