Commit Graph

833 Commits

Author SHA1 Message Date
Douglas Creager 2897d498fd add TODO 2025-12-15 12:13:03 -05:00
Douglas Creager 4e3dd58815 fix Class3 example 2025-12-15 12:07:32 -05:00
Douglas Creager 26c847c229 add a bunch of callable reveals 2025-12-15 12:01:40 -05:00
Douglas Creager dfcdbcffec Merge remote-tracking branch 'origin/main' into dcreager/callable-return
* origin/main:
  Fluent formatting of method chains (#21369)
  [ty] Avoid stack overflow when calculating inferable typevars (#21971)
  [ty] Add "qualify ..." code fix for undefined references (#21968)
  [ty] Use jemalloc on linux (#21975)
  Update MSRV to 1.90 (#21987)
  [ty] Improve check enforcing that an overloaded function must have an implementation (#21978)
  Update actions/checkout digest to 8e8c483 (#21982)
  [ty] Use `ParamSpec` without the attr for inferable check (#21934)
  [ty] Emit diagnostic when a type variable with a default is followed by one without a default (#21787)
2025-12-15 11:06:49 -05:00
Douglas Creager f8a5d04296 Merge branch 'dcreager/source-order-constraints' into dcreager/callable-return
* dcreager/source-order-constraints: (30 commits)
  clippy
  fix test expectations (again)
  include source_order in display_graph output
  place bounds/constraints first
  don't always bump
  only fold once
  document display source_order
  more comments
  remove now-unused items
  fix test expectation
  use source order in specialize_constrained too
  document overall approach
  more comment
  reuse self source_order
  sort specialize_constrained by source_order
  lots of renaming
  remove source_order_for
  simpler source_order_for
  doc
  restore TODOs
  ...
2025-12-15 10:53:25 -05:00
Douglas Creager cbfecfaf41
[ty] Avoid stack overflow when calculating inferable typevars (#21971)
When we calculate which typevars are inferable in a generic context, the
result might include more than the typevars bound by the generic
context. The canonical example is a generic method of a generic class:

```py
class C[A]:
    def method[T](self, t: T): ...
```

Here, the inferable typevar set of `method` contains `Self` and `T`, as
you'd expect. (Those are the typevars bound by the method.) But it also
contains `A@C`, since the implicit `Self` typevar is defined as `Self:
C[A]`. That means when we call `method`, we need to mark `A@C` as
inferable, so that we can determine the correct mapping for `A@C` at the
call site.

Fixes https://github.com/astral-sh/ty/issues/1874
2025-12-15 10:25:33 -05:00
Douglas Creager 1dd3cf0e58 fix test expectations (again) 2025-12-15 10:22:27 -05:00
Douglas Creager da31e138b4 fix test expectation 2025-12-15 08:39:21 -05:00
Alex Waygood 0b918ae4d5
[ty] Improve check enforcing that an overloaded function must have an implementation (#21978)
## Summary

- Treat `if TYPE_CHECKING` blocks the same as stub files (the feature
requested in https://github.com/astral-sh/ty/issues/1216)
- We currently only allow `@abstractmethod`-decorated methods to omit
the implementation if they're methods in classes that have _exactly_
`ABCMeta` as their metaclass. That seems wrong -- `@abstractmethod` has
the same semantics if a class has a subclass of `ABCMeta` as its
metaclass. This PR fixes that too. (I'm actually not _totally_ sure we
should care what the class's metaclass is at all -- see discussion in
https://github.com/astral-sh/ty/issues/1877#issue-3725937441... but the
change this PR is making seems less wrong than what we have currently,
anyway.)

Fixes https://github.com/astral-sh/ty/issues/1216

## Test Plan

Mdtests and snapshots
2025-12-15 08:56:35 +00:00
Dhruv Manilawala ba47349c2e
[ty] Use `ParamSpec` without the attr for inferable check (#21934)
## Summary

fixes: https://github.com/astral-sh/ty/issues/1820

## Test Plan

Add new mdtests.

