mod.rs source code [rust/compiler/rustc_middle/src/ty/mod.rs]

1	//! Defines how the compiler represents types internally.
2	//!
3	//! Two important entities in this module are:
4	//!
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.
7	//!
8	//! For more information, see ["The `ty` module: representing types"] in the rustc-dev-guide.
9	//!
10	//! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html
11
12	#![allow(rustc::usage_of_ty_tykind)]
13
14	use std::assert_matches::assert_matches;
15	use std::fmt::Debug;
16	use std::hash::{Hash, Hasher};
17	use std::marker::PhantomData;
18	use std::num::NonZero;
19	use std::ptr::NonNull;
20	use std::{fmt, str};
21
22	pub use adt::*;
23	pub use assoc::*;
24	pub use generic_args::{GenericArgKind, TermKind, *};
25	pub use generics::*;
26	pub use intrinsic::IntrinsicDef;
27	use rustc_abi::{Align, FieldIdx, Integer, IntegerType, ReprFlags, ReprOptions, VariantIdx};
28	use rustc_ast::expand::StrippedCfgItem;
29	use rustc_ast::node_id::NodeMap;
30	pub use rustc_ast_ir::{Movability, Mutability, try_visit};
31	use rustc_attr_data_structures::AttributeKind;
32	use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
33	use rustc_data_structures::intern::Interned;
34	use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
35	use rustc_data_structures::steal::Steal;
36	use rustc_data_structures::unord::UnordMap;
37	use rustc_errors::{Diag, ErrorGuaranteed};
38	use rustc_hir::LangItem;
39	use rustc_hir::def::{CtorKind, CtorOf, DefKind, DocLinkResMap, LifetimeRes, Res};
40	use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LocalDefIdMap};
41	use rustc_index::IndexVec;
42	use rustc_macros::{
43	Decodable, Encodable, HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable,
44	extension,
45	};
46	use rustc_query_system::ich::StableHashingContext;
47	use rustc_serialize::{Decodable, Encodable};
48	use rustc_session::lint::LintBuffer;
49	pub use rustc_session::lint::RegisteredTools;
50	use rustc_span::hygiene::MacroKind;
51	use rustc_span::{ExpnId, ExpnKind, Ident, Span, Symbol, kw, sym};
52	pub use rustc_type_ir::relate::VarianceDiagInfo;
53	pub use rustc_type_ir::*;
54	use tracing::{debug, instrument};
55	pub use vtable::*;
56	use {rustc_ast as ast, rustc_attr_data_structures as attr, rustc_hir as hir};
57
58	pub use self::closure::{
59	BorrowKind, CAPTURE_STRUCT_LOCAL, CaptureInfo, CapturedPlace, ClosureTypeInfo,
60	MinCaptureInformationMap, MinCaptureList, RootVariableMinCaptureList, UpvarCapture, UpvarId,
61	UpvarPath, analyze_coroutine_closure_captures, is_ancestor_or_same_capture,
62	place_to_string_for_capture,
63	};
64	pub use self::consts::{
65	Const, ConstInt, ConstKind, Expr, ExprKind, ScalarInt, UnevaluatedConst, ValTree, ValTreeKind,
66	Value,
67	};
68	pub use self::context::{
69	CtxtInterners, CurrentGcx, DeducedParamAttrs, Feed, FreeRegionInfo, GlobalCtxt, Lift, TyCtxt,
70	TyCtxtFeed, tls,
71	};
72	pub use self::fold::*;
73	pub use self::instance::{Instance, InstanceKind, ReifyReason, ShortInstance, UnusedGenericParams};
74	pub use self::list::{List, ListWithCachedTypeInfo};
75	pub use self::opaque_types::OpaqueTypeKey;
76	pub use self::parameterized::ParameterizedOverTcx;
77	pub use self::pattern::{Pattern, PatternKind};
78	pub use self::predicate::{
79	AliasTerm, Clause, ClauseKind, CoercePredicate, ExistentialPredicate,
80	ExistentialPredicateStableCmpExt, ExistentialProjection, ExistentialTraitRef,
81	HostEffectPredicate, NormalizesTo, OutlivesPredicate, PolyCoercePredicate,
82	PolyExistentialPredicate, PolyExistentialProjection, PolyExistentialTraitRef,
83	PolyProjectionPredicate, PolyRegionOutlivesPredicate, PolySubtypePredicate, PolyTraitPredicate,
84	PolyTraitRef, PolyTypeOutlivesPredicate, Predicate, PredicateKind, ProjectionPredicate,
85	RegionOutlivesPredicate, SubtypePredicate, TraitPredicate, TraitRef, TypeOutlivesPredicate,
86	};
87	pub use self::region::{
88	BoundRegion, BoundRegionKind, EarlyParamRegion, LateParamRegion, LateParamRegionKind, Region,
89	RegionKind, RegionVid,
90	};
91	pub use self::rvalue_scopes::RvalueScopes;
92	pub use self::sty::{
93	AliasTy, Article, Binder, BoundTy, BoundTyKind, BoundVariableKind, CanonicalPolyFnSig,
94	CoroutineArgsExt, EarlyBinder, FnSig, InlineConstArgs, InlineConstArgsParts, ParamConst,
95	ParamTy, PolyFnSig, TyKind, TypeAndMut, TypingMode, UpvarArgs,
96	};
97	pub use self::trait_def::TraitDef;
98	pub use self::typeck_results::{
99	CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, IsIdentity,
100	Rust2024IncompatiblePatInfo, TypeckResults, UserType, UserTypeAnnotationIndex, UserTypeKind,
101	};
102	pub use self::visit::*;
103	use crate::error::{OpaqueHiddenTypeMismatch, TypeMismatchReason};
104	use crate::metadata::ModChild;
105	use crate::middle::privacy::EffectiveVisibilities;
106	use crate::mir::{Body, CoroutineLayout};
107	use crate::query::{IntoQueryParam, Providers};
108	use crate::ty;
109	use crate::ty::codec::{TyDecoder, TyEncoder};
110	pub use crate::ty::diagnostics::*;
111	use crate::ty::fast_reject::SimplifiedType;
112	use crate::ty::util::Discr;
113
114	pub mod abstract_const;
115	pub mod adjustment;
116	pub mod cast;
117	pub mod codec;
118	pub mod error;
119	pub mod fast_reject;
120	pub mod flags;
121	pub mod inhabitedness;
122	pub mod layout;
123	pub mod normalize_erasing_regions;
124	pub mod pattern;
125	pub mod print;
126	pub mod relate;
127	pub mod significant_drop_order;
128	pub mod trait_def;
129	pub mod util;
130	pub mod vtable;
131	pub mod walk;
132
133	mod adt;
134	mod assoc;
135	mod closure;
136	mod consts;
137	mod context;
138	mod diagnostics;
139	mod elaborate_impl;
140	mod erase_regions;
141	mod fold;
142	mod generic_args;
143	mod generics;
144	mod impls_ty;
145	mod instance;
146	mod intrinsic;
147	mod list;
148	mod opaque_types;
149	mod parameterized;
150	mod predicate;
151	mod region;
152	mod rvalue_scopes;
153	mod structural_impls;
154	#[allow(hidden_glob_reexports)]
155	mod sty;
156	mod typeck_results;
157	mod visit;
158
159	// Data types
160
161	pub struct ResolverOutputs {
162	pub global_ctxt: ResolverGlobalCtxt,
163	pub ast_lowering: ResolverAstLowering,
164	}
165
166	#[derive(Debug)]
167	pub struct ResolverGlobalCtxt {
168	pub visibilities_for_hashing: Vec<(LocalDefId, Visibility)>,
169	/// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
170	pub expn_that_defined: FxHashMap<LocalDefId, ExpnId>,
171	pub effective_visibilities: EffectiveVisibilities,
172	pub extern_crate_map: UnordMap<LocalDefId, CrateNum>,
173	pub maybe_unused_trait_imports: FxIndexSet<LocalDefId>,
174	pub module_children: LocalDefIdMap<Vec<ModChild>>,
175	pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
176	pub main_def: Option<MainDefinition>,
177	pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
178	/// A list of proc macro LocalDefIds, written out in the order in which
179	/// they are declared in the static array generated by proc_macro_harness.
180	pub proc_macros: Vec<LocalDefId>,
181	/// Mapping from ident span to path span for paths that don't exist as written, but that
182	/// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
183	pub confused_type_with_std_module: FxIndexMap<Span, Span>,
184	pub doc_link_resolutions: FxIndexMap<LocalDefId, DocLinkResMap>,
185	pub doc_link_traits_in_scope: FxIndexMap<LocalDefId, Vec<DefId>>,
186	pub all_macro_rules: FxHashSet<Symbol>,
187	pub stripped_cfg_items: Steal<Vec<StrippedCfgItem>>,
188	}
189
190	/// Resolutions that should only be used for lowering.
191	/// This struct is meant to be consumed by lowering.
192	#[derive(Debug)]
193	pub struct ResolverAstLowering {
194	pub legacy_const_generic_args: FxHashMap<DefId, Option<Vec<usize>>>,
195
196	/// Resolutions for nodes that have a single resolution.
197	pub partial_res_map: NodeMap<hir::def::PartialRes>,
198	/// Resolutions for import nodes, which have multiple resolutions in different namespaces.
199	pub import_res_map: NodeMap<hir::def::PerNS<Option<Res<ast::NodeId>>>>,
200	/// Resolutions for labels (node IDs of their corresponding blocks or loops).
201	pub label_res_map: NodeMap<ast::NodeId>,
202	/// Resolutions for lifetimes.
203	pub lifetimes_res_map: NodeMap<LifetimeRes>,
204	/// Lifetime parameters that lowering will have to introduce.
205	pub extra_lifetime_params_map: NodeMap<Vec<(Ident, ast::NodeId, LifetimeRes)>>,
206
207	pub next_node_id: ast::NodeId,
208
209	pub node_id_to_def_id: NodeMap<LocalDefId>,
210
211	pub trait_map: NodeMap<Vec<hir::TraitCandidate>>,
212	/// List functions and methods for which lifetime elision was successful.
213	pub lifetime_elision_allowed: FxHashSet<ast::NodeId>,
214
215	/// Lints that were emitted by the resolver and early lints.
216	pub lint_buffer: Steal<LintBuffer>,
217
218	/// Information about functions signatures for delegation items expansion
219	pub delegation_fn_sigs: LocalDefIdMap<DelegationFnSig>,
220	}
221
222	#[derive(Debug)]
223	pub struct DelegationFnSig {
224	pub header: ast::FnHeader,
225	pub param_count: usize,
226	pub has_self: bool,
227	pub c_variadic: bool,
228	pub target_feature: bool,
229	}
230
231	#[derive(Clone, Copy, Debug)]
232	pub struct MainDefinition {
233	pub res: Res<ast::NodeId>,
234	pub is_import: bool,
235	pub span: Span,
236	}
237
238	impl MainDefinition {
239	pub fn opt_fn_def_id(self) -> Option<DefId> {
240	if let Res::Def(DefKind::Fn, def_id: DefId) = self.res { Some(def_id) } else { None }
241	}
242	}
243
244	/// The "header" of an impl is everything outside the body: a Self type, a trait
245	/// ref (in the case of a trait impl), and a set of predicates (from the
246	/// bounds / where-clauses).
