check-narrowing.test

[case testNarrowingParentWithStrsBasic]
# flags: --strict-equality --warn-unreachable
from dataclasses import dataclass
from typing import Literal, NamedTuple, Tuple, TypedDict, Union

class Object1:
    key: Literal["A"]
    foo: int
class Object2:
    key: Literal["B"]
    bar: str

@dataclass
class Dataclass1:
    key: Literal["A"]
    foo: int
@dataclass
class Dataclass2:
    key: Literal["B"]
    foo: str

class NamedTuple1(NamedTuple):
    key: Literal["A"]
    foo: int
class NamedTuple2(NamedTuple):
    key: Literal["B"]
    foo: str

Tuple1 = Tuple[Literal["A"], int]
Tuple2 = Tuple[Literal["B"], str]

class TypedDict1(TypedDict):
    key: Literal["A"]
    foo: int
class TypedDict2(TypedDict):
    key: Literal["B"]
    foo: str

x1: Union[Object1, Object2]
if x1.key == "A":
    reveal_type(x1)         # N: Revealed type is "__main__.Object1"
    reveal_type(x1.key)     # N: Revealed type is "Literal['A']"
else:
    reveal_type(x1)         # N: Revealed type is "__main__.Object2"
    reveal_type(x1.key)     # N: Revealed type is "Literal['B']"

x2: Union[Dataclass1, Dataclass2]
if x2.key == "A":
    reveal_type(x2)         # N: Revealed type is "__main__.Dataclass1"
    reveal_type(x2.key)     # N: Revealed type is "Literal['A']"
else:
    reveal_type(x2)         # N: Revealed type is "__main__.Dataclass2"
    reveal_type(x2.key)     # N: Revealed type is "Literal['B']"

x3: Union[NamedTuple1, NamedTuple2]
if x3.key == "A":
    reveal_type(x3)         # N: Revealed type is "tuple[Literal['A'], builtins.int, fallback=__main__.NamedTuple1]"
    reveal_type(x3.key)     # N: Revealed type is "Literal['A']"
else:
    reveal_type(x3)         # N: Revealed type is "tuple[Literal['B'], builtins.str, fallback=__main__.NamedTuple2]"
    reveal_type(x3.key)     # N: Revealed type is "Literal['B']"
if x3[0] == "A":
    reveal_type(x3)         # N: Revealed type is "tuple[Literal['A'], builtins.int, fallback=__main__.NamedTuple1]"
    reveal_type(x3[0])      # N: Revealed type is "Literal['A']"
else:
    reveal_type(x3)         # N: Revealed type is "tuple[Literal['B'], builtins.str, fallback=__main__.NamedTuple2]"
    reveal_type(x3[0])      # N: Revealed type is "Literal['B']"

x4: Union[Tuple1, Tuple2]
if x4[0] == "A":
    reveal_type(x4)         # N: Revealed type is "tuple[Literal['A'], builtins.int]"
    reveal_type(x4[0])      # N: Revealed type is "Literal['A']"
else:
    reveal_type(x4)         # N: Revealed type is "tuple[Literal['B'], builtins.str]"
    reveal_type(x4[0])      # N: Revealed type is "Literal['B']"

x5: Union[TypedDict1, TypedDict2]
if x5["key"] == "A":
    reveal_type(x5)         # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key': Literal['A'], 'foo': builtins.int})"
else:
    reveal_type(x5)         # N: Revealed type is "TypedDict('__main__.TypedDict2', {'key': Literal['B'], 'foo': builtins.str})"
[builtins fixtures/primitives.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingParentWithEnumsBasic]
# flags: --strict-equality --warn-unreachable
from enum import Enum
from dataclasses import dataclass
from typing import Literal, NamedTuple, Tuple, TypedDict, Union

class Key(Enum):
    A = 1
    B = 2
    C = 3

class Object1:
    key: Literal[Key.A]
    foo: int
class Object2:
    key: Literal[Key.B]
    bar: str

@dataclass
class Dataclass1:
    key: Literal[Key.A]
    foo: int
@dataclass
class Dataclass2:
    key: Literal[Key.B]
    foo: str

class NamedTuple1(NamedTuple):
    key: Literal[Key.A]
    foo: int
class NamedTuple2(NamedTuple):
    key: Literal[Key.B]
    foo: str

Tuple1 = Tuple[Literal[Key.A], int]
Tuple2 = Tuple[Literal[Key.B], str]

class TypedDict1(TypedDict):
    key: Literal[Key.A]
    foo: int
class TypedDict2(TypedDict):
    key: Literal[Key.B]
    foo: str

x1: Union[Object1, Object2]
if x1.key is Key.A:
    reveal_type(x1)         # N: Revealed type is "__main__.Object1"
    reveal_type(x1.key)     # N: Revealed type is "Literal[__main__.Key.A]"
else:
    reveal_type(x1)         # N: Revealed type is "__main__.Object2"
    reveal_type(x1.key)     # N: Revealed type is "Literal[__main__.Key.B]"

x2: Union[Dataclass1, Dataclass2]
if x2.key is Key.A:
    reveal_type(x2)         # N: Revealed type is "__main__.Dataclass1"
    reveal_type(x2.key)     # N: Revealed type is "Literal[__main__.Key.A]"
else:
    reveal_type(x2)         # N: Revealed type is "__main__.Dataclass2"
    reveal_type(x2.key)     # N: Revealed type is "Literal[__main__.Key.B]"

x3: Union[NamedTuple1, NamedTuple2]
if x3.key is Key.A:
    reveal_type(x3)         # N: Revealed type is "tuple[Literal[__main__.Key.A], builtins.int, fallback=__main__.NamedTuple1]"
    reveal_type(x3.key)     # N: Revealed type is "Literal[__main__.Key.A]"
else:
    reveal_type(x3)         # N: Revealed type is "tuple[Literal[__main__.Key.B], builtins.str, fallback=__main__.NamedTuple2]"
    reveal_type(x3.key)     # N: Revealed type is "Literal[__main__.Key.B]"
if x3[0] is Key.A:
    reveal_type(x3)         # N: Revealed type is "tuple[Literal[__main__.Key.A], builtins.int, fallback=__main__.NamedTuple1]"
    reveal_type(x3[0])      # N: Revealed type is "Literal[__main__.Key.A]"
else:
    reveal_type(x3)         # N: Revealed type is "tuple[Literal[__main__.Key.B], builtins.str, fallback=__main__.NamedTuple2]"
    reveal_type(x3[0])      # N: Revealed type is "Literal[__main__.Key.B]"

x4: Union[Tuple1, Tuple2]
if x4[0] is Key.A:
    reveal_type(x4)         # N: Revealed type is "tuple[Literal[__main__.Key.A], builtins.int]"
    reveal_type(x4[0])      # N: Revealed type is "Literal[__main__.Key.A]"
else:
    reveal_type(x4)         # N: Revealed type is "tuple[Literal[__main__.Key.B], builtins.str]"
    reveal_type(x4[0])      # N: Revealed type is "Literal[__main__.Key.B]"

x5: Union[TypedDict1, TypedDict2]
if x5["key"] is Key.A:
    reveal_type(x5)         # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key': Literal[__main__.Key.A], 'foo': builtins.int})"
else:
    reveal_type(x5)         # N: Revealed type is "TypedDict('__main__.TypedDict2', {'key': Literal[__main__.Key.B], 'foo': builtins.str})"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingParentWithIsInstanceBasic]
# flags: --strict-equality --warn-unreachable
from dataclasses import dataclass
from typing import NamedTuple, Tuple, TypedDict, Union

class Object1:
    key: int
class Object2:
    key: str

@dataclass
class Dataclass1:
    key: int
@dataclass
class Dataclass2:
    key: str

class NamedTuple1(NamedTuple):
    key: int
class NamedTuple2(NamedTuple):
    key: str

Tuple1 = Tuple[int]
Tuple2 = Tuple[str]

class TypedDict1(TypedDict):
    key: int
class TypedDict2(TypedDict):
    key: str

x1: Union[Object1, Object2]
if isinstance(x1.key, int):
    reveal_type(x1)         # N: Revealed type is "__main__.Object1"
else:
    reveal_type(x1)         # N: Revealed type is "__main__.Object2"

x2: Union[Dataclass1, Dataclass2]
if isinstance(x2.key, int):
    reveal_type(x2)         # N: Revealed type is "__main__.Dataclass1"
else:
    reveal_type(x2)         # N: Revealed type is "__main__.Dataclass2"

x3: Union[NamedTuple1, NamedTuple2]
if isinstance(x3.key, int):
    reveal_type(x3)         # N: Revealed type is "tuple[builtins.int, fallback=__main__.NamedTuple1]"
else:
    reveal_type(x3)         # N: Revealed type is "tuple[builtins.str, fallback=__main__.NamedTuple2]"
if isinstance(x3[0], int):
    reveal_type(x3)         # N: Revealed type is "tuple[builtins.int, fallback=__main__.NamedTuple1]"
else:
    reveal_type(x3)         # N: Revealed type is "tuple[builtins.str, fallback=__main__.NamedTuple2]"

x4: Union[Tuple1, Tuple2]
if isinstance(x4[0], int):
    reveal_type(x4)         # N: Revealed type is "tuple[builtins.int]"
else:
    reveal_type(x4)         # N: Revealed type is "tuple[builtins.str]"

x5: Union[TypedDict1, TypedDict2]
if isinstance(x5["key"], int):
    reveal_type(x5)         # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key': builtins.int})"
else:
    reveal_type(x5)         # N: Revealed type is "TypedDict('__main__.TypedDict2', {'key': builtins.str})"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingParentMultipleKeys]
# flags: --strict-equality --warn-unreachable
from enum import Enum
from typing import Literal, Union

class Key(Enum):
    A = 1
    B = 2
    C = 3
    D = 4

class Object1:
    key: Literal[Key.A, Key.C]
class Object2:
    key: Literal[Key.B, Key.C]

x: Union[Object1, Object2]
if x.key is Key.A:
    reveal_type(x)  # N: Revealed type is "__main__.Object1"
else:
    reveal_type(x)  # N: Revealed type is "__main__.Object1 | __main__.Object2"

if x.key is Key.C:
    reveal_type(x)  # N: Revealed type is "__main__.Object1 | __main__.Object2"
else:
    reveal_type(x)  # N: Revealed type is "__main__.Object1 | __main__.Object2"

if x.key is Key.D:  # E: Non-overlapping identity check (left operand type: "Literal[Key.A, Key.C, Key.B]", right operand type: "Literal[Key.D]")
    reveal_type(x)  # E: Statement is unreachable
else:
    reveal_type(x)  # N: Revealed type is "__main__.Object1 | __main__.Object2"
[builtins fixtures/tuple.pyi]

[case testNarrowingTypedDictParentMultipleKeys]
# flags: --strict-equality --warn-unreachable
from typing import Literal, TypedDict, Union

class TypedDict1(TypedDict):
    key: Literal['A', 'C']
class TypedDict2(TypedDict):
    key: Literal['B', 'C']

x: Union[TypedDict1, TypedDict2]
if x['key'] == 'A':
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key': Literal['A'] | Literal['C']})"
else:
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key': Literal['A'] | Literal['C']}) | TypedDict('__main__.TypedDict2', {'key': Literal['B'] | Literal['C']})"

if x['key'] == 'C':
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key': Literal['A'] | Literal['C']}) | TypedDict('__main__.TypedDict2', {'key': Literal['B'] | Literal['C']})"
else:
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key': Literal['A'] | Literal['C']}) | TypedDict('__main__.TypedDict2', {'key': Literal['B'] | Literal['C']})"

if x['key'] == 'D':  # E: Non-overlapping equality check (left operand type: "Literal['A', 'C', 'B']", right operand type: "Literal['D']")
    reveal_type(x)  # E: Statement is unreachable
else:
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key': Literal['A'] | Literal['C']}) | TypedDict('__main__.TypedDict2', {'key': Literal['B'] | Literal['C']})"
[builtins fixtures/primitives.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingPartialTypedDictParentMultipleKeys]
# flags: --strict-equality --warn-unreachable
from typing import Literal, TypedDict, Union

class TypedDict1(TypedDict, total=False):
    key: Literal['A', 'C']
class TypedDict2(TypedDict, total=False):
    key: Literal['B', 'C']

x: Union[TypedDict1, TypedDict2]
if x['key'] == 'A':
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key'?: Literal['A'] | Literal['C']})"
else:
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key'?: Literal['A'] | Literal['C']}) | TypedDict('__main__.TypedDict2', {'key'?: Literal['B'] | Literal['C']})"

if x['key'] == 'C':
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key'?: Literal['A'] | Literal['C']}) | TypedDict('__main__.TypedDict2', {'key'?: Literal['B'] | Literal['C']})"
else:
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key'?: Literal['A'] | Literal['C']}) | TypedDict('__main__.TypedDict2', {'key'?: Literal['B'] | Literal['C']})"

if x['key'] == 'D':  # E: Non-overlapping equality check (left operand type: "Literal['A', 'C', 'B']", right operand type: "Literal['D']")
    reveal_type(x)  # E: Statement is unreachable
else:
    reveal_type(x)  # N: Revealed type is "TypedDict('__main__.TypedDict1', {'key'?: Literal['A'] | Literal['C']}) | TypedDict('__main__.TypedDict2', {'key'?: Literal['B'] | Literal['C']})"
[builtins fixtures/primitives.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingNestedTypedDicts]
# flags: --strict-equality --warn-unreachable
from typing import Literal, TypedDict, Union

class A(TypedDict):
    key: Literal['A']
class B(TypedDict):
    key: Literal['B']
class C(TypedDict):
    key: Literal['C']

class X(TypedDict):
    inner: Union[A, B]
class Y(TypedDict):
    inner: Union[B, C]

unknown: Union[X, Y]
if unknown['inner']['key'] == 'A':
    reveal_type(unknown)            # N: Revealed type is "TypedDict('__main__.X', {'inner': TypedDict('__main__.A', {'key': Literal['A']}) | TypedDict('__main__.B', {'key': Literal['B']})})"
    reveal_type(unknown['inner'])   # N: Revealed type is "TypedDict('__main__.A', {'key': Literal['A']})"
if unknown['inner']['key'] == 'B':
    reveal_type(unknown)            # N: Revealed type is "TypedDict('__main__.X', {'inner': TypedDict('__main__.A', {'key': Literal['A']}) | TypedDict('__main__.B', {'key': Literal['B']})}) | TypedDict('__main__.Y', {'inner': TypedDict('__main__.B', {'key': Literal['B']}) | TypedDict('__main__.C', {'key': Literal['C']})})"
    reveal_type(unknown['inner'])   # N: Revealed type is "TypedDict('__main__.B', {'key': Literal['B']})"
if unknown['inner']['key'] == 'C':
    reveal_type(unknown)            # N: Revealed type is "TypedDict('__main__.Y', {'inner': TypedDict('__main__.B', {'key': Literal['B']}) | TypedDict('__main__.C', {'key': Literal['C']})})"
    reveal_type(unknown['inner'])   # N: Revealed type is "TypedDict('__main__.C', {'key': Literal['C']})"
[builtins fixtures/primitives.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingParentWithMultipleParents]
# flags: --strict-equality --warn-unreachable
from enum import Enum
from typing import Literal, Union

class Key(Enum):
    A = 1
    B = 2
    C = 3

class Object1:
    key: Literal[Key.A]
class Object2:
    key: Literal[Key.B]
class Object3:
    key: Literal[Key.C]
class Object4:
    key: str

x: Union[Object1, Object2, Object3, Object4]
if x.key is Key.A:
    reveal_type(x)  # N: Revealed type is "__main__.Object1"
else:
    reveal_type(x)  # N: Revealed type is "__main__.Object2 | __main__.Object3 | __main__.Object4"

if isinstance(x.key, str):
    reveal_type(x)  # N: Revealed type is "__main__.Object4"
else:
    reveal_type(x)  # N: Revealed type is "__main__.Object1 | __main__.Object2 | __main__.Object3"
[builtins fixtures/isinstance.pyi]

[case testNarrowingParentsWithGenerics]
# flags: --strict-equality --warn-unreachable
from typing import Union, TypeVar, Generic

