From 6a77ec7bbe6ddbf663dce9529d11d1bb56c5489a Mon Sep 17 00:00:00 2001 From: Aleksey Kladov Date: Thu, 13 Aug 2020 16:35:29 +0200 Subject: Rename ra_hir_ty -> hir_ty --- crates/hir_ty/src/method_resolution.rs | 769 +++++++++++++++++++++++++++++++++ 1 file changed, 769 insertions(+) create mode 100644 crates/hir_ty/src/method_resolution.rs (limited to 'crates/hir_ty/src/method_resolution.rs') diff --git a/crates/hir_ty/src/method_resolution.rs b/crates/hir_ty/src/method_resolution.rs new file mode 100644 index 000000000..ec59145c7 --- /dev/null +++ b/crates/hir_ty/src/method_resolution.rs @@ -0,0 +1,769 @@ +//! 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, sync::Arc}; + +use arrayvec::ArrayVec; +use base_db::CrateId; +use hir_def::{ + builtin_type::{IntBitness, Signedness}, + lang_item::LangItemTarget, + type_ref::Mutability, + AssocContainerId, AssocItemId, FunctionId, HasModule, ImplId, Lookup, TraitId, +}; +use hir_expand::name::Name; +use rustc_hash::{FxHashMap, FxHashSet}; + +use super::Substs; +use crate::{ + autoderef, + db::HirDatabase, + primitive::{FloatBitness, FloatTy, IntTy}, + utils::all_super_traits, + ApplicationTy, Canonical, DebruijnIndex, InEnvironment, TraitEnvironment, TraitRef, Ty, TyKind, + TypeCtor, TypeWalk, +}; + +/// This is used as a key for indexing impls. +#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)] +pub enum TyFingerprint { + Apply(TypeCtor), +} + +impl TyFingerprint { + /// Creates a TyFingerprint for looking up an impl. Only certain types can + /// have 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(crate) fn for_impl(ty: &Ty) -> Option { + match ty { + Ty::Apply(a_ty) => Some(TyFingerprint::Apply(a_ty.ctor)), + _ => None, + } + } +} + +pub(crate) const ALL_INT_FPS: [TyFingerprint; 12] = [ + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Unsigned, + bitness: IntBitness::X8, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Unsigned, + bitness: IntBitness::X16, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Unsigned, + bitness: IntBitness::X32, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Unsigned, + bitness: IntBitness::X64, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Unsigned, + bitness: IntBitness::X128, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Unsigned, + bitness: IntBitness::Xsize, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Signed, + bitness: IntBitness::X8, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Signed, + bitness: IntBitness::X16, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Signed, + bitness: IntBitness::X32, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Signed, + bitness: IntBitness::X64, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Signed, + bitness: IntBitness::X128, + })), + TyFingerprint::Apply(TypeCtor::Int(IntTy { + signedness: Signedness::Signed, + bitness: IntBitness::Xsize, + })), +]; + +pub(crate) const ALL_FLOAT_FPS: [TyFingerprint; 2] = [ + TyFingerprint::Apply(TypeCtor::Float(FloatTy { bitness: FloatBitness::X32 })), + TyFingerprint::Apply(TypeCtor::Float(FloatTy { bitness: FloatBitness::X64 })), +]; + +/// 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); + for (_module_id, module_data) in crate_def_map.modules.iter() { + for impl_id in module_data.scope.impls() { + let target_trait = match db.impl_trait(impl_id) { + Some(tr) => tr.value.trait_, + None => continue, + }; + let self_ty = db.impl_self_ty(impl_id); + let self_ty_fp = TyFingerprint::for_impl(&self_ty.value); + impls + .map + .entry(target_trait) + .or_default() + .entry(self_ty_fp) + .or_default() + .push(impl_id); + } + } + + 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)); + } + + Arc::new(res) + } + + 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 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 map: FxHashMap<_, Vec<_>> = FxHashMap::default(); + + let crate_def_map = db.crate_def_map(krate); + for (_module_id, module_data) in crate_def_map.modules.iter() { + 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); + if