## Summary
Resolves https://github.com/astral-sh/ty/issues/1349.
Fix match statement value patterns to use equality comparison semantics
instead of incorrectly narrowing to literal types directly. Value
patterns use equality for matching, and equality can be overridden, so
we can't always narrow to the matched literal.
## Test Plan
Updated match.md with corrected expected types and an additional example
with explanation
---------
Co-authored-by: David Peter <mail@david-peter.de>
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## Summary
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This PR implements `F702`
https://docs.astral.sh/ruff/rules/continue-outside-loop/ as semantic
syntax error.
## Test Plan
<!-- How was it tested? -->
Tests are already previously written in F702
---------
Signed-off-by: 11happy <soni5happy@gmail.com>
## Summary
Part of astral-sh/ty#1341
The following changes will be made to `Place`.
* Introduce `TypeOrigin`
* `Place::Type` -> `Place::Defined`
* `Place::Unbound` -> `Place::Undefined`
* `Boundness` -> `Definedness`
`TypeOrigin::Declared`+`Definedness::PossiblyUndefined` are patterns
that weren't considered before, but this PR doesn't address them yet,
only refactors.
## Test Plan
Refactoring
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
`airflow.datasets.DatasetEvent` has been removed in 3 but `AssetEvent`
might be added in the future
## Test Plan
<!-- How was it tested? -->
update the test fixture and reorg in the second commit
Summary
--
Fixes#20844 by refining the unsupported syntax error check for [PEP
701]
f-strings before Python 3.12 to allow backslash escapes and escaped
outer quotes
in the format spec part of f-strings. These are only disallowed within
the
f-string expression part on earlier versions. Using the examples from
the PR:
```pycon
>>> f"{1:\x64}"
'1'
>>> f"{1:\"d\"}"
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: Invalid format specifier '"d"' for object of type 'int'
```
Note that the second case is a runtime error, but this is actually
avoidable if
you override `__format__`, so despite being pretty weird, this could
actually be
a valid use case.
```pycon
>>> class C:
... def __format__(*args, **kwargs): return "<C>"
...
>>> f"{C():\"d\"}"
'<C>'
```
At first I thought narrowing the range we check to exclude the format
spec would
only work for escapes, but it turns out that cases like `f"{1:""}"` are
already
covered by an existing `ParseError`, so we can just narrow the range of
both our
escape and quote checks.
Our comment check also seems to be working correctly because it's based
on the
actual tokens. A case like
[this](https://play.ruff.rs/9f1c2ff2-cd8e-4ad7-9f40-56c0a524209f):
```python
f"""{1:# }"""
```
doesn't include a comment token, instead the `#` is part of an
`InterpolatedStringLiteralElement`.
Test Plan
--
New inline parser tests
[PEP 701]: https://peps.python.org/pep-0701/
A large part of the diff on #20677 just involves threading a new
`inferable` parameter through all of the type property methods. In the
interests of making that PR easier to review, I've pulled that bit out
into here, so that it can be reviewed in isolation. This should be a
pure refactoring, with no logic changes or behavioral changes.
## Summary
Fixed a typo. It should be "or", not "of". Both `.pop()` and `next()` on
an empty collection will raise `IndexError`, not "`[0]` of the `pop()`
function"
## Test Plan
n/a
Summary
--
This PR implements the black preview style from
https://github.com/psf/black/pull/4720. As of Python 3.14, you're
allowed to omit the parentheses around groups of exceptions, as long as
there's no `as` binding:
**3.13**
```pycon
Python 3.13.4 (main, Jun 4 2025, 17:37:06) [Clang 20.1.4 ] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> try: ...
... except (Exception, BaseException): ...
...
Ellipsis
>>> try: ...
... except Exception, BaseException: ...
...
File "<python-input-1>", line 2
except Exception, BaseException: ...
^^^^^^^^^^^^^^^^^^^^^^^^
SyntaxError: multiple exception types must be parenthesized
```
**3.14**
```pycon
Python 3.14.0rc2 (main, Sep 2 2025, 14:20:56) [Clang 20.1.4 ] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> try: ...
... except Exception, BaseException: ...
...
Ellipsis
>>> try: ...
... except (Exception, BaseException): ...
...
Ellipsis
>>> try: ...
... except Exception, BaseException as e: ...
...
File "<python-input-2>", line 2
except Exception, BaseException as e: ...
