rustc_middle/ty/
adt.rs

1use std::cell::RefCell;
2use std::hash::{Hash, Hasher};
3use std::ops::Range;
4use std::str;
5
6use rustc_abi::{FIRST_VARIANT, ReprOptions, VariantIdx};
7use rustc_data_structures::fingerprint::Fingerprint;
8use rustc_data_structures::fx::FxHashMap;
9use rustc_data_structures::intern::Interned;
10use rustc_data_structures::stable_hasher::{HashStable, HashingControls, StableHasher};
11use rustc_errors::ErrorGuaranteed;
12use rustc_hir::def::{CtorKind, DefKind, Res};
13use rustc_hir::def_id::DefId;
14use rustc_hir::{self as hir, LangItem};
15use rustc_index::{IndexSlice, IndexVec};
16use rustc_macros::{HashStable, TyDecodable, TyEncodable};
17use rustc_query_system::ich::StableHashingContext;
18use rustc_session::DataTypeKind;
19use rustc_span::sym;
20use rustc_type_ir::solve::AdtDestructorKind;
21use tracing::{debug, info, trace};
22
23use super::{
24    AsyncDestructor, Destructor, FieldDef, GenericPredicates, Ty, TyCtxt, VariantDef, VariantDiscr,
25};
26use crate::mir::interpret::ErrorHandled;
27use crate::ty;
28use crate::ty::util::{Discr, IntTypeExt};
29
30#[derive(Clone, Copy, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
31pub struct AdtFlags(u16);
32bitflags::bitflags! {
33    impl AdtFlags: u16 {
34        const NO_ADT_FLAGS        = 0;
35        /// Indicates whether the ADT is an enum.
36        const IS_ENUM             = 1 << 0;
37        /// Indicates whether the ADT is a union.
38        const IS_UNION            = 1 << 1;
39        /// Indicates whether the ADT is a struct.
40        const IS_STRUCT           = 1 << 2;
41        /// Indicates whether the ADT is a struct and has a constructor.
42        const HAS_CTOR            = 1 << 3;
43        /// Indicates whether the type is `PhantomData`.
44        const IS_PHANTOM_DATA     = 1 << 4;
45        /// Indicates whether the type has a `#[fundamental]` attribute.
46        const IS_FUNDAMENTAL      = 1 << 5;
47        /// Indicates whether the type is `Box`.
48        const IS_BOX              = 1 << 6;
49        /// Indicates whether the type is `ManuallyDrop`.
50        const IS_MANUALLY_DROP    = 1 << 7;
51        /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
52        /// (i.e., this flag is never set unless this ADT is an enum).
53        const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
54        /// Indicates whether the type is `UnsafeCell`.
55        const IS_UNSAFE_CELL              = 1 << 9;
56        /// Indicates whether the type is `UnsafePinned`.
57        const IS_UNSAFE_PINNED              = 1 << 10;
58    }
59}
60rustc_data_structures::external_bitflags_debug! { AdtFlags }
61
62/// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
63///
64/// These are all interned (by `mk_adt_def`) into the global arena.
65///
66/// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
67/// This is slightly wrong because `union`s are not ADTs.
68/// Moreover, Rust only allows recursive data types through indirection.
69///
70/// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
71///
72/// # Recursive types
73///
74/// It may seem impossible to represent recursive types using [`Ty`],
75/// since [`TyKind::Adt`] includes [`AdtDef`], which includes its fields,
76/// creating a cycle. However, `AdtDef` does not actually include the *types*
77/// of its fields; it includes just their [`DefId`]s.
78///
79/// [`TyKind::Adt`]: ty::TyKind::Adt
80///
81/// For example, the following type:
82///
83/// ```
84/// struct S { x: Box<S> }
85/// ```
86///
87/// is essentially represented with [`Ty`] as the following pseudocode:
88///
89/// ```ignore (illustrative)
90/// struct S { x }
91/// ```
92///
93/// where `x` here represents the `DefId` of `S.x`. Then, the `DefId`
94/// can be used with [`TyCtxt::type_of()`] to get the type of the field.
