//! 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, lang_item::LangItemTarget, 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}, consteval::{self, ConstExt}, db::HirDatabase, from_foreign_def_id, infer::{unify::InferenceTable, Adjust, Adjustment, AutoBorrow, OverloadedDeref, PointerCast}, primitive::{self, FloatTy, IntTy, UintTy}, static_lifetime, utils::all_super_traits, AdtId, Canonical, CanonicalVarKinds, DebruijnIndex, ForeignDefId, InEnvironment, Interner, Scalar, Substitution, 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 { 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 { 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` is `None`, the impl may apply to any self type. map: FxHashMap, Vec>>, } impl TraitImpls { pub(crate) fn trait_impls_in_crate_query(db: &dyn HirDatabase, krate: CrateId) -> Arc { 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> { 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 { 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 + '_ { 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 + '_ { 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 + '_ { 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 + '_ { 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>, } impl InherentImpls { pub(crate) fn inherent_impls_in_crate_query(db: &dyn HirDatabase, krate: CrateId) -> Arc { 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(); return Arc::new(impls); } pub(crate) fn inherent_impls_in_block_query( db: &dyn HirDatabase, block: BlockId, ) -> Option> { 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)); } return 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 + '_ { self.map.values().flat_map(|v| v.iter().copied()) } } fn collect_unnamed_consts<'a>( db: &'a dyn HirDatabase, scope: &'a ItemScope, ) -> impl Iterator + '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> { // Types like slice can have inherent impls in several crates, (core and alloc). // The corresponding impls are marked with lang items, so we can use them to find the required crates. macro_rules! lang_item_crate { ($($name:expr),+ $(,)?) => {{ let mut v = ArrayVec::::new(); $( v.extend(db.lang_item(cur_crate, $name.into())); )+ v }}; } let mod_to_crate_ids = |module: ModuleId| Some(iter::once(module.krate()).collect()); let lang_item_targets = match ty.kind(Interner) { TyKind::Adt(AdtId(def_id), _) => { return mod_to_crate_ids(def_id.module(db.upcast())); } TyKind::Foreign(id) => { return mod_to_crate_ids( from_foreign_def_id(*id).lookup(db.upcast()).module(db.upcast()), ); } TyKind::Scalar(Scalar::Bool) => lang_item_crate!("bool"), TyKind::Scalar(Scalar::Char) => lang_item_crate!("char"), TyKind::Scalar(Scalar::Float(f)) => match f { // There are two lang items: one in libcore (fXX) and one in libstd (fXX_runtime) FloatTy::F32 => lang_item_crate!("f32", "f32_runtime"), FloatTy::F64 => lang_item_crate!("f64", "f64_runtime"), }, &TyKind::Scalar(Scalar::Int(t)) => { lang_item_crate!(primitive::int_ty_to_string(t)) } &TyKind::Scalar(Scalar::Uint(t)) => { lang_item_crate!(primitive::uint_ty_to_string(t)) } TyKind::Str => lang_item_crate!("str_alloc", "str"), TyKind::Slice(_) => lang_item_crate!("slice_alloc", "slice"), TyKind::Array(..) => lang_item_crate!("array"), TyKind::Raw(Mutability::Not, _) => lang_item_crate!("const_ptr"), TyKind::Raw(Mutability::Mut, _) => lang_item_crate!("mut_ptr"), TyKind::Dyn(_) => { return ty.dyn_trait().and_then(|trait_| { mod_to_crate_ids(GenericDefId::TraitId(trait_).module(db.upcast())) }); } _ => return None, }; let res = lang_item_targets .into_iter() .filter_map(|it| match it { LangItemTarget::ImplDefId(it) => Some(it), _ => None, }) .map(|it| it.lookup(db.upcast()).container.krate()) .collect(); Some(res) } /// Look up the method with the given name. pub(crate) fn lookup_method( ty: &Canonical, db: &dyn HirDatabase, env: Arc, traits_in_scope: &FxHashSet, 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> for VisibleFromModule { fn from(module: Option) -> Self { match module { Some(module) => Self::Filter(module), None => Self::None, } } } impl From> for VisibleFromModule { fn from(block: Option) -> Self { match block { Some(block) => Self::IncludeBlock(block), None => Self::None, } } } #[derive(Debug, Clone, Default)] pub struct ReceiverAdjustments { autoref: Option, autoderefs: usize, unsize_array: bool, } impl ReceiverAdjustments { pub(crate) fn apply(&self, table: &mut InferenceTable, ty: Ty) -> (Ty, Vec) { 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( ty: &Canonical, db: &dyn HirDatabase, env: Arc, traits_in_scope: &FxHashSet, visible_from_module: VisibleFromModule, name: Option<&Name>, mode: LookupMode, mut callback: impl FnMut(ReceiverAdjustments, AssocItemId) -> Option, ) -> Option { 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, db: &dyn HirDatabase, env: Arc, traits_in_scope: &FxHashSet, 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, db: &dyn HirDatabase, env: Arc, traits_in_scope: &FxHashSet, 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 deref_chains = stdx::slice_tails(&deref_chain); let result = deref_chains.zip(adj).try_for_each(|(deref_chain, adj)| { iterate_method_candidates_with_autoref( deref_chain, 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.clone(), traits_in_scope, visible_from_module, name, callback, ) } } } fn iterate_method_candidates_with_autoref( deref_chain: &[Canonical], first_adjustment: ReceiverAdjustments, db: &dyn HirDatabase, env: Arc, traits_in_scope: &FxHashSet, visible_from_module: VisibleFromModule, name: Option<&Name>, mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, ) -> ControlFlow<()> { let (receiver_ty, rest) = match deref_chain.split_first() { Some((rec, rest)) => (rec, rest), None => { never!