Commit Graph

746 Commits

Author SHA1 Message Date
Douglas Creager 1e33d25d1c fix test 2025-12-03 16:38:01 -05:00
Douglas Creager 3bcca62472 doc 2025-12-03 12:12:00 -05:00
Douglas Creager 85e6143e07 use self annotation in synthesized __init__ callable 2025-12-03 12:09:04 -05:00
Douglas Creager 77ce24a5bf allow multiple overloads/callables when inferring 2025-12-03 12:04:59 -05:00
Douglas Creager db5834dfd7 add failing tests 2025-12-03 12:04:00 -05:00
Douglas Creager 2e46c8de06 Merge remote-tracking branch 'origin/main' into dcreager/callable-return
* origin/main:
  [ty] Reachability constraints: minor documentation fixes (#21774)
  [ty] Fix non-determinism in `ConstraintSet.specialize_constrained` (#21744)
  [ty] Improve `@override`, `@final` and Liskov checks in cases where there are multiple reachable definitions (#21767)
  [ty] Extend `invalid-explicit-override` to also cover properties decorated with `@override` that do not override anything (#21756)
  [ty] Enable LRU collection for parsed module (#21749)
  [ty] Support typevar-specialized dynamic types in generic type aliases (#21730)
  Add token based `parenthesized_ranges` implementation (#21738)
  [ty] Default-specialization of generic type aliases (#21765)
  [ty] Suppress false positives when `dataclasses.dataclass(...)(cls)` is called imperatively (#21729)
  [syntax-error] Default type parameter followed by non-default type parameter (#21657)
2025-12-03 10:48:36 -05:00
David Peter d6e472f297
[ty] Reachability constraints: minor documentation fixes (#21774) 2025-12-03 16:40:11 +01:00
Douglas Creager 45842cc034
[ty] Fix non-determinism in `ConstraintSet.specialize_constrained` (#21744)
This fixes a non-determinism that we were seeing in the constraint set
tests in https://github.com/astral-sh/ruff/pull/21715.

In this test, we create the following constraint set, and then try to
create a specialization from it:

```
(T@constrained_by_gradual_list = list[Base])
  ∨
(Bottom[list[Any]] ≤ T@constrained_by_gradual_list ≤ Top[list[Any]])
```

That is, `T` is either specifically `list[Base]`, or it's any `list`.
Our current heuristics say that, absent other restrictions, we should
specialize `T` to the more specific type (`list[Base]`).

In the correct test output, we end up creating a BDD that looks like
this:

```
(T@constrained_by_gradual_list = list[Base])
┡━₁ always
└─₀ (Bottom[list[Any]] ≤ T@constrained_by_gradual_list ≤ Top[list[Any]])
    ┡━₁ always
    └─₀ never
```

In the incorrect output, the BDD looks like this:

```
(Bottom[list[Any]] ≤ T@constrained_by_gradual_list ≤ Top[list[Any]])
┡━₁ always
└─₀ never
```

The difference is the ordering of the two individual constraints. Both
constraints appear in the first BDD, but the second BDD only contains `T
is any list`. If we were to force the second BDD to contain both
constraints, it would look like this:

```
(Bottom[list[Any]] ≤ T@constrained_by_gradual_list ≤ Top[list[Any]])
┡━₁ always
└─₀ (T@constrained_by_gradual_list = list[Base])
    ┡━₁ always
    └─₀ never
```

This is the standard shape for an OR of two constraints. However! Those
two constraints are not independent of each other! If `T` is
specifically `list[Base]`, then it's definitely also "any `list`". From
that, we can infer the contrapositive: that if `T` is not any list, then
it cannot be `list[Base]` specifically. When we encounter impossible
situations like that, we prune that path in the BDD, and treat it as
`false`. That rewrites the second BDD to the following:

```
(Bottom[list[Any]] ≤ T@constrained_by_gradual_list ≤ Top[list[Any]])
┡━₁ always
└─₀ (T@constrained_by_gradual_list = list[Base])
    ┡━₁ never   <-- IMPOSSIBLE, rewritten to never
    └─₀ never
```

We then would see that that BDD node is redundant, since both of its
outgoing edges point at the `never` node. Our BDDs are _reduced_, which
means we have to remove that redundant node, resulting in the BDD we saw
above:

```
(Bottom[list[Any]] ≤ T@constrained_by_gradual_list ≤ Top[list[Any]])
┡━₁ always
└─₀ never       <-- redundant node removed
```

The end result is that we were "forgetting" about the `T = list[Base]`
constraint, but only for some BDD variable orderings.

