1 use crate::mir::interpret::ErrorHandled;
3 use crate::ty::util::{Discr, IntTypeExt};
4 use rustc_data_structures::captures::Captures;
5 use rustc_data_structures::fingerprint::Fingerprint;
6 use rustc_data_structures::fx::FxHashMap;
7 use rustc_data_structures::intern::Interned;
8 use rustc_data_structures::stable_hasher::HashingControls;
9 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
11 use rustc_hir::def::{CtorKind, DefKind, Res};
12 use rustc_hir::def_id::DefId;
13 use rustc_index::vec::{Idx, IndexVec};
14 use rustc_query_system::ich::StableHashingContext;
15 use rustc_session::DataTypeKind;
16 use rustc_span::symbol::sym;
17 use rustc_target::abi::VariantIdx;
19 use std::cell::RefCell;
20 use std::cmp::Ordering;
21 use std::hash::{Hash, Hasher};
26 Destructor, FieldDef, GenericPredicates, ReprOptions, Ty, TyCtxt, VariantDef, VariantDiscr,
29 #[derive(Copy, Clone, HashStable, Debug)]
30 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
33 #[derive(HashStable, TyEncodable, TyDecodable)]
34 pub struct AdtFlags: u32 {
35 const NO_ADT_FLAGS = 0;
36 /// Indicates whether the ADT is an enum.
37 const IS_ENUM = 1 << 0;
38 /// Indicates whether the ADT is a union.
39 const IS_UNION = 1 << 1;
40 /// Indicates whether the ADT is a struct.
41 const IS_STRUCT = 1 << 2;
42 /// Indicates whether the ADT is a struct and has a constructor.
43 const HAS_CTOR = 1 << 3;
44 /// Indicates whether the type is `PhantomData`.
45 const IS_PHANTOM_DATA = 1 << 4;
46 /// Indicates whether the type has a `#[fundamental]` attribute.
47 const IS_FUNDAMENTAL = 1 << 5;
48 /// Indicates whether the type is `Box`.
49 const IS_BOX = 1 << 6;
50 /// Indicates whether the type is `ManuallyDrop`.
51 const IS_MANUALLY_DROP = 1 << 7;
52 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
53 /// (i.e., this flag is never set unless this ADT is an enum).
54 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
55 /// Indicates whether the type is `UnsafeCell`.
56 const IS_UNSAFE_CELL = 1 << 9;
60 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
62 /// These are all interned (by `alloc_adt_def`) into the global arena.
64 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
65 /// This is slightly wrong because `union`s are not ADTs.
66 /// Moreover, Rust only allows recursive data types through indirection.
68 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
72 /// It may seem impossible to represent recursive types using [`Ty`],
73 /// since [`TyKind::Adt`] includes [`AdtDef`], which includes its fields,
74 /// creating a cycle. However, `AdtDef` does not actually include the *types*
75 /// of its fields; it includes just their [`DefId`]s.
77 /// [`TyKind::Adt`]: ty::TyKind::Adt
79 /// For example, the following type:
82 /// struct S { x: Box<S> }
85 /// is essentially represented with [`Ty`] as the following pseudocode:
87 /// ```ignore (illustrative)
91 /// where `x` here represents the `DefId` of `S.x`. Then, the `DefId`
92 /// can be used with [`TyCtxt::type_of()`] to get the type of the field.
93 #[derive(TyEncodable, TyDecodable)]
94 pub struct AdtDefData {
95 /// The `DefId` of the struct, enum or union item.
97 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
98 variants: IndexVec<VariantIdx, VariantDef>,
99 /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
101 /// Repr options provided by the user.
105 impl PartialOrd for AdtDefData {
106 fn partial_cmp(&self, other: &AdtDefData) -> Option<Ordering> {
107 Some(self.cmp(&other))
111 /// There should be only one AdtDef for each `did`, therefore
112 /// it is fine to implement `Ord` only based on `did`.
113 impl Ord for AdtDefData {
114 fn cmp(&self, other: &AdtDefData) -> Ordering {
115 self.did.cmp(&other.did)
119 /// There should be only one AdtDef for each `did`, therefore
120 /// it is fine to implement `PartialEq` only based on `did`.
