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, Hash)]
140 pub enum AssocItemContainer {
141 TraitContainer(DefId),
142 ImplContainer(DefId),
145 impl AssocItemContainer {
146 /// Asserts that this is the `DefId` of an associated item declared
147 /// in a trait, and returns the trait `DefId`.
148 pub fn assert_trait(&self) -> DefId {
150 TraitContainer(id) => id,
151 _ => bug!("associated item has wrong container type: {:?}", self),
155 pub fn id(&self) -> DefId {
157 TraitContainer(id) => id,
158 ImplContainer(id) => id,
163 /// The "header" of an impl is everything outside the body: a Self type, a trait
164 /// ref (in the case of a trait impl), and a set of predicates (from the
165 /// bounds / where-clauses).
166 #[derive(Clone, Debug, TypeFoldable)]
167 pub struct ImplHeader<'tcx> {
168 pub impl_def_id: DefId,
169 pub self_ty: Ty<'tcx>,
170 pub trait_ref: Option<TraitRef<'tcx>>,
171 pub predicates: Vec<Predicate<'tcx>>,
174 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)]
175 pub enum ImplPolarity {
176 /// `impl Trait for Type`
178 /// `impl !Trait for Type`
180 /// `#[rustc_reservation_impl] impl Trait for Type`
182 /// This is a "stability hack", not a real Rust feature.
183 /// See #64631 for details.
187 #[derive(Copy, Clone, Debug, PartialEq, HashStable, Eq, Hash)]
188 pub struct AssocItem {
190 #[stable_hasher(project(name))]
194 pub defaultness: hir::Defaultness,
195 pub container: AssocItemContainer,
197 /// Whether this is a method with an explicit self
198 /// as its first parameter, allowing method calls.
199 pub fn_has_self_parameter: bool,
202 #[derive(Copy, Clone, PartialEq, Debug, HashStable, Eq, Hash)]
210 pub fn namespace(&self) -> Namespace {
212 ty::AssocKind::Type => Namespace::TypeNS,
213 ty::AssocKind::Const | ty::AssocKind::Fn => Namespace::ValueNS,
217 pub fn as_def_kind(&self) -> DefKind {
219 AssocKind::Const => DefKind::AssocConst,
220 AssocKind::Fn => DefKind::AssocFn,
221 AssocKind::Type => DefKind::AssocTy,
227 pub fn signature(&self, tcx: TyCtxt<'_>) -> String {
229 ty::AssocKind::Fn => {
230 // We skip the binder here because the binder would deanonymize all
231 // late-bound regions, and we don't want method signatures to show up
232 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
233 // regions just fine, showing `fn(&MyType)`.
234 tcx.fn_sig(self.def_id).skip_binder().to_string()
236 ty::AssocKind::Type => format!("type {};", self.ident),
237 ty::AssocKind::Const => {
238 format!("const {}: {:?};", self.ident, tcx.type_of(self.def_id))
244 /// A list of `ty::AssocItem`s in definition order that allows for efficient lookup by name.
246 /// When doing lookup by name, we try to postpone hygienic comparison for as long as possible since
247 /// it is relatively expensive. Instead, items are indexed by `Symbol` and hygienic comparison is
248 /// done only on items with the same name.
249 #[derive(Debug, Clone, PartialEq, HashStable)]
250 pub struct AssociatedItems<'tcx> {
251 items: SortedIndexMultiMap<u32, Symbol, &'tcx ty::AssocItem>,
254 impl<'tcx> AssociatedItems<'tcx> {
255 /// Constructs an `AssociatedItems` map from a series of `ty::AssocItem`s in definition order.
256 pub fn new(items_in_def_order: impl IntoIterator<Item = &'tcx ty::AssocItem>) -> Self {
257 let items = items_in_def_order.into_iter().map(|item| (item.ident.name, item)).collect();
258 AssociatedItems { items }
261 /// Returns a slice of associated items in the order they were defined.
263 /// New code should avoid relying on definition order. If you need a particular associated item
264 /// for a known trait, make that trait a lang item instead of indexing this array.
265 pub fn in_definition_order(&self) -> impl '_ + Iterator<Item = &ty::AssocItem> {
266 self.items.iter().map(|(_, v)| *v)
269 /// Returns an iterator over all associated items with the given name, ignoring hygiene.
270 pub fn filter_by_name_unhygienic(
273 ) -> impl '_ + Iterator<Item = &ty::AssocItem> {
274 self.items.get_by_key(&name).copied()
277 /// Returns an iterator over all associated items with the given name.
279 /// Multiple items may have the same name if they are in different `Namespace`s. For example,
280 /// an associated type can have the same name as a method. Use one of the `find_by_name_and_*`
281 /// methods below if you know which item you are looking for.
282 pub fn filter_by_name(
286 parent_def_id: DefId,
287 ) -> impl 'a + Iterator<Item = &'a ty::AssocItem> {
288 self.filter_by_name_unhygienic(ident.name)
289 .filter(move |item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
292 /// Returns the associated item with the given name and `AssocKind`, if one exists.
293 pub fn find_by_name_and_kind(
298 parent_def_id: DefId,
299 ) -> Option<&ty::AssocItem> {
300 self.filter_by_name_unhygienic(ident.name)
301 .filter(|item| item.kind == kind)
302 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
305 /// Returns the associated item with the given name in the given `Namespace`, if one exists.
306 pub fn find_by_name_and_namespace(
311 parent_def_id: DefId,
312 ) -> Option<&ty::AssocItem> {
313 self.filter_by_name_unhygienic(ident.name)
314 .filter(|item| item.kind.namespace() == ns)
315 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
319 #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable, HashStable, Hash)]
320 pub enum Visibility {
321 /// Visible everywhere (including in other crates).
323 /// Visible only in the given crate-local module.
325 /// Not visible anywhere in the local crate. This is the visibility of private external items.
329 pub trait DefIdTree: Copy {
330 fn parent(self, id: DefId) -> Option<DefId>;
332 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
333 if descendant.krate != ancestor.krate {
337 while descendant != ancestor {
338 match self.parent(descendant) {
339 Some(parent) => descendant = parent,
340 None => return false,
347 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
348 fn parent(self, id: DefId) -> Option<DefId> {
349 self.def_key(id).parent.map(|index| DefId { index, ..id })
354 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
355 match visibility.node {
356 hir::VisibilityKind::Public => Visibility::Public,
357 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
358 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
359 // If there is no resolution, `resolve` will have already reported an error, so
360 // assume that the visibility is public to avoid reporting more privacy errors.
361 Res::Err => Visibility::Public,
362 def => Visibility::Restricted(def.def_id()),
364 hir::VisibilityKind::Inherited => {
365 Visibility::Restricted(tcx.parent_module(id).to_def_id())
370 /// Returns `true` if an item with this visibility is accessible from the given block.
371 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
372 let restriction = match self {
373 // Public items are visible everywhere.
374 Visibility::Public => return true,
375 // Private items from other crates are visible nowhere.
376 Visibility::Invisible => return false,
377 // Restricted items are visible in an arbitrary local module.
378 Visibility::Restricted(other) if other.krate != module.krate => return false,
379 Visibility::Restricted(module) => module,
382 tree.is_descendant_of(module, restriction)
385 /// Returns `true` if this visibility is at least as accessible as the given visibility
386 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
387 let vis_restriction = match vis {
388 Visibility::Public => return self == Visibility::Public,
389 Visibility::Invisible => return true,
390 Visibility::Restricted(module) => module,
393 self.is_accessible_from(vis_restriction, tree)
396 // Returns `true` if this item is visible anywhere in the local crate.
397 pub fn is_visible_locally(self) -> bool {
399 Visibility::Public => true,
400 Visibility::Restricted(def_id) => def_id.is_local(),
401 Visibility::Invisible => false,
406 #[derive(Copy, Clone, PartialEq, RustcDecodable, RustcEncodable, HashStable)]
408 Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
409 Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
410 Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
411 Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
414 /// The crate variances map is computed during typeck and contains the
415 /// variance of every item in the local crate. You should not use it
416 /// directly, because to do so will make your pass dependent on the
417 /// HIR of every item in the local crate. Instead, use
418 /// `tcx.variances_of()` to get the variance for a *particular*
420 #[derive(HashStable)]
421 pub struct CrateVariancesMap<'tcx> {
422 /// For each item with generics, maps to a vector of the variance
423 /// of its generics. If an item has no generics, it will have no
425 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
429 /// `a.xform(b)` combines the variance of a context with the
430 /// variance of a type with the following meaning. If we are in a
431 /// context with variance `a`, and we encounter a type argument in
432 /// a position with variance `b`, then `a.xform(b)` is the new
433 /// variance with which the argument appears.
439 /// Here, the "ambient" variance starts as covariant. `*mut T` is
440 /// invariant with respect to `T`, so the variance in which the
441 /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which
442 /// yields `Invariant`. Now, the type `Vec<T>` is covariant with
443 /// respect to its type argument `T`, and hence the variance of
444 /// the `i32` here is `Invariant.xform(Covariant)`, which results
445 /// (again) in `Invariant`.
449 /// fn(*const Vec<i32>, *mut Vec<i32)
451 /// The ambient variance is covariant. A `fn` type is
452 /// contravariant with respect to its parameters, so the variance
453 /// within which both pointer types appear is
454 /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const
455 /// T` is covariant with respect to `T`, so the variance within
456 /// which the first `Vec<i32>` appears is
457 /// `Contravariant.xform(Covariant)` or `Contravariant`. The same
458 /// is true for its `i32` argument. In the `*mut T` case, the
459 /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`,
460 /// and hence the outermost type is `Invariant` with respect to
461 /// `Vec<i32>` (and its `i32` argument).
463 /// Source: Figure 1 of "Taming the Wildcards:
464 /// Combining Definition- and Use-Site Variance" published in PLDI'11.
