rustc_middle/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
14use std::assert_matches::assert_matches;
15use std::fmt::Debug;
16use std::hash::{Hash, Hasher};
17use std::marker::PhantomData;
18use std::num::NonZero;
19use std::ptr::NonNull;
20use std::{fmt, iter, str};
21
22pub use adt::*;
23pub use assoc::*;
24pub use generic_args::{GenericArgKind, TermKind, *};
25pub use generics::*;
26pub use intrinsic::IntrinsicDef;
27use rustc_abi::{Align, FieldIdx, Integer, IntegerType, ReprFlags, ReprOptions, VariantIdx};
28use rustc_ast::expand::StrippedCfgItem;
29use rustc_ast::node_id::NodeMap;
30pub use rustc_ast_ir::{Movability, Mutability, try_visit};
31use rustc_attr_data_structures::AttributeKind;
32use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
33use rustc_data_structures::intern::Interned;
34use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
35use rustc_data_structures::steal::Steal;
36use rustc_data_structures::unord::UnordMap;
37use rustc_errors::{Diag, ErrorGuaranteed};
38use rustc_hir::LangItem;
39use rustc_hir::def::{CtorKind, CtorOf, DefKind, DocLinkResMap, LifetimeRes, Res};
40use rustc_hir::def_id::{CrateNum, DefId, DefIdMap, LocalDefId, LocalDefIdMap};
41use rustc_hir::definitions::DisambiguatorState;
42use rustc_index::IndexVec;
43use rustc_index::bit_set::BitMatrix;
44use rustc_macros::{
45    Decodable, Encodable, HashStable, TyDecodable, TyEncodable, TypeFoldable, TypeVisitable,
46    extension,
47};
48use rustc_query_system::ich::StableHashingContext;
49use rustc_serialize::{Decodable, Encodable};
50use rustc_session::lint::LintBuffer;
51pub use rustc_session::lint::RegisteredTools;
52use rustc_span::hygiene::MacroKind;
53use rustc_span::{DUMMY_SP, ExpnId, ExpnKind, Ident, Span, Symbol, kw, sym};
54pub use rustc_type_ir::data_structures::{DelayedMap, DelayedSet};
55pub use rustc_type_ir::fast_reject::DeepRejectCtxt;
56#[allow(
57    hidden_glob_reexports,
58    rustc::usage_of_type_ir_inherent,
59    rustc::non_glob_import_of_type_ir_inherent
60)]
61use rustc_type_ir::inherent;
62pub use rustc_type_ir::relate::VarianceDiagInfo;
63pub use rustc_type_ir::solve::SizedTraitKind;
64pub use rustc_type_ir::*;
65#[allow(hidden_glob_reexports, unused_imports)]
66use rustc_type_ir::{InferCtxtLike, Interner};
67use tracing::{debug, instrument};
68pub use vtable::*;
69use {rustc_ast as ast, rustc_attr_data_structures as attr, rustc_hir as hir};
70
71pub use self::closure::{
72    BorrowKind, CAPTURE_STRUCT_LOCAL, CaptureInfo, CapturedPlace, ClosureTypeInfo,
73    MinCaptureInformationMap, MinCaptureList, RootVariableMinCaptureList, UpvarCapture, UpvarId,
74    UpvarPath, analyze_coroutine_closure_captures, is_ancestor_or_same_capture,
75    place_to_string_for_capture,
76};
77pub use self::consts::{
78    AnonConstKind, AtomicOrdering, Const, ConstInt, ConstKind, ConstToValTreeResult, Expr,
79    ExprKind, ScalarInt, UnevaluatedConst, ValTree, ValTreeKind, Value,
80};
81pub use self::context::{
82    CtxtInterners, CurrentGcx, DeducedParamAttrs, Feed, FreeRegionInfo, GlobalCtxt, Lift, TyCtxt,
83    TyCtxtFeed, tls,
84};
85pub use self::fold::*;
86pub use self::instance::{Instance, InstanceKind, ReifyReason, ShortInstance, UnusedGenericParams};
87pub use self::list::{List, ListWithCachedTypeInfo};
88pub use self::opaque_types::OpaqueTypeKey;
89pub use self::parameterized::ParameterizedOverTcx;
90pub use self::pattern::{Pattern, PatternKind};
91pub use self::predicate::{
92    AliasTerm, Clause, ClauseKind, CoercePredicate, ExistentialPredicate,
93    ExistentialPredicateStableCmpExt, ExistentialProjection, ExistentialTraitRef,
94    HostEffectPredicate, NormalizesTo, OutlivesPredicate, PolyCoercePredicate,
95    PolyExistentialPredicate, PolyExistentialProjection, PolyExistentialTraitRef,
96    PolyProjectionPredicate, PolyRegionOutlivesPredicate, PolySubtypePredicate, PolyTraitPredicate,
97    PolyTraitRef, PolyTypeOutlivesPredicate, Predicate, PredicateKind, ProjectionPredicate,
98    RegionOutlivesPredicate, SubtypePredicate, TraitPredicate, TraitRef, TypeOutlivesPredicate,
99};
100pub use self::region::{
101    BoundRegion, BoundRegionKind, EarlyParamRegion, LateParamRegion, LateParamRegionKind, Region,
102    RegionKind, RegionVid,
103};
104pub use self::rvalue_scopes::RvalueScopes;
105pub use self::sty::{
106    AliasTy, Article, Binder, BoundTy, BoundTyKind, BoundVariableKind, CanonicalPolyFnSig,
107    CoroutineArgsExt, EarlyBinder, FnSig, InlineConstArgs, InlineConstArgsParts, ParamConst,
108    ParamTy, PolyFnSig, TyKind, TypeAndMut, TypingMode, UpvarArgs,
109};
110pub use self::trait_def::TraitDef;
111pub use self::typeck_results::{
112    CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, IsIdentity,
113    Rust2024IncompatiblePatInfo, TypeckResults, UserType, UserTypeAnnotationIndex, UserTypeKind,
114};
115pub use self::visit::*;
116use crate::error::{OpaqueHiddenTypeMismatch, TypeMismatchReason};
117use crate::metadata::ModChild;
118use crate::middle::privacy::EffectiveVisibilities;
119use crate::mir::{Body, CoroutineLayout, CoroutineSavedLocal, SourceInfo};
120use crate::query::{IntoQueryParam, Providers};
121use crate::ty;
122use crate::ty::codec::{TyDecoder, TyEncoder};
123pub use crate::ty::diagnostics::*;
124use crate::ty::fast_reject::SimplifiedType;
125use crate::ty::layout::LayoutError;
126use crate::ty::util::Discr;
127use crate::ty::walk::TypeWalker;
128
129pub mod abstract_const;
130pub mod adjustment;
131pub mod cast;
132pub mod codec;
133pub mod error;
134pub mod fast_reject;
135pub mod inhabitedness;
136pub mod layout;
137pub mod normalize_erasing_regions;
138pub mod pattern;
139pub mod print;
140pub mod relate;
141pub mod significant_drop_order;
142pub mod trait_def;
143pub mod util;
144pub mod vtable;
145
146mod adt;
147mod assoc;
148mod closure;
149mod consts;
150mod context;
151mod diagnostics;
152mod elaborate_impl;
153mod erase_regions;
154mod fold;
155mod generic_args;
156mod generics;
157mod impls_ty;
158mod instance;
159mod intrinsic;
160mod list;
161mod opaque_types;
162mod parameterized;
163mod predicate;
164mod region;
165mod rvalue_scopes;
166mod structural_impls;
167#[allow(hidden_glob_reexports)]
168mod sty;
169mod typeck_results;
170mod visit;
171
172// Data types
173
174pub struct ResolverOutputs {
175    pub global_ctxt: ResolverGlobalCtxt,
176    pub ast_lowering: ResolverAstLowering,
177}
178
179#[derive(Debug)]
180pub struct ResolverGlobalCtxt {
181    pub visibilities_for_hashing: Vec<(LocalDefId, Visibility)>,
182    /// Item with a given `LocalDefId` was defined during macro expansion with ID `ExpnId`.
183    pub expn_that_defined: FxHashMap<LocalDefId, ExpnId>,
184    pub effective_visibilities: EffectiveVisibilities,
185    pub extern_crate_map: UnordMap<LocalDefId, CrateNum>,
186    pub maybe_unused_trait_imports: FxIndexSet<LocalDefId>,
187    pub module_children: LocalDefIdMap<Vec<ModChild>>,
188    pub glob_map: FxIndexMap<LocalDefId, FxIndexSet<Symbol>>,
189    pub main_def: Option<MainDefinition>,
190    pub trait_impls: FxIndexMap<DefId, Vec<LocalDefId>>,
191    /// A list of proc macro LocalDefIds, written out in the order in which
192    /// they are declared in the static array generated by proc_macro_harness.
193    pub proc_macros: Vec<LocalDefId>,
194    /// Mapping from ident span to path span for paths that don't exist as written, but that
195    /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
196    pub confused_type_with_std_module: FxIndexMap<Span, Span>,
197    pub doc_link_resolutions: FxIndexMap<LocalDefId, DocLinkResMap>,
198    pub doc_link_traits_in_scope: FxIndexMap<LocalDefId, Vec<DefId>>,
199    pub all_macro_rules: FxHashSet<Symbol>,
200    pub stripped_cfg_items: Steal<Vec<StrippedCfgItem>>,
201}
202
203/// Resolutions that should only be used for lowering.
204/// This struct is meant to be consumed by lowering.
205#[derive(Debug)]
206pub struct ResolverAstLowering {
207    pub legacy_const_generic_args: FxHashMap<DefId, Option<Vec<usize>>>,
208
209    /// Resolutions for nodes that have a single resolution.
210    pub partial_res_map: NodeMap<hir::def::PartialRes>,
211    /// Resolutions for import nodes, which have multiple resolutions in different namespaces.
212    pub import_res_map: NodeMap<hir::def::PerNS<Option<Res<ast::NodeId>>>>,
213    /// Resolutions for labels (node IDs of their corresponding blocks or loops).
214    pub label_res_map: NodeMap<ast::NodeId>,
215    /// Resolutions for lifetimes.
216    pub lifetimes_res_map: NodeMap<LifetimeRes>,
217    /// Lifetime parameters that lowering will have to introduce.
218    pub extra_lifetime_params_map: NodeMap<Vec<(Ident, ast::NodeId, LifetimeRes)>>,
219
220    pub next_node_id: ast::NodeId,
221
222    pub node_id_to_def_id: NodeMap<LocalDefId>,
223
224    pub disambiguator: DisambiguatorState,
225
226    pub trait_map: NodeMap<Vec<hir::TraitCandidate>>,
227    /// List functions and methods for which lifetime elision was successful.
228    pub lifetime_elision_allowed: FxHashSet<ast::NodeId>,
229
230    /// Lints that were emitted by the resolver and early lints.
231    pub lint_buffer: Steal<LintBuffer>,
232
233    /// Information about functions signatures for delegation items expansion
234    pub delegation_fn_sigs: LocalDefIdMap<DelegationFnSig>,
235}
236
237#[derive(Debug)]
238pub struct DelegationFnSig {
239    pub header: ast::FnHeader,
240    pub param_count: usize,
241    pub has_self: bool,
242    pub c_variadic: bool,
243    pub target_feature: bool,
244}
245
246#[derive(Clone, Copy, Debug)]
247pub struct MainDefinition {
248    pub res: Res<ast::NodeId>,
249    pub is_import: bool,
250    pub span: Span,
251}
252
253impl MainDefinition {
254    pub fn opt_fn_def_id(self) -> Option<DefId> {
255        if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
256    }
257}
258
259/// The "header" of an impl is everything outside the body: a Self type, a trait
260/// ref (in the case of a trait impl), and a set of predicates (from the
261/// bounds / where-clauses).