("received empty deref-chain"); return ControlFlow::Break(()); } }; iterate_method_candidates_by_receiver( receiver_ty, first_adjustment.clone(), rest, 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), deref_chain, 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), deref_chain, db, env.clone(), traits_in_scope, visible_from_module, name, &mut callback, ) } fn iterate_method_candidates_by_receiver( receiver_ty: &Canonical, receiver_adjustments: ReceiverAdjustments, rest_of_deref_chain: &[Canonical], db: &dyn HirDatabase, env: Arc, traits_in_scope: &FxHashSet, visible_from_module: VisibleFromModule, name: Option<&Name>, mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, ) -> ControlFlow<()> { // 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. for self_ty in iter::once(receiver_ty).chain(rest_of_deref_chain) { iterate_inherent_methods( self_ty, db, env.clone(), name, Some(receiver_ty), Some(receiver_adjustments.clone()), visible_from_module, &mut callback, )? } for self_ty in iter::once(receiver_ty).chain(rest_of_deref_chain) { iterate_trait_method_candidates( self_ty, db, env.clone(), 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, db: &dyn HirDatabase, env: Arc, traits_in_scope: &FxHashSet, visible_from_module: VisibleFromModule, name: Option<&Name>, mut callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, ) -> ControlFlow<()> { iterate_inherent_methods( self_ty, db, env.clone(), name, None, None, visible_from_module, &mut callback, )?; iterate_trait_method_candidates(self_ty, db, env, traits_in_scope, name, None, None, callback) } fn iterate_trait_method_candidates( self_ty: &Canonical, db: &dyn HirDatabase, env: Arc, traits_in_scope: &FxHashSet, name: Option<&Name>, receiver_ty: Option<&Canonical>, receiver_adjustments: Option, callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, ) -> ControlFlow<()> { let self_is_array = matches!(self_ty.value.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.value.dyn_trait().into_iter().flat_map(|t| all_super_traits(db.upcast(), t)); let env_traits = matches!(self_ty.value.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.value.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()); '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(db, env.clone(), name, receiver_ty, item, self_ty, None) { continue; } if !known_implemented { let goal = generic_implements_goal(db, env.clone(), t, 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 filter_inherent_impls_for_self_ty<'i>( impls: &'i InherentImpls, self_ty: &Ty, ) -> impl Iterator { // inherent methods on arrays are fingerprinted as [T; {unknown}], so we must also consider them when // resolving a method call on an array with a known len let array_impls = { match self_ty.kind(Interner) { TyKind::Array(parameters, array_len) if !array_len.is_unknown() => { let unknown_array_len_ty = TyKind::Array(parameters.clone(), consteval::usize_const(None)); Some(impls.for_self_ty(&unknown_array_len_ty.intern(Interner))) } _ => None, } } .into_iter() .flatten(); impls.for_self_ty(self_ty).iter().chain(array_impls) } fn iterate_inherent_methods( self_ty: &Canonical, db: &dyn HirDatabase, env: Arc, name: Option<&Name>, receiver_ty: Option<&Canonical>, receiver_adjustments: Option, visible_from_module: VisibleFromModule, callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, ) -> ControlFlow<()> { let def_crates = match def_crates(db, &self_ty.value, 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, db, env.clone(), 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, db, env.clone(), name, receiver_ty, receiver_adjustments.clone(), module, callback, )?; } return ControlFlow::Continue(()); fn impls_for_self_ty( impls: &InherentImpls, self_ty: &Canonical, db: &dyn HirDatabase, env: Arc, name: Option<&Name>, receiver_ty: Option<&Canonical>, receiver_adjustments: Option, visible_from_module: Option, callback: &mut dyn FnMut(ReceiverAdjustments, AssocItemId) -> ControlFlow<()>, ) -> ControlFlow<()> { let impls_for_self_ty = filter_inherent_impls_for_self_ty(impls, &self_ty.value); for &impl_def in impls_for_self_ty { for &item in &db.impl_data(impl_def).items { if !is_valid_candidate( db, env.clone(), name, receiver_ty, item, self_ty, visible_from_module, ) { continue; } // we have to check whether the self type unifies with the type // that the impl is for. If we have a receiver type, this // already happens in `is_valid_candidate` above; if not, we // check it here if receiver_ty.is_none() && inherent_impl_substs(db, env.clone(), impl_def, self_ty).is_none() { cov_mark::hit!