1 // ignore-tidy-filelength
3 pub use self::fold::{TypeFoldable, TypeVisitor};
4 pub use self::AssocItemContainer::*;
5 pub use self::BorrowKind::*;
6 pub use self::IntVarValue::*;
7 pub use self::Variance::*;
9 use crate::arena::Arena;
10 use crate::hir::exports::ExportMap;
11 use crate::hir::map as hir_map;
13 use crate::ich::Fingerprint;
14 use crate::ich::StableHashingContext;
15 use crate::infer::canonical::Canonical;
16 use crate::middle::cstore::CrateStoreDyn;
17 use crate::middle::lang_items::{FnMutTraitLangItem, FnOnceTraitLangItem, FnTraitLangItem};
18 use crate::middle::resolve_lifetime::ObjectLifetimeDefault;
19 use crate::mir::interpret::ErrorHandled;
20 use crate::mir::GeneratorLayout;
21 use crate::mir::ReadOnlyBodyAndCache;
22 use crate::session::DataTypeKind;
23 use crate::traits::{self, Reveal};
25 use crate::ty::layout::VariantIdx;
26 use crate::ty::subst::{InternalSubsts, Subst, SubstsRef};
27 use crate::ty::util::{Discr, IntTypeExt};
28 use crate::ty::walk::TypeWalker;
29 use rustc_attr as attr;
30 use rustc_data_structures::captures::Captures;
31 use rustc_data_structures::fx::FxHashMap;
32 use rustc_data_structures::fx::FxIndexMap;
33 use rustc_data_structures::sorted_map::SortedIndexMultiMap;
34 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
35 use rustc_data_structures::sync::{self, par_iter, Lrc, ParallelIterator};
37 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Namespace, Res};
38 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX, LOCAL_CRATE};
39 use rustc_hir::{Constness, GlobMap, Node, TraitMap};
40 use rustc_index::vec::{Idx, IndexVec};
41 use rustc_macros::HashStable;
42 use rustc_serialize::{self, Encodable, Encoder};
43 use rustc_span::hygiene::ExpnId;
44 use rustc_span::symbol::{kw, sym, Symbol};
46 use rustc_target::abi::Align;
47 use syntax::ast::{self, Ident, Name};
48 use syntax::node_id::{NodeId, NodeMap, NodeSet};
50 use std::cell::RefCell;
51 use std::cmp::{self, Ordering};
53 use std::hash::{Hash, Hasher};
59 pub use self::sty::BoundRegion::*;
60 pub use self::sty::InferTy::*;
61 pub use self::sty::RegionKind;
62 pub use self::sty::RegionKind::*;
63 pub use self::sty::TyKind::*;
64 pub use self::sty::{Binder, BoundTy, BoundTyKind, BoundVar, DebruijnIndex, INNERMOST};
65 pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
66 pub use self::sty::{CanonicalPolyFnSig, FnSig, GenSig, PolyFnSig, PolyGenSig};
67 pub use self::sty::{ClosureSubsts, GeneratorSubsts, TypeAndMut, UpvarSubsts};
68 pub use self::sty::{Const, ConstKind, ExistentialProjection, PolyExistentialProjection};
69 pub use self::sty::{ConstVid, FloatVid, IntVid, RegionVid, TyVid};
70 pub use self::sty::{ExistentialPredicate, InferConst, InferTy, ParamConst, ParamTy, ProjectionTy};
71 pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
72 pub use self::sty::{PolyTraitRef, TraitRef, TyKind};
73 pub use crate::ty::diagnostics::*;
75 pub use self::binding::BindingMode;
76 pub use self::binding::BindingMode::*;
78 pub use self::context::{keep_local, tls, FreeRegionInfo, TyCtxt};
79 pub use self::context::{
80 CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, ResolvedOpaqueTy,
81 UserType, UserTypeAnnotationIndex,
83 pub use self::context::{
84 CtxtInterners, GeneratorInteriorTypeCause, GlobalCtxt, Lift, TypeckTables,
87 pub use self::instance::RESOLVE_INSTANCE;
88 pub use self::instance::{Instance, InstanceDef};
90 pub use self::trait_def::TraitDef;
92 pub use self::query::queries;
105 pub mod free_region_map;
106 pub mod inhabitedness;
108 pub mod normalize_erasing_regions;
122 mod structural_impls;
127 pub struct ResolverOutputs {
128 pub definitions: hir_map::Definitions,
129 pub cstore: Box<CrateStoreDyn>,
130 pub extern_crate_map: NodeMap<CrateNum>,
131 pub trait_map: TraitMap<NodeId>,
132 pub maybe_unused_trait_imports: NodeSet,
133 pub maybe_unused_extern_crates: Vec<(NodeId, Span)>,
134 pub export_map: ExportMap<NodeId>,
135 pub glob_map: GlobMap,
136 /// Extern prelude entries. The value is `true` if the entry was introduced
137 /// via `extern crate` item and not `--extern` option or compiler built-in.
138 pub extern_prelude: FxHashMap<Name, bool>,
141 #[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable)]
142 pub enum AssocItemContainer {
143 TraitContainer(DefId),
144 ImplContainer(DefId),
147 impl AssocItemContainer {
148 /// Asserts that this is the `DefId` of an associated item declared
149 /// in a trait, and returns the trait `DefId`.
150 pub fn assert_trait(&self) -> DefId {
152 TraitContainer(id) => id,
153 _ => bug!("associated item has wrong container type: {:?}", self),
157 pub fn id(&self) -> DefId {
159 TraitContainer(id) => id,
160 ImplContainer(id) => id,
165 /// The "header" of an impl is everything outside the body: a Self type, a trait
166 /// ref (in the case of a trait impl), and a set of predicates (from the
167 /// bounds / where-clauses).
168 #[derive(Clone, Debug, TypeFoldable)]
169 pub struct ImplHeader<'tcx> {
170 pub impl_def_id: DefId,
171 pub self_ty: Ty<'tcx>,
172 pub trait_ref: Option<TraitRef<'tcx>>,
173 pub predicates: Vec<Predicate<'tcx>>,
176 #[derive(Copy, Clone, PartialEq, RustcEncodable, RustcDecodable, HashStable)]
177 pub enum ImplPolarity {
178 /// `impl Trait for Type`
180 /// `impl !Trait for Type`
182 /// `#[rustc_reservation_impl] impl Trait for Type`
184 /// This is a "stability hack", not a real Rust feature.
185 /// See #64631 for details.
189 #[derive(Copy, Clone, Debug, PartialEq, HashStable)]
190 pub struct AssocItem {
192 #[stable_hasher(project(name))]
196 pub defaultness: hir::Defaultness,
197 pub container: AssocItemContainer,
199 /// Whether this is a method with an explicit self
200 /// as its first argument, allowing method calls.
201 pub method_has_self_argument: bool,
204 #[derive(Copy, Clone, PartialEq, Debug, HashStable)]
213 pub fn suggestion_descr(&self) -> &'static str {
215 ty::AssocKind::Method => "method call",
216 ty::AssocKind::Type | ty::AssocKind::OpaqueTy => "associated type",
217 ty::AssocKind::Const => "associated constant",
221 pub fn namespace(&self) -> Namespace {
223 ty::AssocKind::OpaqueTy | ty::AssocKind::Type => Namespace::TypeNS,
224 ty::AssocKind::Const | ty::AssocKind::Method => Namespace::ValueNS,
230 pub fn def_kind(&self) -> DefKind {
232 AssocKind::Const => DefKind::AssocConst,
233 AssocKind::Method => DefKind::Method,
234 AssocKind::Type => DefKind::AssocTy,
235 AssocKind::OpaqueTy => DefKind::AssocOpaqueTy,
239 /// Tests whether the associated item admits a non-trivial implementation
241 pub fn relevant_for_never(&self) -> bool {
243 AssocKind::OpaqueTy | AssocKind::Const | AssocKind::Type => true,
244 // FIXME(canndrew): Be more thorough here, check if any argument is uninhabited.
245 AssocKind::Method => !self.method_has_self_argument,
249 pub fn signature(&self, tcx: TyCtxt<'_>) -> String {
251 ty::AssocKind::Method => {
252 // We skip the binder here because the binder would deanonymize all
253 // late-bound regions, and we don't want method signatures to show up
254 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
255 // regions just fine, showing `fn(&MyType)`.
256 tcx.fn_sig(self.def_id).skip_binder().to_string()
258 ty::AssocKind::Type => format!("type {};", self.ident),
259 // FIXME(type_alias_impl_trait): we should print bounds here too.
260 ty::AssocKind::OpaqueTy => format!("type {};", self.ident),
261 ty::AssocKind::Const => {
262 format!("const {}: {:?};", self.ident, tcx.type_of(self.def_id))
268 /// A list of `ty::AssocItem`s in definition order that allows for efficient lookup by name.
270 /// When doing lookup by name, we try to postpone hygienic comparison for as long as possible since
271 /// it is relatively expensive. Instead, items are indexed by `Symbol` and hygienic comparison is
272 /// done only on items with the same name.
273 #[derive(Debug, Clone, PartialEq, HashStable)]
274 pub struct AssociatedItems {
275 items: SortedIndexMultiMap<u32, Symbol, ty::AssocItem>,
278 impl AssociatedItems {
279 /// Constructs an `AssociatedItems` map from a series of `ty::AssocItem`s in definition order.
280 pub fn new(items_in_def_order: impl IntoIterator<Item = ty::AssocItem>) -> Self {
281 let items = items_in_def_order.into_iter().map(|item| (item.ident.name, item)).collect();
282 AssociatedItems { items }
285 /// Returns a slice of associated items in the order they were defined.
287 /// New code should avoid relying on definition order. If you need a particular associated item
288 /// for a known trait, make that trait a lang item instead of indexing this array.
289 pub fn in_definition_order(&self) -> impl '_ + Iterator<Item = &ty::AssocItem> {
290 self.items.iter().map(|(_, v)| v)
293 /// Returns an iterator over all associated items with the given name, ignoring hygiene.
294 pub fn filter_by_name_unhygienic(
297 ) -> impl '_ + Iterator<Item = &ty::AssocItem> {
298 self.items.get_by_key(&name)
301 /// Returns an iterator over all associated items with the given name.
303 /// Multiple items may have the same name if they are in different `Namespace`s. For example,
304 /// an associated type can have the same name as a method. Use one of the `find_by_name_and_*`
305 /// methods below if you know which item you are looking for.
306 pub fn filter_by_name(
310 parent_def_id: DefId,
311 ) -> impl 'a + Iterator<Item = &'a ty::AssocItem> {
312 self.filter_by_name_unhygienic(ident.name)
313 .filter(move |item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
316 /// Returns the associated item with the given name and `AssocKind`, if one exists.
317 pub fn find_by_name_and_kind(
322 parent_def_id: DefId,
323 ) -> Option<&ty::AssocItem> {
324 self.filter_by_name_unhygienic(ident.name)
325 .filter(|item| item.kind == kind)
326 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
329 /// Returns the associated item with the given name in the given `Namespace`, if one exists.
330 pub fn find_by_name_and_namespace(
335 parent_def_id: DefId,
336 ) -> Option<&ty::AssocItem> {
337 self.filter_by_name_unhygienic(ident.name)
338 .filter(|item| item.kind.namespace() == ns)
339 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
343 #[derive(Clone, Debug, PartialEq, Eq, Copy, RustcEncodable, RustcDecodable, HashStable)]
344 pub enum Visibility {
345 /// Visible everywhere (including in other crates).
347 /// Visible only in the given crate-local module.
349 /// Not visible anywhere in the local crate. This is the visibility of private external items.