262#[derive(Clone, Debug, TypeFoldable, TypeVisitable)]
263pub struct ImplHeader<'tcx> {
264    pub impl_def_id: DefId,
265    pub impl_args: ty::GenericArgsRef<'tcx>,
266    pub self_ty: Ty<'tcx>,
267    pub trait_ref: Option<TraitRef<'tcx>>,
268    pub predicates: Vec<Predicate<'tcx>>,
269}
270
271#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable)]
272pub struct ImplTraitHeader<'tcx> {
273    pub trait_ref: ty::EarlyBinder<'tcx, ty::TraitRef<'tcx>>,
274    pub polarity: ImplPolarity,
275    pub safety: hir::Safety,
276    pub constness: hir::Constness,
277}
278
279#[derive(Copy, Clone, PartialEq, Eq, Debug, TypeFoldable, TypeVisitable)]
280pub enum ImplSubject<'tcx> {
281    Trait(TraitRef<'tcx>),
282    Inherent(Ty<'tcx>),
283}
284
285#[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, HashStable, Debug)]
286#[derive(TypeFoldable, TypeVisitable)]
287pub enum Asyncness {
288    Yes,
289    No,
290}
291
292impl Asyncness {
293    pub fn is_async(self) -> bool {
294        matches!(self, Asyncness::Yes)
295    }
296}
297
298#[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, Encodable, Decodable, HashStable)]
299pub enum Visibility<Id = LocalDefId> {
300    /// Visible everywhere (including in other crates).
301    Public,
302    /// Visible only in the given crate-local module.
303    Restricted(Id),
304}
305
306impl Visibility {
307    pub fn to_string(self, def_id: LocalDefId, tcx: TyCtxt<'_>) -> String {
308        match self {
309            ty::Visibility::Restricted(restricted_id) => {
310                if restricted_id.is_top_level_module() {
311                    "pub(crate)".to_string()
312                } else if restricted_id == tcx.parent_module_from_def_id(def_id).to_local_def_id() {
313                    "pub(self)".to_string()
314                } else {
315                    format!(
316                        "pub(in crate{})",
317                        tcx.def_path(restricted_id.to_def_id()).to_string_no_crate_verbose()
318                    )
319                }
320            }
321            ty::Visibility::Public => "pub".to_string(),
322        }
323    }
324}
325
326#[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
327#[derive(TypeFoldable, TypeVisitable)]
328pub struct ClosureSizeProfileData<'tcx> {
329    /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
330    pub before_feature_tys: Ty<'tcx>,
331    /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
332    pub after_feature_tys: Ty<'tcx>,
333}
334
335impl TyCtxt<'_> {
336    #[inline]
337    pub fn opt_parent(self, id: DefId) -> Option<DefId> {
338        self.def_key(id).parent.map(|index| DefId { index, ..id })
339    }
340
341    #[inline]
342    #[track_caller]
343    pub fn parent(self, id: DefId) -> DefId {
344        match self.opt_parent(id) {
345            Some(id) => id,
346            // not `unwrap_or_else` to avoid breaking caller tracking
347            None => bug!("{id:?} doesn't have a parent"),
348        }
349    }
350
351    #[inline]
352    #[track_caller]
353    pub fn opt_local_parent(self, id: LocalDefId) -> Option<LocalDefId> {
354        self.opt_parent(id.to_def_id()).map(DefId::expect_local)
355    }
356
357    #[inline]
358    #[track_caller]
359    pub fn local_parent(self, id: impl Into<LocalDefId>) -> LocalDefId {
360        self.parent(id.into().to_def_id()).expect_local()
361    }
362
363    pub fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
364        if descendant.krate != ancestor.krate {
365            return false;
366        }
367
368        while descendant != ancestor {
369            match self.opt_parent(descendant) {
370                Some(parent) => descendant = parent,
371                None => return false,
372            }
373        }
374        true
375    }
376}
377
378impl<Id> Visibility<Id> {
379    pub fn is_public(self) -> bool {
380        matches!(self, Visibility::Public)
381    }
382
383    pub fn map_id<OutId>(self, f: impl FnOnce(Id) -> OutId) -> Visibility<OutId> {
384        match self {
385            Visibility::Public => Visibility::Public,
386            Visibility::Restricted(id) => Visibility::Restricted(f(id)),
387        }
388    }
389}
390
391impl<Id: Into<DefId>> Visibility<Id> {
392    pub fn to_def_id(self) -> Visibility<DefId> {
393        self.map_id(Into::into)
394    }
395
396    /// Returns `true` if an item with this visibility is accessible from the given module.
397    pub fn is_accessible_from(self, module: impl Into<DefId>, tcx: TyCtxt<'_>) -> bool {
398        match self {
399            // Public items are visible everywhere.
400            Visibility::Public => true,
401            Visibility::Restricted(id) => tcx.is_descendant_of(module.into(), id.into()),
402        }
403    }
404
405    /// Returns `true` if this visibility is at least as accessible as the given visibility
406    pub fn is_at_least(self, vis: Visibility<impl Into<DefId>>, tcx: TyCtxt<'_>) -> bool {
407        match vis {
408            Visibility::Public => self.is_public(),
409            Visibility::Restricted(id) => self.is_accessible_from(id, tcx),
410        }
411    }
412}
413
414impl Visibility<DefId> {
415    pub fn expect_local(self) -> Visibility {
416        self.map_id(|id| id.expect_local())
417    }
418
419    /// Returns `true` if this item is visible anywhere in the local crate.
420    pub fn is_visible_locally(self) -> bool {
421        match self {
422            Visibility::Public => true,
423            Visibility::Restricted(def_id) => def_id.is_local(),
424        }
425    }
426}
427
428/// The crate variances map is computed during typeck and contains the
429/// variance of every item in the local crate. You should not use it
430/// directly, because to do so will make your pass dependent on the
431/// HIR of every item in the local crate. Instead, use
432/// `tcx.variances_of()` to get the variance for a *particular*
433/// item.
434#[derive(HashStable, Debug)]
435pub struct CrateVariancesMap<'tcx> {
436    /// For each item with generics, maps to a vector of the variance
437    /// of its generics. If an item has no generics, it will have no
438    /// entry.
439    pub variances: DefIdMap<&'tcx [ty::Variance]>,
440}
441
442// Contains information needed to resolve types and (in the future) look up
443// the types of AST nodes.
444#[derive(Copy, Clone, PartialEq, Eq, Hash)]
445pub struct CReaderCacheKey {
446    pub cnum: Option<CrateNum>,
447    pub pos: usize,
448}
449
450/// Use this rather than `TyKind`, whenever possible.
451#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable)]
452#[rustc_diagnostic_item = "Ty"]
453#[rustc_pass_by_value]
454pub struct Ty<'tcx>(Interned<'tcx, WithCachedTypeInfo<TyKind<'tcx>>>);
455
456impl<'tcx> rustc_type_ir::inherent::IntoKind for Ty<'tcx> {
457    type Kind = TyKind<'tcx>;
458
459    fn kind(self) -> TyKind<'tcx> {
460        *self.kind()
461    }
462}
463
464impl<'tcx> rustc_type_ir::Flags for Ty<'tcx> {
465    fn flags(&self) -> TypeFlags {
466        self.0.flags
467    }
468
469    fn outer_exclusive_binder(&self) -> DebruijnIndex {
470        self.0.outer_exclusive_binder
471    }
472}
473
474impl EarlyParamRegion {
475    /// Does this early bound region have a name? Early bound regions normally
476    /// always have names except when using anonymous lifetimes (`'_`).
477    pub fn has_name(&self) -> bool {
478        self.name != kw::UnderscoreLifetime
479    }
480}
481
482/// The crate outlives map is computed during typeck and contains the
483/// outlives of every item in the local crate. You should not use it
484/// directly, because to do so will make your pass dependent on the
485/// HIR of every item in the local crate. Instead, use
486/// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
487/// item.
488#[derive(HashStable, Debug)]
489pub struct CratePredicatesMap<'tcx> {
490    /// For each struct with outlive bounds, maps to a vector of the
491    /// predicate of its outlive bounds. If an item has no outlives
492    /// bounds, it will have no entry.
493    pub predicates: DefIdMap<&'tcx [(Clause<'tcx>, Span)]>,
494}
495
496#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
497pub struct Term<'tcx> {
498    ptr: NonNull<()>,
499    marker: PhantomData<(Ty<'tcx>, Const<'tcx>)>,
500}
501
502impl<'tcx> rustc_type_ir::inherent::Term<TyCtxt<'tcx>> for Term<'tcx> {}
503
504impl<'tcx> rustc_type_ir::inherent::IntoKind for Term<'tcx> {
505    type Kind = TermKind<'tcx>;
506
507    fn kind(self) -> Self::Kind {
508        self.kind()
509    }
510}
511
512unsafe impl<'tcx> rustc_data_structures::sync::DynSend for Term<'tcx> where
513    &'tcx (Ty<'tcx>, Const<'tcx>): rustc_data_structures::sync::DynSend
514{
515}
516unsafe impl<'tcx> rustc_data_structures::sync::DynSync for Term<'tcx> where
517    &'tcx (Ty<'tcx>, Const<'tcx>): rustc_data_structures::sync::DynSync
518{
519}
520unsafe impl<'tcx> Send for Term<'tcx> where &'tcx (Ty<'tcx>, Const<'tcx>): Send {}
521unsafe impl<'tcx> Sync for Term<'tcx> where &'tcx (Ty<'tcx>, Const<'tcx>): Sync {}
522
523impl Debug for Term<'_> {
524    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
525        match self.kind() {
526            TermKind::Ty(ty) => write!(f, "Term::Ty({ty:?})"),
527            TermKind::Const(ct) => write!(f, "Term::Const({ct:?})"),
528        }
529    }
530}
531
532impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
533    fn from(ty: Ty<'tcx>) -> Self {
534        TermKind::Ty(ty).pack()
535    }
536}
537
538impl<'tcx> From<Const<'tcx>> for Term<'tcx> {
539    fn from(c: Const<'tcx>) -> Self {
540        TermKind::Const(c).pack()
541    }
542}
543
544impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Term<'tcx> {
545    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
546        self.kind().hash_stable(hcx, hasher);
547    }
548}
549
550impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for Term<'tcx> {
551    fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
552        self,
553        folder: &mut F,
554    ) -> Result<Self, F::Error> {
555        match self.kind() {
556            ty::TermKind::Ty(ty) => ty.try_fold_with(folder).map(Into::into),
557            ty::TermKind::Const(ct) => ct.try_fold_with(folder).map(Into::into),
558        }
559    }
560
561    fn fold_with<F: TypeFolder<TyCtxt<'tcx>>>(self, folder: &mut F) -> Self {
562        match self.kind() {
563            ty::TermKind::Ty(ty) => ty.fold_with(folder).into(),
564            ty::TermKind::Const(ct) => ct.fold_with(folder).into(),
565        }
566    }
567}
568
569impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for Term<'tcx> {
570    fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(&self, visitor: &mut V) -> V::Result {
571        match self.kind() {
572            ty::TermKind::Ty(ty) => ty.visit_with(visitor),
573            ty::TermKind::Const(ct) => ct.visit_with(visitor),
574        }
575    }
576}
577
578impl<'tcx, E: TyEncoder<'tcx>> Encodable<E> for Term<'tcx> {
579    fn encode(&self, e: &mut E) {
580        self.kind().encode(e)
581    }
582}
583
584impl<'tcx, D: TyDecoder<'tcx>> Decodable<D> for Term<'tcx> {
585    fn decode(d: &mut D) -> Self {
586        let res: TermKind<'tcx> = Decodable::decode(d);
587        res.pack()
588    }
589}
590
591impl<'tcx> Term<'tcx> {
592    #[inline]
593    pub fn kind(self) -> TermKind<'tcx> {
594        let ptr =
595            unsafe { self.ptr.map_addr(|addr| NonZero::new_unchecked(addr.get() & !TAG_MASK)) };
596        // SAFETY: use of `Interned::new_unchecked` here is ok because these
597        // pointers were originally created from `Interned` types in `pack()`,
598        // and this is just going in the other direction.
