check-recursive-types.test

-- Tests checking that basic functionality works

[case testRecursiveAliasBasic]
from typing import Dict, List, Union, TypeVar, Sequence

JSON = Union[str, List[JSON], Dict[str, JSON]]

x: JSON = ["foo", {"bar": "baz"}]

reveal_type(x)  # N: Revealed type is "Union[builtins.str, builtins.list[...], builtins.dict[builtins.str, ...]]"
if isinstance(x, list):
    x = x[0]

class Bad: ...
x = ["foo", {"bar": [Bad()]}]  # E: List item 0 has incompatible type "Bad"; expected "Union[str, List[JSON], Dict[str, JSON]]"
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasBasicGenericSubtype]
from typing import Union, TypeVar, Sequence, List

T = TypeVar("T")

Nested = Sequence[Union[T, Nested[T]]]

class Bad: ...
x: Nested[int]
y: Nested[Bad]
x = y  # E: Incompatible types in assignment (expression has type "Nested[Bad]", variable has type "Nested[int]")

NestedOther = Sequence[Union[T, Nested[T]]]

xx: Nested[int]
yy: NestedOther[bool]
xx = yy  # OK
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasBasicGenericInference]
from typing import Union, TypeVar, Sequence, List

T = TypeVar("T")

Nested = Sequence[Union[T, Nested[T]]]

def flatten(arg: Nested[T]) -> List[T]:
    res: List[T] = []
    for item in arg:
        if isinstance(item, Sequence):
            res.extend(flatten(item))
        else:
            res.append(item)
    return res

reveal_type(flatten([1, [2, [3]]]))  # N: Revealed type is "builtins.list[builtins.int]"

class Bad: ...
x: Nested[int] = [1, [2, [3]]]
x = [1, [Bad()]]  # E: List item 0 has incompatible type "Bad"; expected "Union[int, Nested[int]]"
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasGenericInferenceNested]
from typing import Union, TypeVar, Sequence, List

T = TypeVar("T")
class A: ...
class B(A): ...

Nested = Sequence[Union[T, Nested[T]]]

def flatten(arg: Nested[T]) -> List[T]: ...
reveal_type(flatten([[B(), B()]]))  # N: Revealed type is "builtins.list[__main__.B]"
reveal_type(flatten([[[[B()]]]]))  # N: Revealed type is "builtins.list[__main__.B]"
reveal_type(flatten([[B(), [[B()]]]]))  # N: Revealed type is "builtins.list[__main__.B]"
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasNewStyleSupported]
from test import A

x: A
if isinstance(x, list):
    reveal_type(x[0])  # N: Revealed type is "Union[builtins.int, builtins.list[Union[builtins.int, builtins.list[...]]]]"
else:
    reveal_type(x)  # N: Revealed type is "builtins.int"

[file test.pyi]
A = int | list[A]
[builtins fixtures/isinstancelist.pyi]

-- Tests duplicating some existing type alias tests with recursive aliases enabled

[case testRecursiveAliasesMutual]
from typing import Type, Callable, Union

A = Union[B, int]
B = Callable[[C], int]
C = Type[A]
x: A
reveal_type(x)  # N: Revealed type is "Union[def (Union[Type[def (...) -> builtins.int], Type[builtins.int]]) -> builtins.int, builtins.int]"

[case testRecursiveAliasesProhibited-skip]
from typing import Type, Callable, Union

A = Union[B, int]
B = Union[A, int]
C = Type[C]

[case testRecursiveAliasImported]
import lib
x: lib.A
reveal_type(x)  # N: Revealed type is "builtins.list[builtins.list[...]]"