247	#[derive(Clone, Debug, TypeFoldable, TypeVisitable)]
248	pub struct ImplHeader<'tcx> {
249	pub impl_def_id: DefId,
250	pub impl_args: ty::GenericArgsRef<'tcx>,
251	pub self_ty: Ty<'tcx>,
252	pub trait_ref: Option<TraitRef<'tcx>>,
253	pub predicates: Vec<Predicate<'tcx>>,
254	}
255
256	#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
257	pub struct ImplTraitHeader<'tcx> {
258	pub trait_ref: ty::EarlyBinder<'tcx, ty::TraitRef<'tcx>>,
259	pub polarity: ImplPolarity,
260	pub safety: hir::Safety,
261	pub constness: hir::Constness,
262	}
263
264	#[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable)]
265	pub enum ImplSubject<'tcx> {
266	Trait(TraitRef<'tcx>),
267	Inherent(Ty<'tcx>),
268	}
269
270	#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable, Debug)]
271	#[derive(TypeFoldable, TypeVisitable)]
272	pub enum Asyncness {
273	Yes,
274	No,
275	}
276
277	impl Asyncness {
278	pub fn is_async(self) -> bool {
279	matches!(self, Asyncness::Yes)
280	}
281	}
282
283	#[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, Encodable, Decodable, HashStable)]
284	pub enum Visibility<Id = LocalDefId> {
285	/// Visible everywhere (including in other crates).
286	Public,
287	/// Visible only in the given crate-local module.
288	Restricted(Id),
289	}
290
291	impl Visibility {
292	pub fn to_string(self, def_id: LocalDefId, tcx: TyCtxt<'_>) -> String {
293	match self {
294	ty::Visibility::Restricted(restricted_id: LocalDefId) => {
295	if restricted_id.is_top_level_module() {
296	"pub(crate)".to_string()
297	} else if restricted_id == tcx.parent_module_from_def_id(def_id).to_local_def_id() {
298	"pub(self)".to_string()
299	} else {
300	format!("pub({})", tcx.item_name(restricted_id.to_def_id()))
301	}
302	}
303	ty::Visibility::Public => "pub".to_string(),
304	}
305	}
306	}
307
308	#[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
309	#[derive(TypeFoldable, TypeVisitable)]
310	pub struct ClosureSizeProfileData<'tcx> {
311	/// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
312	pub before_feature_tys: Ty<'tcx>,
313	/// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
314	pub after_feature_tys: Ty<'tcx>,
315	}
316
317	impl TyCtxt<'_> {
318	#[inline]
319	pub fn opt_parent(self, id: DefId) -> Option<DefId> {
320	self.def_key(id).parent.map(\|index\| DefId { index, ..id })
321	}
322
323	#[inline]
324	#[track_caller]
325	pub fn parent(self, id: DefId) -> DefId {
326	match self.opt_parent(id) {
327	Some(id) => id,
328	// not `unwrap_or_else` to avoid breaking caller tracking
329	None => bug!("{id:?} doesn't have a parent"),
330	}
331	}
332
333	#[inline]
334	#[track_caller]
335	pub fn opt_local_parent(self, id: LocalDefId) -> Option<LocalDefId> {
336	self.opt_parent(id.to_def_id()).map(DefId::expect_local)
337	}
338
339	#[inline]
340	#[track_caller]
341	pub fn local_parent(self, id: impl Into<LocalDefId>) -> LocalDefId {
342	self.parent(id.into().to_def_id()).expect_local()
343	}
344
345	pub fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
346	if descendant.krate != ancestor.krate {
347	return `false`;
348	}
349
350	while descendant != ancestor {
351	match self.opt_parent(descendant) {
352	Some(parent) => descendant = parent,
353	None => return `false`,
354	}
355	}
356	`true`
357	}
358	}
359
360	impl<Id> Visibility<Id> {
361	pub fn is_public(self) -> bool {
362	matches!(self, Visibility::Public)
363	}
364
365	pub fn map_id<OutId>(self, f: impl FnOnce(Id) -> OutId) -> Visibility<OutId> {
366	match self {
367	Visibility::Public => Visibility::Public,
368	Visibility::Restricted(id: Id) => Visibility::Restricted(f(id)),
369	}
370	}
371	}
372
373	impl<Id: Into<DefId>> Visibility<Id> {
374	pub fn to_def_id(self) -> Visibility<DefId> {
375	self.map_id(Into::into)
376	}
377
378	/// Returns `true` if an item with this visibility is accessible from the given module.
379	pub fn is_accessible_from(self, module: impl Into<DefId>, tcx: TyCtxt<'_>) -> bool {
380	match self {
381	// Public items are visible everywhere.
382	Visibility::Public => `true`,
383	Visibility::Restricted(id: Id) => tcx.is_descendant_of(descendant:module.into(), ancestor:id.into()),
384	}
385	}
386
387	/// Returns `true` if this visibility is at least as accessible as the given visibility
388	pub fn is_at_least(self, vis: Visibility<impl Into<DefId>>, tcx: TyCtxt<'_>) -> bool {
389	match vis {
390	Visibility::Public => self.is_public(),
391	Visibility::Restricted(id: impl Into) => self.is_accessible_from(module:id, tcx),
392	}
393	}
394	}
395
396	impl Visibility<DefId> {
397	pub fn expect_local(self) -> Visibility {
398	self.map_id(\|id: DefId\| id.expect_local())
399	}
400
401	/// Returns `true` if this item is visible anywhere in the local crate.
402	pub fn is_visible_locally(self) -> bool {
403	match self {
404	Visibility::Public => `true`,
405	Visibility::Restricted(def_id: DefId) => def_id.is_local(),
406	}
407	}
408	}
409
410	/// The crate variances map is computed during typeck and contains the
411	/// variance of every item in the local crate. You should not use it
412	/// directly, because to do so will make your pass dependent on the
413	/// HIR of every item in the local crate. Instead, use
414	/// `tcx.variances_of()` to get the variance for a particular
415	/// item.
416	#[derive(HashStable, Debug)]
417	pub struct CrateVariancesMap<'tcx> {
418	/// For each item with generics, maps to a vector of the variance
419	/// of its generics. If an item has no generics, it will have no
420	/// entry.
421	pub variances: DefIdMap<&'tcx [ty::Variance]>,
422	}
423
424	// Contains information needed to resolve types and (in the future) look up
425	// the types of AST nodes.
426	#[derive(Copy, Clone, PartialEq, Eq, Hash)]
427	pub struct CReaderCacheKey {
428	pub cnum: Option<CrateNum>,
429	pub pos: usize,
430	}
431
432	/// Use this rather than `TyKind`, whenever possible.
433	#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable)]
434	#[rustc_diagnostic_item = "Ty"]
435	#[rustc_pass_by_value]
436	pub struct Ty<'tcx>(Interned<'tcx, WithCachedTypeInfo<TyKind<'tcx>>>);
437
438	impl<'tcx> rustc_type_ir::inherent::IntoKind for Ty<'tcx> {
439	type Kind = TyKind<'tcx>;
440
441	fn kind(self) -> TyKind<'tcx> {
442	*self.kind()
443	}
444	}
445
446	impl<'tcx> rustc_type_ir::Flags for Ty<'tcx> {
447	fn flags(&self) -> TypeFlags {
448	self.0.flags
449	}
450
451	fn outer_exclusive_binder(&self) -> DebruijnIndex {
452	self.0.outer_exclusive_binder
453	}
454	}
455
456	impl EarlyParamRegion {
457	/// Does this early bound region have a name? Early bound regions normally
458	/// always have names except when using anonymous lifetimes (`'_`).
459	pub fn has_name(&self) -> bool {
460	self.name != kw::UnderscoreLifetime
461	}
462	}
463
464	/// The crate outlives map is computed during typeck and contains the
465	/// outlives of every item in the local crate. You should not use it
466	/// directly, because to do so will make your pass dependent on the
467	/// HIR of every item in the local crate. Instead, use
468	/// `tcx.inferred_outlives_of()` to get the outlives for a particular
469	/// item.
470	#[derive(HashStable, Debug)]
471	pub struct CratePredicatesMap<'tcx> {
472	/// For each struct with outlive bounds, maps to a vector of the
473	/// predicate of its outlive bounds. If an item has no outlives
474	/// bounds, it will have no entry.
475	pub predicates: DefIdMap<&'tcx [(Clause<'tcx>, Span)]>,
476	}
477
478	#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
479	pub struct Term<'tcx> {
480	ptr: NonNull<()>,
481	marker: PhantomData<(Ty<'tcx>, Const<'tcx>)>,
482	}
483
484	impl<'tcx> rustc_type_ir::inherent::Term<TyCtxt<'tcx>> for Term<'tcx> {}
485
486	impl<'tcx> rustc_type_ir::inherent::IntoKind for Term<'tcx> {
487	type Kind = TermKind<'tcx>;
488
489	fn kind(self) -> Self::Kind {
490	self.unpack()
491	}
492	}
493
494	unsafe impl<'tcx> rustc_data_structures::sync::DynSend for Term<'tcx> where
495	&'tcx (Ty<'tcx>, Const<'tcx>): rustc_data_structures::sync::DynSend
496	{
497	}
498	unsafe impl<'tcx> rustc_data_structures::sync::DynSync for Term<'tcx> where
499	&'tcx (Ty<'tcx>, Const<'tcx>): rustc_data_structures::sync::DynSync
500	{
501	}
502	unsafe impl<'tcx> Send for Term<'tcx> where &'tcx (Ty<'tcx>, Const<'tcx>): Send {}
503	unsafe impl<'tcx> Sync for Term<'tcx> where &'tcx (Ty<'tcx>, Const<'tcx>): Sync {}
504
505	impl Debug for Term<'_> {
506	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
507	match self.unpack() {
508	TermKind::Ty(ty: Ty<'_>) => write!(f, "Term::Ty({ty:?})"),
509	TermKind::Const(ct: Const<'_>) => write!(f, "Term::Const({ct:?})"),
510	}
511	}
512	}
513
514	impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
515	fn from(ty: Ty<'tcx>) -> Self {
516	TermKind::Ty(ty).pack()
517	}
518	}
519
520	impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
521	fn from(c: Const<'tcx>) -> Self {
522	TermKind::Const(c).pack()
523	}
524	}
525
526	impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Term<'tcx> {
527	fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
528	self.unpack().hash_stable(hcx, hasher);
529	}
530	}
531
532	impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Term<'tcx> {
533	fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
534	self,
535	folder: &mut F,
536	) -> Result<Self, F::Error> {
537	match self.unpack() {
538	ty::TermKind::Ty(ty: Ty<'_>) => ty.try_fold_with(folder).map(op:Into::into),
539	ty::TermKind::Const(ct: Const<'_>) => ct.try_fold_with(folder).map(op:Into::into),
540	}
541	}
542	}
543
544	impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Term<'tcx> {
545	fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
546	match self.unpack() {
547	ty::TermKind::Ty(ty: Ty<'_>) => ty.visit_with(visitor),
548	ty::TermKind::Const(ct: Const<'_>) => ct.visit_with(visitor),
549	}
550	}
551	}
552
553	impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Term<'tcx> {
554	fn encode(&self, e: &mut E) {
555	self.unpack().encode(e)
556	}
557	}
558
559	impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Term<'tcx> {
560	fn decode(d: &mut D) -> Self {
561	let res: TermKind<'tcx> = Decodable::decode(d);
562	res.pack()
563	}
564	}
565
566	impl<'tcx> Term<'tcx> {
567	#[inline]
568	pub fn unpack(self) -> TermKind<'tcx> {
569	let ptr =
570	unsafe { self.ptr.map_addr(\|addr\| NonZero::new_unchecked(addr.get() & !TAG_MASK)) };
571	// SAFETY: use of `Interned::new_unchecked` here is ok because these
572	// pointers were originally created from `Interned` types in `pack()`,
573	// and this is just going in the other direction.
