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[ty] Remove false positives when subscripting Generic or Protocol with a ParamSpec or TypeVarTuple (#19749)

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Alex Waygood 2025-08-04 21:42:46 +01:00 • committed by GitHub
parent 739c94f95a
commit 3a9341f7be
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2 changed files with 37 additions and 14 deletions
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7
crates/ty_python_semantic/resources/mdtest/type_properties/is_assignable_to.md
View file

@ -1052,8 +1052,7 @@ class FooLegacy(Generic[T]):
class Bar[T, **P]:
def __call__(self): ...
# TODO: should not error
class BarLegacy(Generic[T, P]): # error: [invalid-argument-type] "`ParamSpec` is not a valid argument to `Generic`"
class BarLegacy(Generic[T, P]):
def __call__(self): ...
static_assert(is_assignable_to(Foo, Callable[..., Any]))
@ -1064,9 +1063,7 @@ static_assert(is_assignable_to(BarLegacy, Callable[..., Any]))
class Spam[T]: ...
class SpamLegacy(Generic[T]): ...
class Eggs[T, **P]: ...
# TODO: should not error
class EggsLegacy(Generic[T, P]): ... # error: [invalid-argument-type] "`ParamSpec` is not a valid argument to `Generic`"
class EggsLegacy(Generic[T, P]): ...
static_assert(not is_assignable_to(Spam, Callable[..., Any]))
static_assert(not is_assignable_to(SpamLegacy, Callable[..., Any]))

44
crates/ty_python_semantic/src/types/infer.rs
View file

@ -8563,7 +8563,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
fn infer_subscript_expression_types(
&self,
value_node: &ast::Expr,
value_node: &'ast ast::Expr,
value_ty: Type<'db>,
slice_ty: Type<'db>,
expr_context: ExprContext,
@ -8732,7 +8732,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
.map(|context| {
Type::KnownInstance(KnownInstanceType::SubscriptedProtocol(context))
})
.unwrap_or_else(Type::unknown),
.unwrap_or_else(GenericContextError::into_type),
// TODO: emit a diagnostic
TupleSpec::Variable(_) => Type::unknown(),
})
@ -8745,7 +8745,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
LegacyGenericBase::Protocol,
)
.map(|context| Type::KnownInstance(KnownInstanceType::SubscriptedProtocol(context)))
.unwrap_or_else(Type::unknown),
.unwrap_or_else(GenericContextError::into_type),
),
(Type::KnownInstance(KnownInstanceType::SubscriptedProtocol(_)), _) => {
@ -8764,7 +8764,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
.map(|context| {
Type::KnownInstance(KnownInstanceType::SubscriptedGeneric(context))
})
.unwrap_or_else(Type::unknown),
.unwrap_or_else(GenericContextError::into_type),
// TODO: emit a diagnostic
TupleSpec::Variable(_) => Type::unknown(),
})
@ -8777,7 +8777,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
LegacyGenericBase::Generic,
)
.map(|context| Type::KnownInstance(KnownInstanceType::SubscriptedGeneric(context)))
.unwrap_or_else(Type::unknown),
.unwrap_or_else(GenericContextError::into_type),
),
(Type::KnownInstance(KnownInstanceType::SubscriptedGeneric(_)), _) => {
@ -8946,11 +8946,19 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
value_node: &ast::Expr,
typevars: &[Type<'db>],
origin: LegacyGenericBase,
) -> Option<GenericContext<'db>> {
let typevars: Option<FxOrderSet<_>> = typevars
) -> Result<GenericContext<'db>, GenericContextError> {
let typevars: Result<FxOrderSet<_>, GenericContextError> = typevars
.iter()
.map(|typevar| match typevar {
Type::KnownInstance(KnownInstanceType::TypeVar(typevar)) => Some(*typevar),
Type::KnownInstance(KnownInstanceType::TypeVar(typevar)) => Ok(*typevar),
Type::NominalInstance(NominalInstanceType { class, .. })
if matches!(
class.known(self.db()),
Some(KnownClass::TypeVarTuple | KnownClass::ParamSpec)
) =>
{
Err(GenericContextError::NotYetSupported)
}
_ => {
if let Some(builder) =
self.context.report_lint(&INVALID_ARGUMENT_TYPE, value_node)
@ -8960,7 +8968,7 @@ impl<'db, 'ast> TypeInferenceBuilder<'db, 'ast> {
typevar.display(self.db()),
));
}
None
Err(GenericContextError::InvalidArgument)
}
})
.collect();
@ -10860,6 +10868,24 @@ impl<'db> TypeInferenceBuilder<'db, '_> {
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum GenericContextError {
/// It's invalid to subscript `Generic` or `Protocol` with this type
InvalidArgument,
/// It's valid to subscribe `Generic` or `Protocol` with this type,
/// but the type is not yet supported.
NotYetSupported,
}
impl GenericContextError {
const fn into_type<'db>(self) -> Type<'db> {
match self {
GenericContextError::InvalidArgument => Type::unknown(),
GenericContextError::NotYetSupported => todo_type!("ParamSpecs and TypeVarTuples"),
}
}
}
/// The deferred state of a specific expression in an inference region.
#[derive(Default, Debug, Clone, Copy)]
enum DeferredExpressionState {