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Author SHA1 Message Date
David Peter
ac2c530377
[ty] Handle decorators which return unions of Callables (#20858)
## Summary

If a function is decorated with a decorator that returns a union of
`Callable`s, also treat it as a union of function-like `Callable`s.

Labeling as `internal`, since the previous change has not been released
yet.

## Test Plan

New regression test.
2025-10-14 09:47:50 +00:00
David Peter
f73bb45be6
[ty] Rename Type unwrapping methods (#20857)
## Summary

Rename "unwrapping" methods on `Type` from e.g.
`Type::into_class_literal` to `Type::as_class_literal`. I personally
find that name more intuitive, since no transformation of any kind is
happening. We are just unwrapping from certain enum variants. An
alternative would be `try_as_class_literal`, which would follow the
[`strum` naming
scheme](https://docs.rs/strum/latest/strum/derive.EnumTryAs.html), but
is slightly longer.

Also rename `Type::into_callable` to `Type::try_upcast_to_callable`.
Note that I intentionally kept names like
`FunctionType::into_callable_type`, because those return `CallableType`,
not `Option<Type<…>>`.

## Test Plan

Pure refactoring
2025-10-14 09:53:29 +02:00
Douglas Creager
5e08e5451d
[ty] Add separate type for typevar "identity" (#20813)
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As part of #20598, we added `is_identical_to` methods to
`TypeVarInstance` and `BoundTypeVarInstance`, which compare when two
typevar instances refer to "the same" underlying typevar, even if we
have forced their lazy bounds/constraints as part of marking typevars as
inferable. (Doing so results in a different salsa interned struct ID,
since we've changed the contents of the `bounds_or_constraints` field.)

It turns out that marking typevars as inferable is not the only way that
we might force lazy bounds/constraints; it also happens when we
materialize a type containing a typevar. This surfaced as ecosystem
report failures on #20677.

That means that we need a more long-term fix to this problem.
(`is_identical_to`, and its underlying `original` field, were meant to
be a temporary fix until we removed the `MarkTypeVarsInferable` type
mapping.)

This PR extracts out a separate type (`TypeVarIdentity`) that only
includes the fields that actually inform whether two typevars are "the
same". All other properties of the typevar (default, bounds/constraints,
etc) still live in `TypeVarInstance`. Call sites that care about typevar
identity can now either store just `TypeVarIdentity` (if they never need
access to those other properties), or continue to store
`TypeVarInstance` but pull out its `identity` when performing those "are
they the same typevar" comparisons. (All of this also applies
respectively to `BoundTypeVar{Identity,Instance}`.) In particular,
constraint sets now work on `BoundTypeVarIdentity`, and generic contexts
still _store_ a `BoundTypeVarInstance` (since we might need access to
defaults when specializing), but are keyed on `BoundTypeVarIdentity`.
2025-10-13 20:09:27 -04:00
Douglas Creager
aba0bd568e
[ty] Diagnostic for generic classes that reference typevars in enclosing scope (#20822)
Generic classes are not allowed to bind or reference a typevar from an
enclosing scope:

```py
def f[T](x: T, y: T) -> None:
    class Ok[S]: ...
    # error: [invalid-generic-class]
    class Bad1[T]: ...
    # error: [invalid-generic-class]
    class Bad2(Iterable[T]): ...

class C[T]:
    class Ok1[S]: ...
    # error: [invalid-generic-class]
    class Bad1[T]: ...
    # error: [invalid-generic-class]
    class Bad2(Iterable[T]): ...
```

It does not matter if the class uses PEP 695 or legacy syntax. It does
not matter if the enclosing scope is a generic class or function. The
generic class cannot even _reference_ an enclosing typevar in its base
class list.

This PR adds diagnostics for these cases.

In addition, the PR adds better fallback behavior for generic classes
that violate this rule: any enclosing typevars are not included in the
class's generic context. (That ensures that we don't inadvertently try
to infer specializations for those typevars in places where we
shouldn't.) The `dulwich` ecosystem project has [examples of
this](d912eaaffd/dulwich/config.py (L251))
that were causing new false positives on #20677.

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
2025-10-13 19:30:49 -04:00
Bhuminjay Soni
2b729b4d52
[syntax-errors]: break outside loop F701 (#20556)
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## Summary

<!-- What's the purpose of the change? What does it do, and why? -->

This PR implements https://docs.astral.sh/ruff/rules/break-outside-loop/
(F701) as a semantic syntax error.

## Test Plan

<!-- How was it tested? -->

---------

Signed-off-by: 11happy <soni5happy@gmail.com>
Co-authored-by: Brent Westbrook <brentrwestbrook@gmail.com>
2025-10-13 20:00:59 +00:00
David Peter
4b8e278a88
[ty] Treat Callables as bound-method descriptors in special cases (#20802)
## Summary

Treat `Callable`s as bound-method descriptors if `Callable` is the
return type of a decorator that is applied to a function definition. See
the [rendered version of the new test
file](https://github.com/astral-sh/ruff/blob/david/callables-as-descriptors/crates/ty_python_semantic/resources/mdtest/call/callables_as_descriptors.md)
for the full description of this new heuristic.

