[ty] Fix the inferred MRO of functional namedtuple classes (#22722)

crates/ty_python_semantic/resources/mdtest/named_tuple.md

@@ -8,7 +8,7 @@ name, and not just by its numeric position within the tuple:
 ### Basics
 
 ```py
-from typing import NamedTuple
+from typing import NamedTuple, Sequence
 from ty_extensions import static_assert, is_subtype_of, is_assignable_to, reveal_mro
 
 class Person(NamedTuple):
@@ -30,6 +30,8 @@ reveal_mro(Person)
 
 static_assert(is_subtype_of(Person, tuple[int, str, int | None]))
 static_assert(is_subtype_of(Person, tuple[object, ...]))
+static_assert(is_subtype_of(Person, Sequence[int | str | None]))
+static_assert(is_subtype_of(Person, Sequence[object]))
 static_assert(not is_assignable_to(Person, tuple[int, str, int]))
 static_assert(not is_assignable_to(Person, tuple[int, str]))
 
@@ -166,7 +168,7 @@ reveal_type(container.items)  # revealed: list[int]
 reveal_type(container.mapping)  # revealed: dict[str, bool]
 
 # MRO includes the properly specialized tuple type.
-# revealed: (<class 'Url'>, <class 'tuple[str, int]'>, <class 'object'>)
+# revealed: (<class 'Url'>, <class 'tuple[str, int]'>, <class 'Sequence[str | int]'>, <class 'Reversible[str | int]'>, <class 'Collection[str | int]'>, <class 'Iterable[str | int]'>, <class 'Container[str | int]'>, typing.Protocol, typing.Generic, <class 'object'>)
 reveal_mro(Url)
 
 static_assert(is_subtype_of(Url, tuple[str, int]))
@@ -219,7 +221,8 @@ NT = NamedTuple("NT", fields)
 
 # Fields are unknown, so attribute access returns Any and MRO has Unknown tuple.
 reveal_type(NT)  # revealed: <class 'NT'>
-reveal_mro(NT)  # revealed: (<class 'NT'>, <class 'tuple[Unknown, ...]'>, <class 'object'>)
+# revealed: (<class 'NT'>, <class 'tuple[Unknown, ...]'>, <class 'Sequence[Unknown]'>, <class 'Reversible[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(NT)
 reveal_type(NT(1, "a").x)  # revealed: Any
 ```
 
@@ -237,7 +240,8 @@ NT = collections.namedtuple("NT", field_names)
 
 # Fields are unknown, so attribute access returns Any and MRO has Unknown tuple.
 reveal_type(NT)  # revealed: <class 'NT'>
-reveal_mro(NT)  # revealed: (<class 'NT'>, <class 'tuple[Unknown, ...]'>, <class 'object'>)
+# revealed: (<class 'NT'>, <class 'tuple[Unknown, ...]'>, <class 'Sequence[Unknown]'>, <class 'Reversible[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(NT)
 reveal_type(NT(1, 2).x)  # revealed: Any
 ```
 
@@ -254,7 +258,7 @@ class Url(NamedTuple("Url", [("host", str), ("path", str)])):
     pass
 
 reveal_type(Url)  # revealed: <class 'Url'>
-# revealed: (<class 'mdtest_snippet.Url @ src/mdtest_snippet.py:4:7'>, <class 'mdtest_snippet.Url @ src/mdtest_snippet.py:4:11'>, <class 'tuple[str, str]'>, <class 'object'>)
+# revealed: (<class 'mdtest_snippet.Url @ src/mdtest_snippet.py:4:7'>, <class 'mdtest_snippet.Url @ src/mdtest_snippet.py:4:11'>, <class 'tuple[str, str]'>, <class 'Sequence[str]'>, <class 'Reversible[str]'>, <class 'Collection[str]'>, <class 'Iterable[str]'>, <class 'Container[str]'>, typing.Protocol, typing.Generic, <class 'object'>)
 reveal_mro(Url)
 reveal_type(Url.__new__)  # revealed: [Self](cls: type[Self], host: str, path: str) -> Self
 
@@ -364,7 +368,7 @@ reveal_type(config)  # revealed: GroundTruth
 reveal_type(config.duration)  # revealed: Any
 