353 pub trait DefIdTree: Copy {
354 fn parent(self, id: DefId) -> Option<DefId>;
356 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
357 if descendant.krate != ancestor.krate {
361 while descendant != ancestor {
362 match self.parent(descendant) {
363 Some(parent) => descendant = parent,
364 None => return false,
371 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
372 fn parent(self, id: DefId) -> Option<DefId> {
373 self.def_key(id).parent.map(|index| DefId { index: index, ..id })
378 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
379 match visibility.node {
380 hir::VisibilityKind::Public => Visibility::Public,
381 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
382 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
383 // If there is no resolution, `resolve` will have already reported an error, so
384 // assume that the visibility is public to avoid reporting more privacy errors.
385 Res::Err => Visibility::Public,
386 def => Visibility::Restricted(def.def_id()),
388 hir::VisibilityKind::Inherited => {
389 Visibility::Restricted(tcx.hir().get_module_parent(id))
394 /// Returns `true` if an item with this visibility is accessible from the given block.
395 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
396 let restriction = match self {
397 // Public items are visible everywhere.
398 Visibility::Public => return true,
399 // Private items from other crates are visible nowhere.
400 Visibility::Invisible => return false,
401 // Restricted items are visible in an arbitrary local module.
402 Visibility::Restricted(other) if other.krate != module.krate => return false,
403 Visibility::Restricted(module) => module,
406 tree.is_descendant_of(module, restriction)
409 /// Returns `true` if this visibility is at least as accessible as the given visibility
410 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
411 let vis_restriction = match vis {
412 Visibility::Public => return self == Visibility::Public,
413 Visibility::Invisible => return true,
414 Visibility::Restricted(module) => module,
417 self.is_accessible_from(vis_restriction, tree)
420 // Returns `true` if this item is visible anywhere in the local crate.
421 pub fn is_visible_locally(self) -> bool {
423 Visibility::Public => true,
424 Visibility::Restricted(def_id) => def_id.is_local(),
425 Visibility::Invisible => false,
430 #[derive(Copy, Clone, PartialEq, RustcDecodable, RustcEncodable, HashStable)]
432 Covariant, // T<A> <: T<B> iff A <: B -- e.g., function return type
433 Invariant, // T<A> <: T<B> iff B == A -- e.g., type of mutable cell
434 Contravariant, // T<A> <: T<B> iff B <: A -- e.g., function param type
435 Bivariant, // T<A> <: T<B> -- e.g., unused type parameter
438 /// The crate variances map is computed during typeck and contains the
439 /// variance of every item in the local crate. You should not use it
440 /// directly, because to do so will make your pass dependent on the
441 /// HIR of every item in the local crate. Instead, use
442 /// `tcx.variances_of()` to get the variance for a *particular*
444 #[derive(HashStable)]
445 pub struct CrateVariancesMap<'tcx> {
446 /// For each item with generics, maps to a vector of the variance
447 /// of its generics. If an item has no generics, it will have no
449 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
453 /// `a.xform(b)` combines the variance of a context with the
454 /// variance of a type with the following meaning. If we are in a
455 /// context with variance `a`, and we encounter a type argument in
456 /// a position with variance `b`, then `a.xform(b)` is the new
457 /// variance with which the argument appears.
463 /// Here, the "ambient" variance starts as covariant. `*mut T` is
464 /// invariant with respect to `T`, so the variance in which the
465 /// `Vec<i32>` appears is `Covariant.xform(Invariant)`, which
466 /// yields `Invariant`. Now, the type `Vec<T>` is covariant with
467 /// respect to its type argument `T`, and hence the variance of
468 /// the `i32` here is `Invariant.xform(Covariant)`, which results
469 /// (again) in `Invariant`.
473 /// fn(*const Vec<i32>, *mut Vec<i32)
475 /// The ambient variance is covariant. A `fn` type is
476 /// contravariant with respect to its parameters, so the variance
477 /// within which both pointer types appear is
478 /// `Covariant.xform(Contravariant)`, or `Contravariant`. `*const
479 /// T` is covariant with respect to `T`, so the variance within
480 /// which the first `Vec<i32>` appears is
481 /// `Contravariant.xform(Covariant)` or `Contravariant`. The same
482 /// is true for its `i32` argument. In the `*mut T` case, the
483 /// variance of `Vec<i32>` is `Contravariant.xform(Invariant)`,
484 /// and hence the outermost type is `Invariant` with respect to
485 /// `Vec<i32>` (and its `i32` argument).
487 /// Source: Figure 1 of "Taming the Wildcards:
488 /// Combining Definition- and Use-Site Variance" published in PLDI'11.
489 pub fn xform(self, v: ty::Variance) -> ty::Variance {
491 // Figure 1, column 1.
492 (ty::Covariant, ty::Covariant) => ty::Covariant,
493 (ty::Covariant, ty::Contravariant) => ty::Contravariant,
494 (ty::Covariant, ty::Invariant) => ty::Invariant,
495 (ty::Covariant, ty::Bivariant) => ty::Bivariant,
497 // Figure 1, column 2.
498 (ty::Contravariant, ty::Covariant) => ty::Contravariant,
499 (ty::Contravariant, ty::Contravariant) => ty::Covariant,
500 (ty::Contravariant, ty::Invariant) => ty::Invariant,
501 (ty::Contravariant, ty::Bivariant) => ty::Bivariant,
503 // Figure 1, column 3.
504 (ty::Invariant, _) => ty::Invariant,
506 // Figure 1, column 4.
507 (ty::Bivariant, _) => ty::Bivariant,
512 // Contains information needed to resolve types and (in the future) look up
513 // the types of AST nodes.
514 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
515 pub struct CReaderCacheKey {
520 // Flags that we track on types. These flags are propagated upwards
521 // through the type during type construction, so that we can quickly
522 // check whether the type has various kinds of types in it without
523 // recursing over the type itself.
525 pub struct TypeFlags: u32 {
526 const HAS_PARAMS = 1 << 0;
527 const HAS_TY_INFER = 1 << 1;
528 const HAS_RE_INFER = 1 << 2;
529 const HAS_RE_PLACEHOLDER = 1 << 3;
531 /// Does this have any `ReEarlyBound` regions? Used to
532 /// determine whether substitition is required, since those
533 /// represent regions that are bound in a `ty::Generics` and
534 /// hence may be substituted.
535 const HAS_RE_EARLY_BOUND = 1 << 4;
537 /// Does this have any region that "appears free" in the type?
538 /// Basically anything but `ReLateBound` and `ReErased`.
539 const HAS_FREE_REGIONS = 1 << 5;
541 /// Is an error type reachable?
542 const HAS_TY_ERR = 1 << 6;
543 const HAS_PROJECTION = 1 << 7;
545 // FIXME: Rename this to the actual property since it's used for generators too
546 const HAS_TY_CLOSURE = 1 << 8;
548 /// `true` if there are "names" of types and regions and so forth
549 /// that are local to a particular fn
550 const HAS_FREE_LOCAL_NAMES = 1 << 9;
552 /// Present if the type belongs in a local type context.
553 /// Only set for Infer other than Fresh.
554 const KEEP_IN_LOCAL_TCX = 1 << 10;
556 /// Does this have any `ReLateBound` regions? Used to check
557 /// if a global bound is safe to evaluate.
558 const HAS_RE_LATE_BOUND = 1 << 11;
560 /// Does this have any `ReErased` regions?
561 const HAS_RE_ERASED = 1 << 12;
563 const HAS_TY_PLACEHOLDER = 1 << 13;
565 const HAS_CT_INFER = 1 << 14;
566 const HAS_CT_PLACEHOLDER = 1 << 15;
567 /// Does this have any [Opaque] types.
568 const HAS_TY_OPAQUE = 1 << 16;
570 const NEEDS_SUBST = TypeFlags::HAS_PARAMS.bits |
571 TypeFlags::HAS_RE_EARLY_BOUND.bits;
573 /// Flags representing the nominal content of a type,
574 /// computed by FlagsComputation. If you add a new nominal
575 /// flag, it should be added here too.
576 const NOMINAL_FLAGS = TypeFlags::HAS_PARAMS.bits |
577 TypeFlags::HAS_TY_INFER.bits |
578 TypeFlags::HAS_RE_INFER.bits |
579 TypeFlags::HAS_RE_PLACEHOLDER.bits |
580 TypeFlags::HAS_RE_EARLY_BOUND.bits |
581 TypeFlags::HAS_FREE_REGIONS.bits |
582 TypeFlags::HAS_TY_ERR.bits |
583 TypeFlags::HAS_PROJECTION.bits |
584 TypeFlags::HAS_TY_CLOSURE.bits |
585 TypeFlags::HAS_FREE_LOCAL_NAMES.bits |
586 TypeFlags::KEEP_IN_LOCAL_TCX.bits |
587 TypeFlags::HAS_RE_LATE_BOUND.bits |
588 TypeFlags::HAS_RE_ERASED.bits |
589 TypeFlags::HAS_TY_PLACEHOLDER.bits |
590 TypeFlags::HAS_CT_INFER.bits |
591 TypeFlags::HAS_CT_PLACEHOLDER.bits |
592 TypeFlags::HAS_TY_OPAQUE.bits;
596 #[allow(rustc::usage_of_ty_tykind)]
597 pub struct TyS<'tcx> {
598 pub kind: TyKind<'tcx>,
599 pub flags: TypeFlags,
601 /// This is a kind of confusing thing: it stores the smallest
604 /// (a) the binder itself captures nothing but
605 /// (b) all the late-bound things within the type are captured
606 /// by some sub-binder.
608 /// So, for a type without any late-bound things, like `u32`, this
609 /// will be *innermost*, because that is the innermost binder that
610 /// captures nothing. But for a type `&'D u32`, where `'D` is a
611 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
612 /// -- the binder itself does not capture `D`, but `D` is captured
613 /// by an inner binder.
615 /// We call this concept an "exclusive" binder `D` because all
616 /// De Bruijn indices within the type are contained within `0..D`
618 outer_exclusive_binder: ty::DebruijnIndex,
621 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
622 #[cfg(target_arch = "x86_64")]
623 static_assert_size!(TyS<'_>, 32);
625 impl<'tcx> Ord for TyS<'tcx> {
626 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
627 self.kind.cmp(&other.kind)
631 impl<'tcx> PartialOrd for TyS<'tcx> {
632 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
633 Some(self.kind.cmp(&other.kind))
637 impl<'tcx> PartialEq for TyS<'tcx> {
639 fn eq(&self, other: &TyS<'tcx>) -> bool {
643 impl<'tcx> Eq for TyS<'tcx> {}
645 impl<'tcx> Hash for TyS<'tcx> {
646 fn hash<H: Hasher>(&self, s: &mut H) {
647 (self as *const TyS<'_>).hash(s)
651 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ty::TyS<'tcx> {
652 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
656 // The other fields just provide fast access to information that is
657 // also contained in `kind`, so no need to hash them.
660 outer_exclusive_binder: _,
663 kind.hash_stable(hcx, hasher);
667 #[rustc_diagnostic_item = "Ty"]
668 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
670 impl<'tcx> rustc_serialize::UseSpecializedEncodable for Ty<'tcx> {}
671 impl<'tcx> rustc_serialize::UseSpecializedDecodable for Ty<'tcx> {}
673 pub type CanonicalTy<'tcx> = Canonical<'tcx, Ty<'tcx>>;
676 /// A dummy type used to force `List` to be unsized while not requiring references to it be wide
678 type OpaqueListContents;
681 /// A wrapper for slices with the additional invariant
682 /// that the slice is interned and no other slice with
683 /// the same contents can exist in the same context.
684 /// This means we can use pointer for both
685 /// equality comparisons and hashing.
686 /// Note: `Slice` was already taken by the `Ty`.