574	unsafe {
575	match self.ptr.addr().get() & TAG_MASK {
576	TYPE_TAG => TermKind::Ty(Ty(Interned::new_unchecked(
577	ptr.cast::<WithCachedTypeInfo<ty::TyKind<'tcx>>>().as_ref(),
578	))),
579	CONST_TAG => TermKind::Const(ty::Const(Interned::new_unchecked(
580	ptr.cast::<WithCachedTypeInfo<ty::ConstKind<'tcx>>>().as_ref(),
581	))),
582	_ => core::intrinsics::unreachable(),
583	}
584	}
585	}
586
587	pub fn as_type(&self) -> Option<Ty<'tcx>> {
588	if let TermKind::Ty(ty) = self.unpack() { Some(ty) } else { None }
589	}
590
591	pub fn expect_type(&self) -> Ty<'tcx> {
592	self.as_type().expect("expected a type, but found a const")
593	}
594
595	pub fn as_const(&self) -> Option<Const<'tcx>> {
596	if let TermKind::Const(c) = self.unpack() { Some(c) } else { None }
597	}
598
599	pub fn expect_const(&self) -> Const<'tcx> {
600	self.as_const().expect("expected a const, but found a type")
601	}
602
603	pub fn into_arg(self) -> GenericArg<'tcx> {
604	match self.unpack() {
605	TermKind::Ty(ty) => ty.into(),
606	TermKind::Const(c) => c.into(),
607	}
608	}
609
610	pub fn to_alias_term(self) -> Option<AliasTerm<'tcx>> {
611	match self.unpack() {
612	TermKind::Ty(ty) => match *ty.kind() {
613	ty::Alias(_kind, alias_ty) => Some(alias_ty.into()),
614	_ => None,
615	},
616	TermKind::Const(ct) => match ct.kind() {
617	ConstKind::Unevaluated(uv) => Some(uv.into()),
618	_ => None,
619	},
620	}
621	}
622
623	pub fn is_infer(&self) -> bool {
624	match self.unpack() {
625	TermKind::Ty(ty) => ty.is_ty_var(),
626	TermKind::Const(ct) => ct.is_ct_infer(),
627	}
628	}
629	}
630
631	const TAG_MASK: usize = `0b11`;
632	const TYPE_TAG: usize = `0b00`;
633	const CONST_TAG: usize = `0b01`;
634
635	#[extension(pub trait TermKindPackExt<'tcx>)]
636	impl<'tcx> TermKind<'tcx> {
637	#[inline]
638	fn pack(self) -> Term<'tcx> {
639	let (tag: usize, ptr: NonNull<()>) = match self {
640	TermKind::Ty(ty: Ty<'_>) => {
641	// Ensure we can use the tag bits.
642	assert_eq!(align_of_val(&*ty.0.0) & TAG_MASK, `0`);
643	(TYPE_TAG, NonNull::from(ty.0.0).cast())
644	}
645	TermKind::Const(ct: Const<'_>) => {
646	// Ensure we can use the tag bits.
647	assert_eq!(align_of_val(&*ct.0.0) & TAG_MASK, `0`);
648	(CONST_TAG, NonNull::from(ct.0.0).cast())
649	}
650	};
651
652	Term { ptr: ptr.map_addr(\|addr: NonZero\| addr \| tag), marker: PhantomData }
653	}
654	}
655
656	#[derive(Copy, Clone, PartialEq, Eq, Debug)]
657	pub enum ParamTerm {
658	Ty(ParamTy),
659	Const(ParamConst),
660	}
661
662	impl ParamTerm {
663	pub fn index(self) -> usize {
664	match self {
665	ParamTerm::Ty(ty: ParamTy) => ty.index as usize,
666	ParamTerm::Const(ct: ParamConst) => ct.index as usize,
667	}
668	}
669	}
670
671	#[derive(Copy, Clone, Eq, PartialEq, Debug)]
672	pub enum TermVid {
673	Ty(ty::TyVid),
674	Const(ty::ConstVid),
675	}
676
677	impl From<ty::TyVid> for TermVid {
678	fn from(value: ty::TyVid) -> Self {
679	TermVid::Ty(value)
680	}
681	}
682
683	impl From<ty::ConstVid> for TermVid {
684	fn from(value: ty::ConstVid) -> Self {
685	TermVid::Const(value)
686	}
687	}
688
689	/// Represents the bounds declared on a particular set of type
690	/// parameters. Should eventually be generalized into a flag list of
691	/// where-clauses. You can obtain an `InstantiatedPredicates` list from a
692	/// `GenericPredicates` by using the `instantiate` method. Note that this method
693	/// reflects an important semantic invariant of `InstantiatedPredicates`: while
694	/// the `GenericPredicates` are expressed in terms of the bound type
695	/// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
696	/// represented a set of bounds for some particular instantiation,
697	/// meaning that the generic parameters have been instantiated with
698	/// their values.
699	///
700	/// Example:
701	/// ```ignore (illustrative)
702	/// struct Foo<T, U: Bar<T>> { ... }
703	/// ```
704	/// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
705	/// `[[], [U:Bar<T>]]`. Now if there were some particular reference
706	/// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
707	/// [usize:Bar<isize>]]`.
708	#[derive(Clone, Debug, TypeFoldable, TypeVisitable)]
709	pub struct InstantiatedPredicates<'tcx> {
710	pub predicates: Vec<Clause<'tcx>>,
711	pub spans: Vec<Span>,
712	}
713
714	impl<'tcx> InstantiatedPredicates<'tcx> {
715	pub fn empty() -> InstantiatedPredicates<'tcx> {
716	InstantiatedPredicates { predicates: vec![], spans: vec![] }
717	}
718
719	pub fn is_empty(&self) -> bool {
720	self.predicates.is_empty()
721	}
722
723	pub fn iter(&self) -> <&Self as IntoIterator>::IntoIter {
724	self.into_iter()
725	}
726	}
727
728	impl<'tcx> IntoIterator for InstantiatedPredicates<'tcx> {
729	type Item = (Clause<'tcx>, Span);
730
731	type IntoIter = std::iter::Zip<std::vec::IntoIter<Clause<'tcx>>, std::vec::IntoIter<Span>>;
732
733	fn into_iter(self) -> Self::IntoIter {
734	debug_assert_eq!(self.predicates.len(), self.spans.len());
735	std::iter::zip(self.predicates, self.spans)
736	}
737	}
738
739	impl<'a, 'tcx> IntoIterator for &'a InstantiatedPredicates<'tcx> {
740	type Item = (Clause<'tcx>, Span);
741
742	type IntoIter = std::iter::Zip<
743	std::iter::Copied<std::slice::Iter<'a, Clause<'tcx>>>,
744	std::iter::Copied<std::slice::Iter<'a, Span>>,
745	>;
746
747	fn into_iter(self) -> Self::IntoIter {
748	debug_assert_eq!(self.predicates.len(), self.spans.len());
749	std::iter::zip(self.predicates.iter().copied(), self.spans.iter().copied())
750	}
751	}
752
753	#[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, HashStable, TyEncodable, TyDecodable)]
754	pub struct OpaqueHiddenType<'tcx> {
755	/// The span of this particular definition of the opaque type. So
756	/// for example:
757	///
758	/// ```ignore (incomplete snippet)
759	/// type Foo = impl Baz;
760	/// fn bar() -> Foo {
761	/// // ^^^ This is the span we are looking for!
762	/// }
763	/// ```
764	///
765	/// In cases where the fn returns `(impl Trait, impl Trait)` or
766	/// other such combinations, the result is currently
767	/// over-approximated, but better than nothing.
768	pub span: Span,
769
770	/// The type variable that represents the value of the opaque type
771	/// that we require. In other words, after we compile this function,
772	/// we will be created a constraint like:
773	/// ```ignore (pseudo-rust)
774	/// Foo<'a, T> = ?C
775	/// ```
776	/// where `?C` is the value of this type variable. =) It may
777	/// naturally refer to the type and lifetime parameters in scope
778	/// in this function, though ultimately it should only reference
779	/// those that are arguments to `Foo` in the constraint above. (In
780	/// other words, `?C` should not include `'b`, even though it's a
781	/// lifetime parameter on `foo`.)
782	pub ty: Ty<'tcx>,
783	}
784
785	impl<'tcx> OpaqueHiddenType<'tcx> {
786	pub fn build_mismatch_error(
787	&self,
788	other: &Self,
789	tcx: TyCtxt<'tcx>,
790	) -> Result<Diag<'tcx>, ErrorGuaranteed> {
791	(self.ty, other.ty).error_reported()?;
792	// Found different concrete types for the opaque type.
793	let sub_diag = if self.span == other.span {
794	TypeMismatchReason::ConflictType { span: self.span }
795	} else {
796	TypeMismatchReason::PreviousUse { span: self.span }
797	};
798	Ok(tcx.dcx().create_err(OpaqueHiddenTypeMismatch {
799	self_ty: self.ty,
800	other_ty: other.ty,
801	other_span: other.span,
802	sub: sub_diag,
803	}))
804	}
805
806	#[instrument(level = "debug", skip(tcx), ret)]
807	pub fn remap_generic_params_to_declaration_params(
808	self,
809	opaque_type_key: OpaqueTypeKey<'tcx>,
810	tcx: TyCtxt<'tcx>,
811	// typeck errors have subpar spans for opaque types, so delay error reporting until borrowck.
812	ignore_errors: bool,
813	) -> Self {
814	let OpaqueTypeKey { def_id, args } = opaque_type_key;
815
816	// Use args to build up a reverse map from regions to their
817	// identity mappings. This is necessary because of `impl
818	// Trait` lifetimes are computed by replacing existing
819	// lifetimes with 'static and remapping only those used in the
820	// `impl Trait` return type, resulting in the parameters
821	// shifting.
822	let id_args = GenericArgs::identity_for_item(tcx, def_id);
823	debug!(?id_args);
824
825	// This zip may have several times the same lifetime in `args` paired with a different
826	// lifetime from `id_args`. Simply `collect`ing the iterator is the correct behaviour:
827	// it will pick the last one, which is the one we introduced in the impl-trait desugaring.
828	let map = args.iter().zip(id_args).collect();
829	debug!("map = {:#?}", map);
830
831	// Convert the type from the function into a type valid outside
832	// the function, by replacing invalid regions with 'static,
833	// after producing an error for each of them.
