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,
30 #[derive(HashStable, TyEncodable, TyDecodable)]
31 pub struct AdtFlags: u32 {
32 const NO_ADT_FLAGS = 0;
33 /// Indicates whether the ADT is an enum.
34 const IS_ENUM = 1 << 0;
35 /// Indicates whether the ADT is a union.
36 const IS_UNION = 1 << 1;
37 /// Indicates whether the ADT is a struct.
38 const IS_STRUCT = 1 << 2;
39 /// Indicates whether the ADT is a struct and has a constructor.
40 const HAS_CTOR = 1 << 3;
41 /// Indicates whether the type is `PhantomData`.
42 const IS_PHANTOM_DATA = 1 << 4;
43 /// Indicates whether the type has a `#[fundamental]` attribute.
44 const IS_FUNDAMENTAL = 1 << 5;
45 /// Indicates whether the type is `Box`.
46 const IS_BOX = 1 << 6;
47 /// Indicates whether the type is `ManuallyDrop`.
48 const IS_MANUALLY_DROP = 1 << 7;
49 /// Indicates whether the variant list of this ADT is `#[non_exhaustive]`.
50 /// (i.e., this flag is never set unless this ADT is an enum).
51 const IS_VARIANT_LIST_NON_EXHAUSTIVE = 1 << 8;
52 /// Indicates whether the type is `UnsafeCell`.
53 const IS_UNSAFE_CELL = 1 << 9;
57 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
59 /// These are all interned (by `alloc_adt_def`) into the global arena.
61 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
62 /// This is slightly wrong because `union`s are not ADTs.
63 /// Moreover, Rust only allows recursive data types through indirection.
65 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
69 /// It may seem impossible to represent recursive types using [`Ty`],
70 /// since [`TyKind::Adt`] includes [`AdtDef`], which includes its fields,
71 /// creating a cycle. However, `AdtDef` does not actually include the *types*
72 /// of its fields; it includes just their [`DefId`]s.
74 /// [`TyKind::Adt`]: ty::TyKind::Adt
76 /// For example, the following type:
79 /// struct S { x: Box<S> }
82 /// is essentially represented with [`Ty`] as the following pseudocode:
84 /// ```ignore (illustrative)
88 /// where `x` here represents the `DefId` of `S.x`. Then, the `DefId`
89 /// can be used with [`TyCtxt::type_of()`] to get the type of the field.
90 #[derive(TyEncodable, TyDecodable)]
91 pub struct AdtDefData {
92 /// The `DefId` of the struct, enum or union item.
94 /// Variants of the ADT. If this is a struct or union, then there will be a single variant.
95 variants: IndexVec<VariantIdx, VariantDef>,
96 /// Flags of the ADT (e.g., is this a struct? is this non-exhaustive?).
98 /// Repr options provided by the user.
102 impl PartialOrd for AdtDefData {
103 fn partial_cmp(&self, other: &AdtDefData) -> Option<Ordering> {
104 Some(self.cmp(&other))
108 /// There should be only one AdtDef for each `did`, therefore
109 /// it is fine to implement `Ord` only based on `did`.
110 impl Ord for AdtDefData {
111 fn cmp(&self, other: &AdtDefData) -> Ordering {
112 self.did.cmp(&other.did)
116 /// There should be only one AdtDef for each `did`, therefore
117 /// it is fine to implement `PartialEq` only based on `did`.
118 impl PartialEq for AdtDefData {
120 fn eq(&self, other: &Self) -> bool {
121 self.did == other.did
125 impl Eq for AdtDefData {}
127 /// There should be only one AdtDef for each `did`, therefore
128 /// it is fine to implement `Hash` only based on `did`.