T = TypeVar('T')
class Wrapper(Generic[T]):
    key: T

x: Union[Wrapper[int], Wrapper[str]]
if isinstance(x.key, int):
    reveal_type(x)  # N: Revealed type is "__main__.Wrapper[builtins.int]"
else:
    reveal_type(x)  # N: Revealed type is "__main__.Wrapper[builtins.str]"
[builtins fixtures/isinstance.pyi]

[case testNarrowingParentWithParentMixtures]
# flags: --strict-equality --warn-unreachable
from enum import Enum
from typing import Literal, Union, NamedTuple, TypedDict

class Key(Enum):
    A = 1
    B = 2
    C = 3

class KeyedObject:
    key: Literal[Key.A]
class KeyedTypedDict(TypedDict):
    key: Literal[Key.B]
class KeyedNamedTuple(NamedTuple):
    key: Literal[Key.C]

ok_mixture: Union[KeyedObject, KeyedNamedTuple]
if ok_mixture.key is Key.A:
    reveal_type(ok_mixture)             # N: Revealed type is "__main__.KeyedObject"
else:
    reveal_type(ok_mixture)             # N: Revealed type is "tuple[Literal[__main__.Key.C], fallback=__main__.KeyedNamedTuple]"

impossible_mixture: Union[KeyedObject, KeyedTypedDict]
if impossible_mixture.key is Key.A:     # E: Item "KeyedTypedDict" of "KeyedObject | KeyedTypedDict" has no attribute "key"
    reveal_type(impossible_mixture)     # N: Revealed type is "__main__.KeyedObject | TypedDict('__main__.KeyedTypedDict', {'key': Literal[__main__.Key.B]})"
else:
    reveal_type(impossible_mixture)     # N: Revealed type is "__main__.KeyedObject | TypedDict('__main__.KeyedTypedDict', {'key': Literal[__main__.Key.B]})"

if impossible_mixture["key"] is Key.A:  # E: Value of type "KeyedObject | KeyedTypedDict" is not indexable
    reveal_type(impossible_mixture)     # N: Revealed type is "__main__.KeyedObject | TypedDict('__main__.KeyedTypedDict', {'key': Literal[__main__.Key.B]})"
else:
    reveal_type(impossible_mixture)     # N: Revealed type is "__main__.KeyedObject | TypedDict('__main__.KeyedTypedDict', {'key': Literal[__main__.Key.B]})"

weird_mixture: Union[KeyedTypedDict, KeyedNamedTuple]
if weird_mixture["key"] is Key.B:       # E: No overload variant of "__getitem__" of "tuple" matches argument type "str" \
                                        # N: Possible overload variants: \
                                        # N:     def __getitem__(self, int, /) -> Literal[Key.C] \
                                        # N:     def __getitem__(self, slice, /) -> tuple[Literal[Key.C], ...]
    reveal_type(weird_mixture)          # N: Revealed type is "TypedDict('__main__.KeyedTypedDict', {'key': Literal[__main__.Key.B]}) | tuple[Literal[__main__.Key.C], fallback=__main__.KeyedNamedTuple]"
else:
    reveal_type(weird_mixture)          # N: Revealed type is "TypedDict('__main__.KeyedTypedDict', {'key': Literal[__main__.Key.B]}) | tuple[Literal[__main__.Key.C], fallback=__main__.KeyedNamedTuple]"

if weird_mixture[0] is Key.B:           # E: TypedDict key must be a string literal; expected one of ("key")
    reveal_type(weird_mixture)          # N: Revealed type is "TypedDict('__main__.KeyedTypedDict', {'key': Literal[__main__.Key.B]}) | tuple[Literal[__main__.Key.C], fallback=__main__.KeyedNamedTuple]"
else:
    reveal_type(weird_mixture)          # N: Revealed type is "TypedDict('__main__.KeyedTypedDict', {'key': Literal[__main__.Key.B]}) | tuple[Literal[__main__.Key.C], fallback=__main__.KeyedNamedTuple]"
[builtins fixtures/tuple.pyi]
[typing fixtures/typing-full.pyi]

[case testNarrowingParentWithProperties]
# flags: --strict-equality --warn-unreachable
from enum import Enum
from typing import Literal, Union

class Key(Enum):
    A = 1
    B = 2
    C = 3

class Object1:
    key: Literal[Key.A]

class Object2:
    @property
    def key(self) -> Literal[Key.A]: ...

class Object3:
    @property
    def key(self) -> Literal[Key.B]: ...

x: Union[Object1, Object2, Object3]
if x.key is Key.A:
    reveal_type(x)  # N: Revealed type is "__main__.Object1 | __main__.Object2"
else:
    reveal_type(x)  # N: Revealed type is "__main__.Object3"
[builtins fixtures/property.pyi]

[case testNarrowingParentWithAny]
# flags: --strict-equality --warn-unreachable
from enum import Enum
from typing import Literal, Union, Any

class Key(Enum):
    A = 1
    B = 2
    C = 3

class Object1:
    key: Literal[Key.A]

class Object2:
    key: Literal[Key.B]

x: Union[Object1, Object2, Any]
if x.key is Key.A:
    reveal_type(x.key)  # N: Revealed type is "Literal[__main__.Key.A]"
    reveal_type(x)      # N: Revealed type is "__main__.Object1 | Any"
else:
    # TODO: Is this a bug? Should we skip inferring Any for singleton types?
    reveal_type(x.key)  # N: Revealed type is "Any | Literal[__main__.Key.B]"
    reveal_type(x)      # N: Revealed type is "__main__.Object1 | __main__.Object2 | Any"
[builtins fixtures/tuple.pyi]

[case testNarrowingParentsHierarchy]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Union
from enum import Enum

class Key(Enum):
    A = 1
    B = 2
    C = 3

class Parent1:
    child: Union[Child1, Child2]
class Parent2:
    child: Union[Child2, Child3]
class Parent3:
    child: Union[Child3, Child1]

class Child1:
    main: Literal[Key.A]
    same_for_1_and_2: Literal[Key.A]
class Child2:
    main: Literal[Key.B]
    same_for_1_and_2: Literal[Key.A]
class Child3:
    main: Literal[Key.C]
    same_for_1_and_2: Literal[Key.B]

x: Union[Parent1, Parent2, Parent3]
if x.child.main is Key.A:
    reveal_type(x)          # N: Revealed type is "__main__.Parent1 | __main__.Parent3"
    reveal_type(x.child)    # N: Revealed type is "__main__.Child1"
else:
    reveal_type(x)          # N: Revealed type is "__main__.Parent1 | __main__.Parent2 | __main__.Parent3"
    reveal_type(x.child)    # N: Revealed type is "__main__.Child2 | __main__.Child3"

if x.child.same_for_1_and_2 is Key.A:
    reveal_type(x)          # N: Revealed type is "__main__.Parent1 | __main__.Parent2 | __main__.Parent3"
    reveal_type(x.child)    # N: Revealed type is "__main__.Child1 | __main__.Child2"
else:
    reveal_type(x)          # N: Revealed type is "__main__.Parent2 | __main__.Parent3"
    reveal_type(x.child)    # N: Revealed type is "__main__.Child3"

y: Union[Parent1, Parent2]
if y.child.main is Key.A:
    reveal_type(y)          # N: Revealed type is "__main__.Parent1"
    reveal_type(y.child)    # N: Revealed type is "__main__.Child1"
else:
    reveal_type(y)          # N: Revealed type is "__main__.Parent1 | __main__.Parent2"
    reveal_type(y.child)    # N: Revealed type is "__main__.Child2 | __main__.Child3"

if y.child.same_for_1_and_2 is Key.A:
    reveal_type(y)          # N: Revealed type is "__main__.Parent1 | __main__.Parent2"
    reveal_type(y.child)    # N: Revealed type is "__main__.Child1 | __main__.Child2"
else:
    reveal_type(y)          # N: Revealed type is "__main__.Parent2"
    reveal_type(y.child)    # N: Revealed type is "__main__.Child3"
[builtins fixtures/tuple.pyi]

[case testNarrowingParentsHierarchyGenerics]
# flags: --strict-equality --warn-unreachable
from typing import Generic, TypeVar, Union

T = TypeVar('T')
class Model(Generic[T]):
    attr: T
class A:
    model: Model[int]
class B:
    model: Model[str]

x: Union[A, B]
if isinstance(x.model.attr, int):
    reveal_type(x)          # N: Revealed type is "__main__.A"
    reveal_type(x.model)    # N: Revealed type is "__main__.Model[builtins.int]"
else:
    reveal_type(x)          # N: Revealed type is "__main__.B"
    reveal_type(x.model)    # N: Revealed type is "__main__.Model[builtins.str]"
[builtins fixtures/isinstance.pyi]

[case testNarrowingParentsHierarchyTypedDict]
# flags: --strict-equality --warn-unreachable
from typing import Literal, TypedDict, Union
from enum import Enum

class Key(Enum):
    A = 1
    B = 2
    C = 3

class Parent1(TypedDict):
    model: Model1
    foo: int

class Parent2(TypedDict):
    model: Model2
    bar: str

class Model1(TypedDict):
    key: Literal[Key.A]

class Model2(TypedDict):
    key: Literal[Key.B]

x: Union[Parent1, Parent2]
if x["model"]["key"] is Key.A:
    reveal_type(x)              # N: Revealed type is "TypedDict('__main__.Parent1', {'model': TypedDict('__main__.Model1', {'key': Literal[__main__.Key.A]}), 'foo': builtins.int})"
    reveal_type(x["model"])     # N: Revealed type is "TypedDict('__main__.Model1', {'key': Literal[__main__.Key.A]})"
else:
    reveal_type(x)              # N: Revealed type is "TypedDict('__main__.Parent2', {'model': TypedDict('__main__.Model2', {'key': Literal[__main__.Key.B]}), 'bar': builtins.str})"
    reveal_type(x["model"])     # N: Revealed type is "TypedDict('__main__.Model2', {'key': Literal[__main__.Key.B]})"

y: Union[Parent1, Parent2]
if y["model"]["key"] is Key.C:  # E: Non-overlapping identity check (left operand type: "Literal[Key.A, Key.B]", right operand type: "Literal[Key.C]")
    reveal_type(y)              # E: Statement is unreachable
    reveal_type(y["model"])
else:
    reveal_type(y)              # N: Revealed type is "TypedDict('__main__.Parent1', {'model': TypedDict('__main__.Model1', {'key': Literal[__main__.Key.A]}), 'foo': builtins.int}) | TypedDict('__main__.Parent2', {'model': TypedDict('__main__.Model2', {'key': Literal[__main__.Key.B]}), 'bar': builtins.str})"
    reveal_type(y["model"])     # N: Revealed type is "TypedDict('__main__.Model1', {'key': Literal[__main__.Key.A]}) | TypedDict('__main__.Model2', {'key': Literal[__main__.Key.B]})"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingParentsHierarchyTypedDictWithStr]
# flags: --strict-equality --warn-unreachable
from typing import Literal, TypedDict, Union

class Parent1(TypedDict):
    model: Model1
    foo: int

class Parent2(TypedDict):
    model: Model2
    bar: str

class Model1(TypedDict):
    key: Literal['A']

class Model2(TypedDict):
    key: Literal['B']

x: Union[Parent1, Parent2]
if x["model"]["key"] == 'A':
    reveal_type(x)              # N: Revealed type is "TypedDict('__main__.Parent1', {'model': TypedDict('__main__.Model1', {'key': Literal['A']}), 'foo': builtins.int})"
    reveal_type(x["model"])     # N: Revealed type is "TypedDict('__main__.Model1', {'key': Literal['A']})"
else:
    reveal_type(x)              # N: Revealed type is "TypedDict('__main__.Parent2', {'model': TypedDict('__main__.Model2', {'key': Literal['B']}), 'bar': builtins.str})"
    reveal_type(x["model"])     # N: Revealed type is "TypedDict('__main__.Model2', {'key': Literal['B']})"

y: Union[Parent1, Parent2]
if y["model"]["key"] == 'C':  # E: Non-overlapping equality check (left operand type: "Literal['A', 'B']", right operand type: "Literal['C']")
    reveal_type(y)              # E: Statement is unreachable
    reveal_type(y["model"])
else:
    reveal_type(y)              # N: Revealed type is "TypedDict('__main__.Parent1', {'model': TypedDict('__main__.Model1', {'key': Literal['A']}), 'foo': builtins.int}) | TypedDict('__main__.Parent2', {'model': TypedDict('__main__.Model2', {'key': Literal['B']}), 'bar': builtins.str})"
    reveal_type(y["model"])     # N: Revealed type is "TypedDict('__main__.Model1', {'key': Literal['A']}) | TypedDict('__main__.Model2', {'key': Literal['B']})"
[builtins fixtures/primitives.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingExprPropagation]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Union

class A:
    tag: Literal['A']

class B:
    tag: Literal['B']

abo: Union[A, B, None]

if abo is not None and abo.tag == "A":
    reveal_type(abo.tag) # N: Revealed type is "Literal['A']"
    reveal_type(abo) # N: Revealed type is "__main__.A"

if not (abo is None or abo.tag != "B"):
    reveal_type(abo.tag) # N: Revealed type is "Literal['B']"
    reveal_type(abo) # N: Revealed type is "__main__.B"
[builtins fixtures/primitives.pyi]

[case testNarrowingEqualityFlipFlop]
# flags: --strict-equality --warn-unreachable
from typing import Final, Literal
from enum import Enum

class State(Enum):
    A = 1
    B = 2

class FlipFlopEnum:
    def __init__(self) -> None:
        self.state = State.A

    def mutate(self) -> None:
        self.state = State.B if self.state == State.A else State.A

class FlipFlopStr:
    def __init__(self) -> None:
        self.state = "state-1"

    def mutate(self) -> None:
        self.state = "state-2" if self.state == "state-1" else "state-1"


def test1(switch: FlipFlopStr) -> None:
    # Naively, we might assume the 'assert' here would narrow the type to
    # Literal["state-1"]. However, doing this ends up breaking a fair number of real-world
    # code (usually test cases) that looks similar to this function: e.g. checks
    # to make sure a field was mutated to some particular value.
    #
    # And since mypy can't really reason about state mutation, we take a conservative
    # approach and avoid narrowing anything here.

    assert switch.state == "state-1"
    reveal_type(switch.state)          # N: Revealed type is "builtins.str"

    switch.mutate()

    assert switch.state == "state-2"
    reveal_type(switch.state)          # N: Revealed type is "builtins.str"

def test2(switch: FlipFlopEnum) -> None:
    # This is the same thing as 'test1', except we use enums, which we allow to be narrowed
    # to literals.

    assert switch.state == State.A
    reveal_type(switch.state)          # N: Revealed type is "Literal[__main__.State.A]"

    switch.mutate()

    assert switch.state == State.B     # E: Non-overlapping equality check (left operand type: "Literal[State.A]", right operand type: "Literal[State.B]")
    reveal_type(switch.state)          # E: Statement is unreachable

def test3(switch: FlipFlopEnum) -> None:
    # Same thing, but using 'is' comparisons. Previously mypy's behaviour differed
    # here, narrowing when using 'is', but not when using '=='.

    assert switch.state is State.A
    reveal_type(switch.state)          # N: Revealed type is "Literal[__main__.State.A]"

    switch.mutate()

    assert switch.state is State.B     # E: Non-overlapping identity check (left operand type: "Literal[State.A]", right operand type: "Literal[State.B]")
    reveal_type(switch.state)          # E: Statement is unreachable
[builtins fixtures/primitives.pyi]

[case testNarrowingEqualityRequiresExplicitStrLiteral]
# flags: --strict-equality --warn-unreachable
from typing import Final, Literal

A_final: Final = "A"
A_literal: Literal["A"]

# Neither the LHS nor the RHS are explicit literals, so regrettably nothing
# is narrowed here -- see 'testNarrowingEqualityFlipFlop' for an example of
# why more precise inference here is problematic.
x_str: str
if x_str == "A":
    reveal_type(x_str)  # N: Revealed type is "builtins.str"
else:
    reveal_type(x_str)  # N: Revealed type is "builtins.str"
reveal_type(x_str)      # N: Revealed type is "builtins.str"

if x_str == A_final:
    reveal_type(x_str)  # N: Revealed type is "builtins.str"
else:
    reveal_type(x_str)  # N: Revealed type is "builtins.str"
reveal_type(x_str)      # N: Revealed type is "builtins.str"

