Closes#11216
Essentially the approach is to implement `Format` for a new struct
`FormatClause` which is just a clause header _and_ its body. We then
have the information we need to see whether there is a skip suppression
comment on the last child in the body and it all fits on one line.
This saga began with a regression in how we handle constraint sets where
a typevar is constrained by another typevar, which #21068 first added
support for:
```py
def mutually_constrained[T, U]():
# If [T = U ∧ U ≤ int], then [T ≤ int] must be true as well.
given_int = ConstraintSet.range(U, T, U) & ConstraintSet.range(Never, U, int)
static_assert(given_int.implies_subtype_of(T, int))
```
While working on #21414, I saw a regression in this test, which was
strange, since that PR has nothing to do with this logic! The issue is
that something in that PR made us instantiate the typevars `T` and `U`
in a different order, giving them differently ordered salsa IDs. And
importantly, we use these salsa IDs to define the variable ordering that
is used in our constraint set BDDs. This showed that our "mutually
constrained" logic only worked for one of the two possible orderings.
(We can — and now do — test this in a brute-force way by copy/pasting
the test with both typevar orderings.)
The underlying bug was in our `ConstraintSet::simplify_and_domain`
method. It would correctly detect `(U ≤ T ≤ U) ∧ (U ≤ int)`, because
those two constraints affect different typevars, and from that, infer `T
≤ int`. But it wouldn't detect the equivalent pattern in `(T ≤ U ≤ T) ∧
(U ≤ int)`, since those constraints affect the same typevar. At first I
tried adding that as yet more pattern-match logic in the ever-growing
`simplify_and_domain` method. But doing so caused other tests to start
failing.
At that point, I realized that `simplify_and_domain` had gotten to the
point where it was trying to do too much, and for conflicting consumers.
It was first written as part of our display logic, where the goal is to
remove redundant information from a BDD to make its string rendering
simpler. But we also started using it to add "derived facts" to a BDD. A
derived fact is a constraint that doesn't appear in the BDD directly,
but which we can still infer to be true. Our failing test relies on
derived facts — being able to infer that `T ≤ int` even though that
particular constraint doesn't appear in the original BDD. Before,
`simplify_and_domain` would trace through all of the constraints in a
BDD, figure out the full set of derived facts, and _add those derived
facts_ to the BDD structure. This is brittle, because those derived
facts are not universally true! In our example, `T ≤ int` only holds
along the BDD paths where both `T = U` and `U ≤ int`. Other paths will
test the negations of those constraints, and on those, we _shouldn't_
infer `T ≤ int`. In theory it's possible (and we were trying) to use BDD
operators to express that dependency...but that runs afoul of how we
were simultaneously trying to _remove_ information to make our displays
simpler.
So, I ripped off the band-aid. `simplify_and_domain` is now _only_ used
for display purposes. I have not touched it at all, except to remove
some logic that is definitely not used by our `Display` impl. Otherwise,
I did not want to touch that house of cards for now, since the display
logic is not load-bearing for any type inference logic.
For all non-display callers, we have a new **_sequent map_** data type,
which tracks exactly the same derived information. But it does so (a)
without trying to remove anything from the BDD, and (b) lazily, without
updating the BDD structure.
So the end result is that all of the tests (including the new
regressions) pass, via a more efficient (and hopefully better
structured/documented) implementation, at the cost of hanging onto a
pile of display-related tech debt that we'll want to clean up at some
point.
## Summary
This is another attempt at https://github.com/astral-sh/ruff/pull/21410
that fixes https://github.com/astral-sh/ruff/issues/19226.
@MichaReiser helped me get something working in a very helpful pairing
session. I pushed one additional commit moving the comments back from
leading comments to trailing comments, which I think retains more of the
input formatting.