[file lib.pyi]
from typing import List
from other import B
A = List[B]

[file other.pyi]
from typing import List
from lib import A
B = List[A]
[builtins fixtures/list.pyi]

[case testRecursiveAliasViaBaseClass]
from typing import List

x: B
B = List[C]
class C(B): pass

reveal_type(x)  # N: Revealed type is "builtins.list[__main__.C]"
reveal_type(x[0][0])  # N: Revealed type is "__main__.C"
[builtins fixtures/list.pyi]

[case testRecursiveAliasViaBaseClass2]
from typing import NewType, List

x: D
reveal_type(x[0][0])  # N: Revealed type is "__main__.C"

D = List[C]
C = NewType('C', B)

class B(D):
    pass
[builtins fixtures/list.pyi]

[case testRecursiveAliasViaBaseClass3]
from typing import List, Generic, TypeVar, NamedTuple
T = TypeVar('T')

class C(A, B):
    pass
class G(Generic[T]): pass
A = G[C]
class B(NamedTuple):
    x: int

y: C
reveal_type(y.x)  # N: Revealed type is "builtins.int"
reveal_type(y[0])  # N: Revealed type is "builtins.int"
x: A
reveal_type(x)  # N: Revealed type is "__main__.G[Tuple[builtins.int, fallback=__main__.C]]"
[builtins fixtures/list.pyi]

[case testRecursiveAliasViaBaseClassImported]
import a
[file a.py]
from typing import List
from b import D

def f(x: B) -> List[B]: ...
B = List[C]
class C(B): pass

[file b.py]
from a import f
class D: ...
reveal_type(f)  # N: Revealed type is "def (x: builtins.list[a.C]) -> builtins.list[builtins.list[a.C]]"
[builtins fixtures/list.pyi]

[case testRecursiveAliasViaNamedTuple]
from typing import List, NamedTuple, Union

Exp = Union['A', 'B']
class A(NamedTuple('A', [('attr', List[Exp])])): pass
class B(NamedTuple('B', [('val', object)])): pass

def my_eval(exp: Exp) -> int:
    reveal_type(exp) # N: Revealed type is "Union[Tuple[builtins.list[...], fallback=__main__.A], Tuple[builtins.object, fallback=__main__.B]]"
    if isinstance(exp, A):
        my_eval(exp[0][0])
        return my_eval(exp.attr[0])
    if isinstance(exp, B):
        return exp.val  # E: Incompatible return value type (got "object", expected "int")
    return 0

my_eval(A([B(1), B(2)]))
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasesSimplifiedUnion]
from typing import Sequence, TypeVar, Union

class A: ...
class B(A): ...

NestedA = Sequence[Union[A, NestedA]]
NestedB = Sequence[Union[B, NestedB]]
a: NestedA
b: NestedB

T = TypeVar("T")
S = TypeVar("S")
def union(a: T, b: S) -> Union[T, S]: ...

x: int
y = union(a, b)
x = y  # E: Incompatible types in assignment (expression has type "Sequence[Union[A, NestedA]]", variable has type "int")
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasesJoins]
from typing import Sequence, TypeVar, Union

class A: ...
class B(A): ...

NestedA = Sequence[Union[A, NestedA]]
NestedB = Sequence[Union[B, NestedB]]
a: NestedA
b: NestedB
la: Sequence[Sequence[A]]
lb: Sequence[Sequence[B]]

T = TypeVar("T")
def join(a: T, b: T) -> T: ...
x: int

y1 = join(a, b)
x = y1  # E: Incompatible types in assignment (expression has type "Sequence[Union[A, NestedA]]", variable has type "int")
y2 = join(a, lb)
x = y2  # E: Incompatible types in assignment (expression has type "Sequence[Union[A, NestedA]]", variable has type "int")
y3 = join(la, b)
x = y3  # E: Incompatible types in assignment (expression has type "Sequence[Union[Sequence[A], B, NestedB]]", variable has type "int")
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasesRestrictions]
from typing import Sequence, Mapping, Union

A = Sequence[Union[int, A]]
B = Mapping[int, Union[int, B]]

x: int
y: Union[A, B]
if isinstance(y, Sequence):
    x = y  # E: Incompatible types in assignment (expression has type "Sequence[Union[int, A]]", variable has type "int")
else:
    x = y  # E: Incompatible types in assignment (expression has type "Mapping[int, Union[int, B]]", variable has type "int")
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasesRestrictions2]
from typing import Sequence, Union

class A: ...
class B(A): ...

