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fix: Fix implicit ty args being lowered where they shouldn't #17175

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merged 1 commit into from
May 2, 2024
Merged

fix: Fix implicit ty args being lowered where they shouldn't #17175

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2 changes: 1 addition & 1 deletion crates/hir-def/src/generics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -377,7 +377,7 @@ impl GenericParamsCollector {
}
}

pub(crate) fn fill_implicit_impl_trait_args(
fn fill_implicit_impl_trait_args(
&mut self,
db: &dyn DefDatabase,
exp: &mut Lazy<(Arc<DefMap>, Expander), impl FnOnce() -> (Arc<DefMap>, Expander)>,
Expand Down
2 changes: 1 addition & 1 deletion crates/hir-def/src/item_tree/lower.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -662,7 +662,7 @@ impl<'a> Ctx<'a> {
let attrs = RawAttrs::new(self.db.upcast(), &param, self.body_ctx.span_map());
debug_assert!(self.generic_param_attr_buffer.insert(item, attrs).is_none());
};

self.body_ctx.take_impl_traits_bounds();
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Issue was basically this line missing. Without it, we start allocating impl trait args for things that are not related to the generic params / where clauses

let mut generics = GenericParamsCollector::default();

if let HasImplicitSelf::Yes(bounds) = has_implicit_self {
Expand Down
211 changes: 93 additions & 118 deletions crates/hir-ty/src/lower.rs
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Expand Up @@ -345,51 +345,43 @@ impl<'a> TyLoweringContext<'a> {
}
ImplTraitLoweringState::Param(counter) => {
let idx = counter.get();
// FIXME we're probably doing something wrong here
counter.set(idx + count_impl_traits(type_ref) as u16);
if let Some(generics) = self.generics() {
let param = generics
.iter()
.filter(|(_, data)| {
matches!(
data,
GenericParamDataRef::TypeParamData(data)
if data.provenance == TypeParamProvenance::ArgumentImplTrait
)
})
.nth(idx as usize)
.map_or(TyKind::Error, |(id, _)| {
if let GenericParamId::TypeParamId(id) = id {
TyKind::Placeholder(to_placeholder_idx(self.db, id.into()))
} else {
// we just filtered them out
unreachable!("Unexpected lifetime or const argument");
}
});
param.intern(Interner)
} else {
TyKind::Error.intern(Interner)
}
counter.set(idx + 1);
let kind = self
.generics()
.expect("param impl trait lowering must be in a generic def")
.iter()
.filter_map(|(id, data)| match (id, data) {
(
GenericParamId::TypeParamId(id),
GenericParamDataRef::TypeParamData(data),
) if data.provenance == TypeParamProvenance::ArgumentImplTrait => {
Some(id)
}
_ => None,
})
.nth(idx as usize)
.map_or(TyKind::Error, |id| {
TyKind::Placeholder(to_placeholder_idx(self.db, id.into()))
});
kind.intern(Interner)
}
ImplTraitLoweringState::Variable(counter) => {
let idx = counter.get();
// FIXME we're probably doing something wrong here
counter.set(idx + count_impl_traits(type_ref) as u16);
counter.set(idx + 1);
let (
_parent_params,
self_params,
list_params,
type_params,
const_params,
_impl_trait_params,
_lifetime_params,
) = if let Some(generics) = self.generics() {
generics.provenance_split()
} else {
(0, 0, 0, 0, 0, 0)
};
) = self
.generics()
.expect("variable impl trait lowering must be in a generic def")
.provenance_split();
TyKind::BoundVar(BoundVar::new(
self.in_binders,
idx as usize + self_params + list_params + const_params,
idx as usize + self_params + type_params + const_params,
))
.intern(Interner)
}
Expand Down Expand Up @@ -1150,84 +1142,77 @@ impl<'a> TyLoweringContext<'a> {
binding.type_ref.as_ref().map_or(0, |_| 1) + binding.bounds.len(),
);
if let Some(type_ref) = &binding.type_ref {
if let (
TypeRef::ImplTrait(bounds),
ImplTraitLoweringState::Param(_)
| ImplTraitLoweringState::Variable(_)
| ImplTraitLoweringState::Disallowed,
) = (type_ref, &self.impl_trait_mode)
{
for bound in bounds {
predicates.extend(
self.lower_type_bound(
bound,
TyKind::Alias(AliasTy::Projection(projection_ty.clone()))
.intern(Interner),
false,
),
);
match (type_ref, &self.impl_trait_mode) {
(TypeRef::ImplTrait(_), ImplTraitLoweringState::Disallowed) => (),
(
_,
ImplTraitLoweringState::Disallowed | ImplTraitLoweringState::Opaque(_),
) => {
let ty = self.lower_ty(type_ref);
let alias_eq =
AliasEq { alias: AliasTy::Projection(projection_ty.clone()), ty };
predicates
.push(crate::wrap_empty_binders(WhereClause::AliasEq(alias_eq)));
}
} else {
let ty = 'ty: {
if matches!(
self.impl_trait_mode,
ImplTraitLoweringState::Param(_)
| ImplTraitLoweringState::Variable(_)
) {
// Find the generic index for the target of our `bound`
let target_param_idx = self
.resolver
.where_predicates_in_scope()
.find_map(|(p, _)| match p {
WherePredicate::TypeBound {
target: WherePredicateTypeTarget::TypeOrConstParam(idx),
bound: b,
} if b == bound => Some(idx),
_ => None,
});
if let Some(target_param_idx) = target_param_idx {
let mut counter = 0;
let generics = self.generics().expect("generics in scope");
for (idx, data) in generics.params.type_or_consts.iter() {
// Count the number of `impl Trait` things that appear before
// the target of our `bound`.
// Our counter within `impl_trait_mode` should be that number
// to properly lower each types within `type_ref`
if data.type_param().is_some_and(|p| {
p.provenance == TypeParamProvenance::ArgumentImplTrait
}) {
counter += 1;
}
if idx == *target_param_idx {
break;
}
(
_,
ImplTraitLoweringState::Param(_) | ImplTraitLoweringState::Variable(_),
) => {
// Find the generic index for the target of our `bound`
let target_param_idx = self
.resolver
.where_predicates_in_scope()
.find_map(|(p, _)| match p {
WherePredicate::TypeBound {
target: WherePredicateTypeTarget::TypeOrConstParam(idx),
bound: b,
} if b == bound => Some(idx),
_ => None,
});
let ty = if let Some(target_param_idx) = target_param_idx {
let mut counter = 0;
let generics = self.generics().expect("generics in scope");
for (idx, data) in generics.params.type_or_consts.iter() {
// Count the number of `impl Trait` things that appear before
// the target of our `bound`.
// Our counter within `impl_trait_mode` should be that number
// to properly lower each types within `type_ref`
if data.type_param().is_some_and(|p| {
p.provenance == TypeParamProvenance::ArgumentImplTrait
}) {
counter += 1;
}
let mut ext = TyLoweringContext::new_maybe_unowned(
self.db,
self.resolver,
self.owner,
)
.with_type_param_mode(self.type_param_mode);
match &self.impl_trait_mode {
ImplTraitLoweringState::Param(_) => {
ext.impl_trait_mode =
ImplTraitLoweringState::Param(Cell::new(counter));
}
ImplTraitLoweringState::Variable(_) => {
ext.impl_trait_mode = ImplTraitLoweringState::Variable(
Cell::new(counter),
);
}
_ => unreachable!(),
if idx == *target_param_idx {
break;
}
break 'ty ext.lower_ty(type_ref);
}
}
self.lower_ty(type_ref)
};
let alias_eq =
AliasEq { alias: AliasTy::Projection(projection_ty.clone()), ty };
predicates.push(crate::wrap_empty_binders(WhereClause::AliasEq(alias_eq)));
let mut ext = TyLoweringContext::new_maybe_unowned(
self.db,
self.resolver,
self.owner,
)
.with_type_param_mode(self.type_param_mode);
match &self.impl_trait_mode {
ImplTraitLoweringState::Param(_) => {
ext.impl_trait_mode =
ImplTraitLoweringState::Param(Cell::new(counter));
}
ImplTraitLoweringState::Variable(_) => {
ext.impl_trait_mode =
ImplTraitLoweringState::Variable(Cell::new(counter));
}
_ => unreachable!(),
}
ext.lower_ty(type_ref)
} else {
self.lower_ty(type_ref)
};