599        unsafe {
600            match self.ptr.addr().get() & TAG_MASK {
601                TYPE_TAG => TermKind::Ty(Ty(Interned::new_unchecked(
602                    ptr.cast::<WithCachedTypeInfo<ty::TyKind<'tcx>>>().as_ref(),
603                ))),
604                CONST_TAG => TermKind::Const(ty::Const(Interned::new_unchecked(
605                    ptr.cast::<WithCachedTypeInfo<ty::ConstKind<'tcx>>>().as_ref(),
606                ))),
607                _ => core::intrinsics::unreachable(),
608            }
609        }
610    }
611
612    pub fn as_type(&self) -> Option<Ty<'tcx>> {
613        if let TermKind::Ty(ty) = self.kind() { Some(ty) } else { None }
614    }
615
616    pub fn expect_type(&self) -> Ty<'tcx> {
617        self.as_type().expect("expected a type, but found a const")
618    }
619
620    pub fn as_const(&self) -> Option<Const<'tcx>> {
621        if let TermKind::Const(c) = self.kind() { Some(c) } else { None }
622    }
623
624    pub fn expect_const(&self) -> Const<'tcx> {
625        self.as_const().expect("expected a const, but found a type")
626    }
627
628    pub fn into_arg(self) -> GenericArg<'tcx> {
629        match self.kind() {
630            TermKind::Ty(ty) => ty.into(),
631            TermKind::Const(c) => c.into(),
632        }
633    }
634
635    pub fn to_alias_term(self) -> Option<AliasTerm<'tcx>> {
636        match self.kind() {
637            TermKind::Ty(ty) => match *ty.kind() {
638                ty::Alias(_kind, alias_ty) => Some(alias_ty.into()),
639                _ => None,
640            },
641            TermKind::Const(ct) => match ct.kind() {
642                ConstKind::Unevaluated(uv) => Some(uv.into()),
643                _ => None,
644            },
645        }
646    }
647
648    pub fn is_infer(&self) -> bool {
649        match self.kind() {
650            TermKind::Ty(ty) => ty.is_ty_var(),
651            TermKind::Const(ct) => ct.is_ct_infer(),
652        }
653    }
654
655    pub fn is_trivially_wf(&self, tcx: TyCtxt<'tcx>) -> bool {
656        match self.kind() {
657            TermKind::Ty(ty) => ty.is_trivially_wf(tcx),
658            TermKind::Const(ct) => ct.is_trivially_wf(),
659        }
660    }
661
662    /// Iterator that walks `self` and any types reachable from
663    /// `self`, in depth-first order. Note that just walks the types
664    /// that appear in `self`, it does not descend into the fields of
665    /// structs or variants. For example:
666    ///
667    /// ```text
668    /// isize => { isize }
669    /// Foo<Bar<isize>> => { Foo<Bar<isize>>, Bar<isize>, isize }
670    /// [isize] => { [isize], isize }
671    /// ```
672    pub fn walk(self) -> TypeWalker<TyCtxt<'tcx>> {
673        TypeWalker::new(self.into())
674    }
675}
676
677const TAG_MASK: usize = 0b11;
678const TYPE_TAG: usize = 0b00;
679const CONST_TAG: usize = 0b01;
680
681#[extension(pub trait TermKindPackExt<'tcx>)]
682impl<'tcx> TermKind<'tcx> {
683    #[inline]
684    fn pack(self) -> Term<'tcx> {
685        let (tag, ptr) = match self {
686            TermKind::Ty(ty) => {
687                // Ensure we can use the tag bits.
688                assert_eq!(align_of_val(&*ty.0.0) & TAG_MASK, 0);
689                (TYPE_TAG, NonNull::from(ty.0.0).cast())
690            }
691            TermKind::Const(ct) => {
692                // Ensure we can use the tag bits.
693                assert_eq!(align_of_val(&*ct.0.0) & TAG_MASK, 0);
694                (CONST_TAG, NonNull::from(ct.0.0).cast())
695            }
696        };
697
698        Term { ptr: ptr.map_addr(|addr| addr | tag), marker: PhantomData }
699    }
700}
701
702#[derive(Copy, Clone, PartialEq, Eq, Debug)]
703pub enum ParamTerm {
704    Ty(ParamTy),
705    Const(ParamConst),
706}
707
708impl ParamTerm {
709    pub fn index(self) -> usize {
710        match self {
711            ParamTerm::Ty(ty) => ty.index as usize,
712            ParamTerm::Const(ct) => ct.index as usize,
713        }
714    }
715}
716
717#[derive(Copy, Clone, Eq, PartialEq, Debug)]
718pub enum TermVid {
719    Ty(ty::TyVid),
720    Const(ty::ConstVid),
721}
722
723impl From<ty::TyVid> for TermVid {
724    fn from(value: ty::TyVid) -> Self {
725        TermVid::Ty(value)
726    }
727}
728
729impl From<ty::ConstVid> for TermVid {
730    fn from(value: ty::ConstVid) -> Self {
731        TermVid::Const(value)
732    }
733}
734
735/// Represents the bounds declared on a particular set of type
736/// parameters. Should eventually be generalized into a flag list of
737/// where-clauses. You can obtain an `InstantiatedPredicates` list from a
738/// `GenericPredicates` by using the `instantiate` method. Note that this method
739/// reflects an important semantic invariant of `InstantiatedPredicates`: while
740/// the `GenericPredicates` are expressed in terms of the bound type
741/// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
742/// represented a set of bounds for some particular instantiation,
743/// meaning that the generic parameters have been instantiated with
744/// their values.
745///
746/// Example:
747/// ```ignore (illustrative)
748/// struct Foo<T, U: Bar<T>> { ... }
749/// ```
750/// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
751/// `[[], [U:Bar<T>]]`. Now if there were some particular reference
752/// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
753/// [usize:Bar<isize>]]`.
754#[derive(Clone, Debug, TypeFoldable, TypeVisitable)]
755pub struct InstantiatedPredicates<'tcx> {
756    pub predicates: Vec<Clause<'tcx>>,
757    pub spans: Vec<Span>,
758}
759
760impl<'tcx> InstantiatedPredicates<'tcx> {
761    pub fn empty() -> InstantiatedPredicates<'tcx> {
762        InstantiatedPredicates { predicates: vec![], spans: vec![] }
763    }
764
765    pub fn is_empty(&self) -> bool {
766        self.predicates.is_empty()
767    }
768
769    pub fn iter(&self) -> <&Self as IntoIterator>::IntoIter {
770        self.into_iter()
771    }
772}
773
774impl<'tcx> IntoIterator for InstantiatedPredicates<'tcx> {
775    type Item = (Clause<'tcx>, Span);
776
777    type IntoIter = std::iter::Zip<std::vec::IntoIter<Clause<'tcx>>, std::vec::IntoIter<Span>>;
778
779    fn into_iter(self) -> Self::IntoIter {
780        debug_assert_eq!(self.predicates.len(), self.spans.len());
781        std::iter::zip(self.predicates, self.spans)
782    }
783}
784
785impl<'a, 'tcx> IntoIterator for &'a InstantiatedPredicates<'tcx> {
786    type Item = (Clause<'tcx>, Span);
787
788    type IntoIter = std::iter::Zip<
789        std::iter::Copied<std::slice::Iter<'a, Clause<'tcx>>>,
790        std::iter::Copied<std::slice::Iter<'a, Span>>,
791    >;
792
793    fn into_iter(self) -> Self::IntoIter {
794        debug_assert_eq!(self.predicates.len(), self.spans.len());
795        std::iter::zip(self.predicates.iter().copied(), self.spans.iter().copied())
796    }
797}
798
799#[derive(Copy, Clone, Debug, TypeFoldable, TypeVisitable, HashStable, TyEncodable, TyDecodable)]
800pub struct OpaqueHiddenType<'tcx> {
801    /// The span of this particular definition of the opaque type. So
802    /// for example:
803    ///
804    /// ```ignore (incomplete snippet)
805    /// type Foo = impl Baz;
806    /// fn bar() -> Foo {
807    /// //          ^^^ This is the span we are looking for!
808    /// }
809    /// ```
810    ///
811    /// In cases where the fn returns `(impl Trait, impl Trait)` or
812    /// other such combinations, the result is currently
813    /// over-approximated, but better than nothing.
814    pub span: Span,
815
816    /// The type variable that represents the value of the opaque type
817    /// that we require. In other words, after we compile this function,
818    /// we will be created a constraint like:
819    /// ```ignore (pseudo-rust)
820    /// Foo<'a, T> = ?C
821    /// ```
822    /// where `?C` is the value of this type variable. =) It may
823    /// naturally refer to the type and lifetime parameters in scope
824    /// in this function, though ultimately it should only reference
825    /// those that are arguments to `Foo` in the constraint above. (In
826    /// other words, `?C` should not include `'b`, even though it's a
827    /// lifetime parameter on `foo`.)
828    pub ty: Ty<'tcx>,
829}
830
831/// Whether we're currently in HIR typeck or MIR borrowck.
832#[derive(Debug, Clone, Copy)]
833pub enum DefiningScopeKind {
834    /// During writeback in typeck, we don't care about regions and simply
835    /// erase them. This means we also don't check whether regions are
836    /// universal in the opaque type key. This will only be checked in
837    /// MIR borrowck.
838    HirTypeck,
839    MirBorrowck,
840}
841
842impl<'tcx> OpaqueHiddenType<'tcx> {
843    pub fn new_error(tcx: TyCtxt<'tcx>, guar: ErrorGuaranteed) -> OpaqueHiddenType<'tcx> {
844        OpaqueHiddenType { span: DUMMY_SP, ty: Ty::new_error(tcx, guar) }
845    }
846
847    pub fn build_mismatch_error(
848        &self,
849        other: &Self,
850        tcx: TyCtxt<'tcx>,
851    ) -> Result<Diag<'tcx>, ErrorGuaranteed> {
852        (self.ty, other.ty).error_reported()?;
853        // Found different concrete types for the opaque type.
854        let sub_diag = if self.span == other.span {
855            TypeMismatchReason::ConflictType { span: self.span }
856        } else {
857            TypeMismatchReason::PreviousUse { span: self.span }
858        };
859        Ok(tcx.dcx().create_err(OpaqueHiddenTypeMismatch {
860            self_ty: self.ty,
861            other_ty: other.ty,
862            other_span: other.span,
863            sub: sub_diag,
864        }))
865    }
866
867    #[instrument(level = "debug", skip(tcx), ret)]
868    pub fn remap_generic_params_to_declaration_params(
869        self,
870        opaque_type_key: OpaqueTypeKey<'tcx>,
871        tcx: TyCtxt<'tcx>,
872        defining_scope_kind: DefiningScopeKind,
873    ) -> Self {
874        let OpaqueTypeKey { def_id, args } = opaque_type_key;
875
876        // Use args to build up a reverse map from regions to their
877        // identity mappings. This is necessary because of `impl
878        // Trait` lifetimes are computed by replacing existing
879        // lifetimes with 'static and remapping only those used in the
880        // `impl Trait` return type, resulting in the parameters
881        // shifting.
882        let id_args = GenericArgs::identity_for_item(tcx, def_id);
883        debug!(?id_args);
884
885        // This zip may have several times the same lifetime in `args` paired with a different
886        // lifetime from `id_args`. Simply `collect`ing the iterator is the correct behaviour:
887        // it will pick the last one, which is the one we introduced in the impl-trait desugaring.