 # Namedtuples with unknown fields inherit from tuple[Unknown, ...] to avoid false positives.
-# revealed: (<class 'GroundTruth'>, <class 'tuple[Unknown, ...]'>, <class 'object'>)
+# revealed: (<class 'GroundTruth'>, <class 'tuple[Unknown, ...]'>, <class 'Sequence[Unknown]'>, <class 'Reversible[Unknown]'>, <class 'Collection[Unknown]'>, <class 'Iterable[Unknown]'>, <class 'Container[Unknown]'>, typing.Protocol, typing.Generic, <class 'object'>)
 reveal_mro(GroundTruth)
 
 # No index-out-of-bounds error since the tuple length is unknown.
@@ -383,33 +387,38 @@ from ty_extensions import reveal_mro
 # String field names (space-separated)
 Point1 = collections.namedtuple("Point", "x y")
 reveal_type(Point1)  # revealed: <class 'Point'>
-reveal_mro(Point1)  # revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'object'>)
+# revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Point1)
 
 # String field names with multiple spaces
 Point1a = collections.namedtuple("Point", "x       y")
 reveal_type(Point1a)  # revealed: <class 'Point'>
-reveal_mro(Point1a)  # revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'object'>)
+# revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Point1a)
 
 # String field names (comma-separated also works at runtime)
 Point2 = collections.namedtuple("Point", "x, y")
 reveal_type(Point2)  # revealed: <class 'Point'>
-reveal_mro(Point2)  # revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'object'>)
+# revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Point2)
 
 # List of strings
 Point3 = collections.namedtuple("Point", ["x", "y"])
 reveal_type(Point3)  # revealed: <class 'Point'>
-reveal_mro(Point3)  # revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'object'>)
+# revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Point3)
 
 # Tuple of strings
 Point4 = collections.namedtuple("Point", ("x", "y"))
 reveal_type(Point4)  # revealed: <class 'Point'>
-reveal_mro(Point4)  # revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'object'>)
-
+# revealed: (<class 'Point'>, <class 'tuple[Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Point4)
 # Invalid: integer is not a valid typename
 # error: [invalid-argument-type]
 Invalid = collections.namedtuple(123, ["x", "y"])
 reveal_type(Invalid)  # revealed: <class '<unknown>'>
-reveal_mro(Invalid)  # revealed: (<class '<unknown>'>, <class 'tuple[Any, Any]'>, <class 'object'>)
+# revealed: (<class '<unknown>'>, <class 'tuple[Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Invalid)
 
 # Invalid: too many positional arguments
 # error: [too-many-positional-arguments] "Too many positional arguments to function `namedtuple`: expected 2, got 4"
@@ -452,7 +461,8 @@ from ty_extensions import reveal_mro
 # Both `typename` and `field_names` can be passed as keyword arguments
 NT1 = collections.namedtuple(typename="NT1", field_names="x y")
 reveal_type(NT1)  # revealed: <class 'NT1'>
-reveal_mro(NT1)  # revealed: (<class 'NT1'>, <class 'tuple[Any, Any]'>, <class 'object'>)
+# revealed: (<class 'NT1'>, <class 'tuple[Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(NT1)
 
 nt1 = NT1(1, 2)
 reveal_type(nt1.x)  # revealed: Any
@@ -461,7 +471,8 @@ reveal_type(nt1.y)  # revealed: Any
 # Only `field_names` as keyword argument
 NT2 = collections.namedtuple("NT2", field_names=["a", "b", "c"])
 reveal_type(NT2)  # revealed: <class 'NT2'>
-reveal_mro(NT2)  # revealed: (<class 'NT2'>, <class 'tuple[Any, Any, Any]'>, <class 'object'>)
+# revealed: (<class 'NT2'>, <class 'tuple[Any, Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(NT2)
 
 nt2 = NT2(1, 2, 3)
 reveal_type(nt2.a)  # revealed: Any
@@ -494,7 +505,8 @@ from ty_extensions import reveal_mro
 Point = collections.namedtuple("Point", ["x", "class", "_y", "z", "z"], rename=True)
 reveal_type(Point)  # revealed: <class 'Point'>
