Unnamed repository; edit this file 'description' to name the repository.
Diffstat (limited to 'crates/hir-ty/src/method_resolution.rs')
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diff --git a/crates/hir-ty/src/method_resolution.rs b/crates/hir-ty/src/method_resolution.rs new file mode 100644 index 0000000000..d5285c1710 --- /dev/null +++ b/crates/hir-ty/src/method_resolution.rs @@ -0,0 +1,1138 @@ +//! This module is concerned with finding methods that a given type provides. +//! For details about how this works in rustc, see the method lookup page in the +//! [rustc guide](https://rust-lang.github.io/rustc-guide/method-lookup.html) +//! and the corresponding code mostly in librustc_typeck/check/method/probe.rs. +use std::{iter, ops::ControlFlow, sync::Arc}; + +use arrayvec::ArrayVec; +use base_db::{CrateId, Edition}; +use chalk_ir::{cast::Cast, Mutability, UniverseIndex}; +use hir_def::{ + item_scope::ItemScope, nameres::DefMap, AssocItemId, BlockId, ConstId, FunctionId, + GenericDefId, HasModule, ImplId, ItemContainerId, Lookup, ModuleDefId, ModuleId, TraitId, +}; +use hir_expand::name::Name; +use rustc_hash::{FxHashMap, FxHashSet}; +use stdx::never; + +use crate::{ + autoderef::{self, AutoderefKind}, + db::HirDatabase, + from_foreign_def_id, + infer::{unify::InferenceTable, Adjust, Adjustment, AutoBorrow, OverloadedDeref, PointerCast}, + primitive::{FloatTy, IntTy, UintTy}, + static_lifetime, + utils::all_super_traits, + AdtId, Canonical, CanonicalVarKinds, DebruijnIndex, ForeignDefId, InEnvironment, Interner, + Scalar, TraitEnvironment, TraitRefExt, Ty, TyBuilder, TyExt, TyKind, +}; + +/// This is used as a key for indexing impls. +#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)] +pub enum TyFingerprint { + // These are lang item impls: + Str, + Slice, + Array, + Never, + RawPtr(Mutability), + Scalar(Scalar), + // These can have user-defined impls: + Adt(hir_def::AdtId), + Dyn(TraitId), + ForeignType(ForeignDefId), + // These only exist for trait impls + Unit, + Unnameable, + Function(u32), +} + +impl TyFingerprint { + /// Creates a TyFingerprint for looking up an inherent impl. Only certain + /// types can have inherent impls: if we have some `struct S`, we can have + /// an `impl S`, but not `impl &S`. Hence, this will return `None` for + /// reference types and such. + pub fn for_inherent_impl(ty: &Ty) -> Option<TyFingerprint> { + let fp = match ty.kind(Interner) { + TyKind::Str => TyFingerprint::Str, + TyKind::Never => TyFingerprint::Never, + TyKind::Slice(..) => TyFingerprint::Slice, + TyKind::Array(..) => TyFingerprint::Array, + TyKind::Scalar(scalar) => TyFingerprint::Scalar(*scalar), + TyKind::Adt(AdtId(adt), _) => TyFingerprint::Adt(*adt), + TyKind::Raw(mutability, ..) => TyFingerprint::RawPtr(*mutability), + TyKind::Foreign(alias_id, ..) => TyFingerprint::ForeignType(*alias_id), + TyKind::Dyn(_) => ty.dyn_trait().map(TyFingerprint::Dyn)?, + _ => return None, + }; + Some(fp) + } + + /// Creates a TyFingerprint for looking up a trait impl. + pub fn for_trait_impl(ty: &Ty) -> Option<TyFingerprint> { + let fp = match ty.kind(Interner) { + TyKind::Str => TyFingerprint::Str, + TyKind::Never => TyFingerprint::Never, + TyKind::Slice(..) => TyFingerprint::Slice, + TyKind::Array(..) => TyFingerprint::Array, + TyKind::Scalar(scalar) => TyFingerprint::Scalar(*scalar), + TyKind::Adt(AdtId(adt), _) => TyFingerprint::Adt(*adt), + TyKind::Raw(mutability, ..) => TyFingerprint::RawPtr(*mutability), + TyKind::Foreign(alias_id, ..) => TyFingerprint::ForeignType(*alias_id), + TyKind::Dyn(_) => ty.dyn_trait().map(TyFingerprint::Dyn)?, + TyKind::Ref(_, _, ty) => return TyFingerprint::for_trait_impl(ty), + TyKind::Tuple(_, subst) => { + let first_ty = subst.interned().get(0).map(|arg| arg.assert_ty_ref(Interner)); + match first_ty { + Some(ty) => return TyFingerprint::for_trait_impl(ty), + None => TyFingerprint::Unit, + } + } + TyKind::AssociatedType(_, _) + | TyKind::OpaqueType(_, _) + | TyKind::FnDef(_, _) + | TyKind::Closure(_, _) + | TyKind::Generator(..) + | TyKind::GeneratorWitness(..) => TyFingerprint::Unnameable, + TyKind::Function(fn_ptr) => { + TyFingerprint::Function(fn_ptr.substitution.0.len(Interner) as u32) + } + TyKind::Alias(_) + | TyKind::Placeholder(_) + | TyKind::BoundVar(_) + | TyKind::InferenceVar(_, _) + | TyKind::Error => return None, + }; + Some(fp) + } +} + +pub(crate) const ALL_INT_FPS: [TyFingerprint; 12] = [ + TyFingerprint::Scalar(Scalar::Int(IntTy::I8)), + TyFingerprint::Scalar(Scalar::Int(IntTy::I16)), + TyFingerprint::Scalar(Scalar::Int(IntTy::I32)), + TyFingerprint::Scalar(Scalar::Int(IntTy::I64)), + TyFingerprint::Scalar(Scalar::Int(IntTy::I128)), + TyFingerprint::Scalar(Scalar::Int(IntTy::Isize)), + TyFingerprint::Scalar(Scalar::Uint(UintTy::U8)), + TyFingerprint::Scalar(Scalar::Uint(UintTy::U16)), + TyFingerprint::Scalar(Scalar::Uint(UintTy::U32)), + TyFingerprint::Scalar(Scalar::Uint(UintTy::U64)), + TyFingerprint::Scalar(Scalar::Uint(UintTy::U128)), + TyFingerprint::Scalar(Scalar::Uint(UintTy::Usize)), +]; + +pub(crate) const ALL_FLOAT_FPS: [TyFingerprint; 2] = [ + TyFingerprint::Scalar(Scalar::Float(FloatTy::F32)), + TyFingerprint::Scalar(Scalar::Float(FloatTy::F64)), +]; + +/// Trait impls defined or available in some crate. +#[derive(Debug, Eq, PartialEq)] +pub struct TraitImpls { + // If the `Option<TyFingerprint>` is `None`, the impl may apply to any self type. + map: FxHashMap<TraitId, FxHashMap<Option<TyFingerprint>, Vec<ImplId>>>, +} + +impl TraitImpls { + pub(crate) fn trait_impls_in_crate_query(db: &dyn HirDatabase, krate: CrateId) -> Arc<Self> { + let _p = profile::span("trait_impls_in_crate_query"); + let mut impls = Self { map: FxHashMap::default() }; + + let crate_def_map = db.crate_def_map(krate); + impls.collect_def_map(db, &crate_def_map); + impls.shrink_to_fit(); + + Arc::new(impls) + } + + pub(crate) fn trait_impls_in_block_query( + db: &dyn HirDatabase, + block: BlockId, + ) -> Option<Arc<Self>> { + let _p = profile::span("trait_impls_in_block_query"); + let mut impls = Self { map: FxHashMap::default() }; + + let block_def_map = db.block_def_map(block)?; + impls.collect_def_map(db, &block_def_map); + impls.shrink_to_fit(); + + Some(Arc::new(impls)) + } + + pub(crate) fn trait_impls_in_deps_query(db: &dyn HirDatabase, krate: CrateId) -> Arc<Self> { + let _p = profile::span("trait_impls_in_deps_query"); + let crate_graph = db.crate_graph(); + let mut res = Self { map: FxHashMap::default() }; + + for krate in crate_graph.transitive_deps(krate) { + res.merge(&db.trait_impls_in_crate(krate)); + } + res.shrink_to_fit(); + + Arc::new(res) + } + + fn shrink_to_fit(&mut self) { + self.map.shrink_to_fit(); + self.map.values_mut().for_each(|map| { + map.shrink_to_fit(); + map.values_mut().for_each(Vec::shrink_to_fit); + }); + } + + fn collect_def_map(&mut self, db: &dyn HirDatabase, def_map: &DefMap) { + for (_module_id, module_data) in def_map.modules() { + for impl_id in module_data.scope.impls() { + let target_trait = match db.impl_trait(impl_id) { + Some(tr) => tr.skip_binders().hir_trait_id(), + None => continue, + }; + let self_ty = db.impl_self_ty(impl_id); + let self_ty_fp = TyFingerprint::for_trait_impl(self_ty.skip_binders()); + self.map + .entry(target_trait) + .or_default() + .entry(self_ty_fp) + .or_default() + .push(impl_id); + } + + // To better support custom derives, collect impls in all unnamed const items. + // const _: () = { ... }; + for konst in collect_unnamed_consts(db, &module_data.scope) { + let body = db.body(konst.into()); + for (_, block_def_map) in body.blocks(db.upcast()) { + self.collect_def_map(db, &block_def_map); + } + } + } + } + + fn merge(&mut self, other: &Self) { + for (trait_, other_map) in &other.map { + let map = self.map.entry(*trait_).or_default(); + for (fp, impls) in other_map { + let vec = map.entry(*fp).or_default(); + vec.extend(impls); + } + } + } + + /// Queries all trait impls for the given type. + pub fn for_self_ty_without_blanket_impls( + &self, + fp: TyFingerprint, + ) -> impl Iterator<Item = ImplId> + '_ { + self.map + .values() + .flat_map(move |impls| impls.get(&Some(fp)).into_iter()) + .flat_map(|it| it.iter().copied()) + } + + /// Queries all impls of the given trait. + pub fn for_trait(&self, trait_: TraitId) -> impl Iterator<Item = ImplId> + '_ { + self.map + .get(&trait_) + .into_iter() + .flat_map(|map| map.values().flat_map(|v| v.iter().copied())) + } + + /// Queries all impls of `trait_` that may apply to `self_ty`. + pub fn for_trait_and_self_ty( + &self, + trait_: TraitId, + self_ty: TyFingerprint, + ) -> impl