To fix this, I'm leaning in to the fact that our BDDs really do need to
"remember" all of the constraints that they were created with. Some
combinations might not be possible, but we now have the sequent map,
which is quite good at detecting and pruning those.

So now our BDDs are _quasi-reduced_, which just means that redundant
nodes are allowed. (At first I was worried that allowing redundant nodes
would be an unsound "fix the glitch". But it turns out they're real!
[This](https://ieeexplore.ieee.org/abstract/document/130209) is the
paper that introduces them, though it's very difficult to read. Knuth
mentions them in §7.1.4 of
[TAOCP](https://course.khoury.northeastern.edu/csu690/ssl/bdd-knuth.pdf),
and [this paper](https://par.nsf.gov/servlets/purl/10128966) has a nice
short summary of them in §2.)

While we're here, I've added a bunch of `debug` and `trace` level log
messages to the constraint set implementation. I was getting tired of
having to add these by hands over and over. To enable them, just set
`TY_LOG` in your environment, e.g.

```sh
env TY_LOG=ty_python_semantic::types::constraints::SequentMap=trace ty check ...
```

[Note, this has an `internal` label because are still not using
`specialize_constrained` in anything user-facing yet.]
2025-12-03 10:19:39 -05:00
Alex Waygood cd079bd92e
[ty] Improve `@override`, `@final` and Liskov checks in cases where there are multiple reachable definitions (#21767) 2025-12-03 12:51:36 +00:00
Alex Waygood 5756b3809c
[ty] Extend `invalid-explicit-override` to also cover properties decorated with `@override` that do not override anything (#21756) 2025-12-03 11:27:47 +00:00
David Peter 21e5a57296
[ty] Support typevar-specialized dynamic types in generic type aliases (#21730)
## Summary

For a type alias like the one below, where `UnknownClass` is something
with a dynamic type, we previously lost track of the fact that this
dynamic type was explicitly specialized *with a type variable*. If that
alias is then later explicitly specialized itself (`MyAlias[int]`), we
would miscount the number of legacy type variables and emit a
`invalid-type-arguments` diagnostic
([playground](https://play.ty.dev/886ae6cc-86c3-4304-a365-510d29211f85)).
```py
T = TypeVar("T")

MyAlias: TypeAlias = UnknownClass[T] | None
```
The solution implemented here is not pretty, but we can hopefully get
rid of it via https://github.com/astral-sh/ty/issues/1711. Also, once we
properly support `ParamSpec` and `Concatenate`, we should be able to
remove some of this code.

This addresses many of the `invalid-type-arguments` false-positives in
https://github.com/astral-sh/ty/issues/1685. With this change, there are
still some diagnostics of this type left. Instead of implementing even
more (rather sophisticated) workarounds for these cases as well, it
might be much easier to wait for full `ParamSpec`/`Concatenate` support
and then try again.

A disadvantage of this implementation is that we lose track of some
`@Todo` types and replace them with `Unknown`. We could spend more
effort and try to preserve them, but I'm unsure if this is the best use
of our time right now.