465 pub fn xform(self, v: ty::Variance) -> ty::Variance {
467 // Figure 1, column 1.
468 (ty::Covariant, ty::Covariant) => ty::Covariant,
469 (ty::Covariant, ty::Contravariant) => ty::Contravariant,
470 (ty::Covariant, ty::Invariant) => ty::Invariant,
471 (ty::Covariant, ty::Bivariant) => ty::Bivariant,
473 // Figure 1, column 2.
474 (ty::Contravariant, ty::Covariant) => ty::Contravariant,
475 (ty::Contravariant, ty::Contravariant) => ty::Covariant,
476 (ty::Contravariant, ty::Invariant) => ty::Invariant,
477 (ty::Contravariant, ty::Bivariant) => ty::Bivariant,
479 // Figure 1, column 3.
480 (ty::Invariant, _) => ty::Invariant,
482 // Figure 1, column 4.
483 (ty::Bivariant, _) => ty::Bivariant,
488 // Contains information needed to resolve types and (in the future) look up
489 // the types of AST nodes.
490 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
491 pub struct CReaderCacheKey {
497 /// Flags that we track on types. These flags are propagated upwards
498 /// through the type during type construction, so that we can quickly check
499 /// whether the type has various kinds of types in it without recursing
500 /// over the type itself.
501 pub struct TypeFlags: u32 {
502 // Does this have parameters? Used to determine whether substitution is
504 /// Does this have [Param]?
505 const HAS_TY_PARAM = 1 << 0;
506 /// Does this have [ReEarlyBound]?
507 const HAS_RE_PARAM = 1 << 1;
508 /// Does this have [ConstKind::Param]?
509 const HAS_CT_PARAM = 1 << 2;
511 const NEEDS_SUBST = TypeFlags::HAS_TY_PARAM.bits
512 | TypeFlags::HAS_RE_PARAM.bits
513 | TypeFlags::HAS_CT_PARAM.bits;
515 /// Does this have [Infer]?
516 const HAS_TY_INFER = 1 << 3;
517 /// Does this have [ReVar]?
518 const HAS_RE_INFER = 1 << 4;
519 /// Does this have [ConstKind::Infer]?
520 const HAS_CT_INFER = 1 << 5;
522 /// Does this have inference variables? Used to determine whether
523 /// inference is required.
524 const NEEDS_INFER = TypeFlags::HAS_TY_INFER.bits
525 | TypeFlags::HAS_RE_INFER.bits
526 | TypeFlags::HAS_CT_INFER.bits;
528 /// Does this have [Placeholder]?
529 const HAS_TY_PLACEHOLDER = 1 << 6;
530 /// Does this have [RePlaceholder]?
531 const HAS_RE_PLACEHOLDER = 1 << 7;
532 /// Does this have [ConstKind::Placeholder]?
533 const HAS_CT_PLACEHOLDER = 1 << 8;
535 /// `true` if there are "names" of regions and so forth
536 /// that are local to a particular fn/inferctxt
537 const HAS_FREE_LOCAL_REGIONS = 1 << 9;
539 /// `true` if there are "names" of types and regions and so forth
540 /// that are local to a particular fn
541 const HAS_FREE_LOCAL_NAMES = TypeFlags::HAS_TY_PARAM.bits
542 | TypeFlags::HAS_CT_PARAM.bits
543 | TypeFlags::HAS_TY_INFER.bits
544 | TypeFlags::HAS_CT_INFER.bits
545 | TypeFlags::HAS_TY_PLACEHOLDER.bits
546 | TypeFlags::HAS_CT_PLACEHOLDER.bits
547 | TypeFlags::HAS_FREE_LOCAL_REGIONS.bits;
549 /// Does this have [Projection]?
550 const HAS_TY_PROJECTION = 1 << 10;
551 /// Does this have [Opaque]?
552 const HAS_TY_OPAQUE = 1 << 11;
553 /// Does this have [ConstKind::Unevaluated]?
554 const HAS_CT_PROJECTION = 1 << 12;
556 /// Could this type be normalized further?
557 const HAS_PROJECTION = TypeFlags::HAS_TY_PROJECTION.bits
558 | TypeFlags::HAS_TY_OPAQUE.bits
559 | TypeFlags::HAS_CT_PROJECTION.bits;
561 /// Is an error type/const reachable?
562 const HAS_ERROR = 1 << 13;
564 /// Does this have any region that "appears free" in the type?
565 /// Basically anything but [ReLateBound] and [ReErased].
566 const HAS_FREE_REGIONS = 1 << 14;
568 /// Does this have any [ReLateBound] regions? Used to check
569 /// if a global bound is safe to evaluate.
570 const HAS_RE_LATE_BOUND = 1 << 15;
572 /// Does this have any [ReErased] regions?
573 const HAS_RE_ERASED = 1 << 16;
575 /// Does this value have parameters/placeholders/inference variables which could be
576 /// replaced later, in a way that would change the results of `impl` specialization?
577 const STILL_FURTHER_SPECIALIZABLE = 1 << 17;
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 impl<'tcx> Predicate<'tcx> {
1069 pub fn kint(self, tcx: TyCtxt<'tcx>) -> &'tcx PredicateKint<'tcx> {
1071 tcx.intern_predicate_kint(match *self.kind() {
1072 PredicateKind::Trait(binder, data) => {
1073 if let Some(simpl) = binder.no_bound_vars() {
1074 PredicateKint::Trait(simpl, data)
1077 .intern_predicate_kint(PredicateKint::Trait(*binder.skip_binder(), data));
1078 PredicateKint::ForAll(Binder::bind(inner))
1081 PredicateKind::RegionOutlives(binder) => {
1082 if let Some(simpl) = binder.no_bound_vars() {
1083 PredicateKint::RegionOutlives(simpl)
1085 let inner = tcx.intern_predicate_kint(PredicateKint::RegionOutlives(
1086 *binder.skip_binder(),
1088 PredicateKint::ForAll(Binder::bind(inner))
1091 PredicateKind::TypeOutlives(binder) => {
1092 if let Some(simpl) = binder.no_bound_vars() {
1093 PredicateKint::TypeOutlives(simpl)
1096 .intern_predicate_kint(PredicateKint::TypeOutlives(*binder.skip_binder()));
1097 PredicateKint::ForAll(Binder::bind(inner))
1100 PredicateKind::Projection(binder) => {
1101 if let Some(simpl) = binder.no_bound_vars() {
1102 PredicateKint::Projection(simpl)
1105 tcx.intern_predicate_kint(PredicateKint::Projection(*binder.skip_binder()));
1106 PredicateKint::ForAll(Binder::bind(inner))
1109 PredicateKind::WellFormed(arg) => PredicateKint::WellFormed(arg),
1110 PredicateKind::ObjectSafe(def_id) => PredicateKint::ObjectSafe(def_id),
1111 PredicateKind::ClosureKind(def_id, substs, kind) => {
1112 PredicateKint::ClosureKind(def_id, substs, kind)
1114 PredicateKind::Subtype(binder) => {
1115 if let Some(simpl) = binder.no_bound_vars() {
1116 PredicateKint::Subtype(simpl)
1119 tcx.intern_predicate_kint(PredicateKint::Subtype(*binder.skip_binder()));
1120 PredicateKint::ForAll(Binder::bind(inner))
1123 PredicateKind::ConstEvaluatable(def, substs) => {
1124 PredicateKint::ConstEvaluatable(def, substs)
1126 PredicateKind::ConstEquate(l, r) => PredicateKint::ConstEquate(l, r),
1131 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
1132 #[derive(TypeFoldable)]
1133 pub enum PredicateKint<'tcx> {
1134 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
1135 /// the `Self` type of the trait reference and `A`, `B`, and `C`
1136 /// would be the type parameters.
1138 /// A trait predicate will have `Constness::Const` if it originates
1139 /// from a bound on a `const fn` without the `?const` opt-out (e.g.,
1140 /// `const fn foobar<Foo: Bar>() {}`).
1141 Trait(TraitPredicate<'tcx>, Constness),
1144 RegionOutlives(RegionOutlivesPredicate<'tcx>),
1147 TypeOutlives(TypeOutlivesPredicate<'tcx>),
1149 /// `where <T as TraitRef>::Name == X`, approximately.
1150 /// See the `ProjectionPredicate` struct for details.
1151 Projection(ProjectionPredicate<'tcx>),
1153 /// No syntax: `T` well-formed.
1154 WellFormed(GenericArg<'tcx>),
1156 /// Trait must be object-safe.
1159 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
1160 /// for some substitutions `...` and `T` being a closure type.
1161 /// Satisfied (or refuted) once we know the closure's kind.
1162 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
1165 Subtype(SubtypePredicate<'tcx>),
1167 /// Constant initializer must evaluate successfully.
1168 ConstEvaluatable(DefId, SubstsRef<'tcx>),
1170 /// Constants must be equal. The first component is the const that is expected.
1171 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
1174 ForAll(Binder<&'tcx PredicateKint<'tcx>>),
1177 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1178 #[derive(HashStable, TypeFoldable)]
1179 pub enum PredicateKind<'tcx> {
1180 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
1181 /// the `Self` type of the trait reference and `A`, `B`, and `C`
1182 /// would be the type parameters.
1184 /// A trait predicate will have `Constness::Const` if it originates
1185 /// from a bound on a `const fn` without the `?const` opt-out (e.g.,
1186 /// `const fn foobar<Foo: Bar>() {}`).
1187 Trait(PolyTraitPredicate<'tcx>, Constness),
1190 RegionOutlives(PolyRegionOutlivesPredicate<'tcx>),
1193 TypeOutlives(PolyTypeOutlivesPredicate<'tcx>),
1195 /// `where <T as TraitRef>::Name == X`, approximately.