let Some(fp) = TyFingerprint::for_impl(&self_ty.value) { + map.entry(fp).or_default().push(impl_id); + } + } + } + + Arc::new(Self { map }) + } + + pub fn for_self_ty(&self, self_ty: &Ty) -> &[ImplId] { + match TyFingerprint::for_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()) + } +} + +impl Ty { + pub fn def_crates( + &self, + db: &dyn HirDatabase, + 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::<[LangItemTarget; 2]>::new(); + $( + v.extend(db.lang_item(cur_crate, $name.into())); + )+ + v + }}; + } + + let lang_item_targets = match self { + Ty::Apply(a_ty) => match a_ty.ctor { + TypeCtor::Adt(def_id) => { + return Some(std::iter::once(def_id.module(db.upcast()).krate).collect()) + } + TypeCtor::Bool => lang_item_crate!("bool"), + TypeCtor::Char => lang_item_crate!("char"), + TypeCtor::Float(f) => match f.bitness { + // There are two lang items: one in libcore (fXX) and one in libstd (fXX_runtime) + FloatBitness::X32 => lang_item_crate!("f32", "f32_runtime"), + FloatBitness::X64 => lang_item_crate!("f64", "f64_runtime"), + }, + TypeCtor::Int(i) => lang_item_crate!(i.ty_to_string()), + TypeCtor::Str => lang_item_crate!("str_alloc", "str"), + TypeCtor::Slice => lang_item_crate!("slice_alloc", "slice"), + TypeCtor::RawPtr(Mutability::Shared) => lang_item_crate!("const_ptr"), + TypeCtor::RawPtr(Mutability::Mut) => lang_item_crate!("mut_ptr"), + _ => return None, + }, + _ => 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.module(db.upcast()).krate) + .collect(); + Some(res) + } +} +/// Look up the method with the given name, returning the actual autoderefed +/// receiver type (but without autoref applied yet). +pub(crate) fn lookup_method( + ty: &Canonical, + db: &dyn HirDatabase, + env: Arc, + krate: CrateId, + traits_in_scope: &FxHashSet, + name: &Name, +) -> Option<(Ty, FunctionId)> { + iterate_method_candidates( + ty, + db, + env, + krate, + &traits_in_scope, + Some(name), + LookupMode::MethodCall, + |ty, f| match f { + AssocItemId::FunctionId(f) => Some((ty.clone(), 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, +} + +// 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 fn iterate_method_candidates( + ty: &Canonical, + db: &dyn HirDatabase, + env: Arc, + krate: CrateId, + traits_in_scope: &FxHashSet, + name: Option<&Name>, + mode: LookupMode, + mut callback: impl FnMut(&Ty, AssocItemId) -> Option, +) -> Option { + let mut slot = None; + iterate_method_candidates_impl( + ty, + db, + env, + krate, + traits_in_scope, + name, + mode, + &mut |ty, item| { + assert!(slot.is_none()); + slot = callback(ty, item); + slot.is_some() + }, + ); + slot +} + +fn iterate_method_candidates_impl( + ty: &Canonical, + db: &dyn HirDatabase, + env: Arc, + krate: CrateId, + traits_in_scope: &FxHashSet, + name: Option<&Name>, + mode: LookupMode, + callback: &mut dyn FnMut(&Ty, AssocItemId) -> bool, +) -> bool { + 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). We just ignore + // the autoref currently -- when we find a method matching the given name, + // we assume it fits. + + // Also 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). + let ty = InEnvironment { value: ty.clone(), environment: env.clone() }; + + // 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 deref_chain = autoderef_method_receiver(db, krate, ty); + for i in 0..deref_chain.len() { + if iterate_method_candidates_with_autoref( + &deref_chain[i..], + db, + env.clone(), + krate, + traits_in_scope, + name, + callback, + ) { + return true; + } + } + false + } + LookupMode::Path => { + // No autoderef for path lookups + iterate_method_candidates_for_self_ty( + &ty, + db, + env, + krate, + traits_in_scope, + name, + callback, + ) + } + } +} + +fn iterate_method_candidates_with_autoref( + deref_chain: &[Canonical], + db: &dyn HirDatabase, + env: Arc, + krate: CrateId, + traits_in_scope: &FxHashSet, + name: Option<&Name>, + mut callback: &mut dyn FnMut(&Ty, AssocItemId) -> bool, +) -> bool { + if