## Summary
In Python, the annotations on `x` and `y` here have very different
treatment:
```python
def foo(x: int):
y: int
```
The `int` in `x: int` is a runtime-required annotation, because `x` gets
added to the function's `__annotations__`. You'll notice, for example,
that this fails:
```python
from typing import TYPE_CHECKING
if TYPE_CHECKING:
from foo import Bar
def f(x: Bar):
...
```
Because `Bar` is required to be available at runtime, not just at typing
time. Meanwhile, this succeeds:
```python
from typing import TYPE_CHECKING
if TYPE_CHECKING:
from foo import Bar
def f():
x: Bar = 1
f()
```
(Both cases are fine if you use `from __future__ import annotations`.)
Historically, we've tracked those annotations that are _not_
runtime-required via the semantic model's `ANNOTATION` flag. But
annotations that _are_ runtime-required have been treated as "type
definitions" that aren't annotations.
This causes problems for the flake8-future-annotations rules, which try
to detect whether adding `from __future__ import annotations` would
_allow_ you to rewrite a type annotation. We need to know whether we're
in _any_ type annotation, runtime-required or not, since adding `from
__future__ import annotations` will convert any runtime-required
annotation to a typing-only annotation.
This PR adds separate state to track these runtime-required annotations.
The changes in the test fixtures are correct -- these were false
negatives before.
Closes https://github.com/astral-sh/ruff/issues/5574.
bf4b96c5de