wip: subscript always via __getitem__

crates/red_knot_python_semantic/src/types.rs

@@ -659,6 +659,7 @@ impl<'db> Type<'db> {
                     .to_instance(db)
                     .is_subtype_of(db, target)
             }
+            (Type::Callable(CallableType::SpecializedGetitem), _) => self == target,
 
             (
                 Type::Callable(CallableType::General(self_callable)),
@@ -1053,7 +1054,8 @@ impl<'db> Type<'db> {
                 | Type::Callable(
                     CallableType::BoundMethod(..)
                     | CallableType::MethodWrapperDunderGet(..)
-                    | CallableType::WrapperDescriptorDunderGet,
+                    | CallableType::WrapperDescriptorDunderGet
+                    | CallableType::SpecializedGetitem,
                 )
                 | Type::ModuleLiteral(..)
                 | Type::ClassLiteral(..)
@@ -1067,7 +1069,8 @@ impl<'db> Type<'db> {
                 | Type::Callable(
                     CallableType::BoundMethod(..)
                     | CallableType::MethodWrapperDunderGet(..)
-                    | CallableType::WrapperDescriptorDunderGet,
+                    | CallableType::WrapperDescriptorDunderGet
+                    | CallableType::SpecializedGetitem,
                 )
                 | Type::ModuleLiteral(..)
                 | Type::ClassLiteral(..)
@@ -1267,6 +1270,9 @@ impl<'db> Type<'db> {
                 Type::Callable(CallableType::WrapperDescriptorDunderGet),
             ) => !KnownClass::WrapperDescriptorType.is_subclass_of(db, class),
 
+            (Type::Callable(CallableType::SpecializedGetitem), Type::Instance(_))
+            | (Type::Instance(_), Type::Callable(CallableType::SpecializedGetitem)) => true,
+
             (Type::ModuleLiteral(..), other @ Type::Instance(..))
             | (other @ Type::Instance(..), Type::ModuleLiteral(..)) => {
                 // Modules *can* actually be instances of `ModuleType` subclasses
@@ -1321,7 +1327,8 @@ impl<'db> Type<'db> {
             | Type::Callable(
                 CallableType::BoundMethod(_)
                 | CallableType::MethodWrapperDunderGet(_)
-                | CallableType::WrapperDescriptorDunderGet,
+                | CallableType::WrapperDescriptorDunderGet
+                | CallableType::SpecializedGetitem,
             )
             | Type::ModuleLiteral(..)
             | Type::IntLiteral(_)
@@ -1391,7 +1398,8 @@ impl<'db> Type<'db> {
             | Type::Callable(
                 CallableType::BoundMethod(_)
                 | CallableType::MethodWrapperDunderGet(_)
-                | CallableType::WrapperDescriptorDunderGet,
+                | CallableType::WrapperDescriptorDunderGet
+                | CallableType::SpecializedGetitem,
             )
             | Type::ClassLiteral(..)
             | Type::ModuleLiteral(..)
@@ -1440,7 +1448,8 @@ impl<'db> Type<'db> {
             | Type::Callable(
                 CallableType::BoundMethod(..)
                 | CallableType::MethodWrapperDunderGet(..)
-                | CallableType::WrapperDescriptorDunderGet,
+                | CallableType::WrapperDescriptorDunderGet
+                | CallableType::SpecializedGetitem,
             )
             | Type::ModuleLiteral(..)
             | Type::ClassLiteral(..)
@@ -1513,6 +1522,7 @@ impl<'db> Type<'db> {
                         // Hard code this knowledge, as we look up `__set__` and `__delete__` on `FunctionType` often.
                         Some(Symbol::Unbound.into())
                     }
+
                     // TODO:
                     // We currently hard-code the knowledge that the following known classes are not
                     // descriptors, i.e. that they have no `__get__` method. This is not wrong and
@@ -1652,7 +1662,8 @@ impl<'db> Type<'db> {
                     .to_instance(db)
                     .instance_member(db, name)
             }
-            Type::Callable(CallableType::General(_)) => {
+            Type::Callable(CallableType::SpecializedGetitem)
+            | Type::Callable(CallableType::General(_)) => {
                 KnownClass::Object.to_instance(db).instance_member(db, name)
             }
 
@@ -2006,21 +2017,31 @@ impl<'db> Type<'db> {
                     .to_instance(db)
                     .member(db, &name)
             }
-            Type::Callable(CallableType::General(_)) => {
+            Type::Callable(CallableType::SpecializedGetitem)
+            | Type::Callable(CallableType::General(_)) => {
                 KnownClass::Object.to_instance(db).member(db, &name)
             }
 
             Type::Instance(InstanceType { class })
-                if matches!(name.as_str(), "major" | "minor")
+                if matches!(name_str, "__getitem__" | "major" | "minor")
                     && class.is_known(db, KnownClass::VersionInfo) =>
             {
-                let python_version = Program::get(db).python_version(db);
-                let segment = if name == "major" {
-                    python_version.major
-                } else {
-                    python_version.minor
-                };
-                Symbol::bound(Type::IntLiteral(segment.into())).into()
+                match name_str {
+                    "__getitem__" => {
+                        Symbol::bound(Type::Callable(CallableType::SpecializedGetitem)).into()
+                    }
+                    "major" => {
+                        let python_version = Program::get(db).python_version(db);
+                        let segment = python_version.major;
+                        Symbol::bound(Type::IntLiteral(segment.into())).into()
+                    }
+                    "minor" => {
+                        let python_version = Program::get(db).python_version(db);
+                        let segment = python_version.minor;
+                        Symbol::bound(Type::IntLiteral(segment.into())).into()
+                    }
+                    _ => unreachable!(),
+                }
             }
 