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
SyntaxError: multiple exception types must be parenthesized when using 'as'
```
I think this ended up being pretty straightforward, at least once Micha
showed me where to start :)
Test Plan
--
New tests
At first I thought we were deviating from black in how we handle
comments within the exception type tuple, but I think this applies to
how we format all tuples, not specifically with the new preview style.
Summary
--
```shell
git clone git@github.com:psf/black.git ../other/black
crates/ruff_python_formatter/resources/test/fixtures/import_black_tests.py ../other/black
```
Then ran our tests and accepted the snapshots
I had to make a small fix to our tuple normalization logic for `del`
statements
in the second commit, otherwise the tests were panicking at a changed
AST. I
think the new implementation is closer to the intention described in the
nearby
comment anyway, though.
The first commit adds the new Python, settings, and `.expect` files, the
next three commits make some small
fixes to help get the tests running, and then the fifth commit accepts
all but one of the new snapshots. The last commit includes the new
unsupported syntax error for one f-string example, tracked in #20774.
Test Plan
--
Newly imported tests. I went through all of the new snapshots and added
review comments below. I think they're all expected, except a few cases
I wasn't 100% sure about.
## Summary
If a function is decorated with a decorator that returns a union of
`Callable`s, also treat it as a union of function-like `Callable`s.
Labeling as `internal`, since the previous change has not been released
yet.
## Test Plan
New regression test.
## Summary
Rename "unwrapping" methods on `Type` from e.g.
`Type::into_class_literal` to `Type::as_class_literal`. I personally
find that name more intuitive, since no transformation of any kind is
happening. We are just unwrapping from certain enum variants. An
alternative would be `try_as_class_literal`, which would follow the
[`strum` naming
scheme](https://docs.rs/strum/latest/strum/derive.EnumTryAs.html), but
is slightly longer.
Also rename `Type::into_callable` to `Type::try_upcast_to_callable`.
Note that I intentionally kept names like
`FunctionType::into_callable_type`, because those return `CallableType`,
not `Option<Type<…>>`.
## Test Plan
Pure refactoring
As part of #20598, we added `is_identical_to` methods to
`TypeVarInstance` and `BoundTypeVarInstance`, which compare when two
typevar instances refer to "the same" underlying typevar, even if we
have forced their lazy bounds/constraints as part of marking typevars as
inferable. (Doing so results in a different salsa interned struct ID,
since we've changed the contents of the `bounds_or_constraints` field.)
It turns out that marking typevars as inferable is not the only way that
we might force lazy bounds/constraints; it also happens when we
materialize a type containing a typevar. This surfaced as ecosystem
report failures on #20677.
That means that we need a more long-term fix to this problem.
(`is_identical_to`, and its underlying `original` field, were meant to
be a temporary fix until we removed the `MarkTypeVarsInferable` type
mapping.)
This PR extracts out a separate type (`TypeVarIdentity`) that only
includes the fields that actually inform whether two typevars are "the
same". All other properties of the typevar (default, bounds/constraints,
etc) still live in `TypeVarInstance`. Call sites that care about typevar
identity can now either store just `TypeVarIdentity` (if they never need
access to those other properties), or continue to store
`TypeVarInstance` but pull out its `identity` when performing those "are
they the same typevar" comparisons. (All of this also applies
respectively to `BoundTypeVar{Identity,Instance}`.) In particular,
constraint sets now work on `BoundTypeVarIdentity`, and generic contexts
still _store_ a `BoundTypeVarInstance` (since we might need access to
defaults when specializing), but are keyed on `BoundTypeVarIdentity`.
Generic classes are not allowed to bind or reference a typevar from an
enclosing scope:
```py
def f[T](x: T, y: T) -> None:
class Ok[S]: ...
# error: [invalid-generic-class]
class Bad1[T]: ...
# error: [invalid-generic-class]
class Bad2(Iterable[T]): ...
class C[T]:
class Ok1[S]: ...
# error: [invalid-generic-class]
class Bad1[T]: ...
# error: [invalid-generic-class]
class Bad2(Iterable[T]): ...
```
It does not matter if the class uses PEP 695 or legacy syntax. It does
not matter if the enclosing scope is a generic class or function. The
generic class cannot even _reference_ an enclosing typevar in its base
class list.
This PR adds diagnostics for these cases.