95#[derive(TyEncodable, TyDecodable)]
96pub struct AdtDefData {
97    /// The `DefId` of the struct, enum or union item.
98    pub did: DefId,
99    /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
100    variants: IndexVec<VariantIdx, VariantDef>,
101    /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
102    flags: AdtFlags,
103    /// Repr options provided by the user.
104    repr: ReprOptions,
105}
106
107impl PartialEq for AdtDefData {
108    #[inline]
109    fn eq(&self, other: &Self) -> bool {
110        // There should be only one `AdtDefData` for each `def_id`, therefore
111        // it is fine to implement `PartialEq` only based on `def_id`.
112        //
113        // Below, we exhaustively destructure `self` and `other` so that if the
114        // definition of `AdtDefData` changes, a compile-error will be produced,
115        // reminding us to revisit this assumption.
116
117        let Self { did: self_def_id, variants: _, flags: _, repr: _ } = self;
118        let Self { did: other_def_id, variants: _, flags: _, repr: _ } = other;
119
120        let res = self_def_id == other_def_id;
121
122        // Double check that implicit assumption detailed above.
123        if cfg!(debug_assertions) && res {
124            let deep = self.flags == other.flags
125                && self.repr == other.repr
126                && self.variants == other.variants;
127            assert!(deep, "AdtDefData for the same def-id has differing data");
128        }
129
130        res
131    }
132}
133
134impl Eq for AdtDefData {}
135
136/// There should be only one AdtDef for each `did`, therefore
137/// it is fine to implement `Hash` only based on `did`.
138impl Hash for AdtDefData {
139    #[inline]
140    fn hash<H: Hasher>(&self, s: &mut H) {
141        self.did.hash(s)
142    }
143}
144
145impl<'a> HashStable<StableHashingContext<'a>> for AdtDefData {
146    fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
147        thread_local! {
148            static CACHE: RefCell<FxHashMap<(usize, HashingControls), Fingerprint>> = Default::default();
149        }
150
151        let hash: Fingerprint = CACHE.with(|cache| {
152            let addr = self as *const AdtDefData as usize;
153            let hashing_controls = hcx.hashing_controls();
154            *cache.borrow_mut().entry((addr, hashing_controls)).or_insert_with(|| {
155                let ty::AdtDefData { did, ref variants, ref flags, ref repr } = *self;
156
157                let mut hasher = StableHasher::new();
158                did.hash_stable(hcx, &mut hasher);
159                variants.hash_stable(hcx, &mut hasher);
160                flags.hash_stable(hcx, &mut hasher);
161                repr.hash_stable(hcx, &mut hasher);
162
163                hasher.finish()
164            })
165        });
166
167        hash.hash_stable(hcx, hasher);
168    }
169}
170
171#[derive(Copy, Clone, PartialEq, Eq, Hash, HashStable)]
172#[rustc_pass_by_value]
173pub struct AdtDef<'tcx>(pub Interned<'tcx, AdtDefData>);
174
175impl<'tcx> AdtDef<'tcx> {
176    #[inline]
177    pub fn did(self) -> DefId {
178        self.0.0.did
179    }
180
181    #[inline]
182    pub fn variants(self) -> &'tcx IndexSlice<VariantIdx, VariantDef> {
183        &self.0.0.variants
184    }
185
186    #[inline]
187    pub fn variant(self, idx: VariantIdx) -> &'tcx VariantDef {
188        &self.0.0.variants[idx]
189    }
190
191    #[inline]
192    pub fn flags(self) -> AdtFlags {
193        self.0.0.flags
194    }
195
196    #[inline]
197    pub fn repr(self) -> ReprOptions {
198        self.0.0.repr
199    }
200}
201
202impl<'tcx> rustc_type_ir::inherent::AdtDef<TyCtxt<'tcx>> for AdtDef<'tcx> {
