1 //! This module is concerned with finding methods that a given type provides.
2 //! For details about how this works in rustc, see the method lookup page in the
3 //! [rustc guide](https://rust-lang.github.io/rustc-guide/method-lookup.html)
4 //! and the corresponding code mostly in librustc_typeck/check/method/probe.rs.
5 use std::{iter, ops::ControlFlow, sync::Arc};
7 use arrayvec::ArrayVec;
8 use base_db::{CrateId, Edition};
9 use chalk_ir::{cast::Cast, Mutability, UniverseIndex};
11 lang_item::LangItemTarget, nameres::DefMap, AssocContainerId, AssocItemId, BlockId, FunctionId,
12 GenericDefId, HasModule, ImplId, Lookup, ModuleId, TraitId,
14 use hir_expand::name::Name;
15 use rustc_hash::{FxHashMap, FxHashSet};
19 consteval::{self, ConstExt},
22 primitive::{self, FloatTy, IntTy, UintTy},
24 utils::all_super_traits,
25 AdtId, Canonical, CanonicalVarKinds, DebruijnIndex, ForeignDefId, InEnvironment, Interner,
26 Scalar, Substitution, TraitEnvironment, TraitRefExt, Ty, TyBuilder, TyExt, TyKind,
29 /// This is used as a key for indexing impls.
30 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
31 pub enum TyFingerprint {
32 // These are lang item impls:
39 // These can have user-defined impls:
42 ForeignType(ForeignDefId),
43 // These only exist for trait impls
50 /// Creates a TyFingerprint for looking up an inherent impl. Only certain
51 /// types can have inherent impls: if we have some `struct S`, we can have
52 /// an `impl S`, but not `impl &S`. Hence, this will return `None` for
53 /// reference types and such.
54 pub fn for_inherent_impl(ty: &Ty) -> Option<TyFingerprint> {
55 let fp = match ty.kind(&Interner) {
56 TyKind::Str => TyFingerprint::Str,
57 TyKind::Never => TyFingerprint::Never,
58 TyKind::Slice(..) => TyFingerprint::Slice,
59 TyKind::Array(..) => TyFingerprint::Array,
60 TyKind::Scalar(scalar) => TyFingerprint::Scalar(*scalar),
61 TyKind::Adt(AdtId(adt), _) => TyFingerprint::Adt(*adt),
62 TyKind::Raw(mutability, ..) => TyFingerprint::RawPtr(*mutability),
63 TyKind::Foreign(alias_id, ..) => TyFingerprint::ForeignType(*alias_id),
64 TyKind::Dyn(_) => ty.dyn_trait().map(TyFingerprint::Dyn)?,
70 /// Creates a TyFingerprint for looking up a trait impl.
71 pub fn for_trait_impl(ty: &Ty) -> Option<TyFingerprint> {
72 let fp = match ty.kind(&Interner) {
73 TyKind::Str => TyFingerprint::Str,
74 TyKind::Never => TyFingerprint::Never,
75 TyKind::Slice(..) => TyFingerprint::Slice,
76 TyKind::Array(..) => TyFingerprint::Array,
77 TyKind::Scalar(scalar) => TyFingerprint::Scalar(*scalar),
78 TyKind::Adt(AdtId(adt), _) => TyFingerprint::Adt(*adt),
79 TyKind::Raw(mutability, ..) => TyFingerprint::RawPtr(*mutability),
80 TyKind::Foreign(alias_id, ..) => TyFingerprint::ForeignType(*alias_id),
81 TyKind::Dyn(_) => ty.dyn_trait().map(TyFingerprint::Dyn)?,
82 TyKind::Ref(_, _, ty) => return TyFingerprint::for_trait_impl(ty),
83 TyKind::Tuple(_, subst) => {
84 let first_ty = subst.interned().get(0).map(|arg| arg.assert_ty_ref(&Interner));
86 Some(ty) => return TyFingerprint::for_trait_impl(ty),
87 None => TyFingerprint::Unit,
90 TyKind::AssociatedType(_, _)
91 | TyKind::OpaqueType(_, _)
93 | TyKind::Closure(_, _)
94 | TyKind::Generator(..)