129 impl Hash for AdtDefData {
131 fn hash<H: Hasher>(&self, s: &mut H) {
136 impl<'a> HashStable<StableHashingContext<'a>> for AdtDefData {
137 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
139 static CACHE: RefCell<FxHashMap<(usize, HashingControls), Fingerprint>> = Default::default();
142 let hash: Fingerprint = CACHE.with(|cache| {
143 let addr = self as *const AdtDefData as usize;
144 let hashing_controls = hcx.hashing_controls();
145 *cache.borrow_mut().entry((addr, hashing_controls)).or_insert_with(|| {
146 let ty::AdtDefData { did, ref variants, ref flags, ref repr } = *self;
148 let mut hasher = StableHasher::new();
149 did.hash_stable(hcx, &mut hasher);
150 variants.hash_stable(hcx, &mut hasher);
151 flags.hash_stable(hcx, &mut hasher);
152 repr.hash_stable(hcx, &mut hasher);
158 hash.hash_stable(hcx, hasher);
162 #[derive(Copy, Clone, PartialEq, Eq, Hash, Ord, PartialOrd, HashStable)]
163 #[rustc_pass_by_value]
164 pub struct AdtDef<'tcx>(pub Interned<'tcx, AdtDefData>);
166 impl<'tcx> AdtDef<'tcx> {
168 pub fn did(self) -> DefId {
173 pub fn variants(self) -> &'tcx IndexVec<VariantIdx, VariantDef> {
178 pub fn variant(self, idx: VariantIdx) -> &'tcx VariantDef {
179 &self.0.0.variants[idx]
183 pub fn flags(self) -> AdtFlags {
188 pub fn repr(self) -> ReprOptions {
193 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, TyEncodable, TyDecodable)]
200 impl Into<DataTypeKind> for AdtKind {
201 fn into(self) -> DataTypeKind {
203 AdtKind::Struct => DataTypeKind::Struct,
204 AdtKind::Union => DataTypeKind::Union,
205 AdtKind::Enum => DataTypeKind::Enum,
211 /// Creates a new `AdtDefData`.
216 variants: IndexVec<VariantIdx, VariantDef>,
219 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
220 let mut flags = AdtFlags::NO_ADT_FLAGS;
222 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
223 debug!("found non-exhaustive variant list for {:?}", did);
224 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
227 flags |= match kind {
228 AdtKind::Enum => AdtFlags::IS_ENUM,
229 AdtKind::Union => AdtFlags::IS_UNION,
230 AdtKind::Struct => AdtFlags::IS_STRUCT,
233 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
234 flags |= AdtFlags::HAS_CTOR;
237 if tcx.has_attr(did, sym::fundamental) {
238 flags |= AdtFlags::IS_FUNDAMENTAL;
240 if Some(did) == tcx.lang_items().phantom_data() {
241 flags |= AdtFlags::IS_PHANTOM_DATA;
243 if Some(did) == tcx.lang_items().owned_box() {
244 flags |= AdtFlags::IS_BOX;
246 if Some(did) == tcx.lang_items().manually_drop() {
247 flags |= AdtFlags::IS_MANUALLY_DROP;
249 if Some(did) == tcx.lang_items().unsafe_cell_type() {
250 flags |= AdtFlags::IS_UNSAFE_CELL;
253 AdtDefData { did, variants, flags, repr }
257 impl<'tcx> AdtDef<'tcx> {
258 /// Returns `true` if this is a struct.
260 pub fn is_struct(self) -> bool {
261 self.flags().contains(AdtFlags::IS_STRUCT)
264 /// Returns `true` if this is a union.
266 pub fn is_union(self) -> bool {
267 self.flags().contains(AdtFlags::IS_UNION)
270 /// Returns `true` if this is an enum.
272 pub fn is_enum(self) -> bool {
273 self.flags().contains(AdtFlags::IS_ENUM)
276 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
278 pub fn is_variant_list_non_exhaustive(self) -> bool {
279 self.flags().contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
282 /// Returns the kind of the ADT.
284 pub fn adt_kind(self) -> AdtKind {
287 } else if self.is_union() {
294 /// Returns a description of this abstract data type.
295 pub fn descr(self) -> &'static str {
296 match self.adt_kind() {
297 AdtKind::Struct => "struct",
298 AdtKind::Union => "union",
299 AdtKind::Enum => "enum",
303 /// Returns a description of a variant of this abstract data type.