Ecosystem changes removes all false positives.
2025-12-15 11:04:28 +05:30
Bhuminjay Soni 04f9949711
[ty] Emit diagnostic when a type variable with a default is followed by one without a default (#21787)
Co-authored-by: Alex Waygood <alex.waygood@gmail.com>
2025-12-14 19:35:37 +00:00
Douglas Creager e583cb7682 restore TODOs 2025-12-14 13:11:31 -05:00
Douglas Creager 86271d605d codex 2 2025-12-14 13:10:51 -05:00
Douglas Creager 8655598901 codex attempt 1 2025-12-14 12:56:21 -05:00
Charlie Marsh be8eb92946
[ty] Add support for `__qualname__` and other implicit class attributes (#21966)
## Summary

Closes https://github.com/astral-sh/ty/issues/1873
2025-12-13 17:10:25 -05:00
Simon Lamon a544c59186
[ty] Emit a diagnostic when frozen dataclass inherits a non-frozen dataclass and the other way around (#21962)
Co-authored-by: Alex Waygood <alex.waygood@gmail.com>
2025-12-13 20:59:26 +00:00
Alex Waygood bb464ed924
[ty] Use unqualified names for displays of `TypeAliasType`s and unbound `ParamSpec`s/`TypeVar`s (#21960) 2025-12-13 20:23:16 +00:00
Douglas Creager 25a6690cdb add materialization test 2025-12-12 22:22:33 -05:00
Douglas Creager 99ec0be478 fix test 2025-12-12 22:22:33 -05:00
Douglas Creager c94fbe20a2 Merge remote-tracking branch 'origin/main' into gggg
* origin/main: (22 commits)
  [ty] Allow gradual lower/upper bounds in a constraint set (#21957)
  [ty] disallow explicit specialization of type variables themselves (#21938)
  [ty] Improve diagnostics for unsupported binary operations and unsupported augmented assignments (#21947)
  [ty] update implicit root docs (#21955)
  [ty] Enable even more goto-definition on inlay hints (#21950)
  Document known lambda formatting deviations from Black (#21954)
  [ty] fix hover type on named expression target (#21952)
  Bump benchmark dependencies (#21951)
  Keep lambda parameters on one line and parenthesize the body if it expands (#21385)
  [ty] Improve resolution of absolute imports in tests (#21817)
  [ty] Support `__all__ += submodule.__all__`
  [ty] Change frequency of invalid `__all__` debug message
  [ty] Add `KnownUnion::to_type()` (#21948)
  [ty] Classify `cls` as class parameter (#21944)
  [ty] Stabilize rename (#21940)
  [ty] Ignore `__all__` for document and workspace symbol requests
  [ty] Attach db to background request handler task (#21941)
  [ty] Fix outdated version in publish diagnostics after `didChange` (#21943)
  [ty] avoid fixpoint unioning of types containing current-cycle Divergent (#21910)
  [ty] improve bad specialization results & error messages (#21840)
  ...
2025-12-12 22:22:11 -05:00
Douglas Creager b413a6dec4
[ty] Allow gradual lower/upper bounds in a constraint set (#21957)
We now allow the lower and upper bounds of a constraint to be gradual.
Before, we would take the top/bottom materializations of the bounds.
This required us to pass in whether the constraint was intended for a
subtyping check or an assignability check, since that would control
whether we took the "restrictive" or "permissive" materializations,
respectively.

Unfortunately, doing so means that we lost information about whether the
original query involves a non-fully-static type. This would cause us to
create specializations like `T = object` for the constraint `T ≤ Any`,
when it would be nicer to carry through the gradual type and produce `T
= Any`.

We're not currently using constraint sets for subtyping checks, nor are
we going to in the very near future. So for now, we're going to assume
that constraint sets are always used for assignability checks, and allow
the lower/upper bounds to not be fully static. Once we get to the point
where we need to use constraint sets for subtyping checks, we will
consider how best to record this information in constraints.
2025-12-12 22:18:30 -05:00
Shunsuke Shibayama e19c050386
[ty] disallow explicit specialization of type variables themselves (#21938)
## Summary

This PR makes explicit specialization of a type variable itself an
error, and the result of the specialization is `Unknown`.

The change also fixes https://github.com/astral-sh/ty/issues/1794.

## Test Plan

mdtests updated
new corpus test

---------

Co-authored-by: Carl Meyer <carl@astral.sh>
2025-12-12 15:49:20 -08:00
Alex Waygood 5a2aba237b
[ty] Improve diagnostics for unsupported binary operations and unsupported augmented assignments (#21947)
## Summary

This PR takes the improvements we made to unsupported-comparison
diagnostics in https://github.com/astral-sh/ruff/pull/21737, and extends
them to other `unsupported-operator` diagnostics.