691 opaque: OpaqueListContents,
694 unsafe impl<T: Sync> Sync for List<T> {}
696 impl<T: Copy> List<T> {
698 fn from_arena<'tcx>(arena: &'tcx Arena<'tcx>, slice: &[T]) -> &'tcx List<T> {
699 assert!(!mem::needs_drop::<T>());
700 assert!(mem::size_of::<T>() != 0);
701 assert!(slice.len() != 0);
703 // Align up the size of the len (usize) field
704 let align = mem::align_of::<T>();
705 let align_mask = align - 1;
706 let offset = mem::size_of::<usize>();
707 let offset = (offset + align_mask) & !align_mask;
709 let size = offset + slice.len() * mem::size_of::<T>();
713 .alloc_raw(size, cmp::max(mem::align_of::<T>(), mem::align_of::<usize>()));
715 let result = &mut *(mem.as_mut_ptr() as *mut List<T>);
717 result.len = slice.len();
719 // Write the elements
720 let arena_slice = slice::from_raw_parts_mut(result.data.as_mut_ptr(), result.len);
721 arena_slice.copy_from_slice(slice);
728 impl<T: fmt::Debug> fmt::Debug for List<T> {
729 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
734 impl<T: Encodable> Encodable for List<T> {
736 fn encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
741 impl<T> Ord for List<T>
745 fn cmp(&self, other: &List<T>) -> Ordering {
746 if self == other { Ordering::Equal } else { <[T] as Ord>::cmp(&**self, &**other) }
750 impl<T> PartialOrd for List<T>
754 fn partial_cmp(&self, other: &List<T>) -> Option<Ordering> {
756 Some(Ordering::Equal)
758 <[T] as PartialOrd>::partial_cmp(&**self, &**other)
763 impl<T: PartialEq> PartialEq for List<T> {
765 fn eq(&self, other: &List<T>) -> bool {
769 impl<T: Eq> Eq for List<T> {}
771 impl<T> Hash for List<T> {
773 fn hash<H: Hasher>(&self, s: &mut H) {
774 (self as *const List<T>).hash(s)
778 impl<T> Deref for List<T> {
781 fn deref(&self) -> &[T] {
786 impl<T> AsRef<[T]> for List<T> {
788 fn as_ref(&self) -> &[T] {
789 unsafe { slice::from_raw_parts(self.data.as_ptr(), self.len) }
793 impl<'a, T> IntoIterator for &'a List<T> {
795 type IntoIter = <&'a [T] as IntoIterator>::IntoIter;
797 fn into_iter(self) -> Self::IntoIter {
802 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx List<Ty<'tcx>> {}
806 pub fn empty<'a>() -> &'a List<T> {
807 #[repr(align(64), C)]
808 struct EmptySlice([u8; 64]);
809 static EMPTY_SLICE: EmptySlice = EmptySlice([0; 64]);
810 assert!(mem::align_of::<T>() <= 64);
811 unsafe { &*(&EMPTY_SLICE as *const _ as *const List<T>) }
815 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
816 pub struct UpvarPath {
817 pub hir_id: hir::HirId,
820 /// Upvars do not get their own `NodeId`. Instead, we use the pair of
821 /// the original var ID (that is, the root variable that is referenced
822 /// by the upvar) and the ID of the closure expression.
823 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, HashStable)]
825 pub var_path: UpvarPath,
826 pub closure_expr_id: LocalDefId,
829 #[derive(Clone, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, HashStable)]
830 pub enum BorrowKind {
831 /// Data must be immutable and is aliasable.
834 /// Data must be immutable but not aliasable. This kind of borrow
835 /// cannot currently be expressed by the user and is used only in
836 /// implicit closure bindings. It is needed when the closure
837 /// is borrowing or mutating a mutable referent, e.g.:
839 /// let x: &mut isize = ...;
840 /// let y = || *x += 5;
842 /// If we were to try to translate this closure into a more explicit
843 /// form, we'd encounter an error with the code as written:
845 /// struct Env { x: & &mut isize }
846 /// let x: &mut isize = ...;
847 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
848 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
850 /// This is then illegal because you cannot mutate a `&mut` found
851 /// in an aliasable location. To solve, you'd have to translate with
852 /// an `&mut` borrow:
854 /// struct Env { x: & &mut isize }
855 /// let x: &mut isize = ...;
856 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
857 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
859 /// Now the assignment to `**env.x` is legal, but creating a
860 /// mutable pointer to `x` is not because `x` is not mutable. We
861 /// could fix this by declaring `x` as `let mut x`. This is ok in
862 /// user code, if awkward, but extra weird for closures, since the
863 /// borrow is hidden.
865 /// So we introduce a "unique imm" borrow -- the referent is
866 /// immutable, but not aliasable. This solves the problem. For
867 /// simplicity, we don't give users the way to express this
868 /// borrow, it's just used when translating closures.
871 /// Data is mutable and not aliasable.
875 /// Information describing the capture of an upvar. This is computed
876 /// during `typeck`, specifically by `regionck`.
877 #[derive(PartialEq, Clone, Debug, Copy, RustcEncodable, RustcDecodable, HashStable)]
878 pub enum UpvarCapture<'tcx> {
879 /// Upvar is captured by value. This is always true when the
880 /// closure is labeled `move`, but can also be true in other cases
881 /// depending on inference.
884 /// Upvar is captured by reference.
885 ByRef(UpvarBorrow<'tcx>),
888 #[derive(PartialEq, Clone, Copy, RustcEncodable, RustcDecodable, HashStable)]
889 pub struct UpvarBorrow<'tcx> {
890 /// The kind of borrow: by-ref upvars have access to shared
891 /// immutable borrows, which are not part of the normal language
893 pub kind: BorrowKind,
895 /// Region of the resulting reference.
896 pub region: ty::Region<'tcx>,
899 pub type UpvarListMap = FxHashMap<DefId, FxIndexMap<hir::HirId, UpvarId>>;
900 pub type UpvarCaptureMap<'tcx> = FxHashMap<UpvarId, UpvarCapture<'tcx>>;
902 #[derive(Clone, Copy, PartialEq, Eq)]
903 pub enum IntVarValue {
905 UintType(ast::UintTy),
908 #[derive(Clone, Copy, PartialEq, Eq)]
909 pub struct FloatVarValue(pub ast::FloatTy);
911 impl ty::EarlyBoundRegion {
912 pub fn to_bound_region(&self) -> ty::BoundRegion {
913 ty::BoundRegion::BrNamed(self.def_id, self.name)
916 /// Does this early bound region have a name? Early bound regions normally
917 /// always have names except when using anonymous lifetimes (`'_`).
918 pub fn has_name(&self) -> bool {
919 self.name != kw::UnderscoreLifetime
923 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
924 pub enum GenericParamDefKind {
928 object_lifetime_default: ObjectLifetimeDefault,
929 synthetic: Option<hir::SyntheticTyParamKind>,
934 #[derive(Clone, RustcEncodable, RustcDecodable, HashStable)]
935 pub struct GenericParamDef {
940 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
941 /// on generic parameter `'a`/`T`, asserts data behind the parameter
942 /// `'a`/`T` won't be accessed during the parent type's `Drop` impl.
943 pub pure_wrt_drop: bool,
945 pub kind: GenericParamDefKind,
948 impl GenericParamDef {
949 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
950 if let GenericParamDefKind::Lifetime = self.kind {
951 ty::EarlyBoundRegion { def_id: self.def_id, index: self.index, name: self.name }
953 bug!("cannot convert a non-lifetime parameter def to an early bound region")
957 pub fn to_bound_region(&self) -> ty::BoundRegion {
958 if let GenericParamDefKind::Lifetime = self.kind {
959 self.to_early_bound_region_data().to_bound_region()
961 bug!("cannot convert a non-lifetime parameter def to an early bound region")
967 pub struct GenericParamCount {
968 pub lifetimes: usize,
973 /// Information about the formal type/lifetime parameters associated
974 /// with an item or method. Analogous to `hir::Generics`.
976 /// The ordering of parameters is the same as in `Subst` (excluding child generics):
977 /// `Self` (optionally), `Lifetime` params..., `Type` params...
978 #[derive(Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
979 pub struct Generics {
980 pub parent: Option<DefId>,
981 pub parent_count: usize,
982 pub params: Vec<GenericParamDef>,
984 /// Reverse map to the `index` field of each `GenericParamDef`.
985 #[stable_hasher(ignore)]
986 pub param_def_id_to_index: FxHashMap<DefId, u32>,
989 pub has_late_bound_regions: Option<Span>,
992 impl<'tcx> Generics {
993 pub fn count(&self) -> usize {
994 self.parent_count + self.params.len()
997 pub fn own_counts(&self) -> GenericParamCount {
998 // We could cache this as a property of `GenericParamCount`, but
999 // the aim is to refactor this away entirely eventually and the
1000 // presence of this method will be a constant reminder.
1001 let mut own_counts: GenericParamCount = Default::default();
1003 for param in &self.params {
1005 GenericParamDefKind::Lifetime => own_counts.lifetimes += 1,
1006 GenericParamDefKind::Type { .. } => own_counts.types += 1,
1007 GenericParamDefKind::Const => own_counts.consts += 1,
1014 pub fn requires_monomorphization(&self, tcx: TyCtxt<'tcx>) -> bool {
1015 if self.own_requires_monomorphization() {
1019 if let Some(parent_def_id) = self.parent {
1020 let parent = tcx.generics_of(parent_def_id);
1021 parent.requires_monomorphization(tcx)
1027 pub fn own_requires_monomorphization(&self) -> bool {
1028 for param in &self.params {
1030 GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true,
1031 GenericParamDefKind::Lifetime => {}
1037 pub fn region_param(
1039 param: &EarlyBoundRegion,
1041 ) -> &'tcx GenericParamDef {
1042 if let Some(index) = param.index.checked_sub(self.parent_count as u32) {
1043 let param = &self.params[index as usize];
1045 GenericParamDefKind::Lifetime => param,
1046 _ => bug!("expected lifetime parameter, but found another generic parameter"),
1049 tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?"))
1050 .region_param(param, tcx)
1054 /// Returns the `GenericParamDef` associated with this `ParamTy`.
1055 pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
1056 if let Some(index) = param.index.checked_sub(self.parent_count as u32) {
1057 let param = &self.params[index as usize];
1059 GenericParamDefKind::Type { .. } => param,
1060 _ => bug!("expected type parameter, but found another generic parameter"),
1063 tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?"))
1064 .type_param(param, tcx)
1068 /// Returns the `ConstParameterDef` associated with this `ParamConst`.
1069 pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef {
1070 if let Some(index) = param.index.checked_sub(self.parent_count as u32) {
1071 let param = &self.params[index as usize];
1073 GenericParamDefKind::Const => param,
1074 _ => bug!("expected const parameter, but found another generic parameter"),
1077 tcx.generics_of(self.parent.expect("parent_count>0 but no parent?"))
1078 .const_param(param, tcx)
1083 /// Bounds on generics.
1084 #[derive(Copy, Clone, Default, Debug, RustcEncodable, RustcDecodable, HashStable)]
1085 pub struct GenericPredicates<'tcx> {
1086 pub parent: Option<DefId>,
1087 pub predicates: &'tcx [(Predicate<'tcx>, Span)],
1090 impl<'tcx> GenericPredicates<'tcx> {
1094 substs: SubstsRef<'tcx>,
1095 ) -> InstantiatedPredicates<'tcx> {
1096 let mut instantiated = InstantiatedPredicates::empty();
1097 self.instantiate_into(tcx, &mut instantiated, substs);
1101 pub fn instantiate_own(
1104 substs: SubstsRef<'tcx>,
1105 ) -> InstantiatedPredicates<'tcx> {
1106 InstantiatedPredicates {
1107 predicates: self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)).collect(),
1108 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
1112 fn instantiate_into(
1115 instantiated: &mut InstantiatedPredicates<'tcx>,
1116 substs: SubstsRef<'tcx>,
1118 if let Some(def_id) = self.parent {
1119 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
1121 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)));
1122 instantiated.spans.extend(self.predicates.iter().map(|(_, sp)| *sp));
1125 pub fn instantiate_identity(&self, tcx: TyCtxt<'tcx>) -> InstantiatedPredicates<'tcx> {
1126 let mut instantiated = InstantiatedPredicates::empty();
1127 self.instantiate_identity_into(tcx, &mut instantiated);
1131 fn instantiate_identity_into(
1134 instantiated: &mut InstantiatedPredicates<'tcx>,
1136 if let Some(def_id) = self.parent {
1137 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
1139 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p));
1140 instantiated.spans.extend(self.predicates.iter().map(|(_, s)| s));
1143 pub fn instantiate_supertrait(
1146 poly_trait_ref: &ty::PolyTraitRef<'tcx>,
1147 ) -> InstantiatedPredicates<'tcx> {
1148 assert_eq!(self.parent, None);
1149 InstantiatedPredicates {
1153 .map(|(pred, _)| pred.subst_supertrait(tcx, poly_trait_ref))
1155 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
1160 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1161 #[derive(HashStable, TypeFoldable)]
1162 pub enum Predicate<'tcx> {
1163 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
1164 /// the `Self` type of the trait reference and `A`, `B`, and `C`
1165 /// would be the type parameters.
