crates/hir_ty/src/lib.rs

   1 //! The type system. We currently use this to infer types for completion, hover
   2 //! information and various assists.
   3 #[allow(unused)]
   4 macro_rules! eprintln {
   5     ($($tt:tt)*) => { stdx::eprintln!($($tt)*) };
   6 }
   7
   8 mod autoderef;
   9 pub mod primitive;
  10 pub mod traits;
  11 pub mod method_resolution;
  12 mod op;
  13 mod lower;
  14 pub(crate) mod infer;
  15 pub(crate) mod utils;
  16 mod chalk_cast;
  17 mod chalk_ext;
  18 mod builder;
  19 mod walk;
  20 mod types;
  21
  22 pub mod display;
  23 pub mod db;
  24 pub mod diagnostics;
  25
  26 #[cfg(test)]
  27 mod tests;
  28 #[cfg(test)]
  29 mod test_db;
  30
  31 use std::sync::Arc;
  32
  33 use itertools::Itertools;
  34
  35 use base_db::salsa;
  36 use hir_def::{
  37     expr::ExprId, type_ref::Rawness, AssocContainerId, FunctionId, GenericDefId, HasModule,
  38     LifetimeParamId, Lookup, TraitId, TypeAliasId, TypeParamId,
  39 };
  40
  41 use crate::{db::HirDatabase, display::HirDisplay, utils::generics};
  42
  43 pub use autoderef::autoderef;
  44 pub use builder::TyBuilder;
  45 pub use chalk_ext::{ProjectionTyExt, TyExt};
  46 pub use infer::{could_unify, InferenceResult, InferenceVar};
  47 pub use lower::{
  48     associated_type_shorthand_candidates, callable_item_sig, CallableDefId, ImplTraitLoweringMode,
  49     TyDefId, TyLoweringContext, ValueTyDefId,
  50 };
  51 pub use traits::{chalk::Interner, TraitEnvironment};
  52 pub use types::*;
  53 pub use walk::TypeWalk;
  54
  55 pub use chalk_ir::{
  56     cast::Cast, AdtId, BoundVar, DebruijnIndex, Mutability, Safety, Scalar, TyVariableKind,
  57 };
  58
  59 pub type ForeignDefId = chalk_ir::ForeignDefId<Interner>;
  60 pub type AssocTypeId = chalk_ir::AssocTypeId<Interner>;
  61 pub type FnDefId = chalk_ir::FnDefId<Interner>;
  62 pub type ClosureId = chalk_ir::ClosureId<Interner>;
  63 pub type OpaqueTyId = chalk_ir::OpaqueTyId<Interner>;
  64 pub type PlaceholderIndex = chalk_ir::PlaceholderIndex;
  65
  66 pub type VariableKind = chalk_ir::VariableKind<Interner>;
  67 pub type VariableKinds = chalk_ir::VariableKinds<Interner>;
  68 pub type CanonicalVarKinds = chalk_ir::CanonicalVarKinds<Interner>;
  69
  70 pub type Lifetime = chalk_ir::Lifetime<Interner>;
  71 pub type LifetimeData = chalk_ir::LifetimeData<Interner>;
  72 pub type LifetimeOutlives = chalk_ir::LifetimeOutlives<Interner>;
  73
  74 pub type ChalkTraitId = chalk_ir::TraitId<Interner>;
  75
  76 pub type FnSig = chalk_ir::FnSig<Interner>;
  77
  78 impl Substitution {
  79     pub fn prefix(&self, n: usize) -> Substitution {
  80         Substitution::intern(self.interned()[..std::cmp::min(self.len(&Interner), n)].into())
  81     }
  82
  83     pub fn suffix(&self, n: usize) -> Substitution {
  84         Substitution::intern(
  85             self.interned()[self.len(&Interner) - std::cmp::min(self.len(&Interner), n)..].into(),
  86         )
  87     }
  88 }
  89
  90 /// Return an index of a parameter in the generic type parameter list by it's id.