let alias_eq =
AliasEq { alias: AliasTy::Projection(projection_ty.clone()), ty };
predicates
.push(crate::wrap_empty_binders(WhereClause::AliasEq(alias_eq)));
}
}
}
for bound in binding.bounds.iter() {
Expand Down Expand Up @@ -1394,16 +1379,6 @@ impl<'a> TyLoweringContext<'a> {
}
}

fn count_impl_traits(type_ref: &TypeRef) -> usize {
let mut count = 0;
type_ref.walk(&mut |type_ref| {
if matches!(type_ref, TypeRef::ImplTrait(_)) {
count += 1;
}
});
count
}

/// Build the signature of a callable item (function, struct or enum variant).
pub(crate) fn callable_item_sig(db: &dyn HirDatabase, def: CallableDefId) -> PolyFnSig {
match def {
Expand Down
21 changes: 21 additions & 0 deletions crates/hir-ty/src/tests/regression.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1975,3 +1975,24 @@ impl<#[cfg(feature = "a-feature")] A> Bar for (){}
"#,
)
}

#[test]
fn nested_anon_generics_and_where_bounds_17173() {
check_types(
r#"
//- minicore: sized
pub trait Lookup {
type Data;
fn lookup(&self) -> Self::Data;
}
pub trait ItemTreeLoc {
type Id;
}
fn id_to_generics(id: impl Lookup<Data = impl ItemTreeLoc<Id = ()>>)
//^^ impl Lookup<Data = impl ItemTreeLoc<Id = ()>>
where
(): Sized,
{}
"#,
);
}