1167 /// A trait predicate will have `Constness::Const` if it originates
1168 /// from a bound on a `const fn` without the `?const` opt-out (e.g.,
1169 /// `const fn foobar<Foo: Bar>() {}`).
1170 Trait(PolyTraitPredicate<'tcx>, Constness),
1173 RegionOutlives(PolyRegionOutlivesPredicate<'tcx>),
1176 TypeOutlives(PolyTypeOutlivesPredicate<'tcx>),
1178 /// `where <T as TraitRef>::Name == X`, approximately.
1179 /// See the `ProjectionPredicate` struct for details.
1180 Projection(PolyProjectionPredicate<'tcx>),
1182 /// No syntax: `T` well-formed.
1183 WellFormed(Ty<'tcx>),
1185 /// Trait must be object-safe.
1188 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
1189 /// for some substitutions `...` and `T` being a closure type.
1190 /// Satisfied (or refuted) once we know the closure's kind.
1191 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
1194 Subtype(PolySubtypePredicate<'tcx>),
1196 /// Constant initializer must evaluate successfully.
1197 ConstEvaluatable(DefId, SubstsRef<'tcx>),
1200 /// The crate outlives map is computed during typeck and contains the
1201 /// outlives of every item in the local crate. You should not use it
1202 /// directly, because to do so will make your pass dependent on the
1203 /// HIR of every item in the local crate. Instead, use
1204 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
1206 #[derive(HashStable)]
1207 pub struct CratePredicatesMap<'tcx> {
1208 /// For each struct with outlive bounds, maps to a vector of the
1209 /// predicate of its outlive bounds. If an item has no outlives
1210 /// bounds, it will have no entry.
1211 pub predicates: FxHashMap<DefId, &'tcx [(ty::Predicate<'tcx>, Span)]>,
1214 impl<'tcx> AsRef<Predicate<'tcx>> for Predicate<'tcx> {
1215 fn as_ref(&self) -> &Predicate<'tcx> {
1220 impl<'tcx> Predicate<'tcx> {
1221 /// Performs a substitution suitable for going from a
1222 /// poly-trait-ref to supertraits that must hold if that
1223 /// poly-trait-ref holds. This is slightly different from a normal
1224 /// substitution in terms of what happens with bound regions. See
1225 /// lengthy comment below for details.
1226 pub fn subst_supertrait(
1229 trait_ref: &ty::PolyTraitRef<'tcx>,
1230 ) -> ty::Predicate<'tcx> {
1231 // The interaction between HRTB and supertraits is not entirely
1232 // obvious. Let me walk you (and myself) through an example.
1234 // Let's start with an easy case. Consider two traits:
1236 // trait Foo<'a>: Bar<'a,'a> { }
1237 // trait Bar<'b,'c> { }
1239 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
1240 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
1241 // knew that `Foo<'x>` (for any 'x) then we also know that
1242 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
1243 // normal substitution.
1245 // In terms of why this is sound, the idea is that whenever there
1246 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
1247 // holds. So if there is an impl of `T:Foo<'a>` that applies to
1248 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
1251 // Another example to be careful of is this:
1253 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
1254 // trait Bar1<'b,'c> { }
1256 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
1257 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
1258 // reason is similar to the previous example: any impl of
1259 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
1260 // basically we would want to collapse the bound lifetimes from
1261 // the input (`trait_ref`) and the supertraits.
1263 // To achieve this in practice is fairly straightforward. Let's
1264 // consider the more complicated scenario:
1266 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
1267 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
1268 // where both `'x` and `'b` would have a DB index of 1.
1269 // The substitution from the input trait-ref is therefore going to be
1270 // `'a => 'x` (where `'x` has a DB index of 1).
1271 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1272 // early-bound parameter and `'b' is a late-bound parameter with a
1274 // - If we replace `'a` with `'x` from the input, it too will have
1275 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1276 // just as we wanted.
1278 // There is only one catch. If we just apply the substitution `'a
1279 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1280 // adjust the DB index because we substituting into a binder (it
1281 // tries to be so smart...) resulting in `for<'x> for<'b>
1282 // Bar1<'x,'b>` (we have no syntax for this, so use your
1283 // imagination). Basically the 'x will have DB index of 2 and 'b
1284 // will have DB index of 1. Not quite what we want. So we apply
1285 // the substitution to the *contents* of the trait reference,
1286 // rather than the trait reference itself (put another way, the
1287 // substitution code expects equal binding levels in the values
1288 // from the substitution and the value being substituted into, and
1289 // this trick achieves that).
1291 let substs = &trait_ref.skip_binder().substs;
1293 Predicate::Trait(ref binder, constness) => {
1294 Predicate::Trait(binder.map_bound(|data| data.subst(tcx, substs)), constness)
1296 Predicate::Subtype(ref binder) => {
1297 Predicate::Subtype(binder.map_bound(|data| data.subst(tcx, substs)))
1299 Predicate::RegionOutlives(ref binder) => {
1300 Predicate::RegionOutlives(binder.map_bound(|data| data.subst(tcx, substs)))
1302 Predicate::TypeOutlives(ref binder) => {
1303 Predicate::TypeOutlives(binder.map_bound(|data| data.subst(tcx, substs)))
1305 Predicate::Projection(ref binder) => {
1306 Predicate::Projection(binder.map_bound(|data| data.subst(tcx, substs)))
1308 Predicate::WellFormed(data) => Predicate::WellFormed(data.subst(tcx, substs)),
1309 Predicate::ObjectSafe(trait_def_id) => Predicate::ObjectSafe(trait_def_id),
1310 Predicate::ClosureKind(closure_def_id, closure_substs, kind) => {
1311 Predicate::ClosureKind(closure_def_id, closure_substs.subst(tcx, substs), kind)
1313 Predicate::ConstEvaluatable(def_id, const_substs) => {
1314 Predicate::ConstEvaluatable(def_id, const_substs.subst(tcx, substs))
1320 #[derive(Clone, Copy, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1321 #[derive(HashStable, TypeFoldable)]
1322 pub struct TraitPredicate<'tcx> {
1323 pub trait_ref: TraitRef<'tcx>,
1326 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1328 impl<'tcx> TraitPredicate<'tcx> {
1329 pub fn def_id(&self) -> DefId {
1330 self.trait_ref.def_id
1333 pub fn input_types<'a>(&'a self) -> impl DoubleEndedIterator<Item = Ty<'tcx>> + 'a {
1334 self.trait_ref.input_types()
1337 pub fn self_ty(&self) -> Ty<'tcx> {
1338 self.trait_ref.self_ty()
1342 impl<'tcx> PolyTraitPredicate<'tcx> {
1343 pub fn def_id(&self) -> DefId {
1344 // Ok to skip binder since trait `DefId` does not care about regions.
1345 self.skip_binder().def_id()
1349 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, RustcEncodable, RustcDecodable)]
1350 #[derive(HashStable, TypeFoldable)]
1351 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
1352 pub type PolyOutlivesPredicate<A, B> = ty::Binder<OutlivesPredicate<A, B>>;
1353 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
1354 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1355 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>;
1356 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>;
1358 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, RustcEncodable, RustcDecodable)]
1359 #[derive(HashStable, TypeFoldable)]
1360 pub struct SubtypePredicate<'tcx> {
1361 pub a_is_expected: bool,
1365 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1367 /// This kind of predicate has no *direct* correspondent in the
1368 /// syntax, but it roughly corresponds to the syntactic forms:
1370 /// 1. `T: TraitRef<..., Item = Type>`
1371 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1373 /// In particular, form #1 is "desugared" to the combination of a
1374 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1375 /// predicates. Form #2 is a broader form in that it also permits
1376 /// equality between arbitrary types. Processing an instance of
1377 /// Form #2 eventually yields one of these `ProjectionPredicate`
1378 /// instances to normalize the LHS.
1379 #[derive(Copy, Clone, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable)]
1380 #[derive(HashStable, TypeFoldable)]
1381 pub struct ProjectionPredicate<'tcx> {
1382 pub projection_ty: ProjectionTy<'tcx>,
1386 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1388 impl<'tcx> PolyProjectionPredicate<'tcx> {
1389 /// Returns the `DefId` of the associated item being projected.
1390 pub fn item_def_id(&self) -> DefId {
1391 self.skip_binder().projection_ty.item_def_id
1395 pub fn to_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
1396 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1397 // `self.0.trait_ref` is permitted to have escaping regions.
1398 // This is because here `self` has a `Binder` and so does our
1399 // return value, so we are preserving the number of binding
1401 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1404 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1405 self.map_bound(|predicate| predicate.ty)
1408 /// The `DefId` of the `TraitItem` for the associated type.
1410 /// Note that this is not the `DefId` of the `TraitRef` containing this
1411 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1412 pub fn projection_def_id(&self) -> DefId {
1413 // Ok to skip binder since trait `DefId` does not care about regions.
1414 self.skip_binder().projection_ty.item_def_id
1418 pub trait ToPolyTraitRef<'tcx> {
1419 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1422 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1423 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1424 ty::Binder::dummy(*self)
1428 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1429 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1430 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1434 pub trait ToPredicate<'tcx> {
1435 fn to_predicate(&self) -> Predicate<'tcx>;
1438 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<TraitRef<'tcx>> {
1439 fn to_predicate(&self) -> Predicate<'tcx> {
1440 ty::Predicate::Trait(
1441 ty::Binder::dummy(ty::TraitPredicate { trait_ref: self.value }),
1447 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<&TraitRef<'tcx>> {
1448 fn to_predicate(&self) -> Predicate<'tcx> {
1449 ty::Predicate::Trait(
1450 ty::Binder::dummy(ty::TraitPredicate { trait_ref: self.value.clone() }),
1456 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> {
1457 fn to_predicate(&self) -> Predicate<'tcx> {
1458 ty::Predicate::Trait(self.value.to_poly_trait_predicate(), self.constness)
1462 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<&PolyTraitRef<'tcx>> {
1463 fn to_predicate(&self) -> Predicate<'tcx> {
1464 ty::Predicate::Trait(self.value.to_poly_trait_predicate(), self.constness)
1468 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1469 fn to_predicate(&self) -> Predicate<'tcx> {
1470 Predicate::RegionOutlives(*self)
1474 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1475 fn to_predicate(&self) -> Predicate<'tcx> {
1476 Predicate::TypeOutlives(*self)
1480 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1481 fn to_predicate(&self) -> Predicate<'tcx> {
1482 Predicate::Projection(*self)
1486 // A custom iterator used by `Predicate::walk_tys`.
