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feat: Support #[feature(associated_type_defaults)] #21243

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Merged
ShoyuVanilla merged 1 commit into from
Dec 11, 2025
Merged

feat: Support #[feature(associated_type_defaults)] #21243

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9 changes: 1 addition & 8 deletions crates/hir-ty/src/next_solver/interner.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1104,14 +1104,7 @@ impl<'db> Interner for DbInterner<'db> {

fn type_of(self, def_id: Self::DefId) -> EarlyBinder<Self, Self::Ty> {
match def_id {
SolverDefId::TypeAliasId(id) => {
use hir_def::Lookup;
match id.lookup(self.db()).container {
ItemContainerId::ImplId(it) => it,
_ => panic!("assoc ty value should be in impl"),
};
self.db().ty(id.into())
}
SolverDefId::TypeAliasId(id) => self.db().ty(id.into()),
SolverDefId::AdtId(id) => self.db().ty(id.into()),
// FIXME(next-solver): This uses the types of `query mir_borrowck` in rustc.
//
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85 changes: 46 additions & 39 deletions crates/hir-ty/src/next_solver/solver.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -177,45 +177,52 @@ impl<'db> SolverDelegate for SolverContext<'db> {
impl_id: ImplIdWrapper,
) -> Result<Option<SolverDefId>, ErrorGuaranteed> {
let impl_items = impl_id.0.impl_items(self.0.interner.db());
let id = match trait_assoc_def_id {
SolverDefId::TypeAliasId(trait_assoc_id) => {
let trait_assoc_data = self.0.interner.db.type_alias_signature(trait_assoc_id);
impl_items
.items
.iter()
.find_map(|(impl_assoc_name, impl_assoc_id)| {
if let AssocItemId::TypeAliasId(impl_assoc_id) = *impl_assoc_id
&& *impl_assoc_name == trait_assoc_data.name
{
Some(impl_assoc_id)
} else {
None
}
})
.map(SolverDefId::TypeAliasId)
}
SolverDefId::ConstId(trait_assoc_id) => {
let trait_assoc_data = self.0.interner.db.const_signature(trait_assoc_id);
let trait_assoc_name = trait_assoc_data
.name
.as_ref()
.expect("unnamed consts should not get passed to the solver");
impl_items
.items
.iter()
.find_map(|(impl_assoc_name, impl_assoc_id)| {
if let AssocItemId::ConstId(impl_assoc_id) = *impl_assoc_id
&& impl_assoc_name == trait_assoc_name
{
Some(impl_assoc_id)
} else {
None
}
})
.map(SolverDefId::ConstId)
}
_ => panic!("Unexpected SolverDefId"),
};
let id =
match trait_assoc_def_id {
SolverDefId::TypeAliasId(trait_assoc_id) => {
let trait_assoc_data = self.0.interner.db.type_alias_signature(trait_assoc_id);
impl_items
.items
.iter()
.find_map(|(impl_assoc_name, impl_assoc_id)| {
if let AssocItemId::TypeAliasId(impl_assoc_id) = *impl_assoc_id
&& *impl_assoc_name == trait_assoc_data.name
{
Some(impl_assoc_id)
} else {
None
}
})
.or_else(|| {
if trait_assoc_data.ty.is_some() { Some(trait_assoc_id) } else { None }
})
.map(SolverDefId::TypeAliasId)
}
SolverDefId::ConstId(trait_assoc_id) => {
let trait_assoc_data = self.0.interner.db.const_signature(trait_assoc_id);
let trait_assoc_name = trait_assoc_data
.name
.as_ref()
.expect("unnamed consts should not get passed to the solver");
impl_items
.items
.iter()
.find_map(|(impl_assoc_name, impl_assoc_id)| {
if let AssocItemId::ConstId(impl_assoc_id) = *impl_assoc_id
&& impl_assoc_name == trait_assoc_name
{
Some(impl_assoc_id)
} else {
None
}
})
.or_else(|| {
if trait_assoc_data.has_body() { Some(trait_assoc_id) } else { None }
})
.map(SolverDefId::ConstId)
}
_ => panic!("Unexpected SolverDefId"),
};
Ok(id)
}

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20 changes: 20 additions & 0 deletions crates/hir-ty/src/tests/traits.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5079,3 +5079,23 @@ fn foo(base_layer_two: &dyn BaseLayerOne) {
"#,
);
}

#[test]
fn default_assoc_types() {
check_types(
r#"
trait Trait<T> {
type Assoc<U> = (T, U);
fn method(self) -> Self::Assoc<i32> { loop {} }
}

struct Struct<T>(T);
impl<T> Trait<((), T)> for Struct<T> {}

fn foo(v: Struct<f32>) {
v.method();
// ^^^^^^^^^^ (((), f32), i32)
}
"#,
);
}