1 //! Defines how the compiler represents types internally.
3 //! Two important entities in this module are:
5 //! - [`rustc_middle::ty::Ty`], used to represent the semantics of a type.
6 //! - [`rustc_middle::ty::TyCtxt`], the central data structure in the compiler.
8 //! For more information, see ["The `ty` module: representing types"] in the ructc-dev-guide.
10 //! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html
12 // ignore-tidy-filelength
13 pub use self::fold::{TypeFoldable, TypeFolder, TypeVisitor};
14 pub use self::AssocItemContainer::*;
15 pub use self::BorrowKind::*;
16 pub use self::IntVarValue::*;
17 pub use self::Variance::*;
20 use crate::hir::exports::ExportMap;
21 use crate::hir::place::{
22 Place as HirPlace, PlaceBase as HirPlaceBase, ProjectionKind as HirProjectionKind,
24 use crate::ich::StableHashingContext;
25 use crate::middle::cstore::CrateStoreDyn;
26 use crate::middle::resolve_lifetime::ObjectLifetimeDefault;
27 use crate::mir::interpret::ErrorHandled;
28 use crate::mir::{Body, GeneratorLayout};
29 use crate::traits::{self, Reveal};
31 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
32 use crate::ty::util::{Discr, IntTypeExt};
34 use rustc_attr as attr;
35 use rustc_data_structures::captures::Captures;
36 use rustc_data_structures::fingerprint::Fingerprint;
37 use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap};
38 use rustc_data_structures::sorted_map::SortedIndexMultiMap;
39 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
40 use rustc_data_structures::sync::{self, par_iter, ParallelIterator};
41 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
42 use rustc_errors::ErrorReported;
44 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Namespace, Res};
45 use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, CRATE_DEF_INDEX};
46 use rustc_hir::lang_items::LangItem;
47 use rustc_hir::{Constness, Node};
48 use rustc_index::vec::{Idx, IndexVec};
49 use rustc_macros::HashStable;
50 use rustc_serialize::{self, Encodable, Encoder};
51 use rustc_session::DataTypeKind;
52 use rustc_span::hygiene::ExpnId;
53 use rustc_span::symbol::{kw, sym, Ident, Symbol};
55 use rustc_target::abi::{Align, VariantIdx};
57 use std::cell::RefCell;
58 use std::cmp::Ordering;
59 use std::hash::{Hash, Hasher};
60 use std::ops::{ControlFlow, Range};
61 use std::{fmt, ptr, str};
63 pub use crate::ty::diagnostics::*;
64 pub use rustc_type_ir::InferTy::*;
65 pub use rustc_type_ir::*;
67 pub use self::binding::BindingMode;
68 pub use self::binding::BindingMode::*;
69 pub use self::consts::{Const, ConstInt, ConstKind, InferConst, ScalarInt};
70 pub use self::context::{
71 tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
72 CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorInteriorTypeCause, GlobalCtxt,
73 Lift, ResolvedOpaqueTy, TyCtxt, TypeckResults, UserType, UserTypeAnnotationIndex,
75 pub use self::instance::{Instance, InstanceDef};
76 pub use self::list::List;
77 pub use self::sty::BoundRegionKind::*;
78 pub use self::sty::RegionKind::*;
79 pub use self::sty::TyKind::*;
81 Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, CanonicalPolyFnSig,
82 ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBoundRegion, ExistentialPredicate,
83 ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig, GeneratorSubsts,
84 GeneratorSubstsParts, ParamConst, ParamTy, PolyExistentialProjection, PolyExistentialTraitRef,
85 PolyFnSig, PolyGenSig, PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef,
86 TyKind, TypeAndMut, UpvarSubsts,
88 pub use self::trait_def::TraitDef;
99 pub mod inhabitedness;
101 pub mod normalize_erasing_regions;
117 mod structural_impls;
123 pub struct ResolverOutputs {
124 pub definitions: rustc_hir::definitions::Definitions,
125 pub cstore: Box<CrateStoreDyn>,
126 pub visibilities: FxHashMap<LocalDefId, Visibility>,
127 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
128 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
129 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
130 pub export_map: ExportMap<LocalDefId>,
131 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
132 /// Extern prelude entries. The value is `true` if the entry was introduced
133 /// via `extern crate` item and not `--extern` option or compiler built-in.
134 pub extern_prelude: FxHashMap<Symbol, bool>,
137 #[derive(Clone, Copy, PartialEq, Eq, Debug, HashStable, Hash)]
138 pub enum AssocItemContainer {
139 TraitContainer(DefId),
140 ImplContainer(DefId),
143 impl AssocItemContainer {
144 /// Asserts that this is the `DefId` of an associated item declared
145 /// in a trait, and returns the trait `DefId`.
146 pub fn assert_trait(&self) -> DefId {
148 TraitContainer(id) => id,
149 _ => bug!("associated item has wrong container type: {:?}", self),
153 pub fn id(&self) -> DefId {
155 TraitContainer(id) => id,
156 ImplContainer(id) => id,
161 /// The "header" of an impl is everything outside the body: a Self type, a trait
162 /// ref (in the case of a trait impl), and a set of predicates (from the
163 /// bounds / where-clauses).
164 #[derive(Clone, Debug, TypeFoldable)]
165 pub struct ImplHeader<'tcx> {
166 pub impl_def_id: DefId,
167 pub self_ty: Ty<'tcx>,
168 pub trait_ref: Option<TraitRef<'tcx>>,
169 pub predicates: Vec<Predicate<'tcx>>,
172 #[derive(Copy, Clone, PartialEq, TyEncodable, TyDecodable, HashStable, Debug)]
173 pub enum ImplPolarity {
174 /// `impl Trait for Type`
176 /// `impl !Trait for Type`
178 /// `#[rustc_reservation_impl] impl Trait for Type`
180 /// This is a "stability hack", not a real Rust feature.
181 /// See #64631 for details.
185 #[derive(Copy, Clone, Debug, PartialEq, HashStable, Eq, Hash)]
186 pub struct AssocItem {
188 #[stable_hasher(project(name))]
192 pub defaultness: hir::Defaultness,
193 pub container: AssocItemContainer,
195 /// Whether this is a method with an explicit self
196 /// as its first parameter, allowing method calls.
197 pub fn_has_self_parameter: bool,
200 #[derive(Copy, Clone, PartialEq, Debug, HashStable, Eq, Hash)]
208 pub fn namespace(&self) -> Namespace {
210 ty::AssocKind::Type => Namespace::TypeNS,
211 ty::AssocKind::Const | ty::AssocKind::Fn => Namespace::ValueNS,
215 pub fn as_def_kind(&self) -> DefKind {
217 AssocKind::Const => DefKind::AssocConst,
218 AssocKind::Fn => DefKind::AssocFn,
219 AssocKind::Type => DefKind::AssocTy,
225 pub fn signature(&self, tcx: TyCtxt<'_>) -> String {
227 ty::AssocKind::Fn => {
228 // We skip the binder here because the binder would deanonymize all
229 // late-bound regions, and we don't want method signatures to show up
230 // `as for<'r> fn(&'r MyType)`. Pretty-printing handles late-bound
231 // regions just fine, showing `fn(&MyType)`.
232 tcx.fn_sig(self.def_id).skip_binder().to_string()
234 ty::AssocKind::Type => format!("type {};", self.ident),
235 ty::AssocKind::Const => {
236 format!("const {}: {:?};", self.ident, tcx.type_of(self.def_id))
242 /// A list of `ty::AssocItem`s in definition order that allows for efficient lookup by name.
244 /// When doing lookup by name, we try to postpone hygienic comparison for as long as possible since
245 /// it is relatively expensive. Instead, items are indexed by `Symbol` and hygienic comparison is
246 /// done only on items with the same name.
247 #[derive(Debug, Clone, PartialEq, HashStable)]
248 pub struct AssociatedItems<'tcx> {
249 items: SortedIndexMultiMap<u32, Symbol, &'tcx ty::AssocItem>,
252 impl<'tcx> AssociatedItems<'tcx> {
253 /// Constructs an `AssociatedItems` map from a series of `ty::AssocItem`s in definition order.
254 pub fn new(items_in_def_order: impl IntoIterator<Item = &'tcx ty::AssocItem>) -> Self {
255 let items = items_in_def_order.into_iter().map(|item| (item.ident.name, item)).collect();
256 AssociatedItems { items }
259 /// Returns a slice of associated items in the order they were defined.
261 /// New code should avoid relying on definition order. If you need a particular associated item
262 /// for a known trait, make that trait a lang item instead of indexing this array.
263 pub fn in_definition_order(&self) -> impl '_ + Iterator<Item = &ty::AssocItem> {
264 self.items.iter().map(|(_, v)| *v)
267 pub fn len(&self) -> usize {
271 /// Returns an iterator over all associated items with the given name, ignoring hygiene.
272 pub fn filter_by_name_unhygienic(
275 ) -> impl '_ + Iterator<Item = &ty::AssocItem> {
276 self.items.get_by_key(&name).copied()
279 /// Returns an iterator over all associated items with the given name.
281 /// Multiple items may have the same name if they are in different `Namespace`s. For example,
282 /// an associated type can have the same name as a method. Use one of the `find_by_name_and_*`
283 /// methods below if you know which item you are looking for.
284 pub fn filter_by_name(
288 parent_def_id: DefId,
289 ) -> impl 'a + Iterator<Item = &'a ty::AssocItem> {
290 self.filter_by_name_unhygienic(ident.name)
291 .filter(move |item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
294 /// Returns the associated item with the given name and `AssocKind`, if one exists.
295 pub fn find_by_name_and_kind(
300 parent_def_id: DefId,
301 ) -> Option<&ty::AssocItem> {
302 self.filter_by_name_unhygienic(ident.name)
303 .filter(|item| item.kind == kind)
304 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
307 /// Returns the associated item with the given name in the given `Namespace`, if one exists.
308 pub fn find_by_name_and_namespace(
313 parent_def_id: DefId,
314 ) -> Option<&ty::AssocItem> {
315 self.filter_by_name_unhygienic(ident.name)
316 .filter(|item| item.kind.namespace() == ns)
317 .find(|item| tcx.hygienic_eq(ident, item.ident, parent_def_id))
321 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
322 pub enum Visibility {
323 /// Visible everywhere (including in other crates).
325 /// Visible only in the given crate-local module.
327 /// Not visible anywhere in the local crate. This is the visibility of private external items.
331 pub trait DefIdTree: Copy {
332 fn parent(self, id: DefId) -> Option<DefId>;
334 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
335 if descendant.krate != ancestor.krate {
339 while descendant != ancestor {
340 match self.parent(descendant) {
341 Some(parent) => descendant = parent,
342 None => return false,
349 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
350 fn parent(self, id: DefId) -> Option<DefId> {
351 self.def_key(id).parent.map(|index| DefId { index, ..id })
356 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
357 match visibility.node {
358 hir::VisibilityKind::Public => Visibility::Public,
359 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
360 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
361 // If there is no resolution, `resolve` will have already reported an error, so
362 // assume that the visibility is public to avoid reporting more privacy errors.