1487 enum WalkTysIter<'tcx, I, J, K>
1489 I: Iterator<Item = Ty<'tcx>>,
1490 J: Iterator<Item = Ty<'tcx>>,
1491 K: Iterator<Item = Ty<'tcx>>,
1495 Two(Ty<'tcx>, Ty<'tcx>),
1501 impl<'tcx, I, J, K> Iterator for WalkTysIter<'tcx, I, J, K>
1503 I: Iterator<Item = Ty<'tcx>>,
1504 J: Iterator<Item = Ty<'tcx>>,
1505 K: Iterator<Item = Ty<'tcx>>,
1507 type Item = Ty<'tcx>;
1509 fn next(&mut self) -> Option<Ty<'tcx>> {
1511 WalkTysIter::None => None,
1512 WalkTysIter::One(item) => {
1513 *self = WalkTysIter::None;
1516 WalkTysIter::Two(item1, item2) => {
1517 *self = WalkTysIter::One(item2);
1520 WalkTysIter::Types(ref mut iter) => iter.next(),
1521 WalkTysIter::InputTypes(ref mut iter) => iter.next(),
1522 WalkTysIter::ProjectionTypes(ref mut iter) => iter.next(),
1527 impl<'tcx> Predicate<'tcx> {
1528 /// Iterates over the types in this predicate. Note that in all
1529 /// cases this is skipping over a binder, so late-bound regions
1530 /// with depth 0 are bound by the predicate.
1531 pub fn walk_tys(&'a self) -> impl Iterator<Item = Ty<'tcx>> + 'a {
1533 ty::Predicate::Trait(ref data, _) => {
1534 WalkTysIter::InputTypes(data.skip_binder().input_types())
1536 ty::Predicate::Subtype(binder) => {
1537 let SubtypePredicate { a, b, a_is_expected: _ } = binder.skip_binder();
1538 WalkTysIter::Two(a, b)
1540 ty::Predicate::TypeOutlives(binder) => WalkTysIter::One(binder.skip_binder().0),
1541 ty::Predicate::RegionOutlives(..) => WalkTysIter::None,
1542 ty::Predicate::Projection(ref data) => {
1543 let inner = data.skip_binder();
1544 WalkTysIter::ProjectionTypes(
1545 inner.projection_ty.substs.types().chain(Some(inner.ty)),
1548 ty::Predicate::WellFormed(data) => WalkTysIter::One(data),
1549 ty::Predicate::ObjectSafe(_trait_def_id) => WalkTysIter::None,
1550 ty::Predicate::ClosureKind(_closure_def_id, closure_substs, _kind) => {
1551 WalkTysIter::Types(closure_substs.types())
1553 ty::Predicate::ConstEvaluatable(_, substs) => WalkTysIter::Types(substs.types()),
1557 pub fn to_opt_poly_trait_ref(&self) -> Option<PolyTraitRef<'tcx>> {
1559 Predicate::Trait(ref t, _) => Some(t.to_poly_trait_ref()),
1560 Predicate::Projection(..)
1561 | Predicate::Subtype(..)
1562 | Predicate::RegionOutlives(..)
1563 | Predicate::WellFormed(..)
1564 | Predicate::ObjectSafe(..)
1565 | Predicate::ClosureKind(..)
1566 | Predicate::TypeOutlives(..)
1567 | Predicate::ConstEvaluatable(..) => None,
1571 pub fn to_opt_type_outlives(&self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1573 Predicate::TypeOutlives(data) => Some(data),
1574 Predicate::Trait(..)
1575 | Predicate::Projection(..)
1576 | Predicate::Subtype(..)
1577 | Predicate::RegionOutlives(..)
1578 | Predicate::WellFormed(..)
1579 | Predicate::ObjectSafe(..)
1580 | Predicate::ClosureKind(..)
1581 | Predicate::ConstEvaluatable(..) => None,
1586 /// Represents the bounds declared on a particular set of type
1587 /// parameters. Should eventually be generalized into a flag list of
1588 /// where-clauses. You can obtain a `InstantiatedPredicates` list from a
1589 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1590 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1591 /// the `GenericPredicates` are expressed in terms of the bound type
1592 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1593 /// represented a set of bounds for some particular instantiation,
1594 /// meaning that the generic parameters have been substituted with
1599 /// struct Foo<T, U: Bar<T>> { ... }
1601 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1602 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1603 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1604 /// [usize:Bar<isize>]]`.
1605 #[derive(Clone, Debug, TypeFoldable)]
1606 pub struct InstantiatedPredicates<'tcx> {
1607 pub predicates: Vec<Predicate<'tcx>>,
1608 pub spans: Vec<Span>,
1611 impl<'tcx> InstantiatedPredicates<'tcx> {
1612 pub fn empty() -> InstantiatedPredicates<'tcx> {
1613 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1616 pub fn is_empty(&self) -> bool {
1617 self.predicates.is_empty()
1621 rustc_index::newtype_index! {
1622 /// "Universes" are used during type- and trait-checking in the
1623 /// presence of `for<..>` binders to control what sets of names are
1624 /// visible. Universes are arranged into a tree: the root universe
1625 /// contains names that are always visible. Each child then adds a new
1626 /// set of names that are visible, in addition to those of its parent.
1627 /// We say that the child universe "extends" the parent universe with
1630 /// To make this more concrete, consider this program:
1634 /// fn bar<T>(x: T) {
1635 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1639 /// The struct name `Foo` is in the root universe U0. But the type
1640 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1641 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1642 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1643 /// region `'a` is in a universe U2 that extends U1, because we can
1644 /// name it inside the fn type but not outside.
1646 /// Universes are used to do type- and trait-checking around these
1647 /// "forall" binders (also called **universal quantification**). The
1648 /// idea is that when, in the body of `bar`, we refer to `T` as a
1649 /// type, we aren't referring to any type in particular, but rather a
1650 /// kind of "fresh" type that is distinct from all other types we have
1651 /// actually declared. This is called a **placeholder** type, and we
1652 /// use universes to talk about this. In other words, a type name in
1653 /// universe 0 always corresponds to some "ground" type that the user
1654 /// declared, but a type name in a non-zero universe is a placeholder
1655 /// type -- an idealized representative of "types in general" that we
1656 /// use for checking generic functions.
1657 pub struct UniverseIndex {
1659 DEBUG_FORMAT = "U{}",
1663 impl UniverseIndex {
1664 pub const ROOT: UniverseIndex = UniverseIndex::from_u32_const(0);
1666 /// Returns the "next" universe index in order -- this new index
1667 /// is considered to extend all previous universes. This
1668 /// corresponds to entering a `forall` quantifier. So, for
1669 /// example, suppose we have this type in universe `U`:
1672 /// for<'a> fn(&'a u32)
1675 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1676 /// new universe that extends `U` -- in this new universe, we can
1677 /// name the region `'a`, but that region was not nameable from
1678 /// `U` because it was not in scope there.
1679 pub fn next_universe(self) -> UniverseIndex {
1680 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1683 /// Returns `true` if `self` can name a name from `other` -- in other words,
1684 /// if the set of names in `self` is a superset of those in
1685 /// `other` (`self >= other`).
1686 pub fn can_name(self, other: UniverseIndex) -> bool {
1687 self.private >= other.private
1690 /// Returns `true` if `self` cannot name some names from `other` -- in other
1691 /// words, if the set of names in `self` is a strict subset of
1692 /// those in `other` (`self < other`).
1693 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1694 self.private < other.private
1698 /// The "placeholder index" fully defines a placeholder region.
1699 /// Placeholder regions are identified by both a **universe** as well
1700 /// as a "bound-region" within that universe. The `bound_region` is
1701 /// basically a name -- distinct bound regions within the same
1702 /// universe are just two regions with an unknown relationship to one
1704 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, RustcEncodable, RustcDecodable, PartialOrd, Ord)]
1705 pub struct Placeholder<T> {
1706 pub universe: UniverseIndex,
1710 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1712 T: HashStable<StableHashingContext<'a>>,
1714 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1715 self.universe.hash_stable(hcx, hasher);
1716 self.name.hash_stable(hcx, hasher);
1720 pub type PlaceholderRegion = Placeholder<BoundRegion>;
1722 pub type PlaceholderType = Placeholder<BoundVar>;
1724 pub type PlaceholderConst = Placeholder<BoundVar>;
1726 /// When type checking, we use the `ParamEnv` to track
1727 /// details about the set of where-clauses that are in scope at this
1728 /// particular point.
1729 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TypeFoldable)]
1730 pub struct ParamEnv<'tcx> {
1731 /// `Obligation`s that the caller must satisfy. This is basically
1732 /// the set of bounds on the in-scope type parameters, translated
1733 /// into `Obligation`s, and elaborated and normalized.
1734 pub caller_bounds: &'tcx List<ty::Predicate<'tcx>>,
1736 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1737 /// want `Reveal::All` -- note that this is always paired with an
1738 /// empty environment. To get that, use `ParamEnv::reveal()`.
1739 pub reveal: traits::Reveal,
1741 /// If this `ParamEnv` comes from a call to `tcx.param_env(def_id)`,
1742 /// register that `def_id` (useful for transitioning to the chalk trait
1744 pub def_id: Option<DefId>,
1747 impl<'tcx> ParamEnv<'tcx> {
1748 /// Construct a trait environment suitable for contexts where
1749 /// there are no where-clauses in scope. Hidden types (like `impl
1750 /// Trait`) are left hidden, so this is suitable for ordinary
1753 pub fn empty() -> Self {
1754 Self::new(List::empty(), Reveal::UserFacing, None)
1757 /// Construct a trait environment with no where-clauses in scope
1758 /// where the values of all `impl Trait` and other hidden types
1759 /// are revealed. This is suitable for monomorphized, post-typeck
1760 /// environments like codegen or doing optimizations.
1762 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1763 /// or invoke `param_env.with_reveal_all()`.
1765 pub fn reveal_all() -> Self {
1766 Self::new(List::empty(), Reveal::All, None)
1769 /// Construct a trait environment with the given set of predicates.
1772 caller_bounds: &'tcx List<ty::Predicate<'tcx>>,
1774 def_id: Option<DefId>,
1776 ty::ParamEnv { caller_bounds, reveal, def_id }
1779 /// Returns a new parameter environment with the same clauses, but
1780 /// which "reveals" the true results of projections in all cases
1781 /// (even for associated types that are specializable). This is
1782 /// the desired behavior during codegen and certain other special
1783 /// contexts; normally though we want to use `Reveal::UserFacing`,
1784 /// which is the default.
1785 pub fn with_reveal_all(self) -> Self {
1786 ty::ParamEnv { reveal: Reveal::All, ..self }
1789 /// Returns this same environment but with no caller bounds.
1790 pub fn without_caller_bounds(self) -> Self {
1791 ty::ParamEnv { caller_bounds: List::empty(), ..self }
1794 /// Creates a suitable environment in which to perform trait
1795 /// queries on the given value. When type-checking, this is simply
1796 /// the pair of the environment plus value. But when reveal is set to
1797 /// All, then if `value` does not reference any type parameters, we will
1798 /// pair it with the empty environment. This improves caching and is generally
1801 /// N.B., we preserve the environment when type-checking because it
1802 /// is possible for the user to have wacky where-clauses like
1803 /// `where Box<u32>: Copy`, which are clearly never
1804 /// satisfiable. We generally want to behave as if they were true,
1805 /// although the surrounding function is never reachable.
1806 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1808 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1811 if value.has_placeholders() || value.needs_infer() || value.has_param_types() {
1812 ParamEnvAnd { param_env: self, value }
1814 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1821 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1822 pub struct ConstnessAnd<T> {
1823 pub constness: Constness,
1827 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate()` to ensure that
1828 // the constness of trait bounds is being propagated correctly.
1829 pub trait WithConstness: Sized {
1831 fn with_constness(self, constness: Constness) -> ConstnessAnd<Self> {
1832 ConstnessAnd { constness, value: self }
1836 fn with_const(self) -> ConstnessAnd<Self> {
1837 self.with_constness(Constness::Const)
1841 fn without_const(self) -> ConstnessAnd<Self> {
1842 self.with_constness(Constness::NotConst)
1846 impl<T> WithConstness for T {}
1848 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1849 pub struct ParamEnvAnd<'tcx, T> {
1850 pub param_env: ParamEnv<'tcx>,
1854 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1855 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1856 (self.param_env, self.value)
1860 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1862 T: HashStable<StableHashingContext<'a>>,
1864 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1865 let ParamEnvAnd { ref param_env, ref value } = *self;
1867 param_env.hash_stable(hcx, hasher);
1868 value.hash_stable(hcx, hasher);
1872 #[derive(Copy, Clone, Debug, HashStable)]
1873 pub struct Destructor {
1874 /// The `DefId` of the destructor method
1879 #[derive(HashStable)]
1880 pub struct AdtFlags: u32 {
1881 const NO_ADT_FLAGS = 0;
1882 /// Indicates whether the ADT is an enum.
