//! This module provides the built-in trait implementations, e.g. to make
//! closures implement `Fn`.
-use hir_def::{expr::Expr, lang_item::LangItemTarget, TraitId, TypeAliasId};
+use hir_def::{expr::Expr, TraitId, TypeAliasId};
use hir_expand::name::name;
use ra_db::CrateId;
-use super::{AssocTyValue, Impl, UnsizeToSuperTraitObjectData};
+use super::{AssocTyValue, Impl};
use crate::{
- db::HirDatabase,
- utils::{all_super_traits, generics},
- ApplicationTy, Binders, BoundVar, DebruijnIndex, GenericPredicate, Substs, TraitRef, Ty,
- TypeCtor, TypeWalk,
+ db::HirDatabase, ApplicationTy, BoundVar, DebruijnIndex, Substs, TraitRef, Ty, TypeCtor,
};
pub(super) struct BuiltinImplData {
krate: CrateId,
ty: &Ty,
// The first argument for the trait, if present
- arg: &Option<Ty>,
+ _arg: &Option<Ty>,
trait_: TraitId,
mut callback: impl FnMut(Impl),
) {
}
}
}
-
- let unsize_trait = get_unsize_trait(db, krate);
- if let Some(actual_trait) = unsize_trait {
- if trait_ == actual_trait {
- get_builtin_unsize_impls(db, krate, ty, arg, callback);
- }
- }
-}
-
-fn get_builtin_unsize_impls(
- db: &dyn HirDatabase,
- krate: CrateId,
- ty: &Ty,
- // The first argument for the trait, if present
- arg: &Option<Ty>,
- mut callback: impl FnMut(Impl),
-) {
- if !check_unsize_impl_prerequisites(db, krate) {
- return;
- }
-
- if let Ty::Apply(ApplicationTy { ctor: TypeCtor::Array, .. }) = ty {
- callback(Impl::UnsizeArray);
- return; // array is unsized, the rest of the impls shouldn't apply
- }
-
- if let Some(target_trait) = arg.as_ref().and_then(|t| t.dyn_trait_ref()) {
- // FIXME what about more complicated dyn tys with marker traits?
- if let Some(trait_ref) = ty.dyn_trait_ref() {
- if trait_ref.trait_ != target_trait.trait_ {
- let super_traits = all_super_traits(db.upcast(), trait_ref.trait_);
- if super_traits.contains(&target_trait.trait_) {
- callback(Impl::UnsizeToSuperTraitObject(UnsizeToSuperTraitObjectData {
- trait_: trait_ref.trait_,
- super_trait: target_trait.trait_,
- }));
- }
- }
- } else {
- // FIXME only for sized types
- callback(Impl::UnsizeToTraitObject(target_trait.trait_));
- }
- }
}
pub(super) fn impl_datum(db: &dyn HirDatabase, krate: CrateId, impl_: Impl) -> BuiltinImplData {
match impl_ {
Impl::ImplDef(_) => unreachable!(),
Impl::ClosureFnTraitImpl(data) => closure_fn_trait_impl_datum(db, krate, data),
- Impl::UnsizeArray => array_unsize_impl_datum(db, krate),
- Impl::UnsizeToTraitObject(trait_) => trait_object_unsize_impl_datum(db, krate, trait_),
- Impl::UnsizeToSuperTraitObject(data) => {
- super_trait_object_unsize_impl_datum(db, krate, data)
- }
}
}
value: output_ty,
}
}
-
-// Array unsizing
-
-fn check_unsize_impl_prerequisites(db: &dyn HirDatabase, krate: CrateId) -> bool {
- // the Unsize trait needs to exist and have two type parameters (Self and T)
- let unsize_trait = match get_unsize_trait(db, krate) {
- Some(t) => t,
- None => return false,
- };
- let generic_params = generics(db.upcast(), unsize_trait.into());
- generic_params.len() == 2
-}
-
-fn array_unsize_impl_datum(db: &dyn HirDatabase, krate: CrateId) -> BuiltinImplData {
- // impl<T> Unsize<[T]> for [T; _]
- // (this can be a single impl because we don't distinguish array sizes currently)
-
- let trait_ = get_unsize_trait(db, krate) // get unsize trait
- // the existence of the Unsize trait has been checked before
- .expect("Unsize trait missing");
-
- let var = Ty::Bound(BoundVar::new(DebruijnIndex::INNERMOST, 0));
- let substs = Substs::builder(2)
- .push(Ty::apply_one(TypeCtor::Array, var.clone()))
- .push(Ty::apply_one(TypeCtor::Slice, var))
- .build();
-
- let trait_ref = TraitRef { trait_, substs };
-
- BuiltinImplData {
- num_vars: 1,
- trait_ref,
- where_clauses: Vec::new(),
- assoc_ty_values: Vec::new(),
- }
-}
-
-// Trait object unsizing
-
-fn trait_object_unsize_impl_datum(
- db: &dyn HirDatabase,
