## Summary
cf. https://github.com/astral-sh/ruff/pull/20962
In the following code, `foo` in the comprehension was not reported as
unresolved:
```python
# error: [unresolved-reference] "Name `foo` used when not defined"
foo
foo = [
# no error!
# revealed: Divergent
reveal_type(x) for _ in () for x in [foo]
]
baz = [
# error: [unresolved-reference] "Name `baz` used when not defined"
# revealed: Unknown
reveal_type(x) for _ in () for x in [baz]
]
```
In fact, this is a more serious bug than it looks: for `foo`,
[`explicit_global_symbol` is
called](6cc3393ccd/crates/ty_python_semantic/src/types/infer/builder.rs (L8052)),
causing a symbol that should actually be `Undefined` to be reported as
being of type `Divergent`.
This PR fixes this bug. As a result, the code in
`mdtest/regression/pr_20962_comprehension_panics.md` no longer panics.
## Test Plan
`corpus\cyclic_symbol_in_comprehension.py` is added.
New tests are added in `mdtest/comprehensions/basic.md`.
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
A lot of the bidirectional inference work relies on `dict` not being
assignable to `TypedDict`, so I think it makes sense to add this before
fully implementing https://github.com/astral-sh/ty/issues/1387.
## Summary
Adds type inference for list/dict/set comprehensions, including
bidirectional inference:
```py
reveal_type({k: v for k, v in [("a", 1), ("b", 2)]}) # dict[Unknown | str, Unknown | int]
squares: list[int | None] = [x for x in range(10)]
reveal_type(squares) # list[int | None]
```
## Ecosystem impact
I did spot check the changes and most of them seem like known
limitations or true positives. Without proper bidirectional inference,
we saw a lot of false positives.
## Test Plan
New Markdown tests
## Summary
We previously didn't understand `range` and wrote these custom
`IntIterable`/`IntIterator` classes for tests. We can now remove them
and make the tests shorter in some places.
## Summary
Add support for `async for` loops and async iterables.
part of https://github.com/astral-sh/ty/issues/151
## Ecosystem impact
```diff
- boostedblob/listing.py:445:54: warning[unused-ignore-comment] Unused blanket `type: ignore` directive
```
This is correct. We now find a true positive in the `# type: ignore`'d
code.
All of the other ecosystem hits are of the type
```diff
trio (https://github.com/python-trio/trio)
+ src/trio/_core/_tests/test_guest_mode.py:532:24: error[not-iterable] Object of type `MemorySendChannel[int] | MemoryReceiveChannel[int]` may not be iterable
```
The message is correct, because only `MemoryReceiveChannel` has an
`__aiter__` method, but `MemorySendChannel` does not. What's not correct
is our inferred type here. It should be `MemoryReceiveChannel[int]`, not
the union of the two. This is due to missing unpacking support for tuple
subclasses, which @AlexWaygood is working on. I don't think this should
block merging this PR, because those wrong types are already there,
without this PR.
## Test Plan
New Markdown tests and snapshot tests for diagnostics.