## Test Plan

New Markdown tests.
2025-12-03 10:00:02 +01:00
David Peter e6ddeed386
[ty] Default-specialization of generic type aliases (#21765)
## Summary

Implement default-specialization of generic type aliases (implicit or
PEP-613) if they are used in a type expression without an explicit
specialization.

closes https://github.com/astral-sh/ty/issues/1690

## Typing conformance

```diff
-generics_defaults_specialization.py:26:5: error[type-assertion-failure] Type `SomethingWithNoDefaults[int, str]` does not match asserted type `SomethingWithNoDefaults[int, DefaultStrT]`
```

That's exactly what we want ✔️ 

All other tests in this file pass as well, with the exception of this
assertion, which is just wrong (at least according to our
interpretation, `type[Bar] != <class 'Bar'>`). I checked that we do
correctly default-specialize the type parameter which is not displayed
in the diagnostic that we raise.
```py
class Bar(SubclassMe[int, DefaultStrT]): ...

assert_type(Bar, type[Bar[str]])  # ty: Type `type[Bar[str]]` does not match asserted type `<class 'Bar'>`
```

## Ecosystem impact

Looks like I should have included this last week 😎 

## Test Plan

Updated pre-existing tests and add a few new ones.
2025-12-03 09:10:45 +01:00
Alex Waygood c5b8d551df
[ty] Suppress false positives when `dataclasses.dataclass(...)(cls)` is called imperatively (#21729)
Fixes https://github.com/astral-sh/ty/issues/1705
2025-12-03 08:05:25 +00:00
Douglas Creager d3fd988337 fix tests 2025-12-02 21:49:03 -05:00
Douglas Creager a0f64bd0ae even more hack 2025-12-02 21:41:55 -05:00
Douglas Creager beb2956a14 carry over failing test from conformance suite 2025-12-02 21:32:02 -05:00
Douglas Creager a303b7a8aa Merge remote-tracking branch 'origin/main' into dcreager/callable-return
* origin/main:
  new module for parsing ranged suppressions (#21441)
  [ty] `type[T]` is assignable to an inferable typevar (#21766)
  Fix syntax error false positives for `await` outside functions (#21763)
  [ty] Improve diagnostics for unsupported comparison operations (#21737)
2025-12-02 18:42:43 -05:00
Ibraheem Ahmed 7b0aab1696
[ty] `type[T]` is assignable to an inferable typevar (#21766)
## Summary

Resolves https://github.com/astral-sh/ty/issues/1712.
2025-12-02 18:25:09 -05:00
Douglas Creager 7bbf839325 hackity hack 2025-12-02 18:24:15 -05:00
Brent Westbrook 2250fa6f98
Fix syntax error false positives for `await` outside functions (#21763)
## Summary

Fixes #21750 and a related bug in `PLE1142`. We were not properly
considering generators to be valid `await` contexts, which caused the
`F704` issue. One of the tests I added for this also uncovered an issue
in `PLE1142` for comprehensions nested within async generators because
we were only checking the current scope rather than traversing the
nested context.