95 | TyKind::GeneratorWitness(..) => TyFingerprint::Unnameable,
96 TyKind::Function(fn_ptr) => {
97 TyFingerprint::Function(fn_ptr.substitution.0.len(&Interner) as u32)
100 | TyKind::Placeholder(_)
101 | TyKind::BoundVar(_)
102 | TyKind::InferenceVar(_, _)
103 | TyKind::Error => return None,
109 pub(crate) const ALL_INT_FPS: [TyFingerprint; 12] = [
110 TyFingerprint::Scalar(Scalar::Int(IntTy::I8)),
111 TyFingerprint::Scalar(Scalar::Int(IntTy::I16)),
112 TyFingerprint::Scalar(Scalar::Int(IntTy::I32)),
113 TyFingerprint::Scalar(Scalar::Int(IntTy::I64)),
114 TyFingerprint::Scalar(Scalar::Int(IntTy::I128)),
115 TyFingerprint::Scalar(Scalar::Int(IntTy::Isize)),
116 TyFingerprint::Scalar(Scalar::Uint(UintTy::U8)),
117 TyFingerprint::Scalar(Scalar::Uint(UintTy::U16)),
118 TyFingerprint::Scalar(Scalar::Uint(UintTy::U32)),
119 TyFingerprint::Scalar(Scalar::Uint(UintTy::U64)),
120 TyFingerprint::Scalar(Scalar::Uint(UintTy::U128)),
121 TyFingerprint::Scalar(Scalar::Uint(UintTy::Usize)),
124 pub(crate) const ALL_FLOAT_FPS: [TyFingerprint; 2] = [
125 TyFingerprint::Scalar(Scalar::Float(FloatTy::F32)),
126 TyFingerprint::Scalar(Scalar::Float(FloatTy::F64)),
129 /// Trait impls defined or available in some crate.
130 #[derive(Debug, Eq, PartialEq)]
131 pub struct TraitImpls {
132 // If the `Option<TyFingerprint>` is `None`, the impl may apply to any self type.
133 map: FxHashMap<TraitId, FxHashMap<Option<TyFingerprint>, Vec<ImplId>>>,
137 pub(crate) fn trait_impls_in_crate_query(db: &dyn HirDatabase, krate: CrateId) -> Arc<Self> {
138 let _p = profile::span("trait_impls_in_crate_query");
139 let mut impls = Self { map: FxHashMap::default() };
141 let crate_def_map = db.crate_def_map(krate);
142 impls.collect_def_map(db, &crate_def_map);
147 pub(crate) fn trait_impls_in_block_query(
148 db: &dyn HirDatabase,
150 ) -> Option<Arc<Self>> {
151 let _p = profile::span("trait_impls_in_block_query");
152 let mut impls = Self { map: FxHashMap::default() };
154 let block_def_map = db.block_def_map(block)?;
155 impls.collect_def_map(db, &block_def_map);
157 Some(Arc::new(impls))
160 fn collect_def_map(&mut self, db: &dyn HirDatabase, def_map: &DefMap) {
161 for (_module_id, module_data) in def_map.modules() {
162 for impl_id in module_data.scope.impls() {
163 let target_trait = match db.impl_trait(impl_id) {
164 Some(tr) => tr.skip_binders().hir_trait_id(),
167 let self_ty = db.impl_self_ty(impl_id);
168 let self_ty_fp = TyFingerprint::for_trait_impl(self_ty.skip_binders());
177 // To better support custom derives, collect impls in all unnamed const items.
178 // const _: () = { ... };
179 for konst in module_data.scope.unnamed_consts() {
180 let body = db.body(konst.into());
181 for (_, block_def_map) in body.blocks(db.upcast()) {
182 self.collect_def_map(db, &block_def_map);
188 pub(crate) fn trait_impls_in_deps_query(db: &dyn HirDatabase, krate: CrateId) -> Arc<Self> {
189 let _p = profile::span("trait_impls_in_deps_query");
190 let crate_graph = db.crate_graph();
191 let mut res = Self { map: FxHashMap::default() };
193 for krate in crate_graph.transitive_deps(krate) {
194 res.merge(&db.trait_impls_in_crate(krate));
200 fn merge(&mut self, other: &Self) {
201 for (trait_, other_map) in &other.map {
202 let map = self.map.entry(*trait_).or_default();
203 for (fp, impls) in other_map {
204 let vec = map.entry(*fp).or_default();
210 /// Queries all trait impls for the given type.