Iterator<Item = ImplId> + '_ { + self.map + .get(&trait_) + .into_iter() + .flat_map(move |map| map.get(&None).into_iter().chain(map.get(&Some(self_ty)))) + .flat_map(|v| v.iter().copied()) + } + + pub fn all_impls(&self) -> impl Iterator<Item = ImplId> + '_ { + self.map.values().flat_map(|map| map.values().flat_map(|v| v.iter().copied())) + } +} + +/// Inherent impls defined in some crate. +/// +/// Inherent impls can only be defined in the crate that also defines the self type of the impl +/// (note that some primitives are considered to be defined by both libcore and liballoc). +/// +/// This makes inherent impl lookup easier than trait impl lookup since we only have to consider a +/// single crate. +#[derive(Debug, Eq, PartialEq)] +pub struct InherentImpls { + map: FxHashMap<TyFingerprint, Vec<ImplId>>, +} + +impl InherentImpls { + pub(crate) fn inherent_impls_in_crate_query(db: &dyn HirDatabase, krate: CrateId) -> Arc<Self> { + let mut impls = Self { map: FxHashMap::default() }; + + let crate_def_map = db.crate_def_map(krate); + impls.collect_def_map(db, &crate_def_map); + impls.shrink_to_fit(); + + Arc::new(impls) + } + + pub(crate) fn inherent_impls_in_block_query( + db: &dyn HirDatabase, + block: BlockId, + ) -> Option<Arc<Self>> { + let mut impls = Self { map: FxHashMap::default() }; + if let Some(block_def_map) = db.block_def_map(block) { + impls.collect_def_map(db, &block_def_map); + impls.shrink_to_fit(); + return Some(Arc::new(impls)); + } + None + } + + fn shrink_to_fit(&mut self) { + self.map.values_mut().for_each(Vec::shrink_to_fit); + self.map.shrink_to_fit(); + } + + fn collect_def_map(&mut self, db: &dyn HirDatabase, def_map: &DefMap) { + for (_module_id, module_data) in def_map.modules() { + for impl_id in module_data.scope.impls() { + let data = db.impl_data(impl_id); + if data.target_trait.is_some() { + continue; + } + + let self_ty = db.impl_self_ty(impl_id); + let fp = TyFingerprint::for_inherent_impl(self_ty.skip_binders()); + if let Some(fp) = fp { + self.map.entry(fp).or_default().push(impl_id); + } + // `fp` should only be `None` in error cases (either erroneous code or incomplete name resolution) + } + + // To better support custom derives, collect impls in all unnamed const items. + // const _: () = { ... }; + for konst in collect_unnamed_consts(db, &module_data.scope) { + let body = db.body(konst.into()); + for (_, block_def_map) in body.blocks(db.upcast()) { + self.collect_def_map(db, &block_def_map); + } + } + } + } + + pub fn for_self_ty(&self, self_ty: &Ty) -> &[ImplId] { + match TyFingerprint::for_inherent_impl(self_ty) { + Some(fp) => self.map.get(&fp).map(|vec| vec.as_ref()).unwrap_or(&[]), + None => &[], + } + } + + pub fn all_impls(&self) -> impl Iterator<Item = ImplId> + '_ { + self.map.values().flat_map(|v| v.iter().copied()) + } +} + +pub fn inherent_impl_crates_query( + db: &dyn HirDatabase, + krate: CrateId, + fp: TyFingerprint, +) -> ArrayVec<CrateId, 2> { + let _p = profile::span("inherent_impl_crates_query"); + let mut res = ArrayVec::new(); + let crate_graph = db.crate_graph(); + + for krate in crate_graph.transitive_deps(krate) { + if res.is_full() { + // we don't currently look for or store more than two crates here, + // so don't needlessly look at more crates than necessary. + break; + } + let impls = db.inherent_impls_in_crate(krate); + if impls.map.get(&fp).map_or(false, |v| !v.is_empty()) { + res.push(krate); + } + } + + res +} + +fn collect_unnamed_consts<'a>( + db: &'a dyn HirDatabase, + scope: &'a ItemScope, +) -> impl Iterator<Item = ConstId> + 'a { + let unnamed_consts = scope.unnamed_consts(); + + // FIXME: Also treat consts named `_DERIVE_*` as unnamed, since synstructure generates those. + // Should be removed once synstructure stops doing that. + let synstructure_hack_consts = scope.values().filter_map(|(item, _)| match item { + ModuleDefId::ConstId(id) => { + let loc = id.lookup(db.upcast()); + let item_tree = loc.id.item_tree(db.upcast()); + if item_tree[loc.id.value] + .name + .as_ref() + .map_or(false, |n| n.to_smol_str().starts_with("_DERIVE_")) + { + Some(id) + } else { + None + } + } + _ => None, + }); + + unnamed_consts.chain(synstructure_hack_consts) +} + +pub fn def_crates( + db: &dyn HirDatabase, + ty: &Ty, + cur_crate: CrateId, +) -> Option<ArrayVec<CrateId, 2>> { + let mod_to_crate_ids = |module: ModuleId| Some(iter::once(module.krate()).collect()); + + let fp = TyFingerprint::for_inherent_impl(ty); + + match ty.kind(Interner) { + TyKind::Adt(AdtId(def_id), _) => mod_to_crate_ids(def_id.module(db.upcast())), + TyKind::Foreign(id) => { + mod_to_crate_ids(from_foreign_def_id(*id).lookup(db.upcast()).module(db.upcast())) + } + TyKind::Dyn(_) => ty + .dyn_trait() + .and_then(|trait_| mod_to_crate_ids(GenericDefId::TraitId(trait_).module(db.upcast()))), + // for primitives, there may be impls in various places (core and alloc + // mostly). We just check the whole crate graph for crates with impls + // (cached behind a query). + TyKind::Scalar(_) + | TyKind::Str + | TyKind::Slice(_) + | TyKind::Array(..) + | TyKind::Raw(..) => { + Some(db.inherent_impl_crates(cur_crate, fp.expect("fingerprint for primitive"))) + } + _ => return None, + } +} + +/// Look up the method with the given name. +pub(crate) fn lookup_method( + ty: &Canonical<Ty>, + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + traits_in_scope: &FxHashSet<TraitId>, + visible_from_module: VisibleFromModule, + name: &Name, +) -> Option<(ReceiverAdjustments, FunctionId)> { + iterate_method_candidates( + ty, + db, + env, + traits_in_scope, + visible_from_module, + Some(name), + LookupMode::MethodCall, + |adjustments, f| match f { + AssocItemId::FunctionId(f) => Some((adjustments, f)), + _ => None, + }, + ) +} + +/// Whether we're looking up a dotted method call (like `v.len()`) or a path +/// (like `Vec::new`). +#[derive(Copy, Clone, Debug, PartialEq, Eq)] +pub enum LookupMode { + /// Looking up a method call like `v.len()`: We only consider candidates + /// that have a `self` parameter, and do autoderef. + MethodCall, + /// Looking up a path like `Vec::new` or `Vec::default`: We consider all + /// candidates including associated constants, but don't do autoderef. + Path, +} + +#[derive(Clone, Copy)] +pub enum VisibleFromModule { + /// Filter for results that are visible from the given module + Filter(ModuleId), + /// Include impls from the given block. + IncludeBlock(BlockId), + /// Do nothing special in regards visibility + None, +} + +impl From<Option<ModuleId>> for VisibleFromModule { + fn from(module: Option<ModuleId>) -> Self { + match module { + Some(module) => Self::Filter(module), + None => Self::None, + } + } +} + +impl From<Option<BlockId>> for VisibleFromModule { + fn from(block: Option<BlockId>) -> Self { + match block { + Some(block) => Self::IncludeBlock(block), + None => Self::None, + } + } +} + +#[derive(Debug, Clone, Default)] +pub struct ReceiverAdjustments { + autoref: Option<Mutability>, + autoderefs: usize, + unsize_array: bool, +} + +impl ReceiverAdjustments { + pub(crate) fn apply(&self, table: &mut InferenceTable, ty: Ty) -> (Ty, Vec<Adjustment>) { + let mut ty = ty; + let mut adjust = Vec::new(); + for _ in 0..self.autoderefs { + match autoderef::autoderef_step(table, ty.clone()) { + None => { + never!("autoderef not possible for {:?}", ty); + ty = TyKind::Error.intern(Interner); + break; + } + Some((kind, new_ty)) => { + ty = new_ty.clone(); + adjust.push(Adjustment { + kind: Adjust::Deref(match kind { + // FIXME should we know the mutability here? + AutoderefKind::Overloaded => Some(OverloadedDeref(Mutability::Not)), + AutoderefKind::Builtin => None, + }), + target: new_ty, + }); + } + } + } + if self.unsize_array { + ty = match ty.kind(Interner) { + TyKind::Array(inner, _) => TyKind::Slice(inner.clone()).intern(Interner), + _ => { + never!("unsize_array with non-array {:?}", ty); + ty + } + }; + // FIXME this is kind of wrong since the unsize needs to happen to a pointer/reference + adjust.push(Adjustment { + kind: Adjust::Pointer(PointerCast::Unsize), + target: ty.clone(), + }); + } + if let Some(m) = self.autoref { + ty = TyKind::Ref(m, static_lifetime(), ty).intern(Interner); + adjust + .push(Adjustment { kind: Adjust::Borrow(AutoBorrow::Ref(m)), target: ty.clone() }); + } + (ty, adjust) + } + + fn with_autoref(&self, m: Mutability) -> ReceiverAdjustments { + Self { autoref: Some(m), ..