NestedA = Sequence[Union[A, NestedA]]
NestedB = Sequence[Union[B, NestedB]]

a: NestedA
b: NestedB
aa: NestedA

x: int
x = a  # E: Incompatible types in assignment (expression has type "NestedA", variable has type "int")
a = b
x = a  # E: Incompatible types in assignment (expression has type "Sequence[Union[B, NestedB]]", variable has type "int")
b = aa  # E: Incompatible types in assignment (expression has type "NestedA", variable has type "NestedB")
if isinstance(b[0], Sequence):
    a = b[0]
    x = a  # E: Incompatible types in assignment (expression has type "Sequence[Union[B, NestedB]]", variable has type "int")
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasWithRecursiveInstance]
from typing import Sequence, Union, TypeVar

class A: ...
T = TypeVar("T")
Nested = Sequence[Union[T, Nested[T]]]
class B(Sequence[B]): ...

a: Nested[A]
aa: Nested[A]
b: B
a = b  # OK
a = [[b]]  # OK
b = aa  # E: Incompatible types in assignment (expression has type "Nested[A]", variable has type "B")

def join(a: T, b: T) -> T: ...
reveal_type(join(a, b))  # N: Revealed type is "typing.Sequence[Union[__main__.A, typing.Sequence[Union[__main__.A, ...]]]]"
reveal_type(join(b, a))  # N: Revealed type is "typing.Sequence[Union[__main__.A, typing.Sequence[Union[__main__.A, ...]]]]"
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasWithRecursiveInstanceInference]
from typing import Sequence, Union, TypeVar, List

T = TypeVar("T")
Nested = Sequence[Union[T, Nested[T]]]
class B(Sequence[B]): ...

nb: Nested[B] = [B(), [B(), [B()]]]
lb: List[B]

def foo(x: Nested[T]) -> T: ...
reveal_type(foo(lb))  # N: Revealed type is "__main__.B"
reveal_type(foo([B(), [B(), [B()]]]))  # N: Revealed type is "__main__.B"

NestedInv = List[Union[T, NestedInv[T]]]
nib: NestedInv[B] = [B(), [B(), [B()]]]
def bar(x: NestedInv[T]) -> T: ...
reveal_type(bar(nib))  # N: Revealed type is "__main__.B"
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasTopUnion]
from typing import Sequence, Union, TypeVar, List

class A: ...
class B(A): ...

T = TypeVar("T")
PlainNested = Union[T, Sequence[PlainNested[T]]]

x: PlainNested[A]
y: PlainNested[B] = [B(), [B(), [B()]]]
x = y  # OK

xx: PlainNested[B]
yy: PlainNested[A]
xx = yy  # E: Incompatible types in assignment (expression has type "PlainNested[A]", variable has type "PlainNested[B]")

def foo(arg: PlainNested[T]) -> T: ...
lb: List[B]
reveal_type(foo([B(), [B(), [B()]]]))  # N: Revealed type is "__main__.B"
reveal_type(foo(lb))  # N: Revealed type is "__main__.B"
reveal_type(foo(xx))  # N: Revealed type is "__main__.B"
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasInferenceExplicitNonRecursive]
from typing import Sequence, Union, TypeVar, List

T = TypeVar("T")
Nested = Sequence[Union[T, Nested[T]]]
PlainNested = Union[T, Sequence[PlainNested[T]]]

def foo(x: Nested[T]) -> T: ...
def bar(x: PlainNested[T]) -> T: ...

class A: ...
a: A
la: List[A]
lla: List[Union[A, List[A]]]
llla: List[Union[A, List[Union[A, List[A]]]]]

reveal_type(foo(la))  # N: Revealed type is "__main__.A"
reveal_type(foo(lla))  # N: Revealed type is "__main__.A"
reveal_type(foo(llla))  # N: Revealed type is "__main__.A"

reveal_type(bar(a))  # N: Revealed type is "__main__.A"
reveal_type(bar(la))  # N: Revealed type is "__main__.A"
reveal_type(bar(lla))  # N: Revealed type is "__main__.A"
reveal_type(bar(llla))  # N: Revealed type is "__main__.A"
[builtins fixtures/isinstancelist.pyi]

[case testRecursiveAliasesWithOptional]
from typing import Optional, Sequence

A = Sequence[Optional[A]]
x: A
y: str = x[0]  # E: Incompatible types in assignment (expression has type "Optional[A]", variable has type "str")

[case testRecursiveAliasesProhibitBadAliases]
from typing import Union, Type, List, TypeVar

NR = List[int]
NR2 = Union[NR, NR]
NR3 = Union[NR, Union[NR2, NR2]]