888        let map = args.iter().zip(id_args).collect();
889        debug!("map = {:#?}", map);
890
891        // Convert the type from the function into a type valid outside by mapping generic
892        // parameters to into the context of the opaque.
893        //
894        // We erase regions when doing this during HIR typeck.
895        let this = match defining_scope_kind {
896            DefiningScopeKind::HirTypeck => tcx.erase_regions(self),
897            DefiningScopeKind::MirBorrowck => self,
898        };
899        let result = this.fold_with(&mut opaque_types::ReverseMapper::new(tcx, map, self.span));
900        if cfg!(debug_assertions) && matches!(defining_scope_kind, DefiningScopeKind::HirTypeck) {
901            assert_eq!(result.ty, tcx.erase_regions(result.ty));
902        }
903        result
904    }
905}
906
907/// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
908/// identified by both a universe, as well as a name residing within that universe. Distinct bound
909/// regions/types/consts within the same universe simply have an unknown relationship to one
910/// another.
911#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
912#[derive(HashStable, TyEncodable, TyDecodable)]
913pub struct Placeholder<T> {
914    pub universe: UniverseIndex,
915    pub bound: T,
916}
917
918pub type PlaceholderRegion = Placeholder<BoundRegion>;
919
920impl<'tcx> rustc_type_ir::inherent::PlaceholderLike<TyCtxt<'tcx>> for PlaceholderRegion {
921    type Bound = BoundRegion;
922
923    fn universe(self) -> UniverseIndex {
924        self.universe
925    }
926
927    fn var(self) -> BoundVar {
928        self.bound.var
929    }
930
931    fn with_updated_universe(self, ui: UniverseIndex) -> Self {
932        Placeholder { universe: ui, ..self }
933    }
934
935    fn new(ui: UniverseIndex, bound: BoundRegion) -> Self {
936        Placeholder { universe: ui, bound }
937    }
938
939    fn new_anon(ui: UniverseIndex, var: BoundVar) -> Self {
940        Placeholder { universe: ui, bound: BoundRegion { var, kind: BoundRegionKind::Anon } }
941    }
942}
943
944pub type PlaceholderType = Placeholder<BoundTy>;
945
946impl<'tcx> rustc_type_ir::inherent::PlaceholderLike<TyCtxt<'tcx>> for PlaceholderType {
947    type Bound = BoundTy;
948
949    fn universe(self) -> UniverseIndex {
950        self.universe
951    }
952
953    fn var(self) -> BoundVar {
954        self.bound.var
955    }
956
957    fn with_updated_universe(self, ui: UniverseIndex) -> Self {
958        Placeholder { universe: ui, ..self }
959    }
960
961    fn new(ui: UniverseIndex, bound: BoundTy) -> Self {
962        Placeholder { universe: ui, bound }
963    }
964
965    fn new_anon(ui: UniverseIndex, var: BoundVar) -> Self {
966        Placeholder { universe: ui, bound: BoundTy { var, kind: BoundTyKind::Anon } }
967    }
968}
969
970#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
971#[derive(TyEncodable, TyDecodable)]
972pub struct BoundConst<'tcx> {
973    pub var: BoundVar,
974    pub ty: Ty<'tcx>,
975}
976
977pub type PlaceholderConst = Placeholder<BoundVar>;
978
979impl<'tcx> rustc_type_ir::inherent::PlaceholderLike<TyCtxt<'tcx>> for PlaceholderConst {
980    type Bound = BoundVar;
981
982    fn universe(self) -> UniverseIndex {
983        self.universe
984    }
985
986    fn var(self) -> BoundVar {
987        self.bound
988    }
989
990    fn with_updated_universe(self, ui: UniverseIndex) -> Self {
991        Placeholder { universe: ui, ..self }
992    }
993
994    fn new(ui: UniverseIndex, bound: BoundVar) -> Self {
995        Placeholder { universe: ui, bound }
996    }
997
998    fn new_anon(ui: UniverseIndex, var: BoundVar) -> Self {
999        Placeholder { universe: ui, bound: var }
1000    }
1001}
1002
1003pub type Clauses<'tcx> = &'tcx ListWithCachedTypeInfo<Clause<'tcx>>;
1004
1005impl<'tcx> rustc_type_ir::Flags for Clauses<'tcx> {
1006    fn flags(&self) -> TypeFlags {
1007        (**self).flags()
1008    }
1009
1010    fn outer_exclusive_binder(&self) -> DebruijnIndex {
1011        (**self).outer_exclusive_binder()
1012    }
1013}
1014
1015/// When interacting with the type system we must provide information about the
1016/// environment. `ParamEnv` is the type that represents this information. See the
1017/// [dev guide chapter][param_env_guide] for more information.
1018///
1019/// [param_env_guide]: https://rustc-dev-guide.rust-lang.org/typing_parameter_envs.html
1020#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
1021#[derive(HashStable, TypeVisitable, TypeFoldable)]
1022pub struct ParamEnv<'tcx> {
1023    /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1024    /// basically the set of bounds on the in-scope type parameters, translated
1025    /// into `Obligation`s, and elaborated and normalized.
1026    ///
1027    /// Use the `caller_bounds()` method to access.
1028    caller_bounds: Clauses<'tcx>,
1029}
1030
1031impl<'tcx> rustc_type_ir::inherent::ParamEnv<TyCtxt<'tcx>> for ParamEnv<'tcx> {
1032    fn caller_bounds(self) -> impl inherent::SliceLike<Item = ty::Clause<'tcx>> {
1033        self.caller_bounds()
1034    }
1035}
1036
1037impl<'tcx> ParamEnv<'tcx> {
1038    /// Construct a trait environment suitable for contexts where there are
1039    /// no where-clauses in scope. In the majority of cases it is incorrect
1040    /// to use an empty environment. See the [dev guide section][param_env_guide]
1041    /// for information on what a `ParamEnv` is and how to acquire one.
1042    ///
1043    /// [param_env_guide]: https://rustc-dev-guide.rust-lang.org/typing_parameter_envs.html
1044    #[inline]
1045    pub fn empty() -> Self {
1046        Self::new(ListWithCachedTypeInfo::empty())
1047    }
1048
1049    #[inline]
1050    pub fn caller_bounds(self) -> Clauses<'tcx> {
1051        self.caller_bounds
1052    }
1053
1054    /// Construct a trait environment with the given set of predicates.
1055    #[inline]
1056    pub fn new(caller_bounds: Clauses<'tcx>) -> Self {
1057        ParamEnv { caller_bounds }
1058    }
1059
1060    /// Creates a pair of param-env and value for use in queries.
1061    pub fn and<T: TypeVisitable<TyCtxt<'tcx>>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1062        ParamEnvAnd { param_env: self, value }
1063    }
1064}
1065
1066#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable, TypeVisitable)]
1067#[derive(HashStable)]
1068pub struct ParamEnvAnd<'tcx, T> {
1069    pub param_env: ParamEnv<'tcx>,
1070    pub value: T,
1071}
1072
1073impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1074    pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1075        (self.param_env, self.value)
1076    }
1077}
1078
1079/// The environment in which to do trait solving.
1080///
1081/// Most of the time you only need to care about the `ParamEnv`
1082/// as the `TypingMode` is simply stored in the `InferCtxt`.
1083///
1084/// However, there are some places which rely on trait solving
1085/// without using an `InferCtxt` themselves. For these to be
1086/// able to use the trait system they have to be able to initialize
1087/// such an `InferCtxt` with the right `typing_mode`, so they need
1088/// to track both.
1089#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1090#[derive(TypeVisitable, TypeFoldable)]
1091pub struct TypingEnv<'tcx> {
1092    pub typing_mode: TypingMode<'tcx>,
1093    pub param_env: ParamEnv<'tcx>,
1094}
1095
1096impl<'tcx> TypingEnv<'tcx> {
1097    /// Create a typing environment with no where-clauses in scope
1098    /// where all opaque types and default associated items are revealed.
1099    ///
1100    /// This is only suitable for monomorphized, post-typeck environments.
1101    /// Do not use this for MIR optimizations, as even though they also
1102    /// use `TypingMode::PostAnalysis`, they may still have where-clauses
1103    /// in scope.
1104    pub fn fully_monomorphized() -> TypingEnv<'tcx> {
1105        TypingEnv { typing_mode: TypingMode::PostAnalysis, param_env: ParamEnv::empty() }
1106    }
1107
1108    /// Create a typing environment for use during analysis outside of a body.
1109    ///
1110    /// Using a typing environment inside of bodies is not supported as the body
1111    /// may define opaque types. In this case the used functions have to be
1112    /// converted to use proper canonical inputs instead.
1113    pub fn non_body_analysis(
1114        tcx: TyCtxt<'tcx>,
1115        def_id: impl IntoQueryParam<DefId>,
1116    ) -> TypingEnv<'tcx> {
1117        TypingEnv { typing_mode: TypingMode::non_body_analysis(), param_env: tcx.param_env(def_id) }
1118    }
1119
1120    pub fn post_analysis(tcx: TyCtxt<'tcx>, def_id: impl IntoQueryParam<DefId>) -> TypingEnv<'tcx> {
1121        tcx.typing_env_normalized_for_post_analysis(def_id)
1122    }
1123
1124    /// Modify the `typing_mode` to `PostAnalysis` and eagerly reveal all
1125    /// opaque types in the `param_env`.
1126    pub fn with_post_analysis_normalized(self, tcx: TyCtxt<'tcx>) -> TypingEnv<'tcx> {
1127        let TypingEnv { typing_mode, param_env } = self;
1128        if let TypingMode::PostAnalysis = typing_mode {
1129            return self;
1130        }
1131
1132        // No need to reveal opaques with the new solver enabled,
1133        // since we have lazy norm.
1134        let param_env = if tcx.next_trait_solver_globally() {
1135            param_env
1136        } else {
1137            ParamEnv::new(tcx.reveal_opaque_types_in_bounds(param_env.caller_bounds()))
1138        };
1139        TypingEnv { typing_mode: TypingMode::PostAnalysis, param_env }
1140    }
1141
1142    /// Combine this typing environment with the given `value` to be used by
1143    /// not (yet) canonicalized queries. This only works if the value does not
1144    /// contain anything local to some `InferCtxt`, i.e. inference variables or
1145    /// placeholders.
1146    pub fn as_query_input<T>(self, value: T) -> PseudoCanonicalInput<'tcx, T>
1147    where
1148        T: TypeVisitable<TyCtxt<'tcx>>,
1149    {
1150        // FIXME(#132279): We should assert that the value does not contain any placeholders
1151        // as these placeholders are also local to the current inference context. However, we
1152        // currently use pseudo-canonical queries in the trait solver which replaces params with
1153        // placeholders. We should also simply not use pseudo-canonical queries in the trait
1154        // solver, at which point we can readd this assert. As of writing this comment, this is
1155        // only used by `fn layout_is_pointer_like` when calling `layout_of`.
1156        //
1157        // debug_assert!(!value.has_placeholders());
1158        PseudoCanonicalInput { typing_env: self, value }
1159    }
1160}
1161
1162/// Similar to `CanonicalInput`, this carries the `typing_mode` and the environment
1163/// necessary to do any kind of trait solving inside of nested queries.
1164///
1165/// Unlike proper canonicalization, this requires the `param_env` and the `value` to not
1166/// contain anything local to the `infcx` of the caller, so we don't actually canonicalize
1167/// anything.
1168///
1169/// This should be created by using `infcx.pseudo_canonicalize_query(param_env, value)`
1170/// or by using `typing_env.as_query_input(value)`.