*self } + } +} + +// This would be nicer if it just returned an iterator, but that runs into +// lifetime problems, because we need to borrow temp `CrateImplDefs`. +// FIXME add a context type here? +pub(crate) fn iterate_method_candidates<T>( + ty: &Canonical<Ty>, + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + traits_in_scope: &FxHashSet<TraitId>, + visible_from_module: VisibleFromModule, + name: Option<&Name>, + mode: LookupMode, + mut callback: impl FnMut(ReceiverAdjustments, AssocItemId) -> Option<T>, +) -> Option<T> { + let mut slot = None; + iterate_method_candidates_dyn( + ty, + db, + env, + traits_in_scope, + visible_from_module, + name, + mode, + &mut |adj, item| { + assert!(slot.is_none()); + if let Some(it) = callback(adj, item) { + slot = Some(it); + return ControlFlow::Break(()); + } + ControlFlow::Continue(()) + }, + ); + slot +} + +pub fn iterate_path_candidates( + ty: &Canonical<Ty>, + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + traits_in_scope: &FxHashSet<TraitId>, + visible_from_module: VisibleFromModule, + name: Option<&Name>, + callback: &mut dyn FnMut(AssocItemId) -> ControlFlow<()>, +) -> ControlFlow<()> { + iterate_method_candidates_dyn( + ty, + db, + env, + traits_in_scope, + visible_from_module, + name, + LookupMode::Path, + // the adjustments are not relevant for path lookup + &mut |_, id| callback(id), + ) +} + +pub fn iterate_method_candidates_dyn( + ty: &Canonical<Ty>, + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + traits_in_scope: &FxHashSet<TraitId>, + visible_from_module: VisibleFromModule, + name: Option<&Name>, + mode: LookupMode, + callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, +) -> ControlFlow<()> { + match mode { + LookupMode::MethodCall => { + // For method calls, rust first does any number of autoderef, and + // then one autoref (i.e. when the method takes &self or &mut self). + // Note that when we've got a receiver like &S, even if the method + // we find in the end takes &self, we still do the autoderef step + // (just as rustc does an autoderef and then autoref again). + + // We have to be careful about the order we're looking at candidates + // in here. Consider the case where we're resolving `x.clone()` + // where `x: &Vec<_>`. This resolves to the clone method with self + // type `Vec<_>`, *not* `&_`. I.e. we need to consider methods where + // the receiver type exactly matches before cases where we have to + // do autoref. But in the autoderef steps, the `&_` self type comes + // up *before* the `Vec<_>` self type. + // + // On the other hand, we don't want to just pick any by-value method + // before any by-autoref method; it's just that we need to consider + // the methods by autoderef order of *receiver types*, not *self + // types*. + + let mut table = InferenceTable::new(db, env.clone()); + let ty = table.instantiate_canonical(ty.clone()); + let (deref_chain, adj) = autoderef_method_receiver(&mut table, ty); + + let result = deref_chain.into_iter().zip(adj).try_for_each(|(receiver_ty, adj)| { + iterate_method_candidates_with_autoref( + &receiver_ty, + adj, + db, + env.clone(), + traits_in_scope, + visible_from_module, + name, + callback, + ) + }); + result + } + LookupMode::Path => { + // No autoderef for path lookups + iterate_method_candidates_for_self_ty( + ty, + db, + env, + traits_in_scope, + visible_from_module, + name, + callback, + ) + } + } +} + +fn iterate_method_candidates_with_autoref( + receiver_ty: &Canonical<Ty>, + first_adjustment: ReceiverAdjustments, + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + traits_in_scope: &FxHashSet<TraitId>, + visible_from_module: VisibleFromModule, + name: Option<&Name>, + mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, +) -> ControlFlow<()> { + if receiver_ty.value.is_general_var(Interner, &receiver_ty.binders) { + // don't try to resolve methods on unknown types + return ControlFlow::Continue(()); + } + + iterate_method_candidates_by_receiver( + receiver_ty, + first_adjustment.clone(), + db, + env.clone(), + traits_in_scope, + visible_from_module, + name, + &mut callback, + )?; + + let refed = Canonical { + value: TyKind::Ref(Mutability::Not, static_lifetime(), receiver_ty.value.clone()) + .intern(Interner), + binders: receiver_ty.binders.clone(), + }; + + iterate_method_candidates_by_receiver( + &refed, + first_adjustment.with_autoref(Mutability::Not), + db, + env.clone(), + traits_in_scope, + visible_from_module, + name, + &mut