T = TypeVar("T")
NRG = Union[int, T]
NR4 = NRG[str]
NR5 = Union[NRG[int], NR4]

A = Union[B, int]  # E: Invalid recursive alias: a union item of itself
B = Union[int, A]  # Error reported above
def f() -> A: ...
reveal_type(f())  # N: Revealed type is "Any"

G = Union[T, G[T]]  # E: Invalid recursive alias: a union item of itself
GL = Union[T, GL[List[T]]]  # E: Invalid recursive alias: a union item of itself \
                            # E: Invalid recursive alias: type variable nesting on right hand side
def g() -> G[int]: ...
reveal_type(g())  # N: Revealed type is "Any"

def local() -> None:
    L = List[Union[int, L]]  # E: Cannot resolve name "L" (possible cyclic definition) \
                             # N: Recursive types are not allowed at function scope
    x: L
    reveal_type(x)  # N: Revealed type is "builtins.list[Union[builtins.int, Any]]"

S = Type[S]  # E: Type[...] cannot contain another Type[...]
U = Type[Union[int, U]]  # E: Type[...] cannot contain another Type[...]
x: U
reveal_type(x)  # N: Revealed type is "Type[Any]"

D = List[F[List[T]]]  # E: Invalid recursive alias: type variable nesting on right hand side
F = D[T]  # Error reported above
E = List[E[E[T]]]  # E: Invalid recursive alias: type variable nesting on right hand side
d: D
reveal_type(d)  # N: Revealed type is "Any"
[builtins fixtures/isinstancelist.pyi]

[case testBasicRecursiveNamedTuple]
# flags: --strict-optional
from typing import NamedTuple, Optional

NT = NamedTuple("NT", [("x", Optional[NT]), ("y", int)])
nt: NT
reveal_type(nt)  # N: Revealed type is "Tuple[Union[..., None], builtins.int, fallback=__main__.NT]"
reveal_type(nt.x)  # N: Revealed type is "Union[Tuple[Union[..., None], builtins.int, fallback=__main__.NT], None]"
reveal_type(nt[0])  # N: Revealed type is "Union[Tuple[Union[..., None], builtins.int, fallback=__main__.NT], None]"
y: str
if nt.x is not None:
    y = nt.x[0]  # E: Incompatible types in assignment (expression has type "Optional[NT]", variable has type "str")
[builtins fixtures/tuple.pyi]

[case testBasicRecursiveNamedTupleSpecial]
from typing import NamedTuple, TypeVar, Tuple

NT = NamedTuple("NT", [("x", NT), ("y", int)])
nt: NT
reveal_type(nt)  # N: Revealed type is "Tuple[..., builtins.int, fallback=__main__.NT]"
reveal_type(nt.x)  # N: Revealed type is "Tuple[Tuple[..., builtins.int, fallback=__main__.NT], builtins.int, fallback=__main__.NT]"
reveal_type(nt[0])  # N: Revealed type is "Tuple[Tuple[..., builtins.int, fallback=__main__.NT], builtins.int, fallback=__main__.NT]"
y: str
if nt.x is not None:
    y = nt.x[0]  # E: Incompatible types in assignment (expression has type "NT", variable has type "str")

T = TypeVar("T")
def f(a: T, b: T) -> T: ...
tnt: Tuple[NT]

# TODO: these should be tuple[object] instead.
reveal_type(f(nt, tnt))  # N: Revealed type is "builtins.tuple[Any, ...]"
reveal_type(f(tnt, nt))  # N: Revealed type is "builtins.tuple[Any, ...]"
[builtins fixtures/tuple.pyi]

[case testBasicRecursiveNamedTupleClass]
# flags: --strict-optional
from typing import NamedTuple, Optional

class NT(NamedTuple):
    x: Optional[NT]
    y: int

nt: NT
reveal_type(nt)  # N: Revealed type is "Tuple[Union[..., None], builtins.int, fallback=__main__.NT]"
reveal_type(nt.x)  # N: Revealed type is "Union[Tuple[Union[..., None], builtins.int, fallback=__main__.NT], None]"
reveal_type(nt[0])  # N: Revealed type is "Union[Tuple[Union[..., None], builtins.int, fallback=__main__.NT], None]"
y: str
if nt.x is not None:
    y = nt.x[0]  # E: Incompatible types in assignment (expression has type "Optional[NT]", variable has type "str")
[builtins fixtures/tuple.pyi]

