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Remove built-in Unsize impls

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They exist in Chalk now.
This commit is contained in:
Florian Diebold
2020-07-11 16:29:09 +02:00
parent 71d645101d
commit 2a4166501d
4 changed files with 6 additions and 235 deletions
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7
crates/ra_hir_ty/src/traits.rs
View File

@@ -295,13 +295,8 @@ pub enum Impl {
/// A normal impl from an impl block.
ImplDef(ImplId),
/// Closure types implement the Fn traits synthetically.
// FIXME: implement closure support from Chalk, remove this
ClosureFnTraitImpl(ClosureFnTraitImplData),
/// [T; n]: Unsize<[T]>
UnsizeArray,
/// T: Unsize<dyn Trait> where T: Trait
UnsizeToTraitObject(TraitId),
/// dyn Trait: Unsize<dyn SuperTrait> if Trait: SuperTrait
UnsizeToSuperTraitObject(UnsizeToSuperTraitObjectData),
}
/// This exists just for Chalk, because our ImplIds are only unique per module.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]

201
crates/ra_hir_ty/src/traits/builtin.rs
View File

@@ -1,15 +1,12 @@
//! 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 {
@@ -31,7 +28,7 @@ pub(super) fn get_builtin_impls(
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),
) {
@@ -50,60 +47,12 @@ pub(super) fn get_builtin_impls(
}
}
}
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)
}
}
}
@@ -227,145 +176,3 @@ fn closure_fn_trait_output_assoc_ty_value(
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(&current_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,
}
}

1
crates/ra_hir_ty/src/traits/chalk/mapping.rs
View File

@@ -271,6 +271,7 @@ impl ToChalk for TypeCtor {
}
TypeCtor::Never => TypeName::Never,
// FIXME convert these
TypeCtor::Adt(_)
| TypeCtor::Array
| TypeCtor::FnPtr { .. }

32
crates/ra_hir_ty/src/utils.rs
View File

@@ -110,38 +110,6 @@ pub(super) fn all_super_trait_refs(db: &dyn HirDatabase, trait_ref: TraitRef) ->
result
}
/// Finds a path from a trait to one of its super traits. Returns an empty
/// vector if there is no path.
pub(super) fn find_super_trait_path(
db: &dyn DefDatabase,
trait_: TraitId,
super_trait: TraitId,
) -> Vec<TraitId> {
let mut result = Vec::with_capacity(2);
result.push(trait_);
return if go(db, super_trait, &mut result) { result } else { Vec::new() };
fn go(db: &dyn DefDatabase, super_trait: TraitId, path: &mut Vec<TraitId>) -> bool {
let trait_ = *path.last().unwrap();
if trait_ == super_trait {
return true;
}
for tt in direct_super_traits(db, trait_) {
if path.contains(&tt) {
continue;
}
path.push(tt);
if go(db, super_trait, path) {
return true;
} else {
path.pop();
}
}
false
}
}
pub(super) fn associated_type_by_name_including_super_traits(
db: &dyn HirDatabase,
trait_ref: TraitRef,