I was inspired by Dylan's PR (#21185) to make one of these tables:
<table>
<thead>
<tr>
<th scope="col">Input</th>
<th scope="col">Main</th>
<th scope="col">PR</th>
</tr>
</thead>
<tbody>
<tr>
<td><pre lang="python">
if (
not
# comment
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa +
bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
):
pass
</pre></td>
<td><pre lang="python">
if (
# comment
not aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+ bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
):
pass
</pre></td>
<td><pre lang="python">
if (
not
# comment
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+ bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
):
pass
</pre></td>
</tr>
<tr>
<td><pre lang="python">
if (
# unary comment
not
# operand comment
(
# comment
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+ bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
)
):
pass
</pre></td>
<td><pre lang="python">
if (
# unary comment
# operand comment
not (
# comment
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+ bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
)
):
pass
</pre></td>
<td><pre lang="python">
if (
# unary comment
not
# operand comment
(
# comment
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+ bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
)
):
pass
</pre></td>
</tr>
<tr>
<td><pre lang="python">
if (
not # comment
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+ bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
):
pass
</pre></td>
<td><pre lang="python">
if ( # comment
not aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+ bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
):
pass
</pre></td>
<td><pre lang="python">
if (
not aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa # comment
+ bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
):
pass
</pre></td>
</tr>
</tbody>
</table>
hopefully it helps even though the snippets are much wider here.
The two main differences are (1) that we now retain own-line comments
between the unary operator and its operand instead of moving these to
leading comments on the operator itself, and (2) that we move
end-of-line comments between the operator and operand to dangling
end-of-line comments on the operand (the last example in the table).
## Test Plan
Existing tests, plus new ones based on the issue. As I noted below, I
also ran the output from main on the unary.py file back through this
branch to check that we don't reformat code from main. This made me feel
a bit better about not preview-gating the changes in this PR.
```shell
> git show main:crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/unary.py | ruff format - | ./target/debug/ruff format --diff -
> echo $?
0
```
---------
Co-authored-by: Micha Reiser <micha@reiser.io>
Co-authored-by: Takayuki Maeda <takoyaki0316@gmail.com>
## Summary
This PR proposes that we add a new `set_concise_message` functionality
to our `Diagnostic` construction API. When used, the concise message
that is otherwise auto-generated from the main diagnostic message and
the primary annotation will be overwritten with the custom message.
To understand why this is desirable, let's look at the `invalid-key`
diagnostic. This is how I *want* the full diagnostic to look like:
<img width="620" height="282" alt="image"
src="https://github.com/user-attachments/assets/3bf70f52-9d9f-4817-bc16-fb0ebf7c2113"
/>
However, without the change in this PR, the concise message would have
the following form:
```
error[invalid-key]: Unknown key "Age" for TypedDict `Person`: Unknown key "Age" - did you mean "age"?
```
This duplication is why the full `invalid-key` diagnostic used a main
diagnostic message that is only "Invalid key for TypedDict `Person`", to
make that bearable:
```
error[invalid-key] Invalid key for TypedDict `Person`: Unknown key "Age" - did you mean "age"?
```
This is still less than ideal, *and* we had to make the "full"
diagnostic worse. With the new API here, we have to make no such
compromises. We need to do slightly more work (provide one additional
custom-designed message), but we get to keep the "full" diagnostic that
we actually want, and we can make the concise message more terse and
readable:
```
error[invalid-key] Unknown key "Age" for TypedDict `Person` - did you mean "age"?
```
Similar problems exist for other diagnostics as well (I really want this
for https://github.com/astral-sh/ruff/pull/21476). In this PR, I only
changed `invalid-key` and `type-assertion-failure`.
The PR here is somewhat related to the discussion in
https://github.com/astral-sh/ty/issues/1418, but note that we are
solving a problem that is unrelated to sub-diagnostics.
## Test Plan
Updated tests
## Summary
Add support for `Callable` special forms in implicit type aliases.
## Typing conformance
Four new tests are passing
## Ecosystem impact
* All of the `invalid-type-form` errors are from libraries that use
`mypy_extensions` and do something like `Callable[[NamedArg("x", str)],
int]`.