121 impl PartialEq for AdtDefData {
123 fn eq(&self, other: &Self) -> bool {
124 self.did == other.did
128 impl Eq for AdtDefData {}
130 /// There should be only one AdtDef for each `did`, therefore
131 /// it is fine to implement `Hash` only based on `did`.
132 impl Hash for AdtDefData {
134 fn hash<H: Hasher>(&self, s: &mut H) {
139 impl<'a> HashStable<StableHashingContext<'a>> for AdtDefData {
140 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
142 static CACHE: RefCell<FxHashMap<(usize, HashingControls), Fingerprint>> = Default::default();
145 let hash: Fingerprint = CACHE.with(|cache| {
146 let addr = self as *const AdtDefData as usize;
147 let hashing_controls = hcx.hashing_controls();
148 *cache.borrow_mut().entry((addr, hashing_controls)).or_insert_with(|| {
149 let ty::AdtDefData { did, ref variants, ref flags, ref repr } = *self;
151 let mut hasher = StableHasher::new();
152 did.hash_stable(hcx, &mut hasher);
153 variants.hash_stable(hcx, &mut hasher);
154 flags.hash_stable(hcx, &mut hasher);
155 repr.hash_stable(hcx, &mut hasher);
161 hash.hash_stable(hcx, hasher);
165 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd, HashStable)]
166 #[rustc_pass_by_value]
167 pub struct AdtDef<'tcx>(pub Interned<'tcx, AdtDefData>);
169 impl<'tcx> AdtDef<'tcx> {
171 pub fn did(self) -> DefId {
176 pub fn variants(self) -> &'tcx IndexVec<VariantIdx, VariantDef> {
181 pub fn variant(self, idx: VariantIdx) -> &'tcx VariantDef {
182 &self.0.0.variants[idx]
186 pub fn flags(self) -> AdtFlags {
191 pub fn repr(self) -> ReprOptions {
196 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, TyEncodable, TyDecodable)]
203 impl Into<DataTypeKind> for AdtKind {
204 fn into(self) -> DataTypeKind {
206 AdtKind::Struct => DataTypeKind::Struct,
207 AdtKind::Union => DataTypeKind::Union,
208 AdtKind::Enum => DataTypeKind::Enum,
214 /// Creates a new `AdtDefData`.
219 variants: IndexVec<VariantIdx, VariantDef>,
222 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
223 let mut flags = AdtFlags::NO_ADT_FLAGS;
225 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
226 debug!("found non-exhaustive variant list for {:?}", did);
227 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
230 flags |= match kind {
231 AdtKind::Enum => AdtFlags::IS_ENUM,
232 AdtKind::Union => AdtFlags::IS_UNION,
233 AdtKind::Struct => AdtFlags::IS_STRUCT,
236 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
237 flags |= AdtFlags::HAS_CTOR;
240 if tcx.has_attr(did, sym::fundamental) {
241 flags |= AdtFlags::IS_FUNDAMENTAL;
243 if Some(did) == tcx.lang_items().phantom_data() {
244 flags |= AdtFlags::IS_PHANTOM_DATA;
246 if Some(did) == tcx.lang_items().owned_box() {
247 flags |= AdtFlags::IS_BOX;
249 if Some(did) == tcx.lang_items().manually_drop() {
250 flags |= AdtFlags::IS_MANUALLY_DROP;
252 if Some(did) == tcx.lang_items().unsafe_cell_type() {
253 flags |= AdtFlags::IS_UNSAFE_CELL;
256 AdtDefData { did, variants, flags, repr }
260 impl<'tcx> AdtDef<'tcx> {
261 /// Returns `true` if this is a struct.
263 pub fn is_struct(self) -> bool {
264 self.flags().contains(AdtFlags::IS_STRUCT)
267 /// Returns `true` if this is a union.
269 pub fn is_union(self) -> bool {
270 self.flags().contains(AdtFlags::IS_UNION)
273 /// Returns `true` if this is an enum.
275 pub fn is_enum(self) -> bool {
276 self.flags().contains(AdtFlags::IS_ENUM)
279 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
281 pub fn is_variant_list_non_exhaustive(self) -> bool {
282 self.flags().contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
285 /// Returns the kind of the ADT.
287 pub fn adt_kind(self) -> AdtKind {
290 } else if self.is_union() {
297 /// Returns a description of this abstract data type.