 reveal_type(Point.__new__)  # revealed: [Self](cls: type[Self], x: Any, _1: Any, _2: Any, z: Any, _4: Any) -> Self
-reveal_mro(Point)  # revealed: (<class 'Point'>, <class 'tuple[Any, Any, Any, Any, Any]'>, <class 'object'>)
+# revealed: (<class 'Point'>, <class 'tuple[Any, Any, Any, Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Point)
 p = Point(1, 2, 3, 4, 5)
 reveal_type(p.x)  # revealed: Any
 reveal_type(p._1)  # revealed: Any
@@ -534,7 +546,8 @@ Person = collections.namedtuple("Person", ["name", "age", "city"], defaults=["Un
 reveal_type(Person)  # revealed: <class 'Person'>
 reveal_type(Person.__new__)  # revealed: [Self](cls: type[Self], name: Any, age: Any, city: Any = "Unknown") -> Self
 
-reveal_mro(Person)  # revealed: (<class 'Person'>, <class 'tuple[Any, Any, Any]'>, <class 'object'>)
+# revealed: (<class 'Person'>, <class 'tuple[Any, Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Person)
 # Can create with all fields
 person1 = Person("Alice", 30, "NYC")
 # Can omit the field with default
@@ -556,14 +569,16 @@ reveal_type(TooManyDefaults.__new__)  # revealed: [Self](cls: type[Self], x: Any
 # error: [unknown-argument]
 Bad1 = collections.namedtuple("Bad1", ["x", "y"], foobarbaz=42)
 reveal_type(Bad1)  # revealed: <class 'Bad1'>
-reveal_mro(Bad1)  # revealed: (<class 'Bad1'>, <class 'tuple[Any, Any]'>, <class 'object'>)
+# revealed: (<class 'Bad1'>, <class 'tuple[Any, Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Bad1)
 
 # Multiple unknown keyword arguments
 # error: [unknown-argument]
 # error: [unknown-argument]
 Bad2 = collections.namedtuple("Bad2", ["x"], invalid1=True, invalid2=False)
 reveal_type(Bad2)  # revealed: <class 'Bad2'>
-reveal_mro(Bad2)  # revealed: (<class 'Bad2'>, <class 'tuple[Any]'>, <class 'object'>)
+# revealed: (<class 'Bad2'>, <class 'tuple[Any]'>, <class 'Sequence[Any]'>, <class 'Reversible[Any]'>, <class 'Collection[Any]'>, <class 'Iterable[Any]'>, <class 'Container[Any]'>, typing.Protocol, typing.Generic, <class 'object'>)
+reveal_mro(Bad2)
 
 # Invalid type for `defaults` (not Iterable[Any] | None)
 # error: [invalid-argument-type] "Invalid argument to parameter `defaults` of `namedtuple()`"

crates/ty_python_semantic/src/types/class.rs

@@ -5497,23 +5497,26 @@ impl<'db> DynamicNamedTupleLiteral<'db> {
 
     /// Compute the MRO for this namedtuple.
     ///
-    /// The MRO is `[self, tuple[field_types...], object]`.
-    /// For example, `namedtuple("Point", [("x", int), ("y", int)])` has MRO
-    /// `[Point, tuple[int, int], object]`.
+    /// The MRO is the MRO of the class's tuple base class, prepended by `self`.
+    /// For example, `namedtuple("Point", [("x", int), ("y", int)])` has the following MRO:
+    ///
+    /// 1. `<class 'Point'>`
+    /// 2. `<class 'tuple[int, int]'>`
+    /// 3. `<class 'Sequence[int]'>`
+    /// 4. `<class 'Reversible[int]'>`
+    /// 5. `<class 'Collection[int]'>`
+    /// 6. `<class 'Iterable[int]'>`
+    /// 7. `<class 'Container[int]'>`
+    /// 8. `typing.Protocol`
+    /// 9. `typing.Generic`
+    /// 10. `<class 'object'>`
     #[salsa::tracked(returns(ref), heap_size = ruff_memory_usage::heap_size)]
     pub(crate) fn mro(self, db: &'db dyn Db) -> Mro<'db> {
         let self_base = ClassBase::Class(ClassType::NonGeneric(self.into()));
         let tuple_class = self.tuple_base_class(db);
-        let object_class = KnownClass::Object
-            .to_class_literal(db)
-            .as_class_literal()
-            .expect("object should be a class literal")
-            .default_specialization(db);
-        Mro::from([
-            self_base,
-            ClassBase::Class(tuple_class),
-            ClassBase::Class(object_class),
-        ])
+        std::iter::once(self_base)
+            .chain(tuple_class.iter_mro(db))
+            .collect()
     }
 
     /// Get the metaclass of this dynamic namedtuple.