203    fn def_id(self) -> DefId {
204        self.did()
205    }
206
207    fn is_struct(self) -> bool {
208        self.is_struct()
209    }
210
211    fn struct_tail_ty(self, interner: TyCtxt<'tcx>) -> Option<ty::EarlyBinder<'tcx, Ty<'tcx>>> {
212        Some(interner.type_of(self.non_enum_variant().tail_opt()?.did))
213    }
214
215    fn is_phantom_data(self) -> bool {
216        self.is_phantom_data()
217    }
218
219    fn is_manually_drop(self) -> bool {
220        self.is_manually_drop()
221    }
222
223    fn all_field_tys(
224        self,
225        tcx: TyCtxt<'tcx>,
226    ) -> ty::EarlyBinder<'tcx, impl IntoIterator<Item = Ty<'tcx>>> {
227        ty::EarlyBinder::bind(
228            self.all_fields().map(move |field| tcx.type_of(field.did).skip_binder()),
229        )
230    }
231
232    fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> Option<ty::EarlyBinder<'tcx, Ty<'tcx>>> {
233        self.sized_constraint(tcx)
234    }
235
236    fn is_fundamental(self) -> bool {
237        self.is_fundamental()
238    }
239
240    fn destructor(self, tcx: TyCtxt<'tcx>) -> Option<AdtDestructorKind> {
241        Some(match tcx.constness(self.destructor(tcx)?.did) {
242            hir::Constness::Const => AdtDestructorKind::Const,
243            hir::Constness::NotConst => AdtDestructorKind::NotConst,
244        })
245    }
246}
247
248#[derive(Copy, Clone, Debug, Eq, PartialEq, HashStable, TyEncodable, TyDecodable)]
249pub enum AdtKind {
250    Struct,
251    Union,
252    Enum,
253}
254
255impl From<AdtKind> for DataTypeKind {
256    fn from(val: AdtKind) -> Self {
257        match val {
258            AdtKind::Struct => DataTypeKind::Struct,
259            AdtKind::Union => DataTypeKind::Union,
260            AdtKind::Enum => DataTypeKind::Enum,
261        }
262    }
263}
264
265impl AdtDefData {
266    /// Creates a new `AdtDefData`.
267    pub(super) fn new(
268        tcx: TyCtxt<'_>,
269        did: DefId,
270        kind: AdtKind,
271        variants: IndexVec<VariantIdx, VariantDef>,
272        repr: ReprOptions,
273    ) -> Self {
274        debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
275        let mut flags = AdtFlags::NO_ADT_FLAGS;
276
277        if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
278            debug!("found non-exhaustive variant list for {:?}", did);
279            flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
280        }
281
282        flags |= match kind {
283            AdtKind::Enum => AdtFlags::IS_ENUM,
284            AdtKind::Union => AdtFlags::IS_UNION,
285            AdtKind::Struct => AdtFlags::IS_STRUCT,
286        };
287
288        if kind == AdtKind::Struct && variants[FIRST_VARIANT].ctor.is_some() {
289            flags |= AdtFlags::HAS_CTOR;
290        }
291
292        if tcx.has_attr(did, sym::fundamental) {
293            flags |= AdtFlags::IS_FUNDAMENTAL;
294        }
295        if tcx.is_lang_item(did, LangItem::PhantomData) {
296            flags |= AdtFlags::IS_PHANTOM_DATA;
297        }
298        if tcx.is_lang_item(did, LangItem::OwnedBox) {
299            flags |= AdtFlags::IS_BOX;
300        }
301        if tcx.is_lang_item(did, LangItem::ManuallyDrop) {
302            flags |= AdtFlags::IS_MANUALLY_DROP;
303        }
304        if tcx.is_lang_item(did, LangItem::UnsafeCell) {
305            flags |= AdtFlags::IS_UNSAFE_CELL;
306        }
307        if tcx.is_lang_item(did, LangItem::UnsafePinned) {
308            flags |= AdtFlags::IS_UNSAFE_PINNED;
309        }
310
311        AdtDefData { did, variants, flags, repr }
312    }
313}
314
315impl<'tcx> AdtDef<'tcx> {
316    /// Returns `true` if this is a struct.