callback, + )?; + + let ref_muted = Canonical { + value: TyKind::Ref(Mutability::Mut, static_lifetime(), receiver_ty.value.clone()) + .intern(Interner), + binders: receiver_ty.binders.clone(), + }; + + iterate_method_candidates_by_receiver( + &ref_muted, + first_adjustment.with_autoref(Mutability::Mut), + db, + env, + traits_in_scope, + visible_from_module, + name, + &mut callback, + ) +} + +fn iterate_method_candidates_by_receiver( + receiver_ty: &Canonical<Ty>, + receiver_adjustments: ReceiverAdjustments, + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + traits_in_scope: &FxHashSet<TraitId>, + visible_from_module: VisibleFromModule, + name: Option<&Name>, + mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, +) -> ControlFlow<()> { + let mut table = InferenceTable::new(db, env); + let receiver_ty = table.instantiate_canonical(receiver_ty.clone()); + let snapshot = table.snapshot(); + // We're looking for methods with *receiver* type receiver_ty. These could + // be found in any of the derefs of receiver_ty, so we have to go through + // that. + let mut autoderef = autoderef::Autoderef::new(&mut table, receiver_ty.clone()); + while let Some((self_ty, _)) = autoderef.next() { + iterate_inherent_methods( + &self_ty, + &mut autoderef.table, + name, + Some(&receiver_ty), + Some(receiver_adjustments.clone()), + visible_from_module, + &mut callback, + )? + } + + table.rollback_to(snapshot); + + let mut autoderef = autoderef::Autoderef::new(&mut table, receiver_ty.clone()); + while let Some((self_ty, _)) = autoderef.next() { + iterate_trait_method_candidates( + &self_ty, + &mut autoderef.table, + traits_in_scope, + name, + Some(&receiver_ty), + Some(receiver_adjustments.clone()), + &mut callback, + )? + } + + ControlFlow::Continue(()) +} + +fn iterate_method_candidates_for_self_ty( + self_ty: &Canonical<Ty>, + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + traits_in_scope: &FxHashSet<TraitId>, + visible_from_module: VisibleFromModule, + name: Option<&Name>, + mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, +) -> ControlFlow<()> { + let mut table = InferenceTable::new(db, env); + let self_ty = table.instantiate_canonical(self_ty.clone()); + iterate_inherent_methods( + &self_ty, + &mut table, + name, + None, + None, + visible_from_module, + &mut callback, + )?; + iterate_trait_method_candidates( + &self_ty, + &mut table, + traits_in_scope, + name, + None, + None, + callback, + ) +} + +fn iterate_trait_method_candidates( + self_ty: &Ty, + table: &mut InferenceTable, + traits_in_scope: &FxHashSet<TraitId>, + name: Option<&Name>, + receiver_ty: Option<&Ty>, + receiver_adjustments: Option<ReceiverAdjustments>, + callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, +) -> ControlFlow<()> { + let db = table.db; + let env = table.trait_env.clone(); + let self_is_array = matches!(self_ty.kind(Interner), chalk_ir::TyKind::Array(..)); + // if ty is `dyn Trait`, the trait doesn't need to be in scope + let inherent_trait = + self_ty.dyn_trait().into_iter().flat_map(|t| all_super_traits(db.upcast(), t)); + let env_traits = matches!(self_ty.kind(Interner), TyKind::Placeholder(_)) + // if we have `T: Trait` in the param env, the trait doesn't need to be in scope + .then(|| { + env.traits_in_scope_from_clauses(self_ty.clone()) + .flat_map(|t| all_super_traits(db.upcast(), t)) + }) + .into_iter() + .flatten(); + let traits = inherent_trait.chain(env_traits).chain(traits_in_scope.iter().copied()); + + let canonical_self_ty = table.canonicalize(self_ty.clone()).value; + + 'traits: for t in traits { + let data = db.trait_data(t); + + // Traits annotated with `#[rustc_skip_array_during_method_dispatch]` are skipped during + // method resolution, if the receiver is an array, and we're compiling for editions before + // 2021. + // This is to make `[a].into_iter()` not break code with the new `IntoIterator` impl for + // arrays. + if data.skip_array_during_method_dispatch && self_is_array { + // FIXME: this should really be using the edition of the method name's span, in case it + // comes from a macro + if db.crate_graph()[env.krate].edition < Edition::Edition2021 { + continue; + } + } + + // we'll be lazy about checking whether the type implements the + // trait, but if we find out it doesn't, we'll