305 pub fn variant_descr(self) -> &'static str {
306 match self.adt_kind() {
307 AdtKind::Struct => "struct",
308 AdtKind::Union => "union",
309 AdtKind::Enum => "variant",
313 /// If this function returns `true`, it implies that `is_struct` must return `true`.
315 pub fn has_ctor(self) -> bool {
316 self.flags().contains(AdtFlags::HAS_CTOR)
319 /// Returns `true` if this type is `#[fundamental]` for the purposes
320 /// of coherence checking.
322 pub fn is_fundamental(self) -> bool {
323 self.flags().contains(AdtFlags::IS_FUNDAMENTAL)
326 /// Returns `true` if this is `PhantomData<T>`.
328 pub fn is_phantom_data(self) -> bool {
329 self.flags().contains(AdtFlags::IS_PHANTOM_DATA)
332 /// Returns `true` if this is `Box<T>`.
334 pub fn is_box(self) -> bool {
335 self.flags().contains(AdtFlags::IS_BOX)
338 /// Returns `true` if this is `UnsafeCell<T>`.
340 pub fn is_unsafe_cell(self) -> bool {
341 self.flags().contains(AdtFlags::IS_UNSAFE_CELL)
344 /// Returns `true` if this is `ManuallyDrop<T>`.
346 pub fn is_manually_drop(self) -> bool {
347 self.flags().contains(AdtFlags::IS_MANUALLY_DROP)
350 /// Returns `true` if this type has a destructor.
351 pub fn has_dtor(self, tcx: TyCtxt<'tcx>) -> bool {
352 self.destructor(tcx).is_some()
355 pub fn has_non_const_dtor(self, tcx: TyCtxt<'tcx>) -> bool {
356 matches!(self.destructor(tcx), Some(Destructor { constness: hir::Constness::NotConst, .. }))
359 /// Asserts this is a struct or union and returns its unique variant.
360 pub fn non_enum_variant(self) -> &'tcx VariantDef {
361 assert!(self.is_struct() || self.is_union());
362 &self.variant(VariantIdx::new(0))
366 pub fn predicates(self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
367 tcx.predicates_of(self.did())
370 /// Returns an iterator over all fields contained
373 pub fn all_fields(self) -> impl Iterator<Item = &'tcx FieldDef> + Clone {
374 self.variants().iter().flat_map(|v| v.fields.iter())
377 /// Whether the ADT lacks fields. Note that this includes uninhabited enums,
378 /// e.g., `enum Void {}` is considered payload free as well.
379 pub fn is_payloadfree(self) -> bool {
380 // Treat the ADT as not payload-free if arbitrary_enum_discriminant is used (#88621).
381 // This would disallow the following kind of enum from being casted into integer.
392 .any(|v| matches!(v.discr, VariantDiscr::Explicit(_)) && v.ctor_kind != CtorKind::Const)
396 self.variants().iter().all(|v| v.fields.is_empty())
399 /// Return a `VariantDef` given a variant id.
400 pub fn variant_with_id(self, vid: DefId) -> &'tcx VariantDef {
401 self.variants().iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
404 /// Return a `VariantDef` given a constructor id.
405 pub fn variant_with_ctor_id(self, cid: DefId) -> &'tcx VariantDef {
408 .find(|v| v.ctor_def_id == Some(cid))
409 .expect("variant_with_ctor_id: unknown variant")
412 /// Return the index of `VariantDef` given a variant id.
413 pub fn variant_index_with_id(self, vid: DefId) -> VariantIdx {
416 .find(|(_, v)| v.def_id == vid)
417 .expect("variant_index_with_id: unknown variant")
421 /// Return the index of `VariantDef` given a constructor id.
