## Summary
As-is, a single-element tuple gets destructured via:
```rust
let arguments = if let ast::Expr::Tuple(tuple) = slice {
&*tuple.elts
} else {
std::slice::from_ref(slice)
};
```
But then, because it's a single element, we call
`infer_annotation_expression_impl`, passing in the tuple, rather than
the first element.
Closes https://github.com/astral-sh/ty/issues/1793.
Closes https://github.com/astral-sh/ty/issues/1768.
---------
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>
## Summary
Closes: https://github.com/astral-sh/ty/issues/157
This PR adds support for the following capabilities involving a
`ParamSpec` type variable:
- Representing `P.args` and `P.kwargs` in the type system
- Matching against a callable containing `P` to create a type mapping
- Specializing `P` against the stored parameters
The value of a `ParamSpec` type variable is being represented using
`CallableType` with a `CallableTypeKind::ParamSpecValue` variant. This
`CallableTypeKind` is expanded from the existing `is_function_like`
boolean flag. An `enum` is used as these variants are mutually
exclusive.
For context, an initial iteration made an attempt to expand the
`Specialization` to use `TypeOrParameters` enum that represents that a
type variable can specialize into either a `Type` or `Parameters` but
that increased the complexity of the code as all downstream usages would
need to handle both the variants appropriately. Additionally, we'd have
also need to establish an invariant that a regular type variable always
maps to a `Type` while a paramspec type variable always maps to a
`Parameters`.
I've intentionally left out checking and raising diagnostics when the
`ParamSpec` type variable and it's components are not being used
correctly to avoid scope increase and it can easily be done as a
follow-up. This would also include the scoping rules which I don't think
a regular type variable implements either.
## Test Plan
Add new mdtest cases and update existing test cases.
Ran this branch on pyx, no new diagnostics.
### Ecosystem analysis
There's a case where in an annotated assignment like:
```py
type CustomType[P] = Callable[...]
def value[**P](...): ...
def another[**P](...):
target: CustomType[P] = value
```
The type of `value` is a callable and it has a paramspec that's bound to
`value`, `CustomType` is a type alias that's a callable and `P` that's
used in it's specialization is bound to `another`. Now, ty infers the
type of `target` same as `value` and does not use the declared type
`CustomType[P]`. [This is the
assignment](0980b9d9ab/src/async_utils/gen_transform.py (L108))
that I'm referring to which then leads to error in downstream usage.
Pyright and mypy does seem to use the declared type.
There are multiple diagnostics in `dd-trace-py` that requires support
for `cls`.
I'm seeing `Divergent` type for an example like which ~~I'm not sure
why, I'll look into it tomorrow~~ is because of a cycle as mentioned in
https://github.com/astral-sh/ty/issues/1729#issuecomment-3612279974:
```py
from typing import Callable
def decorator[**P](c: Callable[P, int]) -> Callable[P, str]: ...
@decorator
def func(a: int) -> int: ...
# ((a: int) -> str) | ((a: Divergent) -> str)
reveal_type(func)
```
I ~~need to look into why are the parameters not being specialized
through multiple decorators in the following code~~ think this is also
because of the cycle mentioned in
https://github.com/astral-sh/ty/issues/1729#issuecomment-3612279974 and
the fact that we don't support `staticmethod` properly:
```py
from contextlib import contextmanager
class Foo:
@staticmethod
@contextmanager
def method(x: int):
yield
foo = Foo()
# ty: Revealed type: `() -> _GeneratorContextManager[Unknown, None, None]` [revealed-type]
reveal_type(foo.method)
```
There's some issue related to `Protocol` that are generic over a
`ParamSpec` in `starlette` which might be related to
https://github.com/astral-sh/ty/issues/1635 but I'm not sure. Here's a
minimal example to reproduce:
<details><summary>Code snippet:</summary>
<p>
```py
from collections.abc import Awaitable, Callable, MutableMapping
from typing import Any, Callable, ParamSpec, Protocol
P = ParamSpec("P")
Scope = MutableMapping[str, Any]
Message = MutableMapping[str, Any]
Receive = Callable[[], Awaitable[Message]]
Send = Callable[[Message], Awaitable[None]]
ASGIApp = Callable[[Scope, Receive, Send], Awaitable[None]]
_Scope = Any
_Receive = Callable[[], Awaitable[Any]]
_Send = Callable[[Any], Awaitable[None]]
# Since `starlette.types.ASGIApp` type differs from `ASGIApplication` from `asgiref`
# we need to define a more permissive version of ASGIApp that doesn't cause type errors.
_ASGIApp = Callable[[_Scope, _Receive, _Send], Awaitable[None]]
class _MiddlewareFactory(Protocol[P]):
def __call__(
self, app: _ASGIApp, *args: P.args, **kwargs: P.kwargs
) -> _ASGIApp: ...
class Middleware:
def __init__(
self, factory: _MiddlewareFactory[P], *args: P.args, **kwargs: P.kwargs
) -> None:
self.factory = factory
self.args = args
self.kwargs = kwargs
class ServerErrorMiddleware:
def __init__(
self,
app: ASGIApp,
value: int | None = None,
flag: bool = False,
) -> None:
self.app = app
self.value = value
self.flag = flag
async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None: ...