skip the rest of the + // iteration + let mut known_implemented = false; + for &(_, item) in data.items.iter() { + // Don't pass a `visible_from_module` down to `is_valid_candidate`, + // since only inherent methods should be included into visibility checking. + if !is_valid_candidate(table, name, receiver_ty, item, self_ty, None) { + continue; + } + if !known_implemented { + let goal = generic_implements_goal(db, env.clone(), t, &canonical_self_ty); + if db.trait_solve(env.krate, goal.cast(Interner)).is_none() { + continue 'traits; + } + } + known_implemented = true; + callback(receiver_adjustments.clone().unwrap_or_default(), item)?; + } + } + ControlFlow::Continue(()) +} + +fn iterate_inherent_methods( + self_ty: &Ty, + table: &mut InferenceTable, + name: Option<&Name>, + receiver_ty: Option<&Ty>, + receiver_adjustments: Option<ReceiverAdjustments>, + visible_from_module: VisibleFromModule, + callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, +) -> ControlFlow<()> { + let db = table.db; + let env = table.trait_env.clone(); + let def_crates = match def_crates(db, self_ty, env.krate) { + Some(k) => k, + None => return ControlFlow::Continue(()), + }; + + let (module, block) = match visible_from_module { + VisibleFromModule::Filter(module) => (Some(module), module.containing_block()), + VisibleFromModule::IncludeBlock(block) => (None, Some(block)), + VisibleFromModule::None => (None, None), + }; + + if let Some(block_id) = block { + if let Some(impls) = db.inherent_impls_in_block(block_id) { + impls_for_self_ty( + &impls, + self_ty, + table, + name, + receiver_ty, + receiver_adjustments.clone(), + module, + callback, + )?; + } + } + + for krate in def_crates { + let impls = db.inherent_impls_in_crate(krate); + impls_for_self_ty( + &impls, + self_ty, + table, + name, + receiver_ty, + receiver_adjustments.clone(), + module, + callback, + )?; + } + return ControlFlow::Continue(()); + + fn impls_for_self_ty( + impls: &InherentImpls, + self_ty: &Ty, + table: &mut InferenceTable, + name: Option<&Name>, + receiver_ty: Option<&Ty>, + receiver_adjustments: Option<ReceiverAdjustments>, + visible_from_module: Option<ModuleId>, + callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, + ) -> ControlFlow<()> { + let db = table.db; + let impls_for_self_ty = impls.for_self_ty(self_ty); + for &impl_def in impls_for_self_ty { + for &item in &db.impl_data(impl_def).items { + if !is_valid_candidate(table, name, receiver_ty, item, self_ty, visible_from_module) + { + continue; + } + callback(receiver_adjustments.clone().unwrap_or_default(), item)?; + } + } + ControlFlow::Continue(()) + } +} + +/// Returns the receiver type for the index trait call. +pub fn resolve_indexing_op( + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + ty: Canonical<Ty>, + index_trait: TraitId, +) -> Option<ReceiverAdjustments> { + let mut table = InferenceTable::new(db, env.clone()); + let ty = table.instantiate_canonical(ty); + let (deref_chain, adj) = autoderef_method_receiver(&mut table, ty); + for (ty, adj) in deref_chain.into_iter().zip(adj) { + let goal = generic_implements_goal(db, env.clone(), index_trait, &ty); + if db.trait_solve(env.krate, goal.cast(Interner)).is_some() { + return Some(adj); + } + } + None +} + +fn is_valid_candidate( + table: &mut InferenceTable, + name: Option<&Name>, + receiver_ty: Option<&Ty>, + item: AssocItemId, + self_ty: &Ty, + visible_from_module: Option<ModuleId>, +) -> bool { + let db = table.db; + match item { + AssocItemId::FunctionId(m) => { + let data = db.function_data(m); + if let Some(name) = name { + if &data.name != name { + return false; + } + } + table.run_in_snapshot(|table| { + let subst = TyBuilder::subst_for_def(db, m).fill_with_inference_vars(table).build(); + let expected_self_ty = match m.lookup(db.upcast()).container { + ItemContainerId::TraitId(_) => { + subst.at(Interner, 0).assert_ty_ref(Interner).clone() + } + ItemContainerId::ImplId(impl_id) => { + subst.apply(db.impl_self_ty(impl_id).skip_binders().clone(), Interner) + } + // We should only get called for associated items (impl/trait) + ItemContainerId::ModuleId(_) | ItemContainerId::ExternBlockId(_) => { + unreachable!