# But the RHS is a literal, so we can at least narrow the 'if' case now.
if x_str == A_literal:
    reveal_type(x_str)  # N: Revealed type is "Literal['A']"
else:
    reveal_type(x_str)  # N: Revealed type is "builtins.str"
reveal_type(x_str)      # N: Revealed type is "builtins.str"

# But in these two cases, the LHS is a literal/literal-like type. So we
# assume the user *does* want literal-based narrowing and narrow accordingly
# regardless of whether the RHS is an explicit literal or not.
x_union: Literal["A", "B", None]
if x_union == A_final:
    reveal_type(x_union)  # N: Revealed type is "Literal['A']"
else:
    reveal_type(x_union)  # N: Revealed type is "Literal['B'] | None"
reveal_type(x_union)      # N: Revealed type is "Literal['A'] | Literal['B'] | None"

if x_union == A_literal:
    reveal_type(x_union)  # N: Revealed type is "Literal['A']"
else:
    reveal_type(x_union)  # N: Revealed type is "Literal['B'] | None"
reveal_type(x_union)      # N: Revealed type is "Literal['A'] | Literal['B'] | None"
[builtins fixtures/primitives.pyi]

[case testNarrowingEqualityRequiresExplicitEnumLiteral]
# flags: --strict-equality --warn-unreachable
from typing import Final, Literal, Union
from enum import Enum

class Foo(Enum):
    A = 1
    B = 2

A_final: Final = Foo.A
A_literal: Literal[Foo.A]

# Note this is unlike testNarrowingEqualityRequiresExplicitStrLiteral
# See also testNarrowingEqualityFlipFlop
x1: Foo
if x1 == Foo.A:
    reveal_type(x1)  # N: Revealed type is "Literal[__main__.Foo.A]"
else:
    reveal_type(x1)  # N: Revealed type is "Literal[__main__.Foo.B]"

x2: Foo
if x2 == A_final:
    reveal_type(x2)  # N: Revealed type is "Literal[__main__.Foo.A]"
else:
    reveal_type(x2)  # N: Revealed type is "Literal[__main__.Foo.B]"

# But we let this narrow since there's an explicit literal in the RHS.
x3: Foo
if x3 == A_literal:
    reveal_type(x3)  # N: Revealed type is "Literal[__main__.Foo.A]"
else:
    reveal_type(x3)  # N: Revealed type is "Literal[__main__.Foo.B]"


class SingletonFoo(Enum):
    A = "A"

def bar(x: Union[SingletonFoo, Foo], y: SingletonFoo) -> None:
    if x == y:
        reveal_type(x)  # N: Revealed type is "Literal[__main__.SingletonFoo.A]"
[builtins fixtures/primitives.pyi]

[case testNarrowingEqualityCustomEqualityDisabled]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Union

class Custom:
    def __eq__(self, other: object) -> bool: return True

def f1(x: Union[Custom, Literal[1], Literal[2]]):
    if x == 1:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | Literal[1]"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | Literal[2]"

class Default: pass

def f2(x: Union[Default, Literal[1], Literal[2]]):
    if x == 1:
        reveal_type(x)  # N: Revealed type is "Literal[1]"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Default | Literal[2]"
[builtins fixtures/primitives.pyi]

[case testNarrowingEqualityCustomEqualityEnum]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Union
from enum import Enum

class CustomEnum(Enum):
    A = 1
    B = 2

    def __eq__(self, other: object) -> bool: return True

x3: CustomEnum
key: Literal[CustomEnum.A]
if x3 == key:
    reveal_type(x3)  # N: Revealed type is "__main__.CustomEnum"
else:
    reveal_type(x3)  # N: Revealed type is "Literal[__main__.CustomEnum.B]"

# For comparison, this narrows since we bypass __eq__
if x3 is key:
    reveal_type(x3)  # N: Revealed type is "Literal[__main__.CustomEnum.A]"
else:
    reveal_type(x3)  # N: Revealed type is "Literal[__main__.CustomEnum.B]"
[builtins fixtures/primitives.pyi]

[case testNarrowingEqualityCustomEqualityChainedComparison]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Union

class Custom:
    def __eq__(self, other: object) -> bool: return True

def f1(x: Literal[1, 2, None], y: Custom):
    if 1 == x == y:
        reveal_type(x)   # N: Revealed type is "Literal[1]"
        reveal_type(y)   # N: Revealed type is "__main__.Custom"
    else:
        reveal_type(x)   # N: Revealed type is "Literal[1] | Literal[2] | None"
        reveal_type(y)   # N: Revealed type is "__main__.Custom"

class Default: pass

def f2(x: Literal[1, 2, None], z: Default):
    if 1 == x == z:      # E: Non-overlapping equality check (left operand type: "Literal[1, 2] | None", right operand type: "Default")
        reveal_type(x)   # E: Statement is unreachable
        reveal_type(z)
    else:
        reveal_type(x)   # N: Revealed type is "Literal[1] | Literal[2] | None"
        reveal_type(z)   # N: Revealed type is "__main__.Default"
[builtins fixtures/primitives.pyi]

[case testNarrowingCustomEqualityLiteralElseBranch]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Literal

class Custom:
    def __eq__(self, other: object) -> bool:
        raise

def f(v: Custom | Literal["text"]) -> Custom | None:
    if v == "text":
        reveal_type(v)  # N: Revealed type is "__main__.Custom | Literal['text']"
        return None
    else:
        reveal_type(v)  # N: Revealed type is "__main__.Custom"
        return v

def g(v: Custom | Literal["text"]) -> Custom | None:
    if v != "text":
        reveal_type(v)  # N: Revealed type is "__main__.Custom"
        return None
    else:
        reveal_type(v)  # N: Revealed type is "__main__.Custom | Literal['text']"
        return v  # E: Incompatible return value type (got "Custom | Literal['text']", expected "Custom | None")
[builtins fixtures/primitives.pyi]

[case testNarrowingCustomEqualityUnion]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Any

def realistic(x: dict[str, Any]):
    val = x.get("hey")
    if val == 12:
        reveal_type(val)  # N: Revealed type is "Any | Literal[12]?"

def f1(x: Any | None):
    if x == 12:
        reveal_type(x)  # N: Revealed type is "Any | Literal[12]?"

class Custom:
    def __eq__(self, other: object) -> bool:
        raise

def f2(x: Custom | None):
    if x == 12:
        reveal_type(x)  # N: Revealed type is "__main__.Custom"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | None"
[builtins fixtures/dict.pyi]

[case testNarrowingCustomEqualityUnion2]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Any

class Custom:
    def __eq__(self, other: object) -> bool:
        raise

def f3(x: str | Custom, y: str | int):
    if x == y:
        reveal_type(x)  # N: Revealed type is "builtins.str | __main__.Custom"
        reveal_type(y)  # N: Revealed type is "builtins.str | builtins.int"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.str | __main__.Custom"
        reveal_type(y)  # N: Revealed type is "builtins.str | builtins.int"

def f4(x: str | Any, y: str | int):
    if x == y:
        reveal_type(x)  # N: Revealed type is "builtins.str | Any | builtins.int"
        reveal_type(y)  # N: Revealed type is "builtins.str | builtins.int"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.str | Any"
        reveal_type(y)  # N: Revealed type is "builtins.str | builtins.int"
[builtins fixtures/dict.pyi]

[case testNarrowingCustomEqualityUnion3]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Any

class Custom:
    def __eq__(self, other: object) -> bool:
        raise

def f(x: Custom | None, y: int | None):
    if x == y:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | None"
        reveal_type(y)  # N: Revealed type is "builtins.int | None"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | None"
        reveal_type(y)  # N: Revealed type is "builtins.int | None"
[builtins fixtures/primitives.pyi]

[case testNarrowingCustomEqualityUnion4]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations

class Custom:
    def __eq__(self, other: object) -> bool:
        return True

def f(x: Custom | None, y: Custom):
    if x == y:
        # We unsoundly special case None and narrow x to Custom here
        reveal_type(x)  # N: Revealed type is "__main__.Custom"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | None"
[builtins fixtures/primitives.pyi]

[case testNarrowingCustomEqualityUnion5]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Any

class Custom1:
    def __eq__(self, other: object) -> bool:
        raise

class Custom2:
    def __eq__(self, other: object) -> bool:
        raise

def f(x: Custom1 | int, y: Custom2 | int):
    if x == y:
        reveal_type(x)  # N: Revealed type is "__main__.Custom1 | builtins.int"
        reveal_type(y)  # N: Revealed type is "__main__.Custom2 | builtins.int"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Custom1 | builtins.int"
        reveal_type(y)  # N: Revealed type is "__main__.Custom2 | builtins.int"
[builtins fixtures/primitives.pyi]

[case testNarrowingCustomEqualitySubclass]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Any

class Custom:
    def __eq__(self, other: object) -> bool:
        raise

class CustomSub(Custom):
    def __eq__(self, other: object) -> bool:
        raise

def f(x: Custom, y: CustomSub):
    if x == y:
        reveal_type(x)  # N: Revealed type is "__main__.Custom"
        reveal_type(y)  # N: Revealed type is "__main__.CustomSub"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Custom"
        reveal_type(y)  # N: Revealed type is "__main__.CustomSub"
[builtins fixtures/tuple.pyi]

[case testNarrowingCustomEqualityGeneric]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Union

class Custom:
    def __eq__(self, other: object) -> bool:
        raise

class Default: ...

def f1(x: list[Custom] | Default, y: list[int]):
    if x == y:  # E: Non-overlapping equality check (left operand type: "list[Custom] | Default", right operand type: "list[int]")
        reveal_type(x)  # N: Revealed type is "builtins.list[__main__.Custom]"
        reveal_type(y)  # N: Revealed type is "builtins.list[builtins.int]"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.list[__main__.Custom] | __main__.Default"
        reveal_type(y)  # N: Revealed type is "builtins.list[builtins.int]"

f1([], [])

def f2(x: list[Custom] | Default, y: list[int] | list[Default]):
    if x == y:  # E: Non-overlapping equality check (left operand type: "list[Custom] | Default", right operand type: "list[int] | list[Default]")
        reveal_type(x)  # N: Revealed type is "builtins.list[__main__.Custom]"
        reveal_type(y)  # N: Revealed type is "builtins.list[builtins.int] | builtins.list[__main__.Default]"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.list[__main__.Custom] | __main__.Default"
        reveal_type(y)  # N: Revealed type is "builtins.list[builtins.int] | builtins.list[__main__.Default]"

listcustom_or_default = Union[list[Custom], Default]
listint_or_default = Union[list[int], list[Default]]

def f2_with_alias(x: listcustom_or_default, y: listint_or_default):
    if x == y:  # E: Non-overlapping equality check (left operand type: "list[Custom] | Default", right operand type: "list[int] | list[Default]")
        reveal_type(x)  # N: Revealed type is "builtins.list[__main__.Custom]"
        reveal_type(y)  # N: Revealed type is "builtins.list[builtins.int] | builtins.list[__main__.Default]"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.list[__main__.Custom] | __main__.Default"
        reveal_type(y)  # N: Revealed type is "builtins.list[builtins.int] | builtins.list[__main__.Default]"

def f3(x: Custom | dict[str, str], y: dict[int, int]):
    if x == y:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | builtins.dict[builtins.str, builtins.str]"
        reveal_type(y)  # N: Revealed type is "builtins.dict[builtins.int, builtins.int]"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | builtins.dict[builtins.str, builtins.str]"
        reveal_type(y)  # N: Revealed type is "builtins.dict[builtins.int, builtins.int]"
[builtins fixtures/primitives.pyi]

[case testNarrowingRecursiveCallable]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Callable

class A: ...
class B: ...

T = Callable[[A], "S"]
S = Callable[[B], "T"]

def f(x: S, y: T):
    if x == y:  # E: Unsupported left operand type for == ("Callable[[B], T]")
        reveal_type(x)  # E: Statement is unreachable
        reveal_type(y)
    else:
        reveal_type(x)  # N: Revealed type is "def (__main__.B) -> def (__main__.A) -> ..."
        reveal_type(y)  # N: Revealed type is "def (__main__.A) -> def (__main__.B) -> ..."
[builtins fixtures/tuple.pyi]

[case testNarrowingRecursiveUnion]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Union

class A: ...
class B: ...

T = Union[A, "S"]
S = Union[B, "T"]  # E: Invalid recursive alias: a union item of itself

def f(x: S, y: T):
    if x == y:
        reveal_type(x)  # N: Revealed type is "Any"
        reveal_type(y)  # N: Revealed type is "__main__.A | Any"
[builtins fixtures/tuple.pyi]

[case testNarrowingUnreachableCases]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Union

a: Literal[1]
b: Literal[1, 2]
c: Literal[2, 3]

if a == b == c:
    reveal_type(a)  # E: Statement is unreachable
    reveal_type(b)
    reveal_type(c)
else:
    reveal_type(a)  # N: Revealed type is "Literal[1]"
    reveal_type(b)  # N: Revealed type is "Literal[1] | Literal[2]"
    reveal_type(c)  # N: Revealed type is "Literal[2] | Literal[3]"

if a == a == a:
    reveal_type(a)  # N: Revealed type is "Literal[1]"
else:
    reveal_type(a)  # E: Statement is unreachable

if a == a == b:
    reveal_type(a)  # N: Revealed type is "Literal[1]"
    reveal_type(b)  # N: Revealed type is "Literal[1]"
else:
    reveal_type(a)  # N: Revealed type is "Literal[1]"
    reveal_type(b)  # N: Revealed type is "Literal[2]"

# In this case, it's ok for 'b' to narrow down to Literal[1] in the else case
# since that's the only way 'b == 2' can be false
if b == 2:
    reveal_type(b)  # N: Revealed type is "Literal[2]"
else:
    reveal_type(b)  # N: Revealed type is "Literal[1]"

# But in this case, we can't conclude anything about the else case. This expression
# could end up being either '2 == 2 == 3' or '1 == 2 == 2', which means we can't
# conclude anything.
if b == 2 == c:
    reveal_type(b)  # N: Revealed type is "Literal[2]"
    reveal_type(c)  # N: Revealed type is "Literal[2]"
else:
    reveal_type(b)  # N: Revealed type is "Literal[1] | Literal[2]"
    reveal_type(c)  # N: Revealed type is "Literal[2] | Literal[3]"
[builtins fixtures/primitives.pyi]

[case testNarrowingUnreachableCases2]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Union

a: Literal[1, 2, 3, 4]
b: Literal[1, 2, 3, 4]

if a == b == 1:
    reveal_type(a)  # N: Revealed type is "Literal[1]"
    reveal_type(b)  # N: Revealed type is "Literal[1]"
elif a == b == 2:
    reveal_type(a)  # N: Revealed type is "Literal[2]"
    reveal_type(b)  # N: Revealed type is "Literal[2]"
elif a == b == 3:
    reveal_type(a)  # N: Revealed type is "Literal[3]"
    reveal_type(b)  # N: Revealed type is "Literal[3]"
elif a == b == 4:
    reveal_type(a)  # N: Revealed type is "Literal[4]"
    reveal_type(b)  # N: Revealed type is "Literal[4]"
else:
    # This branch is reachable if a == 1 and b == 2, for example.
    reveal_type(a)  # N: Revealed type is "Literal[1] | Literal[2] | Literal[3] | Literal[4]"
    reveal_type(b)  # N: Revealed type is "Literal[1] | Literal[2] | Literal[3] | Literal[4]"

if a == a == 1:
    reveal_type(a)  # N: Revealed type is "Literal[1]"
elif a == a == 2:
    reveal_type(a)  # N: Revealed type is "Literal[2]"
elif a == a == 3:
    reveal_type(a)  # N: Revealed type is "Literal[3]"
elif a == a == 4:
    reveal_type(a)  # N: Revealed type is "Literal[4]"
else:
    # In contrast, this branch must be unreachable: we assume (maybe naively)
    # that 'a' won't be mutated in the middle of the expression.
    reveal_type(a)  # E: Statement is unreachable
    reveal_type(b)
[builtins fixtures/primitives.pyi]