  91 pub fn param_idx(db: &dyn HirDatabase, id: TypeParamId) -> Option<usize> {
  92     generics(db.upcast(), id.parent).param_idx(id)
  93 }
  94
  95 impl<T> Binders<T> {
  96     pub fn wrap_empty(value: T) -> Self
  97     where
  98         T: TypeWalk,
  99     {
 100         Binders::empty(&Interner, value.shifted_in_from(DebruijnIndex::ONE))
 101     }
 102 }
 103
 104 impl<T: TypeWalk> Binders<T> {
 105     /// Substitutes all variables.
 106     pub fn substitute(self, interner: &Interner, subst: &Substitution) -> T {
 107         let (value, binders) = self.into_value_and_skipped_binders();
 108         assert_eq!(subst.len(interner), binders.len(interner));
 109         value.subst_bound_vars(subst)
 110     }
 111 }
 112
 113 pub fn make_only_type_binders<T>(num_vars: usize, value: T) -> Binders<T> {
 114     Binders::new(
 115         VariableKinds::from_iter(
 116             &Interner,
 117             std::iter::repeat(chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General))
 118                 .take(num_vars),
 119         ),
 120         value,
 121     )
 122 }
 123
 124 impl TraitRef {
 125     pub fn self_type_parameter(&self, interner: &Interner) -> &Ty {
 126         &self.substitution.at(interner, 0).assert_ty_ref(interner)
 127     }
 128
 129     pub fn hir_trait_id(&self) -> TraitId {
 130         from_chalk_trait_id(self.trait_id)
 131     }
 132 }
 133
 134 impl WhereClause {
 135     pub fn is_implemented(&self) -> bool {
 136         matches!(self, WhereClause::Implemented(_))
 137     }
 138
 139     pub fn trait_ref(&self, db: &dyn HirDatabase) -> Option<TraitRef> {
 140         match self {
 141             WhereClause::Implemented(tr) => Some(tr.clone()),
 142             WhereClause::AliasEq(AliasEq { alias: AliasTy::Projection(proj), .. }) => {
 143                 Some(proj.trait_ref(db))
 144             }
 145             WhereClause::AliasEq(_) => None,
 146         }
 147     }
 148 }
 149
 150 impl<T> Canonical<T> {
 151     pub fn new(value: T, kinds: impl IntoIterator<Item = TyVariableKind>) -> Self {
 152         let kinds = kinds.into_iter().map(|tk| {
 153             chalk_ir::CanonicalVarKind::new(
 154                 chalk_ir::VariableKind::Ty(tk),
 155                 chalk_ir::UniverseIndex::ROOT,
 156             )
 157         });
 158         Self { value, binders: chalk_ir::CanonicalVarKinds::from_iter(&Interner, kinds) }
 159     }
 160 }
 161
 162 /// A function signature as seen by type inference: Several parameter types and
 163 /// one return type.
 164 #[derive(Clone, PartialEq, Eq, Debug)]
 165 pub struct CallableSig {
 166     params_and_return: Arc<[Ty]>,
 167     is_varargs: bool,
 168 }
 169
 170 /// A polymorphic function signature.