211 pub fn for_self_ty_without_blanket_impls(
214 ) -> impl Iterator<Item = ImplId> + '_ {
217 .flat_map(move |impls| impls.get(&Some(fp)).into_iter())
218 .flat_map(|it| it.iter().copied())
221 /// Queries all impls of the given trait.
222 pub fn for_trait(&self, trait_: TraitId) -> impl Iterator<Item = ImplId> + '_ {
226 .flat_map(|map| map.values().flat_map(|v| v.iter().copied()))
229 /// Queries all impls of `trait_` that may apply to `self_ty`.
230 pub fn for_trait_and_self_ty(
233 self_ty: TyFingerprint,
234 ) -> impl Iterator<Item = ImplId> + '_ {
238 .flat_map(move |map| map.get(&None).into_iter().chain(map.get(&Some(self_ty))))
239 .flat_map(|v| v.iter().copied())
242 pub fn all_impls(&self) -> impl Iterator<Item = ImplId> + '_ {
243 self.map.values().flat_map(|map| map.values().flat_map(|v| v.iter().copied()))
247 /// Inherent impls defined in some crate.
249 /// Inherent impls can only be defined in the crate that also defines the self type of the impl
250 /// (note that some primitives are considered to be defined by both libcore and liballoc).
252 /// This makes inherent impl lookup easier than trait impl lookup since we only have to consider a
254 #[derive(Debug, Eq, PartialEq)]
255 pub struct InherentImpls {
256 map: FxHashMap<TyFingerprint, Vec<ImplId>>,
260 pub(crate) fn inherent_impls_in_crate_query(db: &dyn HirDatabase, krate: CrateId) -> Arc<Self> {
261 let mut impls = Self { map: FxHashMap::default() };
263 let crate_def_map = db.crate_def_map(krate);
264 impls.collect_def_map(db, &crate_def_map);
266 return Arc::new(impls);
269 pub(crate) fn inherent_impls_in_block_query(
270 db: &dyn HirDatabase,
272 ) -> Option<Arc<Self>> {
273 let mut impls = Self { map: FxHashMap::default() };
274 if let Some(block_def_map) = db.block_def_map(block) {
275 impls.collect_def_map(db, &block_def_map);
276 return Some(Arc::new(impls));
281 fn collect_def_map(&mut self, db: &dyn HirDatabase, def_map: &DefMap) {
282 for (_module_id, module_data) in def_map.modules() {
283 for impl_id in module_data.scope.impls() {
284 let data = db.impl_data(impl_id);
285 if data.target_trait.is_some() {
289 let self_ty = db.impl_self_ty(impl_id);
290 let fp = TyFingerprint::for_inherent_impl(self_ty.skip_binders());
291 if let Some(fp) = fp {
292 self.map.entry(fp).or_default().push(impl_id);
294 // `fp` should only be `None` in error cases (either erroneous code or incomplete name resolution)
297 // To better support custom derives, collect impls in all unnamed const items.
298 // const _: () = { ... };
299 for konst in module_data.scope.unnamed_consts() {
300 let body = db.body(konst.into());
301 for (_, block_def_map) in body.blocks(db.upcast()) {
302 self.collect_def_map(db, &block_def_map);
308 pub fn for_self_ty(&self, self_ty: &Ty) -> &[ImplId] {
309 match TyFingerprint::for_inherent_impl(self_ty) {
310 Some(fp) => self.map.get(&fp).map(|vec| vec.as_ref()).unwrap_or(&[]),
315 pub fn all_impls(&self) -> impl Iterator<Item = ImplId> + '_ {
316 self.map.values().flat_map(|v| v.iter().copied())
321 db: &dyn HirDatabase,
324 ) -> Option<ArrayVec<CrateId, 2>> {
325 // Types like slice can have inherent impls in several crates, (core and alloc).
326 // The corresponding impls are marked with lang items, so we can use them to find the required crates.