## Test Plan

Mdtests and snapshots
2025-12-12 21:53:29 +00:00
Douglas Creager 690310cea3 not needed anymore 2025-12-12 13:05:29 -05:00
Alex Waygood a722df6a73
[ty] Enable even more goto-definition on inlay hints (#21950)
## Summary

Working on py-fuzzer recently (AKA, a Python project!) reminded me how
cool our "inlay hint goto-definition feature" is. So this PR adds a
bunch more of that!

I also made a couple of other minor changes to type display. For
example, in the playground, this snippet:

```py
def f(): ...
reveal_type(f.__get__)
```

currently leads to this diagnostic:

```
Revealed type: `<method-wrapper `__get__` of `f`>` (revealed-type) [Ln 2, Col 13]
```

But the fact that we have backticks both around the type display and
inside the type display isn't _great_ there. This PR changes it to

```
Revealed type: `<method-wrapper '__get__' of function 'f'>` (revealed-type) [Ln 2, Col 13]
```

which avoids the nested-backticks issue in diagnostics, and is more
similar to our display for various other `Type` variants such as
class-literal types (`<class 'Foo'>`, etc., not ``<class `Foo`>``).

## Test Plan

inlay snapshots added; mdtests updated
2025-12-12 12:57:38 -05:00
Aria Desires d5546508cf
[ty] Improve resolution of absolute imports in tests (#21817)
By teaching desperate resolution to try every possible ancestor that
doesn't have an `__init__.py(i)` when resolving absolute imports.

* Fixes https://github.com/astral-sh/ty/issues/1782
2025-12-12 11:59:06 -05:00
Carl Meyer 0138cd238a
[ty] avoid fixpoint unioning of types containing current-cycle Divergent (#21910)
Partially addresses https://github.com/astral-sh/ty/issues/1732

## Summary

Don't union the previous type in fixpoint iteration if the previous type
contains a `Divergent` from the current cycle and the latest type does
not. The theory here, as outlined by @mtshiba at
https://github.com/astral-sh/ty/issues/1732#issuecomment-3609937420, is
that oscillation can't occur by removing and then reintroducing a
`Divergent` type repeatedly, since `Divergent` types are only introduced
at the start of fixpoint iteration.

## Test Plan

Removes a `Divergent` type from the added mdtest, doesn't otherwise
regress any tests.
2025-12-11 19:52:34 -08:00
Shunsuke Shibayama 5e42926eee
[ty] improve bad specialization results & error messages (#21840)
## Summary

This PR includes the following changes:

* When attempting to specialize a non-generic type (or a type that is
already specialized), the result is `Unknown`. Also, the error message
is improved.
* When an implicit type alias is incorrectly specialized, the result is
`Unknown`. Also, the error message is improved.
* When only some of the type alias bounds and constraints are not
satisfied, not all substitutions are `Unknown`.
* Double specialization is prohibited. e.g. `G[int][int]`

Furthermore, after applying this PR, the fuzzing tests for seeds 1052
and 4419, which panic in main, now pass.
This is because the false recursions on type variables have been
removed.

```python
# name_2[0] => Unknown
class name_1[name_2: name_2[0]]:
    def name_4(name_3: name_2, /):
        if name_3:
            pass

#  (name_5 if unique_name_0 else name_1)[0] => Unknown
def name_4[name_5: (name_5 if unique_name_0 else name_1)[0], **name_1](): ...
```