I could imagine that we want to treat `Callable`s as bound-method
descriptors in other cases as well, but this seems like a step in the
right direction. I am planning to add other "use cases" from
https://github.com/astral-sh/ty/issues/491 to this test suite.

partially addresses https://github.com/astral-sh/ty/issues/491
closes https://github.com/astral-sh/ty/issues/1333

## Ecosystem impact

All positive

* 2961 removed `unsupported-operator` diagnostics on `sympy`, which was
one of the main motivations for implementing this change
* 37 removed `missing-argument` diagnostics, and no added call-error
diagnostics, which is an indicator that this heuristic shouldn't cause
many false positives
* A few removed `possibly-missing-attribute` diagnostics when accessing
attributes like `__name__` on decorated functions. The two added
`unused-ignore-comment` diagnostics are also cases of this.
* One new `invalid-assignment` diagnostic on `dd-trace-py`, which looks
suspicious, but only because our `invalid-assignment` diagnostics are
not great. This is actually a "Implicit shadowing of function"
diagnostic that hides behind the `invalid-assignment` diagnostic,
because a module-global function is being patched through a
`module.func` attribute assignment.

## Test Plan

New Markdown tests.
2025-10-13 21:17:47 +02:00
David Peter
d912f13661
[ty] Do not bind self to non-positional parameters (#20850)
## Summary

closes https://github.com/astral-sh/ty/issues/1333

## Test Plan

Regression test
2025-10-13 20:44:27 +02:00
David Peter
195e8f0684
[ty] Treat functions, methods, and dynamic types as function-like Callables (#20842)
## Summary

Treat functions, methods, and dynamic types as function-like `Callable`s

closes https://github.com/astral-sh/ty/issues/1342
closes https://github.com/astral-sh/ty/issues/1344

## Ecosystem analysis

All removed diagnostics look like cases of
https://github.com/astral-sh/ty/issues/1344

## Test Plan

Added regression test
2025-10-13 15:21:55 +02:00
Alex Waygood
513d2996ec
[ty] Move logic for super() inference to a new types::bound_super submodule (#20840)
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2025-10-13 11:18:13 +00:00
Alex Waygood
d83d7a0dcd
[ty] Fix false-positive diagnostics on super() calls (#20814) 2025-10-13 10:57:46 +00:00
David Peter
565dbf3c9d
[ty] Move class_member to member module (#20837)
## Summary

Move the `class_member` function to the `member` module. This allows us
to move the `member` module into the `types` module and to reduce the
visibility of its contents to `pub(super)`. The drawback is that we need
to make `place::place_by_id` public.

## Test Plan

Pure refactoring.
2025-10-13 10:58:37 +02:00
David Peter
9b9c9ae092
[ty] Prefer declared base class attribute over inferred attribute on subclass (#20764)
## Summary

When accessing an (instance) attribute on a given class, we were
previously traversing its MRO, and building a union of types (if the
attribute was available on multiple classes in the MRO) until we found a
*definitely bound* symbol. The idea was that possibly unbound symbols in
a subclass might only partially shadow the underlying base class
attribute.

This behavior was problematic for two reasons:
* if the attribute was definitely bound on a class (e.g. `self.x =
None`), we would have stopped iterating, even if there might be a `x:
str | None` declaration in a base class (the bug reported in
https://github.com/astral-sh/ty/issues/1067).
* if the attribute originated from an implicit instance attribute
assignment (e.g. `self.x = 1` in method `Sub.foo`), we might stop
looking and miss another implicit instance attribute assignment in a
base class method (e.g. `self.x = 2` in method `Base.bar`).

With this fix, we still iterate the MRO of the class, but we only stop
iterating if we find a *definitely declared* symbol. In this case, we
only return the declared attribute type. Otherwise, we keep building a
union of inferred attribute types.

The implementation here seemed to be the easiest fix for
https://github.com/astral-sh/ty/issues/1067 that also kept the ecosystem
impact low (the changes that I see all look correct). However, as the
Markdown tests show, there are other things to fix in this area. For
example, we should do a similar thing for *class attributes*. This is
more involved, though (affects many different areas and probably
involves a change to our descriptor protocol implementation), so I'd
like to postpone this to a follow-up.

closes https://github.com/astral-sh/ty/issues/1067

## Test Plan

Updated Markdown tests, including a regression test for
https://github.com/astral-sh/ty/issues/1067.
2025-10-13 09:28:57 +02:00
Micha Reiser
c80ee1a50b
[ty] Log files that are slow to type check (#20836) 2025-10-13 09:15:54 +02:00
Alex Waygood
7064c38e53
[ty] Filter out revealed-type and undefined-reveal diagnostics from mdtest snapshots (#20820)
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2025-10-12 18:39:32 +00:00
Shunsuke Shibayama
dc64c08633
[ty] bidirectional type inference using function return type annotations (#20528)
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## Summary

Implements bidirectional type inference using function return type
annotations.