327 macro_rules! lang_item_crate {
328 ($($name:expr),+ $(,)?) => {{
329 let mut v = ArrayVec::<LangItemTarget, 2>::new();
331 v.extend(db.lang_item(cur_crate, $name.into()));
337 let mod_to_crate_ids = |module: ModuleId| Some(std::iter::once(module.krate()).collect());
339 let lang_item_targets = match ty.kind(&Interner) {
340 TyKind::Adt(AdtId(def_id), _) => {
341 return mod_to_crate_ids(def_id.module(db.upcast()));
343 TyKind::Foreign(id) => {
344 return mod_to_crate_ids(
345 from_foreign_def_id(*id).lookup(db.upcast()).module(db.upcast()),
348 TyKind::Scalar(Scalar::Bool) => lang_item_crate!("bool"),
349 TyKind::Scalar(Scalar::Char) => lang_item_crate!("char"),
350 TyKind::Scalar(Scalar::Float(f)) => match f {
351 // There are two lang items: one in libcore (fXX) and one in libstd (fXX_runtime)
352 FloatTy::F32 => lang_item_crate!("f32", "f32_runtime"),
353 FloatTy::F64 => lang_item_crate!("f64", "f64_runtime"),
355 &TyKind::Scalar(Scalar::Int(t)) => {
356 lang_item_crate!(primitive::int_ty_to_string(t))
358 &TyKind::Scalar(Scalar::Uint(t)) => {
359 lang_item_crate!(primitive::uint_ty_to_string(t))
361 TyKind::Str => lang_item_crate!("str_alloc", "str"),
362 TyKind::Slice(_) => lang_item_crate!("slice_alloc", "slice"),
363 TyKind::Array(..) => lang_item_crate!("array"),
364 TyKind::Raw(Mutability::Not, _) => lang_item_crate!("const_ptr"),
365 TyKind::Raw(Mutability::Mut, _) => lang_item_crate!("mut_ptr"),
367 return ty.dyn_trait().and_then(|trait_| {
368 mod_to_crate_ids(GenericDefId::TraitId(trait_).module(db.upcast()))
373 let res = lang_item_targets
375 .filter_map(|it| match it {
376 LangItemTarget::ImplDefId(it) => Some(it),
379 .map(|it| it.lookup(db.upcast()).container.krate())
384 /// Look up the method with the given name, returning the actual autoderefed
385 /// receiver type (but without autoref applied yet).
386 pub(crate) fn lookup_method(
388 db: &dyn HirDatabase,
389 env: Arc<TraitEnvironment>,
391 traits_in_scope: &FxHashSet<TraitId>,
392 visible_from_module: Option<ModuleId>,
394 ) -> Option<(Canonical<Ty>, FunctionId)> {
395 iterate_method_candidates(
403 LookupMode::MethodCall,
405 AssocItemId::FunctionId(f) => Some((ty.clone(), f)),
411 /// Whether we're looking up a dotted method call (like `v.len()`) or a path
412 /// (like `Vec::new`).
413 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
414 pub enum LookupMode {
415 /// Looking up a method call like `v.len()`: We only consider candidates
416 /// that have a `self` parameter, and do autoderef.
418 /// Looking up a path like `Vec::new` or `Vec::default`: We consider all
419 /// candidates including associated constants, but don't do autoderef.
423 // This would be nicer if it just returned an iterator, but that runs into
424 // lifetime problems, because we need to borrow temp `CrateImplDefs`.
425 // FIXME add a context type here?
426 pub fn iterate_method_candidates<T>(
428 db: &dyn HirDatabase,
429 env: Arc<TraitEnvironment>,
431 traits_in_scope: &FxHashSet<TraitId>,
432 visible_from_module: Option<ModuleId>,
435 mut callback: impl FnMut(&Canonical<Ty>, AssocItemId) -> Option<T>,
438 iterate_method_candidates_dyn(
448 assert!(slot.is_none());
449 if let Some(it) = callback(ty, item) {
451 return ControlFlow::Break(());
453 ControlFlow::Continue(())
459 pub fn iterate_method_candidates_dyn(
461 db: &dyn HirDatabase,
462 env: Arc<TraitEnvironment>,
464 traits_in_scope: &FxHashSet<TraitId>,
465 visible_from_module: Option<ModuleId>,
468 callback: &mut dyn FnMut(&Canonical<Ty>, AssocItemId) -> ControlFlow<()>,
469 ) -> ControlFlow<()> {
471 LookupMode::MethodCall => {
472 // For method calls, rust first does any number of autoderef, and then one
473 // autoref (i.e. when the method takes &self or &mut self). We just ignore
474 // the autoref currently -- when we find a method matching the given name,
475 // we assume it fits.
