[red-knot] Super-basic generic inference at call sites

crates/red_knot_python_semantic/resources/mdtest/call/methods.md

@@ -410,29 +410,19 @@ def does_nothing[T](f: T) -> T:
 
 class C:
     @classmethod
-    # TODO: no error should be emitted here (needs support for generics)
-    # error: [invalid-argument-type]
     @does_nothing
     def f1(cls: type[C], x: int) -> str:
         return "a"
-    # TODO: no error should be emitted here (needs support for generics)
-    # error: [invalid-argument-type]
+
     @does_nothing
     @classmethod
     def f2(cls: type[C], x: int) -> str:
         return "a"
 
-# TODO: All of these should be `str` (and not emit an error), once we support generics
-
-# error: [call-non-callable]
-reveal_type(C.f1(1))  # revealed: Unknown
-# error: [call-non-callable]
-reveal_type(C().f1(1))  # revealed: Unknown
-
-# error: [call-non-callable]
-reveal_type(C.f2(1))  # revealed: Unknown
-# error: [call-non-callable]
-reveal_type(C().f2(1))  # revealed: Unknown
+reveal_type(C.f1(1))  # revealed: str
+reveal_type(C().f1(1))  # revealed: str
+reveal_type(C.f2(1))  # revealed: str
+reveal_type(C().f2(1))  # revealed: str
 ```
 
 [functions and methods]: https://docs.python.org/3/howto/descriptor.html#functions-and-methods

crates/red_knot_python_semantic/resources/mdtest/generics/classes.md

@@ -13,17 +13,13 @@ class C[T]: ...
 A class that inherits from a generic class, and fills its type parameters with typevars, is generic:
 
 ```py
-# TODO: no error
-# error: [non-subscriptable]
 class D[U](C[U]): ...
 ```
 
 A class that inherits from a generic class, but fills its type parameters with concrete types, is
 _not_ generic:
 
 ```py
-# TODO: no error
-# error: [non-subscriptable]
 class E(C[int]): ...
 ```
 
@@ -57,33 +53,85 @@ class D(C[T]): ...
 
 (Examples `E` and `F` from above do not have analogues in the legacy syntax.)
 
-## Inferring generic class parameters
+## Specializing generic classes explicitly
 
 The type parameter can be specified explicitly:
 
 ```py
 class C[T]:
     x: T
 
-# TODO: no error
-# TODO: revealed: C[int]
-# error: [non-subscriptable]
-reveal_type(C[int]())  # revealed: C
+reveal_type(C[int]())  # revealed: C[int]
+```
+
+The specialization must match the generic types:
+
+```py
+# error: [too-many-positional-arguments] "Too many positional arguments to class `C`: expected 1, got 2"
+reveal_type(C[int, int]())  # revealed: Unknown
+```
+
+If the type variable has an upper bound, the specialized type must satisfy that bound:
+
+```py
+class Bounded[T: int]: ...
+class BoundedByUnion[T: int | str]: ...
+class IntSubclass(int): ...
+
+reveal_type(Bounded[int]())  # revealed: Bounded[int]
+reveal_type(Bounded[IntSubclass]())  # revealed: Bounded[IntSubclass]
+
+# error: [invalid-argument-type] "Object of type `str` cannot be assigned to parameter 1 (`T`) of class `Bounded`; expected type `int`"
+reveal_type(Bounded[str]())  # revealed: Unknown
+
+# error:  [invalid-argument-type] "Object of type `int | str` cannot be assigned to parameter 1 (`T`) of class `Bounded`; expected type `int`"
+reveal_type(Bounded[int | str]())  # revealed: Unknown
+
+reveal_type(BoundedByUnion[int]())  # revealed: BoundedByUnion[int]
+reveal_type(BoundedByUnion[IntSubclass]())  # revealed: BoundedByUnion[IntSubclass]
+reveal_type(BoundedByUnion[str]())  # revealed: BoundedByUnion[str]
+reveal_type(BoundedByUnion[int | str]())  # revealed: BoundedByUnion[int | str]
+```
+
+If the type variable is constrained, the specialized type must satisfy those constraints:
+
+```py
+class Constrained[T: (int, str)]: ...
+
+reveal_type(Constrained[int]())  # revealed: Constrained[int]
+
+# TODO: error: [invalid-argument-type]
+# TODO: revealed: Unknown
+reveal_type(Constrained[IntSubclass]())  # revealed: Constrained[IntSubclass]
+
+reveal_type(Constrained[str]())  # revealed: Constrained[str]
+
+# TODO: error: [invalid-argument-type]
+# TODO: revealed: Unknown
+reveal_type(Constrained[int | str]())  # revealed: Constrained[int | str]
+
+# error: [invalid-argument-type] "Object of type `object` cannot be assigned to parameter 1 (`T`) of class `Constrained`; expected type `int | str`"
+reveal_type(Constrained[object]())  # revealed: Unknown
 ```
 
+## Inferring generic class parameters
+
 We can infer the type parameter from a type context:
 