1883 const IS_ENUM = 1 << 0;
1884 /// Indicates whether the ADT is a union.
1885 const IS_UNION = 1 << 1;
1886 /// Indicates whether the ADT is a struct.
1887 const IS_STRUCT = 1 << 2;
1888 /// Indicates whether the ADT is a struct and has a constructor.
1889 const HAS_CTOR = 1 << 3;
1890 /// Indicates whether the type is `PhantomData`.
1891 const IS_PHANTOM_DATA = 1 << 4;
1892 /// Indicates whether the type has a `#[fundamental]` attribute.
1893 const IS_FUNDAMENTAL = 1 << 5;
1894 /// Indicates whether the type is `Box`.
1895 const IS_BOX = 1 << 6;
1896 /// Indicates whether the type is `ManuallyDrop`.
1897 const IS_MANUALLY_DROP = 1 << 7;
1898 // FIXME(matthewjasper) replace these with diagnostic items
1899 /// Indicates whether the type is an `Arc`.
1900 const IS_ARC = 1 << 8;
1901 /// Indicates whether the type is an `Rc`.
1902 const IS_RC = 1 << 9;
1903 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
1904 /// (i.e., this flag is never set unless this ADT is an enum).
1905 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 10;
1910 #[derive(HashStable)]
1911 pub struct VariantFlags: u32 {
1912 const NO_VARIANT_FLAGS = 0;
1913 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1914 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1918 /// Definition of a variant -- a struct's fields or a enum variant.
1919 #[derive(Debug, HashStable)]
1920 pub struct VariantDef {
1921 /// `DefId` that identifies the variant itself.
1922 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1924 /// `DefId` that identifies the variant's constructor.
1925 /// If this variant is a struct variant, then this is `None`.
1926 pub ctor_def_id: Option<DefId>,
1927 /// Variant or struct name.
1928 #[stable_hasher(project(name))]
1930 /// Discriminant of this variant.
1931 pub discr: VariantDiscr,
1932 /// Fields of this variant.
1933 pub fields: Vec<FieldDef>,
1934 /// Type of constructor of variant.
1935 pub ctor_kind: CtorKind,
1936 /// Flags of the variant (e.g. is field list non-exhaustive)?
1937 flags: VariantFlags,
1938 /// Variant is obtained as part of recovering from a syntactic error.
1939 /// May be incomplete or bogus.
1940 pub recovered: bool,
1943 impl<'tcx> VariantDef {
1944 /// Creates a new `VariantDef`.
1946 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1947 /// represents an enum variant).
1949 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1950 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1952 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1953 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1954 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1955 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1956 /// built-in trait), and we do not want to load attributes twice.
1958 /// If someone speeds up attribute loading to not be a performance concern, they can
1959 /// remove this hack and use the constructor `DefId` everywhere.
1963 variant_did: Option<DefId>,
1964 ctor_def_id: Option<DefId>,
1965 discr: VariantDiscr,
1966 fields: Vec<FieldDef>,
1967 ctor_kind: CtorKind,
1973 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1974 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1975 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1978 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1979 if adt_kind == AdtKind::Struct && tcx.has_attr(parent_did, sym::non_exhaustive) {
1980 debug!("found non-exhaustive field list for {:?}", parent_did);
1981 flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1982 } else if let Some(variant_did) = variant_did {
1983 if tcx.has_attr(variant_did, sym::non_exhaustive) {
1984 debug!("found non-exhaustive field list for {:?}", variant_did);
1985 flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1990 def_id: variant_did.unwrap_or(parent_did),
2001 /// Is this field list non-exhaustive?
2003 pub fn is_field_list_non_exhaustive(&self) -> bool {
2004 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
2008 #[derive(Copy, Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
2009 pub enum VariantDiscr {
2010 /// Explicit value for this variant, i.e., `X = 123`.
2011 /// The `DefId` corresponds to the embedded constant.
2014 /// The previous variant's discriminant plus one.
2015 /// For efficiency reasons, the distance from the
2016 /// last `Explicit` discriminant is being stored,
2017 /// or `0` for the first variant, if it has none.
2021 #[derive(Debug, HashStable)]
2022 pub struct FieldDef {
2024 #[stable_hasher(project(name))]
2026 pub vis: Visibility,
2029 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
2031 /// These are all interned (by `intern_adt_def`) into the `adt_defs` table.
2033 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
2034 /// This is slightly wrong because `union`s are not ADTs.
2035 /// Moreover, Rust only allows recursive data types through indirection.
2037 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
2039 /// The `DefId` of the struct, enum or union item.
2041 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
2042 pub variants: IndexVec<self::layout::VariantIdx, VariantDef>,
2043 /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
2045 /// Repr options provided by the user.
2046 pub repr: ReprOptions,
2049 impl PartialOrd for AdtDef {
2050 fn partial_cmp(&self, other: &AdtDef) -> Option<Ordering> {
2051 Some(self.cmp(&other))
2055 /// There should be only one AdtDef for each `did`, therefore
2056 /// it is fine to implement `Ord` only based on `did`.
2057 impl Ord for AdtDef {
2058 fn cmp(&self, other: &AdtDef) -> Ordering {
2059 self.did.cmp(&other.did)
2063 impl PartialEq for AdtDef {
2064 // `AdtDef`s are always interned, and this is part of `TyS` equality.
2066 fn eq(&self, other: &Self) -> bool {
2067 ptr::eq(self, other)
2071 impl Eq for AdtDef {}
2073 impl Hash for AdtDef {
2075 fn hash<H: Hasher>(&self, s: &mut H) {
2076 (self as *const AdtDef).hash(s)
2080 impl<'tcx> rustc_serialize::UseSpecializedEncodable for &'tcx AdtDef {
2081 fn default_encode<S: Encoder>(&self, s: &mut S) -> Result<(), S::Error> {
2086 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx AdtDef {}
2088 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
2089 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
2091 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default();
2094 let hash: Fingerprint = CACHE.with(|cache| {
2095 let addr = self as *const AdtDef as usize;
2096 *cache.borrow_mut().entry(addr).or_insert_with(|| {
2097 let ty::AdtDef { did, ref variants, ref flags, ref repr } = *self;
2099 let mut hasher = StableHasher::new();
2100 did.hash_stable(hcx, &mut hasher);
2101 variants.hash_stable(hcx, &mut hasher);
2102 flags.hash_stable(hcx, &mut hasher);
2103 repr.hash_stable(hcx, &mut hasher);
2109 hash.hash_stable(hcx, hasher);
2113 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
2120 impl Into<DataTypeKind> for AdtKind {
2121 fn into(self) -> DataTypeKind {
2123 AdtKind::Struct => DataTypeKind::Struct,
2124 AdtKind::Union => DataTypeKind::Union,
2125 AdtKind::Enum => DataTypeKind::Enum,
2131 #[derive(RustcEncodable, RustcDecodable, Default, HashStable)]
2132 pub struct ReprFlags: u8 {
2133 const IS_C = 1 << 0;
2134 const IS_SIMD = 1 << 1;
2135 const IS_TRANSPARENT = 1 << 2;
2136 // Internal only for now. If true, don't reorder fields.
2137 const IS_LINEAR = 1 << 3;
2138 // If true, don't expose any niche to type's context.
2139 const HIDE_NICHE = 1 << 4;
2140 // Any of these flags being set prevent field reordering optimisation.
2141 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
2142 ReprFlags::IS_SIMD.bits |
2143 ReprFlags::IS_LINEAR.bits;
2147 /// Represents the repr options provided by the user,
2148 #[derive(Copy, Clone, Debug, Eq, PartialEq, RustcEncodable, RustcDecodable, Default, HashStable)]
2149 pub struct ReprOptions {
2150 pub int: Option<attr::IntType>,
2151 pub align: Option<Align>,
2152 pub pack: Option<Align>,
2153 pub flags: ReprFlags,
2157 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
2158 let mut flags = ReprFlags::empty();
2159 let mut size = None;
2160 let mut max_align: Option<Align> = None;
2161 let mut min_pack: Option<Align> = None;
2162 for attr in tcx.get_attrs(did).iter() {
2163 for r in attr::find_repr_attrs(&tcx.sess.parse_sess, attr) {
2164 flags.insert(match r {
2165 attr::ReprC => ReprFlags::IS_C,
2166 attr::ReprPacked(pack) => {
2167 let pack = Align::from_bytes(pack as u64).unwrap();
2168 min_pack = Some(if let Some(min_pack) = min_pack {
2175 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2176 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
2177 attr::ReprSimd => ReprFlags::IS_SIMD,
2178 attr::ReprInt(i) => {
2182 attr::ReprAlign(align) => {
2183 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2190 // This is here instead of layout because the choice must make it into metadata.
2191 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2192 flags.insert(ReprFlags::IS_LINEAR);
2194 ReprOptions { int: size, align: max_align, pack: min_pack, flags: flags }
2198 pub fn simd(&self) -> bool {
2199 self.flags.contains(ReprFlags::IS_SIMD)
2202 pub fn c(&self) -> bool {
2203 self.flags.contains(ReprFlags::IS_C)
2206 pub fn packed(&self) -> bool {
2210 pub fn transparent(&self) -> bool {
2211 self.flags.contains(ReprFlags::IS_TRANSPARENT)
2214 pub fn linear(&self) -> bool {
2215 self.flags.contains(ReprFlags::IS_LINEAR)
2218 pub fn hide_niche(&self) -> bool {
2219 self.flags.contains(ReprFlags::HIDE_NICHE)
2222 pub fn discr_type(&self) -> attr::IntType {
2223 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2226 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2227 /// layout" optimizations, such as representing `Foo<&T>` as a
2229 pub fn inhibit_enum_layout_opt(&self) -> bool {
2230 self.c() || self.int.is_some()
2233 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2234 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2235 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2236 if let Some(pack) = self.pack {
2237 if pack.bytes() == 1 {
2241 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2244 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2245 pub fn inhibit_union_abi_opt(&self) -> bool {
2251 /// Creates a new `AdtDef`.
2256 variants: IndexVec<VariantIdx, VariantDef>,
2259 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
2260 let mut flags = AdtFlags::NO_ADT_FLAGS;
2262 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
2263 debug!("found non-exhaustive variant list for {:?}", did);
2264 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
2267 flags |= match kind {
2268 AdtKind::Enum => AdtFlags::IS_ENUM,
2269 AdtKind::Union => AdtFlags::IS_UNION,
2270 AdtKind::Struct => AdtFlags::IS_STRUCT,
2273 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
2274 flags |= AdtFlags::HAS_CTOR;
2277 let attrs = tcx.get_attrs(did);
2278 if attr::contains_name(&attrs, sym::fundamental) {
2279 flags |= AdtFlags::IS_FUNDAMENTAL;
2281 if Some(did) == tcx.lang_items().phantom_data() {
2282 flags |= AdtFlags::IS_PHANTOM_DATA;
2284 if Some(did) == tcx.lang_items().owned_box() {
2285 flags |= AdtFlags::IS_BOX;
2287 if Some(did) == tcx.lang_items().manually_drop() {
2288 flags |= AdtFlags::IS_MANUALLY_DROP;
2290 if Some(did) == tcx.lang_items().arc() {
2291 flags |= AdtFlags::IS_ARC;
2293 if Some(did) == tcx.lang_items().rc() {
2294 flags |= AdtFlags::IS_RC;
2297 AdtDef { did, variants, flags, repr }
2300 /// Returns `true` if this is a struct.