1196 /// See the `ProjectionPredicate` struct for details.
1197 Projection(PolyProjectionPredicate<'tcx>),
1199 /// No syntax: `T` well-formed.
1200 WellFormed(GenericArg<'tcx>),
1202 /// Trait must be object-safe.
1205 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
1206 /// for some substitutions `...` and `T` being a closure type.
1207 /// Satisfied (or refuted) once we know the closure's kind.
1208 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
1211 Subtype(PolySubtypePredicate<'tcx>),
1213 /// Constant initializer must evaluate successfully.
1214 ConstEvaluatable(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>),
1216 /// Constants must be equal. The first component is the const that is expected.
1217 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
1220 /// The crate outlives map is computed during typeck and contains the
1221 /// outlives of every item in the local crate. You should not use it
1222 /// directly, because to do so will make your pass dependent on the
1223 /// HIR of every item in the local crate. Instead, use
1224 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
1226 #[derive(HashStable)]
1227 pub struct CratePredicatesMap<'tcx> {
1228 /// For each struct with outlive bounds, maps to a vector of the
1229 /// predicate of its outlive bounds. If an item has no outlives
1230 /// bounds, it will have no entry.
1231 pub predicates: FxHashMap<DefId, &'tcx [(ty::Predicate<'tcx>, Span)]>,
1234 impl<'tcx> Predicate<'tcx> {
1235 /// Performs a substitution suitable for going from a
1236 /// poly-trait-ref to supertraits that must hold if that
1237 /// poly-trait-ref holds. This is slightly different from a normal
1238 /// substitution in terms of what happens with bound regions. See
1239 /// lengthy comment below for details.
1240 pub fn subst_supertrait(
1243 trait_ref: &ty::PolyTraitRef<'tcx>,
1244 ) -> ty::Predicate<'tcx> {
1245 // The interaction between HRTB and supertraits is not entirely
1246 // obvious. Let me walk you (and myself) through an example.
1248 // Let's start with an easy case. Consider two traits:
1250 // trait Foo<'a>: Bar<'a,'a> { }
1251 // trait Bar<'b,'c> { }
1253 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
1254 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
1255 // knew that `Foo<'x>` (for any 'x) then we also know that
1256 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
1257 // normal substitution.
1259 // In terms of why this is sound, the idea is that whenever there
1260 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
1261 // holds. So if there is an impl of `T:Foo<'a>` that applies to
1262 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
1265 // Another example to be careful of is this:
1267 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
1268 // trait Bar1<'b,'c> { }
1270 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
1271 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
1272 // reason is similar to the previous example: any impl of
1273 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
1274 // basically we would want to collapse the bound lifetimes from
1275 // the input (`trait_ref`) and the supertraits.
1277 // To achieve this in practice is fairly straightforward. Let's
1278 // consider the more complicated scenario:
1280 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
1281 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
1282 // where both `'x` and `'b` would have a DB index of 1.
1283 // The substitution from the input trait-ref is therefore going to be
1284 // `'a => 'x` (where `'x` has a DB index of 1).
1285 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1286 // early-bound parameter and `'b' is a late-bound parameter with a
1288 // - If we replace `'a` with `'x` from the input, it too will have
1289 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1290 // just as we wanted.
1292 // There is only one catch. If we just apply the substitution `'a
1293 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1294 // adjust the DB index because we substituting into a binder (it
1295 // tries to be so smart...) resulting in `for<'x> for<'b>
1296 // Bar1<'x,'b>` (we have no syntax for this, so use your
1297 // imagination). Basically the 'x will have DB index of 2 and 'b
1298 // will have DB index of 1. Not quite what we want. So we apply
1299 // the substitution to the *contents* of the trait reference,
1300 // rather than the trait reference itself (put another way, the
1301 // substitution code expects equal binding levels in the values
1302 // from the substitution and the value being substituted into, and
1303 // this trick achieves that).
1305 let substs = trait_ref.skip_binder().substs;
1306 let kind = self.kind();
1307 let new = match kind {
1308 &PredicateKind::Trait(ref binder, constness) => {
1309 PredicateKind::Trait(binder.map_bound(|data| data.subst(tcx, substs)), constness)
1311 PredicateKind::Subtype(binder) => {
1312 PredicateKind::Subtype(binder.map_bound(|data| data.subst(tcx, substs)))
1314 PredicateKind::RegionOutlives(binder) => {
1315 PredicateKind::RegionOutlives(binder.map_bound(|data| data.subst(tcx, substs)))
1317 PredicateKind::TypeOutlives(binder) => {
1318 PredicateKind::TypeOutlives(binder.map_bound(|data| data.subst(tcx, substs)))
1320 PredicateKind::Projection(binder) => {
1321 PredicateKind::Projection(binder.map_bound(|data| data.subst(tcx, substs)))
1323 &PredicateKind::WellFormed(data) => PredicateKind::WellFormed(data.subst(tcx, substs)),
1324 &PredicateKind::ObjectSafe(trait_def_id) => PredicateKind::ObjectSafe(trait_def_id),
1325 &PredicateKind::ClosureKind(closure_def_id, closure_substs, kind) => {
1326 PredicateKind::ClosureKind(closure_def_id, closure_substs.subst(tcx, substs), kind)
1328 &PredicateKind::ConstEvaluatable(def_id, const_substs) => {
1329 PredicateKind::ConstEvaluatable(def_id, const_substs.subst(tcx, substs))
1331 PredicateKind::ConstEquate(c1, c2) => {
1332 PredicateKind::ConstEquate(c1.subst(tcx, substs), c2.subst(tcx, substs))
1336 if new != *kind { new.to_predicate(tcx) } else { self }
1340 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1341 #[derive(HashStable, TypeFoldable)]
1342 pub struct TraitPredicate<'tcx> {
1343 pub trait_ref: TraitRef<'tcx>,
1346 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1348 impl<'tcx> TraitPredicate<'tcx> {
1349 pub fn def_id(self) -> DefId {
1350 self.trait_ref.def_id
1353 pub fn self_ty(self) -> Ty<'tcx> {
1354 self.trait_ref.self_ty()
1358 impl<'tcx> PolyTraitPredicate<'tcx> {
1359 pub fn def_id(self) -> DefId {
1360 // Ok to skip binder since trait `DefId` does not care about regions.
1361 self.skip_binder().def_id()
1365 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1366 #[derive(HashStable, TypeFoldable)]
1367 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
1368 pub type PolyOutlivesPredicate<A, B> = ty::Binder<OutlivesPredicate<A, B>>;
1369 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
1370 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1371 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>;
1372 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>;
1374 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1375 #[derive(HashStable, TypeFoldable)]
1376 pub struct SubtypePredicate<'tcx> {
1377 pub a_is_expected: bool,
1381 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1383 /// This kind of predicate has no *direct* correspondent in the
1384 /// syntax, but it roughly corresponds to the syntactic forms:
1386 /// 1. `T: TraitRef<..., Item = Type>`
1387 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1389 /// In particular, form #1 is "desugared" to the combination of a
1390 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1391 /// predicates. Form #2 is a broader form in that it also permits
1392 /// equality between arbitrary types. Processing an instance of
1393 /// Form #2 eventually yields one of these `ProjectionPredicate`
1394 /// instances to normalize the LHS.
1395 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1396 #[derive(HashStable, TypeFoldable)]
1397 pub struct ProjectionPredicate<'tcx> {
1398 pub projection_ty: ProjectionTy<'tcx>,
1402 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1404 impl<'tcx> PolyProjectionPredicate<'tcx> {
1405 /// Returns the `DefId` of the associated item being projected.
1406 pub fn item_def_id(&self) -> DefId {
1407 self.skip_binder().projection_ty.item_def_id
1411 pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
1412 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1413 // `self.0.trait_ref` is permitted to have escaping regions.
1414 // This is because here `self` has a `Binder` and so does our
1415 // return value, so we are preserving the number of binding
1417 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1420 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1421 self.map_bound(|predicate| predicate.ty)
1424 /// The `DefId` of the `TraitItem` for the associated type.
1426 /// Note that this is not the `DefId` of the `TraitRef` containing this
1427 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1428 pub fn projection_def_id(&self) -> DefId {
1429 // Ok to skip binder since trait `DefId` does not care about regions.
