As described in astral-sh/ty#1729, we previously had a salsa cycle when
inferring the signature of many function definitions.
The most obvious case happened when (a) the function was decorated, (b)
it had no PEP-695 type params, and (c) annotations were not always
deferred (e.g. in a stub file). We currently evaluate and apply function
decorators eagerly, as part of `infer_function_definition`. Applying a
decorator requires knowing the signature of the function being
decorated. There were two places where signature construction called
`infer_definition_types` cyclically.
The simpler case was that we were looking up the generic context and
decorator list of the function to determine whether it has an implicit
`self` parameter. Before, we used `infer_definition_types` to determine
that information. But since we're in the middle of signature
construction for the function, we can just thread the information
through directly.
The harder case is that signature construction requires knowing the
inferred parameter and return type annotations. When (b) and (c) hold,
those type annotations are inferred in `infer_function_definition`! (In
theory, we've already finished that by the time we start applying
decorators, but signature construction doesn't know that.)
If annotations are deferred, the params/return annotations are inferred
in `infer_deferred_types`; if there are PEP-695 type params, they're
inferred in `infer_function_type_params`. Both of those are different
salsa queries, and don't induce this cycle.
So the quick fix here is to always defer inference of the function
params/return, so that they are always inferred under a different salsa
query.
A more principled fix would be to apply decorators lazily, just like we
construct signatures lazily. But that is a more invasive fix.
Fixesastral-sh/ty#1729
---------
Co-authored-by: Alex Waygood <alex.waygood@gmail.com>
## Summary
Ignores `#ruff:isort` when parsing suppressions similar to `#ruff:noqa`.
Should clear up ecosystem issues in #21908
## Test Plan
cargo tests
Partially addresses https://github.com/astral-sh/ty/issues/1732
Fixes https://github.com/astral-sh/ty/issues/1800
## Summary
At each fixpoint iteration, we union the "previous" and "current"
iteration types, to ensure that the type can only widen at each
iteration. This prevents oscillation and ensures convergence.
But some unions triggered by this behavior (in particular, unions of
differently-specialized generic-aliases of the same class) never
simplify, and cause spurious errors. Since we haven't seen examples of
oscillating types involving class-literal or generic-alias types, just
don't union those.
There may be more thorough/principled ways to avoid undesirable unions
in fixpoint iteration, but this narrow change seems like it results in
strict improvement.
## Test Plan
Removes two false positive `unsupported-class-base` in mdtests, and
several in the ecosystem, without causing other regression.
I recently started noticing this showing up in the logs for every scope
based completion request:
```
2025-12-11 11:25:35.704329935 DEBUG request{id=29 method="textDocument/completion"}:map_stub_definition: Module `builtins` not found while looking in parent dirs
```
And in particular, it was repeated several times. This was confusing to
me because, well, of course `builtins` should resolve.
This particular code path comes from looking for the docstrings
of completion items. This involves a spelunking that ultimately
tries to resolve a "real" module if the stub doesn't have available
docstrings. But I guess there is no "real" `builtins` module, so
`resolve_real_module` fails. Which is fine, but the noisy logs were
annoying since this is an expected case.
So here, we carve out a short circuit for `builtins` and also improve
the log message.
These routines don't return *all* symbols/members, but rather,
only *for* a particular scope. We do specifically want to add
some routines that return *all* symbols/members, and this naming
scheme made that confusing. It was also inconsistent with other
routines like `all_end_of_scope_symbol_declarations` which *do*
return *all* symbols.
This PR improves the overload call resolution tracing messages as:
- Use `trace` level instead of `debug` level
- Add a `trace_span` which contains the call arguments and signature
- Remove the signature from individual tracing messages
## Summary
We currently perform a subtyping check, similar to what we were doing
for `@final` instances before
https://github.com/astral-sh/ruff/pull/21167, which is incorrect, e.g.
we currently consider `type[X[Any]]` and `type[X[T]]]` disjoint (where
`X` is `@final`).