363 Res::Err => Visibility::Public,
364 def => Visibility::Restricted(def.def_id()),
366 hir::VisibilityKind::Inherited => {
367 Visibility::Restricted(tcx.parent_module(id).to_def_id())
372 /// Returns `true` if an item with this visibility is accessible from the given block.
373 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
374 let restriction = match self {
375 // Public items are visible everywhere.
376 Visibility::Public => return true,
377 // Private items from other crates are visible nowhere.
378 Visibility::Invisible => return false,
379 // Restricted items are visible in an arbitrary local module.
380 Visibility::Restricted(other) if other.krate != module.krate => return false,
381 Visibility::Restricted(module) => module,
384 tree.is_descendant_of(module, restriction)
387 /// Returns `true` if this visibility is at least as accessible as the given visibility
388 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
389 let vis_restriction = match vis {
390 Visibility::Public => return self == Visibility::Public,
391 Visibility::Invisible => return true,
392 Visibility::Restricted(module) => module,
395 self.is_accessible_from(vis_restriction, tree)
398 // Returns `true` if this item is visible anywhere in the local crate.
399 pub fn is_visible_locally(self) -> bool {
401 Visibility::Public => true,
402 Visibility::Restricted(def_id) => def_id.is_local(),
403 Visibility::Invisible => false,
408 /// The crate variances map is computed during typeck and contains the
409 /// variance of every item in the local crate. You should not use it
410 /// directly, because to do so will make your pass dependent on the
411 /// HIR of every item in the local crate. Instead, use
412 /// `tcx.variances_of()` to get the variance for a *particular*
414 #[derive(HashStable, Debug)]
415 pub struct CrateVariancesMap<'tcx> {
416 /// For each item with generics, maps to a vector of the variance
417 /// of its generics. If an item has no generics, it will have no
419 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
422 // Contains information needed to resolve types and (in the future) look up
423 // the types of AST nodes.
424 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
425 pub struct CReaderCacheKey {
430 #[allow(rustc::usage_of_ty_tykind)]
431 pub struct TyS<'tcx> {
432 /// This field shouldn't be used directly and may be removed in the future.
433 /// Use `TyS::kind()` instead.
435 /// This field shouldn't be used directly and may be removed in the future.
436 /// Use `TyS::flags()` instead.
439 /// This is a kind of confusing thing: it stores the smallest
442 /// (a) the binder itself captures nothing but
443 /// (b) all the late-bound things within the type are captured
444 /// by some sub-binder.
446 /// So, for a type without any late-bound things, like `u32`, this
447 /// will be *innermost*, because that is the innermost binder that
448 /// captures nothing. But for a type `&'D u32`, where `'D` is a
449 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
450 /// -- the binder itself does not capture `D`, but `D` is captured
451 /// by an inner binder.
453 /// We call this concept an "exclusive" binder `D` because all
454 /// De Bruijn indices within the type are contained within `0..D`
456 outer_exclusive_binder: ty::DebruijnIndex,
459 impl<'tcx> TyS<'tcx> {
460 /// A constructor used only for internal testing.
461 #[allow(rustc::usage_of_ty_tykind)]
462 pub fn make_for_test(
465 outer_exclusive_binder: ty::DebruijnIndex,
467 TyS { kind, flags, outer_exclusive_binder }
471 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
472 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
473 static_assert_size!(TyS<'_>, 32);
475 impl<'tcx> Ord for TyS<'tcx> {
476 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
477 self.kind().cmp(other.kind())
481 impl<'tcx> PartialOrd for TyS<'tcx> {
482 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
483 Some(self.kind().cmp(other.kind()))
487 impl<'tcx> PartialEq for TyS<'tcx> {
489 fn eq(&self, other: &TyS<'tcx>) -> bool {
493 impl<'tcx> Eq for TyS<'tcx> {}
495 impl<'tcx> Hash for TyS<'tcx> {
496 fn hash<H: Hasher>(&self, s: &mut H) {
497 (self as *const TyS<'_>).hash(s)
501 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
502 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
506 // The other fields just provide fast access to information that is
507 // also contained in `kind`, so no need to hash them.
510 outer_exclusive_binder: _,
513 kind.hash_stable(hcx, hasher);
517 #[rustc_diagnostic_item = "Ty"]
518 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
520 #[derive(Clone, PartialEq, Debug, TyEncodable, TyDecodable, TypeFoldable, Copy, HashStable)]
521 pub enum BorrowKind {
522 /// Data must be immutable and is aliasable.
525 /// Data must be immutable but not aliasable. This kind of borrow
526 /// cannot currently be expressed by the user and is used only in
527 /// implicit closure bindings. It is needed when the closure
528 /// is borrowing or mutating a mutable referent, e.g.:
531 /// let x: &mut isize = ...;
532 /// let y = || *x += 5;
535 /// If we were to try to translate this closure into a more explicit
536 /// form, we'd encounter an error with the code as written:
539 /// struct Env { x: & &mut isize }
540 /// let x: &mut isize = ...;
541 /// let y = (&mut Env { &x }, fn_ptr); // Closure is pair of env and fn
542 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
545 /// This is then illegal because you cannot mutate a `&mut` found
546 /// in an aliasable location. To solve, you'd have to translate with
547 /// an `&mut` borrow:
550 /// struct Env { x: & &mut isize }
551 /// let x: &mut isize = ...;
552 /// let y = (&mut Env { &mut x }, fn_ptr); // changed from &x to &mut x
553 /// fn fn_ptr(env: &mut Env) { **env.x += 5; }
556 /// Now the assignment to `**env.x` is legal, but creating a
557 /// mutable pointer to `x` is not because `x` is not mutable. We
558 /// could fix this by declaring `x` as `let mut x`. This is ok in
559 /// user code, if awkward, but extra weird for closures, since the
560 /// borrow is hidden.
562 /// So we introduce a "unique imm" borrow -- the referent is
563 /// immutable, but not aliasable. This solves the problem. For
564 /// simplicity, we don't give users the way to express this
565 /// borrow, it's just used when translating closures.
568 /// Data is mutable and not aliasable.
572 /// Given the closure DefId this map provides a map of root variables to minimum
573 /// set of `CapturedPlace`s that need to be tracked to support all captures of that closure.
574 pub type MinCaptureInformationMap<'tcx> = FxHashMap<DefId, RootVariableMinCaptureList<'tcx>>;
576 /// Part of `MinCaptureInformationMap`; Maps a root variable to the list of `CapturedPlace`.
577 /// Used to track the minimum set of `Place`s that need to be captured to support all
578 /// Places captured by the closure starting at a given root variable.
580 /// This provides a convenient and quick way of checking if a variable being used within
581 /// a closure is a capture of a local variable.
582 pub type RootVariableMinCaptureList<'tcx> = FxIndexMap<hir::HirId, MinCaptureList<'tcx>>;
584 /// Part of `MinCaptureInformationMap`; List of `CapturePlace`s.
585 pub type MinCaptureList<'tcx> = Vec<CapturedPlace<'tcx>>;
587 /// A composite describing a `Place` that is captured by a closure.
588 #[derive(PartialEq, Clone, Debug, TyEncodable, TyDecodable, TypeFoldable, HashStable)]
589 pub struct CapturedPlace<'tcx> {
590 /// The `Place` that is captured.
591 pub place: HirPlace<'tcx>,
593 /// `CaptureKind` and expression(s) that resulted in such capture of `place`.
594 pub info: CaptureInfo<'tcx>,
596 /// Represents if `place` can be mutated or not.
597 pub mutability: hir::Mutability,
600 impl CapturedPlace<'tcx> {
601 /// Returns the hir-id of the root variable for the captured place.
602 /// e.g., if `a.b.c` was captured, would return the hir-id for `a`.
603 pub fn get_root_variable(&self) -> hir::HirId {
604 match self.place.base {
605 HirPlaceBase::Upvar(upvar_id) => upvar_id.var_path.hir_id,
606 base => bug!("Expected upvar, found={:?}", base),
611 pub fn place_to_string_for_capture(tcx: TyCtxt<'tcx>, place: &HirPlace<'tcx>) -> String {
612 let name = match place.base {
613 HirPlaceBase::Upvar(upvar_id) => tcx.hir().name(upvar_id.var_path.hir_id).to_string(),
614 _ => bug!("Capture_information should only contain upvars"),
616 let mut curr_string = name;
618 for (i, proj) in place.projections.iter().enumerate() {
620 HirProjectionKind::Deref => {
621 curr_string = format!("*{}", curr_string);
623 HirProjectionKind::Field(idx, variant) => match place.ty_before_projection(i).kind() {
624 ty::Adt(def, ..) => {
625 curr_string = format!(
628 def.variants[variant].fields[idx as usize].ident.name.as_str()
632 curr_string = format!("{}.{}", curr_string, idx);
636 "Field projection applied to a type other than Adt or Tuple: {:?}.",
637 place.ty_before_projection(i).kind()
641 proj => bug!("{:?} unexpected because it isn't captured", proj),
645 curr_string.to_string()
648 /// Part of `MinCaptureInformationMap`; describes the capture kind (&, &mut, move)
649 /// for a particular capture as well as identifying the part of the source code
650 /// that triggered this capture to occur.
651 #[derive(PartialEq, Clone, Debug, Copy, TyEncodable, TyDecodable, TypeFoldable, HashStable)]
652 pub struct CaptureInfo<'tcx> {
653 /// Expr Id pointing to use that resulted in selecting the current capture kind
657 /// let mut t = (0,1);
660 /// println!("{}",t); // L1
664 /// `capture_kind_expr_id` will point to the use on L2 and `path_expr_id` will point to the
667 /// If the user doesn't enable feature `capture_disjoint_fields` (RFC 2229) then, it is
668 /// possible that we don't see the use of a particular place resulting in capture_kind_expr_id being
669 /// None. In such case we fallback on uvpars_mentioned for span.
680 /// In this example, if `capture_disjoint_fields` is **not** set, then x will be captured,
681 /// but we won't see it being used during capture analysis, since it's essentially a discard.
682 pub capture_kind_expr_id: Option<hir::HirId>,
683 /// Expr Id pointing to use that resulted the corresponding place being captured
685 /// See `capture_kind_expr_id` for example.
687 pub path_expr_id: Option<hir::HirId>,
689 /// Capture mode that was selected
690 pub capture_kind: UpvarCapture<'tcx>,
693 impl ty::EarlyBoundRegion {
694 /// Does this early bound region have a name? Early bound regions normally
695 /// always have names except when using anonymous lifetimes (`'_`).