 171 pub type PolyFnSig = Binders<CallableSig>;
 172
 173 impl CallableSig {
 174     pub fn from_params_and_return(mut params: Vec<Ty>, ret: Ty, is_varargs: bool) -> CallableSig {
 175         params.push(ret);
 176         CallableSig { params_and_return: params.into(), is_varargs }
 177     }
 178
 179     pub fn from_fn_ptr(fn_ptr: &FnPointer) -> CallableSig {
 180         CallableSig {
 181             // FIXME: what to do about lifetime params? -> return PolyFnSig
 182             params_and_return: fn_ptr
 183                 .substs
 184                 .clone()
 185                 .shifted_out_to(DebruijnIndex::ONE)
 186                 .expect("unexpected lifetime vars in fn ptr")
 187                 .interned()
 188                 .iter()
 189                 .map(|arg| arg.assert_ty_ref(&Interner).clone())
 190                 .collect(),
 191             is_varargs: fn_ptr.sig.variadic,
 192         }
 193     }
 194
 195     pub fn params(&self) -> &[Ty] {
 196         &self.params_and_return[0..self.params_and_return.len() - 1]
 197     }
 198
 199     pub fn ret(&self) -> &Ty {
 200         &self.params_and_return[self.params_and_return.len() - 1]
 201     }
 202 }
 203
 204 impl Ty {
 205     pub fn as_reference(&self) -> Option<(&Ty, Mutability)> {
 206         match self.kind(&Interner) {
 207             TyKind::Ref(mutability, ty) => Some((ty, *mutability)),
 208             _ => None,
 209         }
 210     }
 211
 212     pub fn as_reference_or_ptr(&self) -> Option<(&Ty, Rawness, Mutability)> {
 213         match self.kind(&Interner) {
 214             TyKind::Ref(mutability, ty) => Some((ty, Rawness::Ref, *mutability)),
 215             TyKind::Raw(mutability, ty) => Some((ty, Rawness::RawPtr, *mutability)),
 216             _ => None,
 217         }
 218     }
 219
 220     pub fn strip_references(&self) -> &Ty {
 221         let mut t: &Ty = self;
 222
 223         while let TyKind::Ref(_mutability, ty) = t.kind(&Interner) {
 224             t = ty;
 225         }
 226
 227         t
 228     }
 229
 230     pub fn as_adt(&self) -> Option<(hir_def::AdtId, &Substitution)> {
 231         match self.kind(&Interner) {
 232             TyKind::Adt(AdtId(adt), parameters) => Some((*adt, parameters)),
 233             _ => None,
 234         }
 235     }
 236
 237     pub fn as_tuple(&self) -> Option<&Substitution> {
 238         match self.kind(&Interner) {
 239             TyKind::Tuple(_, substs) => Some(substs),
 240             _ => None,
 241         }
 242     }
 243
 244     pub fn as_generic_def(&self, db: &dyn HirDatabase) -> Option<GenericDefId> {
 245         match *self.kind(&Interner) {
 246             TyKind::Adt(AdtId(adt), ..) => Some(adt.into()),
 247             TyKind::FnDef(callable, ..) => {
 248                 Some(db.lookup_intern_callable_def(callable.into()).into())
 249             }
 250             TyKind::AssociatedType(type_alias, ..) => Some(from_assoc_type_id(type_alias).into()),
 251             TyKind::Foreign(type_alias, ..) => Some(from_foreign_def_id(type_alias).into()),
 252             _ => None,
 253         }
 254     }
 255
 256     pub fn is_never(&self) -> bool {
 257         matches!(self.kind(&Interner), TyKind::Never)
 258     }
 259
 260     pub fn is_unknown(&self) -> bool {
 261         matches!(self.kind(&Interner), TyKind::Error)
 262     }
 263
 264     pub fn equals_ctor(&self, other: &Ty) -> bool {
 265         match (self.kind(&Interner), other.kind(&Interner)) {
 266             (TyKind::Adt(adt, ..), TyKind::Adt(adt2, ..)) => adt == adt2,
 267             (TyKind::Slice(_), TyKind::Slice(_)) | (TyKind::Array(_), TyKind::Array(_)) => true,
 268             (TyKind::FnDef(def_id, ..), TyKind::FnDef(def_id2, ..)) => def_id == def_id2,
 269             (TyKind::OpaqueType(ty_id, ..), TyKind::OpaqueType(ty_id2, ..)) => ty_id == ty_id2,
 270             (TyKind::AssociatedType(ty_id, ..), TyKind::AssociatedType(ty_id2, ..)) => {
 271                 ty_id == ty_id2
 272             }
 273             (TyKind::Foreign(ty_id, ..), TyKind::Foreign(ty_id2, ..)) => ty_id == ty_id2,
 274             (TyKind::Closure(id1, _), TyKind::Closure(id2, _)) => id1 == id2,
 275             (TyKind::Ref(mutability, ..), TyKind::Ref(mutability2, ..))
