[ty] Add failing tests for tuple subclasses (#19803)

crates/ty_python_semantic/resources/mdtest/call/function.md

@@ -164,6 +164,101 @@ def _(args: tuple[int, str]) -> None:
     takes_at_least_two_positional_only(*args)  # error: [invalid-argument-type]
 ```
 
+### Subclass of fixed-length tuple argument
+
+```py
+def takes_zero() -> None: ...
+def takes_one(x: int) -> None: ...
+def takes_two(x: int, y: int) -> None: ...
+def takes_two_positional_only(x: int, y: int, /) -> None: ...
+def takes_two_different(x: int, y: str) -> None: ...
+def takes_two_different_positional_only(x: int, y: str, /) -> None: ...
+def takes_at_least_zero(*args) -> None: ...
+def takes_at_least_one(x: int, *args) -> None: ...
+def takes_at_least_two(x: int, y: int, *args) -> None: ...
+def takes_at_least_two_positional_only(x: int, y: int, /, *args) -> None: ...
+
+# Test all of the above with a number of different splatted argument types
+
+class SingleElementTuple(tuple[int]): ...
+
+def _(args: SingleElementTuple) -> None:
+    # TODO: we should emit `[too-many-positional-arguments]` here
+    takes_zero(*args)
+
+    takes_one(*args)
+
+    # TODO: we should emit `[missing-argument]` on both of these
+    takes_two(*args)
+    takes_two_positional_only(*args)
+
+    # TODO: these should both be `[missing-argument]`, not `[invalid-argument-type]`
+    takes_two_different(*args)  # error: [invalid-argument-type]
+    takes_two_different_positional_only(*args)  # error: [invalid-argument-type]
+
+    takes_at_least_zero(*args)
+    takes_at_least_one(*args)
+
+    # TODO: we should emit `[missing-argument]` on both of these
+    takes_at_least_two(*args)
+    takes_at_least_two_positional_only(*args)
+
+class TwoElementIntTuple(tuple[int, int]): ...
+
+def _(args: TwoElementIntTuple) -> None:
+    # TODO: we should emit `[too-many-positional-arguments]` on both of these
+    takes_zero(*args)
+    takes_one(*args)
+
+    takes_two(*args)
+    takes_two_positional_only(*args)
+    takes_two_different(*args)  # error: [invalid-argument-type]
+    takes_two_different_positional_only(*args)  # error: [invalid-argument-type]
+    takes_at_least_zero(*args)
+    takes_at_least_one(*args)
+    takes_at_least_two(*args)
+    takes_at_least_two_positional_only(*args)
+
+class IntStrTuple(tuple[int, str]): ...
+
+def _(args: IntStrTuple) -> None:
+    # TODO: we should emit `[too-many-positional-arguments]` here
+    takes_zero(*args)
+
+    # TODO: this should be `[too-many-positional-arguments]`, not `[invalid-argument-type]`
+    takes_one(*args)  # error: [invalid-argument-type]
+
+    # TODO: we should have one diagnostic for each of these, not two
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_positional_only(*args)
+
+    # TODO: these are all false positives
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_different(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_different_positional_only(*args)
+
+    takes_at_least_zero(*args)
+
+    # TODO: false positive
+    # error: [invalid-argument-type]
+    takes_at_least_one(*args)
+
+    # TODO: we should only emit one diagnostic for each of these, not two
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_at_least_two(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_at_least_two_positional_only(*args)
+```
+
 ### Mixed tuple argument
 