477 // Also note that when we've got a receiver like &S, even if the method we
478 // find in the end takes &self, we still do the autoderef step (just as
479 // rustc does an autoderef and then autoref again).
480 let ty = InEnvironment { goal: ty.clone(), environment: env.env.clone() };
482 // We have to be careful about the order we're looking at candidates
483 // in here. Consider the case where we're resolving `x.clone()`
484 // where `x: &Vec<_>`. This resolves to the clone method with self
485 // type `Vec<_>`, *not* `&_`. I.e. we need to consider methods where
486 // the receiver type exactly matches before cases where we have to
487 // do autoref. But in the autoderef steps, the `&_` self type comes
488 // up *before* the `Vec<_>` self type.
490 // On the other hand, we don't want to just pick any by-value method
491 // before any by-autoref method; it's just that we need to consider
492 // the methods by autoderef order of *receiver types*, not *self
495 let deref_chain = autoderef_method_receiver(db, krate, ty);
496 for i in 0..deref_chain.len() {
497 iterate_method_candidates_with_autoref(
508 ControlFlow::Continue(())
510 LookupMode::Path => {
511 // No autoderef for path lookups
512 iterate_method_candidates_for_self_ty(
526 fn iterate_method_candidates_with_autoref(
527 deref_chain: &[Canonical<Ty>],
528 db: &dyn HirDatabase,
529 env: Arc<TraitEnvironment>,
531 traits_in_scope: &FxHashSet<TraitId>,
532 visible_from_module: Option<ModuleId>,
534 mut callback: &mut dyn FnMut(&Canonical<Ty>, AssocItemId) -> ControlFlow<()>,
535 ) -> ControlFlow<()> {
536 iterate_method_candidates_by_receiver(
548 let refed = Canonical {
549 binders: deref_chain[0].binders.clone(),
550 value: TyKind::Ref(Mutability::Not, static_lifetime(), deref_chain[0].value.clone())
554 iterate_method_candidates_by_receiver(
566 let ref_muted = Canonical {
567 binders: deref_chain[0].binders.clone(),
568 value: TyKind::Ref(Mutability::Mut, static_lifetime(), deref_chain[0].value.clone())
572 iterate_method_candidates_by_receiver(
585 fn iterate_method_candidates_by_receiver(
586 receiver_ty: &Canonical<Ty>,
587 rest_of_deref_chain: &[Canonical<Ty>],
588 db: &dyn HirDatabase,
589 env: Arc<TraitEnvironment>,
591 traits_in_scope: &FxHashSet<TraitId>,
592 visible_from_module: Option<ModuleId>,
594 mut callback: &mut dyn FnMut(&Canonical<Ty>, AssocItemId) -> ControlFlow<()>,
595 ) -> ControlFlow<()> {
596 // We're looking for methods with *receiver* type receiver_ty. These could
597 // be found in any of the derefs of receiver_ty, so we have to go through
599 for self_ty in std::iter::once(receiver_ty).chain(rest_of_deref_chain) {
600 iterate_inherent_methods(
612 for self_ty in std::iter::once(receiver_ty).chain(rest_of_deref_chain) {
613 iterate_trait_method_candidates(
625 ControlFlow::Continue(())
628 fn iterate_method_candidates_for_self_ty(
629 self_ty: &Canonical<Ty>,
630 db: &dyn HirDatabase,
631 env: Arc<TraitEnvironment>,
633 traits_in_scope: &FxHashSet<TraitId>,
634 visible_from_module: Option<ModuleId>,
636 mut callback: &mut dyn FnMut(&Canonical<Ty>, AssocItemId) -> ControlFlow<()>,
637 ) -> ControlFlow<()> {
638 iterate_inherent_methods(
648 iterate_trait_method_candidates(self_ty, db, env, krate, traits_in_scope, name, None, callback)
651 fn iterate_trait_method_candidates(
652 self_ty: &Canonical<Ty>,
653 db: &dyn HirDatabase,
654 env: Arc<TraitEnvironment>,
656 traits_in_scope: &FxHashSet<TraitId>,
658 receiver_ty: Option<&Canonical<Ty>>,
659 callback: &mut dyn FnMut(&Canonical<Ty>, AssocItemId) -> ControlFlow<()>,
660 ) -> ControlFlow<()> {
661 let receiver_is_array = matches!(self_ty.value.kind(&Interner), chalk_ir::TyKind::Array(..));
662 // if ty is `dyn Trait`, the trait doesn't need to be in scope
664 self_ty.value.dyn_trait().into_iter().flat_map(|t| all_super_traits(db.upcast(), t));
665 let env_traits = match self_ty.value.kind(&Interner) {
666 TyKind::Placeholder(_) => {
667 // if we have `T: Trait` in the param env, the trait doesn't need to be in scope
