## Summary
Closes https://github.com/astral-sh/ruff/issues/15508
For any two instance types `T` and `S`, we know they are disjoint if
either `T` is final and `T` is not a subclass of `S` or `S` is final and
`S` is not a subclass of `T`.
Correspondingly, for any two types `type[T]` and `S` where `S` is an
instance type, `type[T]` can be said to be disjoint from `S` if `S` is
disjoint from `U`, where `U` is the type that represents all instances
of `T`'s metaclass.
And a heterogeneous tuple type can be said to be disjoint from an
instance type if the instance type is disjoint from `tuple` (a type
representing all instances of the `tuple` class at runtime).
## Test Plan
- A new mdtest added. Most of our `is_disjoint_from()` tests are not
written as mdtests just yet, but it's pretty hard to test some of these
edge cases from a Rust unit test!
- Ran `QUICKCHECK_TESTS=1000000 cargo test --release -p
red_knot_python_semantic -- --ignored types::property_tests::stable`
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
This implements checking of calls.
I ended up following Micha's original suggestion from back when the
signature representation was first introduced, and flattening it to a
single array of parameters. This turned out to be easier to manage,
because we can represent parameters using indices into that array, and
represent the bound argument types as an array of the same length.
Starred and double-starred arguments are still TODO; these won't be very
useful until we have generics.
The handling of diagnostics is just hacked into `return_ty_result`,
which was already inconsistent about whether it emitted diagnostics or
not; now it's even more inconsistent. This needs to be addressed, but
could be a follow-up.
The new benchmark errors here surface the need for intersection support
in `is_assignable_to`.
Fixes#14161.
## Test Plan
Added mdtests.
## Summary
Add support for type narrowing in elif and else scopes as part of
#13694.
## Test Plan
- mdtest
- builder unit test for union negation.
---------
Co-authored-by: Carl Meyer <carl@astral.sh>
## Summary
Add type narrowing for `isinstance(object, classinfo)` [1] checks:
```py
x = 1 if flag else "a"
if isinstance(x, int):
reveal_type(x) # revealed: Literal[1]
```
closes#13893
[1] https://docs.python.org/3/library/functions.html#isinstance
## Test Plan
New Markdown-based tests in `narrow/isinstance.md`.
---------
Co-authored-by: Alex Waygood <Alex.Waygood@Gmail.com>