 ```toml
@@ -258,6 +353,197 @@ def _(args: tuple[int, *tuple[str, ...], int]) -> None:
     takes_at_least_two_positional_only(*args)  # error: [invalid-argument-type]
 ```
 
+### Subclass of mixed tuple argument
+
+```toml
+[environment]
+python-version = "3.11"
+```
+
+```py
+def takes_zero() -> None: ...
+def takes_one(x: int) -> None: ...
+def takes_two(x: int, y: int) -> None: ...
+def takes_two_positional_only(x: int, y: int, /) -> None: ...
+def takes_two_different(x: int, y: str) -> None: ...
+def takes_two_different_positional_only(x: int, y: str, /) -> None: ...
+def takes_at_least_zero(*args) -> None: ...
+def takes_at_least_one(x: int, *args) -> None: ...
+def takes_at_least_two(x: int, y: int, *args) -> None: ...
+def takes_at_least_two_positional_only(x: int, y: int, /, *args) -> None: ...
+
+# Test all of the above with a number of different splatted argument types
+
+class IntStarInt(tuple[int, *tuple[int, ...]]): ...
+
+def _(args: IntStarInt) -> None:
+    # TODO: we should emit `[too-many-positional-arguments]` here
+    takes_zero(*args)
+
+    takes_one(*args)
+    takes_two(*args)
+    takes_two_positional_only(*args)
+    takes_two_different(*args)  # error: [invalid-argument-type]
+    takes_two_different_positional_only(*args)  # error: [invalid-argument-type]
+    takes_at_least_zero(*args)
+    takes_at_least_one(*args)
+    takes_at_least_two(*args)
+    takes_at_least_two_positional_only(*args)
+
+class IntStarStr(tuple[int, *tuple[str, ...]]): ...
+
+def _(args: IntStarStr) -> None:
+    # TODO: we should emit `[too-many-positional-arguments]` here
+    takes_zero(*args)
+
+    # TODO: false positive
+    # error: [invalid-argument-type]
+    takes_one(*args)
+
+    # TODO: we should only emit one diagnostic for each of these, not two
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_positional_only(*args)
+
+    # TODO: false positives
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_different(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_different_positional_only(*args)
+
+    takes_at_least_zero(*args)
+
+    # TODO: false positive
+    # error: [invalid-argument-type]
+    takes_at_least_one(*args)
+
+    # TODO: we should only have one diagnostic for each of these, not two
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_at_least_two(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_at_least_two_positional_only(*args)
+
+class IntIntStarInt(tuple[int, int, *tuple[int, ...]]): ...
+
+def _(args: IntIntStarInt) -> None:
+    # TODO: we should emit `[too-many-positional-arguments]` on both of these
+    takes_zero(*args)
+    takes_one(*args)
+
+    takes_two(*args)
+    takes_two_positional_only(*args)
+    takes_two_different(*args)  # error: [invalid-argument-type]
+    takes_two_different_positional_only(*args)  # error: [invalid-argument-type]
+    takes_at_least_zero(*args)
+    takes_at_least_one(*args)
+    takes_at_least_two(*args)
+    takes_at_least_two_positional_only(*args)
+
+class IntIntStarStr(tuple[int, int, *tuple[str, ...]]): ...
+
+def _(args: IntIntStarStr) -> None:
+    # TODO: we should emit `[too-many-positional-arguments]` here
+    takes_zero(*args)
+
+    # TODO: this should be `[too-many-positional-arguments]`, not `invalid-argument-type`
+    takes_one(*args)  # error: [invalid-argument-type]
+
+    # TODO: these are all false positives
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_positional_only(*args)
+
+    # TODO: each of these should only have one diagnostic, not two
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_different(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_different_positional_only(*args)
+
+    takes_at_least_zero(*args)
+
+    # TODO: false positive
+    # error: [invalid-argument-type]
+    takes_at_least_one(*args)
+
+    # TODO: these are both false positives
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_at_least_two(*args)
+
+    # TODO: these are both false positives
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_at_least_two_positional_only(*args)
+
+class IntStarIntInt(tuple[int, *tuple[int, ...], int]): ...
+
+def _(args: IntStarIntInt) -> None:
+    # TODO: we should emit `[too-many-positional-arguments]` on both of these
+    takes_zero(*args)
+    takes_one(*args)
+
+    takes_two(*args)
+    takes_two_positional_only(*args)
+    takes_two_different(*args)  # error: [invalid-argument-type]
+    takes_two_different_positional_only(*args)  # error: [invalid-argument-type]
+    takes_at_least_zero(*args)
+    takes_at_least_one(*args)
+    takes_at_least_two(*args)
+    takes_at_least_two_positional_only(*args)
+
+class IntStarStrInt(tuple[int, *tuple[str, ...], int]): ...
+
+def _(args: IntStarStrInt) -> None:
+    # TODO: we should emit `too-many-positional-arguments` here
+    takes_zero(*args)
+
+    # TODO: this should be `too-many-positional-arguments`, not `invalid-argument-type`
+    takes_one(*args)  # error: [invalid-argument-type]
+
+    # TODO: we should only emit one diagnostic for each of these
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_positional_only(*args)
+
+    # TODO: we should not emit diagnostics for these
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_different(*args)
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_two_different_positional_only(*args)
+
+    takes_at_least_zero(*args)
+
+    # TODO: false positive
+    takes_at_least_one(*args)  # error: [invalid-argument-type]
+
+    # TODO: should only have one diagnostic here
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_at_least_two(*args)
+
+    # TODO: should only have one diagnostic here
+    # error: [invalid-argument-type]
+    # error: [invalid-argument-type]
+    takes_at_least_two_positional_only(*args)
+```
+
 ### String argument
 