This PR was originally proposed to solve astral-sh/ty#1167, but this
does not fully resolve it on its own.
Additionally, I believe we need to allow dataclasses to generate their
own `__new__` methods, [use constructor return types ​​for
inference](5844c0103d/crates/ty_python_semantic/src/types.rs (L5326-L5328)),
and a mechanism to discard type narrowing like `& ~AlwaysFalsy` if
necessary (at a more general level than this PR).

## Test Plan

`mdtest/bidirectional.md` is added.

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
Co-authored-by: Ibraheem Ahmed <ibraheem@ibraheem.ca>
2025-10-11 00:38:35 +00:00
Shunsuke Shibayama
11a9e7ee44
[ty] use type context more aggressively to infer values ​​when constructing a TypedDict (#20806)
## Summary

Based on @ibraheemdev's comment on #20792:

> I think we can also update our bidirectional inference code, [which
makes the same
assumption](https://github.com/astral-sh/ruff/blob/main/crates/ty_python_semantic/src/types/infer/builder.rs?rgh-link-date=2025-10-09T21%3A30%3A31Z#L5860).

This PR also adds more test cases for how `TypedDict` annotations affect
generic call inference.

## Test Plan

New tests in `typed_dict.md`
2025-10-10 16:51:16 -07:00
David Peter
ae83a1fd2d
[ty] Additional tests for dataclass_transform (class-level overwrites, field_specifiers) (#20788)
## Summary

Adds a set of basic new tests corresponding to open points in
https://github.com/astral-sh/ty/issues/1327, to document the state of
support for `dataclass_transform`.
2025-10-10 11:22:06 +00:00
Alex Waygood
44807c4a05
[ty] Better implementation of assignability for intersections with negated gradual elements (#20773) 2025-10-10 11:10:17 +00:00
David Peter
69f9182033
[ty] Annotations are deferred by default for 3.14+ (#20799)
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## Summary

Type annotations are deferred by default starting with Python 3.14. No
`from __future__ import annotations` import is necessary.

## Test Plan

New Markdown test
2025-10-10 12:05:03 +02:00
David Peter
949a4f1c42
[ty] Simplify and fix CallableTypeOf[..] implementation (#20797)
## Summary

Simplify and fix the implementation of
`ty_extensions.CallableTypeOf[..]`.

closes https://github.com/astral-sh/ty/issues/1331

## Test Plan

Added regression test.
2025-10-10 12:04:37 +02:00
David Peter
a82833a998
[ty] Update mypy_primer and project lists (#20798)
## Summary

Pulls in two updates to `mypy_primer` projects:

* https://github.com/hauntsaninja/mypy_primer/pull/201 (add
`django-test-migrations`)
* https://github.com/hauntsaninja/mypy_primer/pull/122 (remove
`SinbadCogs`)

## Test Plan

CI on this PR
2025-10-10 11:08:39 +02:00
Carl Meyer
8248193ed9
[ty] defer inference of legacy TypeVar bound/constraints/defaults (#20598)
## Summary

This allows us to handle self-referential bounds/constraints/defaults
without panicking.

Handles more cases from https://github.com/astral-sh/ty/issues/256

This also changes the way we infer the types of legacy TypeVars. Rather
than understanding a constructor call to `typing[_extension].TypeVar`
inside of any (arbitrarily nested) expression, and having to use a
special `assigned_to` field of the semantic index to try to best-effort
figure out what name the typevar was assigned to, we instead understand
the creation of a legacy `TypeVar` only in the supported syntactic
position (RHS of a simple un-annotated assignment with one target). In
any other position, we just infer it as creating an opaque instance of
`typing.TypeVar`. (This behavior matches all other type checkers.)

So we now special-case TypeVar creation in `TypeInferenceBuilder`, as a
special case of an assignment definition, rather than deeper inside call
binding. This does mean we re-implement slightly more of
argument-parsing, but in practice this is minimal and easy to handle
correctly.

This is easier to implement if we also make the RHS of a simple (no
unpacking) one-target assignment statement no longer a standalone
expression. Which is fine to do, because simple one-target assignments
don't need to infer the RHS more than once. This is a bonus performance
(0-3% across various projects) and significant memory-usage win, since
most assignment statements are simple one-target assignment statements,
meaning we now create many fewer standalone-expression salsa
ingredients.

This change does mean that inference of manually-constructed
`TypeAliasType` instances can no longer find its Definition in
`assigned_to`, which regresses go-to-definition for these aliases. In a
future PR, `TypeAliasType` will receive the same treatment that
`TypeVar` did in this PR (moving its special-case inference into
`TypeInferenceBuilder` and supporting it only in the correct syntactic
position, and lazily inferring its value type to support recursion),
which will also fix the go-to-definition regression. (I decided a
temporary edge-case regression is better in this case than doubling the
size of this PR.)