iterate_method_candidates_by_receiver( + &deref_chain[0], + &deref_chain[1..], + db, + env.clone(), + krate, + &traits_in_scope, + name, + &mut callback, + ) { + return true; + } + let refed = Canonical { + kinds: deref_chain[0].kinds.clone(), + value: Ty::apply_one(TypeCtor::Ref(Mutability::Shared), deref_chain[0].value.clone()), + }; + if iterate_method_candidates_by_receiver( + &refed, + deref_chain, + db, + env.clone(), + krate, + &traits_in_scope, + name, + &mut callback, + ) { + return true; + } + let ref_muted = Canonical { + kinds: deref_chain[0].kinds.clone(), + value: Ty::apply_one(TypeCtor::Ref(Mutability::Mut), deref_chain[0].value.clone()), + }; + if iterate_method_candidates_by_receiver( + &ref_muted, + deref_chain, + db, + env, + krate, + &traits_in_scope, + name, + &mut callback, + ) { + return true; + } + false +} + +fn iterate_method_candidates_by_receiver( + receiver_ty: &Canonical, + rest_of_deref_chain: &[Canonical], + db: &dyn HirDatabase, + env: Arc, + krate: CrateId, + traits_in_scope: &FxHashSet, + name: Option<&Name>, + mut callback: &mut dyn FnMut(&Ty, AssocItemId) -> bool, +) -> bool { + // 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 std::iter::once(receiver_ty).chain(rest_of_deref_chain) { + if iterate_inherent_methods(self_ty, db, name, Some(receiver_ty), krate, &mut callback) { + return true; + } + } + for self_ty in std::iter::once(receiver_ty).chain(rest_of_deref_chain) { + if iterate_trait_method_candidates( + self_ty, + db, + env.clone(), + krate, + &traits_in_scope, + name, + Some(receiver_ty), + &mut callback, + ) { + return true; + } + } + false +} + +fn iterate_method_candidates_for_self_ty( + self_ty: &Canonical, + db: &dyn HirDatabase, + env: Arc, + krate: CrateId, + traits_in_scope: &FxHashSet, + name: Option<&Name>, + mut callback: &mut dyn FnMut(&Ty, AssocItemId) -> bool, +) -> bool { + if iterate_inherent_methods(self_ty, db, name, None, krate, &mut callback) { + return true; + } + iterate_trait_method_candidates(self_ty, db, env, krate, traits_in_scope, name, None, callback) +} + +fn iterate_trait_method_candidates( + self_ty: &Canonical, + db: &dyn HirDatabase, + env: Arc, + krate: CrateId, + traits_in_scope: &FxHashSet, + name: Option<&Name>, + receiver_ty: Option<&Canonical>, + callback: &mut dyn FnMut(&Ty, AssocItemId) -> bool, +) -> bool { + // 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 = if let Ty::Placeholder(_) = self_ty.value { + // if we have `T: Trait` in the param env, the trait doesn't need to be in scope + env.trait_predicates_for_self_ty(&self_ty.value) + .map(|tr| tr.trait_) + .flat_map(|t| all_super_traits(db.upcast(), t)) + .collect() + } else { + Vec::new() + }; + let traits = + inherent_trait.chain(env_traits.into_iter()).chain(traits_in_scope.iter().copied()); + 'traits: for t in traits { + let data = db.trait_data(t); + + // 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 (_name, item) in data.items.iter() { + if !is_valid_candidate(db, name, receiver_ty, *item, self_ty) { + continue; + } + if !known_implemented { + let goal = generic_implements_goal(db, env.clone(), t, self_ty.clone()); + if db.trait_solve(krate, goal).is_none() { + continue 'traits; + } + } + known_implemented = true; + if callback(&self_ty.value, *item) { + return true; + } + } + } + false +} + +fn iterate_inherent_methods( + self_ty: &Canonical, + db: &dyn HirDatabase, + name: Option<&Name>, + receiver_ty: Option<&Canonical>, + krate: CrateId, + callback: &mut dyn FnMut(&Ty, AssocItemId) -> bool, +) -> bool { + let def_crates = match self_ty.value.def_crates(db, krate) { + Some(k) => k, + None => return false, + }; + for krate in def_crates { + let impls = db.inherent_impls_in_crate(krate); + + for &impl_def in impls.for_self_ty(&self_ty.value) { + for &item in db.impl_data(impl_def).items.iter() { + if !is_valid_candidate(db, name, receiver_ty, item, self_ty) { + 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, impl_def, self_ty).is_none() { + test_utils::mark::hit!