696 pub fn has_name(&self) -> bool {
697 self.name != kw::UnderscoreLifetime
701 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
702 pub enum GenericParamDefKind {
706 object_lifetime_default: ObjectLifetimeDefault,
707 synthetic: Option<hir::SyntheticTyParamKind>,
712 impl GenericParamDefKind {
713 pub fn descr(&self) -> &'static str {
715 GenericParamDefKind::Lifetime => "lifetime",
716 GenericParamDefKind::Type { .. } => "type",
717 GenericParamDefKind::Const => "constant",
720 pub fn to_ord(&self, tcx: TyCtxt<'_>) -> ast::ParamKindOrd {
722 GenericParamDefKind::Lifetime => ast::ParamKindOrd::Lifetime,
723 GenericParamDefKind::Type { .. } => ast::ParamKindOrd::Type,
724 GenericParamDefKind::Const => {
725 ast::ParamKindOrd::Const { unordered: tcx.features().const_generics }
731 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
732 pub struct GenericParamDef {
737 /// `pure_wrt_drop`, set by the (unsafe) `#[may_dangle]` attribute
738 /// on generic parameter `'a`/`T`, asserts data behind the parameter
739 /// `'a`/`T` won't be accessed during the parent type's `Drop` impl.
740 pub pure_wrt_drop: bool,
742 pub kind: GenericParamDefKind,
745 impl GenericParamDef {
746 pub fn to_early_bound_region_data(&self) -> ty::EarlyBoundRegion {
747 if let GenericParamDefKind::Lifetime = self.kind {
748 ty::EarlyBoundRegion { def_id: self.def_id, index: self.index, name: self.name }
750 bug!("cannot convert a non-lifetime parameter def to an early bound region")
756 pub struct GenericParamCount {
757 pub lifetimes: usize,
762 /// Information about the formal type/lifetime parameters associated
763 /// with an item or method. Analogous to `hir::Generics`.
765 /// The ordering of parameters is the same as in `Subst` (excluding child generics):
766 /// `Self` (optionally), `Lifetime` params..., `Type` params...
767 #[derive(Clone, Debug, TyEncodable, TyDecodable, HashStable)]
768 pub struct Generics {
769 pub parent: Option<DefId>,
770 pub parent_count: usize,
771 pub params: Vec<GenericParamDef>,
773 /// Reverse map to the `index` field of each `GenericParamDef`.
774 #[stable_hasher(ignore)]
775 pub param_def_id_to_index: FxHashMap<DefId, u32>,
778 pub has_late_bound_regions: Option<Span>,
781 impl<'tcx> Generics {
782 pub fn count(&self) -> usize {
783 self.parent_count + self.params.len()
786 pub fn own_counts(&self) -> GenericParamCount {
787 // We could cache this as a property of `GenericParamCount`, but
788 // the aim is to refactor this away entirely eventually and the
789 // presence of this method will be a constant reminder.
790 let mut own_counts = GenericParamCount::default();
792 for param in &self.params {
794 GenericParamDefKind::Lifetime => own_counts.lifetimes += 1,
795 GenericParamDefKind::Type { .. } => own_counts.types += 1,
796 GenericParamDefKind::Const => own_counts.consts += 1,
803 pub fn own_defaults(&self) -> GenericParamCount {
804 let mut own_defaults = GenericParamCount::default();
806 for param in &self.params {
808 GenericParamDefKind::Lifetime => (),
809 GenericParamDefKind::Type { has_default, .. } => {
810 own_defaults.types += has_default as usize;
812 GenericParamDefKind::Const => {
813 // FIXME(const_generics:defaults)
821 pub fn requires_monomorphization(&self, tcx: TyCtxt<'tcx>) -> bool {
822 if self.own_requires_monomorphization() {
826 if let Some(parent_def_id) = self.parent {
827 let parent = tcx.generics_of(parent_def_id);
828 parent.requires_monomorphization(tcx)
834 pub fn own_requires_monomorphization(&self) -> bool {
835 for param in &self.params {
837 GenericParamDefKind::Type { .. } | GenericParamDefKind::Const => return true,
838 GenericParamDefKind::Lifetime => {}
844 /// Returns the `GenericParamDef` with the given index.
845 pub fn param_at(&'tcx self, param_index: usize, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
846 if let Some(index) = param_index.checked_sub(self.parent_count) {
849 tcx.generics_of(self.parent.expect("parent_count > 0 but no parent?"))
850 .param_at(param_index, tcx)
854 /// Returns the `GenericParamDef` associated with this `EarlyBoundRegion`.
857 param: &EarlyBoundRegion,
859 ) -> &'tcx GenericParamDef {
860 let param = self.param_at(param.index as usize, tcx);
862 GenericParamDefKind::Lifetime => param,
863 _ => bug!("expected lifetime parameter, but found another generic parameter"),
867 /// Returns the `GenericParamDef` associated with this `ParamTy`.
868 pub fn type_param(&'tcx self, param: &ParamTy, tcx: TyCtxt<'tcx>) -> &'tcx GenericParamDef {
869 let param = self.param_at(param.index as usize, tcx);
871 GenericParamDefKind::Type { .. } => param,
872 _ => bug!("expected type parameter, but found another generic parameter"),
876 /// Returns the `GenericParamDef` associated with this `ParamConst`.
877 pub fn const_param(&'tcx self, param: &ParamConst, tcx: TyCtxt<'tcx>) -> &GenericParamDef {
878 let param = self.param_at(param.index as usize, tcx);
880 GenericParamDefKind::Const => param,
881 _ => bug!("expected const parameter, but found another generic parameter"),
886 /// Bounds on generics.
887 #[derive(Copy, Clone, Default, Debug, TyEncodable, TyDecodable, HashStable)]
888 pub struct GenericPredicates<'tcx> {
889 pub parent: Option<DefId>,
890 pub predicates: &'tcx [(Predicate<'tcx>, Span)],
893 impl<'tcx> GenericPredicates<'tcx> {
897 substs: SubstsRef<'tcx>,
898 ) -> InstantiatedPredicates<'tcx> {
899 let mut instantiated = InstantiatedPredicates::empty();
900 self.instantiate_into(tcx, &mut instantiated, substs);
904 pub fn instantiate_own(
907 substs: SubstsRef<'tcx>,
908 ) -> InstantiatedPredicates<'tcx> {
909 InstantiatedPredicates {
910 predicates: self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)).collect(),
911 spans: self.predicates.iter().map(|(_, sp)| *sp).collect(),
918 instantiated: &mut InstantiatedPredicates<'tcx>,
919 substs: SubstsRef<'tcx>,
921 if let Some(def_id) = self.parent {
922 tcx.predicates_of(def_id).instantiate_into(tcx, instantiated, substs);
924 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p.subst(tcx, substs)));
925 instantiated.spans.extend(self.predicates.iter().map(|(_, sp)| *sp));
928 pub fn instantiate_identity(&self, tcx: TyCtxt<'tcx>) -> InstantiatedPredicates<'tcx> {
929 let mut instantiated = InstantiatedPredicates::empty();
930 self.instantiate_identity_into(tcx, &mut instantiated);
934 fn instantiate_identity_into(
937 instantiated: &mut InstantiatedPredicates<'tcx>,
939 if let Some(def_id) = self.parent {
940 tcx.predicates_of(def_id).instantiate_identity_into(tcx, instantiated);
942 instantiated.predicates.extend(self.predicates.iter().map(|(p, _)| p));
943 instantiated.spans.extend(self.predicates.iter().map(|(_, s)| s));
948 crate struct PredicateInner<'tcx> {
949 kind: Binder<PredicateKind<'tcx>>,
951 /// See the comment for the corresponding field of [TyS].
952 outer_exclusive_binder: ty::DebruijnIndex,
955 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
956 static_assert_size!(PredicateInner<'_>, 40);
958 #[derive(Clone, Copy, Lift)]
959 pub struct Predicate<'tcx> {
960 inner: &'tcx PredicateInner<'tcx>,
963 impl<'tcx> PartialEq for Predicate<'tcx> {
964 fn eq(&self, other: &Self) -> bool {
965 // `self.kind` is always interned.
966 ptr::eq(self.inner, other.inner)
970 impl Hash for Predicate<'_> {
971 fn hash<H: Hasher>(&self, s: &mut H) {
972 (self.inner as *const PredicateInner<'_>).hash(s)
976 impl<'tcx> Eq for Predicate<'tcx> {}
978 impl<'tcx> Predicate<'tcx> {
979 /// Gets the inner `Binder<PredicateKind<'tcx>>`.
981 pub fn kind(self) -> Binder<PredicateKind<'tcx>> {
986 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
987 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
991 // The other fields just provide fast access to information that is
992 // also contained in `kind`, so no need to hash them.
994 outer_exclusive_binder: _,
997 kind.hash_stable(hcx, hasher);
1001 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1002 #[derive(HashStable, TypeFoldable)]
1003 pub enum PredicateKind<'tcx> {
1004 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
1005 /// the `Self` type of the trait reference and `A`, `B`, and `C`
1006 /// would be the type parameters.
1008 /// A trait predicate will have `Constness::Const` if it originates
1009 /// from a bound on a `const fn` without the `?const` opt-out (e.g.,
1010 /// `const fn foobar<Foo: Bar>() {}`).
1011 Trait(TraitPredicate<'tcx>, Constness),
1014 RegionOutlives(RegionOutlivesPredicate<'tcx>),
1017 TypeOutlives(TypeOutlivesPredicate<'tcx>),
1019 /// `where <T as TraitRef>::Name == X`, approximately.
1020 /// See the `ProjectionPredicate` struct for details.
1021 Projection(ProjectionPredicate<'tcx>),
1023 /// No syntax: `T` well-formed.
1024 WellFormed(GenericArg<'tcx>),
1026 /// Trait must be object-safe.
1029 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
1030 /// for some substitutions `...` and `T` being a closure type.
1031 /// Satisfied (or refuted) once we know the closure's kind.
1032 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
1035 Subtype(SubtypePredicate<'tcx>),
1037 /// Constant initializer must evaluate successfully.
1038 ConstEvaluatable(ty::WithOptConstParam<DefId>, SubstsRef<'tcx>),
1040 /// Constants must be equal. The first component is the const that is expected.
1041 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
1043 /// Represents a type found in the environment that we can use for implied bounds.
1045 /// Only used for Chalk.
1046 TypeWellFormedFromEnv(Ty<'tcx>),
1049 /// The crate outlives map is computed during typeck and contains the
1050 /// outlives of every item in the local crate. You should not use it
1051 /// directly, because to do so will make your pass dependent on the
1052 /// HIR of every item in the local crate. Instead, use
1053 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
1055 #[derive(HashStable, Debug)]
1056 pub struct CratePredicatesMap<'tcx> {
1057 /// For each struct with outlive bounds, maps to a vector of the
1058 /// predicate of its outlive bounds. If an item has no outlives
1059 /// bounds, it will have no entry.
1060 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
1063 impl<'tcx> Predicate<'tcx> {
1064 /// Performs a substitution suitable for going from a
1065 /// poly-trait-ref to supertraits that must hold if that
1066 /// poly-trait-ref holds. This is slightly different from a normal
1067 /// substitution in terms of what happens with bound regions. See
1068 /// lengthy comment below for details.
1069 pub fn subst_supertrait(
1072 trait_ref: &ty::PolyTraitRef<'tcx>,
1073 ) -> Predicate<'tcx> {
1074 // The interaction between HRTB and supertraits is not entirely
1075 // obvious. Let me walk you (and myself) through an example.
1077 // Let's start with an easy case. Consider two traits:
1079 // trait Foo<'a>: Bar<'a,'a> { }
1080 // trait Bar<'b,'c> { }
1082 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
1083 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
1084 // knew that `Foo<'x>` (for any 'x) then we also know that
1085 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
1086 // normal substitution.