317    #[inline]
318    pub fn is_struct(self) -> bool {
319        self.flags().contains(AdtFlags::IS_STRUCT)
320    }
321
322    /// Returns `true` if this is a union.
323    #[inline]
324    pub fn is_union(self) -> bool {
325        self.flags().contains(AdtFlags::IS_UNION)
326    }
327
328    /// Returns `true` if this is an enum.
329    #[inline]
330    pub fn is_enum(self) -> bool {
331        self.flags().contains(AdtFlags::IS_ENUM)
332    }
333
334    /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
335    ///
336    /// Note that this function will return `true` even if the ADT has been
337    /// defined in the crate currently being compiled. If that's not what you
338    /// want, see [`Self::variant_list_has_applicable_non_exhaustive`].
339    #[inline]
340    pub fn is_variant_list_non_exhaustive(self) -> bool {
341        self.flags().contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
342    }
343
344    /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`
345    /// and has been defined in another crate.
346    #[inline]
347    pub fn variant_list_has_applicable_non_exhaustive(self) -> bool {
348        self.is_variant_list_non_exhaustive() && !self.did().is_local()
349    }
350
351    /// Returns the kind of the ADT.
352    #[inline]
353    pub fn adt_kind(self) -> AdtKind {
354        if self.is_enum() {
355            AdtKind::Enum
356        } else if self.is_union() {
357            AdtKind::Union
358        } else {
359            AdtKind::Struct
360        }
361    }
362
363    /// Returns a description of this abstract data type.
364    pub fn descr(self) -> &'static str {
365        match self.adt_kind() {
366            AdtKind::Struct => "struct",
367            AdtKind::Union => "union",
368            AdtKind::Enum => "enum",
369        }
370    }
371
372    /// Returns a description of a variant of this abstract data type.
373    #[inline]
374    pub fn variant_descr(self) -> &'static str {
375        match self.adt_kind() {
376            AdtKind::Struct => "struct",
377            AdtKind::Union => "union",
378            AdtKind::Enum => "variant",
379        }
380    }
381
382    /// If this function returns `true`, it implies that `is_struct` must return `true`.
383    #[inline]
384    pub fn has_ctor(self) -> bool {
385        self.flags().contains(AdtFlags::HAS_CTOR)
386    }
387
388    /// Returns `true` if this type is `#[fundamental]` for the purposes
389    /// of coherence checking.
390    #[inline]
391    pub fn is_fundamental(self) -> bool {
392        self.flags().contains(AdtFlags::IS_FUNDAMENTAL)
393    }
394
395    /// Returns `true` if this is `PhantomData<T>`.
396    #[inline]
397    pub fn is_phantom_data(self) -> bool {
398        self.flags().contains(AdtFlags::IS_PHANTOM_DATA)
399    }
400
401    /// Returns `true` if this is `Box<T>`.
402    #[inline]
403    pub fn is_box(self) -> bool {
404        self.flags().contains(AdtFlags::IS_BOX)
405    }
406
407    /// Returns `true` if this is `UnsafeCell<T>`.
408    #[inline]
409    pub fn is_unsafe_cell(self) -> bool {
410        self.flags().contains(AdtFlags::IS_UNSAFE_CELL)
411    }
412
413    /// Returns `true` if this is `UnsafePinned<T>`.
414    #[inline]
415    pub fn is_unsafe_pinned(self) -> bool {
416        self.flags().contains(AdtFlags::IS_UNSAFE_PINNED)
417    }
418
419    /// Returns `true` if this is `ManuallyDrop<T>`.
420    #[inline]
421    pub fn is_manually_drop(self) -> bool {
422        self.flags().contains(AdtFlags::IS_MANUALLY_DROP)
423    }
424
425    /// Returns `true` if this type has a destructor.
426    pub fn has_dtor(self, tcx: TyCtxt<'tcx>) -> bool {
427        self.destructor(tcx).is_some()
428    }
429
430    /// Asserts this is a struct or union and returns its unique variant.