1171#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
1172#[derive(HashStable, TypeVisitable, TypeFoldable)]
1173pub struct PseudoCanonicalInput<'tcx, T> {
1174    pub typing_env: TypingEnv<'tcx>,
1175    pub value: T,
1176}
1177
1178#[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
1179pub struct Destructor {
1180    /// The `DefId` of the destructor method
1181    pub did: DefId,
1182}
1183
1184// FIXME: consider combining this definition with regular `Destructor`
1185#[derive(Copy, Clone, Debug, HashStable, Encodable, Decodable)]
1186pub struct AsyncDestructor {
1187    /// The `DefId` of the `impl AsyncDrop`
1188    pub impl_did: DefId,
1189}
1190
1191#[derive(Clone, Copy, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
1192pub struct VariantFlags(u8);
1193bitflags::bitflags! {
1194    impl VariantFlags: u8 {
1195        const NO_VARIANT_FLAGS        = 0;
1196        /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1197        const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1198    }
1199}
1200rustc_data_structures::external_bitflags_debug! { VariantFlags }
1201
1202/// Definition of a variant -- a struct's fields or an enum variant.
1203#[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1204pub struct VariantDef {
1205    /// `DefId` that identifies the variant itself.
1206    /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1207    pub def_id: DefId,
1208    /// `DefId` that identifies the variant's constructor.
1209    /// If this variant is a struct variant, then this is `None`.
1210    pub ctor: Option<(CtorKind, DefId)>,
1211    /// Variant or struct name.
1212    pub name: Symbol,
1213    /// Discriminant of this variant.
1214    pub discr: VariantDiscr,
1215    /// Fields of this variant.
1216    pub fields: IndexVec<FieldIdx, FieldDef>,
1217    /// The error guarantees from parser, if any.
1218    tainted: Option<ErrorGuaranteed>,
1219    /// Flags of the variant (e.g. is field list non-exhaustive)?
1220    flags: VariantFlags,
1221}
1222
1223impl VariantDef {
1224    /// Creates a new `VariantDef`.
1225    ///
1226    /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1227    /// represents an enum variant).
1228    ///
1229    /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1230    /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1231    ///
1232    /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1233    /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1234    /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1235    /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1236    /// built-in trait), and we do not want to load attributes twice.
1237    ///
1238    /// If someone speeds up attribute loading to not be a performance concern, they can
1239    /// remove this hack and use the constructor `DefId` everywhere.
1240    #[instrument(level = "debug")]
1241    pub fn new(
1242        name: Symbol,
1243        variant_did: Option<DefId>,
1244        ctor: Option<(CtorKind, DefId)>,
1245        discr: VariantDiscr,
1246        fields: IndexVec<FieldIdx, FieldDef>,
1247        parent_did: DefId,
1248        recover_tainted: Option<ErrorGuaranteed>,
1249        is_field_list_non_exhaustive: bool,
1250    ) -> Self {
1251        let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1252        if is_field_list_non_exhaustive {
1253            flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1254        }
1255
1256        VariantDef {
1257            def_id: variant_did.unwrap_or(parent_did),
1258            ctor,
1259            name,
1260            discr,
1261            fields,
1262            flags,
1263            tainted: recover_tainted,
1264        }
1265    }
1266
1267    /// Returns `true` if the field list of this variant is `#[non_exhaustive]`.
1268    ///
1269    /// Note that this function will return `true` even if the type has been
1270    /// defined in the crate currently being compiled. If that's not what you
1271    /// want, see [`Self::field_list_has_applicable_non_exhaustive`].
1272    #[inline]
1273    pub fn is_field_list_non_exhaustive(&self) -> bool {
1274        self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1275    }
1276
1277    /// Returns `true` if the field list of this variant is `#[non_exhaustive]`
1278    /// and the type has been defined in another crate.
1279    #[inline]
1280    pub fn field_list_has_applicable_non_exhaustive(&self) -> bool {
1281        self.is_field_list_non_exhaustive() && !self.def_id.is_local()
1282    }
1283
1284    /// Computes the `Ident` of this variant by looking up the `Span`
1285    pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1286        Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1287    }
1288
1289    /// Was this variant obtained as part of recovering from a syntactic error?
1290    #[inline]
1291    pub fn has_errors(&self) -> Result<(), ErrorGuaranteed> {
1292        self.tainted.map_or(Ok(()), Err)
1293    }
1294
1295    #[inline]
1296    pub fn ctor_kind(&self) -> Option<CtorKind> {
1297        self.ctor.map(|(kind, _)| kind)
1298    }
1299
1300    #[inline]
1301    pub fn ctor_def_id(&self) -> Option<DefId> {
1302        self.ctor.map(|(_, def_id)| def_id)
1303    }
1304
1305    /// Returns the one field in this variant.
1306    ///
1307    /// `panic!`s if there are no fields or multiple fields.
1308    #[inline]
1309    pub fn single_field(&self) -> &FieldDef {
1310        assert!(self.fields.len() == 1);
1311
1312        &self.fields[FieldIdx::ZERO]
1313    }
1314
1315    /// Returns the last field in this variant, if present.
1316    #[inline]
1317    pub fn tail_opt(&self) -> Option<&FieldDef> {
1318        self.fields.raw.last()
1319    }
1320
1321    /// Returns the last field in this variant.
1322    ///
1323    /// # Panics
1324    ///
1325    /// Panics, if the variant has no fields.
1326    #[inline]
1327    pub fn tail(&self) -> &FieldDef {
1328        self.tail_opt().expect("expected unsized ADT to have a tail field")
1329    }
1330
1331    /// Returns whether this variant has unsafe fields.
1332    pub fn has_unsafe_fields(&self) -> bool {
1333        self.fields.iter().any(|x| x.safety.is_unsafe())
1334    }
1335}
1336
1337impl PartialEq for VariantDef {
1338    #[inline]
1339    fn eq(&self, other: &Self) -> bool {
1340        // There should be only one `VariantDef` for each `def_id`, therefore
1341        // it is fine to implement `PartialEq` only based on `def_id`.
1342        //
1343        // Below, we exhaustively destructure `self` and `other` so that if the
1344        // definition of `VariantDef` changes, a compile-error will be produced,
1345        // reminding us to revisit this assumption.
1346
1347        let Self {
1348            def_id: lhs_def_id,
1349            ctor: _,
1350            name: _,
1351            discr: _,
1352            fields: _,
1353            flags: _,
1354            tainted: _,
1355        } = &self;
1356        let Self {
1357            def_id: rhs_def_id,
1358            ctor: _,
1359            name: _,
1360            discr: _,
1361            fields: _,
1362            flags: _,
1363            tainted: _,
1364        } = other;
1365
1366        let res = lhs_def_id == rhs_def_id;
1367
1368        // Double check that implicit assumption detailed above.
1369        if cfg!(debug_assertions) && res {
1370            let deep = self.ctor == other.ctor
1371                && self.name == other.name
1372                && self.discr == other.discr
1373                && self.fields == other.fields
1374                && self.flags == other.flags;
1375            assert!(deep, "VariantDef for the same def-id has differing data");
1376        }
1377
1378        res
1379    }
1380}
1381
1382impl Eq for VariantDef {}
1383
1384impl Hash for VariantDef {
1385    #[inline]
1386    fn hash<H: Hasher>(&self, s: &mut H) {
1387        // There should be only one `VariantDef` for each `def_id`, therefore
1388        // it is fine to implement `Hash` only based on `def_id`.
1389        //
1390        // Below, we exhaustively destructure `self` so that if the definition
1391        // of `VariantDef` changes, a compile-error will be produced, reminding
1392        // us to revisit this assumption.
1393
1394        let Self { def_id, ctor: _, name: _, discr: _, fields: _, flags: _, tainted: _ } = &self;
1395        def_id.hash(s)
1396    }
1397}
1398
1399#[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1400pub enum VariantDiscr {
1401    /// Explicit value for this variant, i.e., `X = 123`.
1402    /// The `DefId` corresponds to the embedded constant.
1403    Explicit(DefId),
1404
1405    /// The previous variant's discriminant plus one.
1406    /// For efficiency reasons, the distance from the
1407    /// last `Explicit` discriminant is being stored,
1408    /// or `0` for the first variant, if it has none.
1409    Relative(u32),
1410}
1411
1412#[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1413pub struct FieldDef {
1414    pub did: DefId,
1415    pub name: Symbol,
1416    pub vis: Visibility<DefId>,
1417    pub safety: hir::Safety,
1418    pub value: Option<DefId>,
1419}
1420
1421impl PartialEq for FieldDef {
1422    #[inline]
1423    fn eq(&self, other: &Self) -> bool {
1424        // There should be only one `FieldDef` for each `did`, therefore it is
1425        // fine to implement `PartialEq` only based on `did`.
1426        //
1427        // Below, we exhaustively destructure `self` so that if the definition
1428        // of `FieldDef` changes, a compile-error will be produced, reminding
1429        // us to revisit this assumption.
1430
1431        let Self { did: lhs_did, name: _, vis: _, safety: _, value: _ } = &self;
1432
1433        let Self { did: rhs_did, name: _, vis: _, safety: _, value: _ } = other;
1434
1435        let res = lhs_did == rhs_did;
1436
1437        // Double check that implicit assumption detailed above.
1438        if cfg!(debug_assertions) && res {
1439            let deep =
1440                self.name == other.name && self.vis == other.vis && self.safety == other.safety;
1441            assert!(deep, "FieldDef for the same def-id has differing data");
1442        }
1443
1444        res
1445    }
1446}
1447
1448impl Eq for FieldDef {}
1449
1450impl Hash for FieldDef {
1451    #[inline]
1452    fn hash<H: Hasher>(&self, s: &mut H) {
1453        // There should be only one `FieldDef` for each `did`, therefore it is
1454        // fine to implement `Hash` only based on `did`.
1455        //
1456        // Below, we exhaustively destructure `self` so that if the definition
1457        // of `FieldDef` changes, a compile-error will be produced, reminding
1458        // us to revisit this assumption.
1459
1460        let Self { did, name: _, vis: _, safety: _, value: _ } = &self;
1461
1462        did.hash(s)
1463    }
1464}
1465
1466impl<'tcx> FieldDef {
1467    /// Returns the type of this field. The resulting type is not normalized. The `arg` is
1468    /// typically obtained via the second field of [`TyKind::Adt`].
1469    pub fn ty(&self, tcx: TyCtxt<'tcx>, args: GenericArgsRef<'tcx>) -> Ty<'tcx> {
1470        tcx.type_of(self.did).instantiate(tcx, args)
1471    }
1472
1473    /// Computes the `Ident` of this variant by looking up the `Span`
1474    pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1475        Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
1476    }
1477}
1478
1479#[derive(Debug, PartialEq, Eq)]
1480pub enum ImplOverlapKind {
1481    /// These impls are always allowed to overlap.
1482    Permitted {
1483        /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1484        marker: bool,
1485    },
1486}
1487
1488/// Useful source information about where a desugared associated type for an
1489/// RPITIT originated from.
