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::stable_hasher::{HashStable, StableHasher};
8 use rustc_errors::ErrorReported;
10 use rustc_hir::def::{CtorKind, DefKind, Res};
11 use rustc_hir::def_id::DefId;
12 use rustc_index::vec::{Idx, IndexVec};
13 use rustc_query_system::ich::StableHashingContext;
14 use rustc_serialize::{self, Encodable, Encoder};
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(Clone, HashStable, Debug)]
30 pub struct AdtSizedConstraint<'tcx>(pub &'tcx [Ty<'tcx>]);
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;
58 /// The definition of a user-defined type, e.g., a `struct`, `enum`, or `union`.
60 /// These are all interned (by `alloc_adt_def`) into the global arena.
62 /// The initialism *ADT* stands for an [*algebraic data type (ADT)*][adt].
63 /// This is slightly wrong because `union`s are not ADTs.
64 /// Moreover, Rust only allows recursive data types through indirection.
66 /// [adt]: https://en.wikipedia.org/wiki/Algebraic_data_type
70 /// It may seem impossible to represent recursive types using [`Ty`],
71 /// since [`TyKind::Adt`] includes [`AdtDef`], which includes its fields,
72 /// creating a cycle. However, `AdtDef` does not actually include the *types*
73 /// of its fields; it includes just their [`DefId`]s.
75 /// [`TyKind::Adt`]: ty::TyKind::Adt
77 /// For example, the following type:
80 /// struct S { x: Box<S> }
83 /// is essentially represented with [`Ty`] as the following pseudocode:
89 /// where `x` here represents the `DefId` of `S.x`. Then, the `DefId`
90 /// can be used with [`TyCtxt::type_of()`] to get the type of the field.
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 pub 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.
99 pub repr: ReprOptions,
102 impl PartialOrd for AdtDef {
103 fn partial_cmp(&self, other: &AdtDef) -> 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 AdtDef {
111 fn cmp(&self, other: &AdtDef) -> Ordering {
112 self.did.cmp(&other.did)
116 impl PartialEq for AdtDef {
117 // `AdtDef`s are always interned, and this is part of `TyS` equality.
119 fn eq(&self, other: &Self) -> bool {
124 impl Eq for AdtDef {}
126 impl Hash for AdtDef {
128 fn hash<H: Hasher>(&self, s: &mut H) {
129 (self as *const AdtDef).hash(s)
133 impl<S: Encoder> Encodable<S> for AdtDef {
134 fn encode(&self, s: &mut S) -> Result<(), S::Error> {
139 impl<'a> HashStable<StableHashingContext<'a>> for AdtDef {
140 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
142 static CACHE: RefCell<FxHashMap<usize, Fingerprint>> = Default::default();
145 let hash: Fingerprint = CACHE.with(|cache| {
146 let addr = self as *const AdtDef as usize;
147 *cache.borrow_mut().entry(addr).or_insert_with(|| {
148 let ty::AdtDef { did, ref variants, ref flags, ref repr } = *self;
150 let mut hasher = StableHasher::new();
151 did.hash_stable(hcx, &mut hasher);
152 variants.hash_stable(hcx, &mut hasher);
153 flags.hash_stable(hcx, &mut hasher);
154 repr.hash_stable(hcx, &mut hasher);
160 hash.hash_stable(hcx, hasher);
164 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
171 impl Into<DataTypeKind> for AdtKind {
172 fn into(self) -> DataTypeKind {
174 AdtKind::Struct => DataTypeKind::Struct,
175 AdtKind::Union => DataTypeKind::Union,
176 AdtKind::Enum => DataTypeKind::Enum,
182 /// Creates a new `AdtDef`.
187 variants: IndexVec<VariantIdx, VariantDef>,
190 debug!("AdtDef::new({:?}, {:?}, {:?}, {:?})", did, kind, variants, repr);
191 let mut flags = AdtFlags::NO_ADT_FLAGS;
193 if kind == AdtKind::Enum && tcx.has_attr(did, sym::non_exhaustive) {
194 debug!("found non-exhaustive variant list for {:?}", did);
195 flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
198 flags |= match kind {
199 AdtKind::Enum => AdtFlags::IS_ENUM,
200 AdtKind::Union => AdtFlags::IS_UNION,
201 AdtKind::Struct => AdtFlags::IS_STRUCT,
204 if kind == AdtKind::Struct && variants[VariantIdx::new(0)].ctor_def_id.is_some() {
205 flags |= AdtFlags::HAS_CTOR;
208 let attrs = tcx.get_attrs(did);
209 if tcx.sess.contains_name(&attrs, sym::fundamental) {
210 flags |= AdtFlags::IS_FUNDAMENTAL;
212 if Some(did) == tcx.lang_items().phantom_data() {
213 flags |= AdtFlags::IS_PHANTOM_DATA;
215 if Some(did) == tcx.lang_items().owned_box() {
216 flags |= AdtFlags::IS_BOX;
218 if Some(did) == tcx.lang_items().manually_drop() {
219 flags |= AdtFlags::IS_MANUALLY_DROP;
222 AdtDef { did, variants, flags, repr }
225 /// Returns `true` if this is a struct.