[case testNarrowingLiteralTruthiness]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Union

str_or_false: Union[Literal[False], str]

if str_or_false:
    reveal_type(str_or_false)   # N: Revealed type is "builtins.str"
else:
    reveal_type(str_or_false)   # N: Revealed type is "Literal[False] | Literal['']"

true_or_false: Literal[True, False]

if true_or_false:
    reveal_type(true_or_false)  # N: Revealed type is "Literal[True]"
else:
    reveal_type(true_or_false)  # N: Revealed type is "Literal[False]"
[builtins fixtures/primitives.pyi]

[case testNarrowingFalseyToLiteral]
# flags: --strict-equality --warn-unreachable
from typing import Union

a: str
b: bytes
c: int
d: Union[str, bytes, int]

if not a:
    reveal_type(a)  # N: Revealed type is "Literal['']"
if not b:
    reveal_type(b)  # N: Revealed type is "Literal[b'']"
if not c:
    reveal_type(c)  # N: Revealed type is "Literal[0]"
if not d:
    reveal_type(d)  # N: Revealed type is "Literal[''] | Literal[b''] | Literal[0]"

[case testNarrowingIsInstanceFinalSubclass]
# flags: --strict-equality --warn-unreachable

from typing import final

class N: ...
@final
class F1: ...
@final
class F2: ...

n: N
f1: F1

if isinstance(f1, F1):
    reveal_type(f1)  # N: Revealed type is "__main__.F1"
else:
    reveal_type(f1)  # E: Statement is unreachable

if isinstance(n, F1):  # E: Subclass of "N" and "F1" cannot exist: "F1" is final
    reveal_type(n)  # E: Statement is unreachable
else:
    reveal_type(n)  # N: Revealed type is "__main__.N"

if isinstance(f1, N):  # E: Subclass of "F1" and "N" cannot exist: "F1" is final
    reveal_type(f1)  # E: Statement is unreachable
else:
    reveal_type(f1)  # N: Revealed type is "__main__.F1"

if isinstance(f1, F2):  # E: Subclass of "F1" and "F2" cannot exist: "F1" is final \
                        # E: Subclass of "F1" and "F2" cannot exist: "F2" is final
    reveal_type(f1)  # E: Statement is unreachable
else:
    reveal_type(f1)  # N: Revealed type is "__main__.F1"
[builtins fixtures/isinstance.pyi]


[case testNarrowingIsInstanceFinalSubclassWithUnions]
# flags: --strict-equality --warn-unreachable

from typing import final, Union

class N: ...
@final
class F1: ...
@final
class F2: ...

n_f1: Union[N, F1]
n_f2: Union[N, F2]
f1_f2: Union[F1, F2]

if isinstance(n_f1, F1):
    reveal_type(n_f1)  # N: Revealed type is "__main__.F1"
else:
    reveal_type(n_f1)  # N: Revealed type is "__main__.N"

if isinstance(n_f2, F1):  # E: Subclass of "N" and "F1" cannot exist: "F1" is final \
                          # E: Subclass of "F2" and "F1" cannot exist: "F2" is final \
                          # E: Subclass of "F2" and "F1" cannot exist: "F1" is final
    reveal_type(n_f2)  # E: Statement is unreachable
else:
    reveal_type(n_f2)  # N: Revealed type is "__main__.N | __main__.F2"

if isinstance(f1_f2, F1):
    reveal_type(f1_f2)  # N: Revealed type is "__main__.F1"
else:
    reveal_type(f1_f2)  # N: Revealed type is "__main__.F2"
[builtins fixtures/isinstance.pyi]


[case testNarrowingIsSubclassFinalSubclassWithTypeVar]
# flags: --strict-equality --warn-unreachable

from typing import final, Type, TypeVar

@final
class A: ...
@final
class B: ...

T = TypeVar("T", A, B)

def f(cls: Type[T]) -> T:
    if issubclass(cls, A):
        reveal_type(cls)  # N: Revealed type is "type[__main__.A]"
        x: bool
        if x:
            return A()
        else:
            return B()  # E: Incompatible return value type (got "B", expected "A")
    assert False

reveal_type(f(A))  # N: Revealed type is "__main__.A"
reveal_type(f(B))  # N: Revealed type is "__main__.B"
[builtins fixtures/isinstance.pyi]


[case testNarrowingLiteralIdentityCheck]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Union

str_or_false: Union[Literal[False], str]

if str_or_false is not False:
    reveal_type(str_or_false)   # N: Revealed type is "builtins.str"
else:
    reveal_type(str_or_false)   # N: Revealed type is "Literal[False]"

if str_or_false is False:
    reveal_type(str_or_false)  # N: Revealed type is "Literal[False]"
else:
    reveal_type(str_or_false)  # N: Revealed type is "builtins.str"

str_or_true: Union[Literal[True], str]

if str_or_true is True:
    reveal_type(str_or_true)  # N: Revealed type is "Literal[True]"
else:
    reveal_type(str_or_true)  # N: Revealed type is "builtins.str"

if str_or_true is not True:
    reveal_type(str_or_true)  # N: Revealed type is "builtins.str"
else:
    reveal_type(str_or_true)  # N: Revealed type is "Literal[True]"

str_or_bool_literal: Union[Literal[False], Literal[True], str]

if str_or_bool_literal is not True:
    reveal_type(str_or_bool_literal)  # N: Revealed type is "Literal[False] | builtins.str"
else:
    reveal_type(str_or_bool_literal)  # N: Revealed type is "Literal[True]"

if str_or_bool_literal is not True and str_or_bool_literal is not False:
    reveal_type(str_or_bool_literal)  # N: Revealed type is "builtins.str"
else:
    reveal_type(str_or_bool_literal)  # N: Revealed type is "builtins.bool"
[builtins fixtures/primitives.pyi]

[case testNarrowingBooleanIdentityCheck]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Optional

bool_val: bool

if bool_val is not False:
    reveal_type(bool_val)   # N: Revealed type is "Literal[True]"
else:
    reveal_type(bool_val)   # N: Revealed type is "Literal[False]"

opt_bool_val: Optional[bool]

if opt_bool_val is not None:
    reveal_type(opt_bool_val)   # N: Revealed type is "builtins.bool"

if opt_bool_val is not False:
    reveal_type(opt_bool_val)   # N: Revealed type is "Literal[True] | None"
else:
    reveal_type(opt_bool_val)   # N: Revealed type is "Literal[False]"
[builtins fixtures/primitives.pyi]

[case testNarrowingBooleanTruthiness]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Optional

bool_val: bool

if bool_val:
    reveal_type(bool_val)   # N: Revealed type is "Literal[True]"
else:
    reveal_type(bool_val)   # N: Revealed type is "Literal[False]"
reveal_type(bool_val)  # N: Revealed type is "builtins.bool"

opt_bool_val: Optional[bool]

if opt_bool_val:
    reveal_type(opt_bool_val)   # N: Revealed type is "Literal[True]"
else:
    reveal_type(opt_bool_val)   # N: Revealed type is "Literal[False] | None"
reveal_type(opt_bool_val)   # N: Revealed type is "builtins.bool | None"
[builtins fixtures/primitives.pyi]

[case testNarrowingBooleanBoolOp]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Optional

bool_a: bool
bool_b: bool

if bool_a and bool_b:
   reveal_type(bool_a) # N: Revealed type is "Literal[True]"
   reveal_type(bool_b) # N: Revealed type is "Literal[True]"
else:
   reveal_type(bool_a) # N: Revealed type is "builtins.bool"
   reveal_type(bool_b) # N: Revealed type is "builtins.bool"

if not bool_a or bool_b:
   reveal_type(bool_a) # N: Revealed type is "builtins.bool"
   reveal_type(bool_b) # N: Revealed type is "builtins.bool"
else:
   reveal_type(bool_a) # N: Revealed type is "Literal[True]"
   reveal_type(bool_b) # N: Revealed type is "Literal[False]"

if True and bool_b:
   reveal_type(bool_b) # N: Revealed type is "Literal[True]"

x = True and bool_b
reveal_type(x) # N: Revealed type is "builtins.bool"
[builtins fixtures/primitives.pyi]

[case testNarrowingTypedDictUsingEnumLiteral]
# flags: --strict-equality --warn-unreachable
from typing import Literal, TypedDict, Union
from enum import Enum

class E(Enum):
    FOO = "a"
    BAR = "b"

class Foo(TypedDict):
    tag: Literal[E.FOO]
    x: int

class Bar(TypedDict):
    tag: Literal[E.BAR]
    y: int

def f(d: Union[Foo, Bar]) -> None:
    assert d['tag'] == E.FOO
    d['x']
    reveal_type(d)  # N: Revealed type is "TypedDict('__main__.Foo', {'tag': Literal[__main__.E.FOO], 'x': builtins.int})"
[builtins fixtures/dict.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingUsingMetaclass]
# flags: --strict-equality --warn-unreachable
from typing import Type

class M(type):
    pass

class C: pass

def f(t: Type[C]) -> None:
    if type(t) is M:
        reveal_type(t)  # N: Revealed type is "type[__main__.C]"
    else:
        reveal_type(t)  # N: Revealed type is "type[__main__.C]"
    if type(t) is not M:
        reveal_type(t)  # N: Revealed type is "type[__main__.C]"
    else:
        reveal_type(t)  # N: Revealed type is "type[__main__.C]"
    reveal_type(t)  # N: Revealed type is "type[__main__.C]"

[case testNarrowingUsingTypeVar]
# flags: --strict-equality --warn-unreachable
from typing import Type, TypeVar

class A: pass
class B(A): pass

T = TypeVar("T", bound=A)

def f(t: Type[T], a: A, b: B) -> None:
    if type(a) is t:
        reveal_type(a)  # N: Revealed type is "T`-1"
    else:
        reveal_type(a)  # N: Revealed type is "__main__.A"

    if type(b) is t:
        reveal_type(b)  # N: Revealed type is "T`-1"
    else:
        reveal_type(b)  # N: Revealed type is "__main__.B"

[case testNarrowingNestedUnionOfTypedDicts]
# flags: --strict-equality --warn-unreachable
from typing import Literal, TypedDict, Union

class A(TypedDict):
    tag: Literal["A"]
    a: int

class B(TypedDict):
    tag: Literal["B"]
    b: int

class C(TypedDict):
    tag: Literal["C"]
    c: int

AB = Union[A, B]
ABC = Union[AB, C]
abc: ABC

if abc["tag"] == "A":
    reveal_type(abc) # N: Revealed type is "TypedDict('__main__.A', {'tag': Literal['A'], 'a': builtins.int})"
elif abc["tag"] == "C":
    reveal_type(abc) # N: Revealed type is "TypedDict('__main__.C', {'tag': Literal['C'], 'c': builtins.int})"
else:
    reveal_type(abc) # N: Revealed type is "TypedDict('__main__.B', {'tag': Literal['B'], 'b': builtins.int})"
[builtins fixtures/primitives.pyi]
[typing fixtures/typing-typeddict.pyi]

[case testNarrowingRuntimeCover]
# flags: --strict-equality --warn-unreachable
from typing import Dict, List, Union

def unreachable(x: Union[str, List[str]]) -> None:
    if isinstance(x, str):
        reveal_type(x)  # N: Revealed type is "builtins.str"
    elif isinstance(x, list):
        reveal_type(x)  # N: Revealed type is "builtins.list[builtins.str]"
    else:
        reveal_type(x)  # No output: this branch is unreachable  # E: Statement is unreachable

def all_parts_covered(x: Union[str, List[str], List[int], int]) -> None:
    if isinstance(x, str):
        reveal_type(x)  # N: Revealed type is "builtins.str"
    elif isinstance(x, list):
        reveal_type(x)  # N: Revealed type is "builtins.list[builtins.str] | builtins.list[builtins.int]"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.int"

def two_type_vars(x: Union[str, Dict[str, int], Dict[bool, object], int]) -> None:
    if isinstance(x, str):
        reveal_type(x)  # N: Revealed type is "builtins.str"
    elif isinstance(x, dict):
        reveal_type(x)  # N: Revealed type is "builtins.dict[builtins.str, builtins.int] | builtins.dict[builtins.bool, builtins.object]"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.int"
[builtins fixtures/dict.pyi]


[case testNarrowingWithDef]
# flags: --strict-equality --warn-unreachable
from typing import Callable, Optional

def g() -> None:
    foo: Optional[Callable[[], None]] = None
    if foo is None:
        def foo(): ...
    foo()
[builtins fixtures/dict.pyi]


[case testNarrowingOptionalEqualsNone]
# flags: --strict-equality --warn-unreachable
from typing import Optional

class A: ...

val: Optional[A]

if val == None:
    reveal_type(val)  # N: Revealed type is "None"
else:
    reveal_type(val)  # N: Revealed type is "__main__.A"
if val != None:
    reveal_type(val)  # N: Revealed type is "__main__.A"
else:
    reveal_type(val)  # N: Revealed type is "None"

if val in (None,):
    reveal_type(val)  # N: Revealed type is "None"
else:
    reveal_type(val)  # N: Revealed type is "__main__.A"
if val not in (None,):
    reveal_type(val)  # N: Revealed type is "__main__.A"
else:
    reveal_type(val)  # N: Revealed type is "None"
[builtins fixtures/primitives.pyi]

[case testNarrowingCustomEqualityOptionalEqualsNone]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
class Custom:
    def __eq__(self, other) -> bool: ...

def f(x: Custom | None):
    if x == None:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | None"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Custom"
    if x != None:
        reveal_type(x)  # N: Revealed type is "__main__.Custom"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.Custom | None"
[builtins fixtures/primitives.pyi]

[case testNarrowingWithTupleOfTypes]
# flags: --strict-equality --warn-unreachable
from typing import Tuple, Type

class Base: ...

class Impl1(Base): ...
class Impl2(Base): ...

impls: Tuple[Type[Base], ...] = (Impl1, Impl2)
some: object

if isinstance(some, impls):
    reveal_type(some)  # N: Revealed type is "__main__.Base"
else:
    reveal_type(some)  # N: Revealed type is "builtins.object"

raw: Tuple[type, ...]
if isinstance(some, raw):
    reveal_type(some)  # N: Revealed type is "builtins.object"
else:
    reveal_type(some)  # N: Revealed type is "builtins.object"
[builtins fixtures/dict.pyi]


[case testNarrowingWithTupleOfTypesPy310Plus]
# flags: --python-version 3.10 --strict-equality --warn-unreachable
class Base: ...

class Impl1(Base): ...
class Impl2(Base): ...

some: int | Base

impls: tuple[type[Base], ...] = (Impl1, Impl2)
if isinstance(some, impls):
    reveal_type(some)  # N: Revealed type is "__main__.Base"
else:
    reveal_type(some)  # N: Revealed type is "builtins.int | __main__.Base"

raw: tuple[type, ...]
if isinstance(some, raw):
    reveal_type(some)  # N: Revealed type is "builtins.int | __main__.Base"
else:
    reveal_type(some)  # N: Revealed type is "builtins.int | __main__.Base"
[builtins fixtures/dict.pyi]

[case testNarrowingWithAnyOps]
# flags: --strict-equality --warn-unreachable
from typing import Any

class C: ...
class D(C): ...
tp: Any

c: C
if isinstance(c, tp) or isinstance(c, D):
    reveal_type(c)  # N: Revealed type is "Any | __main__.D"
else:
    reveal_type(c)  # N: Revealed type is "__main__.C"
reveal_type(c)  # N: Revealed type is "__main__.C"

c1: C
if isinstance(c1, tp) and isinstance(c1, D):
    reveal_type(c1)  # N: Revealed type is "Any"
else:
    reveal_type(c1)  # N: Revealed type is "__main__.C"
reveal_type(c1)  # N: Revealed type is "__main__.C"

c2: C
if isinstance(c2, D) or isinstance(c2, tp):
    reveal_type(c2)  # N: Revealed type is "__main__.D | Any"
else:
    reveal_type(c2)  # N: Revealed type is "__main__.C"
reveal_type(c2)  # N: Revealed type is "__main__.C"

c3: C
if isinstance(c3, D) and isinstance(c3, tp):
    reveal_type(c3)  # N: Revealed type is "Any"
else:
    reveal_type(c3)  # N: Revealed type is "__main__.C"
reveal_type(c3)  # N: Revealed type is "__main__.C"

t: Any
if isinstance(t, (list, tuple)) and isinstance(t, tuple):
    reveal_type(t)  # N: Revealed type is "builtins.tuple[Any, ...]"
else:
    reveal_type(t)  # N: Revealed type is "Any"
reveal_type(t)  # N: Revealed type is "Any"
[builtins fixtures/isinstancelist.pyi]