* A handful of new false positives because we do not support generic
specializations of implicit type aliases, yet. But other
* Everything else looks like true positives or known limitations
## Test Plan
New Markdown tests.
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Fixes#21389
Avoid RUF012 false positives when reassigning a ClassVar
## Test Plan
<!-- How was it tested? -->
Added the new reassignment scenario to
`crates/ruff_linter/resources/test/fixtures/ruff/RUF012.py`.
---------
Co-authored-by: Brent Westbrook <brentrwestbrook@gmail.com>
Constraint sets can now track subtyping/assignability/etc of generic
callables correctly. For instance:
```py
def identity[T](t: T) -> T:
return t
constraints = ConstraintSet.always()
static_assert(constraints.implies_subtype_of(TypeOf[identity], Callable[[int], int]))
static_assert(constraints.implies_subtype_of(TypeOf[identity], Callable[[str], str]))
```
A generic callable can be considered an intersection of all of its
possible specializations, and an assignability check with an
intersection as the lhs side succeeds of _any_ of the intersected types
satisfies the check. Put another way, if someone expects to receive any
function with a signature of `(int) -> int`, we can give them
`identity`.
Note that the corresponding check using `is_subtype_of` directly does
not yet work, since #20093 has not yet hooked up the core typing
relationship logic to use constraint sets:
```py
# These currently fail
static_assert(is_subtype_of(TypeOf[identity], Callable[[int], int]))
static_assert(is_subtype_of(TypeOf[identity], Callable[[str], str]))
```
To do this, we add a new _existential quantification_ operation on
constraint sets. This takes in a list of typevars and _removes_ those
typevars from the constraint set. Conceptually, we return a new
constraint set that evaluates to `true` when there was _any_ assignment
of the removed typevars that caused the old constraint set to evaluate
to `true`.
When comparing a generic constraint set, we add its typevars to the
`inferable` set, and figure out whatever constraints would allow any
specialization to satisfy the check. We then use the new existential
quantification operator to remove those new typevars, since the caller
doesn't (and shouldn't) know anything about them.
---------
Co-authored-by: David Peter <sharkdp@users.noreply.github.com>
Closes#19350
This fixes a syntax error caused by formatting. However, the new tests reveal that there are some cases where formatting attributes with certain comments behaves strangely, both before and after this PR, so some more polish may be in order.
For example, without parentheses around the value, and both before and after this PR, we have:
```python
# unformatted
variable = (
something # a comment
.first_method("some string")
)
# formatted
variable = something.first_method("some string") # a comment
```
which is probably not where the comment ought to go.
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Partially addresses https://github.com/astral-sh/ty/issues/1562
Only suggest the keyword "as" in import statements when the user have
written `import foo a<CURSOR>` or `from foo import bar a<CURSOR>` as no
other suggestion makes sense here.
Re-uses the existing pattern for incomplete `import from` statements to
determine incomplete import alias statements and make the suggestions
more sane in those cases.
There was a potential suggestion from @BurntSushi in
https://github.com/astral-sh/ty/issues/1562#issue-3626853513 to move the
handling of import statements into one unified state machine but I acted
on the side of caution and fixed this with already established patterns,
pending a potential bigger re-write down the line.
## Test Plan
Added new tests and checked that it behaved reasonable in the
playground.
<!-- How was it tested? -->
This PR attempts to improve the placement of own-line comments between
branches in the setting where the comment is more indented than the
preceding node.
There are two main changes.
### First change: Preceding node has leading content
If the preceding node has leading content, we now regard the comment as
automatically _less_ indented than the preceding node, and format
accordingly.
For example,
```python
if True: preceding_node
# leading on `else`, not trailing on `preceding_node`
else: ...
```
This is more compatible with `black`, although there is a (presumably
very uncommon) edge case:
```python
if True:
this;that
# leading on `else`, but trailing in `black`
else: ...