 ```py
+class C[T]:
+    x: T
+
 c: C[int] = C()
 # TODO: revealed: C[int]
-reveal_type(c)  # revealed: C
+reveal_type(c)  # revealed: C[Unknown]
 ```
 
 The typevars of a fully specialized generic class should no longer be visible:
 
 ```py
 # TODO: revealed: int
-reveal_type(c.x)  # revealed: T
+reveal_type(c.x)  # revealed: Unknown
 ```
 
 If the type parameter is not specified explicitly, and there are no constraints that let us infer a
@@ -92,15 +140,13 @@ specific type, we infer the typevar's default type:
 ```py
 class D[T = int]: ...
 
-# TODO: revealed: D[int]
-reveal_type(D())  # revealed: D
+reveal_type(D())  # revealed: D[int]
 ```
 
 If a typevar does not provide a default, we use `Unknown`:
 
 ```py
-# TODO: revealed: C[Unknown]
-reveal_type(C())  # revealed: C
+reveal_type(C())  # revealed: C[Unknown]
 ```
 
 If the type of a constructor parameter is a class typevar, we can use that to infer the type
@@ -111,7 +157,7 @@ class E[T]:
     def __init__(self, x: T) -> None: ...
 
 # TODO: revealed: E[int] or E[Literal[1]]
-reveal_type(E(1))  # revealed: E
+reveal_type(E(1))  # revealed: E[Unknown]
 ```
 
 The types inferred from a type context and from a constructor parameter must be consistent with each
@@ -131,17 +177,10 @@ propagate through:
 class Base[T]:
     x: T | None = None
 
-# TODO: no error
-# error: [non-subscriptable]
 class Sub[U](Base[U]): ...
 
-# TODO: no error
-# TODO: revealed: int | None
-# error: [non-subscriptable]
-reveal_type(Base[int].x)  # revealed: T | None
-# TODO: revealed: int | None
-# error: [non-subscriptable]
-reveal_type(Sub[int].x)  # revealed: T | None
+reveal_type(Base[int].x)  # revealed: int | None
+reveal_type(Sub[int].x)  # revealed: int | None
 ```
 
 ## Cyclic class definition
@@ -155,8 +194,6 @@ Here, `Sub` is not a generic class, since it fills its superclass's type paramet
 
 ```pyi
 class Base[T]: ...
-# TODO: no error
-# error: [non-subscriptable]
 class Sub(Base[Sub]): ...
 
 reveal_type(Sub)  # revealed: Literal[Sub]
@@ -168,9 +205,6 @@ A similar case can work in a non-stub file, if forward references are stringifie
 
 ```py
 class Base[T]: ...
-
-# TODO: no error
-# error: [non-subscriptable]
 class Sub(Base["Sub"]): ...
 
 reveal_type(Sub)  # revealed: Literal[Sub]
@@ -183,8 +217,6 @@ In a non-stub file, without stringified forward references, this raises a `NameE
 ```py
 class Base[T]: ...
 
-# TODO: the unresolved-reference error is correct, the non-subscriptable is not
-# error: [non-subscriptable]
 # error: [unresolved-reference]
 class Sub(Base[Sub]): ...
 ```

crates/red_knot_python_semantic/resources/mdtest/generics/functions.md

@@ -51,25 +51,10 @@ the inferred type to e.g. `int`.
 def f[T](x: T) -> T:
     return x
 
-# TODO: no error
-# TODO: revealed: int or Literal[1]
-# error: [invalid-argument-type]
-reveal_type(f(1))  # revealed: T
-
-# TODO: no error
-# TODO: revealed: float
-# error: [invalid-argument-type]
-reveal_type(f(1.0))  # revealed: T
-
-# TODO: no error
-# TODO: revealed: bool or Literal[true]
-# error: [invalid-argument-type]
-reveal_type(f(True))  # revealed: T
-
-# TODO: no error
-# TODO: revealed: str or Literal["string"]
-# error: [invalid-argument-type]
-reveal_type(f("string"))  # revealed: T
+reveal_type(f(1))  # revealed: Literal[1]
+reveal_type(f(1.0))  # revealed: float
+reveal_type(f(True))  # revealed: Literal[True]
+reveal_type(f("string"))  # revealed: Literal["string"]
 ```
 