## Test Plan

Both of these rules are implemented as semantic syntax errors, so I
added tests (and fixes) in both Ruff and ty.
2025-12-02 21:02:02 +00:00
Douglas Creager 957304ec15 mdlint 2025-12-02 15:40:43 -05:00
Alex Waygood 392a8e4e50
[ty] Improve diagnostics for unsupported comparison operations (#21737) 2025-12-02 19:58:45 +00:00
Douglas Creager d88120b187 mark these as TODO 2025-12-02 14:46:29 -05:00
Douglas Creager 2b949b3e67 Merge remote-tracking branch 'origin/main' into dcreager/callable-return
* origin/main: (67 commits)
  Move `Token`, `TokenKind` and `Tokens` to `ruff-python-ast` (#21760)
  [ty] Don't confuse multiple occurrences of `typing.Self` when binding bound methods (#21754)
  Use our org-wide Renovate preset (#21759)
  Delete `my-script.py` (#21751)
  [ty] Move `all_members`, and related types/routines, out of `ide_support.rs` (#21695)
  [ty] Fix find-references for import aliases (#21736)
  [ty] add tests for workspaces (#21741)
  [ty] Stop testing the (brittle) constraint set display implementation (#21743)
  [ty] Use generator over list comprehension to avoid cast (#21748)
  [ty] Add a diagnostic for prohibited `NamedTuple` attribute overrides (#21717)
  [ty] Fix subtyping with `type[T]` and unions (#21740)
  Use `npm ci --ignore-scripts` everywhere (#21742)
  [`flake8-simplify`] Fix truthiness assumption for non-iterable arguments in tuple/list/set calls (`SIM222`, `SIM223`) (#21479)
  [`flake8-use-pathlib`] Mark fixes unsafe for return type changes (`PTH104`, `PTH105`, `PTH109`, `PTH115`) (#21440)
  [ty] Fix auto-import code action to handle pre-existing import
  Enable PEP 740 attestations when publishing to PyPI (#21735)
  [ty] Fix find references for type defined in stub (#21732)
  Use OIDC instead of codspeed token (#21719)
  [ty] Exclude `typing_extensions` from completions unless it's really available
  [ty] Fix false positives for `class F(Generic[*Ts]): ...` (#21723)
  ...
2025-12-02 14:23:15 -05:00
Douglas Creager 508c0a0861
[ty] Don't confuse multiple occurrences of `typing.Self` when binding bound methods (#21754)
In the following example, there are two occurrences of `typing.Self`,
one for `Foo.foo` and one for `Bar.bar`:

```py
from typing import Self, reveal_type

class Foo[T]:
    def foo(self: Self) -> T:
        raise NotImplementedError

class Bar:
    def bar(self: Self, x: Foo[Self]):
        # SHOULD BE: bound method Foo[Self@bar].foo() -> Self@bar
        # revealed: bound method Foo[Self@bar].foo() -> Foo[Self@bar]
        reveal_type(x.foo)

def f[U: Bar](x: Foo[U]):
    # revealed: bound method Foo[U@f].foo() -> U@f
    reveal_type(x.foo)
```

When accessing a bound method, we replace any occurrences of `Self` with
the bound `self` type.

We were doing this correctly for the second reveal. We would first apply
the specialization, getting `(self: Self@foo) -> U@F` as the signature
of `x.foo`. We would then bind the `self` parameter, substituting
`Self@foo` with `Foo[U@F]` as part of that. The return type was already
specialized to `U@F`, so that substitution had no further affect on the
type that we revealed.

In the first reveal, we would follow the same process, but we confused
the two occurrences of `Self`. We would first apply the specialization,
getting `(self: Self@foo) -> Self@bar` as the method signature. We would
then try to bind the `self` parameter, substituting `Self@foo` with
`Foo[Self@bar]`. However, because we didn't distinguish the two separate
`Self`s, and applied the substitution to the return type as well as to
the `self` parameter.

The fix is to track which particular `Self` we're trying to substitute
when applying the type mapping.

Fixes https://github.com/astral-sh/ty/issues/1713
2025-12-02 13:15:09 -05:00
Aria Desires 015ab9e576
[ty] add tests for workspaces (#21741)
Here are a bunch of (variously failing and passing) mdtests that reflect
the kinds of issues people encounter when running ty over an entire
workspace without sufficient hand-holding (especially because in the IDE
it is unclear *how* to provide that hand-holding).
2025-12-02 06:43:41 -05:00
Douglas Creager cf4196466c
[ty] Stop testing the (brittle) constraint set display implementation (#21743)
The `Display` implementation for constraint sets is brittle, and
deserves a rethink. But later! It's perfectly fine for printf debugging;
we just shouldn't be writing mdtests that depend on any particular
rendering details. Most of these tests can be replaced with an
equivalence check that actually validates that the _behavior_ of two
constraint sets are identical.
2025-12-02 09:17:29 +01:00
Charlie Marsh 72304b01eb
[ty] Add a diagnostic for prohibited `NamedTuple` attribute overrides (#21717)
## Summary

Closes https://github.com/astral-sh/ty/issues/1684.
2025-12-01 21:46:58 -05:00
Ibraheem Ahmed ec854c7199
[ty] Fix subtyping with `type[T]` and unions (#21740)
## Summary

Resolves
https://github.com/astral-sh/ruff/pull/21685#issuecomment-3591695954.
2025-12-01 18:20:13 -05:00
Alex Waygood 0e651b50b7
[ty] Fix false positives for `class F(Generic[*Ts]): ...` (#21723) 2025-12-01 13:24:07 +00:00
David Peter 116fd7c7af
[ty] Remove `GenericAlias`-related todo type (#21728)
## Summary

If you manage to create an `typing.GenericAlias` instance without us
knowing how that was created, then we don't know what to do with this in
a type annotation. So it's better to be explicit and show an error
instead of failing silently with a `@Todo` type.