[case testNarrowingAnyUnion]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from unknown import A, AA  # E: Cannot find implementation or library stub for module named "unknown" \
                           # N: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports

class B: ...

def f(x: A | B) -> None:
    if isinstance(x, (AA, B)):
        reveal_type(x)  # N: Revealed type is "Any | __main__.B"
    else:
        reveal_type(x)  # N: Revealed type is "Any"
[builtins fixtures/isinstancelist.pyi]

[case testNarrowingLenItemAndLenCompare]
# flags: --strict-equality --warn-unreachable
from typing import Any

x: Any
if len(x) == x:
    reveal_type(x) # N: Revealed type is "Any"
[builtins fixtures/len.pyi]

[case testNarrowingLenTuple]
# flags: --strict-equality --warn-unreachable
from typing import Tuple, Union

VarTuple = Union[Tuple[int, int], Tuple[int, int, int]]

x: VarTuple
a = b = c = 0
if len(x) == 3:
    a, b, c = x
else:
    a, b = x

if len(x) != 3:
    a, b = x
else:
    a, b, c = x
[builtins fixtures/len.pyi]

[case testNarrowingLenHomogeneousTuple]
# flags: --strict-equality --warn-unreachable
from typing import Tuple

x: Tuple[int, ...]
if len(x) == 3:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int]"
else:
    reveal_type(x) # N: Revealed type is "builtins.tuple[builtins.int, ...]"

if len(x) != 3:
    reveal_type(x) # N: Revealed type is "builtins.tuple[builtins.int, ...]"
else:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingLenTypeUnaffected]
# flags: --strict-equality --warn-unreachable
from typing import Union, List

x: Union[str, List[int]]
if len(x) == 3:
    reveal_type(x) # N: Revealed type is "builtins.str | builtins.list[builtins.int]"
else:
    reveal_type(x) # N: Revealed type is "builtins.str | builtins.list[builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingLenAnyListElseNotAffected]
# flags: --strict-equality --warn-unreachable
from typing import Any

def f(self, value: Any) -> Any:
    if isinstance(value, list) and len(value) == 0:
        reveal_type(value) # N: Revealed type is "builtins.list[Any]"
        return value
    reveal_type(value) # N: Revealed type is "Any"
    return None
[builtins fixtures/len.pyi]

[case testNarrowingLenMultiple]
# flags: --strict-equality --warn-unreachable
from typing import Tuple, Union

VarTuple = Union[Tuple[int, int], Tuple[int, int, int]]

x: VarTuple
y: VarTuple
if len(x) == len(y) == 3:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int]"
    reveal_type(y) # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingLenFinal]
# flags: --strict-equality --warn-unreachable
from typing import Final, Tuple, Union

VarTuple = Union[Tuple[int, int], Tuple[int, int, int]]

x: VarTuple
fin: Final = 3
if len(x) == fin:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingLenGreaterThan]
# flags: --strict-equality --warn-unreachable
from typing import Tuple, Union

VarTuple = Union[Tuple[int], Tuple[int, int], Tuple[int, int, int]]

x: VarTuple
if len(x) > 1:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
else:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int]"

if len(x) < 2:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int]"
else:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"

if len(x) >= 2:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
else:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int]"

if len(x) <= 2:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int] | tuple[builtins.int, builtins.int]"
else:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingLenBothSidesUnionTuples]
# flags: --strict-equality --warn-unreachable
from typing import Tuple, Union

VarTuple = Union[
    Tuple[int],
    Tuple[int, int],
    Tuple[int, int, int],
    Tuple[int, int, int, int],
]

x: VarTuple
if 2 <= len(x) <= 3:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
else:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int] | tuple[builtins.int, builtins.int, builtins.int, builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingLenGreaterThanHomogeneousTupleShort]
# flags: --enable-incomplete-feature=PreciseTupleTypes --strict-equality --warn-unreachable
from typing import Tuple

VarTuple = Tuple[int, ...]

x: VarTuple
if len(x) < 3:
    reveal_type(x) # N: Revealed type is "tuple[()] | tuple[builtins.int] | tuple[builtins.int, builtins.int]"
else:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int, Unpack[builtins.tuple[builtins.int, ...]]]"
reveal_type(x)  # N: Revealed type is "builtins.tuple[builtins.int, ...]"
[builtins fixtures/len.pyi]

[case testNarrowingLenBiggerThanHomogeneousTupleLong]
# flags: --enable-incomplete-feature=PreciseTupleTypes --strict-equality --warn-unreachable
from typing import Tuple

VarTuple = Tuple[int, ...]

x: VarTuple
if len(x) < 30:
    reveal_type(x) # N: Revealed type is "builtins.tuple[builtins.int, ...]"
else:
    reveal_type(x) # N: Revealed type is "builtins.tuple[builtins.int, ...]"
[builtins fixtures/len.pyi]

[case testNarrowingLenBothSidesHomogeneousTuple]
# flags: --enable-incomplete-feature=PreciseTupleTypes --strict-equality --warn-unreachable
from typing import Tuple

x: Tuple[int, ...]
if 1 < len(x) < 4:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
else:
    reveal_type(x) # N: Revealed type is "tuple[()] | tuple[builtins.int] | tuple[builtins.int, builtins.int, builtins.int, builtins.int, Unpack[builtins.tuple[builtins.int, ...]]]"
reveal_type(x)  # N: Revealed type is "builtins.tuple[builtins.int, ...]"
[builtins fixtures/len.pyi]

[case testNarrowingLenUnionTupleUnreachable]
# flags: --strict-equality --warn-unreachable
from typing import Tuple, Union

x: Union[Tuple[int, int], Tuple[int, int, int]]
if len(x) >= 4:
    reveal_type(x) # E: Statement is unreachable
else:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"

if len(x) < 2:
    reveal_type(x) # E: Statement is unreachable
else:
    reveal_type(x) # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingLenMixedTypes]
# flags: --strict-equality --warn-unreachable
from typing import Tuple, List, Union

x: Union[Tuple[int, int], Tuple[int, int, int], List[int]]
a = b = c = 0
if len(x) == 3:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int] | builtins.list[builtins.int]"
    a, b, c = x
else:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int] | builtins.list[builtins.int]"
    a, b = x

if len(x) != 3:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int] | builtins.list[builtins.int]"
    a, b = x
else:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int] | builtins.list[builtins.int]"
    a, b, c = x
[builtins fixtures/len.pyi]

[case testNarrowingLenTypeVarTupleEquals]
# flags: --strict-equality --warn-unreachable
from typing import Tuple
from typing_extensions import TypeVarTuple, Unpack

Ts = TypeVarTuple("Ts")
def foo(x: Tuple[int, Unpack[Ts], str]) -> None:
    if len(x) == 5:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"

    if len(x) != 5:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"
[builtins fixtures/len.pyi]

[case testNarrowingLenTypeVarTupleGreaterThan]
# flags: --strict-equality --warn-unreachable
from typing import Tuple
from typing_extensions import TypeVarTuple, Unpack

Ts = TypeVarTuple("Ts")
def foo(x: Tuple[int, Unpack[Ts], str]) -> None:
    if len(x) > 5:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"
        reveal_type(x[5])  # N: Revealed type is "builtins.object"
        reveal_type(x[-6])  # N: Revealed type is "builtins.object"
        reveal_type(x[-1])  # N: Revealed type is "builtins.str"
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"

    if len(x) < 5:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"
        x[5]  # E: Tuple index out of range \
              # N: Variadic tuple can have length 5
        x[-6]  # E: Tuple index out of range \
               # N: Variadic tuple can have length 5
    x[2]  # E: Tuple index out of range \
          # N: Variadic tuple can have length 2
    x[-3]  # E: Tuple index out of range \
           # N: Variadic tuple can have length 2
[builtins fixtures/len.pyi]

[case testNarrowingLenTypeVarTupleUnreachable]
# flags: --strict-equality --warn-unreachable
from typing import Tuple
from typing_extensions import TypeVarTuple, Unpack

Ts = TypeVarTuple("Ts")
def foo(x: Tuple[int, Unpack[Ts], str]) -> None:
    if len(x) == 1:
        reveal_type(x)  # E: Statement is unreachable
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"

    if len(x) != 1:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"
    else:
        reveal_type(x)  # E: Statement is unreachable

def bar(x: Tuple[int, Unpack[Ts], str]) -> None:
    if len(x) >= 2:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"
    else:
        reveal_type(x)  # E: Statement is unreachable

    if len(x) < 2:
        reveal_type(x)  # E: Statement is unreachable
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[Ts`-1], builtins.str]"
[builtins fixtures/len.pyi]

[case testNarrowingLenVariadicTupleEquals]
# flags: --strict-equality --warn-unreachable
from typing import Tuple
from typing_extensions import Unpack

def foo(x: Tuple[int, Unpack[Tuple[float, ...]], str]) -> None:
    if len(x) == 4:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.float, builtins.float, builtins.str]"
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"

    if len(x) != 4:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.float, builtins.float, builtins.str]"
[builtins fixtures/len.pyi]

[case testNarrowingLenVariadicTupleGreaterThan]
# flags: --strict-equality --warn-unreachable
from typing import Tuple
from typing_extensions import Unpack

def foo(x: Tuple[int, Unpack[Tuple[float, ...]], str]) -> None:
    if len(x) > 3:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.float, builtins.float, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.str] | tuple[builtins.int, builtins.float, builtins.str]"
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"

    if len(x) < 3:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.str]"
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.float, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"
[builtins fixtures/len.pyi]

[case testNarrowingLenVariadicTupleUnreachable]
# flags: --strict-equality --warn-unreachable
from typing import Tuple
from typing_extensions import Unpack

def foo(x: Tuple[int, Unpack[Tuple[float, ...]], str]) -> None:
    if len(x) == 1:
        reveal_type(x)  # E: Statement is unreachable
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"

    if len(x) != 1:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"
    else:
        reveal_type(x)  # E: Statement is unreachable

def bar(x: Tuple[int, Unpack[Tuple[float, ...]], str]) -> None:
    if len(x) >= 2:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"
    else:
        reveal_type(x)  # E: Statement is unreachable

    if len(x) < 2:
        reveal_type(x)  # E: Statement is unreachable
    else:
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.float, ...]], builtins.str]"
[builtins fixtures/len.pyi]

[case testNarrowingLenBareExpressionPrecise]
# flags: --enable-incomplete-feature=PreciseTupleTypes --strict-equality --warn-unreachable
from typing import Tuple

x: Tuple[int, ...]
assert x
reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.int, ...]]]"
[builtins fixtures/len.pyi]

[case testNarrowingLenBareExpressionTypeVarTuple]
# flags: --strict-equality --warn-unreachable
from typing import Tuple
from typing_extensions import TypeVarTuple, Unpack

Ts = TypeVarTuple("Ts")
def test(*xs: Unpack[Ts]) -> None:
    assert xs
    xs[0]  # OK
[builtins fixtures/len.pyi]

[case testNarrowingLenBareExpressionWithNonePrecise]
# flags: --enable-incomplete-feature=PreciseTupleTypes --strict-equality --warn-unreachable
from typing import Tuple, Optional

x: Optional[Tuple[int, ...]]
if x:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, Unpack[builtins.tuple[builtins.int, ...]]]"
else:
    reveal_type(x)  # N: Revealed type is "tuple[()] | None"
[builtins fixtures/len.pyi]

[case testNarrowingLenBareExpressionWithNoneImprecise]
# flags: --strict-equality --warn-unreachable
from typing import Tuple, Optional

x: Optional[Tuple[int, ...]]
if x:
    reveal_type(x)  # N: Revealed type is "builtins.tuple[builtins.int, ...]"
else:
    reveal_type(x)  # N: Revealed type is "builtins.tuple[builtins.int, ...] | None"
[builtins fixtures/len.pyi]

[case testNarrowingLenMixWithAnyPrecise]
# flags: --enable-incomplete-feature=PreciseTupleTypes --strict-equality --warn-unreachable
from typing import Any

x: Any
if isinstance(x, (list, tuple)) and len(x) == 0:
    reveal_type(x)  # N: Revealed type is "tuple[()] | builtins.list[Any]"
else:
    reveal_type(x)  # N: Revealed type is "Any"
reveal_type(x)  # N: Revealed type is "Any"

x1: Any
if isinstance(x1, (list, tuple)) and len(x1) > 1:
    reveal_type(x1)  # N: Revealed type is "tuple[Any, Any, Unpack[builtins.tuple[Any, ...]]] | builtins.list[Any]"
else:
    reveal_type(x1)  # N: Revealed type is "Any"
reveal_type(x1)  # N: Revealed type is "Any"
[builtins fixtures/len.pyi]

[case testNarrowingLenMixWithAnyImprecise]
# flags: --strict-equality --warn-unreachable
from typing import Any

x: Any
if isinstance(x, (list, tuple)) and len(x) == 0:
    reveal_type(x)  # N: Revealed type is "tuple[()] | builtins.list[Any]"
else:
    reveal_type(x)  # N: Revealed type is "Any"
reveal_type(x)  # N: Revealed type is "Any"

x1: Any
if isinstance(x1, (list, tuple)) and len(x1) > 1:
    reveal_type(x1)  # N: Revealed type is "builtins.tuple[Any, ...] | builtins.list[Any]"
else:
    reveal_type(x1)  # N: Revealed type is "Any"
reveal_type(x1)  # N: Revealed type is "Any"
[builtins fixtures/len.pyi]

[case testNarrowingLenExplicitLiteralTypes]
# flags: --strict-equality --warn-unreachable
from typing import Literal, Tuple, Union

VarTuple = Union[
    Tuple[int],
    Tuple[int, int],
    Tuple[int, int, int],
]
x: VarTuple

supported: Literal[2]
if len(x) == supported:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int]"
else:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"

not_supported_yet: Literal[2, 3]
if len(x) == not_supported_yet:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int] | tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
else:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int] | tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingLenUnionOfVariadicTuples]
# flags: --strict-equality --warn-unreachable
from typing import Tuple, Union

x: Union[Tuple[int, ...], Tuple[str, ...]]
if len(x) == 2:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.str, builtins.str]"
else:
    reveal_type(x)  # N: Revealed type is "builtins.tuple[builtins.int, ...] | builtins.tuple[builtins.str, ...]"
[builtins fixtures/len.pyi]

[case testNarrowingLenUnionOfNamedTuples]
# flags: --strict-equality --warn-unreachable
from typing import NamedTuple, Union

class Point2D(NamedTuple):
    x: int
    y: int
class Point3D(NamedTuple):
    x: int
    y: int
    z: int

x: Union[Point2D, Point3D]
if len(x) == 2:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int, fallback=__main__.Point2D]"
else:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int, builtins.int, fallback=__main__.Point3D]"
[builtins fixtures/len.pyi]

[case testNarrowingLenTupleSubclass]
# flags: --strict-equality --warn-unreachable
from typing import Tuple

class Ints(Tuple[int, ...]):
    size: int

x: Ints
if len(x) == 2:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int, fallback=__main__.Ints]"
    reveal_type(x.size)  # N: Revealed type is "builtins.int"
else:
    reveal_type(x)  # N: Revealed type is "__main__.Ints"
    reveal_type(x.size)  # N: Revealed type is "builtins.int"

reveal_type(x)  # N: Revealed type is "__main__.Ints"
[builtins fixtures/len.pyi]