This fixes the logic error that @sharkdp
[found](https://github.com/astral-sh/ruff/pull/21871#discussion_r2605755588)
in the constraint set upper bound normalization logic I introduced in
#21871.
I had originally claimed that `(T ≤ α & ~β)` should simplify into `(T ≤
α) ∧ ¬(T ≤ β)`. But that also suggests that `T ≤ ~β` should simplify to
`¬(T ≤ β)` on its own, and that's not correct.
The correct simplification is that `~α` is an "atomic" type, not an
"intersection" for the purposes of our upper bound simplifcation. So `(T
≤ α & ~β)` should simplify to `(T ≤ α) ∧ (T ≤ ~β)`. That is, break apart
the elements of a (proper) intersection, regardless of whether each
element is negated or not.
This PR fixes the logic, adds a test case, and updates the comments to
be hopefully more clear and accurate.
Fixes https://github.com/astral-sh/ty/issues/1832, fixes
https://github.com/astral-sh/ty/issues/1513
## Summary
A class object `C` (for which we infer an unspecialized `ClassLiteral`
type) should always be assignable to the type `type[C]` (which is
default-specialized, if `C` is generic). We already implemented this for
most cases, but we missed the case of a generic final type, where we
simplify `type[C]` to the `GenericAlias` type for the default
specialization of `C`. So we also need to implement this assignability
of generic `ClassLiteral` types as-if default-specialized.
## Test Plan
Added mdtests that failed before this PR.
---------
Co-authored-by: David Peter <mail@david-peter.de>
## Summary
Respect typevar bounds and constraints when matching against a union.
For example:
```py
def accepts_t_or_int[T_str: str](x: T_str | int) -> T_str:
raise NotImplementedError
reveal_type(accepts_t_or_int("a")) # ok, reveals `Literal["a"]`
reveal_type(accepts_t_or_int(1)) # ok, reveals `Unknown`
class Unrelated: ...
# error: [invalid-argument-type] "Argument type `Unrelated` does not
# satisfy upper bound `str` of type variable `T_str`"
accepts_t_or_int(Unrelated())
```
Previously, the last call succeed without any errors. Worse than that,
we also incorrectly solved `T_str = Unrelated`, which often lead to
downstream errors.
closes https://github.com/astral-sh/ty/issues/1837
## Ecosystem impact
Looks good!
* Lots of removed false positives, often because we previously selected
a wrong overload for a generic function (because we didn't respect the
typevar bound in an earlier overload).
* We now understand calls to functions accepting an argument of type
`GenericPath: TypeAlias = AnyStr | PathLike[AnyStr]`. Previously, we
would incorrectly match a `Path` argument against the `AnyStr` typevar
(violating its constraints), but now we match against `PathLike`.
## Performance
Another regression on `colour`. This package uses `numpy` heavily. And
`numpy` is the codebase that originally lead me to this bug. The fix
here allows us to infer more precise `np.array` types in some cases, so
it's reasonable that we just need to perform more work.
The fix here also requires us to look at more union elements when we
would previously short-circuit incorrectly, so some more work needs to
be done in the solver.
## Test Plan
New Markdown tests
This hack was introduced to reduce the amount of warnings that users
would get while transitioning to the new settings format
(https://github.com/astral-sh/ruff/pull/19787) but now that we're near
the beta release, it would be good to remove this.
In a constraint set, it's not useful for an upper bound to be an
intersection type, or for a lower bound to be a union type. Both of
those can be rewritten as simpler BDDs:
```
T ≤ α & β ⇒ (T ≤ α) ∧ (T ≤ β)
T ≤ α & ¬β ⇒ (T ≤ α) ∧ ¬(T ≤ β)
α | β ≤ T ⇒ (α ≤ T) ∧ (β ≤ T)
```
We were seeing performance issues on #21551 when _not_ performing this
simplification. For instance, `pandas` was producing some constraint
sets involving intersections of 8-9 different types. Our sequent map
calculation was timing out calculating all of the different permutations
of those types:
```
t1 & t2 & t3 → t1
t1 & t2 & t3 → t2
t1 & t2 & t3 → t3
t1 & t2 & t3 → t1 & t2
t1 & t2 & t3 → t1 & t3
t1 & t2 & t3 → t2 & t3
```
(and then imagine what that looks like for 9 types instead of 3...)