## Test Plan

New corpus test
mdtest files updated
2025-12-11 19:21:34 -08:00
Jack O'Connor ddb7645e9d
[ty] support `NewType`s of `float` and `complex` (#21886)
Fixes https://github.com/astral-sh/ty/issues/1818.
2025-12-12 00:43:09 +00:00
Douglas Creager f624bfdf63 clean up the diff 2025-12-11 16:21:30 -05:00
Douglas Creager bfde3e41a7 update tests 2025-12-11 16:09:33 -05:00
Douglas Creager a892be3124 Merge remote-tracking branch 'origin/main' into dcreager/callable-return
* origin/main: (36 commits)
  [ty] Defer all parameter and return type annotations (#21906)
  [ty] Fix workspace symbols to return members too (#21926)
  Document range suppressions, reorganize suppression docs (#21884)
  Ignore ruff:isort like ruff:noqa in new suppressions (#21922)
  [ty] Handle `Definition`s in `SemanticModel::scope` (#21919)
  [ty] Attach salsa db when running ide tests for easier debugging (#21917)
  [ty] Don't show hover for expressions with no inferred type (#21924)
  [ty] avoid unions of generic aliases of the same class in fixpoint (#21909)
  [ty] Squash false positive logs for failing to find `builtins` as a real module
  [ty] Uniformly use "not supported" in diagnostics (#21916)
  [ty] Reduce size of ty-ide snapshots (#21915)
  [ty] Adjust scope completions to use all reachable symbols
  [ty] Rename `all_members_of_scope` to `all_end_of_scope_members`
  [ty] Remove `all_` prefix from some routines on UseDefMap
  Enable `--document-private-items` for `ruff_python_formatter` (#21903)
  Remove `BackwardsTokenizer` based `parenthesized_range` references in `ruff_linter` (#21836)
  [ty] Revert "Do not infer types for invalid binary expressions in annotations" (#21914)
  Skip over trivia tokens after re-lexing (#21895)
  [ty] Avoid inferring types for invalid binary expressions in string annotations (#21911)
  [ty] Improve overload call resolution tracing (#21913)
  ...
2025-12-11 16:06:59 -05:00
Douglas Creager c8851ecf70
[ty] Defer all parameter and return type annotations (#21906)
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.

Fixes astral-sh/ty#1729

---------

Co-authored-by: Alex Waygood <alex.waygood@gmail.com>
2025-12-11 15:00:18 -05:00
Carl Meyer 4fdb4e8219
[ty] avoid unions of generic aliases of the same class in fixpoint (#21909)
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.
2025-12-11 09:53:43 -08:00
Luca Chiodini 5a9d6a91ea
[ty] Uniformly use "not supported" in diagnostics (#21916) 2025-12-11 15:03:55 +00:00
Charlie Marsh 5c320990f7
[ty] Avoid inferring types for invalid binary expressions in string annotations (#21911)
## Summary

Closes https://github.com/astral-sh/ty/issues/1847.

---------

Co-authored-by: David Peter <mail@david-peter.de>
2025-12-11 09:40:19 +01:00
Ibraheem Ahmed 29bf2cd201
[ty] Support implicit type of `cls` in signatures (#21771)
## Summary

Extends https://github.com/astral-sh/ruff/pull/20517 to support the
implicit type of `cls` in `@classmethod` signatures. Part of
https://github.com/astral-sh/ty/issues/159.
2025-12-10 16:56:20 -05:00
Jack O'Connor 1b44d7e2a7
[ty] add `SyntheticTypedDictType` and implement `normalized` and `is_equivalent_to` (#21784) 2025-12-10 20:36:36 +00:00
Ibraheem Ahmed a2fb2ee06c
[ty] Fix disjointness checks with type-of `@final` classes (#21770)
## 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`).
2025-12-10 15:15:10 -05:00
Douglas Creager 3e00221a6c
[ty] Fix negation upper bounds in constraint sets (#21897)
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.
2025-12-10 15:07:50 -05:00
Ibraheem Ahmed 5dc0079e78
[ty] Fix disjointness checks on `@final` class instances (#21769)
## Summary

This was left unfinished in
https://github.com/astral-sh/ruff/pull/21167. This is required to fix
our disjointness checks with type-of a final class, which is currently
broken, and blocking https://github.com/astral-sh/ty/issues/159.
2025-12-10 14:17:22 -05:00
Carl Meyer 951766d1fb
[ty] default-specialize class-literal types in assignment to generic-alias types (#21883)
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>
2025-12-10 17:18:08 +01:00
David Peter 7bf50e70a7
[ty] Generics: Respect typevar bounds when matching against a union (#21893)
## 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
2025-12-10 14:58:57 +01:00
Ibraheem Ahmed ff7086d9ad
[ty] Infer type of implicit `cls` parameter in method bodies (#21685)
## Summary

Extends https://github.com/astral-sh/ruff/pull/20922 to infer
unannotated `cls` parameters as `type[Self]` in method bodies.

Part of https://github.com/astral-sh/ty/issues/159.
2025-12-10 10:31:28 +01:00
Charlie Marsh d2aabeaaa2
[ty] Respect `kw_only` from parent class (#21820)
## Summary

Closes https://github.com/astral-sh/ty/issues/1769.