[case testNarrowingLenTupleSubclassCustomNotAllowed]
# flags: --strict-equality --warn-unreachable
from typing import Tuple

class Ints(Tuple[int, ...]):
    def __len__(self) -> int:
        return 0

x: Ints
if len(x) > 2:
    reveal_type(x)  # N: Revealed type is "__main__.Ints"
else:
    reveal_type(x)  # N: Revealed type is "__main__.Ints"
[builtins fixtures/len.pyi]

[case testNarrowingLenTupleSubclassPreciseNotAllowed]
# flags: --enable-incomplete-feature=PreciseTupleTypes --strict-equality --warn-unreachable
from typing import Tuple

class Ints(Tuple[int, ...]):
    size: int

x: Ints
if len(x) > 2:
    reveal_type(x)  # N: Revealed type is "__main__.Ints"
else:
    reveal_type(x)  # N: Revealed type is "__main__.Ints"
[builtins fixtures/len.pyi]

[case testNarrowingLenUnknownLen]
# flags: --strict-equality --warn-unreachable
from typing import Any, Tuple, Union

x: Union[Tuple[int, int], Tuple[int, int, int]]

n: int
if len(x) == n:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
else:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"

a: Any
if len(x) == a:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
else:
    reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int] | tuple[builtins.int, builtins.int, builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingLenUnionWithUnreachable]
# flags: --strict-equality --warn-unreachable
from typing import Union, Sequence

def f(x: Union[int, Sequence[int]]) -> None:
    if (
        isinstance(x, tuple)
        and len(x) == 2
        and isinstance(x[0], int)
        and isinstance(x[1], int)
    ):
        reveal_type(x)  # N: Revealed type is "tuple[builtins.int, builtins.int]"
[builtins fixtures/len.pyi]

[case testNarrowingIsSubclassNoneType1]
# flags: --strict-equality --warn-unreachable
from typing import Type, Union

def f(cls: Type[Union[None, int]]) -> None:
    if issubclass(cls, int):
        reveal_type(cls)  # N: Revealed type is "type[builtins.int]"
    else:
        reveal_type(cls)  # N: Revealed type is "type[None]"
[builtins fixtures/isinstance.pyi]

[case testNarrowingIsSubclassNoneType2]
# flags: --strict-equality --warn-unreachable
from typing import Type, Union

def f(cls: Type[Union[None, int]]) -> None:
    if issubclass(cls, type(None)):
        reveal_type(cls)  # N: Revealed type is "type[None]"
    else:
        reveal_type(cls)  # N: Revealed type is "type[builtins.int]"
[builtins fixtures/isinstance.pyi]

[case testNarrowingIsSubclassNoneType3]
# flags: --strict-equality --warn-unreachable
from typing import Type, Union

NoneType_ = type(None)

def f(cls: Type[Union[None, int]]) -> None:
    if issubclass(cls, NoneType_):
        reveal_type(cls)  # N: Revealed type is "type[None]"
    else:
        reveal_type(cls)  # N: Revealed type is "type[builtins.int]"
[builtins fixtures/isinstance.pyi]

[case testNarrowingIsSubclassNoneType4]
# flags: --python-version 3.10 --strict-equality --warn-unreachable

from types import NoneType
from typing import Type, Union

def f(cls: Type[Union[None, int]]) -> None:
    if issubclass(cls, NoneType):
        reveal_type(cls)  # N: Revealed type is "type[None]"
    else:
        reveal_type(cls)  # N: Revealed type is "type[builtins.int]"
[builtins fixtures/isinstance.pyi]

[case testNarrowingIsInstanceNoIntersectionWithFinalTypeAndNoneType]
# flags: --warn-unreachable --python-version 3.10 --strict-equality

from types import NoneType
from typing import final

class X: ...
class Y: ...
@final
class Z: ...

x: X

if isinstance(x, (Y, Z)):
    reveal_type(x)  # N: Revealed type is "__main__.<subclass of "__main__.X" and "__main__.Y">"
if isinstance(x, (Y, NoneType)):
    reveal_type(x)  # N: Revealed type is "__main__.<subclass of "__main__.X" and "__main__.Y">"
if isinstance(x, (Y, Z, NoneType)):
    reveal_type(x)  # N: Revealed type is "__main__.<subclass of "__main__.X" and "__main__.Y">"
if isinstance(x, (Z, NoneType)):  # E: Subclass of "X" and "Z" cannot exist: "Z" is final \
                                  # E: Subclass of "X" and "NoneType" cannot exist: "NoneType" is final
    reveal_type(x)  # E: Statement is unreachable

[builtins fixtures/isinstance.pyi]

[case testTypeNarrowingReachableNegative]
# flags: --strict-equality --warn-unreachable
from typing import Literal

x: Literal[-1]

if x == -1:
    assert True

[typing fixtures/typing-medium.pyi]
[builtins fixtures/ops.pyi]

[case testTypeNarrowingReachableNegativeUnion]
# flags: --strict-equality --warn-unreachable
from typing import Literal

x: Literal[-1, 1]

if x == -1:
    reveal_type(x)  # N: Revealed type is "Literal[-1]"
else:
    reveal_type(x)  # N: Revealed type is "Literal[1]"

[typing fixtures/typing-medium.pyi]
[builtins fixtures/ops.pyi]

[case testNarrowingWithIntEnum]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Any
from enum import IntEnum

class IE(IntEnum):
    X = 1
    Y = 2

def f1(x: int) -> None:
    if x == IE.X:
        reveal_type(x)  # N: Revealed type is "builtins.int"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.int"
    if x != IE.X:
        reveal_type(x)  # N: Revealed type is "builtins.int"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.int"

def f2(x: IE) -> None:
    if x == 1:
        reveal_type(x)  # N: Revealed type is "__main__.IE"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.IE"

def f3(x: object) -> None:
    if x == IE.X:
        reveal_type(x)  # N: Revealed type is "builtins.object"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.object"

def f4(x: int | Any) -> None:
    if x == IE.X:
        reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.X] | Any"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.int | Any"

def f5(x: int) -> None:
    if x is IE.X:
        reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.X]"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.int"
    if x is not IE.X:
        reveal_type(x)  # N: Revealed type is "builtins.int"
    else:
        reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.X]"

def f6(x: IE) -> None:
     if x == IE.X:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.X]"
     else:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.Y]"
[builtins fixtures/primitives.pyi]

[case testNarrowingWithIntEnum2]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Any
from enum import IntEnum, Enum

class MyDecimal: ...

class IE(IntEnum):
    X = 1
    Y = 2

class IE2(IntEnum):
    X = 1
    Y = 2

class E(Enum):
    X = 1
    Y = 2

def f1(x: IE | MyDecimal) -> None:
     if x == IE.X:
         reveal_type(x)  # N: Revealed type is "__main__.IE | __main__.MyDecimal"
     else:
         reveal_type(x)  # N: Revealed type is "__main__.IE | __main__.MyDecimal"

def f2(x: E | bytes) -> None:
     if x == E.X:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.E.X]"
     else:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.E.Y] | builtins.bytes"

def f3(x: IE | IE2) -> None:
     if x == IE.X:
         reveal_type(x)  # N: Revealed type is "__main__.IE | __main__.IE2"
     else:
         reveal_type(x)  # N: Revealed type is "__main__.IE | __main__.IE2"

def f4(x: IE | E) -> None:
     if x == IE.X:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.X]"
     elif x == E.X:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.E.X]"
     else:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.Y] | Literal[__main__.E.Y]"

def f5(x: E | str | int) -> None:
     if x == E.X:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.E.X]"
     else:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.E.Y] | builtins.str | builtins.int"

def f6(x: IE | Any) -> None:
     if x == IE.X:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.X] | Any"
     else:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.Y] | Any"

def f7(x: IE | None) -> None:
     if x == IE.X:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.X]"
     else:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.Y] | None"

def f8(x: IE | None) -> None:
     if x is None:
         reveal_type(x)  # N: Revealed type is "None"
     elif x == IE.X:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.X]"
     else:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.IE.Y]"
[builtins fixtures/primitives.pyi]

[case testNarrowingWithStrEnum]
# flags: --strict-equality --warn-unreachable
# mypy: strict-equality
from enum import StrEnum

class SE(StrEnum):
    A = 'a'
    B = 'b'

def f1(x: str) -> None:
    if x == SE.A:
        reveal_type(x)  # N: Revealed type is "builtins.str"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.str"

def f2(x: SE) -> None:
    if x == 'a':
        reveal_type(x)  # N: Revealed type is "__main__.SE"
    else:
        reveal_type(x)  # N: Revealed type is "__main__.SE"

def f3(x: object) -> None:
    if x == SE.A:
        reveal_type(x)  # N: Revealed type is "builtins.object"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.object"

def f4(x: SE) -> None:
     if x == SE.A:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.SE.A]"
     else:
         reveal_type(x)  # N: Revealed type is "Literal[__main__.SE.B]"
[builtins fixtures/primitives.pyi]

[case testNarrowingWithEnumStrSubclass]
# flags: --strict-equality --warn-unreachable
from enum import Enum

class ParameterLocation(str, Enum):
    QUERY = "query"
    HEADER = "header"
    PATH = "path"

def foo(location: ParameterLocation):
    if location == "path":
        reveal_type(location)  # N: Revealed type is "__main__.ParameterLocation"
    else:
        reveal_type(location)  # N: Revealed type is "__main__.ParameterLocation"

    if location == ParameterLocation.PATH:
        reveal_type(location)  # N: Revealed type is "Literal[__main__.ParameterLocation.PATH]"
    else:
        reveal_type(location)  # N: Revealed type is "Literal[__main__.ParameterLocation.QUERY] | Literal[__main__.ParameterLocation.HEADER]"
[builtins fixtures/primitives.pyi]

[case testConsistentNarrowingEqAndIn]
# flags: --python-version 3.10 --strict-equality --warn-unreachable

# https://github.com/python/mypy/issues/17864
def f(x: str | int) -> None:
    if x == "x":
        reveal_type(x)  # N: Revealed type is "builtins.str"
        y = x

    if x in ["x"]:
        reveal_type(x)  # N: Revealed type is "builtins.str"
        y = x
        z = x
    z = y
[builtins fixtures/primitives.pyi]

[case testConsistentNarrowingEqAndInWithCustomEq]
# flags: --python-version 3.10 --strict-equality --warn-unreachable

# https://github.com/python/mypy/issues/17864
class C:
    def __init__(self, x: int) -> None:
        self.x = x

    def __eq__(self, other: object) -> bool:
        raise
        # Example implementation:
        # if isinstance(other, C) and other.x == self.x:
        #     return True
        # return NotImplemented

class D(C):
    pass

def f1(x: C) -> None:
    if x in [D(5)]:
        reveal_type(x)  # D  # N: Revealed type is "__main__.C"

f1(C(5))

def f2(x: C) -> None:
    if x == D(5):
        reveal_type(x)  # D  # N: Revealed type is "__main__.C"

f2(C(5))
[builtins fixtures/primitives.pyi]

[case testNarrowingTypeVarNone]
# flags: --strict-equality --warn-unreachable

# https://github.com/python/mypy/issues/18126
from typing import TypeVar

T = TypeVar("T")

def fn_if(arg: T) -> None:
    if arg is None:
        return None
    return None

def fn_while(arg: T) -> None:
    while arg is None:
        return None
    return None
[builtins fixtures/primitives.pyi]

[case testRefinePartialTypeWithinLoop]
# flags: --no-local-partial-types --strict-equality --warn-unreachable

x = None
for _ in range(2):
    if x is not None:
        reveal_type(x)  # N: Revealed type is "builtins.int"
    x = 1
reveal_type(x)  # N: Revealed type is "builtins.int | None"

def f() -> bool: ...

y = None
while f():
    reveal_type(y)  # N: Revealed type is "None | builtins.int"
    y = 1
reveal_type(y)  # N: Revealed type is "builtins.int | None"

z = []  # E: Need type annotation for "z" (hint: "z: list[<type>] = ...")
def g() -> None:
    for i in range(2):
        while f():
            if z:
                z[0] + "v"  # E: Unsupported operand types for + ("int" and "str")
            z.append(1)

class A:
    def g(self) -> None:
        z = []  # E: Need type annotation for "z" (hint: "z: list[<type>] = ...")
        for i in range(2):
            while f():
                if z:
                    z[0] + "v"  # E: Unsupported operand types for + ("int" and "str")
                z.append(1)
[builtins fixtures/primitives.pyi]

[case testPersistentUnreachableLinesNestedInInpersistentUnreachableLines]
# flags: --warn-unreachable --python-version 3.11 --strict-equality

x = None
y = None
while True:
    if x is not None:
        if y is not None:
            reveal_type(y)  # E: Statement is unreachable
    x = 1
[builtins fixtures/bool.pyi]

[case testAvoidFalseRedundantCastInLoops]
# flags: --warn-redundant-casts --strict-equality --warn-unreachable

from typing import Callable, cast, Union

ProcessorReturnValue = Union[str, int]
Processor = Callable[[str], ProcessorReturnValue]

def main_cast(p: Processor) -> None:
    ed: ProcessorReturnValue
    ed = cast(str, ...)
    while True:
        ed = p(cast(str, ed))

def main_no_cast(p: Processor) -> None:
    ed: ProcessorReturnValue
    ed = cast(str, ...)
    while True:
        ed = p(ed)  # E: Argument 1 has incompatible type "str | int"; expected "str"
[builtins fixtures/bool.pyi]

[case testAvoidFalseUnreachableInLoop1]
# flags: --warn-unreachable --python-version 3.11 --strict-equality

def f() -> int | None: ...
def b() -> bool: ...

x: int | None
x = 1
while x is not None or b():
    x = f()
[builtins fixtures/bool.pyi]

[case testAvoidFalseUnreachableInLoop2]
# flags: --warn-unreachable --python-version 3.11 --strict-equality

y = None
while y is None:
    if y is None:
        y = []
    y.append(1)
[builtins fixtures/list.pyi]

[case testAvoidFalseUnreachableInLoop3]
# flags: --warn-unreachable --python-version 3.11 --strict-equality

xs: list[int | None]
y = None
for x in xs:
    if x is not None:
        if y is None:
            y = {}  # E: Need type annotation for "y" (hint: "y: dict[<type>, <type>] = ...")
[builtins fixtures/list.pyi]

[case testAvoidFalseRedundantExprInLoop]
# flags: --enable-error-code redundant-expr --python-version 3.11 --strict-equality --warn-unreachable

def f() -> int | None: ...
def b() -> bool: ...

x: int | None
x = 1
while x is not None and b():
    x = f()
[builtins fixtures/primitives.pyi]

[case testAvoidFalseNonOverlappingEqualityCheckInLoop1]
# flags: --allow-redefinition-new --local-partial-types --strict-equality --warn-unreachable

def f(x: int) -> None:
    while True:
        if x == str():
            break
        x = str()
        if x == int():  # E: Non-overlapping equality check (left operand type: "str", right operand type: "int")
            break  # E: Statement is unreachable
[builtins fixtures/primitives.pyi]

[case testAvoidFalseNonOverlappingEqualityCheckInLoop2]
# flags: --allow-redefinition-new --local-partial-types --strict-equality --warn-unreachable

class A: ...
class B: ...
class C: ...

def f(x: A) -> None:
    while True:
        if x == C():  # E: Non-overlapping equality check (left operand type: "A | B", right operand type: "C")
            break  # E: Statement is unreachable
        x = B()
[builtins fixtures/primitives.pyi]

[case testAvoidFalseNonOverlappingEqualityCheckInLoop3]
# flags: --strict-equality --warn-unreachable

for y in [1.0]:
    if y is not None or y != "None":  # E: Right operand of "or" is never evaluated
        ...