[case testRecursiveRegularTupleClass]
from typing import Tuple

x: B
class B(Tuple[B, int]):
    x: int

b, _ = x
reveal_type(b.x)  # N: Revealed type is "builtins.int"
[builtins fixtures/tuple.pyi]

[case testRecursiveTupleClassesNewType]
from typing import Tuple, NamedTuple, NewType

x: C
class B(Tuple[B, int]):
    x: int
C = NewType("C", B)
b, _ = x
reveal_type(b)  # N: Revealed type is "Tuple[..., builtins.int, fallback=__main__.B]"
reveal_type(b.x)  # N: Revealed type is "builtins.int"

y: CNT
class BNT(NamedTuple):
    x: CNT
    y: int
CNT = NewType("CNT", BNT)
bnt, _ = y
reveal_type(bnt.y)  # N: Revealed type is "builtins.int"
[builtins fixtures/tuple.pyi]

-- Tests duplicating some existing named tuple tests with recursive aliases enabled

[case testMutuallyRecursiveNamedTuples]
from typing import Tuple, NamedTuple, TypeVar, Union

A = NamedTuple('A', [('x', str), ('y', Tuple[B, ...])])
class B(NamedTuple):
    x: A
    y: int

n: A
reveal_type(n) # N: Revealed type is "Tuple[builtins.str, builtins.tuple[Tuple[..., builtins.int, fallback=__main__.B], ...], fallback=__main__.A]"

T = TypeVar("T")
S = TypeVar("S")
def foo(arg: Tuple[T, S]) -> Union[T, S]: ...
x = foo(n)
y: str = x  # E: Incompatible types in assignment (expression has type "Union[str, Tuple[B, ...]]", variable has type "str")
[builtins fixtures/tuple.pyi]

[case testMutuallyRecursiveNamedTuplesJoin]
from typing import NamedTuple, Tuple

class B(NamedTuple):
    x: Tuple[A, int]
    y: int

A = NamedTuple('A', [('x', str), ('y', B)])
n: B
m: A
s: str = n.x  # E: Incompatible types in assignment (expression has type "Tuple[A, int]", variable has type "str")
reveal_type(m[0]) # N: Revealed type is "builtins.str"
lst = [m, n]

# Unfortunately, join of two recursive types is not very precise.
reveal_type(lst[0]) # N: Revealed type is "builtins.object"

# These just should not crash
lst1 = [m]
lst2 = [m, m]
lst3 = [m, m, m]
[builtins fixtures/tuple.pyi]

[case testMutuallyRecursiveNamedTuplesClasses]
from typing import NamedTuple, Tuple

class B(NamedTuple):
    x: A
    y: int
class A(NamedTuple):
    x: str
    y: B

n: A
s: str = n.y[0]  # E: Incompatible types in assignment (expression has type "A", variable has type "str")

m: B
n = m.x
n = n.y.x

t: Tuple[str, B]
t = n
t = m  # E: Incompatible types in assignment (expression has type "B", variable has type "Tuple[str, B]")
[builtins fixtures/tuple.pyi]

[case testMutuallyRecursiveNamedTuplesCalls]
from typing import NamedTuple

B = NamedTuple('B', [('x', A), ('y', int)])
A = NamedTuple('A', [('x', str), ('y', 'B')])
n: A
def f(m: B) -> None: pass
reveal_type(n) # N: Revealed type is "Tuple[builtins.str, Tuple[..., builtins.int, fallback=__main__.B], fallback=__main__.A]"
reveal_type(f) # N: Revealed type is "def (m: Tuple[Tuple[builtins.str, ..., fallback=__main__.A], builtins.int, fallback=__main__.B])"
f(n)  # E: Argument 1 to "f" has incompatible type "A"; expected "B"
[builtins fixtures/tuple.pyi]