## Test Plan

* New Markdown tests
* Zero ecosystem impact
2025-12-01 13:02:38 +00:00
David Peter 5358ddae88
[ty] Exhaustiveness checking for generic classes (#21726)
## Summary

We had tests for this already, but they used generic classes that were
bivariant in their type parameter, and so this case wasn't captured.

closes https://github.com/astral-sh/ty/issues/1702

## Test Plan

Updated Markdown tests
2025-12-01 13:52:36 +01:00
Alex Waygood 3a11e714c6
[ty] Show the user where the type variable was defined in `invalid-type-arguments` diagnostics (#21727) 2025-12-01 12:25:49 +00:00
Alex Waygood a2096ee2cb
[ty] Emit `invalid-named-tuple` on namedtuple classes that have field names starting with underscores (#21697) 2025-12-01 11:36:02 +00:00
Carl Meyer c2773b4c6f
[ty] support `type[tuple[...]]` (#21652)
Fixes https://github.com/astral-sh/ty/issues/1649

## Summary

We missed this when adding support for `type[]` of a specialized
generic.

## Test Plan

Added mdtests.
2025-12-01 11:49:26 +01:00
David Peter bc6517a807
[ty] Add missing projects to `good.txt` (#21721)
## Summary

These projects from `mypy_primer` were missing from both `good.txt` and
`bad.txt` for some reason. I thought about writing a script that would
verify that `good.txt` + `bad.txt` = `mypy_primer.projects`, but that's
not completely trivial since there are projects like `cpython` only
appear once in `good.txt`. Given that we can hopefully soon get rid of
both of these files (and always run on all projects), it's probably not
worth the effort. We are usually notified of all `mypy_primer` changes.

## Test Plan

CI on this PR
2025-12-01 11:18:41 +01:00
Shunsuke Shibayama a6cbc138d2
[ty] remove the `visitor` parameter in the `recursive_type_normalized_impl` method (#21701) 2025-12-01 08:48:43 +01:00
Charlie Marsh e7beb7e1f4
[ty] Forbid use of `super()` in `NamedTuple` subclasses (#21700)
## Summary

The exact behavior around what's allowed vs. disallowed was partly
detected through trial and error in the runtime.

I was a little confused by [this
comment](https://github.com/python/cpython/pull/129352) that says
"`NamedTuple` subclasses cannot be inherited from" because in practice
that doesn't appear to error at runtime.

Closes [#1683](https://github.com/astral-sh/ty/issues/1683).
2025-11-30 15:49:06 +00:00
Alex Waygood b02e8212c9
[ty] Don't introduce invalid syntax when autofixing override-of-final-method (#21699) 2025-11-30 13:40:33 +00:00
Micha Reiser d40590c8f9
[ty] Add code action to ignore diagnostic on the current line (#21595) 2025-11-29 15:41:54 +01:00
Dhruv Manilawala 8795d9f0cb
[ty] Split `ParamSpec` mdtests to separate legacy and PEP 695 tests (#21687)
## Summary

This is another small refactor for
https://github.com/astral-sh/ruff/pull/21445 that splits the single
`paramspec.md` into `generics/legacy/paramspec.md` and
`generics/pep695/paramspec.md`.