With this change, all of those permutations are now encoded in the BDD
structure itself, which is very good at simplifying that kind of thing.
Pulling this out of #21551 for separate review.
#21744 fixed some non-determinism in our constraint set implementation
by switching our BDD representation from being "fully reduced" to being
"quasi-reduced". We still deduplicate identical nodes (via salsa
interning), but we removed the logic to prune redundant nodes (one with
identical outgoing true and false edges). This ensures that the BDD
"remembers" all of the individual constraints that it was created with.
However, that comes at the cost of creating larger BDDs, and on #21551
that was causing performance issues. `scikit-learn` was producing a
function signature with dozens of overloads, and we were trying to
create a constraint set that would map a return type typevar to any of
those overload's return types. This created a combinatorial explosion in
the BDD, with by far most of the BDD paths leading to the `never`
terminal.
This change updates the quasi-reduction logic to prune nodes that are
redundant _because both edges lead to the `never` terminal_. In this
case, we don't need to "remember" that constraint, since no assignment
to it can lead to a valid specialization. So we keep the "memory" of our
quasi-reduced structure, while still pruning large unneeded portions of
the BDD structure.
Pulling this out of https://github.com/astral-sh/ruff/pull/21551 for
separate review.
## Summary
This is a follow-up to #21868. As soon as I started merging #21868 into
#21385, I realized that I had missed a test case with `**kwargs` after
the `*args` parameter. Such a case is supposed to be formatted on one
line like:
```py
# input
(
lambda
# comment
*x,
**y: x
)
# output
(
lambda
# comment
*x, **y: x
)
```
which you can still see on the
[playground](https://play.ruff.rs/bd88d339-1358-40d2-819f-865bfcb23aef?secondary=Format),
but on `main` after #21868, this was formatted as:
```py
(
lambda
# comment
*x,
**y: x
)
```
because the leading comment on the first parameter caused the whole
group around the parameters to break.
Instead of making these comments leading comments on the first
parameter, this PR makes them leading comments on the parameters list as
a whole.
## Test Plan
New tests, and I will also try merging this into #21385 _before_ opening
it for review this time.
<hr>
(labeling `internal` since #21868 should not be released before some
kind of fix)
## Summary
This PR adds special handling for `asynccontextmanager` calls as a
temporary solution for https://github.com/astral-sh/ty/issues/1804. We
will be able to remove this soon once we have support for generic
protocols in the solver.
closes https://github.com/astral-sh/ty/issues/1804
## Ecosystem
```diff
+ tests/test_downloadermiddleware.py:305:56: error[invalid-argument-type] Argument to bound method `download` is incorrect: Expected `Spider`, found `Unknown | Spider | None`
+ tests/test_downloadermiddleware.py:305:56: warning[possibly-missing-attribute] Attribute `spider` may be missing on object of type `Crawler | None`
```
These look like true positives
```diff
+ pymongo/asynchronous/database.py:1021:35: error[invalid-assignment] Object of type `(AsyncClientSession & ~AlwaysTruthy & ~AlwaysFalsy) | (_ServerMode & ~AlwaysFalsy) | Unknown | Primary` is not assignable to `_ServerMode | None`
+ pymongo/asynchronous/database.py:1025:17: error[invalid-argument-type] Argument to bound method `_conn_for_reads` is incorrect: Expected `_ServerMode`, found `_ServerMode | None`
```
Known problems or true positives, just caused by the new type for
`session`
```diff
- src/integrations/prefect-sqlalchemy/prefect_sqlalchemy/database.py:269:16: error[invalid-return-type] Return type does not match returned value: expected `Connection | AsyncConnection`, found `_GeneratorContextManager[Unknown, None, None] | _AsyncGeneratorContextManager[Unknown, None] | Connection | AsyncConnection`
+ src/integrations/prefect-sqlalchemy/prefect_sqlalchemy/database.py:269:16: error[invalid-return-type] Return type does not match returned value: expected `Connection | AsyncConnection`, found `_GeneratorContextManager[Unknown, None, None] | _AsyncGeneratorContextManager[AsyncConnection, None] | Connection | AsyncConnection`
```
Just a more concrete type
```diff
- src/prefect/flow_engine.py:1277:24: error[missing-argument] No argument provided for required parameter `cls`
- src/prefect/server/api/server.py:696:49: error[missing-argument] No argument provided for required parameter `cls`
- src/prefect/task_engine.py:1426:24: error[missing-argument] No argument provided for required parameter `cls`
```
Good
## Test Plan
* Adapted and newly added Markdown tests
* Tested on internal codebase
Summary
--
This PR makes two changes to comment placement in lambda parameters.
