## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Extend `flake8-builtins` to imports, lambda-arguments, and modules to be
consistent with original checker
[flake8_builtins](https://github.com/gforcada/flake8-builtins/blob/main/flake8_builtins.py).
closes#12540
## Details
- Implement builtin-import-shadowing (A004)
- Stop tracking imports shadowing in builtin-variable-shadowing (A001)
in preview mode.
- Implement builtin-lambda-argument-shadowing (A005)
- Implement builtin-module-shadowing (A006)
- Add new option `linter.flake8_builtins.builtins_allowed_modules`
## Test Plan
cargo test
## Summary
If an import is marked as "required", we should never flag it as unused.
In practice, this is rare, since required imports are typically used for
`__future__` annotations, which are always considered "used".
Closes https://github.com/astral-sh/ruff/issues/12458.
Now that we have builtins available, resolve some simple cases to the
right builtin type.
We should also adjust the display for types to include their module
name; that's not done yet here.
## Summary
This PR adds support for untitled files in the Red Knot project.
Refer to the [design
discussion](https://github.com/astral-sh/ruff/discussions/12336) for
more details.
### Changes
* The `parsed_module` always assumes that the `SystemVirtual` path is of
`PySourceType::Python`.
* For the module resolver, as suggested, I went ahead by adding a new
`SystemOrVendoredPath` enum and renamed `FilePathRef` to
`SystemOrVendoredPathRef` (happy to consider better names here).
* The `file_to_module` query would return if it's a
`FilePath::SystemVirtual` variant because a virtual file doesn't belong
to any module.
* The sync implementation for the system virtual path is basically the
same as that of system path except that it uses the
`virtual_path_metadata`. The reason for this is that the system
(language server) would provide the metadata on whether it still exists
or not and if it exists, the corresponding metadata.
For point (1), VS Code would use `Untitled-1` for Python files and
`Untitled-1.ipynb` for Jupyter Notebooks. We could use this distinction
to determine whether the source type is `Python` or `Ipynb`.
## Test Plan
Added test cases in #12526
Extend red-knot type inference to cover all syntax, so that inferring
types for a scope gives all expressions a type. This means we can run
the red-knot semantic lint on all Python code without panics. It also
means we can infer types for `builtins.pyi` without panics.
To keep things simple, this PR intentionally doesn't add any new type
inference capabilities: the expanded coverage is all achieved with
`Type::Unknown`. But this puts the skeleton in place for adding better
inference of all these language features.
I also had to add basic Salsa cycle recovery (with just `Type::Unknown`
for now), because some `builtins.pyi` definitions are cyclic.
To test this, I added a comprehensive corpus of test snippets sourced
from Cinder under [MIT
license](https://github.com/facebookincubator/cinder/blob/cinder/3.10/cinderx/LICENSE),
which matches Ruff's license. I also added to this corpus some
additional snippets for newer language features: all the
`27_func_generic_*` and `73_class_generic_*` files, as well as
`20_lambda_default_arg.py`, and added a test which runs semantic-lint
over all these files. (The test doesn't assert the test-corpus files are
lint-free; just that they are able to lint without a panic.)
## Summary
Right now, in the isort comment model, there's nowhere for trailing
comments on the _statement_ to go, as in:
```python
from mylib import (
MyClient,
MyMgmtClient,
) # some comment
```
If the comment is on the _alias_, we do preserve it, because we attach
it to the alias, as in:
```python
from mylib import (
MyClient,
MyMgmtClient, # some comment
)
```
Similarly, if the comment is trailing on an import statement
(non-`from`), we again attach it to the alias, because it can't be
parenthesized, as in:
```python
import foo # some comment
```
This PR adds logic to track and preserve those trailing comments.
We also no longer drop several other comments, like:
```python
from mylib import (
# some comment
MyClient
)
```
Closes https://github.com/astral-sh/ruff/issues/12487.
