## Summary
Provides a message like:
```
error[invalid-argument-type]: Cannot delete required key "name" from TypedDict `Movie`
--> test.py:15:7
|
15 | del m["name"]
| ^^^^^^
|
info: Field defined here
--> test.py:4:5
|
4 | name: str
| --------- `name` declared as required here; consider making it `NotRequired`
|
info: Only keys marked as `NotRequired` (or in a TypedDict with `total=False`) can be deleted
```
## Summary
TypedDict now synthesizes a proper `__delitem__` method that...
- ...allows deletion of `NotRequired` keys and keys in `total=False`
TypedDicts.
- ...rejects deletion of required keys (synthesizes `__delitem__(k:
Never)`).
## Summary
We already had `CallableTypeKind::ClassMethodLike` to track callables
that behave like `classmethods` (always bind the first argument). This
PR adds the symmetric `CallableTypeKind::StaticMethodLike` for callables
that behave like `staticmethods` (never bind `self`).
Closes https://github.com/astral-sh/ty/issues/2114.
## Summary
Previously, `del x[k]` incorrectly required the object to have a
`__getitem__` method. This was wrong because deletion only needs
`__delitem__`, which is independent of `__getitem__`.
Closes https://github.com/astral-sh/ty/issues/1799.
## Summary
This PR fixes https://github.com/astral-sh/ty/issues/1848.
```python
T = tuple[int, 'U']
class C(set['U']):
pass
type U = T | C
```
The reason why the fixed point iteration did not converge was because
the types stored in the implicit tuple type alias `Specialization`
changed each time.
```
1st: <class 'tuple[int, C]'>
2nd: <class 'tuple[int, tuple[int, C] | C]'>
3rd: <class 'tuple[int, tuple[int, tuple[int, C] | C] | C]'>
...
```
And this was because `UnionType::from_elements` was used when creating
union types for tuple operations, which causes type aliases inside to be
expanded.
This PR replaces these with `UnionType::from_elements_leave_aliases`.
## Test Plan
New corpus test
Identify and narrow cases like this:
```py
class Foo(TypedDict):
tag: Literal["foo"]
class Bar(TypedDict):
tag: Literal["bar"]
def _(union: Foo | Bar):
if union["tag"] == "foo":
reveal_type(union) # Foo
```
Fixes part of https://github.com/astral-sh/ty/issues/1479.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
## Summary
This PR fixes https://github.com/astral-sh/ty/issues/2085.
Based on the reported code, the panicking MRE is:
```python
class Test:
def __init__(self, x: int):
self.left = x
self.right = x
def method(self):
self.left, self.right = self.right, self.left
if self.right:
self.right = self.right
```
The type inference (`implicit_attribute_inner`) for `self.right`
proceeds as follows:
```
0: Divergent(Id(6c07))
1: Unknown | int | (Divergent(Id(1c00)) & ~AlwaysFalsy)
2: Unknown | int | (Divergent(Id(6c07)) & ~AlwaysFalsy) | (Divergent(Id(1c00)) & ~AlwaysFalsy)
3: Unknown | int | (Divergent(Id(1c00)) & ~AlwaysFalsy) | (Divergent(Id(6c07)) & ~AlwaysFalsy)
4: Unknown | int | (Divergent(Id(6c07)) & ~AlwaysFalsy) | (Divergent(Id(1c00)) & ~AlwaysFalsy)
...
```
The problem is that the order of union types is not stable between
cycles. To solve this, when unioning the previous union type with the
current union type, we should use the previous type as the base and add
only the new elements in this cycle (In the current implementation, this
unioning order was reversed).
## Test Plan
New corpus test
## Summary
IIUC, tuples with a known structure (`tuple_spec`) use the standard
tuple `__eq__` which only returns `True` for other tuples, so they can
be safely excluded when disjoint from string literals or other non-tuple
types.
Closes https://github.com/astral-sh/ty/issues/2140.