 ```py

crates/ty_python_semantic/resources/mdtest/generics/legacy/classes.md

@@ -392,6 +392,33 @@ class C(tuple[T, U]): ...
 reveal_type(C((1, 2)))  # revealed: C[int, int]
 ```
 
+### Upcasting a `tuple` to its `Sequence` supertype
+
+This test is taken from the
+[typing spec conformance suite](https://github.com/python/typing/blob/c141cdfb9d7085c1aafa76726c8ce08362837e8b/conformance/tests/tuples_type_compat.py#L133-L153)
+
+```toml
+[environment]
+python-version = "3.11"
+```
+
+```py
+from typing import TypeVar, Sequence, Never
+
+T = TypeVar("T")
+
+def test_seq(x: Sequence[T]) -> Sequence[T]:
+    return x
+
+def func8(t1: tuple[complex, list[int]], t2: tuple[int, *tuple[str, ...]], t3: tuple[()]):
+    # TODO: should be `Sequence[int | float | complex | list[int]]`
+    reveal_type(test_seq(t1))  # revealed: Sequence[Unknown]
+    # TODO: should be `Sequence[int | str]`
+    reveal_type(test_seq(t2))  # revealed: Sequence[Unknown]
+    # TODO: this should be `Sequence[Never]`
+    reveal_type(test_seq(t3))  # revealed: Sequence[Unknown]
+```
+
 ### `__init__` is itself generic
 
 ```py

crates/ty_python_semantic/resources/mdtest/generics/pep695/classes.md

@@ -355,6 +355,26 @@ class C[T, U](tuple[T, U]): ...
 reveal_type(C((1, 2)))  # revealed: C[int, int]
 ```
 
+### Upcasting a `tuple` to its `Sequence` supertype
+
+This test is taken from the
+[typing spec conformance suite](https://github.com/python/typing/blob/c141cdfb9d7085c1aafa76726c8ce08362837e8b/conformance/tests/tuples_type_compat.py#L133-L153)
+
+```py
+from typing import Sequence, Never
+
+def test_seq[T](x: Sequence[T]) -> Sequence[T]:
+    return x
+
+def func8(t1: tuple[complex, list[int]], t2: tuple[int, *tuple[str, ...]], t3: tuple[()]):
+    # TODO: should be `Sequence[int | float | complex | list[int]]`
+    reveal_type(test_seq(t1))  # revealed: Sequence[Unknown]
+    # TODO: should be `Sequence[int | str]`
+    reveal_type(test_seq(t2))  # revealed: Sequence[Unknown]
+    # TODO: this should be `Sequence[Never]`
+    reveal_type(test_seq(t3))  # revealed: Sequence[Unknown]
+```
+
 ### `__init__` is itself generic
 
 ```py

crates/ty_python_semantic/resources/mdtest/subscript/tuple.md

@@ -217,9 +217,89 @@ def _(m: int, n: int):
 