668 env.traits_in_scope_from_clauses(&self_ty.value)
669 .flat_map(|t| all_super_traits(db.upcast(), t))
675 inherent_trait.chain(env_traits.into_iter()).chain(traits_in_scope.iter().copied());
677 'traits: for t in traits {
678 let data = db.trait_data(t);
680 // Traits annotated with `#[rustc_skip_array_during_method_dispatch]` are skipped during
681 // method resolution, if the receiver is an array, and we're compiling for editions before
683 // This is to make `[a].into_iter()` not break code with the new `IntoIterator` impl for
685 if data.skip_array_during_method_dispatch && receiver_is_array {
686 // FIXME: this should really be using the edition of the method name's span, in case it
687 // comes from a macro
688 if db.crate_graph()[krate].edition < Edition::Edition2021 {
693 // we'll be lazy about checking whether the type implements the
694 // trait, but if we find out it doesn't, we'll skip the rest of the
696 let mut known_implemented = false;
697 for (_name, item) in data.items.iter() {
698 // Don't pass a `visible_from_module` down to `is_valid_candidate`,
699 // since only inherent methods should be included into visibility checking.
700 if !is_valid_candidate(db, env.clone(), name, receiver_ty, *item, self_ty, None) {
703 if !known_implemented {
704 let goal = generic_implements_goal(db, env.clone(), t, self_ty.clone());
705 if db.trait_solve(krate, goal.cast(&Interner)).is_none() {
709 known_implemented = true;
710 // FIXME: we shouldn't be ignoring the binders here
711 callback(self_ty, *item)?
714 ControlFlow::Continue(())
717 fn filter_inherent_impls_for_self_ty<'i>(
718 impls: &'i InherentImpls,
720 ) -> impl Iterator<Item = &'i ImplId> {
721 // inherent methods on arrays are fingerprinted as [T; {unknown}], so we must also consider them when
722 // resolving a method call on an array with a known len
724 if let TyKind::Array(parameters, array_len) = self_ty.kind(&Interner) {
725 if !array_len.is_unknown() {
726 let unknown_array_len_ty =
727 TyKind::Array(parameters.clone(), consteval::usize_const(None))
730 Some(impls.for_self_ty(&unknown_array_len_ty))
741 impls.for_self_ty(self_ty).iter().chain(array_impls)
744 fn iterate_inherent_methods(
745 self_ty: &Canonical<Ty>,
746 db: &dyn HirDatabase,
747 env: Arc<TraitEnvironment>,
749 receiver_ty: Option<&Canonical<Ty>>,
751 visible_from_module: Option<ModuleId>,
752 callback: &mut dyn FnMut(&Canonical<Ty>, AssocItemId) -> ControlFlow<()>,
753 ) -> ControlFlow<()> {
754 let def_crates = match def_crates(db, &self_ty.value, krate) {
756 None => return ControlFlow::Continue(()),
759 if let Some(module_id) = visible_from_module {
760 if let Some(block_id) = module_id.containing_block() {
761 if let Some(impls) = db.inherent_impls_in_block(block_id) {
776 for krate in def_crates {
777 let impls = db.inherent_impls_in_crate(krate);
789 return ControlFlow::Continue(());
791 fn impls_for_self_ty(
792 impls: &InherentImpls,
793 self_ty: &Canonical<Ty>,
794 db: &dyn HirDatabase,
795 env: Arc<TraitEnvironment>,
797 receiver_ty: Option<&Canonical<Ty>>,
798 visible_from_module: Option<ModuleId>,
799 callback: &mut dyn FnMut(&Canonical<Ty>, AssocItemId) -> ControlFlow<()>,
800 ) -> ControlFlow<()> {
801 let impls_for_self_ty = filter_inherent_impls_for_self_ty(impls, &self_ty.value);
802 for &impl_def in impls_for_self_ty {
803 for &item in db.impl_data(impl_def).items.iter() {
804 if !is_valid_candidate(
815 // we have to check whether the self type unifies with the type
816 // that the impl is for. If we have a receiver type, this
817 // already happens in `is_valid_candidate` above; if not, we
819 if receiver_ty.is_none()
820 && inherent_impl_substs(db, env.clone(), impl_def, self_ty).is_none()
822 cov_mark::hit!(impl_self_type_match_without_receiver);
825 let receiver_ty = receiver_ty.unwrap_or(self_ty);
826 callback(receiver_ty, item)?;
829 ControlFlow::Continue(())
833 /// Returns the self type for the index trait call.