1088 // In terms of why this is sound, the idea is that whenever there
1089 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
1090 // holds. So if there is an impl of `T:Foo<'a>` that applies to
1091 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
1094 // Another example to be careful of is this:
1096 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
1097 // trait Bar1<'b,'c> { }
1099 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
1100 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
1101 // reason is similar to the previous example: any impl of
1102 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
1103 // basically we would want to collapse the bound lifetimes from
1104 // the input (`trait_ref`) and the supertraits.
1106 // To achieve this in practice is fairly straightforward. Let's
1107 // consider the more complicated scenario:
1109 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
1110 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
1111 // where both `'x` and `'b` would have a DB index of 1.
1112 // The substitution from the input trait-ref is therefore going to be
1113 // `'a => 'x` (where `'x` has a DB index of 1).
1114 // - The super-trait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
1115 // early-bound parameter and `'b' is a late-bound parameter with a
1117 // - If we replace `'a` with `'x` from the input, it too will have
1118 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
1119 // just as we wanted.
1121 // There is only one catch. If we just apply the substitution `'a
1122 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
1123 // adjust the DB index because we substituting into a binder (it
1124 // tries to be so smart...) resulting in `for<'x> for<'b>
1125 // Bar1<'x,'b>` (we have no syntax for this, so use your
1126 // imagination). Basically the 'x will have DB index of 2 and 'b
1127 // will have DB index of 1. Not quite what we want. So we apply
1128 // the substitution to the *contents* of the trait reference,
1129 // rather than the trait reference itself (put another way, the
1130 // substitution code expects equal binding levels in the values
1131 // from the substitution and the value being substituted into, and
1132 // this trick achieves that).
1133 let substs = trait_ref.skip_binder().substs;
1134 let pred = self.kind().skip_binder();
1135 let new = pred.subst(tcx, substs);
1136 tcx.reuse_or_mk_predicate(self, ty::Binder::bind(new))
1140 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1141 #[derive(HashStable, TypeFoldable)]
1142 pub struct TraitPredicate<'tcx> {
1143 pub trait_ref: TraitRef<'tcx>,
1146 pub type PolyTraitPredicate<'tcx> = ty::Binder<TraitPredicate<'tcx>>;
1148 impl<'tcx> TraitPredicate<'tcx> {
1149 pub fn def_id(self) -> DefId {
1150 self.trait_ref.def_id
1153 pub fn self_ty(self) -> Ty<'tcx> {
1154 self.trait_ref.self_ty()
1158 impl<'tcx> PolyTraitPredicate<'tcx> {
1159 pub fn def_id(self) -> DefId {
1160 // Ok to skip binder since trait `DefId` does not care about regions.
1161 self.skip_binder().def_id()
1164 pub fn self_ty(self) -> ty::Binder<Ty<'tcx>> {
1165 self.map_bound(|trait_ref| trait_ref.self_ty())
1169 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
1170 #[derive(HashStable, TypeFoldable)]
1171 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
1172 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
1173 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
1174 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<RegionOutlivesPredicate<'tcx>>;
1175 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<TypeOutlivesPredicate<'tcx>>;
1177 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
1178 #[derive(HashStable, TypeFoldable)]
1179 pub struct SubtypePredicate<'tcx> {
1180 pub a_is_expected: bool,
1184 pub type PolySubtypePredicate<'tcx> = ty::Binder<SubtypePredicate<'tcx>>;
1186 /// This kind of predicate has no *direct* correspondent in the
1187 /// syntax, but it roughly corresponds to the syntactic forms:
1189 /// 1. `T: TraitRef<..., Item = Type>`
1190 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
1192 /// In particular, form #1 is "desugared" to the combination of a
1193 /// normal trait predicate (`T: TraitRef<...>`) and one of these
1194 /// predicates. Form #2 is a broader form in that it also permits
1195 /// equality between arbitrary types. Processing an instance of
1196 /// Form #2 eventually yields one of these `ProjectionPredicate`
1197 /// instances to normalize the LHS.
1198 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
1199 #[derive(HashStable, TypeFoldable)]
1200 pub struct ProjectionPredicate<'tcx> {
1201 pub projection_ty: ProjectionTy<'tcx>,
1205 pub type PolyProjectionPredicate<'tcx> = Binder<ProjectionPredicate<'tcx>>;
1207 impl<'tcx> PolyProjectionPredicate<'tcx> {
1208 /// Returns the `DefId` of the associated item being projected.
1209 pub fn item_def_id(&self) -> DefId {
1210 self.skip_binder().projection_ty.item_def_id
1213 /// Returns the `DefId` of the trait of the associated item being projected.
1215 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
1216 self.skip_binder().projection_ty.trait_def_id(tcx)
1220 pub fn projection_self_ty(&self) -> Binder<Ty<'tcx>> {
1221 self.map_bound(|predicate| predicate.projection_ty.self_ty())
1224 /// Get the [PolyTraitRef] required for this projection to be well formed.
1225 /// Note that for generic associated types the predicates of the associated
1226 /// type also need to be checked.
1228 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
1229 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
1230 // `self.0.trait_ref` is permitted to have escaping regions.
1231 // This is because here `self` has a `Binder` and so does our
1232 // return value, so we are preserving the number of binding
1234 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
1237 pub fn ty(&self) -> Binder<Ty<'tcx>> {
1238 self.map_bound(|predicate| predicate.ty)
1241 /// The `DefId` of the `TraitItem` for the associated type.
1243 /// Note that this is not the `DefId` of the `TraitRef` containing this
1244 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
1245 pub fn projection_def_id(&self) -> DefId {
1246 // Ok to skip binder since trait `DefId` does not care about regions.
1247 self.skip_binder().projection_ty.item_def_id
1251 pub trait ToPolyTraitRef<'tcx> {
1252 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
1255 impl<'tcx> ToPolyTraitRef<'tcx> for TraitRef<'tcx> {
1256 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1257 ty::Binder::dummy(*self)
1261 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
1262 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
1263 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
1267 pub trait ToPredicate<'tcx> {
1268 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
1271 impl ToPredicate<'tcx> for Binder<PredicateKind<'tcx>> {
1273 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1274 tcx.mk_predicate(self)
1278 impl ToPredicate<'tcx> for PredicateKind<'tcx> {
1280 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1281 tcx.mk_predicate(Binder::dummy(self))
1285 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<TraitRef<'tcx>> {
1286 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1287 PredicateKind::Trait(ty::TraitPredicate { trait_ref: self.value }, self.constness)
1292 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitRef<'tcx>> {
1293 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1295 value: self.value.map_bound(|trait_ref| ty::TraitPredicate { trait_ref }),
1296 constness: self.constness,
1302 impl<'tcx> ToPredicate<'tcx> for ConstnessAnd<PolyTraitPredicate<'tcx>> {
1303 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1304 self.value.map_bound(|value| PredicateKind::Trait(value, self.constness)).to_predicate(tcx)
1308 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
1309 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1310 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
1314 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
1315 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1316 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
1320 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
1321 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
1322 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
1326 impl<'tcx> Predicate<'tcx> {
1327 pub fn to_opt_poly_trait_ref(self) -> Option<ConstnessAnd<PolyTraitRef<'tcx>>> {
1328 let predicate = self.kind();
1329 match predicate.skip_binder() {
1330 PredicateKind::Trait(t, constness) => {
1331 Some(ConstnessAnd { constness, value: predicate.rebind(t.trait_ref) })
1333 PredicateKind::Projection(..)
1334 | PredicateKind::Subtype(..)
1335 | PredicateKind::RegionOutlives(..)
1336 | PredicateKind::WellFormed(..)
1337 | PredicateKind::ObjectSafe(..)
1338 | PredicateKind::ClosureKind(..)
1339 | PredicateKind::TypeOutlives(..)
1340 | PredicateKind::ConstEvaluatable(..)
1341 | PredicateKind::ConstEquate(..)
1342 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1346 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
1347 let predicate = self.kind();
1348 match predicate.skip_binder() {
1349 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
1350 PredicateKind::Trait(..)
1351 | PredicateKind::Projection(..)
1352 | PredicateKind::Subtype(..)
1353 | PredicateKind::RegionOutlives(..)
1354 | PredicateKind::WellFormed(..)
1355 | PredicateKind::ObjectSafe(..)
1356 | PredicateKind::ClosureKind(..)
1357 | PredicateKind::ConstEvaluatable(..)
1358 | PredicateKind::ConstEquate(..)
1359 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1364 /// Represents the bounds declared on a particular set of type
1365 /// parameters. Should eventually be generalized into a flag list of
1366 /// where-clauses. You can obtain a `InstantiatedPredicates` list from a
1367 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1368 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1369 /// the `GenericPredicates` are expressed in terms of the bound type
1370 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1371 /// represented a set of bounds for some particular instantiation,
1372 /// meaning that the generic parameters have been substituted with
1377 /// struct Foo<T, U: Bar<T>> { ... }
1379 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1380 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1381 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1382 /// [usize:Bar<isize>]]`.
1383 #[derive(Clone, Debug, TypeFoldable)]
1384 pub struct InstantiatedPredicates<'tcx> {
1385 pub predicates: Vec<Predicate<'tcx>>,
1386 pub spans: Vec<Span>,
1389 impl<'tcx> InstantiatedPredicates<'tcx> {
1390 pub fn empty() -> InstantiatedPredicates<'tcx> {
1391 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1394 pub fn is_empty(&self) -> bool {
1395 self.predicates.is_empty()
1399 rustc_index::newtype_index! {
1400 /// "Universes" are used during type- and trait-checking in the
1401 /// presence of `for<..>` binders to control what sets of names are
1402 /// visible. Universes are arranged into a tree: the root universe
1403 /// contains names that are always visible. Each child then adds a new
1404 /// set of names that are visible, in addition to those of its parent.
1405 /// We say that the child universe "extends" the parent universe with
1408 /// To make this more concrete, consider this program:
1412 /// fn bar<T>(x: T) {
1413 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1417 /// The struct name `Foo` is in the root universe U0. But the type
1418 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1419 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1420 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1421 /// region `'a` is in a universe U2 that extends U1, because we can
1422 /// name it inside the fn type but not outside.
1424 /// Universes are used to do type- and trait-checking around these
1425 /// "forall" binders (also called **universal quantification**). The
1426 /// idea is that when, in the body of `bar`, we refer to `T` as a
1427 /// type, we aren't referring to any type in particular, but rather a
1428 /// kind of "fresh" type that is distinct from all other types we have
1429 /// actually declared. This is called a **placeholder** type, and we
1430 /// use universes to talk about this. In other words, a type name in
1431 /// universe 0 always corresponds to some "ground" type that the user
1432 /// declared, but a type name in a non-zero universe is a placeholder
1433 /// type -- an idealized representative of "types in general" that we
1434 /// use for checking generic functions.