     tuple_slice = t[m:n]
     reveal_type(tuple_slice)  # revealed: tuple[Literal[1, "a", b"b"] | None, ...]
+
+class I0: ...
+class I1: ...
+class I2: ...
+class I3: ...
+class HeterogeneousTupleSubclass(tuple[I0, I1, I2, I3]): ...
+
+def __(t: HeterogeneousTupleSubclass, m: int, n: int):
+    # TODO: should be `tuple[()]`
+    reveal_type(t[0:0])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I0]`
+    reveal_type(t[0:1])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I0, I1]`
+    reveal_type(t[0:2])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be tuple[I0, I1, I2, I3]`
+    reveal_type(t[0:4])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be tuple[I0, I1, I2, I3]`
+    reveal_type(t[0:5])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I0, I1]`
+    reveal_type(t[1:3])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+
+    # TODO: should be `tuple[I2, I3]`
+    reveal_type(t[-2:4])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I1, I2]`
+    reveal_type(t[-3:-1])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I0, I1, I2, I3]`
+    reveal_type(t[-10:10])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+
+    # TODO: should be `tuple[I0, I1, I2, I3]`
+    reveal_type(t[0:])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I2, I3]`
+    reveal_type(t[2:])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[()]`
+    reveal_type(t[4:])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[()]`
+    reveal_type(t[:0])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I0, I1]`
+    reveal_type(t[:2])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I0, I1, I2, I3]`
+    reveal_type(t[:10])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I0, I1, I2, I3]`
+    reveal_type(t[:])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+
+    # TODO: should be `tuple[I3, I2, I1, I0]`
+    reveal_type(t[::-1])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I0, I2]`
+    reveal_type(t[::2])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I2, I1, I0]`
+    reveal_type(t[-2:-5:-1])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I3, I1]`
+    reveal_type(t[::-2])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I3, I0]`
+    reveal_type(t[-1::-3])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+
+    # TODO: should be `tuple[I0, I1]`
+    reveal_type(t[None:2:None])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I1, I2, I3]`
+    reveal_type(t[1:None:1])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I0, I1, I2, I3]`
+    reveal_type(t[None:None:None])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+
+    start = 1
+    stop = None
+    step = 2
+    # TODO: should be `tuple[I1, I3]`
+    reveal_type(t[start:stop:step])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+
+    # TODO: should be `tuple[I0]`
+    reveal_type(t[False:True])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+    # TODO: should be `tuple[I1, I2]`
+    reveal_type(t[True:3])  # revealed: tuple[I0 | I1 | I2 | I3, ...]
+
+    # TODO: we should emit `zero-stepsize-in-slice` on all of these:
+    t[0:4:0]
+    t[:4:0]
+    t[0::0]
+    t[::0]
+
+    tuple_slice = t[m:n]
+    reveal_type(tuple_slice)  # revealed: tuple[I0 | I1 | I2 | I3, ...]
 ```
 
-## Slices of homogeneous and mixed tuples
+## Indexes into homogeneous and mixed tuples
 
 ```toml
 [environment]