298 pub fn descr(self) -> &'static str {
299 match self.adt_kind() {
300 AdtKind::Struct => "struct",
301 AdtKind::Union => "union",
302 AdtKind::Enum => "enum",
306 /// Returns a description of a variant of this abstract data type.
308 pub fn variant_descr(self) -> &'static str {
309 match self.adt_kind() {
310 AdtKind::Struct => "struct",
311 AdtKind::Union => "union",
312 AdtKind::Enum => "variant",
316 /// If this function returns `true`, it implies that `is_struct` must return `true`.
318 pub fn has_ctor(self) -> bool {
319 self.flags().contains(AdtFlags::HAS_CTOR)
322 /// Returns `true` if this type is `#[fundamental]` for the purposes
323 /// of coherence checking.
325 pub fn is_fundamental(self) -> bool {
326 self.flags().contains(AdtFlags::IS_FUNDAMENTAL)
329 /// Returns `true` if this is `PhantomData<T>`.
331 pub fn is_phantom_data(self) -> bool {
332 self.flags().contains(AdtFlags::IS_PHANTOM_DATA)
335 /// Returns `true` if this is Box<T>.
337 pub fn is_box(self) -> bool {
338 self.flags().contains(AdtFlags::IS_BOX)
341 /// Returns `true` if this is UnsafeCell<T>.
343 pub fn is_unsafe_cell(self) -> bool {
344 self.flags().contains(AdtFlags::IS_UNSAFE_CELL)
347 /// Returns `true` if this is `ManuallyDrop<T>`.
349 pub fn is_manually_drop(self) -> bool {
350 self.flags().contains(AdtFlags::IS_MANUALLY_DROP)
353 /// Returns `true` if this type has a destructor.
354 pub fn has_dtor(self, tcx: TyCtxt<'tcx>) -> bool {
355 self.destructor(tcx).is_some()
358 pub fn has_non_const_dtor(self, tcx: TyCtxt<'tcx>) -> bool {
359 matches!(self.destructor(tcx), Some(Destructor { constness: hir::Constness::NotConst, .. }))
362 /// Asserts this is a struct or union and returns its unique variant.
363 pub fn non_enum_variant(self) -> &'tcx VariantDef {
364 assert!(self.is_struct() || self.is_union());
365 &self.variant(VariantIdx::new(0))
369 pub fn predicates(self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
370 tcx.predicates_of(self.did())
373 /// Returns an iterator over all fields contained
376 pub fn all_fields(self) -> impl Iterator<Item = &'tcx FieldDef> + Clone {
377 self.variants().iter().flat_map(|v| v.fields.iter())
380 /// Whether the ADT lacks fields. Note that this includes uninhabited enums,
381 /// e.g., `enum Void {}` is considered payload free as well.
382 pub fn is_payloadfree(self) -> bool {
383 // Treat the ADT as not payload-free if arbitrary_enum_discriminant is used (#88621).
384 // This would disallow the following kind of enum from being casted into integer.
395 .any(|v| matches!(v.discr, VariantDiscr::Explicit(_)) && v.ctor_kind != CtorKind::Const)
399 self.variants().iter().all(|v| v.fields.is_empty())
402 /// Return a `VariantDef` given a variant id.
403 pub fn variant_with_id(self, vid: DefId) -> &'tcx VariantDef {
404 self.variants().iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
407 /// Return a `VariantDef` given a constructor id.
408 pub fn variant_with_ctor_id(self, cid: DefId) -> &'tcx VariantDef {
411 .find(|v| v.ctor_def_id == Some(cid))
412 .expect("variant_with_ctor_id: unknown variant")
415 /// Return the index of `VariantDef` given a variant id.
416 pub fn variant_index_with_id(self, vid: DefId) -> VariantIdx {
419 .find(|(_, v)| v.def_id == vid)
420 .expect("variant_index_with_id: unknown variant")
424 /// Return the index of `VariantDef` given a constructor id.
