Bounds and constraints of type variables cannot be generic #1839
Description
Summary
In the current Python type specification, bounds and constraints for type variables must be concrete types and cannot contain type variables (even though it's possible at runtime).
peps.python.org/pep-0695#type-parameter-scopes
So, all of the following cases should be reported as errors:
from typing import TypeVar
# OK
T1 = TypeVar("T1", bound=list[int])
T2 = TypeVar("T2", list[int], str)
U = TypeVar("U")
# error
T3 = TypeVar("T3", bound=U)
# error
T4 = TypeVar("T4", bound=list[U])
# error
T5 = TypeVar("T5", bound=list["T5"])
# error
T6 = TypeVar("T6", U, str)
# error
T7 = TypeVar("T7", list["T7"], str)# OK
def _[T: list[int]](): ...
def _[T: (list[int], str)](): ...
# error
def _[U, T: U](): ...
# error
def _[U, T: list[U]](): ...
# error
def _[T: list[T]](): ...
# error
def _[U, T: (U, str)](): ...
# error
def _[T: (list[T], str)](): ...However, this is difficult to implement straightforwardly in the current implementation of ty, because bounds/constraints on type variables are lazily evaluated.
Version
No response