unexpected "var-annotated" when using constrained TypeVar

[asottile-sentry]

Bug Report

I expect to not need to annotate the example below

To Reproduce

class C[T: (int, str)]:
    def __init__(self, x: T) -> None:
        self.x = x

Expected Behavior

no errors

Actual Behavior

$ ./venv/bin/mypy t.py
t.py:3: error: Need type annotation for "x"  [var-annotated]

Your Environment

• Mypy version used: 1.17.1
• Mypy command-line flags: n/a
• Mypy configuration options from mypy.ini (and other config files): n/a
• Python version used: 3.13.1

[sterliakov]

Yeah, this is a known problem. With constrained typevars mypy checks the body of function multiple times, once per constraint, and it's difficult to reconcile the results into inferred attr types reliably. Subset of #5416 (but maybe we should keep this open as having much better focus)