This PR also tightens up and fixes various aspects of the validation of
`TypeVar` creation, as seen in the tests.

We still (for now) treat all typevars as instances of `typing.TypeVar`,
even if they were created using `typing_extensions.TypeVar`. This means
we'll wrongly error on e.g. `T.__default__` on Python 3.11, even if `T`
is a `typing_extensions.TypeVar` instance at runtime. We share this
wrong behavior with both mypy and pyrefly. It will be easier to fix
after we pull in https://github.com/python/typeshed/pull/14840.

There are some issues that showed up here with typevar identity and
`MarkTypeVarsInferable`; the fix here (using the new `original` field
and `is_identical_to` methods on `BoundTypeVarInstance` and
`TypeVarInstance`) is a bit kludgy, but it can go away when we eliminate
`MarkTypeVarsInferable`.

## Test Plan

Added and updated mdtests.

### Conformance suite impact

The impact here is all positive:

* We now correctly error on a legacy TypeVar with exactly one constraint
type given.
* We now correctly error on a legacy TypeVar with both an upper bound
and constraints specified.

### Ecosystem impact

Basically none; in the setuptools case we just issue slightly different
errors on an invalid TypeVar definition, due to the modified validation
code.

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
2025-10-09 21:08:37 +00:00
Ibraheem Ahmed
b086ffe921
[ty] Type-context aware literal promotion (#20776)
## Summary

Avoid literal promotion when a literal type annotation is provided, e.g.,
```py
x: list[Literal[1]] = [1]
```

Resolves https://github.com/astral-sh/ty/issues/1198. This does not fix
issue https://github.com/astral-sh/ty/issues/1284, but it does make it
more relevant because after this change, it is possible to directly
instantiate a generic type with a literal specialization.
2025-10-09 16:53:53 -04:00
Shunsuke Shibayama
db91ac7dce
[ty] allow any string Literal type expression as a key when constructing a TypedDict (#20792) 2025-10-09 18:24:11 +00:00
David Peter
75f3c0e8e6
[ty] Respect dataclass_transform parameters for metaclass-based models (#20780)
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## Summary

Respect parameters such as `frozen_default` for metaclass-based
`@dataclass_transformer` models.

Related to: https://github.com/astral-sh/ty/issues/1260

## Typing conformance changes

Those are all correct (new true positives)

## Test Plan

New Markdown tests
2025-10-09 13:24:20 +00:00
wangxiaolei
f0d0b57900
[ty] dataclass_transform: Support frozen_default and kw_only_default (#20761)
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## Summary

- Add support for eq, kw_only, and frozen parameter overrides in
@dataclass_transform
- Previously only order parameter override was supported
- Update test documentation to reflect fixed behavior
- Resolves issue where kw_only_default and frozen_default could not be
overridden

closes https://github.com/astral-sh/ty/issues/1260

## Test Plan

New Markdown tests

---------

Co-authored-by: David Peter <mail@david-peter.de>
2025-10-09 09:34:49 +02:00
Alex Waygood
b0c6217e0b
[ty] Fix broken property tests for disjointness of intersections (#20775)
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## Summary

Two stable property tests are currently failing on `main`, following
f054b8a55e
(of course, I only thought to run the property tests again around 30
minutes _after_ landing that PR...). The issue is quite subtle, and took
me an annoying amount of time to pin down: we're matching over `(self,
other)` in `Type::is_disjoint_from_impl`, but `other` here is shadowed
by the binding in the `match` branch, which means that the wrong key is
inserted into the cache of the `IsDisjointFrom` cycle detector:


f054b8a55e/crates/ty_python_semantic/src/types.rs (L2408-L2435)

This PR fixes that issue, and also adds a few `Debug` implementations to
our cycle detectors, so that issues like this are easier to debug in the
future.

I'm adding the `internal` label, as this fixes a bug that hasn't yet
appeared in any released version of ty, so it doesn't deserve its own
changelog entry.

## Test Plan

`QUICKCHECK_TESTS=1000000 cargo test --release -p ty_python_semantic --
--ignored types::property_tests::stable` now once again passes on `main`

I considered adding new mdtests as well, but the examples that the
property tests were throwing at me all seemed _quite_ obscure and
somewhat unlikely to occur in the real world. I don't think it's worth
it.
2025-10-08 22:28:56 +01:00
Alex Waygood
f054b8a55e
[ty] Improve assignability/subtyping between two protocol types (#20368) 2025-10-08 18:37:30 +00:00
Alex Waygood
b9c84add07
[ty] Disambiguate classes that live in different modules but have the same fully qualified names (#20756)
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## Summary

Even disambiguating classes using their fully qualified names is not
enough for some diagnostics. We've seen real-world examples in the
ecosystem (and https://github.com/astral-sh/ruff/pull/20368 introduces
some more!) where two types can be different, but can still have the
same fully qualified name. In these cases, our disambiguation machinery
needs to print the file path and line number of the class in order to
disambiguate classes with similar names in our diagnostics.