834	self.fold_with(&mut opaque_types::ReverseMapper::new(tcx, map, self.span, ignore_errors))
835	}
836	}
837
838	/// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
839	/// identified by both a universe, as well as a name residing within that universe. Distinct bound
840	/// regions/types/consts within the same universe simply have an unknown relationship to one
841	/// another.
842	#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
843	#[derive(HashStable, TyEncodable, TyDecodable)]
844	pub struct Placeholder<T> {
845	pub universe: UniverseIndex,
846	pub bound: T,
847	}
848	impl Placeholder<BoundVar> {
849	pub fn find_const_ty_from_env<'tcx>(self, env: ParamEnv<'tcx>) -> Ty<'tcx> {
850	let mut candidates: impl Iterator> = env.caller_bounds().iter().filter_map(\|clause: Clause<'tcx>\| {
851	// `ConstArgHasType` are never desugared to be higher ranked.
852	match clause.kind().skip_binder() {
853	ty::ClauseKind::ConstArgHasType(placeholder_ct: Const<'_>, ty: Ty<'_>) => {
854	assert!(!(placeholder_ct, ty).has_escaping_bound_vars());
855
856	match placeholder_ct.kind() {
857	ty::ConstKind::Placeholder(placeholder_ct: Placeholder<{unknown}>) if placeholder_ct == self => {
858	Some(ty)
859	}
860	_ => None,
861	}
862	}
863	_ => None,
864	}
865	});
866
867	let ty: Ty<'_> = candidates.next().unwrap();
868	assert!(candidates.next().is_none());
869	ty
870	}
871	}
872
873	pub type PlaceholderRegion = Placeholder<BoundRegion>;
874
875	impl rustc_type_ir::inherent::PlaceholderLike for PlaceholderRegion {
876	fn universe(self) -> UniverseIndex {
877	self.universe
878	}
879
880	fn var(self) -> BoundVar {
881	self.bound.var
882	}
883
884	fn with_updated_universe(self, ui: UniverseIndex) -> Self {
885	Placeholder { universe: ui, ..self }
886	}
887
888	fn new(ui: UniverseIndex, var: BoundVar) -> Self {
889	Placeholder { universe: ui, bound: BoundRegion { var, kind: BoundRegionKind::Anon } }
890	}
891	}
892
893	pub type PlaceholderType = Placeholder<BoundTy>;
894
895	impl rustc_type_ir::inherent::PlaceholderLike for PlaceholderType {
896	fn universe(self) -> UniverseIndex {
897	self.universe
898	}
899
900	fn var(self) -> BoundVar {
901	self.bound.var
902	}
903
904	fn with_updated_universe(self, ui: UniverseIndex) -> Self {
905	Placeholder { universe: ui, ..self }
906	}
907
908	fn new(ui: UniverseIndex, var: BoundVar) -> Self {
909	Placeholder { universe: ui, bound: BoundTy { var, kind: BoundTyKind::Anon } }
910	}
911	}
912
913	#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
914	#[derive(TyEncodable, TyDecodable)]
915	pub struct BoundConst<'tcx> {
916	pub var: BoundVar,
917	pub ty: Ty<'tcx>,
918	}
919
920	pub type PlaceholderConst = Placeholder<BoundVar>;
921
922	impl rustc_type_ir::inherent::PlaceholderLike for PlaceholderConst {
923	fn universe(self) -> UniverseIndex {
924	self.universe
925	}
926
927	fn var(self) -> BoundVar {
928	self.bound
929	}
930
931	fn with_updated_universe(self, ui: UniverseIndex) -> Self {
932	Placeholder { universe: ui, ..self }
933	}
934
935	fn new(ui: UniverseIndex, var: BoundVar) -> Self {
936	Placeholder { universe: ui, bound: var }
937	}
938	}
939
940	pub type Clauses<'tcx> = &'tcx ListWithCachedTypeInfo<Clause<'tcx>>;
941
942	impl<'tcx> rustc_type_ir::Flags for Clauses<'tcx> {
943	fn flags(&self) -> TypeFlags {
944	(**self).flags()
945	}
946
947	fn outer_exclusive_binder(&self) -> DebruijnIndex {
948	(**self).outer_exclusive_binder()
949	}
950	}
951
952	/// When interacting with the type system we must provide information about the
953	/// environment. `ParamEnv` is the type that represents this information. See the
954	/// [dev guide chapter][param_env_guide] for more information.
955	///
956	/// [param_env_guide]: https://rustc-dev-guide.rust-lang.org/param_env/param_env_summary.html
957	#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
958	#[derive(HashStable, TypeVisitable, TypeFoldable)]
959	pub struct ParamEnv<'tcx> {
960	/// Caller bounds are `Obligation`s that the caller must satisfy. This is
961	/// basically the set of bounds on the in-scope type parameters, translated
962	/// into `Obligation`s, and elaborated and normalized.
963	///
964	/// Use the `caller_bounds()` method to access.
965	caller_bounds: Clauses<'tcx>,
966	}
967
968	impl<'tcx> rustc_type_ir::inherent::ParamEnv<TyCtxt<'tcx>> for ParamEnv<'tcx> {
969	fn caller_bounds(self) -> impl inherent::SliceLike<Item = ty::Clause<'tcx>> {
970	self.caller_bounds()
971	}
972	}
973
974	impl<'tcx> ParamEnv<'tcx> {
975	/// Construct a trait environment suitable for contexts where there are
976	/// no where-clauses in scope. In the majority of cases it is incorrect
977	/// to use an empty environment. See the [dev guide section][param_env_guide]
978	/// for information on what a `ParamEnv` is and how to acquire one.
979	///
980	/// [param_env_guide]: https://rustc-dev-guide.rust-lang.org/param_env/param_env_summary.html
981	#[inline]
982	pub fn empty() -> Self {
983	Self::new(ListWithCachedTypeInfo::empty())
984	}
985
986	#[inline]
987	pub fn caller_bounds(self) -> Clauses<'tcx> {
988	self.caller_bounds
989	}
990
991	/// Construct a trait environment with the given set of predicates.
992	#[inline]
993	pub fn new(caller_bounds: Clauses<'tcx>) -> Self {
994	ParamEnv { caller_bounds }
995	}
996
997	/// Creates a pair of param-env and value for use in queries.
998	pub fn and<T: TypeVisitable<TyCtxt<'tcx>>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
999	ParamEnvAnd { param_env: self, value }
1000	}
1001	}
1002
1003	#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable, TypeVisitable)]
1004	#[derive(HashStable)]
1005	pub struct ParamEnvAnd<'tcx, T> {
1006	pub param_env: ParamEnv<'tcx>,
1007	pub value: T,
1008	}
1009
1010	impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1011	pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1012	(self.param_env, self.value)
1013	}
1014	}
1015
1016	/// The environment in which to do trait solving.
1017	///
1018	/// Most of the time you only need to care about the `ParamEnv`
1019	/// as the `TypingMode` is simply stored in the `InferCtxt`.
1020	///
1021	/// However, there are some places which rely on trait solving
1022	/// without using an `InferCtxt` themselves. For these to be
1023	/// able to use the trait system they have to be able to initialize
1024	/// such an `InferCtxt` with the right `typing_mode`, so they need
1025	/// to track both.
1026	#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1027	#[derive(TypeVisitable, TypeFoldable)]
1028	pub struct TypingEnv<'tcx> {
1029	pub typing_mode: TypingMode<'tcx>,
1030	pub param_env: ParamEnv<'tcx>,
1031	}
1032
1033	impl<'tcx> TypingEnv<'tcx> {
1034	/// Create a typing environment with no where-clauses in scope
1035	/// where all opaque types and default associated items are revealed.
1036	///
1037	/// This is only suitable for monomorphized, post-typeck environments.
1038	/// Do not use this for MIR optimizations, as even though they also
1039	/// use `TypingMode::PostAnalysis`, they may still have where-clauses
1040	/// in scope.
1041	pub fn fully_monomorphized() -> TypingEnv<'tcx> {
1042	TypingEnv { typing_mode: TypingMode::PostAnalysis, param_env: ParamEnv::empty() }
1043	}
1044
1045	/// Create a typing environment for use during analysis outside of a body.
1046	///
1047	/// Using a typing environment inside of bodies is not supported as the body
1048	/// may define opaque types. In this case the used functions have to be
1049	/// converted to use proper canonical inputs instead.
1050	pub fn non_body_analysis(
1051	tcx: TyCtxt<'tcx>,
1052	def_id: impl IntoQueryParam<DefId>,
1053	) -> TypingEnv<'tcx> {
1054	TypingEnv { typing_mode: TypingMode::non_body_analysis(), param_env: tcx.param_env(def_id) }
1055	}
1056
1057	pub fn post_analysis(tcx: TyCtxt<'tcx>, def_id: impl IntoQueryParam<DefId>) -> TypingEnv<'tcx> {
1058	TypingEnv {
1059	typing_mode: TypingMode::PostAnalysis,
1060	param_env: tcx.param_env_normalized_for_post_analysis(def_id),
1061	}
1062	}
1063
1064	/// Modify the `typing_mode` to `PostAnalysis` and eagerly reveal all
1065	/// opaque types in the `param_env`.
1066	pub fn with_post_analysis_normalized(self, tcx: TyCtxt<'tcx>) -> TypingEnv<'tcx> {
1067	let TypingEnv { typing_mode, param_env } = self;
1068	if let TypingMode::PostAnalysis = typing_mode {
1069	return self;
1070	}
1071
1072	// No need to reveal opaques with the new solver enabled,
1073	// since we have lazy norm.
1074	let param_env = if tcx.next_trait_solver_globally() {
1075	ParamEnv::new(param_env.caller_bounds())
1076	} else {
1077	ParamEnv::new(tcx.reveal_opaque_types_in_bounds(param_env.caller_bounds()))
1078	};
1079	TypingEnv { typing_mode: TypingMode::PostAnalysis, param_env }
1080	}
1081
1082	/// Combine this typing environment with the given `value` to be used by
1083	/// not (yet) canonicalized queries. This only works if the value does not
1084	/// contain anything local to some `InferCtxt`, i.e. inference variables or
1085	/// placeholders.
1086	pub fn as_query_input<T>(self, value: T) -> PseudoCanonicalInput<'tcx, T>
1087	where
1088	T: TypeVisitable<TyCtxt<'tcx>>,
1089	{
1090	// FIXME(#132279): We should assert that the value does not contain any placeholders
1091	// as these placeholders are also local to the current inference context. However, we
1092	// currently use pseudo-canonical queries in the trait solver which replaces params with
1093	// placeholders. We should also simply not use pseudo-canonical queries in the trait
1094	// solver, at which point we can readd this assert. As of writing this comment, this is
1095	// only used by `fn layout_is_pointer_like` when calling `layout_of`.
1096	//
1097	// debug_assert!(!value.has_placeholders());
1098	PseudoCanonicalInput { typing_env: self, value }
1099	}
1100	}
1101
1102	/// Similar to `CanonicalInput`, this carries the `typing_mode` and the environment
1103	/// necessary to do any kind of trait solving inside of nested queries.
1104	///
1105	/// Unlike proper canonicalization, this requires the `param_env` and the `value` to not
1106	/// contain anything local to the `infcx` of the caller, so we don't actually canonicalize
1107	/// anything.