# ty: Argument to bound method `__init__` is incorrect: Expected `_MiddlewareFactory[(...)]`, found `<class 'ServerErrorMiddleware'>` [invalid-argument-type]
Middleware(ServerErrorMiddleware, value=500, flag=True)
```
</p>
</details>
### Conformance analysis
> ```diff
> -constructors_callable.py:36:13: info[revealed-type] Revealed type:
`(...) -> Unknown`
> +constructors_callable.py:36:13: info[revealed-type] Revealed type:
`(x: int) -> Unknown`
> ```
Requires return type inference i.e.,
https://github.com/astral-sh/ruff/pull/21551
> ```diff
> +constructors_callable.py:194:16: error[invalid-argument-type]
Argument is incorrect: Expected `list[T@__init__]`, found `list[Unknown
| str]`
> +constructors_callable.py:194:22: error[invalid-argument-type]
Argument is incorrect: Expected `list[T@__init__]`, found `list[Unknown
| str]`
> +constructors_callable.py:195:4: error[invalid-argument-type] Argument
is incorrect: Expected `list[T@__init__]`, found `list[Unknown | int]`
> +constructors_callable.py:195:9: error[invalid-argument-type] Argument
is incorrect: Expected `list[T@__init__]`, found `list[Unknown | str]`
> ```
I might need to look into why this is happening...
> ```diff
> +generics_defaults.py:79:1: error[type-assertion-failure] Type
`type[Class_ParamSpec[(str, int, /)]]` does not match asserted type
`<class 'Class_ParamSpec'>`
> ```
which is on the following code
```py
DefaultP = ParamSpec("DefaultP", default=[str, int])
class Class_ParamSpec(Generic[DefaultP]): ...
assert_type(Class_ParamSpec, type[Class_ParamSpec[str, int]])
```
It's occurring because there's no equivalence relationship defined
between `ClassLiteral` and `KnownInstanceType::TypeGenericAlias` which
is what these types are.
Everything else looks good to me!
When converting a class (whether specialized or not) into a `Callable`
type, we should carry through any generic context that the constructor
has. This includes both the generic context of the class itself (if it's
generic) and of the constructor methods (if they are separately
generic).
To help test this, this also updates the `generic_context` extension
function to work on `Callable` types and unions; and adds a new
`into_callable` extension function that works just like
`CallableTypeOf`, but on value forms instead of type forms.
Pulled this out of #21551 for separate review.
## Summary
Closes https://github.com/astral-sh/ty/issues/957
As explained in https://github.com/astral-sh/ty/issues/957, literal
union types for recursively defined values can be widened early to
speed up the convergence of fixed-point iterations.
This PR achieves this by embedding a marker in `UnionType` that
distinguishes whether a value is recursively defined.
This also allows us to identify values that are not recursively
defined, so I've increased the limit on the number of elements in a
literal union type for such values.
Edit: while this PR doesn't provide the significant performance
improvement initially hoped for, it does have the benefit of allowing
the number of elements in a literal union to be raised above the salsa
limit, and indeed mypy_primer results revealed that a literal union of
220 elements was actually being used.
## Test Plan
`call/union.md` has been updated
Fixes https://github.com/astral-sh/ty/issues/1587
## Summary
Perform cycle normalization on typevar bounds and constraints (similar
to how it was already done for typevar defaults) in order to ensure
convergence in cyclic cases.
There might be another fix here that could avoid the cycle in many more
cases, where we don't eagerly evaluate typevar bounds/constraints on
explicit specialization, but just accept the given specialization and
later evaluate to see whether we need to emit a diagnostic on it. But
the current fix here is sufficient to solve the problem and matches the
patterns we use to ensure cycle convergence elsewhere, so it seems good
for now; left a TODO for the other idea.
This fix is sufficient to make us not panic, but not sufficient to get
the semantics fully correct; see the TODOs in the tests. I have ideas
for fixing that as well, but it seems worth at least getting this in to
fix the panic.
## Test Plan
Test that previously panicked now does not.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
This makes an importing file a required argument to module resolution,
and if the fast-path cached query fails to resolve the module, take the
slow-path uncached (could be cached if we want)
`desperately_resolve_module` which will walk up from the importing file
until it finds a `pyproject.toml` (arbitrary decision, we could try
every ancestor directory), at which point it takes one last desperate
attempt to use that directory as a search-path. We do not continue
walking up once we've found a `pyproject.toml` (arbitrary decision, we
could keep going up).