1490#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Encodable, Decodable, HashStable)]
1491pub enum ImplTraitInTraitData {
1492    Trait { fn_def_id: DefId, opaque_def_id: DefId },
1493    Impl { fn_def_id: DefId },
1494}
1495
1496impl<'tcx> TyCtxt<'tcx> {
1497    pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1498        self.typeck(self.hir_body_owner_def_id(body))
1499    }
1500
1501    pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1502        self.associated_items(id)
1503            .in_definition_order()
1504            .filter(move |item| item.is_fn() && item.defaultness(self).has_value())
1505    }
1506
1507    pub fn repr_options_of_def(self, did: LocalDefId) -> ReprOptions {
1508        let mut flags = ReprFlags::empty();
1509        let mut size = None;
1510        let mut max_align: Option<Align> = None;
1511        let mut min_pack: Option<Align> = None;
1512
1513        // Generate a deterministically-derived seed from the item's path hash
1514        // to allow for cross-crate compilation to actually work
1515        let mut field_shuffle_seed = self.def_path_hash(did.to_def_id()).0.to_smaller_hash();
1516
1517        // If the user defined a custom seed for layout randomization, xor the item's
1518        // path hash with the user defined seed, this will allowing determinism while
1519        // still allowing users to further randomize layout generation for e.g. fuzzing
1520        if let Some(user_seed) = self.sess.opts.unstable_opts.layout_seed {
1521            field_shuffle_seed ^= user_seed;
1522        }
1523
1524        if let Some(reprs) = attr::find_attr!(self.get_all_attrs(did), AttributeKind::Repr(r) => r)
1525        {
1526            for (r, _) in reprs {
1527                flags.insert(match *r {
1528                    attr::ReprRust => ReprFlags::empty(),
1529                    attr::ReprC => ReprFlags::IS_C,
1530                    attr::ReprPacked(pack) => {
1531                        min_pack = Some(if let Some(min_pack) = min_pack {
1532                            min_pack.min(pack)
1533                        } else {
1534                            pack
1535                        });
1536                        ReprFlags::empty()
1537                    }
1538                    attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1539                    attr::ReprSimd => ReprFlags::IS_SIMD,
1540                    attr::ReprInt(i) => {
1541                        size = Some(match i {
1542                            attr::IntType::SignedInt(x) => match x {
1543                                ast::IntTy::Isize => IntegerType::Pointer(true),
1544                                ast::IntTy::I8 => IntegerType::Fixed(Integer::I8, true),
1545                                ast::IntTy::I16 => IntegerType::Fixed(Integer::I16, true),
1546                                ast::IntTy::I32 => IntegerType::Fixed(Integer::I32, true),
1547                                ast::IntTy::I64 => IntegerType::Fixed(Integer::I64, true),
1548                                ast::IntTy::I128 => IntegerType::Fixed(Integer::I128, true),
1549                            },
1550                            attr::IntType::UnsignedInt(x) => match x {
1551                                ast::UintTy::Usize => IntegerType::Pointer(false),
1552                                ast::UintTy::U8 => IntegerType::Fixed(Integer::I8, false),
1553                                ast::UintTy::U16 => IntegerType::Fixed(Integer::I16, false),
1554                                ast::UintTy::U32 => IntegerType::Fixed(Integer::I32, false),
1555                                ast::UintTy::U64 => IntegerType::Fixed(Integer::I64, false),
1556                                ast::UintTy::U128 => IntegerType::Fixed(Integer::I128, false),
1557                            },
1558                        });
1559                        ReprFlags::empty()
1560                    }
1561                    attr::ReprAlign(align) => {
1562                        max_align = max_align.max(Some(align));
1563                        ReprFlags::empty()
1564                    }
1565                    attr::ReprEmpty => {
1566                        /* skip these, they're just for diagnostics */
1567                        ReprFlags::empty()
1568                    }
1569                });
1570            }
1571        }
1572
1573        // If `-Z randomize-layout` was enabled for the type definition then we can
1574        // consider performing layout randomization
1575        if self.sess.opts.unstable_opts.randomize_layout {
1576            flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1577        }
1578
1579        // box is special, on the one hand the compiler assumes an ordered layout, with the pointer
1580        // always at offset zero. On the other hand we want scalar abi optimizations.
1581        let is_box = self.is_lang_item(did.to_def_id(), LangItem::OwnedBox);
1582
1583        // This is here instead of layout because the choice must make it into metadata.
1584        if is_box {
1585            flags.insert(ReprFlags::IS_LINEAR);
1586        }
1587
1588        ReprOptions { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1589    }
1590
1591    /// Look up the name of a definition across crates. This does not look at HIR.
1592    pub fn opt_item_name(self, def_id: DefId) -> Option<Symbol> {
1593        if let Some(cnum) = def_id.as_crate_root() {
1594            Some(self.crate_name(cnum))
1595        } else {
1596            let def_key = self.def_key(def_id);
1597            match def_key.disambiguated_data.data {
1598                // The name of a constructor is that of its parent.
1599                rustc_hir::definitions::DefPathData::Ctor => self
1600                    .opt_item_name(DefId { krate: def_id.krate, index: def_key.parent.unwrap() }),
1601                _ => def_key.get_opt_name(),
1602            }
1603        }
1604    }
1605
1606    /// Look up the name of a definition across crates. This does not look at HIR.
1607    ///
1608    /// This method will ICE if the corresponding item does not have a name. In these cases, use
1609    /// [`opt_item_name`] instead.
1610    ///
1611    /// [`opt_item_name`]: Self::opt_item_name
1612    pub fn item_name(self, id: DefId) -> Symbol {
1613        self.opt_item_name(id).unwrap_or_else(|| {
1614            bug!("item_name: no name for {:?}", self.def_path(id));
1615        })
1616    }
1617
1618    /// Look up the name and span of a definition.
1619    ///
1620    /// See [`item_name`][Self::item_name] for more information.
1621    pub fn opt_item_ident(self, def_id: DefId) -> Option<Ident> {
1622        let def = self.opt_item_name(def_id)?;
1623        let span = self
1624            .def_ident_span(def_id)
1625            .unwrap_or_else(|| bug!("missing ident span for {def_id:?}"));
1626        Some(Ident::new(def, span))
1627    }
1628
1629    /// Look up the name and span of a definition.
1630    ///
1631    /// See [`item_name`][Self::item_name] for more information.
1632    pub fn item_ident(self, def_id: DefId) -> Ident {
1633        self.opt_item_ident(def_id).unwrap_or_else(|| {
1634            bug!("item_ident: no name for {:?}", self.def_path(def_id));
1635        })
1636    }
1637
1638    pub fn opt_associated_item(self, def_id: DefId) -> Option<AssocItem> {
1639        if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
1640            Some(self.associated_item(def_id))
1641        } else {
1642            None
1643        }
1644    }
1645
1646    /// If the `def_id` is an associated type that was desugared from a
1647    /// return-position `impl Trait` from a trait, then provide the source info
1648    /// about where that RPITIT came from.
1649    pub fn opt_rpitit_info(self, def_id: DefId) -> Option<ImplTraitInTraitData> {
1650        if let DefKind::AssocTy = self.def_kind(def_id)
1651            && let AssocKind::Type { data: AssocTypeData::Rpitit(rpitit_info) } =
1652                self.associated_item(def_id).kind
1653        {
1654            Some(rpitit_info)
1655        } else {
1656            None
1657        }
1658    }
1659
1660    pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<FieldIdx> {
1661        variant.fields.iter_enumerated().find_map(|(i, field)| {
1662            self.hygienic_eq(ident, field.ident(self), variant.def_id).then_some(i)
1663        })
1664    }
1665
1666    /// Returns `Some` if the impls are the same polarity and the trait either
1667    /// has no items or is annotated `#[marker]` and prevents item overrides.
1668    #[instrument(level = "debug", skip(self), ret)]
1669    pub fn impls_are_allowed_to_overlap(
1670        self,
1671        def_id1: DefId,
1672        def_id2: DefId,
1673    ) -> Option<ImplOverlapKind> {
1674        let impl1 = self.impl_trait_header(def_id1).unwrap();
1675        let impl2 = self.impl_trait_header(def_id2).unwrap();
1676
1677        let trait_ref1 = impl1.trait_ref.skip_binder();
1678        let trait_ref2 = impl2.trait_ref.skip_binder();
1679
1680        // If either trait impl references an error, they're allowed to overlap,
1681        // as one of them essentially doesn't exist.
1682        if trait_ref1.references_error() || trait_ref2.references_error() {
1683            return Some(ImplOverlapKind::Permitted { marker: false });
1684        }
1685
1686        match (impl1.polarity, impl2.polarity) {
1687            (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
1688                // `#[rustc_reservation_impl]` impls don't overlap with anything
1689                return Some(ImplOverlapKind::Permitted { marker: false });
1690            }
1691            (ImplPolarity::Positive, ImplPolarity::Negative)
1692            | (ImplPolarity::Negative, ImplPolarity::Positive) => {
1693                // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
1694                return None;
1695            }
1696            (ImplPolarity::Positive, ImplPolarity::Positive)
1697            | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
1698        };
1699
1700        let is_marker_impl = |trait_ref: TraitRef<'_>| self.trait_def(trait_ref.def_id).is_marker;
1701        let is_marker_overlap = is_marker_impl(trait_ref1) && is_marker_impl(trait_ref2);
1702
1703        if is_marker_overlap {
1704            return Some(ImplOverlapKind::Permitted { marker: true });
1705        }
1706
1707        None
1708    }
1709
1710    /// Returns `ty::VariantDef` if `res` refers to a struct,
1711    /// or variant or their constructors, panics otherwise.
1712    pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
1713        match res {
1714            Res::Def(DefKind::Variant, did) => {
1715                let enum_did = self.parent(did);
1716                self.adt_def(enum_did).variant_with_id(did)
1717            }
1718            Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
1719            Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
1720                let variant_did = self.parent(variant_ctor_did);
1721                let enum_did = self.parent(variant_did);
1722                self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
1723            }
1724            Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
1725                let struct_did = self.parent(ctor_did);
1726                self.adt_def(struct_did).non_enum_variant()
1727            }
1728            _ => bug!("expect_variant_res used with unexpected res {:?}", res),
1729        }
1730    }
1731
1732    /// Returns the possibly-auto-generated MIR of a [`ty::InstanceKind`].
1733    #[instrument(skip(self), level = "debug")]
1734    pub fn instance_mir(self, instance: ty::InstanceKind<'tcx>) -> &'tcx Body<'tcx> {
1735        match instance {
1736            ty::InstanceKind::Item(def) => {
1737                debug!("calling def_kind on def: {:?}", def);
1738                let def_kind = self.def_kind(def);
1739                debug!("returned from def_kind: {:?}", def_kind);
1740                match def_kind {
1741                    DefKind::Const
1742                    | DefKind::Static { .. }
1743                    | DefKind::AssocConst
1744                    | DefKind::Ctor(..)
1745                    | DefKind::AnonConst
1746                    | DefKind::InlineConst => self.mir_for_ctfe(def),
1747                    // If the caller wants `mir_for_ctfe` of a function they should not be using
1748                    // `instance_mir`, so we'll assume const fn also wants the optimized version.
1749                    _ => self.optimized_mir(def),
1750                }
1751            }
1752            ty::InstanceKind::VTableShim(..)
1753            | ty::InstanceKind::ReifyShim(..)
1754            | ty::InstanceKind::Intrinsic(..)
1755            | ty::InstanceKind::FnPtrShim(..)
1756            | ty::InstanceKind::Virtual(..)
1757            | ty::InstanceKind::ClosureOnceShim { .. }
1758            | ty::InstanceKind::ConstructCoroutineInClosureShim { .. }
1759            | ty::InstanceKind::FutureDropPollShim(..)
1760            | ty::InstanceKind::DropGlue(..)
1761            | ty::InstanceKind::CloneShim(..)
1762            | ty::InstanceKind::ThreadLocalShim(..)
1763            | ty::InstanceKind::FnPtrAddrShim(..)
1764            | ty::InstanceKind::AsyncDropGlueCtorShim(..)
1765            | ty::InstanceKind::AsyncDropGlue(..) => self.mir_shims(instance),
1766        }
1767    }
1768
1769    // FIXME(@lcnr): Remove this function.
1770    pub fn get_attrs_unchecked(self, did: DefId) -> &'tcx [hir::Attribute] {
1771        if let Some(did) = did.as_local() {
1772            self.hir_attrs(self.local_def_id_to_hir_id(did))
1773        } else {
1774            self.attrs_for_def(did)
1775        }
1776    }
1777
1778    /// Gets all attributes with the given name.