In addition, the PR adds better fallback behavior for generic classes
that violate this rule: any enclosing typevars are not included in the
class's generic context. (That ensures that we don't inadvertently try
to infer specializations for those typevars in places where we
shouldn't.) The `dulwich` ecosystem project has [examples of
this](d912eaaffd/dulwich/config.py (L251))
that were causing new false positives on #20677.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
This PR implements https://docs.astral.sh/ruff/rules/break-outside-loop/
(F701) as a semantic syntax error.
## Test Plan
<!-- How was it tested? -->
---------
Signed-off-by: 11happy <soni5happy@gmail.com>
Co-authored-by: Brent Westbrook <brentrwestbrook@gmail.com>
## Summary
Treat `Callable`s as bound-method descriptors if `Callable` is the
return type of a decorator that is applied to a function definition. See
the [rendered version of the new test
file](https://github.com/astral-sh/ruff/blob/david/callables-as-descriptors/crates/ty_python_semantic/resources/mdtest/call/callables_as_descriptors.md)
for the full description of this new heuristic.
I could imagine that we want to treat `Callable`s as bound-method
descriptors in other cases as well, but this seems like a step in the
right direction. I am planning to add other "use cases" from
https://github.com/astral-sh/ty/issues/491 to this test suite.
partially addresses https://github.com/astral-sh/ty/issues/491
closes https://github.com/astral-sh/ty/issues/1333
## Ecosystem impact
All positive
* 2961 removed `unsupported-operator` diagnostics on `sympy`, which was
one of the main motivations for implementing this change
* 37 removed `missing-argument` diagnostics, and no added call-error
diagnostics, which is an indicator that this heuristic shouldn't cause
many false positives
* A few removed `possibly-missing-attribute` diagnostics when accessing
attributes like `__name__` on decorated functions. The two added
`unused-ignore-comment` diagnostics are also cases of this.
* One new `invalid-assignment` diagnostic on `dd-trace-py`, which looks
suspicious, but only because our `invalid-assignment` diagnostics are
not great. This is actually a "Implicit shadowing of function"
diagnostic that hides behind the `invalid-assignment` diagnostic,
because a module-global function is being patched through a
`module.func` attribute assignment.
## Test Plan
New Markdown tests.
This PR resolves the issue noticed in
https://github.com/astral-sh/ruff/pull/20777#discussion_r2417233227.
Namely, cases like this were being flagged as syntax errors despite
being perfectly valid on Python 3.8:
```pycon
Python 3.8.20 (default, Oct 2 2024, 16:34:12)
[Clang 18.1.8 ] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> with (open("foo.txt", "w")): ...
...
Ellipsis
>>> with (open("foo.txt", "w")) as f: print(f)
...
<_io.TextIOWrapper name='foo.txt' mode='w' encoding='UTF-8'>
```
The second of these was already allowed but not the first:
```shell
> ruff check --target-version py38 --ignore ALL - <<EOF
with (open("foo.txt", "w")): ...
with (open("foo.txt", "w")) as f: print(f)
EOF
invalid-syntax: Cannot use parentheses within a `with` statement on Python 3.8 (syntax was added in Python 3.9)
--> -:1:6
|
1 | with (open("foo.txt", "w")): ...
| ^
2 | with (open("foo.txt", "w")) as f: print(f)
|
Found 1 error.
```
There was some discussion of related cases in
https://github.com/astral-sh/ruff/pull/16523#discussion_r1984657793, but
it seems I overlooked the single-element case when flagging tuples. As
suggested in the other thread, we can just check if there's more than
one element or a trailing comma, which will cause the tuple parsing on
<=3.8 and avoid the false positives.
## Summary
Based on the suggestion in
https://github.com/astral-sh/ruff/issues/20774#issuecomment-3383153511,
I added rendering of unsupported syntax errors in our `format` test.
In support of this, I added a `DummyFileResolver` type to `ruff_db` to
pass to `DisplayDiagnostics::new` (first commit). Another option would
obviously be implementing this directly in the fixtures, but we'd have
to import a `NotebookIndex` somehow; either by depending directly on
`ruff_notebook` or re-exporting it from `ruff_db`. I thought it might be
convenient elsewhere to have a dummy resolver, for example in the
parser, where we currently have a separate rendering pipeline
[copied](https://github.com/astral-sh/ruff/blob/main/crates/ruff_python_parser/tests/fixtures.rs#L321)
from our old rendering code in `ruff_linter`. I also briefly tried
implementing a `TestDb` in the formatter since I noticed the
`ruff_python_formatter::db` module, but that was turning into a lot more
code than the dummy resolver.