(impl_self_type_match_without_receiver); 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, ty: Canonical, index_trait: TraitId, ) -> Option { 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_transformed_receiver_ty_equal(transformed_receiver_ty: &Ty, receiver_ty: &Ty) -> bool { if transformed_receiver_ty == receiver_ty { return true; } // a transformed receiver may be considered equal (and a valid method call candidate) if it is an array // with an unknown (i.e. generic) length, and the receiver is an array with the same item type but a known len, // this allows inherent methods on arrays to be considered valid resolution candidates match (transformed_receiver_ty.kind(Interner), receiver_ty.kind(Interner)) { ( TyKind::Array(transformed_array_ty, transformed_array_len), TyKind::Array(receiver_array_ty, receiver_array_len), ) if transformed_array_ty == receiver_array_ty && transformed_array_len.is_unknown() && !receiver_array_len.is_unknown() => { true } _ => false, } } fn is_valid_candidate( db: &dyn HirDatabase, env: Arc, name: Option<&Name>, receiver_ty: Option<&Canonical>, item: AssocItemId, self_ty: &Canonical, visible_from_module: Option, ) -> bool { match item { AssocItemId::FunctionId(m) => { let data = db.function_data(m); if let Some(name) = name { if &data.name != name { return false; } } if let Some(receiver_ty) = receiver_ty { if !data.has_self_param() { return false; } let transformed_receiver_ty = match transform_receiver_ty(db, env, m, self_ty) { Some(ty) => ty, None => return false, }; if !is_transformed_receiver_ty_equal(&transformed_receiver_ty, &receiver_ty.value) { 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); name.map_or(true, |name| data.name.as_ref() == Some(name)) && receiver_ty.is_none() } _ => false, } } pub(crate) fn inherent_impl_substs( db: &dyn HirDatabase, env: Arc, impl_id: ImplId, self_ty: &Canonical, ) -> Option { // we create a var for each type parameter of the impl; we need to keep in // mind here that `self_ty` might have vars of its own let self_ty_vars = self_ty.binders.len(Interner); let vars = TyBuilder::subst_for_def(db, impl_id) .fill_with_bound_vars(DebruijnIndex::INNERMOST, self_ty_vars) .build(); let self_ty_with_vars = db.impl_self_ty(impl_id).substitute(Interner, &vars); let mut kinds = self_ty.binders.interned().to_vec(); kinds.extend( iter::repeat(chalk_ir::WithKind::new( chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General), UniverseIndex::ROOT, )) .take(vars.len(Interner)), ); let tys = Canonical { binders: CanonicalVarKinds::from_iter(Interner, kinds), value: (self_ty_with_vars, self_ty.value.clone()), }; let substs = super::infer::unify(db, env, &tys)?; // We only want the substs for the vars we added, not the ones from self_ty. // Also, if any of the vars we added are still in there, we replace them by // Unknown. I think this can only really happen if self_ty contained // Unknown, and in that case we want the result to contain Unknown in those // places again. let suffix = Substitution::from_iter(Interner, substs.iter(Interner).cloned().skip(self_ty_vars)); Some(fallback_bound_vars(suffix, self_ty_vars)) } /// This replaces any 'free' Bound vars in `s` (i.e. those with indices past /// num_vars_to_keep) by `TyKind::Unknown`. fn fallback_bound_vars(s: Substitution, num_vars_to_keep: usize) -> Substitution { crate::fold_free_vars(s, |bound, binders| { if bound.index >= num_vars_to_keep && bound.debruijn == DebruijnIndex::INNERMOST { TyKind::Error.intern(Interner) } else { bound.shifted_in_from(binders).to_ty(Interner) } }) } fn transform_receiver_ty( db: &dyn HirDatabase, env: Arc, function_id: FunctionId, self_ty: &Canonical, ) -> Option { let substs = match function_id.lookup(db.upcast()).container { ItemContainerId::TraitId(_) => TyBuilder::subst_for_def(db, function_id) .push(self_ty.value.clone()) .fill_with_unknown() .build(), ItemContainerId::ImplId(impl_id) => { let impl_substs = inherent_impl_substs(db, env, impl_id, self_ty)?; TyBuilder::subst_for_def(db, function_id) .use_parent_substs(&impl_substs) .fill_with_unknown() .build() } // No receiver ItemContainerId::ModuleId(_) | ItemContainerId::ExternBlockId(_) => unreachable!(), }; let sig = db.callable_item_signature(function_id.into()); Some(sig.map(|s| s.params()[0].clone()).substitute(Interner, &substs)) } pub fn implements_trait( ty: &Canonical, db: &dyn HirDatabase, env: Arc, 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, db: &dyn HirDatabase, env: Arc, 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, trait_: TraitId, self_ty: &Canonical, ) -> Canonical> { 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( iter::repeat(chalk_ir::WithKind::new( chalk_ir::VariableKind::Ty(chalk_ir::TyVariableKind::General), UniverseIndex::ROOT, )) .take(trait_ref.substitution.len(Interner) - 1), ); 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>, Vec) { 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) }