```
I'm sort of okay with this - presumably if one wanted a comment for
those semi-colon separated statements, one should have put it _above_
them, and one wanted a comment only for `that` then it ought to have
been on the same line?
### Second change: searching for last child in body
While searching for the (recursively) last child in the body of the
preceding _branch_, we implicitly assumed that the preceding node had to
have a body to begin the recursion. But actually, in the base case, the
preceding node _is_ the last child in the body of the preceding branch.
So, for example:
```python
if True:
something
last_child_but_no_body
# leading on else for `main` but trailing in this PR
else: ...
```
### More examples
The table below is an attempt to summarize the changes in behavior. The
rows alternate between an example snippet with `while` and the same
example with `if` - in the former case we do _not_ have an `else` node
and in the latter we do.
Notice that:
1. On `main` our handling of `if` vs. `while` is not consistent, whereas
it is consistent in the present PR
2. We disagree with `black` in all cases except that last example on
`main`, but agree in all cases for the present PR (though see above for
a wonky edge case where we disagree).
<table>
<tr>
<th>Original
</th>
<th><code>main</code> </th>
<th>This
PR </th>
<th><code>black</code> </th>
</tr>
<tr>
<td>
<pre lang="python">
while True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
while True:
pass
else:
# comment
pass
</pre>
</td>
<td>
<pre lang="python">
while True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
while True:
pass
# comment
else:
pass
</pre>
</td>
</tr>
<tr>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
</tr>
<tr>
<td>
<pre lang="python">
while True: pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
while True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
while True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
while True:
pass
# comment
else:
pass
</pre>
</td>
</tr>
<tr>
<td>
<pre lang="python">
if True: pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
</tr>
<tr>
<td>
<pre lang="python">
while True: pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
while True:
pass
else:
# comment
pass
</pre>
</td>
<td>
<pre lang="python">
while True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
while True:
pass
# comment
else:
pass
</pre>
</td>
</tr>
<tr>
<td>
<pre lang="python">
if True: pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
<td>
<pre lang="python">
if True:
pass
# comment
else:
pass
</pre>
</td>
</tr>
</table>
## Summary
Follow up from https://github.com/astral-sh/ruff/pull/21411. Again,
there are more things that could be improved here (like the diagnostics
for `lists`, or extending what we have for `dict` to `OrderedDict` etc),
but that will have to be postponed.
## Summary
We previously only allowed models to overwrite the
`{eq,order,kw_only,frozen}_defaults` of the dataclass-transformer, but
all other standard-dataclass parameters should be equally supported with
the same behavior.
## Test Plan
Added regression tests.
## Summary
Not a high-priority task... but it _is_ a weekend :P
This PR improves our diagnostics for invalid exceptions. Specifically:
- We now give a special-cased ``help: Did you mean
`NotImplementedError`` subdiagnostic for `except NotImplemented`, `raise
NotImplemented` and `raise <EXCEPTION> from NotImplemented`
- If the user catches a tuple of exceptions (`except (foo, bar, baz):`)
and multiple elements in the tuple are invalid, we now collect these
into a single diagnostic rather than emitting a separate diagnostic for
each tuple element
- The explanation of why the `except`/`raise` was invalid ("must be a
`BaseException` instance or `BaseException` subclass", etc.) is
relegated to a subdiagnostic. This makes the top-level diagnostic
summary much more concise.
## Test Plan
Lots of snapshots. And here's some screenshots:
<details>
<summary>Screenshots</summary>
<img width="1770" height="1520" alt="image"
src="https://github.com/user-attachments/assets/7f27fd61-c74d-4ddf-ad97-ea4fd24d06fd"
/>
<img width="1916" height="1392" alt="image"
src="https://github.com/user-attachments/assets/83e5027c-8798-48a6-a0ec-1babfc134000"
/>
<img width="1696" height="588" alt="image"
src="https://github.com/user-attachments/assets/1bc16048-6eb4-4dfa-9ace-dd271074530f"
/>
</details>
## Summary
Allow metaclass-based and baseclass-based dataclass-transformers to
overwrite the default behavior using class arguments:
```py
class Person(Model, order=True):
# ...
```
## Conformance tests
Four new tests passing!