[case testNoRecursiveTuplesAtFunctionScope]
from typing import NamedTuple, Tuple
def foo() -> None:
    class B(NamedTuple):
        x: B  # E: Cannot resolve name "B" (possible cyclic definition) \
              # N: Recursive types are not allowed at function scope
        y: int
    b: B
    reveal_type(b)  # N: Revealed type is "Tuple[Any, builtins.int, fallback=__main__.B@3]"
[builtins fixtures/tuple.pyi]

[case testBasicRecursiveGenericNamedTuple]
from typing import Generic, NamedTuple, TypeVar, Union

T = TypeVar("T", covariant=True)
class NT(NamedTuple, Generic[T]):
    key: int
    value: Union[T, NT[T]]

class A: ...
class B(A): ...

nti: NT[int] = NT(key=0, value=NT(key=1, value=A()))  # E: Argument "value" to "NT" has incompatible type "A"; expected "Union[int, NT[int]]"
reveal_type(nti)  # N: Revealed type is "Tuple[builtins.int, Union[builtins.int, ...], fallback=__main__.NT[builtins.int]]"

nta: NT[A]
ntb: NT[B]
nta = ntb  # OK, covariance
ntb = nti  # E: Incompatible types in assignment (expression has type "NT[int]", variable has type "NT[B]")

def last(arg: NT[T]) -> T: ...
reveal_type(last(ntb))  # N: Revealed type is "__main__.B"
[builtins fixtures/tuple.pyi]

[case testBasicRecursiveTypedDictClass]
from typing import TypedDict

class TD(TypedDict):
    x: int
    y: TD

td: TD
reveal_type(td)  # N: Revealed type is "TypedDict('__main__.TD', {'x': builtins.int, 'y': ...})"
s: str = td["y"]  # E: Incompatible types in assignment (expression has type "TD", variable has type "str")
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testBasicRecursiveTypedDictCall]
from typing import TypedDict

TD = TypedDict("TD", {"x": int, "y": TD})
td: TD
reveal_type(td)  # N: Revealed type is "TypedDict('__main__.TD', {'x': builtins.int, 'y': ...})"

TD2 = TypedDict("TD2", {"x": int, "y": TD2})
td2: TD2
TD3 = TypedDict("TD3", {"x": str, "y": TD3})
td3: TD3

td = td2
td = td3  # E: Incompatible types in assignment (expression has type "TD3", variable has type "TD")
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testBasicRecursiveTypedDictExtending]
from typing import TypedDict

class TDA(TypedDict):
    xa: int
    ya: TD

class TDB(TypedDict):
    xb: int
    yb: TD

class TD(TDA, TDB):
    a: TDA
    b: TDB

td: TD
reveal_type(td)  # N: Revealed type is "TypedDict('__main__.TD', {'xb': builtins.int, 'yb': ..., 'xa': builtins.int, 'ya': ..., 'a': TypedDict('__main__.TDA', {'xa': builtins.int, 'ya': ...}), 'b': TypedDict('__main__.TDB', {'xb': builtins.int, 'yb': ...})})"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testRecursiveTypedDictCreation]
from typing import TypedDict, Optional

class TD(TypedDict):
    x: int
    y: Optional[TD]

td: TD = {"x": 0, "y": None}
td2: TD = {"x": 0, "y": {"x": 1, "y": {"x": 2, "y": None}}}

itd = TD(x=0, y=None)
itd2 = TD(x=0, y=TD(x=0, y=TD(x=0, y=None)))
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testRecursiveTypedDictMethods]
# flags: --strict-optional
from typing import TypedDict

class TD(TypedDict, total=False):
    x: int
    y: TD

td: TD
td["y"] = {"x": 0, "y": {}}
td["y"] = {"x": 0, "y": {"x": 0, "y": 42}}  # E: Incompatible types (expression has type "int", TypedDict item "y" has type "TD")

reveal_type(td.get("y"))  # N: Revealed type is "Union[TypedDict('__main__.TD', {'x'?: builtins.int, 'y'?: TypedDict('__main__.TD', {'x'?: builtins.int, 'y'?: ...})}), None]"
s: str = td.get("y")  # E: Incompatible types in assignment (expression has type "Optional[TD]", variable has type "str")

td.update({"x": 0, "y": {"x": 1, "y": {}}})
td.update({"x": 0, "y": {"x": 1, "y": {"x": 2, "y": 42}}})  # E: Incompatible types (expression has type "int", TypedDict item "y" has type "TD")
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testRecursiveTypedDictSubtyping]
from typing import TypedDict

class TDA1(TypedDict):
    x: int
    y: TDA1
class TDA2(TypedDict):
    x: int
    y: TDA2
class TDB(TypedDict):
    x: str
    y: TDB

tda1: TDA1
tda2: TDA2
tdb: TDB
def fa1(arg: TDA1) -> None: ...
def fa2(arg: TDA2) -> None: ...
def fb(arg: TDB) -> None: ...