1435 pub struct UniverseIndex {
1437 DEBUG_FORMAT = "U{}",
1441 impl UniverseIndex {
1442 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1444 /// Returns the "next" universe index in order -- this new index
1445 /// is considered to extend all previous universes. This
1446 /// corresponds to entering a `forall` quantifier. So, for
1447 /// example, suppose we have this type in universe `U`:
1450 /// for<'a> fn(&'a u32)
1453 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1454 /// new universe that extends `U` -- in this new universe, we can
1455 /// name the region `'a`, but that region was not nameable from
1456 /// `U` because it was not in scope there.
1457 pub fn next_universe(self) -> UniverseIndex {
1458 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1461 /// Returns `true` if `self` can name a name from `other` -- in other words,
1462 /// if the set of names in `self` is a superset of those in
1463 /// `other` (`self >= other`).
1464 pub fn can_name(self, other: UniverseIndex) -> bool {
1465 self.private >= other.private
1468 /// Returns `true` if `self` cannot name some names from `other` -- in other
1469 /// words, if the set of names in `self` is a strict subset of
1470 /// those in `other` (`self < other`).
1471 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1472 self.private < other.private
1476 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1477 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1478 /// regions/types/consts within the same universe simply have an unknown relationship to one
1480 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1481 pub struct Placeholder<T> {
1482 pub universe: UniverseIndex,
1486 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1488 T: HashStable<StableHashingContext<'a>>,
1490 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1491 self.universe.hash_stable(hcx, hasher);
1492 self.name.hash_stable(hcx, hasher);
1496 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1498 pub type PlaceholderType = Placeholder<BoundVar>;
1500 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1501 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1502 pub struct BoundConst<'tcx> {
1507 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1509 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1510 /// the `DefId` of the generic parameter it instantiates.
1512 /// This is used to avoid calls to `type_of` for const arguments during typeck
1513 /// which cause cycle errors.
1518 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1519 /// // ^ const parameter
1523 /// fn foo<const M: u8>(&self) -> usize { 42 }
1524 /// // ^ const parameter
1529 /// let _b = a.foo::<{ 3 + 7 }>();
1530 /// // ^^^^^^^^^ const argument
1534 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1535 /// which `foo` is used until we know the type of `a`.
1537 /// We only know the type of `a` once we are inside of `typeck(main)`.
1538 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1539 /// requires us to evaluate the const argument.
1541 /// To evaluate that const argument we need to know its type,
1542 /// which we would get using `type_of(const_arg)`. This requires us to
1543 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1544 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1545 /// which results in a cycle.
1547 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1549 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1550 /// already resolved `foo` so we know which const parameter this argument instantiates.
1551 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1552 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1553 /// trivial to compute.
1555 /// If we now want to use that constant in a place which potentionally needs its type
1556 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1557 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1558 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1559 /// to get the type of `did`.
1560 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1561 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1562 #[derive(Hash, HashStable)]
1563 pub struct WithOptConstParam<T> {
1565 /// The `DefId` of the corresponding generic parameter in case `did` is
1566 /// a const argument.
1568 /// Note that even if `did` is a const argument, this may still be `None`.
1569 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1570 /// to potentially update `param_did` in the case it is `None`.
1571 pub const_param_did: Option<DefId>,
1574 impl<T> WithOptConstParam<T> {
1575 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1577 pub fn unknown(did: T) -> WithOptConstParam<T> {
1578 WithOptConstParam { did, const_param_did: None }
1582 impl WithOptConstParam<LocalDefId> {
1583 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1584 /// `None` otherwise.
1586 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1587 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1590 /// In case `self` is unknown but `self.did` is a const argument, this returns
1591 /// a `WithOptConstParam` with the correct `const_param_did`.
1593 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1594 if self.const_param_did.is_none() {
1595 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1596 return Some(WithOptConstParam { did: self.did, const_param_did });
1603 pub fn to_global(self) -> WithOptConstParam<DefId> {
1604 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1607 pub fn def_id_for_type_of(self) -> DefId {
1608 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1612 impl WithOptConstParam<DefId> {
1613 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1616 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1619 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1620 if let Some(param_did) = self.const_param_did {
1621 if let Some(did) = self.did.as_local() {
1622 return Some((did, param_did));
1629 pub fn expect_local(self) -> WithOptConstParam<LocalDefId> {
1630 self.as_local().unwrap()
1633 pub fn is_local(self) -> bool {
1637 pub fn def_id_for_type_of(self) -> DefId {
1638 self.const_param_did.unwrap_or(self.did)
1642 /// When type checking, we use the `ParamEnv` to track
1643 /// details about the set of where-clauses that are in scope at this
1644 /// particular point.
1645 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1646 pub struct ParamEnv<'tcx> {
1647 /// This packs both caller bounds and the reveal enum into one pointer.
1649 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1650 /// basically the set of bounds on the in-scope type parameters, translated
1651 /// into `Obligation`s, and elaborated and normalized.
1653 /// Use the `caller_bounds()` method to access.
1655 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1656 /// want `Reveal::All`.
1658 /// Note: This is packed, use the reveal() method to access it.
1659 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, traits::Reveal, true>,
1662 unsafe impl rustc_data_structures::tagged_ptr::Tag for traits::Reveal {
1663 const BITS: usize = 1;
1664 fn into_usize(self) -> usize {
1666 traits::Reveal::UserFacing => 0,
1667 traits::Reveal::All => 1,
1670 unsafe fn from_usize(ptr: usize) -> Self {
1672 0 => traits::Reveal::UserFacing,
1673 1 => traits::Reveal::All,
1674 _ => std::hint::unreachable_unchecked(),
1679 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1680 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1681 f.debug_struct("ParamEnv")
1682 .field("caller_bounds", &self.caller_bounds())
1683 .field("reveal", &self.reveal())
1688 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1689 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1690 self.caller_bounds().hash_stable(hcx, hasher);
1691 self.reveal().hash_stable(hcx, hasher);
1695 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1696 fn super_fold_with<F: ty::fold::TypeFolder<'tcx>>(self, folder: &mut F) -> Self {
1697 ParamEnv::new(self.caller_bounds().fold_with(folder), self.reveal().fold_with(folder))
1700 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1701 self.caller_bounds().visit_with(visitor)?;
1702 self.reveal().visit_with(visitor)
1706 impl<'tcx> ParamEnv<'tcx> {
1707 /// Construct a trait environment suitable for contexts where
1708 /// there are no where-clauses in scope. Hidden types (like `impl
1709 /// Trait`) are left hidden, so this is suitable for ordinary
1712 pub fn empty() -> Self {
1713 Self::new(List::empty(), Reveal::UserFacing)
1717 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1718 self.packed.pointer()
1722 pub fn reveal(self) -> traits::Reveal {
1726 /// Construct a trait environment with no where-clauses in scope
1727 /// where the values of all `impl Trait` and other hidden types
1728 /// are revealed. This is suitable for monomorphized, post-typeck
1729 /// environments like codegen or doing optimizations.
1731 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1732 /// or invoke `param_env.with_reveal_all()`.
1734 pub fn reveal_all() -> Self {
1735 Self::new(List::empty(), Reveal::All)
1738 /// Construct a trait environment with the given set of predicates.
1740 pub fn new(caller_bounds: &'tcx List<Predicate<'tcx>>, reveal: Reveal) -> Self {
1741 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, reveal) }
1744 pub fn with_user_facing(mut self) -> Self {
1745 self.packed.set_tag(Reveal::UserFacing);
1749 /// Returns a new parameter environment with the same clauses, but
1750 /// which "reveals" the true results of projections in all cases
1751 /// (even for associated types that are specializable). This is
1752 /// the desired behavior during codegen and certain other special
1753 /// contexts; normally though we want to use `Reveal::UserFacing`,
1754 /// which is the default.
1755 /// All opaque types in the caller_bounds of the `ParamEnv`
1756 /// will be normalized to their underlying types.
1757 /// See PR #65989 and issue #65918 for more details
1758 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1759 if self.packed.tag() == traits::Reveal::All {
1763 ParamEnv::new(tcx.normalize_opaque_types(self.caller_bounds()), Reveal::All)
1766 /// Returns this same environment but with no caller bounds.
1767 pub fn without_caller_bounds(self) -> Self {
1768 Self::new(List::empty(), self.reveal())
1771 /// Creates a suitable environment in which to perform trait
1772 /// queries on the given value. When type-checking, this is simply
1773 /// the pair of the environment plus value. But when reveal is set to
1774 /// All, then if `value` does not reference any type parameters, we will
1775 /// pair it with the empty environment. This improves caching and is generally
1778 /// N.B., we preserve the environment when type-checking because it
1779 /// is possible for the user to have wacky where-clauses like
1780 /// `where Box<u32>: Copy`, which are clearly never
1781 /// satisfiable. We generally want to behave as if they were true,
1782 /// although the surrounding function is never reachable.
1783 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1784 match self.reveal() {
1785 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1788 if value.is_global() {
1789 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1791 ParamEnvAnd { param_env: self, value }
1798 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1799 pub struct ConstnessAnd<T> {
1800 pub constness: Constness,
1804 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1805 // the constness of trait bounds is being propagated correctly.
1806 pub trait WithConstness: Sized {
1808 fn with_constness(self, constness: Constness) -> ConstnessAnd<Self> {
1809 ConstnessAnd { constness, value: self }
1813 fn with_const(self) -> ConstnessAnd<Self> {
1814 self.with_constness(Constness::Const)
1818 fn without_const(self) -> ConstnessAnd<Self> {
1819 self.with_constness(Constness::NotConst)
1823 impl<T> WithConstness for T {}
1825 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1826 pub struct ParamEnvAnd<'tcx, T> {
1827 pub param_env: ParamEnv<'tcx>,
1831 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1832 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1833 (self.param_env, self.value)
1837 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1839 T: HashStable<StableHashingContext<'a>>,
1841 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1842 let ParamEnvAnd { ref param_env, ref value } = *self;
1844 param_env.hash_stable(hcx, hasher);
1845 value.hash_stable(hcx, hasher);
1849 #[derive(Copy, Clone, Debug, HashStable)]
1850 pub struct Destructor {
1851 /// The `DefId` of the destructor method
1856 #[derive(HashStable)]
1857 pub struct AdtFlags: u32 {
1858 const NO_ADT_FLAGS = 0;
1859 /// Indicates whether the ADT is an enum.
1860 const IS_ENUM = 1 << 0;
1861 /// Indicates whether the ADT is a union.
1862 const IS_UNION = 1 << 1;
1863 /// Indicates whether the ADT is a struct.
1864 const IS_STRUCT = 1 << 2;
1865 /// Indicates whether the ADT is a struct and has a constructor.
1866 const HAS_CTOR = 1 << 3;
1867 /// Indicates whether the type is `PhantomData`.
1868 const IS_PHANTOM_DATA = 1 << 4;
1869 /// Indicates whether the type has a `#[fundamental]` attribute.
1870 const IS_FUNDAMENTAL = 1 << 5;
1871 /// Indicates whether the type is `Box`.
1872 const IS_BOX = 1 << 6;
1873 /// Indicates whether the type is `ManuallyDrop`.
1874 const IS_MANUALLY_DROP = 1 << 7;
1875 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
1876 /// (i.e., this flag is never set unless this ADT is an enum).