             Type::IntLiteral(_) if matches!(name_str, "real" | "numerator") => {
@@ -2455,6 +2476,20 @@ impl<'db> Type<'db> {
                 Signatures::single(signature)
             }
 
+            Type::Callable(CallableType::SpecializedGetitem) => {
+                let signature = CallableSignature::from_overloads(
+                    self,
+                    [Signature::new(
+                        Parameters::new([Parameter::positional_only(Some(Name::new_static(
+                            "slice",
+                        )))
+                        .with_annotated_type(KnownClass::Int.to_instance(db))]),
+                        None,
+                    )],
+                );
+                Signatures::single(signature)
+            }
+
             Type::FunctionLiteral(function_type) => match function_type.known(db) {
                 Some(
                     KnownFunction::IsEquivalentTo
@@ -3170,7 +3205,8 @@ impl<'db> Type<'db> {
             Type::Callable(CallableType::WrapperDescriptorDunderGet) => {
                 KnownClass::WrapperDescriptorType.to_class_literal(db)
             }
-            Type::Callable(CallableType::General(_)) => KnownClass::Type.to_instance(db),
+            Type::Callable(CallableType::SpecializedGetitem)
+            | Type::Callable(CallableType::General(_)) => KnownClass::Type.to_instance(db),
             Type::ModuleLiteral(_) => KnownClass::ModuleType.to_class_literal(db),
             Type::Tuple(_) => KnownClass::Tuple.to_class_literal(db),
             Type::ClassLiteral(ClassLiteralType { class }) => class.metaclass(db),
@@ -4857,6 +4893,9 @@ pub enum CallableType<'db> {
     /// type. We currently add this as a separate variant because `FunctionType.__get__`
     /// is an overloaded method and we do not support `@overload` yet.
     WrapperDescriptorDunderGet,
+
+    /// Represents specialized `__getitem__` methods
+    SpecializedGetitem,
 }
 
 #[salsa::interned(debug)]

crates/red_knot_python_semantic/src/types/display.rs

@@ -110,6 +110,9 @@ impl Display for DisplayRepresentation<'_> {
             Type::Callable(CallableType::WrapperDescriptorDunderGet) => {
                 f.write_str("<wrapper-descriptor `__get__` of `function` objects>")
             }
+            Type::Callable(CallableType::SpecializedGetitem) => {
+                f.write_str("<specialized `__getitem__`>")
+            }
             Type::Union(union) => union.display(self.db).fmt(f),
             Type::Intersection(intersection) => intersection.display(self.db).fmt(f),
             Type::IntLiteral(n) => n.fmt(f),

crates/red_knot_python_semantic/src/types/infer.rs

@@ -5543,20 +5543,6 @@ impl<'db> TypeInferenceBuilder<'db> {
         slice_ty: Type<'db>,
     ) -> Type<'db> {
         match (value_ty, slice_ty) {
-            (
-                Type::Instance(instance),
-                Type::IntLiteral(_) | Type::BooleanLiteral(_) | Type::SliceLiteral(_),
-            ) if instance
-                .class()
-                .is_known(self.db(), KnownClass::VersionInfo) =>
-            {
-                self.infer_subscript_expression_types(
-                    value_node,
-                    Type::version_info_tuple(self.db()),
-                    slice_ty,
-                )
-            }
-
             // Ex) Given `("a", "b", "c", "d")[1]`, return `"b"`
             (Type::Tuple(tuple_ty), Type::IntLiteral(int)) if i32::try_from(int).is_ok() => {
                 let elements = tuple_ty.elements(self.db());
@@ -5698,6 +5684,7 @@ impl<'db> TypeInferenceBuilder<'db> {
                         return err.fallback_return_type(self.db());
                     }
                     Err(CallDunderError::CallError(_, bindings)) => {
+                        bindings.report_diagnostics(&self.context, value_node.into());
                         self.context.report_lint(
                             &CALL_NON_CALLABLE,
                             value_node,

crates/red_knot_python_semantic/src/types/type_ordering.rs

@@ -83,6 +83,13 @@ pub(super) fn union_or_intersection_elements_ordering<'db>(
         (Type::Callable(CallableType::WrapperDescriptorDunderGet), _) => Ordering::Less,
         (_, Type::Callable(CallableType::WrapperDescriptorDunderGet)) => Ordering::Greater,
 
+        (
+            Type::Callable(CallableType::SpecializedGetitem),
+            Type::Callable(CallableType::SpecializedGetitem),
+        ) => Ordering::Equal,
+        (Type::Callable(CallableType::SpecializedGetitem), _) => Ordering::Less,
+        (_, Type::Callable(CallableType::SpecializedGetitem)) => Ordering::Greater,
+
         (Type::Callable(CallableType::General(_)), Type::Callable(CallableType::General(_))) => {
             Ordering::Equal
         }