[builtins fixtures/primitives.pyi]

[case testNarrowPromotionsInsideUnions1]
# flags: --strict-equality --warn-unreachable

from typing import Union

x: Union[str, float, None]
y: Union[int, str]
x = y
reveal_type(x)  # N: Revealed type is "builtins.str | builtins.int"
z: Union[complex, str]
z = x
reveal_type(z)  # N: Revealed type is "builtins.int | builtins.str"

[builtins fixtures/primitives.pyi]

[case testNarrowPromotionsInsideUnions2]
# flags: --strict-equality --warn-unreachable

from typing import Optional

def b() -> bool: ...
def i() -> int: ...
x: Optional[float]

while b():
    x = None
    while b():
        reveal_type(x)  # N: Revealed type is "None | builtins.int"
        if x is None or b():
            x = i()
            reveal_type(x)  # N: Revealed type is "builtins.int"

[builtins fixtures/bool.pyi]

[case testAvoidFalseUnreachableInFinally]
# flags: --allow-redefinition-new --local-partial-types --strict-equality --warn-unreachable
def f() -> None:
    try:
        x = 1
        if int():
            x = ""
            return
        if int():
            x = None
            return
    finally:
        reveal_type(x)  # N: Revealed type is "builtins.int | builtins.str | None"
        if isinstance(x, str):
            reveal_type(x)  # N: Revealed type is "builtins.str"
        reveal_type(x) # N: Revealed type is "builtins.int | builtins.str | None"

[builtins fixtures/isinstancelist.pyi]

[case testNarrowingTypeVarMultiple]
# flags: --strict-equality --warn-unreachable
from typing import TypeVar

class A: ...
class B: ...

T = TypeVar("T")
def foo(x: T) -> T:
    if isinstance(x, A):
        pass
    elif isinstance(x, B):
        pass
    else:
        raise
    reveal_type(x)  # N: Revealed type is "T`-1"
    return x
[builtins fixtures/isinstance.pyi]

[case testDoNotNarrowToNever]
# flags: --strict-equality --warn-unreachable
def any():
    return 1

def f() -> None:
    x = "a"
    x = any()
    assert isinstance(x, int)
    reveal_type(x)  # N: Revealed type is "builtins.int"
[builtins fixtures/isinstance.pyi]

[case testNarrowTypeVarBoundType]
# flags: --strict-equality --warn-unreachable
from typing import Type, TypeVar

class A: ...
class B(A):
    other: int

T = TypeVar("T", bound=A)
def test(cls: Type[T]) -> T:
    if issubclass(cls, B):
        reveal_type(cls)  # N: Revealed type is "type[T`-1]"
        reveal_type(cls().other)  # N: Revealed type is "builtins.int"
        return cls()
    return cls()
[builtins fixtures/isinstance.pyi]

[case testNarrowTypeVarBoundUnion]
# flags: --strict-equality --warn-unreachable
from typing import TypeVar

class A:
    x: int
class B:
    x: str

T = TypeVar("T")
def test(x: T) -> T:
    if not isinstance(x, (A, B)):
        return x
    reveal_type(x)  # N: Revealed type is "T`-1"
    reveal_type(x.x)  # N: Revealed type is "builtins.int | builtins.str"
    if isinstance(x, A):
        reveal_type(x)  # N: Revealed type is "T`-1"
        reveal_type(x.x)  # N: Revealed type is "builtins.int"
        return x
    reveal_type(x)  # N: Revealed type is "T`-1"
    reveal_type(x.x)  # N: Revealed type is "builtins.str"
    return x
[builtins fixtures/isinstance.pyi]

[case testIsinstanceNarrowingWithSelfTypes]
# flags: --strict-equality --warn-unreachable
from typing import Generic, TypeVar, overload

T = TypeVar("T")

class A(Generic[T]):
    def __init__(self: A[int]) -> None:
        pass

def check_a(obj: "A[T] | str") -> None:
    reveal_type(obj)  # N: Revealed type is "__main__.A[T`-1] | builtins.str"
    if isinstance(obj, A):
        reveal_type(obj)  # N: Revealed type is "__main__.A[T`-1]"
    else:
        reveal_type(obj)  # N: Revealed type is "builtins.str"


class B(Generic[T]):
    @overload
    def __init__(self, x: T) -> None: ...
    @overload
    def __init__(self: B[int]) -> None: ...
    def __init__(self, x: "T | None" = None) -> None:
        pass

def check_b(obj: "B[T] | str") -> None:
    reveal_type(obj)  # N: Revealed type is "__main__.B[T`-1] | builtins.str"
    if isinstance(obj, B):
        reveal_type(obj)  # N: Revealed type is "__main__.B[T`-1]"
    else:
        reveal_type(obj)  # N: Revealed type is "builtins.str"


class C(Generic[T]):
    @overload
    def __init__(self: C[int]) -> None: ...
    @overload
    def __init__(self, x: T) -> None: ...
    def __init__(self, x: "T | None" = None) -> None:
        pass

def check_c(obj: "C[T] | str") -> None:
    reveal_type(obj)  # N: Revealed type is "__main__.C[T`-1] | builtins.str"
    if isinstance(obj, C):
        reveal_type(obj)  # N: Revealed type is "__main__.C[T`-1]"
    else:
        reveal_type(obj)  # N: Revealed type is "builtins.str"


class D(tuple[T], Generic[T]): ...

def check_d(arg: D[T]) -> None:
    if not isinstance(arg, D):
        return  # E: Statement is unreachable
    reveal_type(arg)  # N: Revealed type is "tuple[T`-1, fallback=__main__.D[Any]]"
[builtins fixtures/tuple.pyi]


[case testNarrowingUnionMixins]
# flags: --strict-equality --warn-unreachable
class Base: ...

class FooMixin:
    def foo(self) -> None: ...

class BarMixin:
    def bar(self) -> None: ...

def baz(item: Base) -> None:
    if not isinstance(item, (FooMixin, BarMixin)):
        raise

    reveal_type(item)  # N: Revealed type is "__main__.<subclass of "__main__.Base" and "__main__.FooMixin"> | __main__.<subclass of "__main__.Base" and "__main__.BarMixin">"
    if isinstance(item, FooMixin):
        reveal_type(item)  # N: Revealed type is "__main__.<subclass of "__main__.Base" and "__main__.FooMixin">"
        item.foo()
    else:
        reveal_type(item)  # N: Revealed type is "__main__.<subclass of "__main__.Base" and "__main__.BarMixin">"
        item.bar()
[builtins fixtures/isinstance.pyi]

[case testCustomSetterNarrowingReWidened]
# flags: --strict-equality --warn-unreachable
class B: ...
class C(B): ...
class C1(B): ...
class D(C): ...

class Test:
    @property
    def foo(self) -> C: ...
    @foo.setter
    def foo(self, val: B) -> None: ...

t: Test
t.foo = D()
reveal_type(t.foo)  # N: Revealed type is "__main__.D"
t.foo = C1()
reveal_type(t.foo)  # N: Revealed type is "__main__.C"
[builtins fixtures/property.pyi]

[case testNarrowingNotImplemented]
# flags: --python-version 3.10 --warn-unreachable
from __future__ import annotations
import types

def foo(x: types.NotImplementedType | str):
    if x is not NotImplemented:
        reveal_type(x)  # N: Revealed type is "builtins.str"

from typing_extensions import Self

class X:
    def __divmod__(self, other: Self | int) -> tuple[Self, Self]: ...

    def __floordiv__(self, other: Self | int) -> Self:
        qr = self.__divmod__(other)
        if qr is NotImplemented:
            return NotImplemented
        return qr[0]
[builtins fixtures/notimplemented.pyi]


[case testNarrowingBooleans]
# flags: --warn-return-any --strict-equality --warn-unreachable
from typing import Any

def foo(x: dict[str, Any]) -> bool:
    if x.get("event") is False:
        return False
    if x.get("event") is True:
        return True
    raise
[builtins fixtures/dict.pyi]


[case testNarrowingTypeObjects]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Callable, Any, TypeVar, Generic, Protocol
_T_co = TypeVar('_T_co', covariant=True)

class Boxxy(Protocol[_T_co]):
    def get_box(self) -> _T_co: ...

class TupleLike(Generic[_T_co]):
    def __init__(self, iterable: Boxxy[_T_co], /) -> None:
        raise

class Box1(Generic[_T_co]):
    def __init__(self, content: _T_co, /) -> None: ...
    def get_box(self) -> _T_co: raise

class Box2(Generic[_T_co]):
    def __init__(self, content: _T_co, /) -> None: ...
    def get_box(self) -> _T_co: raise

def get_type(setting_name: str) -> Callable[[Box1], Any] | type[Any]:
    raise

def main(key: str):
    existing_value_type = get_type(key)
    if existing_value_type is TupleLike:
        reveal_type(TupleLike)  # N: Revealed type is "def [_T_co] (__main__.Boxxy[_T_co`1]) -> __main__.TupleLike[_T_co`1]"
        reveal_type(TupleLike(Box2("str")))  # N: Revealed type is "__main__.TupleLike[builtins.str]"

        reveal_type(existing_value_type)  # N: Revealed type is "(def [_T_co] (__main__.Boxxy[_T_co`1]) -> __main__.TupleLike[_T_co`1]) | type[Any]"
        reveal_type(existing_value_type(Box2("str")))  # N: Revealed type is "__main__.TupleLike[builtins.str] | Any"
[builtins fixtures/tuple.pyi]

[case testNarrowingCollections]
# flags: --strict-equality --warn-unreachable
from typing import cast

class X:
    def __init__(self) -> None:
        self.x: dict[str, str] = {}
        self.y: list[str] = []

    def xxx(self) -> None:
        if self.x == {}:
            reveal_type(self.x)  # N: Revealed type is "builtins.dict[builtins.str, builtins.str]"
            self.x["asdf"]

        if self.x == dict():
            reveal_type(self.x)  # N: Revealed type is "builtins.dict[builtins.str, builtins.str]"
            self.x["asdf"]

        if self.x == cast(dict[int, int], {}):  # E: Non-overlapping equality check (left operand type: "dict[str, str]", right operand type: "dict[int, int]")
            reveal_type(self.x)  # N: Revealed type is "builtins.dict[builtins.str, builtins.str]"
            self.x["asdf"]

    def yyy(self) -> None:
        if self.y == []:
            reveal_type(self.y)  # N: Revealed type is "builtins.list[builtins.str]"
            self.y[0].does_not_exist  # E: "str" has no attribute "does_not_exist"

        if self.y == list():
            reveal_type(self.y)  # N: Revealed type is "builtins.list[builtins.str]"
            self.y[0].does_not_exist  # E: "str" has no attribute "does_not_exist"

        if self.y == cast(list[int], []):  # E: Non-overlapping equality check (left operand type: "list[str]", right operand type: "list[int]")
            reveal_type(self.y)  # N: Revealed type is "builtins.list[builtins.str]"
            self.y[0].does_not_exist  # E: "str" has no attribute "does_not_exist"
[builtins fixtures/dict.pyi]


[case testTypeNarrowingStringInLiteralContainer]
# flags: --strict-equality --warn-unreachable
from typing import Literal

def narrow_tuple(x: str, t: tuple[Literal['a', 'b']]):
    if x in t:
        reveal_type(x)  # N: Revealed type is "Literal['a'] | Literal['b']"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.str"

    if x not in t:
        reveal_type(x)  # N: Revealed type is "builtins.str"
    else:
        reveal_type(x)  # N: Revealed type is "Literal['a'] | Literal['b']"

def narrow_homo_tuple(x: str, t: tuple[Literal['a', 'b'], ...]):
    if x in t:
        reveal_type(x)  # N: Revealed type is "Literal['a'] | Literal['b']"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.str"

def narrow_list(x: str, t: list[Literal['a', 'b']]):
    if x in t:
        reveal_type(x)  # N: Revealed type is "Literal['a'] | Literal['b']"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.str"

def narrow_set(x: str, t: set[Literal['a', 'b']]):
    if x in t:
        reveal_type(x)  # N: Revealed type is "Literal['a'] | Literal['b']"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.str"
[builtins fixtures/primitives.pyi]


[case testNarrowingLiteralInLiteralContainer]
# flags: --strict-equality --warn-unreachable
from typing import Literal

def narrow_tuple(x: Literal['c'], overlap: list[Literal['b', 'c']], no_overlap: list[Literal['a', 'b']]):
    if x in overlap:
        reveal_type(x)  # N: Revealed type is "Literal['c']"
    else:
        reveal_type(x)  # N: Revealed type is "Literal['c']"

    if x in no_overlap:
        reveal_type(x)  # E: Statement is unreachable
    else:
        reveal_type(x)  # N: Revealed type is "Literal['c']"
[builtins fixtures/tuple.pyi]

[case testTypeNarrowingUnionInContainer]
# flags: --strict-equality --warn-unreachable
from typing import Union, Literal

def f1(x: Union[str, float], t1: list[Literal['a', 'b']], t2: list[str]):
    if x in t1:
        reveal_type(x)  # N: Revealed type is "Literal['a'] | Literal['b']"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.str | builtins.float"

    if x in t2:
        reveal_type(x)  # N: Revealed type is "builtins.str"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.str | builtins.float"
[builtins fixtures/primitives.pyi]

[case testNarrowAnyWithEqualityOrContainment]
# flags: --strict-equality --warn-unreachable
# https://github.com/python/mypy/issues/17841
from typing import Any

def f1(x: Any) -> None:
    if x is not None and x not in ["x"]:
        return
    reveal_type(x)  # N: Revealed type is "Any"

def f2(x: Any) -> None:
    if x is not None and x != "x":
        return
    reveal_type(x)  # N: Revealed type is "Any"
[builtins fixtures/tuple.pyi]

[case testNarrowChainedContainment]
# flags: --strict-equality --warn-unreachable

def bad_compare_has_key(has_key: bool, key: str, s: tuple[str, ...]) -> None:
    if has_key == key in s:  # E: Non-overlapping equality check (left operand type: "bool", right operand type: "str")
        reveal_type(has_key)  # E: Statement is unreachable
        reveal_type(key)

def bad_but_should_pass(has_key: bool, key: bool, s: tuple[bool, ...]) -> None:
    if has_key == key in s:
        reveal_type(has_key)  # N: Revealed type is "builtins.bool"
        reveal_type(key)  # N: Revealed type is "builtins.bool"
[builtins fixtures/primitives.pyi]

[case testNarrowChainedComparisonMeetAndForwardPropagation]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Any

def f1(a: str | None, b: str | None) -> None:
    if None is not a == b:
        reveal_type(a)  # N: Revealed type is "builtins.str"
        reveal_type(b)  # N: Revealed type is "builtins.str"

    if (None is not a) and (a == b):
        reveal_type(a)  # N: Revealed type is "builtins.str"
        reveal_type(b)  # N: Revealed type is "builtins.str"

def f2(a: Any | None, b: str | None) -> None:
    if None is not a == b:
        reveal_type(a)  # N: Revealed type is "Any"
        reveal_type(b)  # N: Revealed type is "builtins.str | None"

    if (None is not a) and (a == b):
        reveal_type(a)  # N: Revealed type is "Any"
        reveal_type(b)  # N: Revealed type is "builtins.str | None"

def f3(a: str | None, b: Any | None) -> None:
    if None is not a == b:
        reveal_type(a)  # N: Revealed type is "builtins.str"
        reveal_type(b)  # N: Revealed type is "Any | builtins.str"

    if (None is not a) and (a == b):
        reveal_type(a)  # N: Revealed type is "builtins.str"
        reveal_type(b)  # N: Revealed type is "Any | builtins.str"

def f4(a: str | None, b: str | None, c: str | None) -> None:
    if None is not a == b == c:
        reveal_type(a)  # N: Revealed type is "builtins.str"
        reveal_type(b)  # N: Revealed type is "builtins.str"
        reveal_type(c)  # N: Revealed type is "builtins.str"

    if (None is not a) and (a == b) and (b == c):
        reveal_type(a)  # N: Revealed type is "builtins.str"
        reveal_type(b)  # N: Revealed type is "builtins.str"
        reveal_type(c)  # N: Revealed type is "builtins.str"

def f5(pair: tuple[None, int] | tuple[str, str], other: str | None) -> None:
    if None is not pair[0] == other:
        reveal_type(pair[0])  # N: Revealed type is "builtins.str"
        reveal_type(pair)  # N: Revealed type is "tuple[builtins.str, builtins.str]"
        reveal_type(other)  # N: Revealed type is "builtins.str"

    if (None is not pair[0]) and (pair[0] == other):
        reveal_type(pair[0])  # N: Revealed type is "builtins.str"
        reveal_type(pair)  # N: Revealed type is "tuple[builtins.str, builtins.str]"
        reveal_type(other)  # N: Revealed type is "builtins.str"
[builtins fixtures/primitives.pyi]