1108	///
1109	/// This should be created by using `infcx.pseudo_canonicalize_query(param_env, value)`
1110	/// or by using `typing_env.as_query_input(value)`.
1111	#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1112	#[derive(HashStable, TypeVisitable, TypeFoldable)]
1113	pub struct PseudoCanonicalInput<'tcx, T> {
1114	pub typing_env: TypingEnv<'tcx>,
1115	pub value: T,
1116	}
1117
1118	#[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
1119	pub struct Destructor {
1120	/// The `DefId` of the destructor method
1121	pub did: DefId,
1122	/// The constness of the destructor method
1123	pub constness: hir::Constness,
1124	}
1125
1126	// FIXME: consider combining this definition with regular `Destructor`
1127	#[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
1128	pub struct AsyncDestructor {
1129	/// The `DefId` of the async destructor future constructor
1130	pub ctor: DefId,
1131	/// The `DefId` of the async destructor future type
1132	pub future: DefId,
1133	}
1134
1135	#[derive(Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
1136	pub struct VariantFlags(u8);
1137	bitflags::bitflags! {
1138	impl VariantFlags: u8 {
1139	const NO_VARIANT_FLAGS = `0`;
1140	/// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1141	const IS_FIELD_LIST_NON_EXHAUSTIVE = `1` << `0`;
1142	}
1143	}
1144	rustc_data_structures::external_bitflags_debug! { VariantFlags }
1145
1146	/// Definition of a variant -- a struct's fields or an enum variant.
1147	#[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1148	pub struct VariantDef {
1149	/// `DefId` that identifies the variant itself.
1150	/// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1151	pub def_id: DefId,
1152	/// `DefId` that identifies the variant's constructor.
1153	/// If this variant is a struct variant, then this is `None`.
1154	pub ctor: Option<(CtorKind, DefId)>,
1155	/// Variant or struct name.
1156	pub name: Symbol,
1157	/// Discriminant of this variant.
1158	pub discr: VariantDiscr,
1159	/// Fields of this variant.
1160	pub fields: IndexVec<FieldIdx, FieldDef>,
1161	/// The error guarantees from parser, if any.
1162	tainted: Option<ErrorGuaranteed>,
1163	/// Flags of the variant (e.g. is field list non-exhaustive)?
1164	flags: VariantFlags,
1165	}
1166
1167	impl VariantDef {
1168	/// Creates a new `VariantDef`.
1169	///
1170	/// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1171	/// represents an enum variant).
1172	///
1173	/// `ctor_did` is the `DefId` that identifies the constructor of unit or
1174	/// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1175	///
1176	/// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1177	/// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1178	/// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1179	/// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1180	/// built-in trait), and we do not want to load attributes twice.
1181	///
1182	/// If someone speeds up attribute loading to not be a performance concern, they can
1183	/// remove this hack and use the constructor `DefId` everywhere.
1184	#[instrument(level = "debug")]
1185	pub fn new(
1186	name: Symbol,
1187	variant_did: Option<DefId>,
1188	ctor: Option<(CtorKind, DefId)>,
1189	discr: VariantDiscr,
1190	fields: IndexVec<FieldIdx, FieldDef>,
1191	parent_did: DefId,
1192	recover_tainted: Option<ErrorGuaranteed>,
1193	is_field_list_non_exhaustive: bool,
1194	) -> Self {
1195	let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1196	if is_field_list_non_exhaustive {
1197	flags \|= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1198	}
1199
1200	VariantDef {
1201	def_id: variant_did.unwrap_or(parent_did),
1202	ctor,
1203	name,
1204	discr,
1205	fields,
1206	flags,
1207	tainted: recover_tainted,
1208	}
1209	}
1210
1211	/// Returns `true` if the field list of this variant is `#[non_exhaustive]`.
1212	///
1213	/// Note that this function will return `true` even if the type has been
1214	/// defined in the crate currently being compiled. If that's not what you
1215	/// want, see [`Self::field_list_has_applicable_non_exhaustive`].
1216	#[inline]
1217	pub fn is_field_list_non_exhaustive(&self) -> bool {
1218	self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1219	}
1220
1221	/// Returns `true` if the field list of this variant is `#[non_exhaustive]`
1222	/// and the type has been defined in another crate.
1223	#[inline]
1224	pub fn field_list_has_applicable_non_exhaustive(&self) -> bool {
1225	self.is_field_list_non_exhaustive() && !self.def_id.is_local()
1226	}
1227
1228	/// Computes the `Ident` of this variant by looking up the `Span`
1229	pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1230	Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1231	}
1232
1233	/// Was this variant obtained as part of recovering from a syntactic error?
1234	#[inline]
1235	pub fn has_errors(&self) -> Result<(), ErrorGuaranteed> {
1236	self.tainted.map_or(Ok(()), Err)
1237	}
1238
1239	#[inline]
1240	pub fn ctor_kind(&self) -> Option<CtorKind> {
1241	self.ctor.map(\|(kind, _)\| kind)
1242	}
1243
1244	#[inline]
1245	pub fn ctor_def_id(&self) -> Option<DefId> {
1246	self.ctor.map(\|(_, def_id)\| def_id)
1247	}
1248
1249	/// Returns the one field in this variant.
1250	///
1251	/// `panic!`s if there are no fields or multiple fields.
1252	#[inline]
1253	pub fn single_field(&self) -> &FieldDef {
1254	assert!(self.fields.len() == `1`);
1255
1256	&self.fields[FieldIdx::ZERO]
1257	}
1258
1259	/// Returns the last field in this variant, if present.
1260	#[inline]
1261	pub fn tail_opt(&self) -> Option<&FieldDef> {
1262	self.fields.raw.last()
1263	}
1264
1265	/// Returns the last field in this variant.
1266	///
1267	/// # Panics
1268	///
1269	/// Panics, if the variant has no fields.
1270	#[inline]
1271	pub fn tail(&self) -> &FieldDef {
1272	self.tail_opt().expect("expected unsized ADT to have a tail field")
1273	}
1274
1275	/// Returns whether this variant has unsafe fields.
1276	pub fn has_unsafe_fields(&self) -> bool {
1277	self.fields.iter().any(\|x\| x.safety.is_unsafe())
1278	}
1279	}
1280
1281	impl PartialEq for VariantDef {
1282	#[inline]
1283	fn eq(&self, other: &Self) -> bool {
1284	// There should be only one `VariantDef` for each `def_id`, therefore
1285	// it is fine to implement `PartialEq` only based on `def_id`.
1286	//
1287	// Below, we exhaustively destructure `self` and `other` so that if the
1288	// definition of `VariantDef` changes, a compile-error will be produced,
1289	// reminding us to revisit this assumption.
1290
1291	let Self {
1292	def_id: lhs_def_id,
1293	ctor: _,
1294	name: _,
1295	discr: _,
1296	fields: _,
1297	flags: _,
1298	tainted: _,
1299	} = &self;
1300	let Self {
1301	def_id: rhs_def_id,
1302	ctor: _,
1303	name: _,
1304	discr: _,
1305	fields: _,
1306	flags: _,
1307	tainted: _,
1308	} = other;
1309
1310	let res = lhs_def_id == rhs_def_id;
1311
1312	// Double check that implicit assumption detailed above.
1313	if cfg!(debug_assertions) && res {
1314	let deep = self.ctor == other.ctor
1315	&& self.name == other.name
1316	&& self.discr == other.discr
1317	&& self.fields == other.fields
1318	&& self.flags == other.flags;
1319	assert!(deep, "VariantDef for the same def-id has differing data");
1320	}
1321
1322	res
1323	}
1324	}
1325
1326	impl Eq for VariantDef {}
1327
1328	impl Hash for VariantDef {
1329	#[inline]
1330	fn hash<H: Hasher>(&self, s: &mut H) {
1331	// There should be only one `VariantDef` for each `def_id`, therefore
1332	// it is fine to implement `Hash` only based on `def_id`.
1333	//
1334	// Below, we exhaustively destructure `self` so that if the definition
1335	// of `VariantDef` changes, a compile-error will be produced, reminding
1336	// us to revisit this assumption.
1337
1338	let Self { def_id: &DefId, ctor: _, name: _, discr: _, fields: _, flags: _, tainted: _ } = &self;
1339	def_id.hash(state:s)
1340	}
1341	}
1342
1343	#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1344	pub enum VariantDiscr {
1345	/// Explicit value for this variant, i.e., `X = 123`.
1346	/// The `DefId` corresponds to the embedded constant.
1347	Explicit(DefId),
1348
1349	/// The previous variant's discriminant plus one.
1350	/// For efficiency reasons, the distance from the
1351	/// last `Explicit` discriminant is being stored,
1352	/// or `0` for the first variant, if it has none.
1353	Relative(u32),
1354	}
1355
1356	#[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1357	pub struct FieldDef {
1358	pub did: DefId,
1359	pub name: Symbol,
1360	pub vis: Visibility<DefId>,
1361	pub safety: hir::Safety,
1362	pub value: Option<DefId>,
1363	}
1364
1365	impl PartialEq for FieldDef {
1366	#[inline]
1367	fn eq(&self, other: &Self) -> bool {
1368	// There should be only one `FieldDef` for each `did`, therefore it is
1369	// fine to implement `PartialEq` only based on `did`.
1370	//
1371	// Below, we exhaustively destructure `self` so that if the definition
1372	// of `FieldDef` changes, a compile-error will be produced, reminding
1373	// us to revisit this assumption.
1374
1375	let Self { did: lhs_did, name: _, vis: _, safety: _, value: _ } = &self;
1376
1377	let Self { did: rhs_did, name: _, vis: _, safety: _, value: _ } = other;
1378
1379	let res = lhs_did == rhs_did;
1380
1381	// Double check that implicit assumption detailed above.
1382	if cfg!(debug_assertions) && res {
1383	let deep =
1384	self.name == other.name && self.vis == other.vis && self.safety == other.safety;
1385	assert!(deep, "FieldDef for the same def-id has differing data");
1386	}
1387
1388	res
1389	}
1390	}
1391
1392	impl Eq for FieldDef {}
1393
1394	impl Hash for FieldDef {
1395	#[inline]
1396	fn hash<H: Hasher>(&self, s: &mut H) {
1397	// There should be only one `FieldDef` for each `did`, therefore it is
1398	// fine to implement `Hash` only based on `did`.
1399	//
1400	// Below, we exhaustively destructure `self` so that if the definition
1401	// of `FieldDef` changes, a compile-error will be produced, reminding
1402	// us to revisit this assumption.
1403
1404	let Self { did: &DefId, name: _, vis: _, safety: _, value: _ } = &self;
1405
1406	did.hash(state:s)
1407	}
1408	}
1409
1410	impl<'tcx> FieldDef {
1411	/// Returns the type of this field. The resulting type is not normalized. The `arg` is
1412	/// typically obtained via the second field of [`TyKind::Adt`].