Running locally, this fixes every broken-for-workspace-reasons import in
pyx's workspace!
* Fixes https://github.com/astral-sh/ty/issues/1539
* Improves https://github.com/astral-sh/ty/issues/839
## Test Plan
The workspace tests see a huge improvement on most absolute imports.
## Summary
Star-imports can not just affect the state of symbols that they pull in,
they can also affect the state of members that are associated with those
symbols. For example, if `obj.attr` was previously narrowed from `int |
None` to `int`, and a star-import now overwrites `obj`, then the
narrowing on `obj.attr` should be "reset".
This PR keeps track of the state of associated members during star
imports and properly models the flow of their corresponding state
through the control flow structure that we artificially create for
star-imports.
See [this
comment](https://github.com/astral-sh/ty/issues/1355#issuecomment-3607125005)
for an explanation why this caused ty to see certain `asyncio` symbols
as not being accessible on Python 3.14.
closes https://github.com/astral-sh/ty/issues/1355
## Ecosystem impact
```diff
async-utils (https://github.com/mikeshardmind/async-utils)
- src/async_utils/bg_loop.py:115:31: error[invalid-argument-type] Argument to bound method `set_task_factory` is incorrect: Expected `_TaskFactory | None`, found `def eager_task_factory[_T_co](loop: AbstractEventLoop | None, coro: Coroutine[Any, Any, _T_co@eager_task_factory], *, name: str | None = None, context: Context | None = None) -> Task[_T_co@eager_task_factory]`
- Found 30 diagnostics
+ Found 29 diagnostics
mitmproxy (https://github.com/mitmproxy/mitmproxy)
+ mitmproxy/utils/asyncio_utils.py:96:60: warning[unused-ignore-comment] Unused blanket `type: ignore` directive
- test/conftest.py:37:31: error[invalid-argument-type] Argument to bound method `set_task_factory` is incorrect: Expected `_TaskFactory | None`, found `def eager_task_factory[_T_co](loop: AbstractEventLoop | None, coro: Coroutine[Any, Any, _T_co@eager_task_factory], *, name: str | None = None, context: Context | None = None) -> Task[_T_co@eager_task_factory]`
```
All of these seem to be correct, they give us a different type for
`asyncio` symbols that are now imported from different
`sys.version_info` branches (where we previously failed to recognize
some of these as statically true/false).
```diff
dd-trace-py (https://github.com/DataDog/dd-trace-py)
- ddtrace/contrib/internal/asyncio/patch.py:39:12: error[invalid-argument-type] Argument to function `unwrap` is incorrect: Expected `WrappedFunction`, found `def create_task[_T](self, coro: Coroutine[Any, Any, _T@create_task] | Generator[Any, None, _T@create_task], *, name: object = None) -> Task[_T@create_task]`
+ ddtrace/contrib/internal/asyncio/patch.py:39:12: error[invalid-argument-type] Argument to function `unwrap` is incorrect: Expected `WrappedFunction`, found `def create_task[_T](self, coro: Generator[Any, None, _T@create_task] | Coroutine[Any, Any, _T@create_task], *, name: object = None) -> Task[_T@create_task]`
```
Similar, but only results in a diagnostic change.
## Test Plan
Added a regression test
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.]
## 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.
## 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.
## 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.
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
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).
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.
## 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
## 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
## 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).
## 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.
## 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
## 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.
## 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.
## Summary
This PR updates the explicit specialization logic to avoid using the
call machinery.
Previously, the logic would use the call machinery by converting the
list of type variables into a `Binding` with a single `Signature` where
all the type variables are positional-only parameters with bounds and
constraints as the annotated type and the default type as the default
parameter value. This has the advantage that it doesn't need to
implement any specific logic but the disadvantages are subpar diagnostic
messages as it would use the ones specific to a function call. But, an
important disadvantage is that the kind of type variable is lost in this
translation which becomes important in #21445 where a `ParamSpec` can
specialize into a list of types which is provided using list literal.
For example,
```py
class Foo[T, **P]: ...
Foo[int, [int, str]]
```
This PR converts the logic to use a simple loop using `zip_longest` as
all type variables and their corresponding type argument maps on a 1-1
basis. They cannot be specified using keyword argument either e.g.,
`dict[_VT=str, _KT=int]` is invalid.
This PR also makes an initial attempt to improve the diagnostic message
to specifically target the specialization part by using words like "type
argument" instead of just "argument" and including information like the
type variable, bounds, and constraints. Further improvements can be made
by highlighting the type variable definition or the bounds / constraints
as a sub-diagnostic but I'm going to leave that as a follow-up.
## Test Plan
Update messages in existing test cases.
Charlie Marsh
Shunsuke Shibayama
Dhruv Manilawala
Douglas Creager
Alex Waygood
Carl Meyer
Aria Desires
David Peter
github-actions[bot]
Ibraheem Ahmed
Brent Westbrook
Micha Reiser