Helps with https://github.com/astral-sh/ty/issues/1306

## Test Plan

Mdtests
2025-10-08 18:27:40 +01:00
David Peter
150ea92d03
[ty] Add tests for instance attributes in class hierarchies (#20767)
## Summary

This adds a couple of new test cases related to
https://github.com/astral-sh/ty/issues/1067 and beyond that. For now,
they are just documenting the current (problematic) behavior. Since the
topic has some subtleties, I'd like to merge this prior to the actual
bugfix(es) in order to evaluate the changes in an easier way.
2025-10-08 17:46:47 +02:00
David Peter
697998f836
[ty] Do not re-export ide_support attributes from types (#20769)
## Summary

The `types` module currently re-exports a lot of functions and data
types from `types::ide_support`. One of these is called `Member`, a name
that is overloaded several times already. And I'd like to add one more
`Member` struct soon. Making the whole `ide_support` module public seems
cleaner to me, anyway.

## Test Plan

Pure refactoring.
2025-10-08 17:45:28 +02:00
David Peter
6b94e620fe
[ty] Fix accidental Liskov violation in protocol tests (#20763)
## Summary

We have the following test in `protocols.md`:
```py
class HasX(Protocol):
    x: int

# […]

class Foo:
    x: int

# […]

class FooBool(Foo):
    x: bool

static_assert(not is_subtype_of(FooBool, HasX))
static_assert(not is_assignable_to(FooBool, HasX))
```

If `Foo` was indeed intended to be a base class of `FooBool`, then `x:
bool` should be reported as a Liskov violation. And then it's a matter
of definition whether or not these assertions should hold true or not
(should the incorrect override take precedence or not?). So it looks to
me like this is just an oversight, probably a copy-paste error from
another test right before it, where `FooSub` is indeed intended to be a
subclass of `Foo`.

I am fixing this because this test started to fail on a branch of mine
that changes how attribute lookup in inheritance chains works.
2025-10-08 14:04:37 +02:00
Mark Z. Ding
f95eb90951
[ty] Truncate type display for long unions in some situations (#20730)
## Summary

Fixes [astral-sh/ty#1307](https://github.com/astral-sh/ty/issues/1307)

Unions with length <= 5 are unaffected to minimize test churn
Unions with length > 5 will only display the first 3 elements + "...
omitted x union elements"
Here "length" is defined as the number of elements after condensation to
literals

Edit: we no longer truncate in revel case. 
Before:

> info: Attempted to call union type `(def f1() -> int) | (def f2(name:
str) -> int) | (def f3(a: int, b: int) -> int) | (def f4[T](x: T@f4) ->
int) | Literal[5] | (Overload[() -> None, (x: str) -> str]) |
(Overload[() -> None, (x: str, y: str) -> str]) | PossiblyNotCallable`

After:

> info: Attempted to call union type `(def f1() -> int) | (def f2(name:
str) -> int) | (def f3(a: int, b: int) -> int) | ... omitted 5 union
elements`

The below comparisons are outdated, but left here as a reference.

Before:
```reveal_type(x)  # revealed: Literal[1, 2] | A | B | C | D | E | F | G```
```reveal_type(x) # revealed: Result1A | Result1B | Result2A | Result2B
| Result3 | Result4```
After:
```reveal_type(x)  # revealed: Literal[1, 2] | A | B | ... omitted 5 union elements```
```reveal_type(x) # revealed: Result1A | Result1B | Result2A | ...
omitted 3 union elements```

This formatting is consistent with
`crates/ty_python_semantic/src/types/call/bind.rs` line 2992

## Test Plan

Cosmetic only, covered and verified by changes in mdtest
2025-10-08 11:21:26 +01:00
David Peter
1f1542db51
[ty] Use 3.14 as the default version (#20759)
## Summary

Bump the latest supported Python version of ty to 3.14 and updates some
references from 3.13 to 3.14.

This also fixes a bug with `dataclasses.field` on 3.14 (which adds a new
keyword-only parameter to that function, breaking our previously naive
matching on the parameter structure of that function).

## Test Plan

A `ty check` on a file with template strings (without any further
configuration) doesn't raise errors anymore.
2025-10-08 11:38:47 +02:00
Carl Meyer
5d3a35e071
[ty] fix implicit Self on generic class with typevar default (#20754)
## Summary

Typevar attributes (bound/constraints/default) can be either lazily
evaluated or eagerly evaluated. Currently they are lazily evaluated for
PEP 695 typevars, and eager for legacy and synthetic typevars.
https://github.com/astral-sh/ruff/pull/20598 will make them lazy also
for legacy typevars, and the ecosystem report on that PR surfaced the
issue fixed here (because legacy typevars are much more common in the
ecosystem than PEP 695 typevars.)