1413	pub fn ty(&self, tcx: TyCtxt<'tcx>, args: GenericArgsRef<'tcx>) -> Ty<'tcx> {
1414	tcx.type_of(self.did).instantiate(cx:tcx, args)
1415	}
1416
1417	/// Computes the `Ident` of this variant by looking up the `Span`
1418	pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1419	Ident::new(self.name, span:tcx.def_ident_span(self.did).unwrap())
1420	}
1421	}
1422
1423	#[derive(Debug, PartialEq, Eq)]
1424	pub enum ImplOverlapKind {
1425	/// These impls are always allowed to overlap.
1426	Permitted {
1427	/// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1428	marker: bool,
1429	},
1430	}
1431
1432	/// Useful source information about where a desugared associated type for an
1433	/// RPITIT originated from.
1434	#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Encodable, Decodable, HashStable)]
1435	pub enum ImplTraitInTraitData {
1436	Trait { fn_def_id: DefId, opaque_def_id: DefId },
1437	Impl { fn_def_id: DefId },
1438	}
1439
1440	impl<'tcx> TyCtxt<'tcx> {
1441	pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1442	self.typeck(self.hir_body_owner_def_id(body))
1443	}
1444
1445	pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1446	self.associated_items(id)
1447	.in_definition_order()
1448	.filter(move \|item\| item.kind == AssocKind::Fn && item.defaultness(self).has_value())
1449	}
1450
1451	pub fn repr_options_of_def(self, did: LocalDefId) -> ReprOptions {
1452	let mut flags = ReprFlags::empty();
1453	let mut size = None;
1454	let mut max_align: Option<Align> = None;
1455	let mut min_pack: Option<Align> = None;
1456
1457	// Generate a deterministically-derived seed from the item's path hash
1458	// to allow for cross-crate compilation to actually work
1459	let mut field_shuffle_seed = self.def_path_hash(did.to_def_id()).0.to_smaller_hash();
1460
1461	// If the user defined a custom seed for layout randomization, xor the item's
1462	// path hash with the user defined seed, this will allowing determinism while
1463	// still allowing users to further randomize layout generation for e.g. fuzzing
1464	if let Some(user_seed) = self.sess.opts.unstable_opts.layout_seed {
1465	field_shuffle_seed ^= user_seed;
1466	}
1467
1468	if let Some(reprs) = attr::find_attr!(self.get_all_attrs(did), AttributeKind::Repr(r) => r)
1469	{
1470	for (r, _) in reprs {
1471	flags.insert(match *r {
1472	attr::ReprRust => ReprFlags::empty(),
1473	attr::ReprC => ReprFlags::IS_C,
1474	attr::ReprPacked(pack) => {
1475	min_pack = Some(if let Some(min_pack) = min_pack {
1476	min_pack.min(pack)
1477	} else {
1478	pack
1479	});
1480	ReprFlags::empty()
1481	}
1482	attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1483	attr::ReprSimd => ReprFlags::IS_SIMD,
1484	attr::ReprInt(i) => {
1485	size = Some(match i {
1486	attr::IntType::SignedInt(x) => match x {
1487	ast::IntTy::Isize => IntegerType::Pointer(`true`),
1488	ast::IntTy::I8 => IntegerType::Fixed(Integer::I8, `true`),
1489	ast::IntTy::I16 => IntegerType::Fixed(Integer::I16, `true`),
1490	ast::IntTy::I32 => IntegerType::Fixed(Integer::I32, `true`),
1491	ast::IntTy::I64 => IntegerType::Fixed(Integer::I64, `true`),
1492	ast::IntTy::I128 => IntegerType::Fixed(Integer::I128, `true`),
1493	},
1494	attr::IntType::UnsignedInt(x) => match x {
1495	ast::UintTy::Usize => IntegerType::Pointer(`false`),
1496	ast::UintTy::U8 => IntegerType::Fixed(Integer::I8, `false`),
1497	ast::UintTy::U16 => IntegerType::Fixed(Integer::I16, `false`),
1498	ast::UintTy::U32 => IntegerType::Fixed(Integer::I32, `false`),
1499	ast::UintTy::U64 => IntegerType::Fixed(Integer::I64, `false`),
1500	ast::UintTy::U128 => IntegerType::Fixed(Integer::I128, `false`),
1501	},
1502	});
1503	ReprFlags::empty()
1504	}
1505	attr::ReprAlign(align) => {
1506	max_align = max_align.max(Some(align));
1507	ReprFlags::empty()
1508	}
1509	attr::ReprEmpty => {
1510	/ skip these, they're just for diagnostics /
1511	ReprFlags::empty()
1512	}
1513	});
1514	}
1515	}
1516
1517	// If `-Z randomize-layout` was enabled for the type definition then we can
1518	// consider performing layout randomization
1519	if self.sess.opts.unstable_opts.randomize_layout {
1520	flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1521	}
1522
1523	// box is special, on the one hand the compiler assumes an ordered layout, with the pointer
1524	// always at offset zero. On the other hand we want scalar abi optimizations.
1525	let is_box = self.is_lang_item(did.to_def_id(), LangItem::OwnedBox);
1526
1527	// This is here instead of layout because the choice must make it into metadata.
1528	if is_box {
1529	flags.insert(ReprFlags::IS_LINEAR);
1530	}
1531
1532	ReprOptions { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1533	}
1534
1535	/// Look up the name of a definition across crates. This does not look at HIR.
1536	pub fn opt_item_name(self, def_id: DefId) -> Option<Symbol> {
1537	if let Some(cnum) = def_id.as_crate_root() {
1538	Some(self.crate_name(cnum))
1539	} else {
1540	let def_key = self.def_key(def_id);
1541	match def_key.disambiguated_data.data {
1542	// The name of a constructor is that of its parent.
1543	rustc_hir::definitions::DefPathData::Ctor => self
1544	.opt_item_name(DefId { krate: def_id.krate, index: def_key.parent.unwrap() }),
1545	_ => def_key.get_opt_name(),
1546	}
1547	}
1548	}
1549
1550	/// Look up the name of a definition across crates. This does not look at HIR.
1551	///
1552	/// This method will ICE if the corresponding item does not have a name. In these cases, use
1553	/// [`opt_item_name`] instead.
1554	///
1555	/// [`opt_item_name`]: Self::opt_item_name
1556	pub fn item_name(self, id: DefId) -> Symbol {
1557	self.opt_item_name(id).unwrap_or_else(\|\| {
1558	bug!("item_name: no name for {:?}", self.def_path(id));
1559	})
1560	}
1561
1562	/// Look up the name and span of a definition.
1563	///
1564	/// See [`item_name`][Self::item_name] for more information.
1565	pub fn opt_item_ident(self, def_id: DefId) -> Option<Ident> {
1566	let def = self.opt_item_name(def_id)?;
1567	let span = self
1568	.def_ident_span(def_id)
1569	.unwrap_or_else(\|\| bug!("missing ident span for {def_id:?}"));
1570	Some(Ident::new(def, span))
1571	}
1572
1573	/// Look up the name and span of a definition.
1574	///
1575	/// See [`item_name`][Self::item_name] for more information.
1576	pub fn item_ident(self, def_id: DefId) -> Ident {
1577	self.opt_item_ident(def_id).unwrap_or_else(\|\| {
1578	bug!("item_ident: no name for {:?}", self.def_path(def_id));
1579	})
1580	}
1581
1582	pub fn opt_associated_item(self, def_id: DefId) -> Option<AssocItem> {
1583	if let DefKind::AssocConst \| DefKind::AssocFn \| DefKind::AssocTy = self.def_kind(def_id) {
1584	Some(self.associated_item(def_id))
1585	} else {
1586	None
1587	}
1588	}
1589
1590	/// If the `def_id` is an associated type that was desugared from a
1591	/// return-position `impl Trait` from a trait, then provide the source info
1592	/// about where that RPITIT came from.
1593	pub fn opt_rpitit_info(self, def_id: DefId) -> Option<ImplTraitInTraitData> {
1594	if let DefKind::AssocTy = self.def_kind(def_id) {
1595	self.associated_item(def_id).opt_rpitit_info
1596	} else {
1597	None
1598	}
1599	}
1600
1601	pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<FieldIdx> {
1602	variant.fields.iter_enumerated().find_map(\|(i, field)\| {
1603	self.hygienic_eq(ident, field.ident(self), variant.def_id).then_some(i)
1604	})
1605	}
1606
1607	/// Returns `Some` if the impls are the same polarity and the trait either
1608	/// has no items or is annotated `#[marker]` and prevents item overrides.
1609	#[instrument(level = "debug", skip(self), ret)]
1610	pub fn impls_are_allowed_to_overlap(
1611	self,
1612	def_id1: DefId,
1613	def_id2: DefId,
1614	) -> Option<ImplOverlapKind> {
1615	let impl1 = self.impl_trait_header(def_id1).unwrap();
1616	let impl2 = self.impl_trait_header(def_id2).unwrap();
1617
1618	let trait_ref1 = impl1.trait_ref.skip_binder();
1619	let trait_ref2 = impl2.trait_ref.skip_binder();
1620
1621	// If either trait impl references an error, they're allowed to overlap,
1622	// as one of them essentially doesn't exist.
1623	if trait_ref1.references_error() \|\| trait_ref2.references_error() {
1624	return Some(ImplOverlapKind::Permitted { marker: `false` });
1625	}
1626
1627	match (impl1.polarity, impl2.polarity) {
1628	(ImplPolarity::Reservation, _) \| (_, ImplPolarity::Reservation) => {
1629	// `#[rustc_reservation_impl]` impls don't overlap with anything
1630	return Some(ImplOverlapKind::Permitted { marker: `false` });
1631	}
1632	(ImplPolarity::Positive, ImplPolarity::Negative)
1633	\| (ImplPolarity::Negative, ImplPolarity::Positive) => {
1634	// `impl AutoTrait for Type` + `impl !AutoTrait for Type`
1635	return None;
1636	}
1637	(ImplPolarity::Positive, ImplPolarity::Positive)
1638	\| (ImplPolarity::Negative, ImplPolarity::Negative) => {}
1639	};
1640
1641	let is_marker_impl = \|trait_ref: TraitRef<'_>\| self.trait_def(trait_ref.def_id).is_marker;
1642	let is_marker_overlap = is_marker_impl(trait_ref1) && is_marker_impl(trait_ref2);
1643
1644	if is_marker_overlap {
1645	return Some(ImplOverlapKind::Permitted { marker: `true` });
1646	}
1647
1648	None
1649	}
1650
1651	/// Returns `ty::VariantDef` if `res` refers to a struct,
1652	/// or variant or their constructors, panics otherwise.
1653	pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
1654	match res {
1655	Res::Def(DefKind::Variant, did) => {
1656	let enum_did = self.parent(did);
1657	self.adt_def(enum_did).variant_with_id(did)
1658	}
1659	Res::Def(DefKind::Struct \| DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
1660	Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
1661	let variant_did = self.parent(variant_ctor_did);
1662	let enum_did = self.parent(variant_did);
1663	self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
1664	}
1665	Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
1666	let struct_did = self.parent(ctor_did);
1667	self.adt_def(struct_did).non_enum_variant()
1668	}
1669	_ => bug!("expect_variant_res used with unexpected res {:?}", res),
1670	}
1671	}
1672
1673	/// Returns the possibly-auto-generated MIR of a [`ty::InstanceKind`].