1877 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
1882 #[derive(HashStable)]
1883 pub struct VariantFlags: u32 {
1884 const NO_VARIANT_FLAGS = 0;
1885 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1886 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1887 /// Indicates whether this variant was obtained as part of recovering from
1888 /// a syntactic error. May be incomplete or bogus.
1889 const IS_RECOVERED = 1 << 1;
1893 /// Definition of a variant -- a struct's fields or a enum variant.
1894 #[derive(Debug, HashStable)]
1895 pub struct VariantDef {
1896 /// `DefId` that identifies the variant itself.
1897 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1899 /// `DefId` that identifies the variant's constructor.
1900 /// If this variant is a struct variant, then this is `None`.
1901 pub ctor_def_id: Option<DefId>,
1902 /// Variant or struct name.
1903 #[stable_hasher(project(name))]
1905 /// Discriminant of this variant.
1906 pub discr: VariantDiscr,
1907 /// Fields of this variant.
1908 pub fields: Vec<FieldDef>,
1909 /// Type of constructor of variant.
1910 pub ctor_kind: CtorKind,
1911 /// Flags of the variant (e.g. is field list non-exhaustive)?
1912 flags: VariantFlags,
1916 /// Creates a new `VariantDef`.
1918 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1919 /// represents an enum variant).
1921 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1922 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1924 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1925 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1926 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1927 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1928 /// built-in trait), and we do not want to load attributes twice.
1930 /// If someone speeds up attribute loading to not be a performance concern, they can
1931 /// remove this hack and use the constructor `DefId` everywhere.
1934 variant_did: Option<DefId>,
1935 ctor_def_id: Option<DefId>,
1936 discr: VariantDiscr,
1937 fields: Vec<FieldDef>,
1938 ctor_kind: CtorKind,
1942 is_field_list_non_exhaustive: bool,
1945 "VariantDef::new(ident = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1946 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1947 ident, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1950 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1951 if is_field_list_non_exhaustive {
1952 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1956 flags |= VariantFlags::IS_RECOVERED;
1960 def_id: variant_did.unwrap_or(parent_did),
1970 /// Is this field list non-exhaustive?
1972 pub fn is_field_list_non_exhaustive(&self) -> bool {
1973 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1976 /// Was this variant obtained as part of recovering from a syntactic error?
1978 pub fn is_recovered(&self) -> bool {
1979 self.flags.intersects(VariantFlags::IS_RECOVERED)
1983 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1984 pub enum VariantDiscr {
1985 /// Explicit value for this variant, i.e., `X = 123`.
1986 /// The `DefId` corresponds to the embedded constant.
1989 /// The previous variant's discriminant plus one.
1990 /// For efficiency reasons, the distance from the
1991 /// last `Explicit` discriminant is being stored,
1992 /// or `0` for the first variant, if it has none.
1996 #[derive(Debug, HashStable)]
1997 pub struct FieldDef {
1999 #[stable_hasher(project(name))]
2001 pub vis: Visibility,
2004 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
2006 /// These are all interned (by `alloc_adt_def`) into the global arena.
2008 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
2009 /// This is slightly wrong because `union`s are not ADTs.
2010 /// Moreover, Rust only allows recursive data types through indirection.
2012 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
2014 /// The `DefId` of the struct, enum or union item.
2016 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
2017 pub variants: IndexVec<VariantIdx, VariantDef>,
2018 /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
2020 /// Repr options provided by the user.
2021 pub repr: ReprOptions,
2024 impl PartialOrd for AdtDef {
2025 fn partial_cmp(&self, other: &AdtDef) -> Option<Ordering> {
2026 Some(self.cmp(&other))
2030 /// There should be only one AdtDef for each `did`, therefore
2031 /// it is fine to implement `Ord` only based on `did`.
2032 impl Ord for AdtDef {
2033 fn cmp(&self, other: &AdtDef) -> Ordering {
2034 self.did.cmp(&other.did)
2038 impl PartialEq for AdtDef {
2039 // `AdtDef`s are always interned, and this is part of `TyS` equality.
2041 fn eq(&self, other: &Self) -> bool {
2042 ptr::eq(self, other)
2046 impl Eq for AdtDef {}
2048 impl Hash for AdtDef {
2050 fn hash<H: Hasher>(&self, s: &mut H) {
2051 (self as *const AdtDef).hash(s)
2055 impl<S: Encoder> Encodable<S> for AdtDef {
2056 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
2061 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
2062 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
2064 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default();
2067 let hash: Fingerprint = CACHE.with(|cache| {
2068 let addr = self as *const AdtDef as usize;
2069 *cache.borrow_mut().entry(addr).or_insert_with(|| {
2070 let ty::AdtDef { did, ref variants, ref flags, ref repr } = *self;
2072 let mut hasher = StableHasher::new();
2073 did.hash_stable(hcx, &mut hasher);
2074 variants.hash_stable(hcx, &mut hasher);
2075 flags.hash_stable(hcx, &mut hasher);
2076 repr.hash_stable(hcx, &mut hasher);
2082 hash.hash_stable(hcx, hasher);
2086 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
2093 impl Into<DataTypeKind> for AdtKind {
2094 fn into(self) -> DataTypeKind {
2096 AdtKind::Struct => DataTypeKind::Struct,
2097 AdtKind::Union => DataTypeKind::Union,
2098 AdtKind::Enum => DataTypeKind::Enum,
2104 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
2105 pub struct ReprFlags: u8 {
2106 const IS_C = 1 << 0;
2107 const IS_SIMD = 1 << 1;
2108 const IS_TRANSPARENT = 1 << 2;
2109 // Internal only for now. If true, don't reorder fields.
2110 const IS_LINEAR = 1 << 3;
2111 // If true, don't expose any niche to type's context.
2112 const HIDE_NICHE = 1 << 4;
2113 // Any of these flags being set prevent field reordering optimisation.
2114 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits |
2115 ReprFlags::IS_SIMD.bits |
2116 ReprFlags::IS_LINEAR.bits;
2120 /// Represents the repr options provided by the user,
2121 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
2122 pub struct ReprOptions {
2123 pub int: Option<attr::IntType>,
2124 pub align: Option<Align>,
2125 pub pack: Option<Align>,
2126 pub flags: ReprFlags,
2130 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
2131 let mut flags = ReprFlags::empty();
2132 let mut size = None;
2133 let mut max_align: Option<Align> = None;
2134 let mut min_pack: Option<Align> = None;
2135 for attr in tcx.get_attrs(did).iter() {
2136 for r in attr::find_repr_attrs(&tcx.sess, attr) {
2137 flags.insert(match r {
2138 attr::ReprC => ReprFlags::IS_C,
2139 attr::ReprPacked(pack) => {
2140 let pack = Align::from_bytes(pack as u64).unwrap();
2141 min_pack = Some(if let Some(min_pack) = min_pack {
2148 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
2149 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
2150 attr::ReprSimd => ReprFlags::IS_SIMD,
2151 attr::ReprInt(i) => {
2155 attr::ReprAlign(align) => {
2156 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
2163 // This is here instead of layout because the choice must make it into metadata.
2164 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
2165 flags.insert(ReprFlags::IS_LINEAR);
2167 ReprOptions { int: size, align: max_align, pack: min_pack, flags }
2171 pub fn simd(&self) -> bool {
2172 self.flags.contains(ReprFlags::IS_SIMD)
2175 pub fn c(&self) -> bool {
2176 self.flags.contains(ReprFlags::IS_C)
2179 pub fn packed(&self) -> bool {
2183 pub fn transparent(&self) -> bool {
2184 self.flags.contains(ReprFlags::IS_TRANSPARENT)
2187 pub fn linear(&self) -> bool {
2188 self.flags.contains(ReprFlags::IS_LINEAR)
2191 pub fn hide_niche(&self) -> bool {
2192 self.flags.contains(ReprFlags::HIDE_NICHE)
2195 /// Returns the discriminant type, given these `repr` options.
2196 /// This must only be called on enums!
2197 pub fn discr_type(&self) -> attr::IntType {
2198 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
2201 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
2202 /// layout" optimizations, such as representing `Foo<&T>` as a
2204 pub fn inhibit_enum_layout_opt(&self) -> bool {
2205 self.c() || self.int.is_some()
2208 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
2209 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
2210 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
2211 if let Some(pack) = self.pack {
2212 if pack.bytes() == 1 {
2216 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
2219 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
2220 pub fn inhibit_union_abi_opt(&self) -> bool {
2226 /// Creates a new `AdtDef`.
2231 variants: IndexVec<VariantIdx, VariantDef>,
2234 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
2235 let mut flags = AdtFlags::NO_ADT_FLAGS;
2237 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
2238 debug!("found non-exhaustive variant list for {:?}", did);
2239 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
2242 flags |= match kind {
2243 AdtKind::Enum => AdtFlags::IS_ENUM,
2244 AdtKind::Union => AdtFlags::IS_UNION,
2245 AdtKind::Struct => AdtFlags::IS_STRUCT,
2248 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
2249 flags |= AdtFlags::HAS_CTOR;
2252 let attrs = tcx.get_attrs(did);
2253 if tcx.sess.contains_name(&attrs, sym::fundamental) {
2254 flags |= AdtFlags::IS_FUNDAMENTAL;
2256 if Some(did) == tcx.lang_items().phantom_data() {
2257 flags |= AdtFlags::IS_PHANTOM_DATA;
2259 if Some(did) == tcx.lang_items().owned_box() {
2260 flags |= AdtFlags::IS_BOX;
2262 if Some(did) == tcx.lang_items().manually_drop() {
2263 flags |= AdtFlags::IS_MANUALLY_DROP;
2266 AdtDef { did, variants, flags, repr }
2269 /// Returns `true` if this is a struct.
2271 pub fn is_struct(&self) -> bool {
2272 self.flags.contains(AdtFlags::IS_STRUCT)
2275 /// Returns `true` if this is a union.
2277 pub fn is_union(&self) -> bool {
2278 self.flags.contains(AdtFlags::IS_UNION)
2281 /// Returns `true` if this is a enum.
2283 pub fn is_enum(&self) -> bool {
2284 self.flags.contains(AdtFlags::IS_ENUM)
2287 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
2289 pub fn is_variant_list_non_exhaustive(&self) -> bool {
2290 self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
2293 /// Returns the kind of the ADT.
2295 pub fn adt_kind(&self) -> AdtKind {
2298 } else if self.is_union() {
2305 /// Returns a description of this abstract data type.
2306 pub fn descr(&self) -> &'static str {
2307 match self.adt_kind() {
2308 AdtKind::Struct => "struct",
2309 AdtKind::Union => "union",
2310 AdtKind::Enum => "enum",
2314 /// Returns a description of a variant of this abstract data type.
2316 pub fn variant_descr(&self) -> &'static str {
2317 match self.adt_kind() {
2318 AdtKind::Struct => "struct",
2319 AdtKind::Union => "union",
2320 AdtKind::Enum => "variant",
2324 /// If this function returns `true`, it implies that `is_struct` must return `true`.
