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Fix associate type candidate collection #1115

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Merged
merged 1 commit into from
Aug 29, 2025
Merged

Fix associate type candidate collection #1115

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16 changes: 5 additions & 11 deletions crates/hir-analysis/src/name_resolution/path_resolver.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -746,10 +746,6 @@ pub fn find_associated_type<'db>(
};
}

// Collect unique candidates keyed by their normalized associated type.
// This avoids scanning and dedups different trait bounds that resolve to
// the same concrete type.
let mut candidates: IndexMap<TyId<'db>, TraitInstId<'db>> = IndexMap::new();
let ingot = scope.ingot(db);
// Use a single unification table and snapshots to preserve outer
// substitutions while isolating per-candidate attempts.
Expand Down Expand Up @@ -784,6 +780,7 @@ pub fn find_associated_type<'db>(
}
}

let mut candidates = SmallVec::new();
// Check explicit bounds in assumptions that match `ty` only when `ty` is a type
// parameter (to avoid spurious ambiguities for concrete types that already have impls).
if let TyData::TyParam(_) = ty.value.data(db) {
Expand All @@ -796,7 +793,7 @@ pub fn find_associated_type<'db>(
if table.unify(lhs_ty, pred_self_ty).is_ok() {
if let Some(assoc_ty) = trait_inst.assoc_ty(db, name) {
let folded = assoc_ty.fold_with(&mut table);
candidates.entry(folded).or_insert(trait_inst);
candidates.push((trait_inst, folded));
}
}
table.rollback_to(snapshot);
Expand All @@ -811,7 +808,7 @@ pub fn find_associated_type<'db>(
if table.unify(lhs_ty, impl_.self_ty(db)).is_ok() {
if let Some(ty) = impl_.assoc_ty(db, name) {
let folded = ty.fold_with(&mut table);
candidates.entry(folded).or_insert(impl_.trait_(db));
candidates.push((impl_.trait_(db), folded));
}
}
table.rollback_to(snapshot);
Expand All @@ -832,7 +829,7 @@ pub fn find_associated_type<'db>(
if table.unify(ty_with_subst, trait_inst.self_ty(db)).is_ok() {
if let Some(assoc_ty) = trait_inst.assoc_ty(db, name) {
let folded = assoc_ty.fold_with(&mut table);
candidates.entry(folded).or_insert(trait_inst);
candidates.push((trait_inst, folded));
}
}
table.rollback_to(snapshot);
Expand All @@ -852,17 +849,14 @@ pub fn find_associated_type<'db>(
if let Ok(inst) = lower_trait_ref(db, self_ty, *trait_ref, scope, assumptions) {
if let Some(assoc_ty) = inst.assoc_ty(db, name) {
let folded = assoc_ty.fold_with(&mut table);
candidates.entry(folded).or_insert(inst);
candidates.push((inst, folded));
}
}
}
}
}

candidates
.into_iter()
.map(|(ty, inst)| (inst, ty))
.collect()
}

pub fn resolve_name_res<'db>(
Expand Down
21 changes: 18 additions & 3 deletions crates/hir-analysis/test_files/ty_check/default_generic_trait.fe
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Original file line number Diff line number Diff line change
Expand Up @@ -3,12 +3,27 @@ trait Add<T = Self> {

fn add(self: Self, _ rhs: T) -> Self::Output
}
trait Sub<T = Self> {
type Output = Self

fn sub(self: Self, _ rhs: T) -> Self::Output
}

struct Foo {}
struct Bar {}

impl Add for i32 {
impl Add for Foo {
fn add(self: Self, _ rhs: Self) -> Self { self }
}
impl Sub for Foo {
fn sub(self: Self, _ rhs: Self) -> Self { self }
}
impl Add for Bar {
fn add(self: Self, _ rhs: Self) -> Self { self }
}

fn f(x: i32) -> i32 {
fn f(x: Foo, y: Bar) -> Foo {
y.add(y)
x.sub(x)
x.add(x)
}

107 changes: 84 additions & 23 deletions crates/hir-analysis/test_files/ty_check/default_generic_trait.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -4,41 +4,102 @@ expression: res
input_file: test_files/ty_check/default_generic_trait.fe
---
note:
┌─ default_generic_trait.fe:8:45
│
8 │ fn add(self: Self, _ rhs: Self) -> Self { self }
│ ^^^^^^^^ i32
┌─ default_generic_trait.fe:16:45
│
16 │ fn add(self: Self, _ rhs: Self) -> Self { self }
│ ^^^^^^^^ Foo

note:
┌─ default_generic_trait.fe:16:47
│
16 │ fn add(self: Self, _ rhs: Self) -> Self { self }
│ ^^^^ Foo

note:
┌─ default_generic_trait.fe:19:45
│
19 │ fn sub(self: Self, _ rhs: Self) -> Self { self }
│ ^^^^^^^^ Foo

note:
┌─ default_generic_trait.fe:19:47
│
19 │ fn sub(self: Self, _ rhs: Self) -> Self { self }
│ ^^^^ Foo

note:
┌─ default_generic_trait.fe:22:45
│
22 │ fn add(self: Self, _ rhs: Self) -> Self { self }
│ ^^^^^^^^ Bar

note:
┌─ default_generic_trait.fe:8:47
│
8 │ fn add(self: Self, _ rhs: Self) -> Self { self }
│ ^^^^ i32
┌─ default_generic_trait.fe:22:47
│
22 │ fn add(self: Self, _ rhs: Self) -> Self { self }
│ ^^^^ Bar

note:
┌─ default_generic_trait.fe:11:21
┌─ default_generic_trait.fe:25:29
│
11 │ fn f(x: i32) -> i32 {
│ ╭─────────────────────^
12 │ │ x.add(x)
13 │ │ }
│ ╰─^ i32
25 │ fn f(x: Foo, y: Bar) -> Foo {
│ ╭─────────────────────────────^
26 │ │ y.add(y)
27 │ │ x.sub(x)
28 │ │ x.add(x)
29 │ │ }
│ ╰─^ Foo

note:
┌─ default_generic_trait.fe:12:5
┌─ default_generic_trait.fe:26:5
│
12 │ x.add(x)
│ ^ i32
26 │ y.add(y)
│ ^ Bar

note:
┌─ default_generic_trait.fe:12:5
┌─ default_generic_trait.fe:26:5
│
12 │ x.add(x)
│ ^^^^^^^^ i32
26 │ y.add(y)
│ ^^^^^^^^ Bar

note:
┌─ default_generic_trait.fe:12:11
┌─ default_generic_trait.fe:26:11
│
12 │ x.add(x)
│ ^ i32
26 │ y.add(y)
│ ^ Bar

note:
┌─ default_generic_trait.fe:27:5
│
27 │ x.sub(x)
│ ^ Foo

note:
┌─ default_generic_trait.fe:27:5
│
27 │ x.sub(x)
│ ^^^^^^^^ Foo

note:
┌─ default_generic_trait.fe:27:11
│
27 │ x.sub(x)
│ ^ Foo

note:
┌─ default_generic_trait.fe:28:5
│
28 │ x.add(x)
│ ^ Foo

note:
┌─ default_generic_trait.fe:28:5
│
28 │ x.add(x)
│ ^^^^^^^^ Foo

note:
┌─ default_generic_trait.fe:28:11
│
28 │ x.add(x)
│ ^ Foo
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