1674	#[instrument(skip(self), level = "debug")]
1675	pub fn instance_mir(self, instance: ty::InstanceKind<'tcx>) -> &'tcx Body<'tcx> {
1676	match instance {
1677	ty::InstanceKind::Item(def) => {
1678	debug!("calling def_kind on def: {:?}", def);
1679	let def_kind = self.def_kind(def);
1680	debug!("returned from def_kind: {:?}", def_kind);
1681	match def_kind {
1682	DefKind::Const
1683	\| DefKind::Static { .. }
1684	\| DefKind::AssocConst
1685	\| DefKind::Ctor(..)
1686	\| DefKind::AnonConst
1687	\| DefKind::InlineConst => self.mir_for_ctfe(def),
1688	// If the caller wants `mir_for_ctfe` of a function they should not be using
1689	// `instance_mir`, so we'll assume const fn also wants the optimized version.
1690	_ => self.optimized_mir(def),
1691	}
1692	}
1693	ty::InstanceKind::VTableShim(..)
1694	\| ty::InstanceKind::ReifyShim(..)
1695	\| ty::InstanceKind::Intrinsic(..)
1696	\| ty::InstanceKind::FnPtrShim(..)
1697	\| ty::InstanceKind::Virtual(..)
1698	\| ty::InstanceKind::ClosureOnceShim { .. }
1699	\| ty::InstanceKind::ConstructCoroutineInClosureShim { .. }
1700	\| ty::InstanceKind::DropGlue(..)
1701	\| ty::InstanceKind::CloneShim(..)
1702	\| ty::InstanceKind::ThreadLocalShim(..)
1703	\| ty::InstanceKind::FnPtrAddrShim(..)
1704	\| ty::InstanceKind::AsyncDropGlueCtorShim(..) => self.mir_shims(instance),
1705	}
1706	}
1707
1708	// FIXME(@lcnr): Remove this function.
1709	pub fn get_attrs_unchecked(self, did: DefId) -> &'tcx [hir::Attribute] {
1710	if let Some(did) = did.as_local() {
1711	self.hir_attrs(self.local_def_id_to_hir_id(did))
1712	} else {
1713	self.attrs_for_def(did)
1714	}
1715	}
1716
1717	/// Gets all attributes with the given name.
1718	pub fn get_attrs(
1719	self,
1720	did: impl Into<DefId>,
1721	attr: Symbol,
1722	) -> impl Iterator<Item = &'tcx hir::Attribute> {
1723	self.get_all_attrs(did).filter(move \|a: &&hir::Attribute\| a.has_name(attr))
1724	}
1725
1726	/// Gets all attributes.
1727	///
1728	/// To see if an item has a specific attribute, you should use [`rustc_attr_data_structures::find_attr!`] so you can use matching.
1729	pub fn get_all_attrs(
1730	self,
1731	did: impl Into<DefId>,
1732	) -> impl Iterator<Item = &'tcx hir::Attribute> {
1733	let did: DefId = did.into();
1734	if let Some(did) = did.as_local() {
1735	self.hir_attrs(self.local_def_id_to_hir_id(did)).iter()
1736	} else {
1737	self.attrs_for_def(did).iter()
1738	}
1739	}
1740
1741	/// Get an attribute from the diagnostic attribute namespace
1742	///
1743	/// This function requests an attribute with the following structure:
1744	///
1745	/// `#[diagnostic::$attr]`
1746	///
1747	/// This function performs feature checking, so if an attribute is returned
1748	/// it can be used by the consumer
1749	pub fn get_diagnostic_attr(
1750	self,
1751	did: impl Into<DefId>,
1752	attr: Symbol,
1753	) -> Option<&'tcx hir::Attribute> {
1754	let did: DefId = did.into();
1755	if did.as_local().is_some() {
1756	// it's a crate local item, we need to check feature flags
1757	if rustc_feature::is_stable_diagnostic_attribute(attr, self.features()) {
1758	self.get_attrs_by_path(did, &[sym::diagnostic, sym::do_not_recommend]).next()
1759	} else {
1760	None
1761	}
1762	} else {
1763	// we filter out unstable diagnostic attributes before
1764	// encoding attributes
1765	debug_assert!(rustc_feature::encode_cross_crate(attr));
1766	self.attrs_for_def(did)
1767	.iter()
1768	.find(\|a\| matches!(a.path().as_ref(), [sym::diagnostic, a] if *a == attr))
1769	}
1770	}
1771
1772	pub fn get_attrs_by_path(
1773	self,
1774	did: DefId,
1775	attr: &[Symbol],
1776	) -> impl Iterator<Item = &'tcx hir::Attribute> {
1777	let filter_fn = move \|a: &&hir::Attribute\| a.path_matches(attr);
1778	if let Some(did) = did.as_local() {
1779	self.hir_attrs(self.local_def_id_to_hir_id(did)).iter().filter(filter_fn)
1780	} else {
1781	self.attrs_for_def(did).iter().filter(filter_fn)
1782	}
1783	}
1784
1785	pub fn get_attr(self, did: impl Into<DefId>, attr: Symbol) -> Option<&'tcx hir::Attribute> {
1786	if cfg!(debug_assertions) && !rustc_feature::is_valid_for_get_attr(attr) {
1787	let did: DefId = did.into();
1788	bug!("get_attr: unexpected called with DefId `{:?}`, attr `{:?}`", did, attr);
1789	} else {
1790	self.get_attrs(did, attr).next()
1791	}
1792	}
1793
1794	/// Determines whether an item is annotated with an attribute.
1795	pub fn has_attr(self, did: impl Into<DefId>, attr: Symbol) -> bool {
1796	self.get_attrs(did, attr).next().is_some()
1797	}
1798
1799	/// Determines whether an item is annotated with a multi-segment attribute
1800	pub fn has_attrs_with_path(self, did: impl Into<DefId>, attrs: &[Symbol]) -> bool {
1801	self.get_attrs_by_path(did.into(), attrs).next().is_some()
1802	}
1803
1804	/// Returns `true` if this is an `auto trait`.
1805	pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
1806	self.trait_def(trait_def_id).has_auto_impl
1807	}
1808
1809	/// Returns `true` if this is coinductive, either because it is
1810	/// an auto trait or because it has the `#[rustc_coinductive]` attribute.
1811	pub fn trait_is_coinductive(self, trait_def_id: DefId) -> bool {
1812	self.trait_def(trait_def_id).is_coinductive
1813	}
1814
1815	/// Returns `true` if this is a trait alias.
1816	pub fn trait_is_alias(self, trait_def_id: DefId) -> bool {
1817	self.def_kind(trait_def_id) == DefKind::TraitAlias
1818	}
1819
1820	/// Returns layout of a coroutine. Layout might be unavailable if the
1821	/// coroutine is tainted by errors.
1822	///
1823	/// Takes `coroutine_kind` which can be acquired from the `CoroutineArgs::kind_ty`,
1824	/// e.g. `args.as_coroutine().kind_ty()`.
1825	pub fn coroutine_layout(
1826	self,
1827	def_id: DefId,
1828	coroutine_kind_ty: Ty<'tcx>,
1829	) -> Option<&'tcx CoroutineLayout<'tcx>> {
1830	let mir = self.optimized_mir(def_id);
1831	// Regular coroutine
1832	if coroutine_kind_ty.is_unit() {
1833	mir.coroutine_layout_raw()
1834	} else {
1835	// If we have a `Coroutine` that comes from an coroutine-closure,
1836	// then it may be a by-move or by-ref body.
1837	let ty::Coroutine(_, identity_args) =
1838	*self.type_of(def_id).instantiate_identity().kind()
1839	else {
1840	unreachable!();
1841	};
1842	let identity_kind_ty = identity_args.as_coroutine().kind_ty();
1843	// If the types differ, then we must be getting the by-move body of
1844	// a by-ref coroutine.
1845	if identity_kind_ty == coroutine_kind_ty {
1846	mir.coroutine_layout_raw()
1847	} else {
1848	assert_matches!(coroutine_kind_ty.to_opt_closure_kind(), Some(ClosureKind::FnOnce));
1849	assert_matches!(
1850	identity_kind_ty.to_opt_closure_kind(),
1851	Some(ClosureKind::Fn \| ClosureKind::FnMut)
1852	);
1853	self.optimized_mir(self.coroutine_by_move_body_def_id(def_id))
1854	.coroutine_layout_raw()
1855	}
1856	}
1857	}
1858
1859	/// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
1860	/// If it implements no trait, returns `None`.
1861	pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
1862	self.impl_trait_ref(def_id).map(\|tr\| tr.skip_binder().def_id)
1863	}
1864
1865	/// If the given `DefId` describes an item belonging to a trait,
1866	/// returns the `DefId` of the trait that the trait item belongs to;
1867	/// otherwise, returns `None`.
1868	pub fn trait_of_item(self, def_id: DefId) -> Option<DefId> {
1869	if let DefKind::AssocConst \| DefKind::AssocFn \| DefKind::AssocTy = self.def_kind(def_id) {
1870	let parent = self.parent(def_id);
1871	if let DefKind::Trait \| DefKind::TraitAlias = self.def_kind(parent) {
1872	return Some(parent);
1873	}
1874	}
1875	None
1876	}
1877
1878	/// If the given `DefId` describes a method belonging to an impl, returns the
1879	/// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
1880	pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
1881	if let DefKind::AssocConst \| DefKind::AssocFn \| DefKind::AssocTy = self.def_kind(def_id) {
1882	let parent = self.parent(def_id);
1883	if let DefKind::Impl { .. } = self.def_kind(parent) {
1884	return Some(parent);
1885	}
1886	}
1887	None
1888	}
1889
1890	/// Check if the given `DefId` is `#\[automatically_derived\]`, and
1891	/// whether it was produced by expanding a builtin derive macro.
1892	pub fn is_builtin_derived(self, def_id: DefId) -> bool {
1893	if self.is_automatically_derived(def_id)
1894	&& let Some(def_id) = def_id.as_local()
1895	&& let outer = self.def_span(def_id).ctxt().outer_expn_data()
1896	&& matches!(outer.kind, ExpnKind::Macro(MacroKind::Derive, _))
1897	&& self.has_attr(outer.macro_def_id.unwrap(), sym::rustc_builtin_macro)
1898	{
1899	`true`
1900	} else {
1901	`false`
1902	}
1903	}
1904
1905	/// Check if the given `DefId` is `#\[automatically_derived\]`.
1906	pub fn is_automatically_derived(self, def_id: DefId) -> bool {
1907	self.has_attr(def_id, sym::automatically_derived)
1908	}
1909
1910	/// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
1911	/// with the name of the crate containing the impl.
1912	pub fn span_of_impl(self, impl_def_id: DefId) -> Result<Span, Symbol> {
1913	if let Some(impl_def_id) = impl_def_id.as_local() {
1914	Ok(self.def_span(impl_def_id))
1915	} else {
1916	Err(self.crate_name(impl_def_id.krate))
1917	}
1918	}
1919
1920	/// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
1921	/// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
1922	/// definition's parent/scope to perform comparison.