425 pub fn variant_index_with_ctor_id(self, cid: DefId) -> VariantIdx {
428 .find(|(_, v)| v.ctor_def_id == Some(cid))
429 .expect("variant_index_with_ctor_id: unknown variant")
433 pub fn variant_of_res(self, res: Res) -> &'tcx VariantDef {
435 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
436 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
437 Res::Def(DefKind::Struct, _)
438 | Res::Def(DefKind::Union, _)
439 | Res::Def(DefKind::TyAlias, _)
440 | Res::Def(DefKind::AssocTy, _)
441 | Res::SelfTyParam { .. }
442 | Res::SelfTyAlias { .. }
443 | Res::SelfCtor(..) => self.non_enum_variant(),
444 _ => bug!("unexpected res {:?} in variant_of_res", res),
449 pub fn eval_explicit_discr(self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
450 assert!(self.is_enum());
451 let param_env = tcx.param_env(expr_did);
452 let repr_type = self.repr().discr_type();
453 match tcx.const_eval_poly(expr_did) {
455 let ty = repr_type.to_ty(tcx);
456 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
457 trace!("discriminants: {} ({:?})", b, repr_type);
458 Some(Discr { val: b, ty })
460 info!("invalid enum discriminant: {:#?}", val);
461 tcx.sess.emit_err(crate::error::ConstEvalNonIntError {
462 span: tcx.def_span(expr_did),
468 let msg = match err {
469 ErrorHandled::Reported(_) | ErrorHandled::Linted => {
470 "enum discriminant evaluation failed"
472 ErrorHandled::TooGeneric => "enum discriminant depends on generics",
474 tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg);
481 pub fn discriminants(
484 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
485 assert!(self.is_enum());
486 let repr_type = self.repr().discr_type();
487 let initial = repr_type.initial_discriminant(tcx);
488 let mut prev_discr = None::<Discr<'tcx>>;
489 self.variants().iter_enumerated().map(move |(i, v)| {
490 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
491 if let VariantDiscr::Explicit(expr_did) = v.discr {
492 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
496 prev_discr = Some(discr);
503 pub fn variant_range(self) -> Range<VariantIdx> {
504 VariantIdx::new(0)..VariantIdx::new(self.variants().len())
507 /// Computes the discriminant value used by a specific variant.
508 /// Unlike `discriminants`, this is (amortized) constant-time,
509 /// only doing at most one query for evaluating an explicit
510 /// discriminant (the last one before the requested variant),
511 /// assuming there are no constant-evaluation errors there.
513 pub fn discriminant_for_variant(
516 variant_index: VariantIdx,
518 assert!(self.is_enum());
519 let (val, offset) = self.discriminant_def_for_variant(variant_index);
520 let explicit_value = val
521 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
522 .unwrap_or_else(|| self.repr().discr_type().initial_discriminant(tcx));
523 explicit_value.checked_add(tcx, offset as u128).0
526 /// Yields a `DefId` for the discriminant and an offset to add to it
527 /// Alternatively, if there is no explicit discriminant, returns the
528 /// inferred discriminant directly.
529 pub fn discriminant_def_for_variant(self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
530 assert!(!self.variants().is_empty());
531 let mut explicit_index = variant_index.as_u32();
534 match self.variant(VariantIdx::from_u32(explicit_index)).discr {
535 ty::VariantDiscr::Relative(0) => {
539 ty::VariantDiscr::Relative(distance) => {
540 explicit_index -= distance;
542 ty::VariantDiscr::Explicit(did) => {
543 expr_did = Some(did);
548 (expr_did, variant_index.as_u32() - explicit_index)
551 pub fn destructor(self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
552 tcx.adt_destructor(self.did())
555 /// Returns a list of types such that `Self: Sized` if and only
556 /// if that type is `Sized`, or `TyErr` if this type is recursive.
558 /// Oddly enough, checking that the sized-constraint is `Sized` is
559 /// actually more expressive than checking all members:
560 /// the `Sized` trait is inductive, so an associated type that references
561 /// `Self` would prevent its containing ADT from being `Sized`.
563 /// Due to normalization being eager, this applies even if
564 /// the associated type is behind a pointer (e.g., issue #31299).
565 pub fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> ty::EarlyBinder<&'tcx [Ty<'tcx>]> {
566 ty::EarlyBinder(tcx.adt_sized_constraint(self.did()).0)
570 #[derive(Clone, Copy, Debug)]
571 #[derive(HashStable)]
572 pub enum Representability {