1430 self.skip_binder().projection_ty.item_def_id
1434 pub trait ToPolyTraitRef<'tcx> {
1435 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1438 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1439 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1440 ty::Binder::dummy(*self)
1444 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1445 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1446 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1450 pub trait ToPredicate<'tcx> {
1451 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
1454 impl ToPredicate<'tcx> for PredicateKind<'tcx> {
1456 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1457 tcx.mk_predicate(self)
1461 impl ToPredicate<'tcx> for PredicateKint<'tcx> {
1463 fn to_predicate(&self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1464 let (predicate, in_binder) = if let PredicateKint::ForAll(binder) = self {
1465 (*binder.skip_binder(), true)
1485 PredicateKint::ForAll(_) => bug!("unexpected PredicateKint: {:?}", self),
1486 PredicateKint::Trait(data, ct) => PredicateKind::Trait(bind!(data), ct),
1487 PredicateKint::RegionOutlives(data) => PredicateKind::RegionOutlives(bind!(data)),
1488 PredicateKint::TypeOutlives(data) => PredicateKind::TypeOutlives(bind!(data)),
1489 PredicateKint::Projection(data) => PredicateKind::Projection(bind!(data)),
1490 PredicateKint::WellFormed(arg) => {
1492 bug!("unexpected ForAll: {:?}", self)
1494 PredicateKind::WellFormed(arg)
1497 PredicateKint::ObjectSafe(def_id) => {
1499 bug!("unexpected ForAll: {:?}", self)
1501 PredicateKind::ObjectSafe(def_id)
1504 PredicateKint::ClosureKind(def_id, substs, kind) => {
1506 bug!("unexpected ForAll: {:?}", self)
1508 PredicateKind::ClosureKind(def_id, substs, kind)
1511 PredicateKint::Subtype(data) => PredicateKind::Subtype(bind!(data)),
1512 PredicateKint::ConstEvaluatable(def_id, substs) => {
1514 bug!("unexpected ForAll: {:?}", self)
1516 PredicateKind::ConstEvaluatable(def_id, substs)
1519 PredicateKint::ConstEquate(l, r) => {
1521 bug!("unexpected ForAll: {:?}", self)
1523 PredicateKind::ConstEquate(l, r)
1531 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<TraitRef<'tcx>> {
1532 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1533 ty::PredicateKind::Trait(
1534 ty::Binder::dummy(ty::TraitPredicate { trait_ref: self.value }),
1541 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<&TraitRef<'tcx>> {
1542 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1543 ty::PredicateKind::Trait(
1544 ty::Binder::dummy(ty::TraitPredicate { trait_ref: *self.value }),
1551 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> {
1552 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1553 ty::PredicateKind::Trait(self.value.to_poly_trait_predicate(), self.constness)
1558 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1559 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1560 PredicateKind::RegionOutlives(self).to_predicate(tcx)
1564 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1565 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1566 PredicateKind::TypeOutlives(self).to_predicate(tcx)
1570 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1571 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1572 PredicateKind::Projection(self).to_predicate(tcx)
1576 impl<'tcx> Predicate<'tcx> {
1577 pub fn to_opt_poly_trait_ref(self) -> Option<PolyTraitRef<'tcx>> {
1579 &PredicateKind::Trait(ref t, _) => Some(t.to_poly_trait_ref()),
1580 PredicateKind::Projection(..)
1581 | PredicateKind::Subtype(..)
1582 | PredicateKind::RegionOutlives(..)
1583 | PredicateKind::WellFormed(..)
1584 | PredicateKind::ObjectSafe(..)
1585 | PredicateKind::ClosureKind(..)
1586 | PredicateKind::TypeOutlives(..)
1587 | PredicateKind::ConstEvaluatable(..)
1588 | PredicateKind::ConstEquate(..) => None,
1592 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1594 &PredicateKind::TypeOutlives(data) => Some(data),
1595 PredicateKind::Trait(..)
1596 | PredicateKind::Projection(..)
1597 | PredicateKind::Subtype(..)
1598 | PredicateKind::RegionOutlives(..)
1599 | PredicateKind::WellFormed(..)
1600 | PredicateKind::ObjectSafe(..)
1601 | PredicateKind::ClosureKind(..)
1602 | PredicateKind::ConstEvaluatable(..)
1603 | PredicateKind::ConstEquate(..) => None,
1608 /// Represents the bounds declared on a particular set of type
1609 /// parameters. Should eventually be generalized into a flag list of
1610 /// where-clauses. You can obtain a `InstantiatedPredicates` list from a
1611 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1612 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1613 /// the `GenericPredicates` are expressed in terms of the bound type
1614 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1615 /// represented a set of bounds for some particular instantiation,
1616 /// meaning that the generic parameters have been substituted with
1621 /// struct Foo<T, U: Bar<T>> { ... }
1623 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1624 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1625 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1626 /// [usize:Bar<isize>]]`.
1627 #[derive(Clone, Debug, TypeFoldable)]
1628 pub struct InstantiatedPredicates<'tcx> {
1629 pub predicates: Vec<Predicate<'tcx>>,
1630 pub spans: Vec<Span>,
1633 impl<'tcx> InstantiatedPredicates<'tcx> {
1634 pub fn empty() -> InstantiatedPredicates<'tcx> {
1635 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1638 pub fn is_empty(&self) -> bool {
1639 self.predicates.is_empty()
1643 rustc_index::newtype_index! {
1644 /// "Universes" are used during type- and trait-checking in the
1645 /// presence of `for<..>` binders to control what sets of names are
1646 /// visible. Universes are arranged into a tree: the root universe
1647 /// contains names that are always visible. Each child then adds a new
1648 /// set of names that are visible, in addition to those of its parent.
1649 /// We say that the child universe "extends" the parent universe with
1652 /// To make this more concrete, consider this program:
1656 /// fn bar<T>(x: T) {
1657 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1661 /// The struct name `Foo` is in the root universe U0. But the type
1662 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1663 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1664 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1665 /// region `'a` is in a universe U2 that extends U1, because we can
1666 /// name it inside the fn type but not outside.
1668 /// Universes are used to do type- and trait-checking around these
1669 /// "forall" binders (also called **universal quantification**). The
1670 /// idea is that when, in the body of `bar`, we refer to `T` as a
1671 /// type, we aren't referring to any type in particular, but rather a
1672 /// kind of "fresh" type that is distinct from all other types we have
1673 /// actually declared. This is called a **placeholder** type, and we
1674 /// use universes to talk about this. In other words, a type name in
1675 /// universe 0 always corresponds to some "ground" type that the user
1676 /// declared, but a type name in a non-zero universe is a placeholder
1677 /// type -- an idealized representative of "types in general" that we
1678 /// use for checking generic functions.
1679 pub struct UniverseIndex {
1681 DEBUG_FORMAT = "U{}",
1685 impl UniverseIndex {
1686 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1688 /// Returns the "next" universe index in order -- this new index
1689 /// is considered to extend all previous universes. This
1690 /// corresponds to entering a `forall` quantifier. So, for
1691 /// example, suppose we have this type in universe `U`:
1694 /// for<'a> fn(&'a u32)
1697 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1698 /// new universe that extends `U` -- in this new universe, we can
1699 /// name the region `'a`, but that region was not nameable from
1700 /// `U` because it was not in scope there.
1701 pub fn next_universe(self) -> UniverseIndex {
1702 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1705 /// Returns `true` if `self` can name a name from `other` -- in other words,
1706 /// if the set of names in `self` is a superset of those in
1707 /// `other` (`self >= other`).
1708 pub fn can_name(self, other: UniverseIndex) -> bool {
1709 self.private >= other.private
1712 /// Returns `true` if `self` cannot name some names from `other` -- in other
1713 /// words, if the set of names in `self` is a strict subset of
1714 /// those in `other` (`self < other`).
1715 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1716 self.private < other.private
1720 /// The "placeholder index" fully defines a placeholder region.
1721 /// Placeholder regions are identified by both a **universe** as well
1722 /// as a "bound-region" within that universe. The `bound_region` is
1723 /// basically a name -- distinct bound regions within the same
1724 /// universe are just two regions with an unknown relationship to one
1726 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1727 pub struct Placeholder<T> {
1728 pub universe: UniverseIndex,
1732 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1734 T: HashStable<StableHashingContext<'a>>,
1736 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1737 self.universe.hash_stable(hcx, hasher);
1738 self.name.hash_stable(hcx, hasher);
1742 pub type PlaceholderRegion = Placeholder<BoundRegion>;
1744 pub type PlaceholderType = Placeholder<BoundVar>;
1746 pub type PlaceholderConst = Placeholder<BoundVar>;
1748 /// A `DefId` which is potentially bundled with its corresponding generic parameter
1749 /// in case `did` is a const argument.
1751 /// This is used to prevent cycle errors during typeck
1752 /// as `type_of(const_arg)` depends on `typeck(owning_body)`
1753 /// which once again requires the type of its generic arguments.
1755 /// Luckily we only need to deal with const arguments once we
1756 /// know their corresponding parameters. We (ab)use this by
1757 /// calling `type_of(param_did)` for these arguments.
1760 /// #![feature(const_generics)]
1764 /// fn foo<const N: usize>(&self) -> usize { N }
1768 /// fn foo<const N: u8>(&self) -> usize { 42 }
1776 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, RustcEncodable, RustcDecodable)]
1777 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1778 #[derive(Hash, HashStable)]
1779 pub struct WithOptConstParam<T> {
1781 /// The `DefId` of the corresponding generic paramter in case `did` is
1782 /// a const argument.
1784 /// Note that even if `did` is a const argument, this may still be `None`.
1785 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1786 /// to potentially update `param_did` in case it `None`.
1787 pub const_param_did: Option<DefId>,
1790 impl<T> WithOptConstParam<T> {
1791 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1793 pub fn unknown(did: T) -> WithOptConstParam<T> {
1794 WithOptConstParam { did, const_param_did: None }
1798 impl WithOptConstParam<LocalDefId> {
1799 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1800 /// `None` otherwise.
1802 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1803 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1806 /// In case `self` is unknown but `self.did` is a const argument, this returns
1807 /// a `WithOptConstParam` with the correct `const_param_did`.
1809 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1810 if self.const_param_did.is_none() {
1811 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1812 return Some(WithOptConstParam { did: self.did, const_param_did });
1819 pub fn to_global(self) -> WithOptConstParam<DefId> {
1820 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1823 pub fn def_id_for_type_of(self) -> DefId {
1824 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1828 impl WithOptConstParam<DefId> {
1829 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1832 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1835 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1836 if let Some(param_did) = self.const_param_did {
1837 if let Some(did) = self.did.as_local() {
1838 return Some((did, param_did));
1845 pub fn expect_local(self) -> WithOptConstParam<LocalDefId> {
1846 self.as_local().unwrap()
1849 pub fn is_local(self) -> bool {
1853 pub fn def_id_for_type_of(self) -> DefId {
1854 self.const_param_did.unwrap_or(self.did)
1858 /// When type checking, we use the `ParamEnv` to track
1859 /// details about the set of where-clauses that are in scope at this
1860 /// particular point.
1861 #[derive(Copy, Clone)]
1862 pub struct ParamEnv<'tcx> {
1863 // We pack the caller_bounds List pointer and a Reveal enum into this usize.