422 pub fn variant_index_with_ctor_id(self, cid: DefId) -> VariantIdx {
425 .find(|(_, v)| v.ctor_def_id == Some(cid))
426 .expect("variant_index_with_ctor_id: unknown variant")
430 pub fn variant_of_res(self, res: Res) -> &'tcx VariantDef {
432 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
433 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
434 Res::Def(DefKind::Struct, _)
435 | Res::Def(DefKind::Union, _)
436 | Res::Def(DefKind::TyAlias, _)
437 | Res::Def(DefKind::AssocTy, _)
438 | Res::SelfTyParam { .. }
439 | Res::SelfTyAlias { .. }
440 | Res::SelfCtor(..) => self.non_enum_variant(),
441 _ => bug!("unexpected res {:?} in variant_of_res", res),
446 pub fn eval_explicit_discr(self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
447 assert!(self.is_enum());
448 let param_env = tcx.param_env(expr_did);
449 let repr_type = self.repr().discr_type();
450 match tcx.const_eval_poly(expr_did) {
452 let ty = repr_type.to_ty(tcx);
453 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
454 trace!("discriminants: {} ({:?})", b, repr_type);
455 Some(Discr { val: b, ty })
457 info!("invalid enum discriminant: {:#?}", val);
458 tcx.sess.emit_err(crate::error::ConstEvalNonIntError {
459 span: tcx.def_span(expr_did),
465 let msg = match err {
466 ErrorHandled::Reported(_) | ErrorHandled::Linted => {
467 "enum discriminant evaluation failed"
469 ErrorHandled::TooGeneric => "enum discriminant depends on generics",
471 tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg);
478 pub fn discriminants(
481 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
482 assert!(self.is_enum());
483 let repr_type = self.repr().discr_type();
484 let initial = repr_type.initial_discriminant(tcx);
485 let mut prev_discr = None::<Discr<'tcx>>;
486 self.variants().iter_enumerated().map(move |(i, v)| {
487 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
488 if let VariantDiscr::Explicit(expr_did) = v.discr {
489 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
493 prev_discr = Some(discr);
500 pub fn variant_range(self) -> Range<VariantIdx> {
501 VariantIdx::new(0)..VariantIdx::new(self.variants().len())
504 /// Computes the discriminant value used by a specific variant.
505 /// Unlike `discriminants`, this is (amortized) constant-time,
506 /// only doing at most one query for evaluating an explicit
507 /// discriminant (the last one before the requested variant),
508 /// assuming there are no constant-evaluation errors there.
510 pub fn discriminant_for_variant(
513 variant_index: VariantIdx,
515 assert!(self.is_enum());
516 let (val, offset) = self.discriminant_def_for_variant(variant_index);
517 let explicit_value = val
518 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
519 .unwrap_or_else(|| self.repr().discr_type().initial_discriminant(tcx));
520 explicit_value.checked_add(tcx, offset as u128).0
523 /// Yields a `DefId` for the discriminant and an offset to add to it
524 /// Alternatively, if there is no explicit discriminant, returns the
525 /// inferred discriminant directly.
526 pub fn discriminant_def_for_variant(self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
527 assert!(!self.variants().is_empty());
528 let mut explicit_index = variant_index.as_u32();
531 match self.variant(VariantIdx::from_u32(explicit_index)).discr {
532 ty::VariantDiscr::Relative(0) => {
536 ty::VariantDiscr::Relative(distance) => {
537 explicit_index -= distance;
539 ty::VariantDiscr::Explicit(did) => {
540 expr_did = Some(did);
545 (expr_did, variant_index.as_u32() - explicit_index)
548 pub fn destructor(self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
549 tcx.adt_destructor(self.did())
552 /// Returns a list of types such that `Self: Sized` if and only
553 /// if that type is `Sized`, or `TyErr` if this type is recursive.
555 /// Oddly enough, checking that the sized-constraint is `Sized` is
556 /// actually more expressive than checking all members:
557 /// the `Sized` trait is inductive, so an associated type that references
558 /// `Self` would prevent its containing ADT from being `Sized`.
560 /// Due to normalization being eager, this applies even if
561 /// the associated type is behind a pointer (e.g., issue #31299).
562 pub fn sized_constraint(self, tcx: TyCtxt<'tcx>) -> ty::EarlyBinder<&'tcx [Ty<'tcx>]> {
563 ty::EarlyBinder(tcx.adt_sized_constraint(self.did()))
567 #[derive(Clone, Copy, Debug)]
568 #[derive(HashStable)]
569 pub enum Representability {