1923	pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
1924	// We could use `Ident::eq` here, but we deliberately don't. The name
1925	// comparison fails frequently, and we want to avoid the expensive
1926	// `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
1927	use_name.name == def_name.name
1928	&& use_name
1929	.span
1930	.ctxt()
1931	.hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
1932	}
1933
1934	pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
1935	ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
1936	ident
1937	}
1938
1939	// FIXME(vincenzopalazzo): move the HirId to a LocalDefId
1940	pub fn adjust_ident_and_get_scope(
1941	self,
1942	mut ident: Ident,
1943	scope: DefId,
1944	block: hir::HirId,
1945	) -> (Ident, DefId) {
1946	let scope = ident
1947	.span
1948	.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
1949	.and_then(\|actual_expansion\| actual_expansion.expn_data().parent_module)
1950	.unwrap_or_else(\|\| self.parent_module(block).to_def_id());
1951	(ident, scope)
1952	}
1953
1954	/// Checks whether this is a `const fn`. Returns `false` for non-functions.
1955	///
1956	/// Even if this returns `true`, constness may still be unstable!
1957	#[inline]
1958	pub fn is_const_fn(self, def_id: DefId) -> bool {
1959	matches!(
1960	self.def_kind(def_id),
1961	DefKind::Fn \| DefKind::AssocFn \| DefKind::Ctor(_, CtorKind::Fn) \| DefKind::Closure
1962	) && self.constness(def_id) == hir::Constness::Const
1963	}
1964
1965	/// Whether this item is conditionally constant for the purposes of the
1966	/// effects implementation.
1967	///
1968	/// This roughly corresponds to all const functions and other callable
1969	/// items, along with const impls and traits, and associated types within
1970	/// those impls and traits.
1971	pub fn is_conditionally_const(self, def_id: impl Into<DefId>) -> bool {
1972	let def_id: DefId = def_id.into();
1973	match self.def_kind(def_id) {
1974	DefKind::Impl { of_trait: `true` } => {
1975	let header = self.impl_trait_header(def_id).unwrap();
1976	header.constness == hir::Constness::Const
1977	&& self.is_const_trait(header.trait_ref.skip_binder().def_id)
1978	}
1979	DefKind::Fn \| DefKind::Ctor(_, CtorKind::Fn) => {
1980	self.constness(def_id) == hir::Constness::Const
1981	}
1982	DefKind::Trait => self.is_const_trait(def_id),
1983	DefKind::AssocTy => {
1984	let parent_def_id = self.parent(def_id);
1985	match self.def_kind(parent_def_id) {
1986	DefKind::Impl { of_trait: `false` } => `false`,
1987	DefKind::Impl { of_trait: `true` } \| DefKind::Trait => {
1988	self.is_conditionally_const(parent_def_id)
1989	}
1990	_ => bug!("unexpected parent item of associated type: {parent_def_id:?}"),
1991	}
1992	}
1993	DefKind::AssocFn => {
1994	let parent_def_id = self.parent(def_id);
1995	match self.def_kind(parent_def_id) {
1996	DefKind::Impl { of_trait: `false` } => {
1997	self.constness(def_id) == hir::Constness::Const
1998	}
1999	DefKind::Impl { of_trait: `true` } \| DefKind::Trait => {
2000	self.is_conditionally_const(parent_def_id)
2001	}
2002	_ => bug!("unexpected parent item of associated fn: {parent_def_id:?}"),
2003	}
2004	}
2005	DefKind::OpaqueTy => match self.opaque_ty_origin(def_id) {
2006	hir::OpaqueTyOrigin::FnReturn { parent, .. } => self.is_conditionally_const(parent),
2007	hir::OpaqueTyOrigin::AsyncFn { .. } => `false`,
2008	// FIXME(const_trait_impl): ATPITs could be conditionally const?
2009	hir::OpaqueTyOrigin::TyAlias { .. } => `false`,
2010	},
2011	DefKind::Closure => {
2012	// Closures and RPITs will eventually have const conditions
2013	// for `~const` bounds.
2014	`false`
2015	}
2016	DefKind::Ctor(_, CtorKind::Const)
2017	\| DefKind::Impl { of_trait: `false` }
2018	\| DefKind::Mod
2019	\| DefKind::Struct
2020	\| DefKind::Union
2021	\| DefKind::Enum
2022	\| DefKind::Variant
2023	\| DefKind::TyAlias
2024	\| DefKind::ForeignTy
2025	\| DefKind::TraitAlias
2026	\| DefKind::TyParam
2027	\| DefKind::Const
2028	\| DefKind::ConstParam
2029	\| DefKind::Static { .. }
2030	\| DefKind::AssocConst
2031	\| DefKind::Macro(_)
2032	\| DefKind::ExternCrate
2033	\| DefKind::Use
2034	\| DefKind::ForeignMod
2035	\| DefKind::AnonConst
2036	\| DefKind::InlineConst
2037	\| DefKind::Field
2038	\| DefKind::LifetimeParam
2039	\| DefKind::GlobalAsm
2040	\| DefKind::SyntheticCoroutineBody => `false`,
2041	}
2042	}
2043
2044	#[inline]
2045	pub fn is_const_trait(self, def_id: DefId) -> bool {
2046	self.trait_def(def_id).constness == hir::Constness::Const
2047	}
2048
2049	#[inline]
2050	pub fn is_const_default_method(self, def_id: DefId) -> bool {
2051	matches!(self.trait_of_item(def_id), Some(trait_id) if self.is_const_trait(trait_id))
2052	}
2053
2054	pub fn impl_method_has_trait_impl_trait_tys(self, def_id: DefId) -> bool {
2055	if self.def_kind(def_id) != DefKind::AssocFn {
2056	return `false`;
2057	}
2058
2059	let Some(item) = self.opt_associated_item(def_id) else {
2060	return `false`;
2061	};
2062	if item.container != ty::AssocItemContainer::Impl {
2063	return `false`;
2064	}
2065
2066	let Some(trait_item_def_id) = item.trait_item_def_id else {
2067	return `false`;
2068	};
2069
2070	return !self
2071	.associated_types_for_impl_traits_in_associated_fn(trait_item_def_id)
2072	.is_empty();
2073	}
2074	}
2075
2076	pub fn int_ty(ity: ast::IntTy) -> IntTy {
2077	match ity {
2078	ast::IntTy::Isize => IntTy::Isize,
2079	ast::IntTy::I8 => IntTy::I8,
2080	ast::IntTy::I16 => IntTy::I16,
2081	ast::IntTy::I32 => IntTy::I32,
2082	ast::IntTy::I64 => IntTy::I64,
2083	ast::IntTy::I128 => IntTy::I128,
2084	}
2085	}
2086
2087	pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2088	match uty {
2089	ast::UintTy::Usize => UintTy::Usize,
2090	ast::UintTy::U8 => UintTy::U8,
2091	ast::UintTy::U16 => UintTy::U16,
2092	ast::UintTy::U32 => UintTy::U32,
2093	ast::UintTy::U64 => UintTy::U64,
2094	ast::UintTy::U128 => UintTy::U128,
2095	}
2096	}
2097
2098	pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2099	match fty {
2100	ast::FloatTy::F16 => FloatTy::F16,
2101	ast::FloatTy::F32 => FloatTy::F32,
2102	ast::FloatTy::F64 => FloatTy::F64,
2103	ast::FloatTy::F128 => FloatTy::F128,
2104	}
2105	}
2106
2107	pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2108	match ity {
2109	IntTy::Isize => ast::IntTy::Isize,
2110	IntTy::I8 => ast::IntTy::I8,
2111	IntTy::I16 => ast::IntTy::I16,
2112	IntTy::I32 => ast::IntTy::I32,
2113	IntTy::I64 => ast::IntTy::I64,
2114	IntTy::I128 => ast::IntTy::I128,
2115	}
2116	}
2117
2118	pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2119	match uty {
2120	UintTy::Usize => ast::UintTy::Usize,
2121	UintTy::U8 => ast::UintTy::U8,
2122	UintTy::U16 => ast::UintTy::U16,
2123	UintTy::U32 => ast::UintTy::U32,
2124	UintTy::U64 => ast::UintTy::U64,
2125	UintTy::U128 => ast::UintTy::U128,
2126	}
2127	}
2128
2129	pub fn provide(providers: &mut Providers) {
2130	closure::provide(providers);
2131	context::provide(providers);
2132	erase_regions::provide(providers);
2133	inhabitedness::provide(providers);
2134	util::provide(providers);
2135	print::provide(providers);
2136	super::util::bug::provide(providers);
2137	*providers = Providers {
2138	trait_impls_of: trait_def::trait_impls_of_provider,
2139	incoherent_impls: trait_def::incoherent_impls_provider,
2140	trait_impls_in_crate: trait_def::trait_impls_in_crate_provider,
2141	traits: trait_def::traits_provider,
2142	vtable_allocation: vtable::vtable_allocation_provider,
2143	..*providers
2144	};
2145	}
2146
2147	/// A map for the local crate mapping each type to a vector of its
2148	/// inherent impls. This is not meant to be used outside of coherence;
2149	/// rather, you should request the vector for a specific type via
2150	/// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2151	/// (constructing this map requires touching the entire crate).
2152	#[derive(Clone, Debug, Default, HashStable)]
2153	pub struct CrateInherentImpls {
2154	pub inherent_impls: FxIndexMap<LocalDefId, Vec<DefId>>,
2155	pub incoherent_impls: FxIndexMap<SimplifiedType, Vec<LocalDefId>>,
2156	}
2157
2158	#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2159	pub struct SymbolName<'tcx> {
2160	/// `&str` gives a consistent ordering, which ensures reproducible builds.
2161	pub name: &'tcx str,
2162	}
2163
2164	impl<'tcx> SymbolName<'tcx> {
2165	pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2166	SymbolName { name: tcx.arena.alloc_str(string:name) }
2167	}
2168	}
2169
2170	impl<'tcx> fmt::Display for SymbolName<'tcx> {
2171	fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2172	fmt::Display::fmt(&self.name, f:fmt)
2173	}
2174	}
2175
2176	impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2177	fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2178	fmt::Display::fmt(&self.name, f:fmt)
2179	}
2180	}
2181
2182	#[derive(Debug, Default, Copy, Clone)]
2183	pub struct InferVarInfo {
2184	/// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2185	/// obligation, where:
2186	///
2187	/// `Foo` is not `Sized`*
2188	/// `(): Foo` may be satisfied*
2189	pub self_in_trait: bool,
2190	/// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2191	/// _>::AssocType = ?T`
2192	pub output: bool,
2193	}
2194
2195	/// The constituent parts of a type level constant of kind ADT or array.
2196	#[derive(Copy, Clone, Debug, HashStable)]
2197	pub struct DestructuredConst<'tcx> {
2198	pub variant: Option<VariantIdx>,
2199	pub fields: &'tcx [ty::Const<'tcx>],
2200	}
2201
2202	// Some types are used a lot. Make sure they don't unintentionally get bigger.
2203	#[cfg(target_pointer_width = "64")]
2204	mod size_asserts {
2205	use rustc_data_structures::static_assert_size;
2206
2207	use super::*;
2208	// tidy-alphabetical-start
2209	static_assert_size!(PredicateKind<'_>, `32`);
2210	static_assert_size!(WithCachedTypeInfo<TyKind<'_>>, `48`);
2211	// tidy-alphabetical-end
2212	}
2213