(impl_self_type_match_without_receiver); + continue; + } + if callback(&self_ty.value, item) { + return true; + } + } + } + } + false +} + +/// Returns the self type for the index trait call. +pub fn resolve_indexing_op( + db: &dyn HirDatabase, + ty: &Canonical, + env: Arc, + krate: CrateId, + index_trait: TraitId, +) -> Option> { + let ty = InEnvironment { value: ty.clone(), environment: env.clone() }; + let deref_chain = autoderef_method_receiver(db, krate, ty); + for ty in deref_chain { + let goal = generic_implements_goal(db, env.clone(), index_trait, ty.clone()); + if db.trait_solve(krate, goal).is_some() { + return Some(ty); + } + } + None +} + +fn is_valid_candidate( + db: &dyn HirDatabase, + name: Option<&Name>, + receiver_ty: Option<&Canonical>, + item: AssocItemId, + self_ty: &Canonical, +) -> 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, m, self_ty) { + Some(ty) => ty, + None => return false, + }; + if transformed_receiver_ty != receiver_ty.value { + 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, + 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 vars = Substs::build_for_def(db, impl_id) + .fill_with_bound_vars(DebruijnIndex::INNERMOST, self_ty.kinds.len()) + .build(); + let self_ty_with_vars = db.impl_self_ty(impl_id).subst(&vars); + let mut kinds = self_ty.kinds.to_vec(); + kinds.extend(iter::repeat(TyKind::General).take(vars.len())); + let tys = Canonical { kinds: kinds.into(), value: (self_ty_with_vars, self_ty.value.clone()) }; + let substs = super::infer::unify(&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. + substs.map(|s| fallback_bound_vars(s.suffix(vars.len()), self_ty.kinds.len())) +} + +/// This replaces any 'free' Bound vars in `s` (i.e. those with indices past +/// num_vars_to_keep) by `Ty::Unknown`. +fn fallback_bound_vars(s: Substs, num_vars_to_keep: usize) -> Substs { + s.fold_binders( + &mut |ty, binders| { + if let Ty::Bound(bound) = &ty { + if bound.index >= num_vars_to_keep && bound.debruijn >= binders { + Ty::Unknown + } else { + ty + } + } else { + ty + } + }, + DebruijnIndex::INNERMOST, + ) +} + +fn transform_receiver_ty( + db: &dyn HirDatabase, + function_id: FunctionId, + self_ty: &Canonical, +) -> Option { + let substs = match function_id.lookup(db.upcast()).container { + AssocContainerId::TraitId(_) => Substs::build_for_def(db, function_id) + .push(self_ty.value.clone()) + .fill_with_unknown() + .build(), + AssocContainerId::ImplId(impl_id) => inherent_impl_substs(db, impl_id, &self_ty)?, + AssocContainerId::ContainerId(_) => unreachable!(), + }; + let sig = db.callable_item_signature(function_id.into()); + Some(sig.value.params()[0].clone().subst_bound_vars(&substs)) +} + +pub fn implements_trait( + ty: &Canonical, + db: &dyn HirDatabase, + env: Arc, + krate: CrateId, + trait_: TraitId, +) -> bool { + let goal = generic_implements_goal(db, env, trait_, ty.clone()); + let solution = db.trait_solve(krate, goal); + + solution.is_some() +} + +/// 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.kinds.to_vec(); + let substs = super::Substs::build_for_def(db, trait_) + .push(self_ty.value) + .fill_with_bound_vars(DebruijnIndex::INNERMOST, kinds.len()) + .build(); + kinds.extend(iter::repeat(TyKind::General).take(substs.len() - 1)); + let trait_ref = TraitRef { trait_, substs }; + let obligation = super::Obligation::Trait(trait_ref); + Canonical { kinds: kinds.into(), value: InEnvironment::new(env, obligation) } +} + +fn autoderef_method_receiver( + db: &dyn HirDatabase, + krate: CrateId, + ty: InEnvironment>, +) -> Vec> { + let mut deref_chain: Vec<_> = autoderef::autoderef(db, Some(krate), ty).collect(); + // As a last step, we can do array unsizing (that's the only unsizing that rustc does for method receivers!) + if let Some(Ty::Apply(ApplicationTy { ctor: TypeCtor::Array, parameters })) = + deref_chain.last().map(|ty| &ty.value) + { + let kinds = deref_chain.last().unwrap().kinds.clone(); + let unsized_ty = Ty::apply(TypeCtor::Slice, parameters.clone()); + deref_chain.push(Canonical { value: unsized_ty, kinds }) + } + deref_chain +} -- cgit v1.2.3