1864 // Specifically, the low bit represents Reveal, with 0 meaning `UserFacing`
1865 // and 1 meaning `All`. The rest is the pointer.
1867 // This relies on the List<ty::Predicate<'tcx>> type having at least 2-byte
1868 // alignment. Lists start with a usize and are repr(C) so this should be
1869 // fine; there is a debug_assert in the constructor as well.
1871 // Note that the choice of 0 for UserFacing is intentional -- since it is the
1872 // first variant in Reveal this means that joining the pointer is a simple `or`.
1875 /// `Obligation`s that the caller must satisfy. This is basically
1876 /// the set of bounds on the in-scope type parameters, translated
1877 /// into `Obligation`s, and elaborated and normalized.
1879 /// Note: This is packed into the `packed_data` usize above, use the
1880 /// `caller_bounds()` method to access it.
1881 caller_bounds: PhantomData<&'tcx List<ty::Predicate<'tcx>>>,
1883 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1884 /// want `Reveal::All`.
1886 /// Note: This is packed into the caller_bounds usize above, use the reveal()
1887 /// method to access it.
1888 reveal: PhantomData<traits::Reveal>,
1890 /// If this `ParamEnv` comes from a call to `tcx.param_env(def_id)`,
1891 /// register that `def_id` (useful for transitioning to the chalk trait
1893 pub def_id: Option<DefId>,
1896 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1897 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1898 f.debug_struct("ParamEnv")
1899 .field("caller_bounds", &self.caller_bounds())
1900 .field("reveal", &self.reveal())
1901 .field("def_id", &self.def_id)
1906 impl<'tcx> Hash for ParamEnv<'tcx> {
1907 fn hash<H: Hasher>(&self, state: &mut H) {
1908 // List hashes as the raw pointer, so we can skip splitting into the
1909 // pointer and the enum.
1910 self.packed_data.hash(state);
1911 self.def_id.hash(state);
1915 impl<'tcx> PartialEq for ParamEnv<'tcx> {
1916 fn eq(&self, other: &Self) -> bool {
1917 self.caller_bounds() == other.caller_bounds()
1918 && self.reveal() == other.reveal()
1919 && self.def_id == other.def_id
1922 impl<'tcx> Eq for ParamEnv<'tcx> {}
1924 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1925 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1926 self.caller_bounds().hash_stable(hcx, hasher);
1927 self.reveal().hash_stable(hcx, hasher);
1928 self.def_id.hash_stable(hcx, hasher);
1932 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1933 fn super_fold_with<F: ty::fold::TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
1935 self.caller_bounds().fold_with(folder),
1936 self.reveal().fold_with(folder),
1937 self.def_id.fold_with(folder),
1941 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
1942 self.caller_bounds().visit_with(visitor)
1943 || self.reveal().visit_with(visitor)
1944 || self.def_id.visit_with(visitor)
1948 impl<'tcx> ParamEnv<'tcx> {
1949 /// Construct a trait environment suitable for contexts where
1950 /// there are no where-clauses in scope. Hidden types (like `impl
1951 /// Trait`) are left hidden, so this is suitable for ordinary
1954 pub fn empty() -> Self {
1955 Self::new(List::empty(), Reveal::UserFacing, None)
1959 pub fn caller_bounds(self) -> &'tcx List<ty::Predicate<'tcx>> {
1960 // mask out bottom bit
1961 unsafe { &*((self.packed_data & (!1)) as *const _) }
1965 pub fn reveal(self) -> traits::Reveal {
1966 if self.packed_data & 1 == 0 { traits::Reveal::UserFacing } else { traits::Reveal::All }
1969 /// Construct a trait environment with no where-clauses in scope
1970 /// where the values of all `impl Trait` and other hidden types
1971 /// are revealed. This is suitable for monomorphized, post-typeck
1972 /// environments like codegen or doing optimizations.
1974 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1975 /// or invoke `param_env.with_reveal_all()`.
1977 pub fn reveal_all() -> Self {
1978 Self::new(List::empty(), Reveal::All, None)
1981 /// Construct a trait environment with the given set of predicates.
1984 caller_bounds: &'tcx List<ty::Predicate<'tcx>>,
1986 def_id: Option<DefId>,
1988 let packed_data = caller_bounds as *const _ as usize;
1989 // Check that we can pack the reveal data into the pointer.
1990 debug_assert!(packed_data & 1 == 0);
1992 packed_data: packed_data
1994 Reveal::UserFacing => 0,
1997 caller_bounds: PhantomData,
1998 reveal: PhantomData,
2003 pub fn with_user_facing(mut self) -> Self {
2005 self.packed_data &= !1;
2009 /// Returns a new parameter environment with the same clauses, but
2010 /// which "reveals" the true results of projections in all cases
2011 /// (even for associated types that are specializable). This is
2012 /// the desired behavior during codegen and certain other special
2013 /// contexts; normally though we want to use `Reveal::UserFacing`,
2014 /// which is the default.
2015 pub fn with_reveal_all(mut self) -> Self {
2016 self.packed_data |= 1;
2020 /// Returns this same environment but with no caller bounds.
2021 pub fn without_caller_bounds(self) -> Self {
2022 Self::new(List::empty(), self.reveal(), self.def_id)
2025 /// Creates a suitable environment in which to perform trait
2026 /// queries on the given value. When type-checking, this is simply
2027 /// the pair of the environment plus value. But when reveal is set to
2028 /// All, then if `value` does not reference any type parameters, we will
2029 /// pair it with the empty environment. This improves caching and is generally
2032 /// N.B., we preserve the environment when type-checking because it
2033 /// is possible for the user to have wacky where-clauses like
2034 /// `where Box<u32>: Copy`, which are clearly never
2035 /// satisfiable. We generally want to behave as if they were true,
2036 /// although the surrounding function is never reachable.
2037 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
2038 match self.reveal() {
2039 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
2042 if value.is_global() {
2043 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
2045 ParamEnvAnd { param_env: self, value }
2052 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
2053 pub struct ConstnessAnd<T> {
2054 pub constness: Constness,
2058 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
2059 // the constness of trait bounds is being propagated correctly.
2060 pub trait WithConstness: Sized {
2062 fn with_constness(self, constness: Constness) -> ConstnessAnd<Self> {
2063 ConstnessAnd { constness, value: self }
2067 fn with_const(self) -> ConstnessAnd<Self> {
2068 self.with_constness(Constness::Const)
2072 fn without_const(self) -> ConstnessAnd<Self> {
2073 self.with_constness(Constness::NotConst)
2077 impl<T> WithConstness for T {}
2079 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
2080 pub struct ParamEnvAnd<'tcx, T> {
2081 pub param_env: ParamEnv<'tcx>,
2085 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
2086 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
2087 (self.param_env, self.value)
2091 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
2093 T: HashStable<StableHashingContext<'a>>,
2095 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
2096 let ParamEnvAnd { ref param_env, ref value } = *self;
2098 param_env.hash_stable(hcx, hasher);
2099 value.hash_stable(hcx, hasher);
2103 #[derive(Copy, Clone, Debug, HashStable)]
2104 pub struct Destructor {
2105 /// The `DefId` of the destructor method
2110 #[derive(HashStable)]
2111 pub struct AdtFlags: u32 {
2112 const NO_ADT_FLAGS = 0;
2113 /// Indicates whether the ADT is an enum.
2114 const IS_ENUM = 1 << 0;
2115 /// Indicates whether the ADT is a union.
2116 const IS_UNION = 1 << 1;
2117 /// Indicates whether the ADT is a struct.
2118 const IS_STRUCT = 1 << 2;
2119 /// Indicates whether the ADT is a struct and has a constructor.
2120 const HAS_CTOR = 1 << 3;
2121 /// Indicates whether the type is `PhantomData`.
2122 const IS_PHANTOM_DATA = 1 << 4;
2123 /// Indicates whether the type has a `#[fundamental]` attribute.
2124 const IS_FUNDAMENTAL = 1 << 5;
2125 /// Indicates whether the type is `Box`.
2126 const IS_BOX = 1 << 6;
2127 /// Indicates whether the type is `ManuallyDrop`.
2128 const IS_MANUALLY_DROP = 1 << 7;
2129 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
2130 /// (i.e., this flag is never set unless this ADT is an enum).
2131 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
2136 #[derive(HashStable)]
2137 pub struct VariantFlags: u32 {
2138 const NO_VARIANT_FLAGS = 0;
2139 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
2140 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
2144 /// Definition of a variant -- a struct's fields or a enum variant.
2145 #[derive(Debug, HashStable)]
2146 pub struct VariantDef {
2147 /// `DefId` that identifies the variant itself.
2148 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
2150 /// `DefId` that identifies the variant's constructor.
2151 /// If this variant is a struct variant, then this is `None`.
2152 pub ctor_def_id: Option<DefId>,
2153 /// Variant or struct name.
2154 #[stable_hasher(project(name))]
2156 /// Discriminant of this variant.
2157 pub discr: VariantDiscr,
2158 /// Fields of this variant.
2159 pub fields: Vec<FieldDef>,
2160 /// Type of constructor of variant.
2161 pub ctor_kind: CtorKind,
2162 /// Flags of the variant (e.g. is field list non-exhaustive)?
2163 flags: VariantFlags,
2164 /// Variant is obtained as part of recovering from a syntactic error.
2165 /// May be incomplete or bogus.
2166 pub recovered: bool,
2169 impl<'tcx> VariantDef {
2170 /// Creates a new `VariantDef`.
2172 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
2173 /// represents an enum variant).
2175 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
2176 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
2178 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
2179 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
2180 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
2181 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
2182 /// built-in trait), and we do not want to load attributes twice.
2184 /// If someone speeds up attribute loading to not be a performance concern, they can
2185 /// remove this hack and use the constructor `DefId` everywhere.