 276             | (TyKind::Raw(mutability, ..), TyKind::Raw(mutability2, ..)) => {
 277                 mutability == mutability2
 278             }
 279             (
 280                 TyKind::Function(FnPointer { num_args, sig, .. }),
 281                 TyKind::Function(FnPointer { num_args: num_args2, sig: sig2, .. }),
 282             ) => num_args == num_args2 && sig == sig2,
 283             (TyKind::Tuple(cardinality, _), TyKind::Tuple(cardinality2, _)) => {
 284                 cardinality == cardinality2
 285             }
 286             (TyKind::Str, TyKind::Str) | (TyKind::Never, TyKind::Never) => true,
 287             (TyKind::Scalar(scalar), TyKind::Scalar(scalar2)) => scalar == scalar2,
 288             _ => false,
 289         }
 290     }
 291
 292     /// If this is a `dyn Trait` type, this returns the `Trait` part.
 293     fn dyn_trait_ref(&self) -> Option<&TraitRef> {
 294         match self.kind(&Interner) {
 295             TyKind::Dyn(dyn_ty) => dyn_ty.bounds.skip_binders().interned().get(0).and_then(|b| {
 296                 match b.skip_binders() {
 297                     WhereClause::Implemented(trait_ref) => Some(trait_ref),
 298                     _ => None,
 299                 }
 300             }),
 301             _ => None,
 302         }
 303     }
 304
 305     /// If this is a `dyn Trait`, returns that trait.
 306     pub fn dyn_trait(&self) -> Option<TraitId> {
 307         self.dyn_trait_ref().map(|it| it.trait_id).map(from_chalk_trait_id)
 308     }
 309
 310     fn builtin_deref(&self) -> Option<Ty> {
 311         match self.kind(&Interner) {
 312             TyKind::Ref(.., ty) => Some(ty.clone()),
 313             TyKind::Raw(.., ty) => Some(ty.clone()),
 314             _ => None,
 315         }
 316     }
 317
 318     pub fn callable_def(&self, db: &dyn HirDatabase) -> Option<CallableDefId> {
 319         match self.kind(&Interner) {
 320             &TyKind::FnDef(def, ..) => Some(db.lookup_intern_callable_def(def.into())),
 321             _ => None,
 322         }
 323     }
 324
 325     pub fn as_fn_def(&self, db: &dyn HirDatabase) -> Option<FunctionId> {
 326         if let Some(CallableDefId::FunctionId(func)) = self.callable_def(db) {
 327             Some(func)
 328         } else {
 329             None
 330         }
 331     }
 332
 333     pub fn callable_sig(&self, db: &dyn HirDatabase) -> Option<CallableSig> {
 334         match self.kind(&Interner) {
 335             TyKind::Function(fn_ptr) => Some(CallableSig::from_fn_ptr(fn_ptr)),
 336             TyKind::FnDef(def, parameters) => {
 337                 let callable_def = db.lookup_intern_callable_def((*def).into());
 338                 let sig = db.callable_item_signature(callable_def);
 339                 Some(sig.substitute(&Interner, &parameters))
 340             }
 341             TyKind::Closure(.., substs) => {
 342                 let sig_param = substs.at(&Interner, 0).assert_ty_ref(&Interner);
 343                 sig_param.callable_sig(db)
 344             }
 345             _ => None,
 346         }
 347     }
 348
 349     /// Returns the type parameters of this type if it has some (i.e. is an ADT
 350     /// or function); so if `self` is `Option<u32>`, this returns the `u32`.