## Test Plan
New Markdown tests
This PR updates the constraint implication type relationship to work on
compound types as well. (A compound type is a non-atomic type, like
`list[T]`.)
The goal of constraint implication is to check whether the requirements
of a constraint imply that a particular subtyping relationship holds.
Before, we were only checking atomic typevars. That would let us verify
that the constraint set `T ≤ bool` implies that `T` is always a subtype
of `int`. (In this case, the lhs of the subtyping check, `T`, is an
atomic typevar.)
But we weren't recursing into compound types, to look for nested
occurrences of typevars. That means that we weren't able to see that `T
≤ bool` implies that `Covariant[T]` is always a subtype of
`Covariant[int]`.
Doing this recursion means that we have to carry the constraint set
along with us as we recurse into types as part of `has_relation_to`, by
adding constraint implication as a new `TypeRelation` variant. (Before
it was just a method on `ConstraintSet`.)
---------
Co-authored-by: David Peter <sharkdp@users.noreply.github.com>
## Summary
Currently our diagnostic only covers the range of the thing being
subscripted:
<img width="1702" height="312" alt="image"
src="https://github.com/user-attachments/assets/7e630431-e846-46ca-93c1-139f11aaba11"
/>
But it should probably cover the _whole_ subscript expression (arguably
the more "incorrect" bit is the `["foo"]` part of this expression, not
the `x` part of this expression!)
## Test Plan
Added a snapshot
Co-authored-by: Brent Westbrook
<36778786+ntBre@users.noreply.github.com>
## Summary
Extends literal promotion to apply to any generic method, as opposed to
only generic class constructors. This PR also improves our literal
promotion heuristics to only promote literals in non-covariant position
in the return type, and avoid promotion if the literal is present in
non-covariant position in any argument type.
Resolves https://github.com/astral-sh/ty/issues/1357.
## Summary
- Always restore the previous `deferred_state` after parsing a type
expression: we don't want that state leaking out into other contexts
where we shouldn't be deferring expression inference
- Always defer the right-hand-side of a PEP-613 type alias in a stub
file, allowing for forward references on the right-hand side of `T:
TypeAlias = X | Y` in a stub file
Addresses @carljm's review in
https://github.com/astral-sh/ruff/pull/21401#discussion_r2524260153
## Test Plan
I added a regression test for a regression that the first version of
this PR introduced (we need to make sure the r.h.s. of a PEP-613
`TypeAlias`es is always deferred in a stub file)
## Summary
We currently fail to account for the type context when inferring generic
classes constructed with `__new__`, or synthesized `__init__` for
dataclasses.
There are a few places in Python where it is known that new names are
being introduced and thus we probably shouldn't offer completions. We
already handle this today for things like `class <CURSOR>` and `def
<CURSOR>`. But we didn't handle `as <CURSOR>`, which can appear in
`import`, `with`, `except` and `match` statements. Indeed, these are
exactly the 4 cases where the `as` keyword can occur. So we look for the
presence of `as` and suppress completions based on that.
While we're here, we also make the implementation a bit more robust with
respect to suppressing completions when the user hasn't typed anything.
Namely, previously, we'd still offer completions in a `class <CURSOR>`
context. But it looks like LSP clients (at least, VS Code) doesn't ask
for completions here, so we were "saved" incidentally. This PR detects
this case and suppresses completions there so we don't rely on LSP
client behavior to handle that case correctly.
Fixesastral-sh/ty#1287
## Summary
Infer the first argument `type` inside `Annotated[type, …]` as a type
expression. This allows us to support stringified annotations inside
`Annotated`.