2302 pub fn is_struct(&self) -> bool {
2303 self.flags.contains(AdtFlags::IS_STRUCT)
2306 /// Returns `true` if this is a union.
2308 pub fn is_union(&self) -> bool {
2309 self.flags.contains(AdtFlags::IS_UNION)
2312 /// Returns `true` if this is a enum.
2314 pub fn is_enum(&self) -> bool {
2315 self.flags.contains(AdtFlags::IS_ENUM)
2318 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
2320 pub fn is_variant_list_non_exhaustive(&self) -> bool {
2321 self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
2324 /// Returns the kind of the ADT.
2326 pub fn adt_kind(&self) -> AdtKind {
2329 } else if self.is_union() {
2336 /// Returns a description of this abstract data type.
2337 pub fn descr(&self) -> &'static str {
2338 match self.adt_kind() {
2339 AdtKind::Struct => "struct",
2340 AdtKind::Union => "union",
2341 AdtKind::Enum => "enum",
2345 /// Returns a description of a variant of this abstract data type.
2347 pub fn variant_descr(&self) -> &'static str {
2348 match self.adt_kind() {
2349 AdtKind::Struct => "struct",
2350 AdtKind::Union => "union",
2351 AdtKind::Enum => "variant",
2355 /// If this function returns `true`, it implies that `is_struct` must return `true`.
2357 pub fn has_ctor(&self) -> bool {
2358 self.flags.contains(AdtFlags::HAS_CTOR)
2361 /// Returns `true` if this type is `#[fundamental]` for the purposes
2362 /// of coherence checking.
2364 pub fn is_fundamental(&self) -> bool {
2365 self.flags.contains(AdtFlags::IS_FUNDAMENTAL)
2368 /// Returns `true` if this is `PhantomData<T>`.
2370 pub fn is_phantom_data(&self) -> bool {
2371 self.flags.contains(AdtFlags::IS_PHANTOM_DATA)
2374 /// Returns `true` if this is `Arc<T>`.
2375 pub fn is_arc(&self) -> bool {
2376 self.flags.contains(AdtFlags::IS_ARC)
2379 /// Returns `true` if this is `Rc<T>`.
2380 pub fn is_rc(&self) -> bool {
2381 self.flags.contains(AdtFlags::IS_RC)
2384 /// Returns `true` if this is Box<T>.
2386 pub fn is_box(&self) -> bool {
2387 self.flags.contains(AdtFlags::IS_BOX)
2390 /// Returns `true` if this is `ManuallyDrop<T>`.
2392 pub fn is_manually_drop(&self) -> bool {
2393 self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
2396 /// Returns `true` if this type has a destructor.
2397 pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
2398 self.destructor(tcx).is_some()
2401 /// Asserts this is a struct or union and returns its unique variant.
2402 pub fn non_enum_variant(&self) -> &VariantDef {
2403 assert!(self.is_struct() || self.is_union());
2404 &self.variants[VariantIdx::new(0)]
2408 pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
2409 tcx.predicates_of(self.did)
2412 /// Returns an iterator over all fields contained
2415 pub fn all_fields(&self) -> impl Iterator<Item = &FieldDef> + Clone {
2416 self.variants.iter().flat_map(|v| v.fields.iter())
2419 pub fn is_payloadfree(&self) -> bool {
2420 !self.variants.is_empty() && self.variants.iter().all(|v| v.fields.is_empty())
2423 /// Return a `VariantDef` given a variant id.
2424 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
2425 self.variants.iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
2428 /// Return a `VariantDef` given a constructor id.
2429 pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
2432 .find(|v| v.ctor_def_id == Some(cid))
2433 .expect("variant_with_ctor_id: unknown variant")
2436 /// Return the index of `VariantDef` given a variant id.
2437 pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
2440 .find(|(_, v)| v.def_id == vid)
2441 .expect("variant_index_with_id: unknown variant")
2445 /// Return the index of `VariantDef` given a constructor id.
2446 pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
2449 .find(|(_, v)| v.ctor_def_id == Some(cid))
2450 .expect("variant_index_with_ctor_id: unknown variant")
2454 pub fn variant_of_res(&self, res: Res) -> &VariantDef {
2456 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
2457 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
2458 Res::Def(DefKind::Struct, _)
2459 | Res::Def(DefKind::Union, _)
2460 | Res::Def(DefKind::TyAlias, _)
2461 | Res::Def(DefKind::AssocTy, _)
2463 | Res::SelfCtor(..) => self.non_enum_variant(),
2464 _ => bug!("unexpected res {:?} in variant_of_res", res),
2469 pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
2470 let param_env = tcx.param_env(expr_did);
2471 let repr_type = self.repr.discr_type();
2472 match tcx.const_eval_poly(expr_did) {
2474 let ty = repr_type.to_ty(tcx);
2475 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
2476 trace!("discriminants: {} ({:?})", b, repr_type);
2477 Some(Discr { val: b, ty })
2479 info!("invalid enum discriminant: {:#?}", val);
2480 crate::mir::interpret::struct_error(
2481 tcx.at(tcx.def_span(expr_did)),
2482 "constant evaluation of enum discriminant resulted in non-integer",
2488 Err(ErrorHandled::Reported) => {
2489 if !expr_did.is_local() {
2491 tcx.def_span(expr_did),
2492 "variant discriminant evaluation succeeded \
2493 in its crate but failed locally"
2498 Err(ErrorHandled::TooGeneric) => {
2499 span_bug!(tcx.def_span(expr_did), "enum discriminant depends on generic arguments",)
2505 pub fn discriminants(
2508 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
2509 let repr_type = self.repr.discr_type();
2510 let initial = repr_type.initial_discriminant(tcx);
2511 let mut prev_discr = None::<Discr<'tcx>>;
2512 self.variants.iter_enumerated().map(move |(i, v)| {
2513 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
2514 if let VariantDiscr::Explicit(expr_did) = v.discr {
2515 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
2519 prev_discr = Some(discr);
2526 pub fn variant_range(&self) -> Range<VariantIdx> {
2527 VariantIdx::new(0)..VariantIdx::new(self.variants.len())
2530 /// Computes the discriminant value used by a specific variant.
2531 /// Unlike `discriminants`, this is (amortized) constant-time,
2532 /// only doing at most one query for evaluating an explicit
2533 /// discriminant (the last one before the requested variant),
2534 /// assuming there are no constant-evaluation errors there.
2536 pub fn discriminant_for_variant(
2539 variant_index: VariantIdx,
2541 let (val, offset) = self.discriminant_def_for_variant(variant_index);
2542 let explicit_value = val
2543 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
2544 .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx));
2545 explicit_value.checked_add(tcx, offset as u128).0
2548 /// Yields a `DefId` for the discriminant and an offset to add to it
2549 /// Alternatively, if there is no explicit discriminant, returns the
2550 /// inferred discriminant directly.
2551 pub fn discriminant_def_for_variant(&self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
2552 let mut explicit_index = variant_index.as_u32();
2555 match self.variants[VariantIdx::from_u32(explicit_index)].discr {
2556 ty::VariantDiscr::Relative(0) => {
2560 ty::VariantDiscr::Relative(distance) => {
2561 explicit_index -= distance;
2563 ty::VariantDiscr::Explicit(did) => {
2564 expr_did = Some(did);
2569 (expr_did, variant_index.as_u32() - explicit_index)
2572 pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
2573 tcx.adt_destructor(self.did)
2576 /// Returns a list of types such that `Self: Sized` if and only
2577 /// if that type is `Sized`, or `TyErr` if this type is recursive.
2579 /// Oddly enough, checking that the sized-constraint is `Sized` is
2580 /// actually more expressive than checking all members:
2581 /// the `Sized` trait is inductive, so an associated type that references
2582 /// `Self` would prevent its containing ADT from being `Sized`.
2584 /// Due to normalization being eager, this applies even if
2585 /// the associated type is behind a pointer (e.g., issue #31299).
2586 pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] {
2587 tcx.adt_sized_constraint(self.did).0
2591 impl<'tcx> FieldDef {
2592 /// Returns the type of this field. The `subst` is typically obtained
2593 /// via the second field of `TyKind::AdtDef`.
2594 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2595 tcx.type_of(self.did).subst(tcx, subst)
2599 /// Represents the various closure traits in the language. This
2600 /// will determine the type of the environment (`self`, in the
2601 /// desugaring) argument that the closure expects.
2603 /// You can get the environment type of a closure using
2604 /// `tcx.closure_env_ty()`.
2618 pub enum ClosureKind {
2619 // Warning: Ordering is significant here! The ordering is chosen
2620 // because the trait Fn is a subtrait of FnMut and so in turn, and
2621 // hence we order it so that Fn < FnMut < FnOnce.
2627 impl<'tcx> ClosureKind {
2628 // This is the initial value used when doing upvar inference.
2629 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2631 pub fn trait_did(&self, tcx: TyCtxt<'tcx>) -> DefId {
2633 ClosureKind::Fn => tcx.require_lang_item(FnTraitLangItem, None),
2634 ClosureKind::FnMut => tcx.require_lang_item(FnMutTraitLangItem, None),
2635 ClosureKind::FnOnce => tcx.require_lang_item(FnOnceTraitLangItem, None),
2639 /// Returns `true` if this a type that impls this closure kind
2640 /// must also implement `other`.
2641 pub fn extends(self, other: ty::ClosureKind) -> bool {
2642 match (self, other) {
2643 (ClosureKind::Fn, ClosureKind::Fn) => true,
2644 (ClosureKind::Fn, ClosureKind::FnMut) => true,
2645 (ClosureKind::Fn, ClosureKind::FnOnce) => true,
2646 (ClosureKind::FnMut, ClosureKind::FnMut) => true,
2647 (ClosureKind::FnMut, ClosureKind::FnOnce) => true,
2648 (ClosureKind::FnOnce, ClosureKind::FnOnce) => true,
2653 /// Returns the representative scalar type for this closure kind.
2654 /// See `TyS::to_opt_closure_kind` for more details.
2655 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2657 ty::ClosureKind::Fn => tcx.types.i8,
2658 ty::ClosureKind::FnMut => tcx.types.i16,
2659 ty::ClosureKind::FnOnce => tcx.types.i32,
2664 impl<'tcx> TyS<'tcx> {
2665 /// Iterator that walks `self` and any types reachable from
2666 /// `self`, in depth-first order. Note that just walks the types
2667 /// that appear in `self`, it does not descend into the fields of
2668 /// structs or variants. For example:
2671 /// isize => { isize }
2672 /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
2673 /// [isize] => { [isize], isize }
2675 pub fn walk(&'tcx self) -> TypeWalker<'tcx> {
2676 TypeWalker::new(self)
2679 /// Iterator that walks the immediate children of `self`. Hence
2680 /// `Foo<Bar<i32>, u32>` yields the sequence `[Bar<i32>, u32]`
2681 /// (but not `i32`, like `walk`).
2682 pub fn walk_shallow(&'tcx self) -> smallvec::IntoIter<walk::TypeWalkerArray<'tcx>> {
2683 walk::walk_shallow(self)
2686 /// Walks `ty` and any types appearing within `ty`, invoking the
2687 /// callback `f` on each type. If the callback returns `false`, then the
2688 /// children of the current type are ignored.
2690 /// Note: prefer `ty.walk()` where possible.
2691 pub fn maybe_walk<F>(&'tcx self, mut f: F)
2693 F: FnMut(Ty<'tcx>) -> bool,
2695 let mut walker = self.walk();
2696 while let Some(ty) = walker.next() {
2698 walker.skip_current_subtree();
2705 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2707 hir::Mutability::Mut => MutBorrow,
2708 hir::Mutability::Not => ImmBorrow,
2712 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2713 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2714 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2716 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2718 MutBorrow => hir::Mutability::Mut,
2719 ImmBorrow => hir::Mutability::Not,
2721 // We have no type corresponding to a unique imm borrow, so
2722 // use `&mut`. It gives all the capabilities of an `&uniq`
2723 // and hence is a safe "over approximation".