## Summary
The following snippet currently errors because we widen the inferred
type, even though `X` is covariant over `T`. If `T` was contravariant or
invariant, this would be fine, as it would lead to an assignability
error anyways.
```python
class X[T]:
def __init__(self: X[None]): ...
def pop(self) -> T:
raise NotImplementedError
# error: Argument to bound method `__init__` is incorrect: Expected `X[None]`, found `X[int | None]`
x: X[int | None] = X()
```
There are some cases where it is still helpful to prefer covariant
declared types, but this error seems hard to fix otherwise, and makes
our heuristics more consistent overall.
## Summary
This PR implements the strategy described in
https://github.com/astral-sh/ty/issues/1871: we iterate over the
positive types, resolve them, then intersect the results.
## Summary
This should make revealed types a little nicer, as well as avoid
confusing the constraint solver in some cases (which were showing up in
https://github.com/astral-sh/ruff/pull/21930).
## Summary
Add lockfiles for all mdtests which make use of external dependencies.
When running tests normally, we use this lockfile when creating the
temporary venv using `uv sync --locked`. A new
`MDTEST_UPGRADE_LOCKFILES` environment variable is used to switch to a
mode in which those lockfiles can be updated or regenerated. When using
the Python mdtest runner, this environment variable is automatically set
(because we use this command while developing, not to simulate exactly
what happens in CI). A command-line flag is provided to opt out of this.
## Test Plan
### Using the mdtest runner
#### Adding a new test (no lockfile yet)
* Removed `attrs.lock` to simulate this
* Ran `uv run crates/ty_python_semantic/mdtest.py -e external/`. The
lockfile is generated and the test succeeds.
#### Upgrading/downgrading a dependency
* Changed pydantic requirement from `pydantic==2.12.2` to
`pydantic==2.12.5` (also tested with `2.12.0`)
* Ran `uv run crates/ty_python_semantic/mdtest.py -e external/`. The
lockfile is updated and the test succeeds.
### Using cargo
#### Adding a new test (no lockfile yet)
* Removed `attrs.lock` to simulate this
* Ran `MDTEST_EXTERNAL=1 cargo test -p ty_python_semantic --test mdtest
mdtest__external` "naively", which outputs:
> Failed to setup in-memory virtual environment with dependencies:
Lockfile not found at
'/home/shark/ruff/crates/ty_python_semantic/resources/mdtest/external/attrs.lock'.
Run with `MDTEST_UPGRADE_LOCKFILES=1` to generate it.
* Ran `MDTEST_UPGRADE_LOCKFILES=1 MDTEST_EXTERNAL=1 cargo test -p
ty_python_semantic --test mdtest mdtest__external`. The lockfile is
updated and the test succeeds.
#### Upgrading/downgrading a dependency
* Changed pydantic requirement from `pydantic==2.12.2` to
`pydantic==2.12.5` (also tested with `2.12.0`)
* Ran `MDTEST_EXTERNAL=1 cargo test -p ty_python_semantic --test mdtest
mdtest__external` "naively", which outputs a similar error message as
above.
* Ran the command suggested in the error message (`MDTEST_EXTERNAL=1
MDTEST_UPGRADE_LOCKFILES=1 cargo test -p ty_python_semantic --test
mdtest mdtest__external`). The lockfile is updated and the test
succeeds.
