## Summary
`KnownInstance::instance_fallback` may return instances of supertypes.
For example, it returns an instance of `_SpecialForm` for `Literal`.
This means it can't be used on the right-hand side of `is_subtype_of`
relationships, because it might lead to false positives.
I can lead to false negatives on the left hand side of `is_subtype_of`,
but this is at least a known limitation. False negatives are fine for
most applications, but false positives can lead to wrong results in
intersection-simplification, for example.
closes#14731
## Test Plan
Added regression test
## Summary
Simplify tuples containing `Never` to `Never`:
```py
from typing import Never
def never() -> Never: ...
reveal_type((1, never(), "foo")) # revealed: Never
```
I should note that mypy and pyright do *not* perform this
simplification. I don't know why.
There is [only one
place](5137fcc9c8/crates/red_knot_python_semantic/src/types/infer.rs (L1477-L1484))
where we use `TupleType::new` directly (instead of `Type::tuple`, which
changes behavior here). This appears when creating `TypeVar`
constraints, and it looks to me like it should stay this way, because
we're using `TupleType` to store a list of constraints there, instead of
an actual type. We also store `tuple[constraint1, constraint2, …]` as
the type for the `constraint1, constraint2, …` tuple expression. This
would mean that we infer a type of `tuple[str, Never]` for the following
type variable constraints, without simplifying it to `Never`. This seems
like a weird edge case that's maybe not worth looking further into?!
```py
from typing import Never
# vvvvvvvvvv
def f[T: (str, Never)](x: T):
pass
```
## Test Plan
- Added a new unit test. Did not add additional Markdown tests as that
seems superfluous.
- Tested the example above using red knot, mypy, pyright.
- Verified that this allows us to remove `contains_never` from the
property tests
(https://github.com/astral-sh/ruff/pull/14178#discussion_r1866473192)
This PR improves on #14477 by:
- Ensuring user's do not require the module alias "__debug__", which is unassignable
- Validating the linter settings for
`lint.flake8-import-conventions.extend-aliases` (whereas previously we
only did this for `lint.flake8-import-conventions.aliases`).
Closes#14662
Resolves https://github.com/astral-sh/ruff/issues/14547 by delegating
narrowing to `E` for `bool(E)` where `E` is some expression.
This change does not include other builtin class constructors which
should also work in this position, like `int(..)` or `float(..)`, as the
original issue does not mention these. It should be easy enough to add
checks for these as well if we want to.
I don't see a lot of markdown tests for malformed input, maybe there's a
better place for the no args and too many args cases to go?
I did see after the fact that it looks like this task was intended for a
new hire.. my apologies. I got here from
https://github.com/astral-sh/ruff/issues/13694, which is marked
help-wanted.
---------
Co-authored-by: David Peter <mail@david-peter.de>
This PR extends the Decimal parsing used in [verbose-decimal-constructor
(FURB157)](https://docs.astral.sh/ruff/rules/verbose-decimal-constructor/)
to better handle non-finite `Decimal` objects, avoiding some false
negatives.
Closes#14587
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
## Summary
Seeing the fuzzing results from @dhruvmanila in #13778, I think we can
re-enable these tests. We also had one regression that would have been
caught by these tests, so there is some value in having them enabled.
## Summary
- Check if `hashlib` and `crypt` imports have been seen for `FURB181`
and `S324`
- Mark the fix for `FURB181` as safe: I think it was accidentally marked
as unsafe in the first place. The rule does not support user-defined
classes as the "fix safety" section suggests.
- Removed `hashlib._Hash`, as it's not part of the `hashlib` module.
<!-- What's the purpose of the change? What does it do, and why? -->
## Test Plan
Updated the test snapshots
## Summary
Closes: https://github.com/astral-sh/ruff/issues/14593
The final type of a variable after if-statement without explicit else
branch should be similar to having an explicit else branch.
## Test Plan
Originally failed test cases from the bug are added.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
`bool()` is equal to `False`, and we infer `Literal[False]` for it. Which
means that the test here will fail as soon as we treat the body of
this `if` as unreachable.
## Summary
This came up as part of #12927 when implementing
`SemanticModel::simulate_runtime_load`.
Should be fairly self-explanatory, if the scope returns a binding with
`BindingKind::Annotation` the bottom part of the loop gets skipped, so
there's no chance for `seen_function` to have been updated. So unless
there's something subtle going on here, like function scopes never
containing bindings with `BindingKind::Annotation`, this seems like a
bug.
## Test Plan
`cargo nextest run`
## Summary
This PR fixes a bug in the f-string formatting to not consider the
escaped newlines for `is_multiline`. This is done by checking if the
f-string is triple-quoted or not similar to normal string literals.
This is not required to be gated behind preview because the logic change
for `is_multiline` was added in
https://github.com/astral-sh/ruff/pull/14454.
## Test Plan
Add a test case which formats differently on `main`:
https://play.ruff.rs/ea3c55c2-f0fe-474e-b6b8-e3365e0ede5e
## Summary
This PR gets rid of the `requirements.in` and `requirements.txt` files
in the `scripts/fuzz-parser` directory, and replaces them with
`pyproject.toml` and `uv.lock` files. The script is renamed from
`fuzz-parser` to `py-fuzzer` (since it can now also be used to fuzz
red-knot as well as the parser, following
https://github.com/astral-sh/ruff/pull/14566), and moved from the
`scripts/` directory to the `python/` directory, since it's now a
(uv)-pip-installable project in its own right.
I've been resisting this for a while, because conceptually this script
just doesn't feel "complicated" enough to me for it to be a full-blown
package. However, I think it's time to do this. Making it a proper
package has several advantages:
- It means we can run it from the project root using `uv run` without
having to activate a virtual environment and ensure that all required
dependencies are installed into that environment
- Using a `pyproject.toml` file means that we can express that the
project requires Python 3.12+ to run properly; this wasn't possible
before
- I've been running mypy on the project locally when I've been working
on it or reviewing other people's PRs; now I can put the mypy config for
the project in the `pyproject.toml` file
## Test Plan
I manually tested that all the commands detailed in
`python/py-fuzzer/README.md` work for me locally.
---------
Co-authored-by: David Peter <sharkdp@users.noreply.github.com>
## Summary
fixes: #14608
The logic that was only applied for 3.12+ target version needs to be
applied for other versions as well.
## Test Plan
I've moved the existing test cases for 3.12 only to `f_string.py` so
that it's tested against the default target version.
I think we should probably enabled testing for two target version (pre
3.12 and 3.12) but it won't highlight any issue because the parser
doesn't consider this. Maybe we should enable this once we have target
version specific syntax errors in place
(https://github.com/astral-sh/ruff/issues/6591).