Applying a transform to a typevar (normalization, materialization, or
mark-inferable) will reify all lazy attributes and create a new typevar
with eager attributes. In terms of Salsa identity, this transformed
typevar will be considered different from the original typevar, whether
or not the attributes were actually transformed.

In general, this is not a problem, since all typevars in a given generic
context will be transformed, or not, together.

The exception to this was implicit-self vs explicit Self annotations.
The typevar we created for implicit self was created initially using
inferable typevars, whereas an explicit Self annotation is initially
non-inferable, then transformed via mark-inferable when accessed as part
of a function signature. If the containing class (which becomes the
upper bound of `Self`) is generic, and has e.g. a lazily-evaluated
default, then the explicit-Self annotation will reify that default in
the upper bound, and the implicit-self would not, leading them to be
treated as different typevars, and causing us to fail to solve a call to
a method such as `def method(self) -> Self` correctly.

The fix here is to treat implicit-self more like explicit-Self,
initially creating it as non-inferable and then using the mark-inferable
transform on it. This is less efficient, but restores the invariant that
all typevars in a given generic context are transformed together, or
not, fixing the bug.

In the improved-constraint-solver work, the separation of typevars into
"inferable" and "non-inferable" is expected to disappear, along with the
mark-inferable transform, which would render both this bug and the fix
moot. So this fix is really just temporary until that lands.

There is a performance regression, but not a huge one: 1-2% on most
projects, 5% on one outlier. This seems acceptable, given that it should
be fully recovered by removing the mark-inferable transform.

## Test Plan

Added mdtests that failed before this change.
2025-10-08 01:38:24 +00:00
Alex Waygood
ff386b4797
[ty] Improve diagnostics for bad @overload definitions (#20745)
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2025-10-07 21:52:57 +00:00
Douglas Creager
416e956fe0
[ty] Infer better specializations of unions with None (etc) (#20749)
This PR adds a specialization inference special case that lets us handle
the following examples better:

```py
def f[T](t: T | None) -> T: ...
def g[T](t: T | int | None) -> T | int: ...

def _(x: str | None):
    reveal_type(f(x))  # revealed: str (previously str | None)

def _(y: str | int | None):
    reveal_type(g(x))  # revealed: str | int (previously str | int | None)
```

We already have a special case for when the formal is a union where one
element is a typevar, but it maps the entire actual type to the typevar
(as you can see in the "previously" results above).

The new special case kicks in when the actual is also a union. Now, we
filter out any actual union elements that are already subtypes of the
formal, and only bind whatever types remain to the typevar. (The `|
None` pattern appears quite often in the ecosystem results, but it's
more general and works with any number of non-typevar union elements.)

The new constraint solver should handle this case as well, but it's
worth adding this heuristic now with the old solver because it
eliminates some false positives from the ecosystem report, and makes the
ecosystem report less noisy on the other constraint solver PRs.
2025-10-07 13:33:42 -04:00
Brent Westbrook
88c0ce3e38
Update default and latest Python versions for 3.14 (#20725)
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Summary
--

Closes #19467 and also removes the warning about using Python 3.14
without
preview enabled.

I also bumped `PythonVersion::default` to 3.9 because it reaches EOL
this month,
but we could also defer that for now if we wanted.

The first three commits are related to the `latest` bump to 3.14; the
fourth commit
bumps the default to 3.10.

Note that this PR also bumps the default Python version for ty to 3.10
because
there was a test asserting that it stays in sync with
`ast::PythonVersion`.

Test Plan
--

Existing tests

I spot-checked the ecosystem report, and I believe these are all
expected. Inbits doesn't specify a target Python version, so I guess
we're applying the default. UP007, UP035, and UP045 all use the new
default value to emit new diagnostics.
2025-10-07 12:23:11 -04:00
David Peter
23ebfe7777
[ty] Fix tiny mistake in protocol tests (#20743) 2025-10-07 11:58:35 +00:00
David Peter
f90d6466e0
[ty] Make infer_method_information less confusing (#20740)
## Summary

`infer_method_information` was previously calling
`ClassLiteral::to_class_type`, which uses the default-specialization of
a generic class. This specialized `ClassType` was later only used if the
class was non-generic, making the specialization irrelevant. The
implementation was still a bit confusing, so this PR proposes a way to
avoid turning the class literal into a `ClassType`.
2025-10-07 10:12:23 +00:00
Alex Waygood
70f51e9648
[ty] Print display of types when a property test fails (#20720)
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2025-10-06 14:44:24 +01:00
Alex Waygood
1ce57edf33
[ty] Enforce that typing_extensions must come from a stdlib search path (#20715) 2025-10-06 11:43:34 +00:00
Ibraheem Ahmed
2ce3aba458
[ty] Use annotated parameters as type context (#20635)
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## Summary

Use the type annotation of function parameters as bidirectional type
context when inferring the argument expression. For example, the
following example now type-checks:

```py
class TD(TypedDict):
    x: int

def f(_: TD): ...

f({ "x": 1 })
```

Part of https://github.com/astral-sh/ty/issues/168.
2025-10-03 17:14:51 -04:00
Douglas Creager
b83ac5e234
[ty] Clean up inherited generic contexts (#20647)
We add an `inherited_generic_context` to the constructors of a generic
class. That lets us infer specializations of the class when invoking the
constructor. The constructor might itself be generic, in which case we
have to merge the list of typevars that we are willing to infer in the
constructor call.