 351     pub fn substs(&self) -> Option<&Substitution> {
 352         match self.kind(&Interner) {
 353             TyKind::Adt(_, substs)
 354             | TyKind::FnDef(_, substs)
 355             | TyKind::Function(FnPointer { substs, .. })
 356             | TyKind::Tuple(_, substs)
 357             | TyKind::OpaqueType(_, substs)
 358             | TyKind::AssociatedType(_, substs)
 359             | TyKind::Closure(.., substs) => Some(substs),
 360             _ => None,
 361         }
 362     }
 363
 364     fn substs_mut(&mut self) -> Option<&mut Substitution> {
 365         match self.interned_mut() {
 366             TyKind::Adt(_, substs)
 367             | TyKind::FnDef(_, substs)
 368             | TyKind::Function(FnPointer { substs, .. })
 369             | TyKind::Tuple(_, substs)
 370             | TyKind::OpaqueType(_, substs)
 371             | TyKind::AssociatedType(_, substs)
 372             | TyKind::Closure(.., substs) => Some(substs),
 373             _ => None,
 374         }
 375     }
 376
 377     pub fn impl_trait_bounds(&self, db: &dyn HirDatabase) -> Option<Vec<QuantifiedWhereClause>> {
 378         match self.kind(&Interner) {
 379             TyKind::OpaqueType(opaque_ty_id, ..) => {
 380                 match db.lookup_intern_impl_trait_id((*opaque_ty_id).into()) {
 381                     ImplTraitId::AsyncBlockTypeImplTrait(def, _expr) => {
 382                         let krate = def.module(db.upcast()).krate();
 383                         if let Some(future_trait) = db
 384                             .lang_item(krate, "future_trait".into())
 385                             .and_then(|item| item.as_trait())
 386                         {
 387                             // This is only used by type walking.
 388                             // Parameters will be walked outside, and projection predicate is not used.
 389                             // So just provide the Future trait.
 390                             let impl_bound = Binders::empty(
 391                                 &Interner,
 392                                 WhereClause::Implemented(TraitRef {
 393                                     trait_id: to_chalk_trait_id(future_trait),
 394                                     substitution: Substitution::empty(&Interner),
 395                                 }),
 396                             );
 397                             Some(vec![impl_bound])
 398                         } else {
 399                             None
 400                         }
 401                     }
 402                     ImplTraitId::ReturnTypeImplTrait(..) => None,
 403                 }
 404             }
 405             TyKind::Alias(AliasTy::Opaque(opaque_ty)) => {
 406                 let predicates = match db.lookup_intern_impl_trait_id(opaque_ty.opaque_ty_id.into())
 407                 {
 408                     ImplTraitId::ReturnTypeImplTrait(func, idx) => {
 409                         db.return_type_impl_traits(func).map(|it| {
 410                             let data = (*it)
 411                                 .as_ref()
 412                                 .map(|rpit| rpit.impl_traits[idx as usize].bounds.clone());
 413                             data.substitute(&Interner, &opaque_ty.substitution)
 414                         })
 415                     }
 416                     // It always has an parameter for Future::Output type.
 417                     ImplTraitId::AsyncBlockTypeImplTrait(..) => unreachable!(),
 418                 };
 419
 420                 predicates.map(|it| it.into_value_and_skipped_binders().0)
 421             }
 422             TyKind::Placeholder(idx) => {
 423                 let id = from_placeholder_idx(db, *idx);
 424                 let generic_params = db.generic_params(id.parent);
 425                 let param_data = &generic_params.types[id.local_id];
 426                 match param_data.provenance {
 427                     hir_def::generics::TypeParamProvenance::ArgumentImplTrait => {
 428                         let substs = TyBuilder::type_params_subst(db, id.parent);
 429                         let predicates = db
 430                             .generic_predicates(id.parent)