When inferring a specialization of a `Callable` type, we use the new
constraint set implementation. In the example in
https://github.com/astral-sh/ty/issues/1968, we end up with a constraint
set that includes all of the following clauses:
```
U_co ≤ M1 | M2 | M3 | M4 | M5 | M6 | M7
M1 ≤ U_co ≤ M1 | M2 | M3 | M4 | M5 | M6 | M7
M2 ≤ U_co ≤ M1 | M2 | M3 | M4 | M5 | M6 | M7
M3 ≤ U_co ≤ M1 | M2 | M3 | M4 | M5 | M6 | M7
M4 ≤ U_co ≤ M1 | M2 | M3 | M4 | M5 | M6 | M7
M5 ≤ U_co ≤ M1 | M2 | M3 | M4 | M5 | M6 | M7
M6 ≤ U_co ≤ M1 | M2 | M3 | M4 | M5 | M6 | M7
M7 ≤ U_co ≤ M1 | M2 | M3 | M4 | M5 | M6 | M7
```
In general, we take the upper bounds of those constraints to get the
specialization. However, the upper bounds of those constraints are not
all guaranteed to be the same, and so first we need to intersect them
all together. In this case, the upper bounds are all identical, so their
intersection is trivial:
```
U_co = M1 | M2 | M3 | M4 | M5 | M6 | M7
```
But we were still doing the work of calculating that trivial
intersection 7 times. And each time we have to do 7^2 comparisons of the
`M*` classes, ending up with O(n^3) overall work.
This pattern is common enough that we can put in a quick heuristic to
prune identical copies of the same type before performing the
intersection.
Fixes https://github.com/astral-sh/ty/issues/1968
## Summary
This contains two bug fixes:
- [Handle field specifier functions that accept
`**kwargs`](ad6918d505)
- [Recognize metaclass-based transformers as instances of
`DataclassInstance`](1a8e29b23c)
closes https://github.com/astral-sh/ty/issues/1987
## Test Plan
* New Markdown tests
* Made sure that the example in 1987 checks without errors
## Summary
We're actually quite good at computing this but the main issue is just
that we compute it at the type-level and so wrap it in `Literal[...]`.
So just special-case the rendering of these to omit `Literal[...]` and
fallback to `...` in cases where the thing we'll show is probably
useless (i.e. `x: str = str`).
Fixes https://github.com/astral-sh/ty/issues/1882
This fixes a bug @zsol found running ty against pyx. His original repro
is:
```py
class Base:
def __init__(self) -> None: pass
class A(Base):
pass
def foo[T](callable: Callable[..., T]) -> T:
return callable()
a: A = foo(A)
```
The call at the bottom would fail, since we would infer `() -> Base` as
the callable type of `A`, when it should be `() -> A`.
The issue was how we add implicit annotations to `self` parameters.
Typically, we turn it into `self: Self`. But in cases where we don't
need to introduce a full typevar, we turn it into `self: [the class
itself]` — in this case, `self: Base`. Then, when turning the class
constructor into a callable, we would see this non-`Self` annotation and
think that it was important and load-bearing.
The fix is that we skip all implicit annotations when determining
whether the `self` annotation should take precedence in the callable's
return type.
This is a first stab at solving
https://github.com/astral-sh/ty/issues/500, at least in part, with the
old solver. We add a new `TypeRelation` that lets us opt into using
constraint sets to describe when a typevar is assignability to some
type, and then use that to calculate a constraint set that describes
when two callable types are assignable. If the callable types contain
typevars, that constraint set will describe their valid specializations.
We can then walk through all of the ways the constraint set can be
satisfied, and record a type mapping in the old solver for each one.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
Co-authored-by: Alex Waygood <alex.waygood@gmail.com>
Fixes https://github.com/astral-sh/ty/issues/1787
## Summary
Allow method decorators returning Callables to presumptively propagate
"classmethod-ness" in the same way that they already presumptively
propagate "function-like-ness". We can't actually be sure that this is
the case, based on the decorator's annotations, but (along with other
type checkers) we heuristically assume it to be the case for decorators
applied via decorator syntax.
## Test Plan
Added mdtest.
## Summary
Infer `Literal[True]` for `isinstance(x, C)` calls when `x: T` and `T`
has a bound `B` that satisfies the `isinstance` check against `C`.