We could also push this a bit further if we wanted. I didn't add the new
snapshots to the black compatibility tests or to the preview snapshots,
for example. I thought it was kind of noisy enough (and helpful enough)
already, though. We could also use a shorter diagnostic format, but the
full output seems most useful once we accept this initial large batch of
changes.
## Test Plan
I went through the baseline snapshots pretty quickly, but they all
looked reasonable to me, with one exception I noted below. I also tested
that the case from #20774 produces a new unsupported syntax error.
## Summary
Move the `class_member` function to the `member` module. This allows us
to move the `member` module into the `types` module and to reduce the
visibility of its contents to `pub(super)`. The drawback is that we need
to make `place::place_by_id` public.
## Test Plan
Pure refactoring.
## Summary
When accessing an (instance) attribute on a given class, we were
previously traversing its MRO, and building a union of types (if the
attribute was available on multiple classes in the MRO) until we found a
*definitely bound* symbol. The idea was that possibly unbound symbols in
a subclass might only partially shadow the underlying base class
attribute.
This behavior was problematic for two reasons:
* if the attribute was definitely bound on a class (e.g. `self.x =
None`), we would have stopped iterating, even if there might be a `x:
str | None` declaration in a base class (the bug reported in
https://github.com/astral-sh/ty/issues/1067).
* if the attribute originated from an implicit instance attribute
assignment (e.g. `self.x = 1` in method `Sub.foo`), we might stop
looking and miss another implicit instance attribute assignment in a
base class method (e.g. `self.x = 2` in method `Base.bar`).
With this fix, we still iterate the MRO of the class, but we only stop
iterating if we find a *definitely declared* symbol. In this case, we
only return the declared attribute type. Otherwise, we keep building a
union of inferred attribute types.
The implementation here seemed to be the easiest fix for
https://github.com/astral-sh/ty/issues/1067 that also kept the ecosystem
impact low (the changes that I see all look correct). However, as the
Markdown tests show, there are other things to fix in this area. For
example, we should do a similar thing for *class attributes*. This is
more involved, though (affects many different areas and probably
involves a change to our descriptor protocol implementation), so I'd
like to postpone this to a follow-up.
closes https://github.com/astral-sh/ty/issues/1067
## Test Plan
Updated Markdown tests, including a regression test for
https://github.com/astral-sh/ty/issues/1067.
## Summary
Implements bidirectional type inference using function return type
annotations.
This PR was originally proposed to solve astral-sh/ty#1167, but this
does not fully resolve it on its own.
Additionally, I believe we need to allow dataclasses to generate their
own `__new__` methods, [use constructor return types for
inference](5844c0103d/crates/ty_python_semantic/src/types.rs (L5326-L5328)),
and a mechanism to discard type narrowing like `& ~AlwaysFalsy` if
necessary (at a more general level than this PR).
## Test Plan
`mdtest/bidirectional.md` is added.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Ibraheem Ahmed <ibraheem@ibraheem.ca>
## Summary
Resolves#19384.
- Distinguishes more clearly between `date` and `datetime` objects.
- Uniformly links to the relevant Python docs from rules in this
category.
I've tried to be clearer, but there's still a contradiction in the rules
as written: we say "use timezone-aware objects", but `date`s are
inherently timezone-naive.
Also, the full docs don't always match the error message: for instance,
in [DTZ012](https://docs.astral.sh/ruff/rules/call-date-fromtimestamp/),
the example says to use:
```python
datetime.datetime.fromtimestamp(946684800, tz=datetime.UTC)
```
while `fix_title` returns "Use `datetime.datetime.fromtimestamp(ts,
tz=...)**.date()**` instead".
I have left this as it was for now.
## Test Plan
Ran `mkdocs` locally and inspected result.
## Summary
Adds a set of basic new tests corresponding to open points in
https://github.com/astral-sh/ty/issues/1327, to document the state of
support for `dataclass_transform`.
## Summary
Type annotations are deferred by default starting with Python 3.14. No
`from __future__ import annotations` import is necessary.
## Test Plan
New Markdown test
## Summary
Simplify and fix the implementation of
`ty_extensions.CallableTypeOf[..]`.
closes https://github.com/astral-sh/ty/issues/1331
## Test Plan
Added regression test.