834 pub fn resolve_indexing_op(
835 db: &dyn HirDatabase,
837 env: Arc<TraitEnvironment>,
839 index_trait: TraitId,
840 ) -> Option<Canonical<Ty>> {
841 let ty = InEnvironment { goal: ty.clone(), environment: env.env.clone() };
842 let deref_chain = autoderef_method_receiver(db, krate, ty);
843 for ty in deref_chain {
844 let goal = generic_implements_goal(db, env.clone(), index_trait, ty.clone());
845 if db.trait_solve(krate, goal.cast(&Interner)).is_some() {
852 fn is_transformed_receiver_ty_equal(transformed_receiver_ty: &Ty, receiver_ty: &Ty) -> bool {
853 if transformed_receiver_ty == receiver_ty {
857 // a transformed receiver may be considered equal (and a valid method call candidate) if it is an array
858 // with an unknown (i.e. generic) length, and the receiver is an array with the same item type but a known len,
859 // this allows inherent methods on arrays to be considered valid resolution candidates
860 match (transformed_receiver_ty.kind(&Interner), receiver_ty.kind(&Interner)) {
862 TyKind::Array(transformed_array_ty, transformed_array_len),
863 TyKind::Array(receiver_array_ty, receiver_array_len),
864 ) if transformed_array_ty == receiver_array_ty
865 && transformed_array_len.is_unknown()
866 && !receiver_array_len.is_unknown() =>
874 fn is_valid_candidate(
875 db: &dyn HirDatabase,
876 env: Arc<TraitEnvironment>,
878 receiver_ty: Option<&Canonical<Ty>>,
880 self_ty: &Canonical<Ty>,
881 visible_from_module: Option<ModuleId>,
884 AssocItemId::FunctionId(m) => {
885 let data = db.function_data(m);
886 if let Some(name) = name {
887 if &data.name != name {
891 if let Some(receiver_ty) = receiver_ty {
892 if !data.has_self_param() {
895 let transformed_receiver_ty = match transform_receiver_ty(db, env, m, self_ty) {
897 None => return false,
900 if !is_transformed_receiver_ty_equal(&transformed_receiver_ty, &receiver_ty.value) {
904 if let Some(from_module) = visible_from_module {
905 if !db.function_visibility(m).is_visible_from(db.upcast(), from_module) {
906 cov_mark::hit!(autoderef_candidate_not_visible);
913 AssocItemId::ConstId(c) => {
914 let data = db.const_data(c);
915 name.map_or(true, |name| data.name.as_ref() == Some(name)) && receiver_ty.is_none()
921 pub(crate) fn inherent_impl_substs(
922 db: &dyn HirDatabase,
923 env: Arc<TraitEnvironment>,
925 self_ty: &Canonical<Ty>,
926 ) -> Option<Substitution> {
927 // we create a var for each type parameter of the impl; we need to keep in
928 // mind here that `self_ty` might have vars of its own
929 let self_ty_vars = self_ty.binders.len(&Interner);
930 let vars = TyBuilder::subst_for_def(db, impl_id)
931 .fill_with_bound_vars(DebruijnIndex::INNERMOST, self_ty_vars)
933 let self_ty_with_vars = db.impl_self_ty(impl_id).substitute(&Interner, &vars);
934 let mut kinds = self_ty.binders.interned().to_vec();
936 iter::repeat(chalk_ir::WithKind::new(
937 chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
940 .take(vars.len(&Interner)),
942 let tys = Canonical {
943 binders: CanonicalVarKinds::from_iter(&Interner, kinds),
944 value: (self_ty_with_vars, self_ty.value.clone()),
946 let substs = super::infer::unify(db, env, &tys)?;
947 // We only want the substs for the vars we added, not the ones from self_ty.