() + } + }; + if !table.unify(&expected_self_ty, &self_ty) { + return false; + } + if let Some(receiver_ty) = receiver_ty { + if !data.has_self_param() { + return false; + } + + let sig = db.callable_item_signature(m.into()); + let expected_receiver = + sig.map(|s| s.params()[0].clone()).substitute(Interner, &subst); + let receiver_matches = table.unify(&receiver_ty, &expected_receiver); + + if !receiver_matches { + return false; + } + } + if let Some(from_module) = visible_from_module { + if !db.function_visibility(m).is_visible_from(db.upcast(), from_module) { + cov_mark::hit!(autoderef_candidate_not_visible); + return false; + } + } + + true + }) + } + AssocItemId::ConstId(c) => { + let data = db.const_data(c); + if receiver_ty.is_some() { + return false; + } + if let Some(name) = name { + if data.name.as_ref() != Some(name) { + return false; + } + } + if let Some(from_module) = visible_from_module { + if !db.const_visibility(c).is_visible_from(db.upcast(), from_module) { + cov_mark::hit!(const_candidate_not_visible); + return false; + } + } + if let ItemContainerId::ImplId(impl_id) = c.lookup(db.upcast()).container { + let self_ty_matches = table.run_in_snapshot(|table| { + let subst = + TyBuilder::subst_for_def(db, c).fill_with_inference_vars(table).build(); + let expected_self_ty = + subst.apply(db.impl_self_ty(impl_id).skip_binders().clone(), Interner); + table.unify(&expected_self_ty, &self_ty) + }); + if !self_ty_matches { + cov_mark::hit!(const_candidate_self_type_mismatch); + return false; + } + } + true + } + _ => false, + } +} + +pub fn implements_trait( + ty: &Canonical<Ty>, + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + trait_: TraitId, +) -> bool { + let goal = generic_implements_goal(db, env.clone(), trait_, ty); + let solution = db.trait_solve(env.krate, goal.cast(Interner)); + + solution.is_some() +} + +pub fn implements_trait_unique( + ty: &Canonical<Ty>, + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + trait_: TraitId, +) -> bool { + let goal = generic_implements_goal(db, env.clone(), trait_, ty); + let solution = db.trait_solve(env.krate, goal.cast(Interner)); + + matches!(solution, Some(crate::Solution::Unique(_))) +} + +/// This creates Substs for a trait with the given Self type and type variables +/// for all other parameters, to query Chalk with it. +fn generic_implements_goal( + db: &dyn HirDatabase, + env: Arc<TraitEnvironment>, + trait_: TraitId, + self_ty: &Canonical<Ty>, +) -> Canonical<InEnvironment<super::DomainGoal>> { + let mut kinds = self_ty.binders.interned().to_vec(); + let trait_ref = TyBuilder::trait_ref(db, trait_) + .push(self_ty.value.clone()) + .fill_with_bound_vars(DebruijnIndex::INNERMOST, kinds.len()) + .build(); + kinds.extend(trait_ref.substitution.iter(Interner).skip(1).map(|x| { + let vk = match x.data(Interner) { + chalk_ir::GenericArgData::Ty(_) => { + chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General) + } + chalk_ir::GenericArgData::Lifetime(_) => chalk_ir::VariableKind::Lifetime, + chalk_ir::GenericArgData::Const(c) => { + chalk_ir::VariableKind::Const(c.data(Interner).ty.clone()) + } + }; + chalk_ir::WithKind::new(vk, UniverseIndex::ROOT) + })); + let obligation = trait_ref.cast(Interner); + Canonical { + binders: CanonicalVarKinds::from_iter(Interner, kinds), + value: InEnvironment::new(&env.env, obligation), + } +} + +fn autoderef_method_receiver( + table: &mut InferenceTable, + ty: Ty, +) -> (Vec<Canonical<Ty>>, Vec<ReceiverAdjustments>) { + let (mut deref_chain, mut adjustments): (Vec<_>, Vec<_>) = (Vec::new(), Vec::new()); + let mut autoderef = autoderef::Autoderef::new(table, ty); + while let Some((ty, derefs)) = autoderef.next() { + deref_chain.push(autoderef.table.canonicalize(ty).value); + adjustments.push(ReceiverAdjustments { + autoref: None, + autoderefs: derefs, + unsize_array: false, + }); + } + // As a last step, we can do array unsizing (that's the only unsizing that rustc does for method receivers!) + if let (Some((TyKind::Array(parameters, _), binders)), Some(adj)) = ( + deref_chain.last().map(|ty| (ty.value.kind(Interner), ty.binders.clone())), + adjustments.last().cloned(), + ) { + let unsized_ty = TyKind::Slice(parameters.clone()).intern(Interner); + deref_chain.push(Canonical { value: unsized_ty, binders }); + adjustments.push(ReceiverAdjustments { unsize_array: true, ..adj }); + } + (deref_chain, adjustments) +} |