## Test Plan

Make sure that all mdtests pass.
2025-11-29 06:49:39 +00:00
David Peter 42f152108a
[ty] Generic types aliases (implicit and PEP 613) (#21553)
## Summary

Add support for generic PEP 613 type aliases and generic implicit type
aliases:
```py
from typing import TypeVar

T = TypeVar("T")
ListOrSet = list[T] | set[T]

def _(xs: ListOrSet[int]):
    reveal_type(xs)  # list[int] | set[int]
```

closes https://github.com/astral-sh/ty/issues/1643
closes https://github.com/astral-sh/ty/issues/1629
closes https://github.com/astral-sh/ty/issues/1596
closes https://github.com/astral-sh/ty/issues/573
closes https://github.com/astral-sh/ty/issues/221

## Typing conformance

```diff
-aliases_explicit.py:52:5: error[type-assertion-failure] Type `list[int]` does not match asserted type `@Todo(specialized generic alias in type expression)`
-aliases_explicit.py:53:5: error[type-assertion-failure] Type `tuple[str, ...] | list[str]` does not match asserted type `@Todo(Generic specialization of types.UnionType)`
-aliases_explicit.py:54:5: error[type-assertion-failure] Type `tuple[int, int, int, str]` does not match asserted type `@Todo(specialized generic alias in type expression)`
-aliases_explicit.py:56:5: error[type-assertion-failure] Type `(int, str, /) -> str` does not match asserted type `@Todo(Generic specialization of typing.Callable)`
-aliases_explicit.py:59:5: error[type-assertion-failure] Type `int | str | None | list[list[int]]` does not match asserted type `int | str | None | list[@Todo(specialized generic alias in type expression)]`
```

New true negatives ✔️ 

```diff
+aliases_explicit.py:41:36: error[invalid-type-arguments] Too many type arguments: expected 1, got 2
-aliases_explicit.py:57:5: error[type-assertion-failure] Type `(int, str, str, /) -> None` does not match asserted type `@Todo(Generic specialization of typing.Callable)`
+aliases_explicit.py:57:5: error[type-assertion-failure] Type `(int, str, str, /) -> None` does not match asserted type `(...) -> Unknown`
```

These require `ParamSpec`

```diff
+aliases_explicit.py:67:24: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
+aliases_explicit.py:68:24: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
+aliases_explicit.py:69:29: error[invalid-type-arguments] Too many type arguments: expected 1, got 2
+aliases_explicit.py:70:29: error[invalid-type-arguments] Too many type arguments: expected 1, got 2
+aliases_explicit.py:71:29: error[invalid-type-arguments] Too many type arguments: expected 1, got 2
+aliases_explicit.py:102:20: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
```

New true positives ✔️ 

```diff
-aliases_implicit.py:63:5: error[type-assertion-failure] Type `list[int]` does not match asserted type `@Todo(specialized generic alias in type expression)`
-aliases_implicit.py:64:5: error[type-assertion-failure] Type `tuple[str, ...] | list[str]` does not match asserted type `@Todo(Generic specialization of types.UnionType)`
-aliases_implicit.py:65:5: error[type-assertion-failure] Type `tuple[int, int, int, str]` does not match asserted type `@Todo(specialized generic alias in type expression)`
-aliases_implicit.py:67:5: error[type-assertion-failure] Type `(int, str, /) -> str` does not match asserted type `@Todo(Generic specialization of typing.Callable)`
-aliases_implicit.py:70:5: error[type-assertion-failure] Type `int | str | None | list[list[int]]` does not match asserted type `int | str | None | list[@Todo(specialized generic alias in type expression)]`
-aliases_implicit.py:71:5: error[type-assertion-failure] Type `list[bool]` does not match asserted type `@Todo(specialized generic alias in type expression)`
```

New true negatives ✔️ 

```diff
+aliases_implicit.py:54:36: error[invalid-type-arguments] Too many type arguments: expected 1, got 2
-aliases_implicit.py:68:5: error[type-assertion-failure] Type `(int, str, str, /) -> None` does not match asserted type `@Todo(Generic specialization of typing.Callable)`
+aliases_implicit.py:68:5: error[type-assertion-failure] Type `(int, str, str, /) -> None` does not match asserted type `(...) -> Unknown`
```

These require `ParamSpec`

```diff
+aliases_implicit.py:76:24: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
+aliases_implicit.py:77:24: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
+aliases_implicit.py:78:29: error[invalid-type-arguments] Too many type arguments: expected 1, got 2
+aliases_implicit.py:79:29: error[invalid-type-arguments] Too many type arguments: expected 1, got 2
+aliases_implicit.py:80:29: error[invalid-type-arguments] Too many type arguments: expected 1, got 2
+aliases_implicit.py:81:25: error[invalid-type-arguments] Type `str` is not assignable to upper bound `int | float` of type variable `TFloat@GoodTypeAlias12`
+aliases_implicit.py:135:20: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
```