Before we did that by tracking the two (and their specializations)
separately, with distinct `Option` fields/parameters. This PR updates
our call binding logic such that any given function call has _one_
optional generic context that we're willing to infer a specialization
for. If needed, we use the existing `GenericContext::merge` method to
create a new combined generic context for when the class and constructor
are both generic. This simplifies the call binding code considerably,
and is no more complex in the constructor call logic.

We also have a heuristic that we will promote any literals in the
specialized types of a generic class, but we don't promote literals in
the specialized types of the function itself. To handle this, we now
track this `should_promote_literals` property within `GenericContext`.
And moreover, we track this separately for each typevar, instead of a
single property for the generic context as a whole, so that we can
correctly merge the generic context of a constructor method (where the
option should be `false`) with the inherited generic context of its
containing class (where the option should be `true`).

---------

Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
2025-10-03 13:55:43 -04:00
Alex Waygood
c91b457044
[ty] Introduce TypeRelation::Redundancy (#20602)
## Summary

The union `T | U` can be validly simplified to `U` iff:
1. `T` is a subtype of `U` OR
2. `T` is equivalent to `U` OR
3. `U` is a union and contains a type that is equivalent to `T` OR
4. `T` is an intersection and contains a type that is equivalent to `U`

(In practice, the only situation in which 2, 3 or 4 would be true when
(1) was not true would be if `T` or `U` is a dynamic type.)

Currently we achieve these simplifications in the union builder by doing
something along the lines of `t.is_subtype_of(db, u) ||
t.is_equivalent_to_(db, u) ||
t.into_intersection().is_some_and(|intersection|
intersection.positive(db).contains(&u)) ||
u.into_union().is_some_and(|union| union.elements(db).contains(&t))`.
But this is both slow and misses some cases (it doesn't simplify the
union `Any | (Unknown & ~None)` to `Any`, for example). We can improve
the consistency and performance of our union simplifications by adding a
third type relation that sits in between `TypeRelation::Subtyping` and
`TypeRelation::Assignability`: `TypeRelation::UnionSimplification`.

This change leads to simpler, more user-friendly types due to the more
consistent simplification. It also lead to a pretty huge performance
improvement!

## Test Plan

Existing tests, plus some new ones.
2025-10-03 18:35:30 +01:00
Daniel Kongsgaard
f73ead11cb
[ty] improve base conda distinction from child conda (#20675)
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## Summary

#19990 didn't completely fix the base vs. child conda environment
distinction, since it detected slightly different behavior than what I
usually see in conda. E.g., I see something like the following:
```
(didn't yet activate conda, but base is active)
➜ printenv | grep CONDA
CONDA_PYTHON_EXE=/opt/anaconda3/bin/python
CONDA_PREFIX=/opt/anaconda3
CONDA_DEFAULT_ENV=base
CONDA_EXE=/opt/anaconda3/bin/conda
CONDA_SHLVL=1
CONDA_PROMPT_MODIFIER=(base)

(activating conda)
➜ conda activate test

(test is an active conda environment)
❯ printenv | grep CONDA
CONDA_PREFIX=/opt/anaconda3/envs/test
CONDA_PYTHON_EXE=/opt/anaconda3/bin/python
CONDA_SHLVL=2
CONDA_PREFIX_1=/opt/anaconda3
CONDA_DEFAULT_ENV=test
CONDA_PROMPT_MODIFIER=(test)
CONDA_EXE=/opt/anaconda3/bin/conda
```

But the current behavior looks for `CONDA_DEFAULT_ENV =
basename(CONDA_PREFIX)` for the base environment instead of the child
environment, where we actually see this equality.

This pull request fixes that and updates the tests correspondingly.

## Test Plan

I updated the existing tests with the new behavior. Let me know if you
want more tests. Note: It shouldn't be necessary to test for the case
where we have `conda/envs/base`, since one should not be able to create
such an environment (one with the name of `CONDA_DEFAULT_ENV`).

---------

Co-authored-by: Aria Desires <aria.desires@gmail.com>
2025-10-03 13:56:06 +00:00
Andrew Gallant
92eee816ed [ty] Fix file root matching for /
Previously, we would always add `/{*filepath}` as our wildcard to match
descendant paths. But when the root is just `/` (as it can be in tests,
weird environments or in the ty playground), this causes a double `/`
and inhibits most descendant matches.

The regression test added in this commit fails without this fix.
Specifically, it panics because it can't find a file root for
`/project`.