 ## Inferring “deep” generic parameter types
@@ -82,7 +67,7 @@ def f[T](x: list[T]) -> T:
     return x[0]
 
 # TODO: revealed: float
-reveal_type(f([1.0, 2.0]))  # revealed: T
+reveal_type(f([1.0, 2.0]))  # revealed: Unknown
 ```
 
 ## Typevar constraints
@@ -162,61 +147,39 @@ parameters simultaneously.
 def two_params[T](x: T, y: T) -> T:
     return x
 
-# TODO: no error
 # TODO: revealed: str
-# error: [invalid-argument-type]
-# error: [invalid-argument-type]
-reveal_type(two_params("a", "b"))  # revealed: T
+reveal_type(two_params("a", "b"))  # revealed: Literal["a", "b"]
 
-# TODO: no error
 # TODO: revealed: str | int
-# error: [invalid-argument-type]
-# error: [invalid-argument-type]
-reveal_type(two_params("a", 1))  # revealed: T
+reveal_type(two_params("a", 1))  # revealed: Literal["a", 1]
 ```
 
 ```py
 def param_with_union[T](x: T | int, y: T) -> T:
     return y
 
-# TODO: no error
 # TODO: revealed: str
-# error: [invalid-argument-type]
-reveal_type(param_with_union(1, "a"))  # revealed: T
+reveal_type(param_with_union(1, "a"))  # revealed: Literal["a"]
 
-# TODO: no error
 # TODO: revealed: str
-# error: [invalid-argument-type]
-# error: [invalid-argument-type]
-reveal_type(param_with_union("a", "a"))  # revealed: T
+reveal_type(param_with_union("a", "a"))  # revealed: Literal["a"]
 
-# TODO: no error
 # TODO: revealed: int
-# error: [invalid-argument-type]
-reveal_type(param_with_union(1, 1))  # revealed: T
+reveal_type(param_with_union(1, 1))  # revealed: Literal[1]
 
-# TODO: no error
 # TODO: revealed: str | int
-# error: [invalid-argument-type]
-# error: [invalid-argument-type]
-reveal_type(param_with_union("a", 1))  # revealed: T
+reveal_type(param_with_union("a", 1))  # revealed: Literal["a", 1]
 ```
 
 ```py
 def tuple_param[T, S](x: T | S, y: tuple[T, S]) -> tuple[T, S]:
     return y
 
-# TODO: no error
 # TODO: revealed: tuple[str, int]
-# error: [invalid-argument-type]
-# error: [invalid-argument-type]
-reveal_type(tuple_param("a", ("a", 1)))  # revealed: tuple[T, S]
+reveal_type(tuple_param("a", ("a", 1)))  # revealed: tuple[Literal["a"], Literal[1]]
 
-# TODO: no error
 # TODO: revealed: tuple[str, int]
-# error: [invalid-argument-type]
-# error: [invalid-argument-type]
-reveal_type(tuple_param(1, ("a", 1)))  # revealed: tuple[T, S]
+reveal_type(tuple_param(1, ("a", 1)))  # revealed: tuple[Literal["a"], Literal[1]]
 ```
 
 ## Inferring nested generic function calls
@@ -231,15 +194,9 @@ def f[T](x: T) -> tuple[T, int]:
 def g[T](x: T) -> T | None:
     return x
 
-# TODO: no error
 # TODO: revealed: tuple[str | None, int]
-# error: [invalid-argument-type]
-# error: [invalid-argument-type]
-reveal_type(f(g("a")))  # revealed: tuple[T, int]
+reveal_type(f(g("a")))  # revealed: tuple[Literal["a"] | None, int]
 
-# TODO: no error
 # TODO: revealed: tuple[str, int] | None
-# error: [invalid-argument-type]
-# error: [invalid-argument-type]
-reveal_type(g(f("a")))  # revealed: T | None
+reveal_type(g(f("a")))  # revealed: tuple[Literal["a"], int] | None
 ```