New true positives ✔️ 

```diff
+callables_annotation.py:172:19: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
+callables_annotation.py:175:19: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
+callables_annotation.py:188:25: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
+callables_annotation.py:189:25: error[invalid-type-arguments] Too many type arguments: expected 0, got 1
```

These require `ParamSpec` and `Concatenate`.

```diff
-generics_defaults_specialization.py:26:5: error[type-assertion-failure] Type `SomethingWithNoDefaults[int, str]` does not match asserted type `SomethingWithNoDefaults[int, typing.TypeVar]`
+generics_defaults_specialization.py:26:5: error[type-assertion-failure] Type `SomethingWithNoDefaults[int, str]` does not match asserted type `SomethingWithNoDefaults[int, DefaultStrT]`
```

Favorable diagnostic change ✔️ 

```diff
-generics_defaults_specialization.py:27:5: error[type-assertion-failure] Type `SomethingWithNoDefaults[int, bool]` does not match asserted type `@Todo(specialized generic alias in type expression)`
```

New true negative ✔️ 

```diff
-generics_defaults_specialization.py:30:1: error[non-subscriptable] Cannot subscript object of type `<class 'SomethingWithNoDefaults[int, typing.TypeVar]'>` with no `__class_getitem__` method
+generics_defaults_specialization.py:30:15: error[invalid-type-arguments] Too many type arguments: expected between 0 and 1, got 2
```

Correct new diagnostic ✔️ 


```diff
-generics_variance.py:175:25: error[non-subscriptable] Cannot subscript object of type `<class 'Contra[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:175:35: error[non-subscriptable] Cannot subscript object of type `<class 'Co[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:179:29: error[non-subscriptable] Cannot subscript object of type `<class 'Contra[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:179:39: error[non-subscriptable] Cannot subscript object of type `<class 'Contra[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:183:21: error[non-subscriptable] Cannot subscript object of type `<class 'Co[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:183:27: error[non-subscriptable] Cannot subscript object of type `<class 'Co[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:187:25: error[non-subscriptable] Cannot subscript object of type `<class 'Co[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:187:31: error[non-subscriptable] Cannot subscript object of type `<class 'Contra[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:191:33: error[non-subscriptable] Cannot subscript object of type `<class 'Contra[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:191:43: error[non-subscriptable] Cannot subscript object of type `<class 'Co[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:191:49: error[non-subscriptable] Cannot subscript object of type `<class 'Contra[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:196:5: error[non-subscriptable] Cannot subscript object of type `<class 'Contra[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:196:15: error[non-subscriptable] Cannot subscript object of type `<class 'Contra[typing.TypeVar]'>` with no `__class_getitem__` method
-generics_variance.py:196:25: error[non-subscriptable] Cannot subscript object of type `<class 'Contra[typing.TypeVar]'>` with no `__class_getitem__` method
```

One of these should apparently be an error, but not of this kind, so
this is good ✔️

```diff
-specialtypes_type.py:152:16: error[invalid-type-form] `typing.TypeVar` is not a generic class
-specialtypes_type.py:156:16: error[invalid-type-form] `typing.TypeVar` is not a generic class
```

Good, those were false positives. ✔️ 

I skipped the analysis for everything involving `TypeVarTuple`.

## Ecosystem impact

**[Full report with detailed
diff](https://david-generic-implicit-alias.ecosystem-663.pages.dev/diff)**

Previous iterations of this PR showed all kinds of problems. In it's
current state, I do not see any large systematic problems, but it is
hard to tell with 5k diagnostic changes.