2189 variant_did: Option<DefId>,
2190 ctor_def_id: Option<DefId>,
2191 discr: VariantDiscr,
2192 fields: Vec<FieldDef>,
2193 ctor_kind: CtorKind,
2199 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
2200 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
2201 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
2204 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
2205 if adt_kind == AdtKind::Struct && tcx.has_attr(parent_did, sym::non_exhaustive) {
2206 debug!("found non-exhaustive field list for {:?}", parent_did);
2207 flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
2208 } else if let Some(variant_did) = variant_did {
2209 if tcx.has_attr(variant_did, sym::non_exhaustive) {
2210 debug!("found non-exhaustive field list for {:?}", variant_did);
2211 flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
2216 def_id: variant_did.unwrap_or(parent_did),
2227 /// Is this field list non-exhaustive?
2229 pub fn is_field_list_non_exhaustive(&self) -> bool {
2230 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
2233 /// `repr(transparent)` structs can have a single non-ZST field, this function returns that
2235 pub fn transparent_newtype_field(&self, tcx: TyCtxt<'tcx>) -> Option<&FieldDef> {
2236 for field in &self.fields {
2237 let field_ty = field.ty(tcx, InternalSubsts::identity_for_item(tcx, self.def_id));
2238 if !field_ty.is_zst(tcx, self.def_id) {
2247 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
2248 pub enum VariantDiscr {
2249 /// Explicit value for this variant, i.e., `X = 123`.
2250 /// The `DefId` corresponds to the embedded constant.
2253 /// The previous variant's discriminant plus one.
2254 /// For efficiency reasons, the distance from the
2255 /// last `Explicit` discriminant is being stored,
2256 /// or `0` for the first variant, if it has none.
2260 #[derive(Debug, HashStable)]
2261 pub struct FieldDef {
2263 #[stable_hasher(project(name))]
2265 pub vis: Visibility,
2268 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
2270 /// These are all interned (by `alloc_adt_def`) into the global arena.
2272 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
2273 /// This is slightly wrong because `union`s are not ADTs.
2274 /// Moreover, Rust only allows recursive data types through indirection.
2276 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
2278 /// The `DefId` of the struct, enum or union item.
2280 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
2281 pub variants: IndexVec<VariantIdx, VariantDef>,
2282 /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
2284 /// Repr options provided by the user.
2285 pub repr: ReprOptions,
2288 impl PartialOrd for AdtDef {
2289 fn partial_cmp(&self, other: &AdtDef) -> Option<Ordering> {
2290 Some(self.cmp(&other))
2294 /// There should be only one AdtDef for each `did`, therefore
2295 /// it is fine to implement `Ord` only based on `did`.
2296 impl Ord for AdtDef {
2297 fn cmp(&self, other: &AdtDef) -> Ordering {
2298 self.did.cmp(&other.did)
2302 impl PartialEq for AdtDef {
2303 // `AdtDef`s are always interned, and this is part of `TyS` equality.
2305 fn eq(&self, other: &Self) -> bool {
2306 ptr::eq(self, other)
2310 impl Eq for AdtDef {}
2312 impl Hash for AdtDef {
2314 fn hash<H: Hasher>(&self, s: &mut H) {
2315 (self as *const AdtDef).hash(s)
2319 impl<'tcx> rustc_serialize::UseSpecializedEncodable for &'tcx AdtDef {
2320 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
2325 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx AdtDef {}
2327 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
2328 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
2330 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default();
2333 let hash: Fingerprint = CACHE.with(|cache| {
2334 let addr = self as *const AdtDef as usize;
2335 *cache.borrow_mut().entry(addr).or_insert_with(|| {
2336 let ty::AdtDef { did, ref variants, ref flags, ref repr } = *self;
2338 let mut hasher = StableHasher::new();
2339 did.hash_stable(hcx, &mut hasher);
2340 variants.hash_stable(hcx, &mut hasher);
2341 flags.hash_stable(hcx, &mut hasher);
2342 repr.hash_stable(hcx, &mut hasher);
2348 hash.hash_stable(hcx, hasher);
2352 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
2359 impl Into<DataTypeKind> for AdtKind {
2360 fn into(self) -> DataTypeKind {
2362 AdtKind::Struct => DataTypeKind::Struct,
2363 AdtKind::Union => DataTypeKind::Union,
2364 AdtKind::Enum => DataTypeKind::Enum,
2370 #[derive(RustcEncodable, RustcDecodable, Default, HashStable)]
2371 pub struct ReprFlags: u8 {
2372 const IS_C = 1 << 0;
2373 const IS_SIMD = 1 << 1;
2374 const IS_TRANSPARENT = 1 << 2;
2375 // Internal only for now. If true, don't reorder fields.
2376 const IS_LINEAR = 1 << 3;
2377 // If true, don't expose any niche to type's context.
2378 const HIDE_NICHE = 1 << 4;
2379 // Any of these flags being set prevent field reordering optimisation.
2380 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
2381 ReprFlags::IS_SIMD.bits |
2382 ReprFlags::IS_LINEAR.bits;
2386 /// Represents the repr options provided by the user,
2387 #[derive(Copy, Clone, Debug, Eq, PartialEq, RustcEncodable, RustcDecodable, Default, HashStable)]
2388 pub struct ReprOptions {
2389 pub int: Option<attr::IntType>,
2390 pub align: Option<Align>,
2391 pub pack: Option<Align>,
2392 pub flags: ReprFlags,
2396 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
2397 let mut flags = ReprFlags::empty();
2398 let mut size = None;
2399 let mut max_align: Option<Align> = None;
2400 let mut min_pack: Option<Align> = None;
2401 for attr in tcx.get_attrs(did).iter() {
2402 for r in attr::find_repr_attrs(&tcx.sess.parse_sess, attr) {
2403 flags.insert(match r {
2404 attr::ReprC => ReprFlags::IS_C,
2405 attr::ReprPacked(pack) => {
2406 let pack = Align::from_bytes(pack as u64).unwrap();
2407 min_pack = Some(if let Some(min_pack) = min_pack {
2414 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2415 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
2416 attr::ReprSimd => ReprFlags::IS_SIMD,
2417 attr::ReprInt(i) => {
2421 attr::ReprAlign(align) => {
2422 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2429 // This is here instead of layout because the choice must make it into metadata.
2430 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2431 flags.insert(ReprFlags::IS_LINEAR);
2433 ReprOptions { int: size, align: max_align, pack: min_pack, flags }
2437 pub fn simd(&self) -> bool {
2438 self.flags.contains(ReprFlags::IS_SIMD)
2441 pub fn c(&self) -> bool {
2442 self.flags.contains(ReprFlags::IS_C)
2445 pub fn packed(&self) -> bool {
2449 pub fn transparent(&self) -> bool {
2450 self.flags.contains(ReprFlags::IS_TRANSPARENT)
2453 pub fn linear(&self) -> bool {
2454 self.flags.contains(ReprFlags::IS_LINEAR)
2457 pub fn hide_niche(&self) -> bool {
2458 self.flags.contains(ReprFlags::HIDE_NICHE)
2461 /// Returns the discriminant type, given these `repr` options.
2462 /// This must only be called on enums!
2463 pub fn discr_type(&self) -> attr::IntType {
2464 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2467 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2468 /// layout" optimizations, such as representing `Foo<&T>` as a
2470 pub fn inhibit_enum_layout_opt(&self) -> bool {
2471 self.c() || self.int.is_some()
2474 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2475 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2476 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2477 if let Some(pack) = self.pack {
2478 if pack.bytes() == 1 {
2482 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2485 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2486 pub fn inhibit_union_abi_opt(&self) -> bool {
2492 /// Creates a new `AdtDef`.
2497 variants: IndexVec<VariantIdx, VariantDef>,
2500 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
2501 let mut flags = AdtFlags::NO_ADT_FLAGS;
2503 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
2504 debug!("found non-exhaustive variant list for {:?}", did);
2505 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
2508 flags |= match kind {
2509 AdtKind::Enum => AdtFlags::IS_ENUM,
2510 AdtKind::Union => AdtFlags::IS_UNION,
2511 AdtKind::Struct => AdtFlags::IS_STRUCT,
2514 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
2515 flags |= AdtFlags::HAS_CTOR;
2518 let attrs = tcx.get_attrs(did);
2519 if attr::contains_name(&attrs, sym::fundamental) {
2520 flags |= AdtFlags::IS_FUNDAMENTAL;
2522 if Some(did) == tcx.lang_items().phantom_data() {
2523 flags |= AdtFlags::IS_PHANTOM_DATA;
2525 if Some(did) == tcx.lang_items().owned_box() {
2526 flags |= AdtFlags::IS_BOX;
2528 if Some(did) == tcx.lang_items().manually_drop() {
2529 flags |= AdtFlags::IS_MANUALLY_DROP;
2532 AdtDef { did, variants, flags, repr }
2535 /// Returns `true` if this is a struct.
2537 pub fn is_struct(&self) -> bool {
2538 self.flags.contains(AdtFlags::IS_STRUCT)
2541 /// Returns `true` if this is a union.
2543 pub fn is_union(&self) -> bool {
2544 self.flags.contains(AdtFlags::IS_UNION)
2547 /// Returns `true` if this is a enum.
2549 pub fn is_enum(&self) -> bool {
2550 self.flags.contains(AdtFlags::IS_ENUM)
2553 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
2555 pub fn is_variant_list_non_exhaustive(&self) -> bool {
2556 self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
2559 /// Returns the kind of the ADT.
2561 pub fn adt_kind(&self) -> AdtKind {
2564 } else if self.is_union() {
2571 /// Returns a description of this abstract data type.