227 pub fn is_struct(&self) -> bool {
228 self.flags.contains(AdtFlags::IS_STRUCT)
231 /// Returns `true` if this is a union.
233 pub fn is_union(&self) -> bool {
234 self.flags.contains(AdtFlags::IS_UNION)
237 /// Returns `true` if this is an enum.
239 pub fn is_enum(&self) -> bool {
240 self.flags.contains(AdtFlags::IS_ENUM)
243 /// Returns `true` if the variant list of this ADT is `#[non_exhaustive]`.
245 pub fn is_variant_list_non_exhaustive(&self) -> bool {
246 self.flags.contains(AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE)
249 /// Returns the kind of the ADT.
251 pub fn adt_kind(&self) -> AdtKind {
254 } else if self.is_union() {
261 /// Returns a description of this abstract data type.
262 pub fn descr(&self) -> &'static str {
263 match self.adt_kind() {
264 AdtKind::Struct => "struct",
265 AdtKind::Union => "union",
266 AdtKind::Enum => "enum",
270 /// Returns a description of a variant of this abstract data type.
272 pub fn variant_descr(&self) -> &'static str {
273 match self.adt_kind() {
274 AdtKind::Struct => "struct",
275 AdtKind::Union => "union",
276 AdtKind::Enum => "variant",
280 /// If this function returns `true`, it implies that `is_struct` must return `true`.
282 pub fn has_ctor(&self) -> bool {
283 self.flags.contains(AdtFlags::HAS_CTOR)
286 /// Returns `true` if this type is `#[fundamental]` for the purposes
287 /// of coherence checking.
289 pub fn is_fundamental(&self) -> bool {
290 self.flags.contains(AdtFlags::IS_FUNDAMENTAL)
293 /// Returns `true` if this is `PhantomData<T>`.
295 pub fn is_phantom_data(&self) -> bool {
296 self.flags.contains(AdtFlags::IS_PHANTOM_DATA)
299 /// Returns `true` if this is Box<T>.
301 pub fn is_box(&self) -> bool {
302 self.flags.contains(AdtFlags::IS_BOX)
305 /// Returns `true` if this is `ManuallyDrop<T>`.
307 pub fn is_manually_drop(&self) -> bool {
308 self.flags.contains(AdtFlags::IS_MANUALLY_DROP)
311 /// Returns `true` if this type has a destructor.
312 pub fn has_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
313 self.destructor(tcx).is_some()
316 pub fn has_non_const_dtor(&self, tcx: TyCtxt<'tcx>) -> bool {
317 matches!(self.destructor(tcx), Some(Destructor { constness: hir::Constness::NotConst, .. }))
320 /// Asserts this is a struct or union and returns its unique variant.
321 pub fn non_enum_variant(&self) -> &VariantDef {
322 assert!(self.is_struct() || self.is_union());
323 &self.variants[VariantIdx::new(0)]
327 pub fn predicates(&self, tcx: TyCtxt<'tcx>) -> GenericPredicates<'tcx> {
328 tcx.predicates_of(self.did)
331 /// Returns an iterator over all fields contained
334 pub fn all_fields(&self) -> impl Iterator<Item = &FieldDef> + Clone {
335 self.variants.iter().flat_map(|v| v.fields.iter())
338 /// Whether the ADT lacks fields. Note that this includes uninhabited enums,
339 /// e.g., `enum Void {}` is considered payload free as well.
340 pub fn is_payloadfree(&self) -> bool {
341 // Treat the ADT as not payload-free if arbitrary_enum_discriminant is used (#88621).
342 // This would disallow the following kind of enum from being casted into integer.
353 .any(|v| matches!(v.discr, VariantDiscr::Explicit(_)) && v.ctor_kind != CtorKind::Const)
357 self.variants.iter().all(|v| v.fields.is_empty())
360 /// Return a `VariantDef` given a variant id.
361 pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
362 self.variants.iter().find(|v| v.def_id == vid).expect("variant_with_id: unknown variant")
365 /// Return a `VariantDef` given a constructor id.
366 pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
369 .find(|v| v.ctor_def_id == Some(cid))
370 .expect("variant_with_ctor_id: unknown variant")
373 /// Return the index of `VariantDef` given a variant id.
374 pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
377 .find(|(_, v)| v.def_id == vid)
378 .expect("variant_index_with_id: unknown variant")
382 /// Return the index of `VariantDef` given a constructor id.