 431                             .into_iter()
 432                             .map(|pred| pred.clone().substitute(&Interner, &substs))
 433                             .filter(|wc| match &wc.skip_binders() {
 434                                 WhereClause::Implemented(tr) => {
 435                                     tr.self_type_parameter(&Interner) == self
 436                                 }
 437                                 WhereClause::AliasEq(AliasEq {
 438                                     alias: AliasTy::Projection(proj),
 439                                     ty: _,
 440                                 }) => proj.self_type_parameter(&Interner) == self,
 441                                 _ => false,
 442                             })
 443                             .collect_vec();
 444
 445                         Some(predicates)
 446                     }
 447                     _ => None,
 448                 }
 449             }
 450             _ => None,
 451         }
 452     }
 453
 454     pub fn associated_type_parent_trait(&self, db: &dyn HirDatabase) -> Option<TraitId> {
 455         match self.kind(&Interner) {
 456             TyKind::AssociatedType(id, ..) => {
 457                 match from_assoc_type_id(*id).lookup(db.upcast()).container {
 458                     AssocContainerId::TraitId(trait_id) => Some(trait_id),
 459                     _ => None,
 460                 }
 461             }
 462             TyKind::Alias(AliasTy::Projection(projection_ty)) => {
 463                 match from_assoc_type_id(projection_ty.associated_ty_id)
 464                     .lookup(db.upcast())
 465                     .container
 466                 {
 467                     AssocContainerId::TraitId(trait_id) => Some(trait_id),
 468                     _ => None,
 469                 }
 470             }
 471             _ => None,
 472         }
 473     }
 474 }
 475
 476 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
 477 pub enum ImplTraitId {
 478     ReturnTypeImplTrait(hir_def::FunctionId, u16),
 479     AsyncBlockTypeImplTrait(hir_def::DefWithBodyId, ExprId),
 480 }
 481
 482 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 483 pub struct ReturnTypeImplTraits {
 484     pub(crate) impl_traits: Vec<ReturnTypeImplTrait>,
 485 }
 486
 487 #[derive(Clone, PartialEq, Eq, Debug, Hash)]
 488 pub(crate) struct ReturnTypeImplTrait {
 489     pub(crate) bounds: Binders<Vec<QuantifiedWhereClause>>,
 490 }
 491
 492 pub fn to_foreign_def_id(id: TypeAliasId) -> ForeignDefId {
 493     chalk_ir::ForeignDefId(salsa::InternKey::as_intern_id(&id))
 494 }
 495
 496 pub fn from_foreign_def_id(id: ForeignDefId) -> TypeAliasId {
 497     salsa::InternKey::from_intern_id(id.0)
 498 }
 499
 500 pub fn to_assoc_type_id(id: TypeAliasId) -> AssocTypeId {
 501     chalk_ir::AssocTypeId(salsa::InternKey::as_intern_id(&id))
 502 }
 503
 504 pub fn from_assoc_type_id(id: AssocTypeId) -> TypeAliasId {
 505     salsa::InternKey::from_intern_id(id.0)
 506 }
 507
 508 pub fn from_placeholder_idx(db: &dyn HirDatabase, idx: PlaceholderIndex) -> TypeParamId {
 509     assert_eq!(idx.ui, chalk_ir::UniverseIndex::ROOT);
 510     let interned_id = salsa::InternKey::from_intern_id(salsa::InternId::from(idx.idx));
 511     db.lookup_intern_type_param_id(interned_id)
 512 }
 513
 514 pub fn to_placeholder_idx(db: &dyn HirDatabase, id: TypeParamId) -> PlaceholderIndex {
 515     let interned_id = db.intern_type_param_id(id);
 516     PlaceholderIndex {
 517         ui: chalk_ir::UniverseIndex::ROOT,
 518         idx: salsa::InternKey::as_intern_id(&interned_id).as_usize(),
 519     }
 520 }
 521
 522 pub fn lt_from_placeholder_idx(db: &dyn HirDatabase, idx: PlaceholderIndex) -> LifetimeParamId {
 523     assert_eq!(idx.ui, chalk_ir::UniverseIndex::ROOT);
 524     let interned_id = salsa::InternKey::from_intern_id(salsa::InternId::from(idx.idx));
 525     db.lookup_intern_lifetime_param_id(interned_id)
 526 }
 527
 528 pub fn to_chalk_trait_id(id: TraitId) -> ChalkTraitId {
 529     chalk_ir::TraitId(salsa::InternKey::as_intern_id(&id))
 530 }
 531
 532 pub fn from_chalk_trait_id(id: ChalkTraitId) -> TraitId {
 533     salsa::InternKey::from_intern_id(id.0)
 534 }