1779    pub fn get_attrs(
1780        self,
1781        did: impl Into<DefId>,
1782        attr: Symbol,
1783    ) -> impl Iterator<Item = &'tcx hir::Attribute> {
1784        self.get_all_attrs(did).filter(move |a: &&hir::Attribute| a.has_name(attr))
1785    }
1786
1787    /// Gets all attributes.
1788    ///
1789    /// To see if an item has a specific attribute, you should use [`rustc_attr_data_structures::find_attr!`] so you can use matching.
1790    pub fn get_all_attrs(
1791        self,
1792        did: impl Into<DefId>,
1793    ) -> impl Iterator<Item = &'tcx hir::Attribute> {
1794        let did: DefId = did.into();
1795        if let Some(did) = did.as_local() {
1796            self.hir_attrs(self.local_def_id_to_hir_id(did)).iter()
1797        } else {
1798            self.attrs_for_def(did).iter()
1799        }
1800    }
1801
1802    /// Get an attribute from the diagnostic attribute namespace
1803    ///
1804    /// This function requests an attribute with the following structure:
1805    ///
1806    /// `#[diagnostic::$attr]`
1807    ///
1808    /// This function performs feature checking, so if an attribute is returned
1809    /// it can be used by the consumer
1810    pub fn get_diagnostic_attr(
1811        self,
1812        did: impl Into<DefId>,
1813        attr: Symbol,
1814    ) -> Option<&'tcx hir::Attribute> {
1815        let did: DefId = did.into();
1816        if did.as_local().is_some() {
1817            // it's a crate local item, we need to check feature flags
1818            if rustc_feature::is_stable_diagnostic_attribute(attr, self.features()) {
1819                self.get_attrs_by_path(did, &[sym::diagnostic, sym::do_not_recommend]).next()
1820            } else {
1821                None
1822            }
1823        } else {
1824            // we filter out unstable diagnostic attributes before
1825            // encoding attributes
1826            debug_assert!(rustc_feature::encode_cross_crate(attr));
1827            self.attrs_for_def(did)
1828                .iter()
1829                .find(|a| matches!(a.path().as_ref(), [sym::diagnostic, a] if *a == attr))
1830        }
1831    }
1832
1833    pub fn get_attrs_by_path(
1834        self,
1835        did: DefId,
1836        attr: &[Symbol],
1837    ) -> impl Iterator<Item = &'tcx hir::Attribute> {
1838        let filter_fn = move |a: &&hir::Attribute| a.path_matches(attr);
1839        if let Some(did) = did.as_local() {
1840            self.hir_attrs(self.local_def_id_to_hir_id(did)).iter().filter(filter_fn)
1841        } else {
1842            self.attrs_for_def(did).iter().filter(filter_fn)
1843        }
1844    }
1845
1846    pub fn get_attr(self, did: impl Into<DefId>, attr: Symbol) -> Option<&'tcx hir::Attribute> {
1847        if cfg!(debug_assertions) && !rustc_feature::is_valid_for_get_attr(attr) {
1848            let did: DefId = did.into();
1849            bug!("get_attr: unexpected called with DefId `{:?}`, attr `{:?}`", did, attr);
1850        } else {
1851            self.get_attrs(did, attr).next()
1852        }
1853    }
1854
1855    /// Determines whether an item is annotated with an attribute.
1856    pub fn has_attr(self, did: impl Into<DefId>, attr: Symbol) -> bool {
1857        self.get_attrs(did, attr).next().is_some()
1858    }
1859
1860    /// Determines whether an item is annotated with a multi-segment attribute
1861    pub fn has_attrs_with_path(self, did: impl Into<DefId>, attrs: &[Symbol]) -> bool {
1862        self.get_attrs_by_path(did.into(), attrs).next().is_some()
1863    }
1864
1865    /// Returns `true` if this is an `auto trait`.
1866    pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
1867        self.trait_def(trait_def_id).has_auto_impl
1868    }
1869
1870    /// Returns `true` if this is coinductive, either because it is
1871    /// an auto trait or because it has the `#[rustc_coinductive]` attribute.
1872    pub fn trait_is_coinductive(self, trait_def_id: DefId) -> bool {
1873        self.trait_def(trait_def_id).is_coinductive
1874    }
1875
1876    /// Returns `true` if this is a trait alias.
1877    pub fn trait_is_alias(self, trait_def_id: DefId) -> bool {
1878        self.def_kind(trait_def_id) == DefKind::TraitAlias
1879    }
1880
1881    /// Arena-alloc of LayoutError for coroutine layout
1882    fn layout_error(self, err: LayoutError<'tcx>) -> &'tcx LayoutError<'tcx> {
1883        self.arena.alloc(err)
1884    }
1885
1886    /// Returns layout of a non-async-drop coroutine. Layout might be unavailable if the
1887    /// coroutine is tainted by errors.
1888    ///
1889    /// Takes `coroutine_kind` which can be acquired from the `CoroutineArgs::kind_ty`,
1890    /// e.g. `args.as_coroutine().kind_ty()`.
1891    fn ordinary_coroutine_layout(
1892        self,
1893        def_id: DefId,
1894        args: GenericArgsRef<'tcx>,
1895    ) -> Result<&'tcx CoroutineLayout<'tcx>, &'tcx LayoutError<'tcx>> {
1896        let coroutine_kind_ty = args.as_coroutine().kind_ty();
1897        let mir = self.optimized_mir(def_id);
1898        let ty = || Ty::new_coroutine(self, def_id, args);
1899        // Regular coroutine
1900        if coroutine_kind_ty.is_unit() {
1901            mir.coroutine_layout_raw().ok_or_else(|| self.layout_error(LayoutError::Unknown(ty())))
1902        } else {
1903            // If we have a `Coroutine` that comes from an coroutine-closure,
1904            // then it may be a by-move or by-ref body.
1905            let ty::Coroutine(_, identity_args) =
1906                *self.type_of(def_id).instantiate_identity().kind()
1907            else {
1908                unreachable!();
1909            };
1910            let identity_kind_ty = identity_args.as_coroutine().kind_ty();
1911            // If the types differ, then we must be getting the by-move body of
1912            // a by-ref coroutine.
1913            if identity_kind_ty == coroutine_kind_ty {
1914                mir.coroutine_layout_raw()
1915                    .ok_or_else(|| self.layout_error(LayoutError::Unknown(ty())))
1916            } else {
1917                assert_matches!(coroutine_kind_ty.to_opt_closure_kind(), Some(ClosureKind::FnOnce));
1918                assert_matches!(
1919                    identity_kind_ty.to_opt_closure_kind(),
1920                    Some(ClosureKind::Fn | ClosureKind::FnMut)
1921                );
1922                self.optimized_mir(self.coroutine_by_move_body_def_id(def_id))
1923                    .coroutine_layout_raw()
1924                    .ok_or_else(|| self.layout_error(LayoutError::Unknown(ty())))
1925            }
1926        }
1927    }
1928
1929    /// Returns layout of a `async_drop_in_place::{closure}` coroutine
1930    ///   (returned from `async fn async_drop_in_place<T>(..)`).
1931    /// Layout might be unavailable if the coroutine is tainted by errors.
1932    fn async_drop_coroutine_layout(
1933        self,
1934        def_id: DefId,
1935        args: GenericArgsRef<'tcx>,
1936    ) -> Result<&'tcx CoroutineLayout<'tcx>, &'tcx LayoutError<'tcx>> {
1937        let ty = || Ty::new_coroutine(self, def_id, args);
1938        if args[0].has_placeholders() || args[0].has_non_region_param() {
1939            return Err(self.layout_error(LayoutError::TooGeneric(ty())));
1940        }
1941        let instance = InstanceKind::AsyncDropGlue(def_id, Ty::new_coroutine(self, def_id, args));
1942        self.mir_shims(instance)
1943            .coroutine_layout_raw()
1944            .ok_or_else(|| self.layout_error(LayoutError::Unknown(ty())))
1945    }
1946
1947    /// Returns layout of a coroutine. Layout might be unavailable if the
1948    /// coroutine is tainted by errors.
1949    pub fn coroutine_layout(
1950        self,
1951        def_id: DefId,
1952        args: GenericArgsRef<'tcx>,
1953    ) -> Result<&'tcx CoroutineLayout<'tcx>, &'tcx LayoutError<'tcx>> {
1954        if self.is_async_drop_in_place_coroutine(def_id) {
1955            // layout of `async_drop_in_place<T>::{closure}` in case,
1956            // when T is a coroutine, contains this internal coroutine's ptr in upvars
1957            // and doesn't require any locals. Here is an `empty coroutine's layout`
1958            let arg_cor_ty = args.first().unwrap().expect_ty();
1959            if arg_cor_ty.is_coroutine() {
1960                let span = self.def_span(def_id);
1961                let source_info = SourceInfo::outermost(span);
1962                // Even minimal, empty coroutine has 3 states (RESERVED_VARIANTS),
1963                // so variant_fields and variant_source_info should have 3 elements.
1964                let variant_fields: IndexVec<VariantIdx, IndexVec<FieldIdx, CoroutineSavedLocal>> =
1965                    iter::repeat(IndexVec::new()).take(CoroutineArgs::RESERVED_VARIANTS).collect();
1966                let variant_source_info: IndexVec<VariantIdx, SourceInfo> =
1967                    iter::repeat(source_info).take(CoroutineArgs::RESERVED_VARIANTS).collect();
1968                let proxy_layout = CoroutineLayout {
1969                    field_tys: [].into(),
1970                    field_names: [].into(),
1971                    variant_fields,
1972                    variant_source_info,
1973                    storage_conflicts: BitMatrix::new(0, 0),
1974                };
1975                return Ok(self.arena.alloc(proxy_layout));
1976            } else {
1977                self.async_drop_coroutine_layout(def_id, args)
1978            }
1979        } else {
1980            self.ordinary_coroutine_layout(def_id, args)
1981        }
1982    }
1983
1984    /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
1985    /// If it implements no trait, returns `None`.
1986    pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
1987        self.impl_trait_ref(def_id).map(|tr| tr.skip_binder().def_id)
1988    }
1989
1990    /// If the given `DefId` describes an item belonging to a trait,
1991    /// returns the `DefId` of the trait that the trait item belongs to;
1992    /// otherwise, returns `None`.
1993    pub fn trait_of_item(self, def_id: DefId) -> Option<DefId> {
1994        if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
1995            let parent = self.parent(def_id);
1996            if let DefKind::Trait | DefKind::TraitAlias = self.def_kind(parent) {
1997                return Some(parent);
1998            }
1999        }
2000        None
2001    }
2002
2003    /// If the given `DefId` describes a method belonging to an impl, returns the
2004    /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2005    pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2006        if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
2007            let parent = self.parent(def_id);
2008            if let DefKind::Impl { .. } = self.def_kind(parent) {
2009                return Some(parent);
2010            }
2011        }
2012        None
2013    }
2014
2015    pub fn is_exportable(self, def_id: DefId) -> bool {
2016        self.exportable_items(def_id.krate).contains(&def_id)
2017    }
2018
2019    /// Check if the given `DefId` is `#\[automatically_derived\]`, *and*
2020    /// whether it was produced by expanding a builtin derive macro.
2021    pub fn is_builtin_derived(self, def_id: DefId) -> bool {
2022        if self.is_automatically_derived(def_id)
2023            && let Some(def_id) = def_id.as_local()
2024            && let outer = self.def_span(def_id).ctxt().outer_expn_data()
2025            && matches!(outer.kind, ExpnKind::Macro(MacroKind::Derive, _))
2026            && self.has_attr(outer.macro_def_id.unwrap(), sym::rustc_builtin_macro)
2027        {
2028            true
2029        } else {
2030            false
2031        }
2032    }
2033
2034    /// Check if the given `DefId` is `#\[automatically_derived\]`.