Fixes #1277
2025-10-03 08:18:03 -04:00
Dhruv Manilawala
4e94b22815
[ty] Support single-starred argument for overload call (#20223)
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## Summary

closes: https://github.com/astral-sh/ty/issues/247

This PR adds support for variadic arguments to overload call evaluation.

This basically boils down to making sure that the overloads are not
filtered out incorrectly during the step 5 in the overload call
evaluation algorithm. For context, the step 5 tries to filter out the
remaining overloads after finding an overload where the materialization
of argument types are assignable to the parameter types.

The issue with the previous implementation was that it wouldn't unpack
the variadic argument and wouldn't consider the many-to-one (multiple
arguments mapping to a single variadic parameter) correctly. This PR
fixes that.

## Test Plan

Update existing test cases and resolve the TODOs.
2025-10-02 10:41:56 -04:00
Alex Waygood
0639da2552
[ty] ~T should never be assignable to T (#20606)
## Summary

Currently we do not emit an error on this code:

```py
from ty_extensions import Not

def f[T](x: T, y: Not[T]) -> T:
    x = y
    return x
```

But we should do! `~T` should never be assignable to `T`.

This fixes a small regression introduced in
14fe1228e7 (diff-8049ab5af787dba29daa389bbe2b691560c15461ef536f122b1beab112a4b48aR1443-R1446),
where a branch that previously returned `false` was replaced with a
branch that returns `C::always_satisfiable` -- the opposite of what it
used to be! The regression occurred because we didn't have any tests for
this -- so I added some tests in this PR that fail on `main`. I only
spotted the problem because I was going through the code of
`has_relation_to_impl` with a fine toothcomb for
https://github.com/astral-sh/ruff/pull/20602 😄
2025-10-02 07:52:47 +01:00
David Peter
71d711257a
[ty] No union with Unknown for module-global symbols (#20664)
## Summary

Quoting from the newly added comment:

Module-level globals can be mutated externally. A `MY_CONSTANT = 1`
global might be changed to `"some string"` from code outside of the
module that we're looking at, and so from a gradual-guarantee
perspective, it makes sense to infer a type of `Literal[1] | Unknown`
for global symbols. This allows the code that does the mutation to type
check correctly, and for code that uses the global, it accurately
reflects the lack of knowledge about the type.

External modifications (or modifications through `global` statements)
that would require a wider type are relatively rare. From a practical
perspective, we can therefore achieve a better user experience by
trusting the inferred type. Users who need the external mutation to work
can always annotate the global with the wider type. And everyone else
benefits from more precise type inference.

I initially implemented this by applying literal promotion to the type
of the unannotated module globals (as suggested in
https://github.com/astral-sh/ty/issues/1069), but the ecosystem impact
showed a lot of problems (https://github.com/astral-sh/ruff/pull/20643).
I fixed/patched some of these problems, but this PR seems like a good
first step, and it seems sensible to apply the literal promotion change
in a second step that can be evaluated separately.

closes https://github.com/astral-sh/ty/issues/1069

## Ecosystem impact

This seems like an (unexpectedly large) net positive with 650 fewer
diagnostics overall.. even though this change will certainly catch more
true positives.

* There are 666 removed `type-assertion-failure` diagnostics, where we
were previously used the correct type already, but removing the
`Unknown` now leads to an "exact" match.
* 1464 of the 1805 total new diagnostics are `unresolved-attribute`
errors, most (1365) of which were previously
`possibly-missing-attribute` errors. So they could also be counted as
"changed" diagnostics.
* For code that uses constants like
  ```py
  IS_PYTHON_AT_LEAST_3_10 = sys.version_info >= (3, 10)
  ```
where we would have previously inferred a type of `Literal[True/False] |
Unknown`, removing the `Unknown` now allows us to do reachability
analysis on branches that use these constants, and so we get a lot of
favorable ecosystem changes because of that.
* There is code like the following, where we previously emitted
`conflicting-argument-forms` diagnostics on calls to the aliased
`assert_type`, because its type was `Unknown | def …` (and the call to
`Unknown` "used" the type form argument in a non type-form way):
  ```py
  if sys.version_info >= (3, 11):
      import typing
  
      assert_type = typing.assert_type
  else:
      import typing_extensions
  
      assert_type = typing_extensions.assert_type
  ```
* ~100 new `invalid-argument-type` false positives, due to missing
`**kwargs` support (https://github.com/astral-sh/ty/issues/247)

## Typing conformance

```diff
+protocols_modules.py:25:1: error[invalid-assignment] Object of type `<module '_protocols_modules1'>` is not assignable to `Options1`
```

This diagnostic should apparently not be there, but it looks like we
also fail other tests in that file, so it seems to be a limitation that
was previously hidden by `Unknown` somehow.

## Test Plan

Updated tests and relatively thorough ecosystem analysis.
2025-10-01 16:40:30 +02:00