## Performance

* There is a huge 4x regression in `colour-science/colour`, related to
[this large
file](https://github.com/colour-science/colour/blob/develop/colour/io/luts/tests/test_lut.py)
with [many assignments of hard-coded arrays (lists of lists) to
`np.NDArray`
types](83e754c8b6/colour/io/luts/tests/test_lut.py (L701-L781))
that we now understand. We now take ~2 seconds to check this file, so
definitely not great, but maybe acceptable for now.

## Test Plan

Updated and new Markdown tests
2025-11-28 20:38:24 +01:00
Alex Waygood 594b7b04d3
[ty] Preserve quoting style when autofixing `TypedDict` keys (#21682) 2025-11-28 18:40:34 +00:00
David Peter 0084e94f78
[ty] Fix subtyping of `type[Any]` / `type[T]` and protocols (#21678)
## Summary

This is a bugfix for subtyping of `type[Any]` / `type[T]` and protocols.

## Test Plan

Regression test that will only be really meaningful once
https://github.com/astral-sh/ruff/pull/21553 lands.
2025-11-28 16:56:22 +01:00
Alex Waygood 8bcfc198b8
[ty] Implement `typing.final` for methods (#21646)
Co-authored-by: Micha Reiser <micha@reiser.io>
2025-11-28 15:18:02 +00:00
Ibraheem Ahmed 3ed537e9f1
[ty] Support `type[T]` with type variables (#21650)
## Summary

Adds support for `type[T]`, where `T` is a type variable.

- Resolves https://github.com/astral-sh/ty/issues/501
- Resolves https://github.com/astral-sh/ty/issues/783
- Resolves https://github.com/astral-sh/ty/issues/662
2025-11-28 09:20:24 +01:00
Alex Waygood 53efc82989
[ty] Include all members on `type` in autocompletion suggestions for `type[]` types (#21670) 2025-11-27 19:29:25 +00:00
Alex Waygood aef2fad0c5
[ty] Add IDE autofixes for two "Did you mean...?" suggestions (#21667) 2025-11-27 18:20:02 +00:00
Alex Waygood a7d48ffd40
[ty] Add subdiagnostic hint if a variable with type `Never` is used in a type expression (#21660) 2025-11-27 12:48:18 +00:00
Carl Meyer 77f8fa6906
[ty] more precise inference for a failed specialization (#21651)
## Summary

Previously if an explicit specialization failed (e.g. wrong number of
type arguments or violates an upper bound) we just inferred `Unknown`
for the entire type. This actually caused us to panic on an a case of a
recursive upper bound with invalid specialization; the upper bound would
oscillate indefinitely in fixpoint iteration between `Unknown` and the
given specialization. This could be fixed with a cycle recovery
function, but in this case there's a simpler fix: if we infer
`C[Unknown]` instead of `Unknown` for an invalid attempt to specialize
`C`, that allows fixpoint iteration to quickly converge, as well as
giving a more precise type inference.

Other type checkers actually just go with the attempted specialization
even if it's invalid. So if `C` has a type parameter with upper bound
`int`, and you say `C[str]`, they'll emit a diagnostic but just go with
`C[str]`. Even weirder, if `C` has a single type parameter and you say
`C[str, bytes]`, they'll just go with `C[str]` as the type. I'm not
convinced by this approach; it seems odd to have specializations
floating around that explicitly violate the declared upper bound, or in
the latter case aren't even the specialization the annotation requested.
I prefer `C[Unknown]` for this case.

Fixing this revealed an issue with `collections.namedtuple`, which
returns `type[tuple[Any, ...]]`. Due to
https://github.com/astral-sh/ty/issues/1649 we consider that to be an
invalid specialization. So previously we returned `Unknown`; after this
PR it would be `type[tuple[Unknown]]`, leading to more false positives
from our lack of functional namedtuple support. To avoid that I added an
explicit Todo type for functional namedtuples for now.

## Test Plan

Added and updated mdtests.

The conformance suite changes have to do with `ParamSpec`, so no
meaningful signal there.

The ecosystem changes appear to be the expected effects of having more
precise type information (including occurrences of known issues such as
https://github.com/astral-sh/ty/issues/1495 ). Most effects are just
changes to types in diagnostics.
2025-11-27 13:44:28 +01:00