383 pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
386 .find(|(_, v)| v.ctor_def_id == Some(cid))
387 .expect("variant_index_with_ctor_id: unknown variant")
391 pub fn variant_of_res(&self, res: Res) -> &VariantDef {
393 Res::Def(DefKind::Variant, vid) => self.variant_with_id(vid),
394 Res::Def(DefKind::Ctor(..), cid) => self.variant_with_ctor_id(cid),
395 Res::Def(DefKind::Struct, _)
396 | Res::Def(DefKind::Union, _)
397 | Res::Def(DefKind::TyAlias, _)
398 | Res::Def(DefKind::AssocTy, _)
400 | Res::SelfCtor(..) => self.non_enum_variant(),
401 _ => bug!("unexpected res {:?} in variant_of_res", res),
406 pub fn eval_explicit_discr(&self, tcx: TyCtxt<'tcx>, expr_did: DefId) -> Option<Discr<'tcx>> {
407 assert!(self.is_enum());
408 let param_env = tcx.param_env(expr_did);
409 let repr_type = self.repr.discr_type();
410 match tcx.const_eval_poly(expr_did) {
412 let ty = repr_type.to_ty(tcx);
413 if let Some(b) = val.try_to_bits_for_ty(tcx, param_env, ty) {
414 trace!("discriminants: {} ({:?})", b, repr_type);
415 Some(Discr { val: b, ty })
417 info!("invalid enum discriminant: {:#?}", val);
418 crate::mir::interpret::struct_error(
419 tcx.at(tcx.def_span(expr_did)),
420 "constant evaluation of enum discriminant resulted in non-integer",
427 let msg = match err {
428 ErrorHandled::Reported(ErrorReported) | ErrorHandled::Linted => {
429 "enum discriminant evaluation failed"
431 ErrorHandled::TooGeneric => "enum discriminant depends on generics",
433 tcx.sess.delay_span_bug(tcx.def_span(expr_did), msg);
440 pub fn discriminants(
443 ) -> impl Iterator<Item = (VariantIdx, Discr<'tcx>)> + Captures<'tcx> {
444 assert!(self.is_enum());
445 let repr_type = self.repr.discr_type();
446 let initial = repr_type.initial_discriminant(tcx);
447 let mut prev_discr = None::<Discr<'tcx>>;
448 self.variants.iter_enumerated().map(move |(i, v)| {
449 let mut discr = prev_discr.map_or(initial, |d| d.wrap_incr(tcx));
450 if let VariantDiscr::Explicit(expr_did) = v.discr {
451 if let Some(new_discr) = self.eval_explicit_discr(tcx, expr_did) {
455 prev_discr = Some(discr);
462 pub fn variant_range(&self) -> Range<VariantIdx> {
463 VariantIdx::new(0)..VariantIdx::new(self.variants.len())
466 /// Computes the discriminant value used by a specific variant.
467 /// Unlike `discriminants`, this is (amortized) constant-time,
468 /// only doing at most one query for evaluating an explicit
469 /// discriminant (the last one before the requested variant),
470 /// assuming there are no constant-evaluation errors there.
472 pub fn discriminant_for_variant(
475 variant_index: VariantIdx,
477 assert!(self.is_enum());
478 let (val, offset) = self.discriminant_def_for_variant(variant_index);
479 let explicit_value = val
480 .and_then(|expr_did| self.eval_explicit_discr(tcx, expr_did))
481 .unwrap_or_else(|| self.repr.discr_type().initial_discriminant(tcx));
482 explicit_value.checked_add(tcx, offset as u128).0
485 /// Yields a `DefId` for the discriminant and an offset to add to it
486 /// Alternatively, if there is no explicit discriminant, returns the
487 /// inferred discriminant directly.
488 pub fn discriminant_def_for_variant(&self, variant_index: VariantIdx) -> (Option<DefId>, u32) {
489 assert!(!self.variants.is_empty());
490 let mut explicit_index = variant_index.as_u32();
493 match self.variants[VariantIdx::from_u32(explicit_index)].discr {
494 ty::VariantDiscr::Relative(0) => {
498 ty::VariantDiscr::Relative(distance) => {
499 explicit_index -= distance;
501 ty::VariantDiscr::Explicit(did) => {
502 expr_did = Some(did);
507 (expr_did, variant_index.as_u32() - explicit_index)
510 pub fn destructor(&self, tcx: TyCtxt<'tcx>) -> Option<Destructor> {
511 tcx.adt_destructor(self.did)
514 /// Returns a list of types such that `Self: Sized` if and only
515 /// if that type is `Sized`, or `TyErr` if this type is recursive.
517 /// Oddly enough, checking that the sized-constraint is `Sized` is
518 /// actually more expressive than checking all members:
519 /// the `Sized` trait is inductive, so an associated type that references
520 /// `Self` would prevent its containing ADT from being `Sized`.
522 /// Due to normalization being eager, this applies even if
523 /// the associated type is behind a pointer (e.g., issue #31299).
524 pub fn sized_constraint(&self, tcx: TyCtxt<'tcx>) -> &'tcx [Ty<'tcx>] {
525 tcx.adt_sized_constraint(self.did).0