948 // Also, if any of the vars we added are still in there, we replace them by
949 // Unknown. I think this can only really happen if self_ty contained
950 // Unknown, and in that case we want the result to contain Unknown in those
953 Substitution::from_iter(&Interner, substs.iter(&Interner).cloned().skip(self_ty_vars));
954 Some(fallback_bound_vars(suffix, self_ty_vars))
957 /// This replaces any 'free' Bound vars in `s` (i.e. those with indices past
958 /// num_vars_to_keep) by `TyKind::Unknown`.
959 fn fallback_bound_vars(s: Substitution, num_vars_to_keep: usize) -> Substitution {
960 crate::fold_free_vars(s, |bound, binders| {
961 if bound.index >= num_vars_to_keep && bound.debruijn == DebruijnIndex::INNERMOST {
962 TyKind::Error.intern(&Interner)
964 bound.shifted_in_from(binders).to_ty(&Interner)
969 fn transform_receiver_ty(
970 db: &dyn HirDatabase,
971 env: Arc<TraitEnvironment>,
972 function_id: FunctionId,
973 self_ty: &Canonical<Ty>,
975 let substs = match function_id.lookup(db.upcast()).container {
976 AssocContainerId::TraitId(_) => TyBuilder::subst_for_def(db, function_id)
977 .push(self_ty.value.clone())
980 AssocContainerId::ImplId(impl_id) => {
981 let impl_substs = inherent_impl_substs(db, env, impl_id, self_ty)?;
982 TyBuilder::subst_for_def(db, function_id)
983 .use_parent_substs(&impl_substs)
987 AssocContainerId::ModuleId(_) => unreachable!(),
989 let sig = db.callable_item_signature(function_id.into());
990 Some(sig.map(|s| s.params()[0].clone()).substitute(&Interner, &substs))
993 pub fn implements_trait(
995 db: &dyn HirDatabase,
996 env: Arc<TraitEnvironment>,
1000 let goal = generic_implements_goal(db, env, trait_, ty.clone());
1001 let solution = db.trait_solve(krate, goal.cast(&Interner));
1006 pub fn implements_trait_unique(
1008 db: &dyn HirDatabase,
1009 env: Arc<TraitEnvironment>,
1013 let goal = generic_implements_goal(db, env, trait_, ty.clone());
1014 let solution = db.trait_solve(krate, goal.cast(&Interner));
1016 matches!(solution, Some(crate::Solution::Unique(_)))
1019 /// This creates Substs for a trait with the given Self type and type variables
1020 /// for all other parameters, to query Chalk with it.
1021 fn generic_implements_goal(
1022 db: &dyn HirDatabase,
1023 env: Arc<TraitEnvironment>,
1025 self_ty: Canonical<Ty>,
1026 ) -> Canonical<InEnvironment<super::DomainGoal>> {
1027 let mut kinds = self_ty.binders.interned().to_vec();
1028 let trait_ref = TyBuilder::trait_ref(db, trait_)
1029 .push(self_ty.value)
1030 .fill_with_bound_vars(DebruijnIndex::INNERMOST, kinds.len())
1033 iter::repeat(chalk_ir::WithKind::new(
1034 chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General),
1035 UniverseIndex::ROOT,
1037 .take(trait_ref.substitution.len(&Interner) - 1),
1039 let obligation = trait_ref.cast(&Interner);
1041 binders: CanonicalVarKinds::from_iter(&Interner, kinds),
1042 value: InEnvironment::new(&env.env, obligation),
1046 fn autoderef_method_receiver(
1047 db: &dyn HirDatabase,
1049 ty: InEnvironment<Canonical<Ty>>,
1050 ) -> Vec<Canonical<Ty>> {
1051 let mut deref_chain: Vec<_> = autoderef::autoderef(db, Some(krate), ty).collect();
1052 // As a last step, we can do array unsizing (that's the only unsizing that rustc does for method receivers!)
1053 if let Some(TyKind::Array(parameters, _)) =
1054 deref_chain.last().map(|ty| ty.value.kind(&Interner))
1056 let kinds = deref_chain.last().unwrap().binders.clone();
1057 let unsized_ty = TyKind::Slice(parameters.clone()).intern(&Interner);
1058 deref_chain.push(Canonical { value: unsized_ty, binders: kinds })