2326 pub fn has_ctor(&self) -> bool {
2327 self.flags.contains(AdtFlags::HAS_CTOR)
2330 /// Returns `true` if this type is `#[fundamental]` for the purposes
2331 /// of coherence checking.
2333 pub fn is_fundamental(&self) -> bool {
2334 self.flags.contains(AdtFlags::IS_FUNDAMENTAL)
2337 /// Returns `true` if this is `PhantomData<T>`.
2339 pub fn is_phantom_data(&self) -> bool {
2340 self.flags.contains(AdtFlags::IS_PHANTOM_DATA)
2343 /// Returns `true` if this is Box<T>.
2345 pub fn is_box(&self) -> bool {
2346 self.flags.contains(AdtFlags::IS_BOX)
2349 /// Returns `true` if this is `ManuallyDrop<T>`.
2351 pub fn is_manually_drop(&self) -> bool {
2352 self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
2355 /// Returns `true` if this type has a destructor.
2356 pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
2357 self.destructor(tcx).is_some()
2360 /// Asserts this is a struct or union and returns its unique variant.
2361 pub fn non_enum_variant(&self) -> &VariantDef {
2362 assert!(self.is_struct() || self.is_union());
2363 &self.variants[VariantIdx::new(0)]
2367 pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
2368 tcx.predicates_of(self.did)
2371 /// Returns an iterator over all fields contained
2374 pub fn all_fields(&self) -> impl Iterator<Item = &FieldDef> + Clone {
2375 self.variants.iter().flat_map(|v| v.fields.iter())
2378 /// Whether the ADT lacks fields. Note that this includes uninhabited enums,
2379 /// e.g., `enum Void {}` is considered payload free as well.
2380 pub fn is_payloadfree(&self) -> bool {
2381 self.variants.iter().all(|v| v.fields.is_empty())
2384 /// Return a `VariantDef` given a variant id.
2385 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
2386 self.variants.iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
2389 /// Return a `VariantDef` given a constructor id.
2390 pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
2393 .find(|v| v.ctor_def_id == Some(cid))
2394 .expect("variant_with_ctor_id: unknown variant")
2397 /// Return the index of `VariantDef` given a variant id.
2398 pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
2401 .find(|(_, v)| v.def_id == vid)
2402 .expect("variant_index_with_id: unknown variant")
2406 /// Return the index of `VariantDef` given a constructor id.
2407 pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
2410 .find(|(_, v)| v.ctor_def_id == Some(cid))
2411 .expect("variant_index_with_ctor_id: unknown variant")
2415 pub fn variant_of_res(&self, res: Res) -> &VariantDef {
2417 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
2418 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
2419 Res::Def(DefKind::Struct, _)
2420 | Res::Def(DefKind::Union, _)
2421 | Res::Def(DefKind::TyAlias, _)
2422 | Res::Def(DefKind::AssocTy, _)
2424 | Res::SelfCtor(..) => self.non_enum_variant(),
2425 _ => bug!("unexpected res {:?} in variant_of_res", res),
2430 pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
2431 assert!(self.is_enum());
2432 let param_env = tcx.param_env(expr_did);
2433 let repr_type = self.repr.discr_type();
2434 match tcx.const_eval_poly(expr_did) {
2436 let ty = repr_type.to_ty(tcx);
2437 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
2438 trace!("discriminants: {} ({:?})", b, repr_type);
2439 Some(Discr { val: b, ty })
2441 info!("invalid enum discriminant: {:#?}", val);
2442 crate::mir::interpret::struct_error(
2443 tcx.at(tcx.def_span(expr_did)),
2444 "constant evaluation of enum discriminant resulted in non-integer",
2451 let msg = match err {
2452 ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => {
2453 "enum discriminant evaluation failed"
2455 ErrorHandled::TooGeneric => "enum discriminant depends on generics",
2457 tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg);
2464 pub fn discriminants(
2467 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
2468 assert!(self.is_enum());
2469 let repr_type = self.repr.discr_type();
2470 let initial = repr_type.initial_discriminant(tcx);
2471 let mut prev_discr = None::<Discr<'tcx>>;
2472 self.variants.iter_enumerated().map(move |(i, v)| {
2473 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
2474 if let VariantDiscr::Explicit(expr_did) = v.discr {
2475 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
2479 prev_discr = Some(discr);
2486 pub fn variant_range(&self) -> Range<VariantIdx> {
2487 VariantIdx::new(0)..VariantIdx::new(self.variants.len())
2490 /// Computes the discriminant value used by a specific variant.
2491 /// Unlike `discriminants`, this is (amortized) constant-time,
2492 /// only doing at most one query for evaluating an explicit
2493 /// discriminant (the last one before the requested variant),
2494 /// assuming there are no constant-evaluation errors there.
2496 pub fn discriminant_for_variant(
2499 variant_index: VariantIdx,
2501 assert!(self.is_enum());
2502 let (val, offset) = self.discriminant_def_for_variant(variant_index);
2503 let explicit_value = val
2504 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
2505 .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx));
2506 explicit_value.checked_add(tcx, offset as u128).0
2509 /// Yields a `DefId` for the discriminant and an offset to add to it
2510 /// Alternatively, if there is no explicit discriminant, returns the
2511 /// inferred discriminant directly.
2512 pub fn discriminant_def_for_variant(&self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
2513 assert!(!self.variants.is_empty());
2514 let mut explicit_index = variant_index.as_u32();
2517 match self.variants[VariantIdx::from_u32(explicit_index)].discr {
2518 ty::VariantDiscr::Relative(0) => {
2522 ty::VariantDiscr::Relative(distance) => {
2523 explicit_index -= distance;
2525 ty::VariantDiscr::Explicit(did) => {
2526 expr_did = Some(did);
2531 (expr_did, variant_index.as_u32() - explicit_index)
2534 pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
2535 tcx.adt_destructor(self.did)
2538 /// Returns a list of types such that `Self: Sized` if and only
2539 /// if that type is `Sized`, or `TyErr` if this type is recursive.
2541 /// Oddly enough, checking that the sized-constraint is `Sized` is
2542 /// actually more expressive than checking all members:
2543 /// the `Sized` trait is inductive, so an associated type that references
2544 /// `Self` would prevent its containing ADT from being `Sized`.
2546 /// Due to normalization being eager, this applies even if
2547 /// the associated type is behind a pointer (e.g., issue #31299).
2548 pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] {
2549 tcx.adt_sized_constraint(self.did).0
2553 impl<'tcx> FieldDef {
2554 /// Returns the type of this field. The `subst` is typically obtained
2555 /// via the second field of `TyKind::AdtDef`.
2556 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
2557 tcx.type_of(self.did).subst(tcx, subst)
2561 /// Represents the various closure traits in the language. This
2562 /// will determine the type of the environment (`self`, in the
2563 /// desugaring) argument that the closure expects.
2565 /// You can get the environment type of a closure using
2566 /// `tcx.closure_env_ty()`.
2567 #[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
2568 #[derive(HashStable)]
2569 pub enum ClosureKind {
2570 // Warning: Ordering is significant here! The ordering is chosen
2571 // because the trait Fn is a subtrait of FnMut and so in turn, and
2572 // hence we order it so that Fn < FnMut < FnOnce.
2578 impl<'tcx> ClosureKind {
2579 // This is the initial value used when doing upvar inference.
2580 pub const LATTICE_BOTTOM: ClosureKind = ClosureKind::Fn;
2582 pub fn trait_did(&self, tcx: TyCtxt<'tcx>) -> DefId {
2584 ClosureKind::Fn => tcx.require_lang_item(LangItem::Fn, None),
2585 ClosureKind::FnMut => tcx.require_lang_item(LangItem::FnMut, None),
2586 ClosureKind::FnOnce => tcx.require_lang_item(LangItem::FnOnce, None),
2590 /// Returns `true` if a type that impls this closure kind
2591 /// must also implement `other`.
2592 pub fn extends(self, other: ty::ClosureKind) -> bool {
2595 (ClosureKind::Fn, ClosureKind::Fn)
2596 | (ClosureKind::Fn, ClosureKind::FnMut)
2597 | (ClosureKind::Fn, ClosureKind::FnOnce)
2598 | (ClosureKind::FnMut, ClosureKind::FnMut)
2599 | (ClosureKind::FnMut, ClosureKind::FnOnce)
2600 | (ClosureKind::FnOnce, ClosureKind::FnOnce)
2604 /// Returns the representative scalar type for this closure kind.
2605 /// See `TyS::to_opt_closure_kind` for more details.
2606 pub fn to_ty(self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
2608 ty::ClosureKind::Fn => tcx.types.i8,
2609 ty::ClosureKind::FnMut => tcx.types.i16,
2610 ty::ClosureKind::FnOnce => tcx.types.i32,
2616 pub fn from_mutbl(m: hir::Mutability) -> BorrowKind {
2618 hir::Mutability::Mut => MutBorrow,
2619 hir::Mutability::Not => ImmBorrow,
2623 /// Returns a mutability `m` such that an `&m T` pointer could be used to obtain this borrow
2624 /// kind. Because borrow kinds are richer than mutabilities, we sometimes have to pick a
2625 /// mutability that is stronger than necessary so that it at least *would permit* the borrow in
2627 pub fn to_mutbl_lossy(self) -> hir::Mutability {
2629 MutBorrow => hir::Mutability::Mut,
2630 ImmBorrow => hir::Mutability::Not,
2632 // We have no type corresponding to a unique imm borrow, so
2633 // use `&mut`. It gives all the capabilities of an `&uniq`
2634 // and hence is a safe "over approximation".
2635 UniqueImmBorrow => hir::Mutability::Mut,
2639 pub fn to_user_str(&self) -> &'static str {
2641 MutBorrow => "mutable",
2642 ImmBorrow => "immutable",
2643 UniqueImmBorrow => "uniquely immutable",
2648 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
2650 #[derive(Debug, PartialEq, Eq)]
2651 pub enum ImplOverlapKind {
2652 /// These impls are always allowed to overlap.
2654 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
2657 /// These impls are allowed to overlap, but that raises
2658 /// an issue #33140 future-compatibility warning.
2660 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
2661 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
2663 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
2664 /// that difference, making what reduces to the following set of impls:
2668 /// impl Trait for dyn Send + Sync {}
2669 /// impl Trait for dyn Sync + Send {}
2672 /// Obviously, once we made these types be identical, that code causes a coherence
2673 /// error and a fairly big headache for us. However, luckily for us, the trait
2674 /// `Trait` used in this case is basically a marker trait, and therefore having
2675 /// overlapping impls for it is sound.
2677 /// To handle this, we basically regard the trait as a marker trait, with an additional
2678 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
2679 /// it has the following restrictions:
2681 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
2683 /// 2. The trait-ref of both impls must be equal.
2684 /// 3. The trait-ref of both impls must be a trait object type consisting only of
2686 /// 4. Neither of the impls can have any where-clauses.
2688 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
2692 impl<'tcx> TyCtxt<'tcx> {
2693 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
2694 self.typeck(self.hir().body_owner_def_id(body))
2697 /// Returns an iterator of the `DefId`s for all body-owners in this
2698 /// crate. If you would prefer to iterate over the bodies
2699 /// themselves, you can do `self.hir().krate().body_ids.iter()`.