2724 UniqueImmBorrow => hir::Mutability::Mut,
2728 pub fn to_user_str(&self) -> &'static str {
2730 MutBorrow => "mutable",
2731 ImmBorrow => "immutable",
2732 UniqueImmBorrow => "uniquely immutable",
2737 #[derive(Debug, Clone)]
2738 pub enum Attributes<'tcx> {
2739 Owned(Lrc<[ast::Attribute]>),
2740 Borrowed(&'tcx [ast::Attribute]),
2743 impl<'tcx> ::std::ops::Deref for Attributes<'tcx> {
2744 type Target = [ast::Attribute];
2746 fn deref(&self) -> &[ast::Attribute] {
2748 &Attributes::Owned(ref data) => &data,
2749 &Attributes::Borrowed(data) => data,
2754 #[derive(Debug, PartialEq, Eq)]
2755 pub enum ImplOverlapKind {
2756 /// These impls are always allowed to overlap.
2758 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
2761 /// These impls are allowed to overlap, but that raises
2762 /// an issue #33140 future-compatibility warning.
2764 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2765 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2767 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2768 /// that difference, making what reduces to the following set of impls:
2772 /// impl Trait for dyn Send + Sync {}
2773 /// impl Trait for dyn Sync + Send {}
2776 /// Obviously, once we made these types be identical, that code causes a coherence
2777 /// error and a fairly big headache for us. However, luckily for us, the trait
2778 /// `Trait` used in this case is basically a marker trait, and therefore having
2779 /// overlapping impls for it is sound.
2781 /// To handle this, we basically regard the trait as a marker trait, with an additional
2782 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2783 /// it has the following restrictions:
2785 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2787 /// 2. The trait-ref of both impls must be equal.
2788 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2790 /// 4. Neither of the impls can have any where-clauses.
2792 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2796 impl<'tcx> TyCtxt<'tcx> {
2797 pub fn body_tables(self, body: hir::BodyId) -> &'tcx TypeckTables<'tcx> {
2798 self.typeck_tables_of(self.hir().body_owner_def_id(body))
2801 /// Returns an iterator of the `DefId`s for all body-owners in this
2802 /// crate. If you would prefer to iterate over the bodies
2803 /// themselves, you can do `self.hir().krate().body_ids.iter()`.
2804 pub fn body_owners(self) -> impl Iterator<Item = DefId> + Captures<'tcx> + 'tcx {
2809 .map(move |&body_id| self.hir().body_owner_def_id(body_id))
2812 pub fn par_body_owners<F: Fn(DefId) + sync::Sync + sync::Send>(self, f: F) {
2813 par_iter(&self.hir().krate().body_ids)
2814 .for_each(|&body_id| f(self.hir().body_owner_def_id(body_id)));
2817 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
2818 self.associated_items(id)
2819 .in_definition_order()
2820 .filter(|item| item.kind == AssocKind::Method && item.defaultness.has_value())
2823 pub fn trait_relevant_for_never(self, did: DefId) -> bool {
2824 self.associated_items(did).in_definition_order().any(|item| item.relevant_for_never())
2827 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
2828 self.hir().as_local_hir_id(def_id).and_then(|hir_id| self.hir().get(hir_id).ident())
2831 pub fn opt_associated_item(self, def_id: DefId) -> Option<AssocItem> {
2832 let is_associated_item = if let Some(hir_id) = self.hir().as_local_hir_id(def_id) {
2833 match self.hir().get(hir_id) {
2834 Node::TraitItem(_) | Node::ImplItem(_) => true,
2838 match self.def_kind(def_id).expect("no def for `DefId`") {
2839 DefKind::AssocConst | DefKind::Method | DefKind::AssocTy => true,
2844 is_associated_item.then(|| self.associated_item(def_id))
2847 pub fn field_index(self, hir_id: hir::HirId, tables: &TypeckTables<'_>) -> usize {
2848 tables.field_indices().get(hir_id).cloned().expect("no index for a field")
2851 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2852 variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id))
2855 /// Returns `true` if the impls are the same polarity and the trait either
2856 /// has no items or is annotated #[marker] and prevents item overrides.
2857 pub fn impls_are_allowed_to_overlap(
2861 ) -> Option<ImplOverlapKind> {
2862 // If either trait impl references an error, they're allowed to overlap,
2863 // as one of them essentially doesn't exist.
2864 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2865 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2867 return Some(ImplOverlapKind::Permitted { marker: false });
2870 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2871 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2872 // `#[rustc_reservation_impl]` impls don't overlap with anything
2874 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2877 return Some(ImplOverlapKind::Permitted { marker: false });
2879 (ImplPolarity::Positive, ImplPolarity::Negative)
2880 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2881 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2883 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2888 (ImplPolarity::Positive, ImplPolarity::Positive)
2889 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2892 let is_marker_overlap = {
2893 let is_marker_impl = |def_id: DefId| -> bool {
2894 let trait_ref = self.impl_trait_ref(def_id);
2895 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2897 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2900 if is_marker_overlap {
2902 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2905 Some(ImplOverlapKind::Permitted { marker: true })
2907 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2908 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2909 if self_ty1 == self_ty2 {
2911 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2914 return Some(ImplOverlapKind::Issue33140);
2917 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2918 def_id1, def_id2, self_ty1, self_ty2
2924 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2929 /// Returns `ty::VariantDef` if `res` refers to a struct,
2930 /// or variant or their constructors, panics otherwise.
2931 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2933 Res::Def(DefKind::Variant, did) => {
2934 let enum_did = self.parent(did).unwrap();
2935 self.adt_def(enum_did).variant_with_id(did)
2937 Res::Def(DefKind::Struct, did) | Res::Def(DefKind::Union, did) => {
2938 self.adt_def(did).non_enum_variant()
2940 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2941 let variant_did = self.parent(variant_ctor_did).unwrap();
2942 let enum_did = self.parent(variant_did).unwrap();
2943 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2945 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2946 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2947 self.adt_def(struct_did).non_enum_variant()
2949 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2953 pub fn item_name(self, id: DefId) -> Symbol {
2954 if id.index == CRATE_DEF_INDEX {
2955 self.original_crate_name(id.krate)
2957 let def_key = self.def_key(id);
2958 match def_key.disambiguated_data.data {
2959 // The name of a constructor is that of its parent.
2960 hir_map::DefPathData::Ctor => {
2961 self.item_name(DefId { krate: id.krate, index: def_key.parent.unwrap() })
2963 _ => def_key.disambiguated_data.data.get_opt_name().unwrap_or_else(|| {
2964 bug!("item_name: no name for {:?}", self.def_path(id));
2970 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2971 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> ReadOnlyBodyAndCache<'tcx, 'tcx> {
2973 ty::InstanceDef::Item(did) => self.optimized_mir(did).unwrap_read_only(),
2974 ty::InstanceDef::VtableShim(..)
2975 | ty::InstanceDef::ReifyShim(..)
2976 | ty::InstanceDef::Intrinsic(..)
2977 | ty::InstanceDef::FnPtrShim(..)
2978 | ty::InstanceDef::Virtual(..)
2979 | ty::InstanceDef::ClosureOnceShim { .. }
2980 | ty::InstanceDef::DropGlue(..)
2981 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance).unwrap_read_only(),
2985 /// Gets the attributes of a definition.
2986 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
2987 if let Some(id) = self.hir().as_local_hir_id(did) {
2988 Attributes::Borrowed(self.hir().attrs(id))
2990 Attributes::Owned(self.item_attrs(did))
2994 /// Determines whether an item is annotated with an attribute.
2995 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2996 attr::contains_name(&self.get_attrs(did), attr)
2999 /// Returns `true` if this is an `auto trait`.
3000 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
3001 self.trait_def(trait_def_id).has_auto_impl
3004 pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
3005 self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
3008 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
3009 /// If it implements no trait, returns `None`.
3010 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
3011 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
3014 /// If the given defid describes a method belonging to an impl, returns the
3015 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
3016 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
3017 let item = if def_id.krate != LOCAL_CRATE {
3018 if let Some(DefKind::Method) = self.def_kind(def_id) {
3019 Some(self.associated_item(def_id))
3024 self.opt_associated_item(def_id)
3027 item.and_then(|trait_item| match trait_item.container {
3028 TraitContainer(_) => None,
3029 ImplContainer(def_id) => Some(def_id),
3033 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
3034 /// with the name of the crate containing the impl.
3035 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
3036 if impl_did.is_local() {
3037 let hir_id = self.hir().as_local_hir_id(impl_did).unwrap();
3038 Ok(self.hir().span(hir_id))
3040 Err(self.crate_name(impl_did.krate))
3044 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
3045 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
3046 /// definition's parent/scope to perform comparison.
3047 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
3048 // We could use `Ident::eq` here, but we deliberately don't. The name
3049 // comparison fails frequently, and we want to avoid the expensive
3050 // `modern()` calls required for the span comparison whenever possible.
3051 use_name.name == def_name.name
3055 .hygienic_eq(def_name.span.ctxt(), self.expansion_that_defined(def_parent_def_id))
3058 fn expansion_that_defined(self, scope: DefId) -> ExpnId {
3060 LOCAL_CRATE => self.hir().definitions().expansion_that_defined(scope.index),
3061 _ => ExpnId::root(),
3065 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
3066 ident.span.modernize_and_adjust(self.expansion_that_defined(scope));
3070 pub fn adjust_ident_and_get_scope(
3075 ) -> (Ident, DefId) {
3076 let scope = match ident.span.modernize_and_adjust(self.expansion_that_defined(scope)) {
3077 Some(actual_expansion) => {
3078 self.hir().definitions().parent_module_of_macro_def(actual_expansion)
3080 None => self.hir().get_module_parent(block),
3085 pub fn is_object_safe(self, key: DefId) -> bool {
3086 self.object_safety_violations(key).is_empty()
3090 #[derive(Clone, HashStable)]
3091 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
3093 /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition.
3094 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
3095 if let Some(hir_id) = tcx.hir().as_local_hir_id(def_id) {
3096 if let Node::Item(item) = tcx.hir().get(hir_id) {
3097 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
3098 return opaque_ty.impl_trait_fn;
3105 pub fn provide(providers: &mut ty::query::Providers<'_>) {
3106 context::provide(providers);
3107 erase_regions::provide(providers);
3108 layout::provide(providers);
3110 ty::query::Providers { trait_impls_of: trait_def::trait_impls_of_provider, ..*providers };
3113 /// A map for the local crate mapping each type to a vector of its
3114 /// inherent impls. This is not meant to be used outside of coherence;
3115 /// rather, you should request the vector for a specific type via
3116 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
3117 /// (constructing this map requires touching the entire crate).
3118 #[derive(Clone, Debug, Default, HashStable)]
3119 pub struct CrateInherentImpls {
3120 pub inherent_impls: DefIdMap<Vec<DefId>>,
3123 #[derive(Clone, Copy, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
3124 pub struct SymbolName {
3125 // FIXME: we don't rely on interning or equality here - better have
3126 // this be a `&'tcx str`.
3131 pub fn new(name: &str) -> SymbolName {
3132 SymbolName { name: Symbol::intern(name) }
3136 impl PartialOrd for SymbolName {
3137 fn partial_cmp(&self, other: &SymbolName) -> Option<Ordering> {
3138 self.name.as_str().partial_cmp(&other.name.as_str())
3142 /// Ordering must use the chars to ensure reproducible builds.
3143 impl Ord for SymbolName {
3144 fn cmp(&self, other: &SymbolName) -> Ordering {
3145 self.name.as_str().cmp(&other.name.as_str())
3149 impl fmt::Display for SymbolName {
3150 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3151 fmt::Display::fmt(&self.name, fmt)
3155 impl fmt::Debug for SymbolName {
3156 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3157 fmt::Display::fmt(&self.name, fmt)