2572 pub fn descr(&self) -> &'static str {
2573 match self.adt_kind() {
2574 AdtKind::Struct => "struct",
2575 AdtKind::Union => "union",
2576 AdtKind::Enum => "enum",
2580 /// Returns a description of a variant of this abstract data type.
2582 pub fn variant_descr(&self) -> &'static str {
2583 match self.adt_kind() {
2584 AdtKind::Struct => "struct",
2585 AdtKind::Union => "union",
2586 AdtKind::Enum => "variant",
2590 /// If this function returns `true`, it implies that `is_struct` must return `true`.
2592 pub fn has_ctor(&self) -> bool {
2593 self.flags.contains(AdtFlags::HAS_CTOR)
2596 /// Returns `true` if this type is `#[fundamental]` for the purposes
2597 /// of coherence checking.
2599 pub fn is_fundamental(&self) -> bool {
2600 self.flags.contains(AdtFlags::IS_FUNDAMENTAL)
2603 /// Returns `true` if this is `PhantomData<T>`.
2605 pub fn is_phantom_data(&self) -> bool {
2606 self.flags.contains(AdtFlags::IS_PHANTOM_DATA)
2609 /// Returns `true` if this is Box<T>.
2611 pub fn is_box(&self) -> bool {
2612 self.flags.contains(AdtFlags::IS_BOX)
2615 /// Returns `true` if this is `ManuallyDrop<T>`.
2617 pub fn is_manually_drop(&self) -> bool {
2618 self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
2621 /// Returns `true` if this type has a destructor.
2622 pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
2623 self.destructor(tcx).is_some()
2626 /// Asserts this is a struct or union and returns its unique variant.
2627 pub fn non_enum_variant(&self) -> &VariantDef {
2628 assert!(self.is_struct() || self.is_union());
2629 &self.variants[VariantIdx::new(0)]
2633 pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
2634 tcx.predicates_of(self.did)
2637 /// Returns an iterator over all fields contained
2640 pub fn all_fields(&self) -> impl Iterator<Item = &FieldDef> + Clone {
2641 self.variants.iter().flat_map(|v| v.fields.iter())
2644 pub fn is_payloadfree(&self) -> bool {
2645 !self.variants.is_empty() && self.variants.iter().all(|v| v.fields.is_empty())
2648 /// Return a `VariantDef` given a variant id.
2649 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
2650 self.variants.iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
2653 /// Return a `VariantDef` given a constructor id.
2654 pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
2657 .find(|v| v.ctor_def_id == Some(cid))
2658 .expect("variant_with_ctor_id: unknown variant")
2661 /// Return the index of `VariantDef` given a variant id.
2662 pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
2665 .find(|(_, v)| v.def_id == vid)
2666 .expect("variant_index_with_id: unknown variant")
2670 /// Return the index of `VariantDef` given a constructor id.
2671 pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
2674 .find(|(_, v)| v.ctor_def_id == Some(cid))
2675 .expect("variant_index_with_ctor_id: unknown variant")
2679 pub fn variant_of_res(&self, res: Res) -> &VariantDef {
2681 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
2682 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
2683 Res::Def(DefKind::Struct, _)
2684 | Res::Def(DefKind::Union, _)
2685 | Res::Def(DefKind::TyAlias, _)
2686 | Res::Def(DefKind::AssocTy, _)
2688 | Res::SelfCtor(..) => self.non_enum_variant(),
2689 _ => bug!("unexpected res {:?} in variant_of_res", res),
2694 pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
2695 assert!(self.is_enum());
2696 let param_env = tcx.param_env(expr_did);
2697 let repr_type = self.repr.discr_type();
2698 match tcx.const_eval_poly(expr_did) {
2700 let ty = repr_type.to_ty(tcx);
2701 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
2702 trace!("discriminants: {} ({:?})", b, repr_type);
2703 Some(Discr { val: b, ty })
2705 info!("invalid enum discriminant: {:#?}", val);
2706 crate::mir::interpret::struct_error(
2707 tcx.at(tcx.def_span(expr_did)),
2708 "constant evaluation of enum discriminant resulted in non-integer",
2715 let msg = match err {
2716 ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => {
2717 "enum discriminant evaluation failed"
2719 ErrorHandled::TooGeneric => "enum discriminant depends on generics",
2721 tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg);
2728 pub fn discriminants(
2731 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
2732 assert!(self.is_enum());
2733 let repr_type = self.repr.discr_type();
2734 let initial = repr_type.initial_discriminant(tcx);
2735 let mut prev_discr = None::<Discr<'tcx>>;
2736 self.variants.iter_enumerated().map(move |(i, v)| {
2737 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
2738 if let VariantDiscr::Explicit(expr_did) = v.discr {
2739 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
2743 prev_discr = Some(discr);
2750 pub fn variant_range(&self) -> Range<VariantIdx> {
2751 VariantIdx::new(0)..VariantIdx::new(self.variants.len())
2754 /// Computes the discriminant value used by a specific variant.
2755 /// Unlike `discriminants`, this is (amortized) constant-time,
2756 /// only doing at most one query for evaluating an explicit
2757 /// discriminant (the last one before the requested variant),
2758 /// assuming there are no constant-evaluation errors there.
2760 pub fn discriminant_for_variant(
2763 variant_index: VariantIdx,
2765 assert!(self.is_enum());
2766 let (val, offset) = self.discriminant_def_for_variant(variant_index);
2767 let explicit_value = val
2768 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
2769 .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx));
2770 explicit_value.checked_add(tcx, offset as u128).0
2773 /// Yields a `DefId` for the discriminant and an offset to add to it
2774 /// Alternatively, if there is no explicit discriminant, returns the
2775 /// inferred discriminant directly.
2776 pub fn discriminant_def_for_variant(&self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
2777 assert!(!self.variants.is_empty());
2778 let mut explicit_index = variant_index.as_u32();
2781 match self.variants[VariantIdx::from_u32(explicit_index)].discr {
2782 ty::VariantDiscr::Relative(0) => {
2786 ty::VariantDiscr::Relative(distance) => {
2787 explicit_index -= distance;
2789 ty::VariantDiscr::Explicit(did) => {
2790 expr_did = Some(did);
2795 (expr_did, variant_index.as_u32() - explicit_index)
2798 pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
2799 tcx.adt_destructor(self.did)
2802 /// Returns a list of types such that `Self: Sized` if and only
2803 /// if that type is `Sized`, or `TyErr` if this type is recursive.
2805 /// Oddly enough, checking that the sized-constraint is `Sized` is
2806 /// actually more expressive than checking all members:
2807 /// the `Sized` trait is inductive, so an associated type that references
2808 /// `Self` would prevent its containing ADT from being `Sized`.
2810 /// Due to normalization being eager, this applies even if
2811 /// the associated type is behind a pointer (e.g., issue #31299).
2812 pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] {
2813 tcx.adt_sized_constraint(self.did).0
2817 impl<'tcx> FieldDef {
2818 /// Returns the type of this field. The `subst` is typically obtained
2819 /// via the second field of `TyKind::AdtDef`.
2820 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2821 tcx.type_of(self.did).subst(tcx, subst)
2825 /// Represents the various closure traits in the language. This
2826 /// will determine the type of the environment (`self`, in the
2827 /// desugaring) argument that the closure expects.
2829 /// You can get the environment type of a closure using
2830 /// `tcx.closure_env_ty()`.
2831 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
2832 #[derive(HashStable)]
2833 pub enum ClosureKind {
2834 // Warning: Ordering is significant here! The ordering is chosen
2835 // because the trait Fn is a subtrait of FnMut and so in turn, and
2836 // hence we order it so that Fn < FnMut < FnOnce.
2842 impl<'tcx> ClosureKind {
2843 // This is the initial value used when doing upvar inference.
2844 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2846 pub fn trait_did(&self, tcx: TyCtxt<'tcx>) -> DefId {
2848 ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem, None),
2849 ClosureKind::FnMut => tcx.require_lang_item(FnMutTraitLangItem, None),
2850 ClosureKind::FnOnce => tcx.require_lang_item(FnOnceTraitLangItem, None),
2854 /// Returns `true` if this a type that impls this closure kind
2855 /// must also implement `other`.
2856 pub fn extends(self, other: ty::ClosureKind) -> bool {
2857 match (self, other) {
2858 (ClosureKind::Fn, ClosureKind::Fn) => true,
2859 (ClosureKind::Fn, ClosureKind::FnMut) => true,
2860 (ClosureKind::Fn, ClosureKind::FnOnce) => true,
2861 (ClosureKind::FnMut, ClosureKind::FnMut) => true,
2862 (ClosureKind::FnMut, ClosureKind::FnOnce) => true,
2863 (ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
2868 /// Returns the representative scalar type for this closure kind.
2869 /// See `TyS::to_opt_closure_kind` for more details.
2870 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2872 ty::ClosureKind::Fn => tcx.types.i8,
2873 ty::ClosureKind::FnMut => tcx.types.i16,
2874 ty::ClosureKind::FnOnce => tcx.types.i32,
2880 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2882 hir::Mutability::Mut => MutBorrow,
2883 hir::Mutability::Not => ImmBorrow,
2887 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2888 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2889 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2891 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2893 MutBorrow => hir::Mutability::Mut,
2894 ImmBorrow => hir::Mutability::Not,
2896 // We have no type corresponding to a unique imm borrow, so
2897 // use `&mut`. It gives all the capabilities of an `&uniq`
2898 // and hence is a safe "over approximation".
2899 UniqueImmBorrow => hir::Mutability::Mut,
2903 pub fn to_user_str(&self) -> &'static str {
2905 MutBorrow => "mutable",
2906 ImmBorrow => "immutable",
2907 UniqueImmBorrow => "uniquely immutable",
2912 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
2914 #[derive(Debug, PartialEq, Eq)]
2915 pub enum ImplOverlapKind {
2916 /// These impls are always allowed to overlap.