- krate: CrateId,
- trait_: TraitId,
-) -> BuiltinImplData {
- // impl<T, T1, ...> Unsize<dyn Trait<T1, ...>> for T where T: Trait<T1, ...>
-
- let unsize_trait = get_unsize_trait(db, krate) // get unsize trait
- // the existence of the Unsize trait has been checked before
- .expect("Unsize trait missing");
-
- let self_ty = Ty::Bound(BoundVar::new(DebruijnIndex::INNERMOST, 0));
-
- let target_substs = Substs::build_for_def(db, trait_)
- .push(Ty::Bound(BoundVar::new(DebruijnIndex::INNERMOST, 0)))
- .fill_with_bound_vars(DebruijnIndex::ONE, 1)
- .build();
- let num_vars = target_substs.len();
- let target_trait_ref = TraitRef { trait_, substs: target_substs };
- let target_bounds = vec![GenericPredicate::Implemented(target_trait_ref)];
-
- let self_substs =
- Substs::build_for_def(db, trait_).fill_with_bound_vars(DebruijnIndex::INNERMOST, 0).build();
- let self_trait_ref = TraitRef { trait_, substs: self_substs };
- let where_clauses = vec![GenericPredicate::Implemented(self_trait_ref)];
-
- let impl_substs = Substs::builder(2).push(self_ty).push(Ty::Dyn(target_bounds.into())).build();
-
- let trait_ref = TraitRef { trait_: unsize_trait, substs: impl_substs };
-
- BuiltinImplData { num_vars, trait_ref, where_clauses, assoc_ty_values: Vec::new() }
-}
-
-fn super_trait_object_unsize_impl_datum(
- db: &dyn HirDatabase,
- krate: CrateId,
- data: UnsizeToSuperTraitObjectData,
-) -> BuiltinImplData {
- // impl<T1, ...> Unsize<dyn SuperTrait> for dyn Trait<T1, ...>
-
- let unsize_trait = get_unsize_trait(db, krate) // get unsize trait
- // the existence of the Unsize trait has been checked before
- .expect("Unsize trait missing");
-
- let self_substs = Substs::build_for_def(db, data.trait_)
- .fill_with_bound_vars(DebruijnIndex::INNERMOST, 0)
- .build();
- let self_trait_ref = TraitRef { trait_: data.trait_, substs: self_substs.clone() };
-
- let num_vars = self_substs.len() - 1;
-
- // we need to go from our trait to the super trait, substituting type parameters
- let path = crate::utils::find_super_trait_path(db.upcast(), data.trait_, data.super_trait);
-
- let mut current_trait_ref = self_trait_ref.clone();
- for t in path.into_iter().skip(1) {
- let bounds = db.generic_predicates(current_trait_ref.trait_.into());
- let super_trait_ref = bounds
- .iter()
- .find_map(|b| match &b.value {
- GenericPredicate::Implemented(tr)
- if tr.trait_ == t
- && tr.substs[0]
- == Ty::Bound(BoundVar::new(DebruijnIndex::INNERMOST, 0)) =>
- {
- Some(Binders { value: tr, num_binders: b.num_binders })
- }
- _ => None,
- })
- .expect("trait bound for known super trait not found");
- current_trait_ref = super_trait_ref.cloned().subst(¤t_trait_ref.substs);
- }
-
- // We need to renumber the variables a bit now: from ^0.0, ^0.1, ^0.2, ...
- // to ^0.0, ^1.0, ^1.1. The reason for this is that the first variable comes
- // from the dyn Trait binder, while the other variables come from the impl.
- let new_substs = Substs::builder(num_vars + 1)
- .push(Ty::Bound(BoundVar::new(DebruijnIndex::INNERMOST, 0)))
- .fill_with_bound_vars(DebruijnIndex::ONE, 0)
- .build();
-
- let self_bounds =
- vec![GenericPredicate::Implemented(self_trait_ref.subst_bound_vars(&new_substs))];
- let super_bounds =
- vec![GenericPredicate::Implemented(current_trait_ref.subst_bound_vars(&new_substs))];
-
- let substs = Substs::builder(2)
- .push(Ty::Dyn(self_bounds.into()))
- .push(Ty::Dyn(super_bounds.into()))
- .build();
-
- let trait_ref = TraitRef { trait_: unsize_trait, substs };
-
- BuiltinImplData { num_vars, trait_ref, where_clauses: Vec::new(), assoc_ty_values: Vec::new() }
-}
-
-fn get_unsize_trait(db: &dyn HirDatabase, krate: CrateId) -> Option<TraitId> {
- let target = db.lang_item(krate, "unsize".into())?;
- match target {
- LangItemTarget::TraitId(t) => Some(t),
- _ => None,
- }
-}
projects / rust.git / commitdiff