crates/ty_python_semantic/resources/mdtest/type_compendium/tuple.md

@@ -477,4 +477,52 @@ class NotAlwaysTruthyTuple(tuple[int]):
 t: tuple[int] = NotAlwaysTruthyTuple((1,))
 ```
 
+## Unspecialized
+
+An unspecialized tuple is equivalent to `tuple[Any, ...]` and `tuple[Unknown, ...]`.
+
+```py
+from typing_extensions import Any, assert_type
+from ty_extensions import Unknown, is_equivalent_to, static_assert
+
+static_assert(is_equivalent_to(tuple[Any, ...], tuple[Unknown, ...]))
+
+def f(x: tuple, y: tuple[Unknown, ...]):
+    reveal_type(x)  # revealed: tuple[Unknown, ...]
+    assert_type(x, tuple[Any, ...])
+    assert_type(x, tuple[Unknown, ...])
+    reveal_type(y)  # revealed: tuple[Unknown, ...]
+    assert_type(y, tuple[Any, ...])
+    assert_type(y, tuple[Unknown, ...])
+```
+
+## Converting a `tuple` to another `Sequence` type
+
+For covariant types, such as `frozenset`, the ideal behaviour would be to not promote `Literal`
+types to their instance supertypes: doing so causes more false positives than it fixes:
+
+```py
+# TODO: should be `frozenset[Literal[1, 2, 3]]`
+reveal_type(frozenset((1, 2, 3)))  # revealed: frozenset[Unknown]
+# TODO: should be `frozenset[tuple[Literal[1], Literal[2], Literal[3]]]`
+reveal_type(frozenset(((1, 2, 3),)))  # revealed: frozenset[Unknown]
+```
+
+Literals are always promoted for invariant containers such as `list`, however, even though this can
+in some cases cause false positives:
+
+```py
+from typing import Literal
+
+# TODO: should be `list[int]`
+reveal_type(list((1, 2, 3)))  # revealed: list[Unknown]
+# TODO: should be `list[tuple[int, int, int]]`
+reveal_type(list(((1, 2, 3),)))  # revealed: list[Unknown]
+
+x: list[Literal[1, 2, 3]] = list((1, 2, 3))
+
+# TODO: should be `list[Literal[1, 2, 3]]`
+reveal_type(x)  # revealed: list[Unknown]
+```
+
 [not a singleton type]: https://discuss.python.org/t/should-we-specify-in-the-language-reference-that-the-empty-tuple-is-a-singleton/67957

crates/ty_python_semantic/resources/mdtest/type_properties/is_single_valued.md

@@ -16,6 +16,21 @@ static_assert(is_single_valued(Literal[b"abc"]))
 static_assert(is_single_valued(tuple[()]))
 static_assert(is_single_valued(tuple[Literal[True], Literal[1]]))
 
+class EmptyTupleSubclass(tuple[()]): ...
+class HeterogeneousTupleSubclass(tuple[Literal[True], Literal[1]]): ...
+
+# N.B. this follows from the fact that `EmptyTupleSubclass` is a subtype of `tuple[()]`,
+# and any property recognised for `tuple[()]` should therefore also be recognised for
+# `EmptyTupleSubclass` since an `EmptyTupleSubclass` instance can be used anywhere where
+# `tuple[()]` is accepted. This is only sound, however, if we ban `__eq__` and `__ne__`
+# from being overridden on a tuple subclass. This is something we plan to do as part of
+# our implementation of the Liskov Substitution Principle
+# (https://github.com/astral-sh/ty/issues/166)
+#
+# TODO: these should pass
+static_assert(is_single_valued(EmptyTupleSubclass))  # error: [static-assert-error]
+static_assert(is_single_valued(HeterogeneousTupleSubclass))  # error: [static-assert-error]
+
 static_assert(not is_single_valued(str))
 static_assert(not is_single_valued(Never))
 static_assert(not is_single_valued(Any))
@@ -24,6 +39,10 @@ static_assert(not is_single_valued(Literal[1, 2]))
 
 static_assert(not is_single_valued(tuple[None, int]))
 
+class MultiValuedHeterogeneousTupleSubclass(tuple[None, int]): ...
+
+static_assert(not is_single_valued(MultiValuedHeterogeneousTupleSubclass))
+
 static_assert(not is_single_valued(Callable[..., None]))
 static_assert(not is_single_valued(Callable[[int, str], None]))
 

crates/ty_python_semantic/resources/mdtest/unpacking.md

@@ -407,6 +407,161 @@ def _(value: tuple[int, int, *tuple[str, ...], int]):
     reveal_type(c)  # revealed: int
 ```
 
