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[ty] Use first matching constructor overload when inferring specializations #18204

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Merged
dcreager merged 2 commits into from
May 19, 2025
Merged

[ty] Use first matching constructor overload when inferring specializations #18204

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93be323
add tests
dcreager May 19, 2025
b6750d9
Only use first matching constructor
dcreager May 19, 2025
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6 changes: 6 additions & 0 deletions crates/ty_python_semantic/resources/mdtest/generics/legacy/classes.md
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Original file line number Diff line number Diff line change
Expand Up @@ -354,6 +354,8 @@ class C(Generic[T]):
@overload
def __init__(self: "C[bytes]", x: bytes) -> None: ...
@overload
def __init__(self: "C[int]", x: bytes) -> None: ...
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@carljm carljm May 19, 2025

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Maybe not worth a separate follow-up PR, but wouldn't we ideally have a case where the second argument is optional and so we can have multiple matching overloads, and show that we pick the first?

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@dcreager dcreager May 19, 2025

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This gives us two matching overloads if you provide a bytes parameter, and we show that we pick the first (giving C[bytes] instead of C[int] or C[bytes | int]). Maybe deserves a comment, since the argument / specialization pattern across the overloads is subtle?

@overload
def __init__(self, x: int) -> None: ...
def __init__(self, x: str | bytes | int) -> None: ...

Expand All @@ -369,6 +371,10 @@ C[bytes]("string") # error: [no-matching-overload]
C[bytes](b"bytes")
C[bytes](12)

C[int]("string") # error: [no-matching-overload]
C[int](b"bytes")
C[int](12)

C[None]("string") # error: [no-matching-overload]
C[None](b"bytes") # error: [no-matching-overload]
C[None](12)
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6 changes: 6 additions & 0 deletions crates/ty_python_semantic/resources/mdtest/generics/pep695/classes.md
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Expand Up @@ -290,6 +290,8 @@ class C[T]:
@overload
def __init__(self: C[bytes], x: bytes) -> None: ...
@overload
def __init__(self: C[int], x: bytes) -> None: ...
@overload
def __init__(self, x: int) -> None: ...
def __init__(self, x: str | bytes | int) -> None: ...

Expand All @@ -305,6 +307,10 @@ C[bytes]("string") # error: [no-matching-overload]
C[bytes](b"bytes")
C[bytes](12)

C[int]("string") # error: [no-matching-overload]
C[int](b"bytes")
C[int](12)

C[None]("string") # error: [no-matching-overload]
C[None](b"bytes") # error: [no-matching-overload]
C[None](12)
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23 changes: 8 additions & 15 deletions crates/ty_python_semantic/src/types.rs
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Expand Up @@ -4649,32 +4649,25 @@ impl<'db> Type<'db> {
}
}

fn combine_binding_specialization<'db>(
db: &'db dyn Db,
binding: &CallableBinding<'db>,
) -> Option<Specialization<'db>> {
binding
.matching_overloads()
.map(|(_, binding)| binding.inherited_specialization())
.reduce(|acc, specialization| {
combine_specializations(db, acc, specialization)
})
.flatten()
}

let new_specialization = new_call_outcome
.and_then(Result::ok)
.as_ref()
.and_then(Bindings::single_element)
.and_then(|binding| combine_binding_specialization(db, binding))
.into_iter()
.flat_map(CallableBinding::matching_overloads)
.next()
.and_then(|(_, binding)| binding.inherited_specialization())
Comment on lines -4669 to +4659
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@dhruvmanila dhruvmanila May 19, 2025 •
edited
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I think this is my mistake as I didn't revert this part from #17618 and only reverted the intersection of return type, sorry! 🙈

.filter(|specialization| {
Some(specialization.generic_context(db)) == generic_context
});
let init_specialization = init_call_outcome
.and_then(Result::ok)
.as_ref()
.and_then(Bindings::single_element)
.and_then(|binding| combine_binding_specialization(db, binding))
.into_iter()
.flat_map(CallableBinding::matching_overloads)
.next()
.and_then(|(_, binding)| binding.inherited_specialization())
.filter(|specialization| {
Some(specialization.generic_context(db)) == generic_context
});
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