First, we
now insert a line break if the first parameter has a leading comment:
```py
# input
(
lambda
* # comment 2
x:
x
)
# main
(
lambda # comment 2
*x: x
)
# this PR
(
lambda
# comment 2
*x: x
)
```
Note the missing space in the output from main. This case is currently
unstable
on main. Also note that the new formatting is more consistent with our
stable
formatting in cases where the lambda has its own dangling comment:
```py
# input
(
lambda # comment 1
* # comment 2
x:
x
)
# output
(
lambda # comment 1
# comment 2
*x: x
)
```
and when a parameter without a comment precedes the split `*x`:
```py
# input
(
lambda y,
* # comment 2
x:
x
)
# output
(
lambda y,
# comment 2
*x: x
)
```
This does change the stable formatting, but I think such cases are rare
(expecting zero hits in the ecosystem report), this fixes an existing
instability, and it should not change any code we've previously
formatted.
Second, this PR modifies the comment placement such that `# comment 2`
in these
outputs is still a leading comment on the parameter. This is also not
the case
on main, where it becomes a [dangling lambda
comment](https://play.ruff.rs/3b29bb7e-70e4-4365-88e0-e60fe1857a35?secondary=Comments).
This doesn't cause any
instability that I'm aware of on main, but it does cause problems when
trying to
adjust the placement of dangling lambda comments in #21385. Changing the
placement in this way should not affect any formatting here.
Test Plan
--
New lambda tests, plus existing tests covering the cases above with
multiple
comments around the parameters (see lambda.py 122-143, and 122-205 or so
more
broadly)
I also checked manually that the comments are now leading on the
parameter:
```shell
❯ cargo run --bin ruff_python_formatter -- --emit stdout --target-version 3.10 --print-comments <<EOF
(
lambda
# comment 2
*x: x
)
EOF
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.15s
Running `target/debug/ruff_python_formatter --emit stdout --target-version 3.10 --print-comments`
# Comment decoration: Range, Preceding, Following, Enclosing, Comment
21..32, None, Some((Parameters, 37..39)), (ExprLambda, 6..42), "# comment 2"
{
Node {
kind: Parameter,
range: 37..39,
source: `*x`,
}: {
"leading": [
SourceComment {
text: "# comment 2",
position: OwnLine,
formatted: true,
},
],
"dangling": [],
"trailing": [],
},
}
(
lambda
# comment 2
*x: x
)
```
But I didn't see a great place to put a test like this. Is there
somewhere I can assert this comment placement since it doesn't affect
any formatting yet? Or is it okay to wait until we use this in #21385?
Amethyst Reese
Douglas Creager
Micha Reiser
Carl Meyer
Andrew Gallant
Luca Chiodini
Brent Westbrook
Denys Zhak
David Peter
Charlie Marsh
Dhruv Manilawala
Ibraheem Ahmed
Jack O'Connor