## Ecosystem
* The removed diagnostic on `prefect` shows that we now understand the
`State.data` type annotation in
`src/prefect/client/schemas/objects.py:230`, which uses a stringified
annotation in `Annoated`. The other diagnostics are downstream changes
that result from this, it seems to be a commonly used data type.
* `artigraph` does something like `Annotated[cast(Any,
field_info.annotation), *field_info.metadata]` which I'm not sure we
need to allow? It's unfortunate since this is probably supported at
runtime, but it seems reasonable that they need to add a `# type:
ignore` for that.
* `pydantic` uses something like `Annotated[(self.annotation,
*self.metadata)]` but adds a `# type: ignore`
## Test Plan
New Markdown test
## Summary
Typeshed has a (fake) `__getattr__` method on `types.ModuleType` with a
return type of `Any`. We ignore this method when accessing attributes on
module *literals*, but with this PR, we respect this method when dealing
with `ModuleType` itself. That is, we allow arbitrary attribute accesses
on instances of `types.ModuleType`. This is useful because dynamic
import mechanisms such as `importlib.import_module` use `ModuleType` as
a return type.
closes https://github.com/astral-sh/ty/issues/1346
## Ecosystem
Massive reduction in diagnostics. The few new diagnostics are true
positives.
## Test Plan
Added regression test.
## Summary
Add synthetic members to completions on dataclasses and dataclass
instances.
Also, while we're at it, add support for `__weakref__` and
`__match_args__`.
closes https://github.com/astral-sh/ty/issues/1542
## Test Plan
New Markdown tests
## Summary
Support various legacy `typing` special forms (`List`, `Dict`, …) in
implicit type aliases.
## Ecosystem impact
A lot of true positives (e.g. on `alerta`)!
## Test Plan
New Markdown tests
## Summary
Support `type[…]` in implicit type aliases, for example:
```py
SubclassOfInt = type[int]
reveal_type(SubclassOfInt) # GenericAlias
def _(subclass_of_int: SubclassOfInt):
reveal_type(subclass_of_int) # type[int]
```
part of https://github.com/astral-sh/ty/issues/221
## Typing conformance
```diff
-specialtypes_type.py:138:5: error[type-assertion-failure] Argument does not have asserted type `type[Any]`
-specialtypes_type.py:140:5: error[type-assertion-failure] Argument does not have asserted type `type[Any]`
```
Two new tests passing ✔️
```diff
-specialtypes_type.py:146:1: error[unresolved-attribute] Object of type `GenericAlias` has no attribute `unknown`
```
An `TA4.unknown` attribute on a PEP 613 alias (`TA4: TypeAlias =
type[Any]`) is being accessed, and the conformance suite expects this to
be an error. Since we currently use the inferred type for these type
aliases (and possibly in the future as well), we treat this as a direct
access of the attribute on `type[Any]`, which falls back to an access on
`Any` itself, which succeeds. 🔴
```
+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
```
New errors because we don't handle `T = TypeVar("T"); MyType = type[T];
MyType[T]` yet. Support for this is being tracked in
https://github.com/astral-sh/ty/issues/221🔴
## Ecosystem impact
Looks mostly good, a few known problems.
## Test Plan
New Markdown tests
## Summary
Allow users of `mdtest.py` to press enter to rerun all mdtests without
recompiling (thanks @AlexWaygood).
I swear I tried three other approaches (including a fully async version)
before I settled on this solution. It is indeed silly, but works just
fine.
## Test Plan
Interactive playing around
## Summary
Further improve subscript assignment diagnostics, especially for
`dict`s:
```py
config: dict[str, int] = {}
config["retries"] = "three"
```
<img width="1276" height="274" alt="image"
src="https://github.com/user-attachments/assets/9762c733-8d1c-4a57-8c8a-99825071dc7d"
/>
I have many more ideas, but this looks like a reasonable first step.
Thank you @AlexWaygood for some of the suggestions here.
## Test Plan
Update tests