2700 pub fn body_owners(self) -> impl Iterator<Item = LocalDefId> + Captures<'tcx> + 'tcx {
2705 .map(move |&body_id| self.hir().body_owner_def_id(body_id))
2708 pub fn par_body_owners<F: Fn(LocalDefId) + sync::Sync + sync::Send>(self, f: F) {
2709 par_iter(&self.hir().krate().body_ids)
2710 .for_each(|&body_id| f(self.hir().body_owner_def_id(body_id)));
2713 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
2714 self.associated_items(id)
2715 .in_definition_order()
2716 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
2719 fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
2720 self.hir().get_if_local(def_id).and_then(|node| node.ident())
2723 fn item_name_from_def_id(self, def_id: DefId) -> Option<Symbol> {
2724 if def_id.index == CRATE_DEF_INDEX {
2725 Some(self.original_crate_name(def_id.krate))
2727 let def_key = self.def_key(def_id);
2728 match def_key.disambiguated_data.data {
2729 // The name of a constructor is that of its parent.
2730 rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId {
2731 krate: def_id.krate,
2732 index: def_key.parent.unwrap(),
2734 _ => def_key.disambiguated_data.data.get_opt_name(),
2739 /// Look up the name of an item across crates. This does not look at HIR.
2741 /// When possible, this function should be used for cross-crate lookups over
2742 /// [`opt_item_name`] to avoid invalidating the incremental cache. If you
2743 /// need to handle items without a name, or HIR items that will not be
2744 /// serialized cross-crate, or if you need the span of the item, use
2745 /// [`opt_item_name`] instead.
2747 /// [`opt_item_name`]: Self::opt_item_name
2748 pub fn item_name(self, id: DefId) -> Symbol {
2749 // Look at cross-crate items first to avoid invalidating the incremental cache
2750 // unless we have to.
2751 self.item_name_from_def_id(id).unwrap_or_else(|| {
2752 bug!("item_name: no name for {:?}", self.def_path(id));
2756 /// Look up the name and span of an item or [`Node`].
2758 /// See [`item_name`][Self::item_name] for more information.
2759 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
2760 // Look at the HIR first so the span will be correct if this is a local item.
2761 self.item_name_from_hir(def_id)
2762 .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span))
2765 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
2766 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2767 Some(self.associated_item(def_id))
2773 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
2774 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
2777 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
2778 variant.fields.iter().position(|field| self.hygienic_eq(ident, field.ident, variant.def_id))
2781 /// Returns `true` if the impls are the same polarity and the trait either
2782 /// has no items or is annotated `#[marker]` and prevents item overrides.
2783 pub fn impls_are_allowed_to_overlap(
2787 ) -> Option<ImplOverlapKind> {
2788 // If either trait impl references an error, they're allowed to overlap,
2789 // as one of them essentially doesn't exist.
2790 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2791 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2793 return Some(ImplOverlapKind::Permitted { marker: false });
2796 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2797 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2798 // `#[rustc_reservation_impl]` impls don't overlap with anything
2800 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2803 return Some(ImplOverlapKind::Permitted { marker: false });
2805 (ImplPolarity::Positive, ImplPolarity::Negative)
2806 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2807 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2809 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2814 (ImplPolarity::Positive, ImplPolarity::Positive)
2815 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2818 let is_marker_overlap = {
2819 let is_marker_impl = |def_id: DefId| -> bool {
2820 let trait_ref = self.impl_trait_ref(def_id);
2821 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2823 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2826 if is_marker_overlap {
2828 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2831 Some(ImplOverlapKind::Permitted { marker: true })
2833 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2834 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2835 if self_ty1 == self_ty2 {
2837 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2840 return Some(ImplOverlapKind::Issue33140);
2843 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2844 def_id1, def_id2, self_ty1, self_ty2
2850 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2855 /// Returns `ty::VariantDef` if `res` refers to a struct,
2856 /// or variant or their constructors, panics otherwise.
2857 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2859 Res::Def(DefKind::Variant, did) => {
2860 let enum_did = self.parent(did).unwrap();
2861 self.adt_def(enum_did).variant_with_id(did)
2863 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2864 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2865 let variant_did = self.parent(variant_ctor_did).unwrap();
2866 let enum_did = self.parent(variant_did).unwrap();
2867 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2869 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2870 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2871 self.adt_def(struct_did).non_enum_variant()
2873 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2877 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2878 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2880 ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
2883 | DefKind::AssocConst
2885 | DefKind::AnonConst => self.mir_for_ctfe_opt_const_arg(def),
2886 // If the caller wants `mir_for_ctfe` of a function they should not be using
2887 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2889 assert_eq!(def.const_param_did, None);
2890 self.optimized_mir(def.did)
2893 ty::InstanceDef::VtableShim(..)
2894 | ty::InstanceDef::ReifyShim(..)
2895 | ty::InstanceDef::Intrinsic(..)
2896 | ty::InstanceDef::FnPtrShim(..)
2897 | ty::InstanceDef::Virtual(..)
2898 | ty::InstanceDef::ClosureOnceShim { .. }
2899 | ty::InstanceDef::DropGlue(..)
2900 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2904 /// Gets the attributes of a definition.
2905 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
2906 if let Some(did) = did.as_local() {
2907 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2909 self.item_attrs(did)
2913 /// Determines whether an item is annotated with an attribute.
2914 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2915 self.sess.contains_name(&self.get_attrs(did), attr)
2918 /// Returns `true` if this is an `auto trait`.
2919 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2920 self.trait_def(trait_def_id).has_auto_impl
2923 /// Returns layout of a generator. Layout might be unavailable if the
2924 /// generator is tainted by errors.
2925 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2926 self.optimized_mir(def_id).generator_layout()
2929 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2930 /// If it implements no trait, returns `None`.
2931 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2932 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2935 /// If the given defid describes a method belonging to an impl, returns the
2936 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2937 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2938 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
2939 TraitContainer(_) => None,
2940 ImplContainer(def_id) => Some(def_id),
2944 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2945 /// with the name of the crate containing the impl.
2946 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2947 if let Some(impl_did) = impl_did.as_local() {
2948 let hir_id = self.hir().local_def_id_to_hir_id(impl_did);
2949 Ok(self.hir().span(hir_id))
2951 Err(self.crate_name(impl_did.krate))
2955 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2956 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2957 /// definition's parent/scope to perform comparison.
2958 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2959 // We could use `Ident::eq` here, but we deliberately don't. The name
2960 // comparison fails frequently, and we want to avoid the expensive
2961 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2962 use_name.name == def_name.name
2966 .hygienic_eq(def_name.span.ctxt(), self.expansion_that_defined(def_parent_def_id))
2969 pub fn expansion_that_defined(self, scope: DefId) -> ExpnId {
2970 match scope.as_local() {
2971 // Parsing and expansion aren't incremental, so we don't
2972 // need to go through a query for the same-crate case.
2973 Some(scope) => self.hir().definitions().expansion_that_defined(scope),
2974 None => self.expn_that_defined(scope),
2978 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2979 ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope));
2983 pub fn adjust_ident_and_get_scope(
2988 ) -> (Ident, DefId) {
2990 match ident.span.normalize_to_macros_2_0_and_adjust(self.expansion_that_defined(scope))
2992 Some(actual_expansion) => {
2993 self.hir().definitions().parent_module_of_macro_def(actual_expansion)
2995 None => self.parent_module(block).to_def_id(),
3000 pub fn is_object_safe(self, key: DefId) -> bool {
3001 self.object_safety_violations(key).is_empty()
3005 #[derive(Clone, HashStable, Debug)]
3006 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
3008 /// Yields the parent function's `DefId` if `def_id` is an `impl Trait` definition.
3009 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
3010 if let Some(def_id) = def_id.as_local() {
3011 if let Node::Item(item) = tcx.hir().get(tcx.hir().local_def_id_to_hir_id(def_id)) {
3012 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
3013 return opaque_ty.impl_trait_fn;
3020 pub fn int_ty(ity: ast::IntTy) -> IntTy {
3022 ast::IntTy::Isize => IntTy::Isize,
3023 ast::IntTy::I8 => IntTy::I8,
3024 ast::IntTy::I16 => IntTy::I16,
3025 ast::IntTy::I32 => IntTy::I32,
3026 ast::IntTy::I64 => IntTy::I64,
3027 ast::IntTy::I128 => IntTy::I128,
3031 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
3033 ast::UintTy::Usize => UintTy::Usize,
3034 ast::UintTy::U8 => UintTy::U8,
3035 ast::UintTy::U16 => UintTy::U16,
3036 ast::UintTy::U32 => UintTy::U32,
3037 ast::UintTy::U64 => UintTy::U64,
3038 ast::UintTy::U128 => UintTy::U128,
3042 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
3044 ast::FloatTy::F32 => FloatTy::F32,
3045 ast::FloatTy::F64 => FloatTy::F64,
3049 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
3051 IntTy::Isize => ast::IntTy::Isize,
3052 IntTy::I8 => ast::IntTy::I8,
3053 IntTy::I16 => ast::IntTy::I16,
3054 IntTy::I32 => ast::IntTy::I32,
3055 IntTy::I64 => ast::IntTy::I64,
3056 IntTy::I128 => ast::IntTy::I128,
3060 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
3062 UintTy::Usize => ast::UintTy::Usize,
3063 UintTy::U8 => ast::UintTy::U8,
3064 UintTy::U16 => ast::UintTy::U16,
3065 UintTy::U32 => ast::UintTy::U32,
3066 UintTy::U64 => ast::UintTy::U64,
3067 UintTy::U128 => ast::UintTy::U128,
3071 pub fn provide(providers: &mut ty::query::Providers) {
3072 context::provide(providers);
3073 erase_regions::provide(providers);
3074 layout::provide(providers);
3075 util::provide(providers);
3076 print::provide(providers);
3077 super::util::bug::provide(providers);
3078 *providers = ty::query::Providers {
3079 trait_impls_of: trait_def::trait_impls_of_provider,
3080 all_local_trait_impls: trait_def::all_local_trait_impls,
3081 type_uninhabited_from: inhabitedness::type_uninhabited_from,
3086 /// A map for the local crate mapping each type to a vector of its
3087 /// inherent impls. This is not meant to be used outside of coherence;
3088 /// rather, you should request the vector for a specific type via
3089 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
3090 /// (constructing this map requires touching the entire crate).
3091 #[derive(Clone, Debug, Default, HashStable)]
3092 pub struct CrateInherentImpls {
3093 pub inherent_impls: DefIdMap<Vec<DefId>>,
3096 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
3097 pub struct SymbolName<'tcx> {
3098 /// `&str` gives a consistent ordering, which ensures reproducible builds.
3099 pub name: &'tcx str,
3102 impl<'tcx> SymbolName<'tcx> {
3103 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
3105 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
3110 impl<'tcx> fmt::Display for SymbolName<'tcx> {
3111 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3112 fmt::Display::fmt(&self.name, fmt)
3116 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
3117 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
3118 fmt::Display::fmt(&self.name, fmt)