---------

Co-authored-by: Carl Meyer <carl@astral.sh>
2025-12-10 10:12:18 +01:00
Douglas Creager 4f7ad7bbc9 Merge remote-tracking branch 'origin/main' into dcreager/callable-return
* origin/main: (33 commits)
  [ty] Simplify union lower bounds and intersection upper bounds in constraint sets (#21871)
  [ty] Collapse `never` paths in constraint set BDDs (#21880)
  Fix leading comment formatting for lambdas with multiple parameters (#21879)
  [ty] Type inference for `@asynccontextmanager` (#21876)
  Fix comment placement in lambda parameters (#21868)
  [`pylint`] Detect subclasses of builtin exceptions (`PLW0133`) (#21382)
  Fix stack overflow with recursive generic protocols (depth limit) (#21858)
  New diagnostics for unused range suppressions (#21783)
  [ty] Use default settings in completion tests
  [ty] Infer type variables within generic unions  (#21862)
  [ty] Fix overload filtering to prefer more "precise" match (#21859)
  [ty] Stabilize auto-import
  [ty] Fix reveal-type E2E test (#21865)
  [ty] Use concise message for LSP clients not supporting related diagnostic information (#21850)
  Include more details in Tokens 'offset is inside token' panic message (#21860)
  apply range suppressions to filter diagnostics (#21623)
  [ty] followup: add-import action for `reveal_type` too (#21668)
  [ty] Enrich function argument auto-complete suggestions with annotated types
  [ty] Add autocomplete suggestions for function arguments
  [`flake8-bugbear`] Accept immutable slice default arguments (`B008`) (#21823)
  ...
2025-12-09 19:50:47 -05:00
David Peter a9be810c38
[ty] Type inference for `@asynccontextmanager` (#21876)
## 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
2025-12-09 22:49:00 +01:00
Carl Meyer 8727a7b179
Fix stack overflow with recursive generic protocols (depth limit) (#21858)
## Summary

This fixes https://github.com/astral-sh/ty/issues/1736 where recursive
generic protocols with growing specializations caused a stack overflow.

The issue occurred with protocols like:
```python
class C[T](Protocol):
    a: 'C[set[T]]'
```

When checking `C[set[int]]` against e.g. `C[Unknown]`, member `a`
requires checking `C[set[set[int]]]`, which requires
`C[set[set[set[int]]]]`, etc. Each level has different type
specializations, so the existing cycle detection (using full types as
cache keys) didn't catch the infinite recursion.

This fix adds a simple recursion depth limit (64) to the CycleDetector.
When the depth exceeds the limit, we return the fallback value (assume
compatible) to safely terminate the recursion.

This is a bit of a blunt hammer, but it should be broadly effective to
prevent stack overflow in any nested-relation case, and it's hard to
imagine that non-recursive nested relation comparisons of depth > 64
exist much in the wild.

## Test Plan

Added mdtest.
2025-12-09 09:05:18 -08:00
David Peter aea2bc2308
[ty] Infer type variables within generic unions (#21862)
## Summary

This PR allows our generics solver to find a solution for `T` in cases
like the following:
```py
def extract_t[T](x: P[T] | Q[T]) -> T:
    raise NotImplementedError

reveal_type(extract_t(P[int]()))  # revealed: int
reveal_type(extract_t(Q[str]()))  # revealed: str
```

closes https://github.com/astral-sh/ty/issues/1772
closes https://github.com/astral-sh/ty/issues/1314

## Ecosystem

The impact here looks very good!

It took me a long time to figure this out, but the new diagnostics on
bokeh are actually true positives. I should have tested with another
type-checker immediately, I guess. All other type checkers also emit
errors on these `__init__` calls. MRE
[here](https://play.ty.dev/5c19d260-65e2-4f70-a75e-1a25780843a2) (no
error on main, diagnostic on this branch)

A lot of false positives on home-assistant go away for calls to
functions like
[`async_listen`](180053fe98/homeassistant/core.py (L1581-L1587))
which take a `event_type: EventType[_DataT] | str` parameter. We can now
solve for `_DataT` here, which was previously falling back to its
default value, and then caused problems because it was used as an
argument to an invariant generic class.

## Test Plan

New Markdown tests
2025-12-09 16:22:59 +01:00
Dhruv Manilawala c35bf8f441
[ty] Fix overload filtering to prefer more "precise" match (#21859)
## Summary

fixes: https://github.com/astral-sh/ty/issues/1809

I took this chance to add some debug level tracing logs for overload
call evaluation similar to Doug's implementation in `constraints.rs`.

## Test Plan

- Add new mdtests
- Tested it against `sqlalchemy.select` in pyx which results in the
correct overload being matched
2025-12-09 20:29:34 +05:30