fa1(tda2)
fa2(tda1)
fb(tda1)  # E: Argument 1 to "fb" has incompatible type "TDA1"; expected "TDB"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testRecursiveTypedDictJoin]
from typing import TypedDict, TypeVar

class TDA1(TypedDict):
    x: int
    y: TDA1
class TDA2(TypedDict):
    x: int
    y: TDA2
class TDB(TypedDict):
    x: str
    y: TDB

tda1: TDA1
tda2: TDA2
tdb: TDB

T = TypeVar("T")
def f(x: T, y: T) -> T: ...
# Join for recursive types is very basic, but just add tests that we don't crash.
reveal_type(f(tda1, tda2))  # N: Revealed type is "TypedDict({'x': builtins.int, 'y': TypedDict('__main__.TDA1', {'x': builtins.int, 'y': ...})})"
reveal_type(f(tda1, tdb))  # N: Revealed type is "TypedDict({})"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testBasicRecursiveGenericTypedDict]
from typing import TypedDict, TypeVar, Generic, Optional, List

T = TypeVar("T")
class Tree(TypedDict, Generic[T], total=False):
    value: T
    left: Tree[T]
    right: Tree[T]

def collect(arg: Tree[T]) -> List[T]: ...

reveal_type(collect({"left": {"right": {"value": 0}}}))  # N: Revealed type is "builtins.list[builtins.int]"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testRecursiveGenericTypedDictExtending]
from typing import TypedDict, Generic, TypeVar, List

T = TypeVar("T")

class TD(TypedDict, Generic[T]):
    val: T
    other: STD[T]
class STD(TD[T]):
    sval: T
    one: TD[T]

std: STD[str]
reveal_type(std)  # N: Revealed type is "TypedDict('__main__.STD', {'val': builtins.str, 'other': ..., 'sval': builtins.str, 'one': TypedDict('__main__.TD', {'val': builtins.str, 'other': ...})})"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testRecursiveClassLevelAlias]
# flags: --strict-optional
from typing import Union, Sequence

class A:
    Children = Union[Sequence['Children'], 'A', None]
x: A.Children
reveal_type(x)  # N: Revealed type is "Union[typing.Sequence[...], __main__.A, None]"

class B:
    Foo = Sequence[Bar]
    Bar = Sequence[Foo]
y: B.Foo
reveal_type(y)  # N: Revealed type is "typing.Sequence[typing.Sequence[...]]"
[builtins fixtures/tuple.pyi]

[case testNoCrashOnRecursiveTupleFallback]
from typing import Union, Tuple

Tree1 = Union[str, Tuple[Tree1]]
Tree2 = Union[str, Tuple[Tree2, Tree2]]
Tree3 = Union[str, Tuple[Tree3, Tree3, Tree3]]

def test1() -> Tree1:
    return 42  # E: Incompatible return value type (got "int", expected "Union[str, Tuple[Tree1]]")
def test2() -> Tree2:
    return 42  # E: Incompatible return value type (got "int", expected "Union[str, Tuple[Tree2, Tree2]]")
def test3() -> Tree3:
    return 42  # E: Incompatible return value type (got "int", expected "Union[str, Tuple[Tree3, Tree3, Tree3]]")
[builtins fixtures/tuple.pyi]

[case testRecursiveDoubleUnionNoCrash]
from typing import Tuple, Union, Callable, Sequence

K = Union[int, Tuple[Union[int, K]]]
L = Union[int, Callable[[], Union[int, L]]]
M = Union[int, Sequence[Union[int, M]]]

x: K
x = x
y: L
y = y
z: M
z = z

x = y  # E: Incompatible types in assignment (expression has type "L", variable has type "K")
z = x  # OK
[builtins fixtures/tuple.pyi]