2918 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
2921 /// These impls are allowed to overlap, but that raises
2922 /// an issue #33140 future-compatibility warning.
2924 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2925 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2927 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2928 /// that difference, making what reduces to the following set of impls:
2932 /// impl Trait for dyn Send + Sync {}
2933 /// impl Trait for dyn Sync + Send {}
2936 /// Obviously, once we made these types be identical, that code causes a coherence
2937 /// error and a fairly big headache for us. However, luckily for us, the trait
2938 /// `Trait` used in this case is basically a marker trait, and therefore having
2939 /// overlapping impls for it is sound.
2941 /// To handle this, we basically regard the trait as a marker trait, with an additional
2942 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2943 /// it has the following restrictions:
2945 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2947 /// 2. The trait-ref of both impls must be equal.
2948 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2950 /// 4. Neither of the impls can have any where-clauses.
2952 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2956 impl<'tcx> TyCtxt<'tcx> {
2957 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
2958 self.typeck(self.hir().body_owner_def_id(body))
2961 /// Returns an iterator of the `DefId`s for all body-owners in this
2962 /// crate. If you would prefer to iterate over the bodies
2963 /// themselves, you can do `self.hir().krate().body_ids.iter()`.
2964 pub fn body_owners(self) -> impl Iterator<Item = LocalDefId> + Captures<'tcx> + 'tcx {
2969 .map(move |&body_id| self.hir().body_owner_def_id(body_id))
2972 pub fn par_body_owners<F: Fn(LocalDefId) + sync::Sync + sync::Send>(self, f: F) {
2973 par_iter(&self.hir().krate().body_ids)
2974 .for_each(|&body_id| f(self.hir().body_owner_def_id(body_id)));
2977 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
2978 self.associated_items(id)
2979 .in_definition_order()
2980 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
2983 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
2986 .and_then(|def_id| self.hir().get(self.hir().as_local_hir_id(def_id)).ident())
2989 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2990 let is_associated_item = if let Some(def_id) = def_id.as_local() {
2991 match self.hir().get(self.hir().as_local_hir_id(def_id)) {
2992 Node::TraitItem(_) | Node::ImplItem(_) => true,
2996 match self.def_kind(def_id) {
2997 DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy => true,
3002 is_associated_item.then(|| self.associated_item(def_id))
3005 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
3006 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
3009 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
3010 variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id))
3013 /// Returns `true` if the impls are the same polarity and the trait either
3014 /// has no items or is annotated `#[marker]` and prevents item overrides.
3015 pub fn impls_are_allowed_to_overlap(
3019 ) -> Option<ImplOverlapKind> {
3020 // If either trait impl references an error, they're allowed to overlap,
3021 // as one of them essentially doesn't exist.
3022 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
3023 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
3025 return Some(ImplOverlapKind::Permitted { marker: false });
3028 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
3029 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
3030 // `#[rustc_reservation_impl]` impls don't overlap with anything
3032 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
3035 return Some(ImplOverlapKind::Permitted { marker: false });
3037 (ImplPolarity::Positive, ImplPolarity::Negative)
3038 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
3039 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
3041 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
3046 (ImplPolarity::Positive, ImplPolarity::Positive)
3047 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
3050 let is_marker_overlap = {
3051 let is_marker_impl = |def_id: DefId| -> bool {
3052 let trait_ref = self.impl_trait_ref(def_id);
3053 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
3055 is_marker_impl(def_id1) && is_marker_impl(def_id2)
3058 if is_marker_overlap {
3060 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
3063 Some(ImplOverlapKind::Permitted { marker: true })
3065 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
3066 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
3067 if self_ty1 == self_ty2 {
3069 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
3072 return Some(ImplOverlapKind::Issue33140);
3075 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
3076 def_id1, def_id2, self_ty1, self_ty2
3082 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
3087 /// Returns `ty::VariantDef` if `res` refers to a struct,
3088 /// or variant or their constructors, panics otherwise.
3089 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
3091 Res::Def(DefKind::Variant, did) => {
3092 let enum_did = self.parent(did).unwrap();
3093 self.adt_def(enum_did).variant_with_id(did)
3095 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
3096 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
3097 let variant_did = self.parent(variant_ctor_did).unwrap();
3098 let enum_did = self.parent(variant_did).unwrap();
3099 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
3101 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
3102 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
3103 self.adt_def(struct_did).non_enum_variant()
3105 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
3109 pub fn item_name(self, id: DefId) -> Symbol {
3110 if id.index == CRATE_DEF_INDEX {
3111 self.original_crate_name(id.krate)
3113 let def_key = self.def_key(id);
3114 match def_key.disambiguated_data.data {
3115 // The name of a constructor is that of its parent.
3116 rustc_hir::definitions::DefPathData::Ctor => {
3117 self.item_name(DefId { krate: id.krate, index: def_key.parent.unwrap() })
3119 _ => def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
3120 bug!("item_name: no name for {:?}", self.def_path(id));
3126 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
3127 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
3129 ty::InstanceDef::Item(def) => {
3130 if let Some((did, param_did)) = def.as_const_arg() {
3131 self.optimized_mir_of_const_arg((did, param_did))
3133 self.optimized_mir(def.did)
3136 ty::InstanceDef::VtableShim(..)
3137 | ty::InstanceDef::ReifyShim(..)
3138 | ty::InstanceDef::Intrinsic(..)
3139 | ty::InstanceDef::FnPtrShim(..)
3140 | ty::InstanceDef::Virtual(..)
3141 | ty::InstanceDef::ClosureOnceShim { .. }
3142 | ty::InstanceDef::DropGlue(..)
3143 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
3147 /// Gets the attributes of a definition.
3148 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
3149 if let Some(did) = did.as_local() {
3150 self.hir().attrs(self.hir().as_local_hir_id(did))
3152 self.item_attrs(did)
3156 /// Determines whether an item is annotated with an attribute.
3157 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
3158 attr::contains_name(&self.get_attrs(did), attr)
3161 /// Returns `true` if this is an `auto trait`.
3162 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
3163 self.trait_def(trait_def_id).has_auto_impl
3166 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
3167 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
3170 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
3171 /// If it implements no trait, returns `None`.
3172 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
3173 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
3176 /// If the given defid describes a method belonging to an impl, returns the
3177 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
3178 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
3179 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
3180 TraitContainer(_) => None,
3181 ImplContainer(def_id) => Some(def_id),
3185 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
3186 /// with the name of the crate containing the impl.
3187 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
3188 if let Some(impl_did) = impl_did.as_local() {
3189 let hir_id = self.hir().as_local_hir_id(impl_did);
3190 Ok(self.hir().span(hir_id))
3192 Err(self.crate_name(impl_did.krate))
3196 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
3197 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
3198 /// definition's parent/scope to perform comparison.
3199 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
3200 // We could use `Ident::eq` here, but we deliberately don't. The name
3201 // comparison fails frequently, and we want to avoid the expensive
3202 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
3203 use_name.name == def_name.name
3207 .hygienic_eq(def_name.span.ctxt(), self.expansion_that_defined(def_parent_def_id))
3210 fn expansion_that_defined(self, scope: DefId) -> ExpnId {
3211 match scope.as_local() {
3212 Some(scope) => self.hir().definitions().expansion_that_defined(scope),
3213 None => ExpnId::root(),
3217 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
3218 ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope));
3222 pub fn adjust_ident_and_get_scope(
3227 ) -> (Ident, DefId) {
3229 match ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope))
3231 Some(actual_expansion) => {
3232 self.hir().definitions().parent_module_of_macro_def(actual_expansion)
3234 None => self.parent_module(block).to_def_id(),
3239 pub fn is_object_safe(self, key: DefId) -> bool {
3240 self.object_safety_violations(key).is_empty()
3244 #[derive(Clone, HashStable)]
3245 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
3247 /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition.
3248 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
3249 if let Some(def_id) = def_id.as_local() {
3250 if let Node::Item(item) = tcx.hir().get(tcx.hir().as_local_hir_id(def_id)) {
3251 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
3252 return opaque_ty.impl_trait_fn;
3259 pub fn provide(providers: &mut ty::query::Providers) {
3260 context::provide(providers);
3261 erase_regions::provide(providers);
3262 layout::provide(providers);
3263 super::util::bug::provide(providers);
3264 *providers = ty::query::Providers {
3265 trait_impls_of: trait_def::trait_impls_of_provider,
3266 all_local_trait_impls: trait_def::all_local_trait_impls,
3271 /// A map for the local crate mapping each type to a vector of its
3272 /// inherent impls. This is not meant to be used outside of coherence;
3273 /// rather, you should request the vector for a specific type via
3274 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
3275 /// (constructing this map requires touching the entire crate).
3276 #[derive(Clone, Debug, Default, HashStable)]
3277 pub struct CrateInherentImpls {
3278 pub inherent_impls: DefIdMap<Vec<DefId>>,
3281 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, HashStable)]
3282 pub struct SymbolName<'tcx> {
3283 /// `&str` gives a consistent ordering, which ensures reproducible builds.
3284 pub name: &'tcx str,
3287 impl<'tcx> SymbolName<'tcx> {
3288 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
3290 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
3295 impl<'tcx> fmt::Display for SymbolName<'tcx> {
3296 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3297 fmt::Display::fmt(&self.name, fmt)
3301 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
3302 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3303 fmt::Display::fmt(&self.name, fmt)
3307 impl<'tcx> rustc_serialize::UseSpecializedEncodable for SymbolName<'tcx> {
3308 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
3309 s.emit_str(self.name)
3313 // The decoding takes place in `decode_symbol_name()`.
3314 impl<'tcx> rustc_serialize::UseSpecializedDecodable for SymbolName<'tcx> {}