431    pub fn non_enum_variant(self) -> &'tcx VariantDef {
432        assert!(self.is_struct() || self.is_union());
433        self.variant(FIRST_VARIANT)
434    }
435
436    #[inline]
437    pub fn predicates(self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
438        tcx.predicates_of(self.did())
439    }
440
441    /// Returns an iterator over all fields contained
442    /// by this ADT (nested unnamed fields are not expanded).
443    #[inline]
444    pub fn all_fields(self) -> impl Iterator<Item = &'tcx FieldDef> + Clone {
445        self.variants().iter().flat_map(|v| v.fields.iter())
446    }
447
448    /// Whether the ADT lacks fields. Note that this includes uninhabited enums,
449    /// e.g., `enum Void {}` is considered payload free as well.
450    pub fn is_payloadfree(self) -> bool {
451        // Treat the ADT as not payload-free if arbitrary_enum_discriminant is used (#88621).
452        // This would disallow the following kind of enum from being casted into integer.
453        // ```
454        // enum Enum {
455        //    Foo() = 1,
456        //    Bar{} = 2,
457        //    Baz = 3,
458        // }
459        // ```
460        if self.variants().iter().any(|v| {
461            matches!(v.discr, VariantDiscr::Explicit(_)) && v.ctor_kind() != Some(CtorKind::Const)
462        }) {
463            return false;
464        }
465        self.variants().iter().all(|v| v.fields.is_empty())
466    }
467
468    /// Return a `VariantDef` given a variant id.
469    pub fn variant_with_id(self, vid: DefId) -> &'tcx VariantDef {
470        self.variants().iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
471    }
472
473    /// Return a `VariantDef` given a constructor id.
474    pub fn variant_with_ctor_id(self, cid: DefId) -> &'tcx VariantDef {
475        self.variants()
476            .iter()
477            .find(|v| v.ctor_def_id() == Some(cid))
478            .expect("variant_with_ctor_id: unknown variant")
479    }
480
481    /// Return the index of `VariantDef` given a variant id.
482    #[inline]
483    pub fn variant_index_with_id(self, vid: DefId) -> VariantIdx {
484        self.variants()
485            .iter_enumerated()
486            .find(|(_, v)| v.def_id == vid)
487            .expect("variant_index_with_id: unknown variant")
488            .0
489    }
490
491    /// Return the index of `VariantDef` given a constructor id.
492    pub fn variant_index_with_ctor_id(self, cid: DefId) -> VariantIdx {
493        self.variants()
494            .iter_enumerated()
495            .find(|(_, v)| v.ctor_def_id() == Some(cid))
496            .expect("variant_index_with_ctor_id: unknown variant")
497            .0
498    }
499
500    pub fn variant_of_res(self, res: Res) -> &'tcx VariantDef {
501        match res {
502            Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
503            Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
504            Res::Def(DefKind::Struct, _)
505            | Res::Def(DefKind::Union, _)
506            | Res::Def(DefKind::TyAlias, _)
507            | Res::Def(DefKind::AssocTy, _)
508            | Res::SelfTyParam { .. }
509            | Res::SelfTyAlias { .. }
510            | Res::SelfCtor(..) => self.non_enum_variant(),
511            _ => bug!("unexpected res {:?} in variant_of_res", res),
512        }
513    }
514
515    #[inline]
516    pub fn eval_explicit_discr(
517        self,
518        tcx: TyCtxt<'tcx>,
519        expr_did: DefId,
520    ) -> Result<Discr<'tcx>, ErrorGuaranteed> {
521        assert!(self.is_enum());
522
523        let repr_type = self.repr().discr_type();
524        match tcx.const_eval_poly(expr_did) {
525            Ok(val) => {
526                let typing_env = ty::TypingEnv::post_analysis(tcx, expr_did);
527                let ty = repr_type.to_ty(tcx);
528                if let Some(b) = val.try_to_bits_for_ty(tcx, typing_env, ty) {
529                    trace!("discriminants: {} ({:?})", b, repr_type);
530                    Ok(Discr { val: b, ty })
531                } else {
532                    info!("invalid enum discriminant: {:#?}", val);
533                    let guar = tcx.dcx().emit_err(crate::error::ConstEvalNonIntError {
534                        span: tcx.def_span(expr_did),
535                    });
536                    Err(guar)
537                }
538            }
