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Fix a bug with predicate lowering of associated items

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The essence of the bug is that bounds on `impl Trait` got lowered with incorrect bound vars, as if we were lowering the parent.
This commit is contained in:
Chayim Refael Friedman 2025-04-17 00:19:54 +03:00
parent ea273513ed
commit e1962d2e22
2 changed files with 32 additions and 5 deletions
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18
crates/hir-ty/src/lower.rs
View File

@ -464,10 +464,14 @@ impl<'a> TyLoweringContext<'a> {
self.lower_trait_ref_from_path(trait_ref.path, explicit_self_ty).map(|it| it.0)
}
/// When lowering predicates from parents (impl, traits) for children defs (fns, consts, types), `generics` should
/// contain the `Generics` for the **child**, while `predicate_owner` should contain the `GenericDefId` of the
/// **parent**. This is important so we generate the correct bound var/placeholder.
pub(crate) fn lower_where_predicate<'b>(
&'b mut self,
where_predicate: &'b WherePredicate,
generics: &'b Generics,
predicate_owner: GenericDefId,
ignore_bindings: bool,
) -> impl Iterator<Item = QuantifiedWhereClause> + use<'a, 'b> {
match where_predicate {
@ -477,7 +481,7 @@ impl<'a> TyLoweringContext<'a> {
WherePredicateTypeTarget::TypeRef(type_ref) => self.lower_ty(*type_ref),
&WherePredicateTypeTarget::TypeOrConstParam(local_id) => {
let param_id =
hir_def::TypeOrConstParamId { parent: generics.def(), local_id };
hir_def::TypeOrConstParamId { parent: predicate_owner, local_id };
match self.type_param_mode {
ParamLoweringMode::Placeholder => {
TyKind::Placeholder(to_placeholder_idx(self.db, param_id))
@ -887,7 +891,7 @@ pub(crate) fn generic_predicates_for_param_query(
if invalid_target {
// If this is filtered out without lowering, `?Sized` is not gathered into `ctx.unsized_types`
if let TypeBound::Path(_, TraitBoundModifier::Maybe) = bound {
ctx.lower_where_predicate(pred, generics, true).for_each(drop);
ctx.lower_where_predicate(pred, generics, generics.def(), true).for_each(drop);
}
return false;
}
@ -924,7 +928,7 @@ pub(crate) fn generic_predicates_for_param_query(
for pred in maybe_parent_generics.where_predicates() {
if predicate(pred, maybe_parent_generics, &mut ctx) {
predicates.extend(
ctx.lower_where_predicate(pred, maybe_parent_generics, true)
ctx.lower_where_predicate(pred, &generics, maybe_parent_generics.def(), true)
.map(|p| make_binders(db, &generics, p)),
);
}
@ -987,7 +991,9 @@ pub(crate) fn trait_environment_query(
{
ctx.store = maybe_parent_generics.store();
for pred in maybe_parent_generics.where_predicates() {
for pred in ctx.lower_where_predicate(pred, maybe_parent_generics, false) {
for pred in
ctx.lower_where_predicate(pred, &generics, maybe_parent_generics.def(), false)
{
if let WhereClause::Implemented(tr) = pred.skip_binders() {
traits_in_scope
.push((tr.self_type_parameter(Interner).clone(), tr.hir_trait_id()));
@ -1085,8 +1091,10 @@ where
ctx.store = maybe_parent_generics.store();
for pred in maybe_parent_generics.where_predicates() {
if filter(pred, maybe_parent_generics.def()) {
// We deliberately use `generics` and not `maybe_parent_generics` here. This is not a mistake!
// If we use the parent generics
predicates.extend(
ctx.lower_where_predicate(pred, maybe_parent_generics, false)
ctx.lower_where_predicate(pred, &generics, maybe_parent_generics.def(), false)
.map(|p| make_binders(db, &generics, p)),
);
}

19
crates/ide/src/inlay_hints.rs
View File

@ -1032,4 +1032,23 @@ fn bar() {
"#,
);
}
#[test]
fn regression_19610() {
check(
r#"
trait Trait {
type Assoc;
}
struct Foo<A>(A);
impl<A: Trait<Assoc = impl Trait>> Foo<A> {
fn foo<'a, 'b>(_: &'a [i32], _: &'b [i32]) {}
}
fn bar() {
Foo::foo(&[1], &[2]);
}
"#,
);
}
}