Similar for constrained typevars.
closes https://github.com/astral-sh/ty/issues/1895
## Test Plan
* New Markdown tests
* Verified the the example in the linked ticket checks without errors
When we calculate which typevars are inferable in a generic context, the
result might include more than the typevars bound by the generic
context. The canonical example is a generic method of a generic class:
```py
class C[A]:
def method[T](self, t: T): ...
```
Here, the inferable typevar set of `method` contains `Self` and `T`, as
you'd expect. (Those are the typevars bound by the method.) But it also
contains `A@C`, since the implicit `Self` typevar is defined as `Self:
C[A]`. That means when we call `method`, we need to mark `A@C` as
inferable, so that we can determine the correct mapping for `A@C` at the
call site.
Fixes https://github.com/astral-sh/ty/issues/1874
## Summary
- Treat `if TYPE_CHECKING` blocks the same as stub files (the feature
requested in https://github.com/astral-sh/ty/issues/1216)
- We currently only allow `@abstractmethod`-decorated methods to omit
the implementation if they're methods in classes that have _exactly_
`ABCMeta` as their metaclass. That seems wrong -- `@abstractmethod` has
the same semantics if a class has a subclass of `ABCMeta` as its
metaclass. This PR fixes that too. (I'm actually not _totally_ sure we
should care what the class's metaclass is at all -- see discussion in
https://github.com/astral-sh/ty/issues/1877#issue-3725937441... but the
change this PR is making seems less wrong than what we have currently,
anyway.)
Fixes https://github.com/astral-sh/ty/issues/1216
## Test Plan
Mdtests and snapshots
We now allow the lower and upper bounds of a constraint to be gradual.
Before, we would take the top/bottom materializations of the bounds.
This required us to pass in whether the constraint was intended for a
subtyping check or an assignability check, since that would control
whether we took the "restrictive" or "permissive" materializations,
respectively.
Unfortunately, doing so means that we lost information about whether the
original query involves a non-fully-static type. This would cause us to
create specializations like `T = object` for the constraint `T ≤ Any`,
when it would be nicer to carry through the gradual type and produce `T
= Any`.
We're not currently using constraint sets for subtyping checks, nor are
we going to in the very near future. So for now, we're going to assume
that constraint sets are always used for assignability checks, and allow
the lower/upper bounds to not be fully static. Once we get to the point
where we need to use constraint sets for subtyping checks, we will
consider how best to record this information in constraints.
## Summary
This PR makes explicit specialization of a type variable itself an
error, and the result of the specialization is `Unknown`.
The change also fixes https://github.com/astral-sh/ty/issues/1794.
## Test Plan
mdtests updated
new corpus test
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
This PR takes the improvements we made to unsupported-comparison
diagnostics in https://github.com/astral-sh/ruff/pull/21737, and extends
them to other `unsupported-operator` diagnostics.
## Test Plan
Mdtests and snapshots
## Summary
Working on py-fuzzer recently (AKA, a Python project!) reminded me how
cool our "inlay hint goto-definition feature" is. So this PR adds a
bunch more of that!
I also made a couple of other minor changes to type display. For
example, in the playground, this snippet:
```py
def f(): ...
reveal_type(f.__get__)
```
currently leads to this diagnostic:
```
Revealed type: `<method-wrapper `__get__` of `f`>` (revealed-type) [Ln 2, Col 13]
```
But the fact that we have backticks both around the type display and
inside the type display isn't _great_ there. This PR changes it to
```
Revealed type: `<method-wrapper '__get__' of function 'f'>` (revealed-type) [Ln 2, Col 13]
```
which avoids the nested-backticks issue in diagnostics, and is more
similar to our display for various other `Type` variants such as
class-literal types (`<class 'Foo'>`, etc., not ``<class `Foo`>``).
## Test Plan
inlay snapshots added; mdtests updated
By teaching desperate resolution to try every possible ancestor that
doesn't have an `__init__.py(i)` when resolving absolute imports.
* Fixes https://github.com/astral-sh/ty/issues/1782