+## Tuple subclasses
+
+A tuple subclass inherits its heterogeneous unpacking behaviour from its tuple superclass.
+
+```toml
+[environment]
+python-version = "3.11"
+```
+
+```py
+class I0: ...
+class I1: ...
+class I2: ...
+class HeterogeneousTupleSubclass(tuple[I0, I1, I2]): ...
+
+def f(x: HeterogeneousTupleSubclass):
+    a, b, c = x
+
+    # TODO: should be `I0`
+    reveal_type(a)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1`
+    reveal_type(b)  # revealed: I0 | I1 | I2
+    # TODO: should be `I2`
+    reveal_type(c)  # revealed: I0 | I1 | I2
+
+    # TODO: should emit a diagnostic ([invalid-assignment] "Too many values to unpack: Expected 2")
+    d, e = x
+
+    reveal_type(d)  # revealed: I0 | I1 | I2
+    reveal_type(e)  # revealed: I0 | I1 | I2
+
+    # TODO: should emit a diagnostic ([invalid-assignment] "Not enough values to unpack: Expected 4")
+    f, g, h, i = x
+
+    reveal_type(f)  # revealed: I0 | I1 | I2
+    reveal_type(g)  # revealed: I0 | I1 | I2
+    reveal_type(h)  # revealed: I0 | I1 | I2
+    reveal_type(i)  # revealed: I0 | I1 | I2
+
+    [j, *k] = x
+
+    # TODO: should be `I0`
+    reveal_type(j)  # revealed: I0 | I1 | I2
+    # TODO: should be `list[I1 | I2]`
+    reveal_type(k)  # revealed: list[I0 | I1 | I2]
+
+    [l, m, *n] = x
+
+    # TODO: should be `I0`
+    reveal_type(l)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1`
+    reveal_type(m)  # revealed: I0 | I1 | I2
+    # TODO: should be `list[I2]`
+    reveal_type(n)  # revealed: list[I0 | I1 | I2]
+
+    [o, p, q, *r] = x
+
+    # TODO: should be `I0`
+    reveal_type(o)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1`
+    reveal_type(p)  # revealed: I0 | I1 | I2
+    # TODO: should be `I2`
+    reveal_type(q)  # revealed: I0 | I1 | I2
+    # TODO: should be `list[Never]`
+    reveal_type(r)  # revealed: list[I0 | I1 | I2]
+
+    # TODO: should emit a diagnostic ([invalid-assignment] "Not enough values to unpack: Expected at least 4")
+    [s, t, u, v, *w] = x
+    reveal_type(s)  # revealed: I0 | I1 | I2
+    reveal_type(t)  # revealed: I0 | I1 | I2
+    reveal_type(u)  # revealed: I0 | I1 | I2
+    reveal_type(v)  # revealed: I0 | I1 | I2
+    reveal_type(w)  # revealed: list[I0 | I1 | I2]
+
+class MixedTupleSubclass(tuple[I0, *tuple[I1, ...], I2]): ...
+
+def f(x: MixedTupleSubclass):
+    # TODO: should emit a diagnostic: ([invalid-assignment] "Too many values to unpack: Expected 1"`)
+    (a,) = x
+    reveal_type(a)  # revealed: I0 | I1 | I2
+
+    c, d = x
+    # TODO: should be `I0`
+    reveal_type(c)  # revealed: I0 | I1 | I2
+    # TODO: should be `I2`
+    reveal_type(d)  # revealed: I0 | I1 | I2
+
+    e, f, g = x
+
+    # TODO: should be `I0`
+    reveal_type(e)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1`
+    reveal_type(f)  # revealed: I0 | I1 | I2
+    # TODO: should be `I2`
+    reveal_type(g)  # revealed: I0 | I1 | I2
+
+    h, i, j, k = x
+
+    # TODO: should be `I0`
+    reveal_type(h)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1`
+    reveal_type(i)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1`
+    reveal_type(j)  # revealed: I0 | I1 | I2
+    # TODO: should be `I2`
+    reveal_type(k)  # revealed: I0 | I1 | I2
+
+    [l, *m] = x
+
+    # TODO: should be `I0`
+    reveal_type(l)  # revealed: I0 | I1 | I2
+    # TODO: should be `list[I1 | I2]`
+    reveal_type(m)  # revealed: list[I0 | I1 | I2]
+
+    [n, o, *p] = x
+
+    # TODO: should be `I0`
+    reveal_type(n)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1 | I2`
+    reveal_type(o)  # revealed: I0 | I1 | I2
+    # TODO: should be `list[I1 | I2]`
+    reveal_type(p)  # revealed: list[I0 | I1 | I2]
+
+    [o, p, q, *r] = x
+
+    # TODO: should be `I0`
+    reveal_type(o)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1 | I2`
+    reveal_type(p)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1 | I2
+    reveal_type(q)  # revealed: I0 | I1 | I2
+    # TODO: should be `list[I1 | I2]
+    reveal_type(r)  # revealed: list[I0 | I1 | I2]
+
+    s, *t, u = x
+
+    # TODO: should be `I0`
+    reveal_type(s)  # revealed: I0 | I1 | I2
+    # TODO: should be `list[I1]`
+    reveal_type(t)  # revealed: list[I0 | I1 | I2]
+    # TODO: should be `I2`
+    reveal_type(u)  # revealed: I0 | I1 | I2
+
+    aa, bb, *cc, dd = x
+
+    # TODO: should be `I0`
+    reveal_type(aa)  # revealed: I0 | I1 | I2
+    # TODO: should be `I1`
+    reveal_type(bb)  # revealed: I0 | I1 | I2
+    # TODO: should be `list[I1]`
+    reveal_type(cc)  # revealed: list[I0 | I1 | I2]
+    # TODO: should be I2
+    reveal_type(dd)  # revealed: I0 | I1 | I2
+```
+
 ## String
 
 ### Simple unpacking