539            Err(err) => {
540                let guar = match err {
541                    ErrorHandled::Reported(info, _) => info.into(),
542                    ErrorHandled::TooGeneric(..) => tcx.dcx().span_delayed_bug(
543                        tcx.def_span(expr_did),
544                        "enum discriminant depends on generics",
545                    ),
546                };
547                Err(guar)
548            }
549        }
550    }
551
552    #[inline]
553    pub fn discriminants(
554        self,
555        tcx: TyCtxt<'tcx>,
556    ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> {
557        assert!(self.is_enum());
558        let repr_type = self.repr().discr_type();
559        let initial = repr_type.initial_discriminant(tcx);
560        let mut prev_discr = None::<Discr<'tcx>>;
561        self.variants().iter_enumerated().map(move |(i, v)| {
562            let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
563            if let VariantDiscr::Explicit(expr_did) = v.discr {
564                if let Ok(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
565                    discr = new_discr;
566                }
567            }
568            prev_discr = Some(discr);
569
570            (i, discr)
571        })
572    }
573
574    #[inline]
575    pub fn variant_range(self) -> Range<VariantIdx> {
576        FIRST_VARIANT..self.variants().next_index()
577    }
578
579    /// Computes the discriminant value used by a specific variant.
580    /// Unlike `discriminants`, this is (amortized) constant-time,
581    /// only doing at most one query for evaluating an explicit
582    /// discriminant (the last one before the requested variant),
583    /// assuming there are no constant-evaluation errors there.
584    #[inline]
585    pub fn discriminant_for_variant(
586        self,
587        tcx: TyCtxt<'tcx>,
588        variant_index: VariantIdx,
589    ) -> Discr<'tcx> {
590        assert!(self.is_enum());
591        let (val, offset) = self.discriminant_def_for_variant(variant_index);
592        let explicit_value = if let Some(expr_did) = val
593            && let Ok(val) = self.eval_explicit_discr(tcx, expr_did)
594        {
595            val
596        } else {
597            self.repr().discr_type().initial_discriminant(tcx)
598        };
599        explicit_value.checked_add(tcx, offset as u128).0
600    }
601
602    /// Yields a `DefId` for the discriminant and an offset to add to it
603    /// Alternatively, if there is no explicit discriminant, returns the
604    /// inferred discriminant directly.
605    pub fn discriminant_def_for_variant(self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
606        assert!(!self.variants().is_empty());
607        let mut explicit_index = variant_index.as_u32();
608        let expr_did;
609        loop {
610            match self.variant(VariantIdx::from_u32(explicit_index)).discr {
611                ty::VariantDiscr::Relative(0) => {
612                    expr_did = None;
613                    break;
614                }
615                ty::VariantDiscr::Relative(distance) => {
616                    explicit_index -= distance;
617                }
618                ty::VariantDiscr::Explicit(did) => {
619                    expr_did = Some(did);
620                    break;
621                }
622            }
623        }
624        (expr_did, variant_index.as_u32() - explicit_index)
625    }
626
627    pub fn destructor(self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
628        tcx.adt_destructor(self.did())
629    }
630
631    // FIXME: consider combining this method with `AdtDef::destructor` and removing
632    // this version
633    pub fn async_destructor(self, tcx: TyCtxt<'tcx>) -> Option<AsyncDestructor> {
634        tcx.adt_async_destructor(self.did())
635    }
636
637    /// Returns a type such that `Self: Sized` if and only if that type is `Sized`,
638    /// or `None` if the type is always sized.
639    pub fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> Option<ty::EarlyBinder<'tcx, Ty<'tcx>>> {
640        if self.is_struct() { tcx.adt_sized_constraint(self.did()) } else { None }
641    }
642}
643
644#[derive(Clone, Copy, Debug, HashStable)]
645pub enum Representability {
646    Representable,
647    Infinite(ErrorGuaranteed),
648}
rustc_middle/ty/adt.rs

rustc_middle/ty/
adt.rs
