[ty] Unify Type::is_subtype_of() and Type::is_assignable_to() (#18430)

crates/ty_python_semantic/resources/mdtest/intersection_types.md

@@ -305,10 +305,13 @@ simplify to `Never`, even in the presence of other types:
 
 ```py
 from ty_extensions import Intersection, Not
-from typing import Any
+from typing import Any, Generic, TypeVar
+
+T_co = TypeVar("T_co", covariant=True)
 
 class P: ...
 class Q: ...
+class R(Generic[T_co]): ...
 
 def _(
     i1: Intersection[P, Not[P]],
@@ -317,6 +320,8 @@ def _(
     i4: Intersection[Not[P], Q, P],
     i5: Intersection[P, Any, Not[P]],
     i6: Intersection[Not[P], Any, P],
+    i7: Intersection[R[P], Not[R[P]]],
+    i8: Intersection[R[P], Not[R[Q]]],
 ) -> None:
     reveal_type(i1)  # revealed: Never
     reveal_type(i2)  # revealed: Never
@@ -324,6 +329,8 @@ def _(
     reveal_type(i4)  # revealed: Never
     reveal_type(i5)  # revealed: Never
     reveal_type(i6)  # revealed: Never
+    reveal_type(i7)  # revealed: Never
+    reveal_type(i8)  # revealed: R[P] & ~R[Q]
 ```
 
 ### Union of a type and its negation
@@ -332,20 +339,28 @@ Similarly, if we have both `P` and `~P` in a _union_, we can simplify that to `o
 
 ```py
 from ty_extensions import Intersection, Not
+from typing import Generic, TypeVar
+
+T_co = TypeVar("T_co", covariant=True)
 
 class P: ...
 class Q: ...
+class R(Generic[T_co]): ...
 
 def _(
     i1: P | Not[P],
     i2: Not[P] | P,
     i3: P | Q | Not[P],
     i4: Not[P] | Q | P,
+    i5: R[P] | Not[R[P]],
+    i6: R[P] | Not[R[Q]],
 ) -> None:
     reveal_type(i1)  # revealed: object
     reveal_type(i2)  # revealed: object
     reveal_type(i3)  # revealed: object
     reveal_type(i4)  # revealed: object
+    reveal_type(i5)  # revealed: object
+    reveal_type(i6)  # revealed: R[P] | ~R[Q]
 ```
 
 ### Negation is an involution

crates/ty_python_semantic/resources/mdtest/protocols.md

@@ -902,8 +902,7 @@ from ty_extensions import is_subtype_of, is_assignable_to, static_assert, TypeOf
 class HasX(Protocol):
     x: int
 
-# TODO: this should pass
-static_assert(is_subtype_of(TypeOf[module], HasX))  # error: [static-assert-error]
+static_assert(is_subtype_of(TypeOf[module], HasX))
 static_assert(is_assignable_to(TypeOf[module], HasX))
 
 class ExplicitProtocolSubtype(HasX, Protocol):

crates/ty_python_semantic/resources/mdtest/type_properties/is_assignable_to.md

@@ -209,6 +209,34 @@ class AnyMeta(metaclass=Any): ...
 static_assert(is_assignable_to(type[AnyMeta], type))
 static_assert(is_assignable_to(type[AnyMeta], type[object]))
 static_assert(is_assignable_to(type[AnyMeta], type[Any]))
+
+from typing import TypeVar, Generic, Any
+
+T_co = TypeVar("T_co", covariant=True)
+
+class Foo(Generic[T_co]): ...
+class Bar(Foo[T_co], Generic[T_co]): ...
+
+static_assert(is_assignable_to(TypeOf[Bar[int]], type[Foo[int]]))
+static_assert(is_assignable_to(TypeOf[Bar[bool]], type[Foo[int]]))
+static_assert(is_assignable_to(TypeOf[Bar], type[Foo[int]]))
+static_assert(is_assignable_to(TypeOf[Bar[Any]], type[Foo[int]]))
+static_assert(is_assignable_to(TypeOf[Bar], type[Foo]))
+static_assert(is_assignable_to(TypeOf[Bar[Any]], type[Foo[Any]]))
+static_assert(is_assignable_to(TypeOf[Bar[Any]], type[Foo[int]]))
+
+# TODO: these should pass (all subscripts inside `type[]` type expressions are currently TODO types)
+static_assert(not is_assignable_to(TypeOf[Bar[int]], type[Foo[bool]]))  # error: [static-assert-error]
+static_assert(not is_assignable_to(TypeOf[Foo[bool]], type[Bar[int]]))  # error: [static-assert-error]
+```
+
+## `type[]` is not assignable to types disjoint from `builtins.type`
+
+```py
+from typing import Any
+from ty_extensions import is_assignable_to, static_assert
+
+static_assert(not is_assignable_to(type[Any], None))
 ```
 
 ## Class-literals that inherit from `Any`
@@ -717,6 +745,53 @@ def f(x: int, y: str) -> None: ...
 c1: Callable[[int], None] = partial(f, y="a")
 ```
 
+### Generic classes with `__call__`
+
+```toml
+[environment]
+python-version = "3.12"
+```
+
+```py
+from typing_extensions import Callable, Any, Generic, TypeVar, ParamSpec
+from ty_extensions import static_assert, is_assignable_to
+
+T = TypeVar("T")
+P = ParamSpec("P")
+
+class Foo[T]:
+    def __call__(self): ...
+
+class FooLegacy(Generic[T]):
+    def __call__(self): ...
+
+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`"
+    def __call__(self): ...
+
+static_assert(is_assignable_to(Foo, Callable[..., Any]))
+static_assert(is_assignable_to(FooLegacy, Callable[..., Any]))
+static_assert(is_assignable_to(Bar, Callable[..., Any]))
+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`"
+
+static_assert(not is_assignable_to(Spam, Callable[..., Any]))
+static_assert(not is_assignable_to(SpamLegacy, Callable[..., Any]))
+static_assert(not is_assignable_to(Eggs, Callable[..., Any]))
+
+# TODO: should pass
+static_assert(not is_assignable_to(EggsLegacy, Callable[..., Any]))  # error: [static-assert-error]
+```
+
 ### Classes with `__call__` as attribute
 
 An instance type is assignable to a compatible callable type if the instance type's class has a