2035    pub fn is_automatically_derived(self, def_id: DefId) -> bool {
2036        self.has_attr(def_id, sym::automatically_derived)
2037    }
2038
2039    /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2040    /// with the name of the crate containing the impl.
2041    pub fn span_of_impl(self, impl_def_id: DefId) -> Result<Span, Symbol> {
2042        if let Some(impl_def_id) = impl_def_id.as_local() {
2043            Ok(self.def_span(impl_def_id))
2044        } else {
2045            Err(self.crate_name(impl_def_id.krate))
2046        }
2047    }
2048
2049    /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2050    /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2051    /// definition's parent/scope to perform comparison.
2052    pub fn hygienic_eq(self, use_ident: Ident, def_ident: Ident, def_parent_def_id: DefId) -> bool {
2053        // We could use `Ident::eq` here, but we deliberately don't. The identifier
2054        // comparison fails frequently, and we want to avoid the expensive
2055        // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2056        use_ident.name == def_ident.name
2057            && use_ident
2058                .span
2059                .ctxt()
2060                .hygienic_eq(def_ident.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2061    }
2062
2063    pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2064        ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2065        ident
2066    }
2067
2068    // FIXME(vincenzopalazzo): move the HirId to a LocalDefId
2069    pub fn adjust_ident_and_get_scope(
2070        self,
2071        mut ident: Ident,
2072        scope: DefId,
2073        block: hir::HirId,
2074    ) -> (Ident, DefId) {
2075        let scope = ident
2076            .span
2077            .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2078            .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2079            .unwrap_or_else(|| self.parent_module(block).to_def_id());
2080        (ident, scope)
2081    }
2082
2083    /// Checks whether this is a `const fn`. Returns `false` for non-functions.
2084    ///
2085    /// Even if this returns `true`, constness may still be unstable!
2086    #[inline]
2087    pub fn is_const_fn(self, def_id: DefId) -> bool {
2088        matches!(
2089            self.def_kind(def_id),
2090            DefKind::Fn | DefKind::AssocFn | DefKind::Ctor(_, CtorKind::Fn) | DefKind::Closure
2091        ) && self.constness(def_id) == hir::Constness::Const
2092    }
2093
2094    /// Whether this item is conditionally constant for the purposes of the
2095    /// effects implementation.
2096    ///
2097    /// This roughly corresponds to all const functions and other callable
2098    /// items, along with const impls and traits, and associated types within
2099    /// those impls and traits.
2100    pub fn is_conditionally_const(self, def_id: impl Into<DefId>) -> bool {
2101        let def_id: DefId = def_id.into();
2102        match self.def_kind(def_id) {
2103            DefKind::Impl { of_trait: true } => {
2104                let header = self.impl_trait_header(def_id).unwrap();
2105                header.constness == hir::Constness::Const
2106                    && self.is_const_trait(header.trait_ref.skip_binder().def_id)
2107            }
2108            DefKind::Fn | DefKind::Ctor(_, CtorKind::Fn) => {
2109                self.constness(def_id) == hir::Constness::Const
2110            }
2111            DefKind::Trait => self.is_const_trait(def_id),
2112            DefKind::AssocTy => {
2113                let parent_def_id = self.parent(def_id);
2114                match self.def_kind(parent_def_id) {
2115                    DefKind::Impl { of_trait: false } => false,
2116                    DefKind::Impl { of_trait: true } | DefKind::Trait => {
2117                        self.is_conditionally_const(parent_def_id)
2118                    }
2119                    _ => bug!("unexpected parent item of associated type: {parent_def_id:?}"),
2120                }
2121            }
2122            DefKind::AssocFn => {
2123                let parent_def_id = self.parent(def_id);
2124                match self.def_kind(parent_def_id) {
2125                    DefKind::Impl { of_trait: false } => {
2126                        self.constness(def_id) == hir::Constness::Const
2127                    }
2128                    DefKind::Impl { of_trait: true } | DefKind::Trait => {
2129                        self.is_conditionally_const(parent_def_id)
2130                    }
2131                    _ => bug!("unexpected parent item of associated fn: {parent_def_id:?}"),
2132                }
2133            }
2134            DefKind::OpaqueTy => match self.opaque_ty_origin(def_id) {
2135                hir::OpaqueTyOrigin::FnReturn { parent, .. } => self.is_conditionally_const(parent),
2136                hir::OpaqueTyOrigin::AsyncFn { .. } => false,
2137                // FIXME(const_trait_impl): ATPITs could be conditionally const?
2138                hir::OpaqueTyOrigin::TyAlias { .. } => false,
2139            },
2140            DefKind::Closure => {
2141                // Closures and RPITs will eventually have const conditions
2142                // for `[const]` bounds.
2143                false
2144            }
2145            DefKind::Ctor(_, CtorKind::Const)
2146            | DefKind::Impl { of_trait: false }
2147            | DefKind::Mod
2148            | DefKind::Struct
2149            | DefKind::Union
2150            | DefKind::Enum
2151            | DefKind::Variant
2152            | DefKind::TyAlias
2153            | DefKind::ForeignTy
2154            | DefKind::TraitAlias
2155            | DefKind::TyParam
2156            | DefKind::Const
2157            | DefKind::ConstParam
2158            | DefKind::Static { .. }
2159            | DefKind::AssocConst
2160            | DefKind::Macro(_)
2161            | DefKind::ExternCrate
2162            | DefKind::Use
2163            | DefKind::ForeignMod
2164            | DefKind::AnonConst
2165            | DefKind::InlineConst
2166            | DefKind::Field
2167            | DefKind::LifetimeParam
2168            | DefKind::GlobalAsm
2169            | DefKind::SyntheticCoroutineBody => false,
2170        }
2171    }
2172
2173    #[inline]
2174    pub fn is_const_trait(self, def_id: DefId) -> bool {
2175        self.trait_def(def_id).constness == hir::Constness::Const
2176    }
2177
2178    #[inline]
2179    pub fn is_const_default_method(self, def_id: DefId) -> bool {
2180        matches!(self.trait_of_item(def_id), Some(trait_id) if self.is_const_trait(trait_id))
2181    }
2182
2183    pub fn impl_method_has_trait_impl_trait_tys(self, def_id: DefId) -> bool {
2184        if self.def_kind(def_id) != DefKind::AssocFn {
2185            return false;
2186        }
2187
2188        let Some(item) = self.opt_associated_item(def_id) else {
2189            return false;
2190        };
2191        if item.container != ty::AssocItemContainer::Impl {
2192            return false;
2193        }
2194
2195        let Some(trait_item_def_id) = item.trait_item_def_id else {
2196            return false;
2197        };
2198
2199        return !self
2200            .associated_types_for_impl_traits_in_associated_fn(trait_item_def_id)
2201            .is_empty();
2202    }
2203}
2204
2205pub fn int_ty(ity: ast::IntTy) -> IntTy {
2206    match ity {
2207        ast::IntTy::Isize => IntTy::Isize,
2208        ast::IntTy::I8 => IntTy::I8,
2209        ast::IntTy::I16 => IntTy::I16,
2210        ast::IntTy::I32 => IntTy::I32,
2211        ast::IntTy::I64 => IntTy::I64,
2212        ast::IntTy::I128 => IntTy::I128,
2213    }
2214}
2215
2216pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2217    match uty {
2218        ast::UintTy::Usize => UintTy::Usize,
2219        ast::UintTy::U8 => UintTy::U8,
2220        ast::UintTy::U16 => UintTy::U16,
2221        ast::UintTy::U32 => UintTy::U32,
2222        ast::UintTy::U64 => UintTy::U64,
2223        ast::UintTy::U128 => UintTy::U128,
2224    }
2225}
2226
2227pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2228    match fty {
2229        ast::FloatTy::F16 => FloatTy::F16,
2230        ast::FloatTy::F32 => FloatTy::F32,
2231        ast::FloatTy::F64 => FloatTy::F64,
2232        ast::FloatTy::F128 => FloatTy::F128,
2233    }
2234}
2235
2236pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2237    match ity {
2238        IntTy::Isize => ast::IntTy::Isize,
2239        IntTy::I8 => ast::IntTy::I8,
2240        IntTy::I16 => ast::IntTy::I16,
2241        IntTy::I32 => ast::IntTy::I32,
2242        IntTy::I64 => ast::IntTy::I64,
2243        IntTy::I128 => ast::IntTy::I128,
2244    }
2245}
2246
2247pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2248    match uty {
2249        UintTy::Usize => ast::UintTy::Usize,
2250        UintTy::U8 => ast::UintTy::U8,
2251        UintTy::U16 => ast::UintTy::U16,
2252        UintTy::U32 => ast::UintTy::U32,
2253        UintTy::U64 => ast::UintTy::U64,
2254        UintTy::U128 => ast::UintTy::U128,
2255    }
2256}
2257
2258pub fn provide(providers: &mut Providers) {
2259    closure::provide(providers);
2260    context::provide(providers);
2261    erase_regions::provide(providers);
2262    inhabitedness::provide(providers);
2263    util::provide(providers);
2264    print::provide(providers);
2265    super::util::bug::provide(providers);
2266    *providers = Providers {
2267        trait_impls_of: trait_def::trait_impls_of_provider,
2268        incoherent_impls: trait_def::incoherent_impls_provider,
2269        trait_impls_in_crate: trait_def::trait_impls_in_crate_provider,
2270        traits: trait_def::traits_provider,
2271        vtable_allocation: vtable::vtable_allocation_provider,
2272        ..*providers
2273    };
2274}
2275
2276/// A map for the local crate mapping each type to a vector of its
2277/// inherent impls. This is not meant to be used outside of coherence;
2278/// rather, you should request the vector for a specific type via
2279/// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2280/// (constructing this map requires touching the entire crate).
2281#[derive(Clone, Debug, Default, HashStable)]
2282pub struct CrateInherentImpls {
2283    pub inherent_impls: FxIndexMap<LocalDefId, Vec<DefId>>,
2284    pub incoherent_impls: FxIndexMap<SimplifiedType, Vec<LocalDefId>>,
2285}
2286
2287#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2288pub struct SymbolName<'tcx> {
2289    /// `&str` gives a consistent ordering, which ensures reproducible builds.
2290    pub name: &'tcx str,
2291}
2292
2293impl<'tcx> SymbolName<'tcx> {
2294    pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2295        SymbolName { name: tcx.arena.alloc_str(name) }
2296    }
2297}
2298
2299impl<'tcx> fmt::Display for SymbolName<'tcx> {
2300    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2301        fmt::Display::fmt(&self.name, fmt)
2302    }
2303}
2304
2305impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2306    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2307        fmt::Display::fmt(&self.name, fmt)
2308    }
2309}
2310
2311#[derive(Debug, Default, Copy, Clone)]
2312pub struct InferVarInfo {
2313    /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2314    /// obligation, where:
2315    ///
2316    ///  * `Foo` is not `Sized`
2317    ///  * `(): Foo` may be satisfied
2318    pub self_in_trait: bool,
2319    /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2320    /// _>::AssocType = ?T`
2321    pub output: bool,
2322}
2323
2324/// The constituent parts of a type level constant of kind ADT or array.
2325#[derive(Copy, Clone, Debug, HashStable)]
2326pub struct DestructuredConst<'tcx> {
2327    pub variant: Option<VariantIdx>,
2328    pub fields: &'tcx [ty::Const<'tcx>],
2329}
2330
2331// Some types are used a lot. Make sure they don't unintentionally get bigger.
2332#[cfg(target_pointer_width = "64")]
2333mod size_asserts {
2334    use rustc_data_structures::static_assert_size;
2335
2336    use super::*;
2337    // tidy-alphabetical-start
2338    static_assert_size!(PredicateKind<'_>, 32);
2339    static_assert_size!(WithCachedTypeInfo<TyKind<'_>>, 48);
2340    // tidy-alphabetical-end
2341}