[case testNarrowTypeObject]
# flags: --strict-equality --warn-unreachable
from typing import Any

# https://github.com/python/mypy/issues/13704

def f1(cls: type):
    if cls is str:
        reveal_type(cls)  # N: Revealed type is "def (o: builtins.object =) -> builtins.str"
        reveal_type(cls(5))  # N: Revealed type is "builtins.str"

    if issubclass(cls, int):
        reveal_type(cls)  # N: Revealed type is "type[builtins.int]"
    elif cls is str:
        reveal_type(cls)  # N: Revealed type is "def (o: builtins.object =) -> builtins.str"
        reveal_type(cls(5))  # N: Revealed type is "builtins.str"

def f2(cls: type[object]):
    if cls is str:
        reveal_type(cls)  # N: Revealed type is "def (o: builtins.object =) -> builtins.str"
        reveal_type(cls(5))  # N: Revealed type is "builtins.str"

    if issubclass(cls, int):
        reveal_type(cls)  # N: Revealed type is "type[builtins.int]"
    elif cls is str:
        reveal_type(cls)  # N: Revealed type is "def (o: builtins.object =) -> builtins.str"
        reveal_type(cls(5))  # N: Revealed type is "builtins.str"

def f3(cls: type[Any]):
    if cls is str:
        reveal_type(cls)  # N: Revealed type is "type[Any]"
        reveal_type(cls(5))  # N: Revealed type is "Any"

    if issubclass(cls, int):
        reveal_type(cls)  # N: Revealed type is "type[builtins.int]"
    elif cls is str:
        reveal_type(cls)  # N: Revealed type is "type[Any]"
        reveal_type(cls(5))  # N: Revealed type is "Any"
[builtins fixtures/isinstance.pyi]

[case testNarrowTypeObjectUnion]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations

def f4(cls: type[str | int]):
    reveal_type(cls)  # N: Revealed type is "type[builtins.str] | type[builtins.int]"

    if cls is int:
        reveal_type(cls)  # N: Revealed type is "type[builtins.int]"
    if cls == int:
        reveal_type(cls)  # N: Revealed type is "type[builtins.int]"
[builtins fixtures/primitives.pyi]


[case testTypeEqualsCheck]
# flags: --strict-equality --warn-unreachable
from typing import Any

y: Any
if type(y) == int:
    reveal_type(y) # N: Revealed type is "builtins.int"

[case testMultipleTypeEqualsCheck]
# flags: --strict-equality --warn-unreachable
from typing import Any

x: Any
y: Any
if type(x) == type(y) == int:
    reveal_type(y) # N: Revealed type is "builtins.int"
    reveal_type(x) # N: Revealed type is "builtins.int"

z: Any
if int == type(z) == int:
    reveal_type(z) # N: Revealed type is "builtins.int"

[case testTypeEqualsCheckWidening]
# flags: --strict-equality --warn-unreachable
from typing import Any

def f(x: str, y: Any, z: object):
    if type(x) is type(y):
        reveal_type(x) # N: Revealed type is "builtins.str"
        reveal_type(y) # N: Revealed type is "builtins.str"

    if type(x) == type(y):
        reveal_type(x) # N: Revealed type is "builtins.str"
        reveal_type(y) # N: Revealed type is "builtins.str"

    if type(x) is type(z):
        reveal_type(x) # N: Revealed type is "builtins.str"
        reveal_type(z) # N: Revealed type is "builtins.str"

    if type(x) == type(z):
        reveal_type(x) # N: Revealed type is "builtins.str"
        reveal_type(z) # N: Revealed type is "builtins.str"
[builtins fixtures/primitives.pyi]

[case testTypeEqualsCheckUsingIs]
# flags: --strict-equality --warn-unreachable
from typing import Any

y: Any
if type(y) is int:
    reveal_type(y) # N: Revealed type is "builtins.int"

[case testTypeEqualsCheckUsingIsNonOverlapping]
# flags: --strict-equality --warn-unreachable
from typing import Union

y: str
if type(y) is int:  # E: Non-overlapping identity check (left operand type: "type[str]", right operand type: "type[int]") \
                    # E: Subclass of "str" and "int" cannot exist: would have incompatible method signatures
    y  # E: Statement is unreachable
else:
    reveal_type(y) # N: Revealed type is "builtins.str"
[builtins fixtures/isinstance.pyi]

[case testTypeEqualsCheckUsingIsNonOverlappingChild]
# flags: --strict-equality --warn-unreachable
from typing import Union

class A: ...
class B: ...
class C(A): ...
def main(x: Union[B, C]):
    # C instance cannot be exactly its parent A, we need reversed subtyping relationship
    # here (type(parent) is Child).
    if type(x) is A:
        reveal_type(x)  # E: Statement is unreachable
    else:
        reveal_type(x)  # N: Revealed type is "__main__.B | __main__.C"
[builtins fixtures/isinstance.pyi]

[case testTypeEqualsCheckTypeVar]
# flags: --strict-equality --warn-unreachable
from typing import TypeVar

class A: ...
class B: ...

T = TypeVar("T")

def forgets_about_subclasses(self, obj: T) -> T:
    if isinstance(obj, A):
        return A()  # E: Incompatible return value type (got "A", expected "T")
    elif isinstance(obj, B):
        return B()  # E: Incompatible return value type (got "B", expected "T")
    raise

def correct1(self, obj: T) -> T:
    # TODO: mypy should not error in this case
    if type(obj) == A:
        return A()  # E: Incompatible return value type (got "A", expected "T")
    elif type(obj) == B:
        return B()  # E: Incompatible return value type (got "B", expected "T")
    raise

T_value = TypeVar("T_value", A, B)

def forgets_about_multiple_inheritance(self, obj: T_value) -> T_value:
    # Note that it is a little confusing that mypy only errors in the first branch here, but this
    # is a branch that would be taken by a subclass of both A and B.
    # See also https://github.com/python/mypy/issues/10302#issuecomment-3832182574
    if isinstance(obj, A):
        return A()  # E: Incompatible return value type (got "A", expected "B")
    elif isinstance(obj, B):
        return B()
    raise

def correct2(self, obj: T_value) -> T_value:
    if type(obj) == A:
        return A()
    elif type(obj) == B:
        return B()
    raise
[builtins fixtures/primitives.pyi]

[case testTypeEqualsCheckUsingDifferentSpecializedTypes]
# flags: --strict-equality --warn-unreachable
from collections import defaultdict

x: defaultdict
y: dict
z: object
if type(x) is type(y) is type(z):
    reveal_type(x) # N: Revealed type is "collections.defaultdict[Any, Any]"
    reveal_type(y) # N: Revealed type is "collections.defaultdict[Any, Any]"
    reveal_type(z) # N: Revealed type is "collections.defaultdict[Any, Any]"

[case testTypeEqualsTypeObjectUnion]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
def f(x: object, y: type[int] | type[str]):
    if type(x) == y:
        reveal_type(x)  # N: Revealed type is "builtins.int | builtins.str"
        reveal_type(y)  # N: Revealed type is "type[builtins.int] | type[builtins.str]"
[builtins fixtures/primitives.pyi]

[case testUnionTypeEquality]
# flags: --strict-equality --warn-unreachable
from typing import Any, reveal_type

def f(x: Any):
    if type(x) == (int, str):  # E: Non-overlapping equality check (left operand type: "type[Any]", right operand type: "tuple[type[int], type[str]]")
        reveal_type(x) # E: Statement is unreachable
[builtins fixtures/tuple.pyi]

[case testTypeIntersectionWithConcreteTypes]
# flags: --strict-equality --warn-unreachable
class X: x = 1
class Y: y = 1
class Z(X, Y): ...

z = Z()
x: X = z
y: Y = z
if type(x) is type(y):  # E: Non-overlapping identity check (left operand type: "type[X]", right operand type: "type[Y]")
    reveal_type(x)  # N: Revealed type is "__main__.<subclass of "__main__.X" and "__main__.Y">"
    reveal_type(y)  # N: Revealed type is "__main__.<subclass of "__main__.Y" and "__main__.X">"
    x.y + y.x

if isinstance(x, type(y)) and isinstance(y, type(x)):
    reveal_type(x)  # N: Revealed type is "__main__.<subclass of "__main__.X" and "__main__.Y">"
    reveal_type(y)  # N: Revealed type is "__main__.<subclass of "__main__.X" and "__main__.Y">"
    x.y + y.x

[builtins fixtures/isinstance.pyi]

[case testTypeEqualsNarrowingUnionWithElse]
# flags: --strict-equality --warn-unreachable
from typing import Union

x: Union[int, str]
if type(x) is int:
    reveal_type(x)  # N: Revealed type is "builtins.int"
else:
    reveal_type(x)  # N: Revealed type is "builtins.int | builtins.str"

[case testTypeEqualsMultipleTypesShouldntNarrow]
# flags: --strict-equality --warn-unreachable

from typing import Union

x: Union[int, str]
if type(x) == int == str:  # E: Non-overlapping equality check (left operand type: "type[int]", right operand type: "type[str]")
    reveal_type(x)  # E: Statement is unreachable
else:
    reveal_type(x)  # N: Revealed type is "builtins.int | builtins.str"

[builtins fixtures/primitives.pyi]

[case testTypeNotEqualsCheck]
# flags: --strict-equality --warn-unreachable
from typing import Union

x: Union[int, str]
if type(x) != int:
    reveal_type(x)  # N: Revealed type is "builtins.int | builtins.str"
else:
    reveal_type(x)  # N: Revealed type is "builtins.int"

# mypy thinks int isn't defined unless we include this
[builtins fixtures/primitives.pyi]

[case testTypeNotEqualsCheckUsingIsNot]
# flags: --strict-equality --warn-unreachable
from typing import Union

x: Union[int, str]
if type(x) is not int:
    reveal_type(x)  # N: Revealed type is "builtins.int | builtins.str"
else:
    reveal_type(x)  # N: Revealed type is "builtins.int"

[case testTypeNarrowingAgainstType]
# flags: --strict-equality --warn-unreachable
class A:
    def foo(self, x: object) -> None:
        reveal_type(self)  # N: Revealed type is "__main__.A"
        reveal_type(x)  # N: Revealed type is "builtins.object"
        if type(self) is type(x):
            reveal_type(self)  # N: Revealed type is "__main__.A"
            reveal_type(x)  # N: Revealed type is "__main__.A"
        else:
            reveal_type(self)  # N: Revealed type is "__main__.A"
            reveal_type(x)  # N: Revealed type is "builtins.object"
        if type(self) == type(x):
            reveal_type(self)  # N: Revealed type is "__main__.A"
            reveal_type(x)  # N: Revealed type is "__main__.A"
        else:
            reveal_type(self)  # N: Revealed type is "__main__.A"
            reveal_type(x)  # N: Revealed type is "builtins.object"

class B:
    y: int

    def __eq__(self, other: object) -> bool:
        return type(other) is type(self) and other.y == self.y
[builtins fixtures/primitives.pyi]

[case testNarrowInElseCaseIfFinal]
# flags: --strict-equality --warn-unreachable
from typing import final, Union
@final
class C:
    pass
class D:
    pass

x: Union[C, D]
if type(x) is C:
    reveal_type(x)  # N: Revealed type is "__main__.C"
else:
    reveal_type(x)  # N: Revealed type is "__main__.D"

[case testNarrowInIfCaseIfFinalUsingIsNot]
# flags: --strict-equality --warn-unreachable
from typing import final, Union
@final
class C:
    pass
class D:
    pass

x: Union[C, D]
if type(x) is not C:
    reveal_type(x)  # N: Revealed type is "__main__.D"
else:
    reveal_type(x)  # N: Revealed type is "__main__.C"

[case testDunderClassNarrowing]
# flags: --strict-equality --warn-unreachable
from typing import Any

def foo(y: object):
    if y.__class__ == int:
        reveal_type(y) # N: Revealed type is "builtins.int"
    else:
        reveal_type(y) # N: Revealed type is "builtins.object"

    if y.__class__ is int:
        reveal_type(y) # N: Revealed type is "builtins.int"
    else:
        reveal_type(y) # N: Revealed type is "builtins.object"


def bar(y: Any):
    if y.__class__ == int:
        reveal_type(y) # N: Revealed type is "builtins.int"
    else:
        reveal_type(y) # N: Revealed type is "Any"

    if y.__class__ is int:
        reveal_type(y) # N: Revealed type is "builtins.int"
    else:
        reveal_type(y) # N: Revealed type is "Any"
[builtins fixtures/dict-full.pyi]


[case testNarrowTypeVarType]
# flags: --strict-equality --warn-unreachable
from typing import TypeVar

T = TypeVar("T")

class A: ...

def foo(X: type[T]) -> T:
    if X == A:
        return X()
    raise

# It could be nice to make these two test cases consistent, but it would be tricky
# The above case is much more common in real world code
def bar(X: type[T]) -> T:
    if X == A:
        return A()  # E: Incompatible return value type (got "A", expected "T")
    raise
[builtins fixtures/type.pyi]

[case testNarrowingConstrainedTypeVarType]
# flags: --strict-equality --warn-unreachable
from typing import TypeVar, Any, Type

TargetType = TypeVar("TargetType", int, float, str)

# TODO: this behaviour is incorrect, it will be fixed by improving reachability
def convert_type(target_type: Type[TargetType]) -> TargetType:
    if target_type == str:
        return str()
    if target_type == int:
        return int()
    if target_type == float:
        return float()  # E: Incompatible return value type (got "float", expected "int")
    raise


[builtins fixtures/primitives.pyi]


[case testNarrowingEqualityWithPromotions]
# flags: --strict-equality --warn-unreachable
from __future__ import annotations
from typing import Literal

def f1(number: float, i: int):
    if number == i:
        reveal_type(number)  # N: Revealed type is "builtins.float"
        reveal_type(i)  # N: Revealed type is "builtins.int"

def f2(number: float, five: Literal[5]):
    if number == five:
        reveal_type(number)  # N: Revealed type is "builtins.float"
        reveal_type(five)  # N: Revealed type is "Literal[5]"

def f3(number: float | int, five: Literal[5]):
    if number == five:
        reveal_type(number)  # N: Revealed type is "builtins.float | Literal[5]"
        reveal_type(five)  # N: Revealed type is "Literal[5]"

def f8(number: float | Literal[5], five: Literal[5]):
    if number == five:
        reveal_type(number)  # N: Revealed type is "builtins.float | Literal[5]"
        reveal_type(five)  # N: Revealed type is "Literal[5]"
    else:
        reveal_type(number)  # N: Revealed type is "builtins.float"
        reveal_type(five)  # N: Revealed type is "Literal[5]"

def f4(number: float | None, i: int):
    if number == i:
        reveal_type(number)  # N: Revealed type is "builtins.float"
        reveal_type(i)  # N: Revealed type is "builtins.int"

def f5(number: float | int, i: int):
    if number == i:
        reveal_type(number)  # N: Revealed type is "builtins.float | builtins.int"
        reveal_type(i)  # N: Revealed type is "builtins.int"

def f6(number: float | complex, i: int):
    if number == i:
        reveal_type(number)  # N: Revealed type is "builtins.float | builtins.complex"
        reveal_type(i)  # N: Revealed type is "builtins.int"

class Custom:
    def __eq__(self, other: object) -> bool: return True

def f7(number: float, x: Custom | int):
    if number == x:
        reveal_type(number)  # N: Revealed type is "builtins.float"
        reveal_type(x)  # N: Revealed type is "__main__.Custom | builtins.int"
[builtins fixtures/primitives.pyi]

[case testNarrowingAnyNegativeIntersection-xfail]
# flags: --strict-equality --warn-unreachable
# https://github.com/python/mypy/issues/20597
from __future__ import annotations
from typing import Any

class array: ...

def get_result() -> Any: ...

def foo(x: str | array) -> str:
    result = get_result()
    if isinstance(result, array):
        return "asdf"
    if result is x:
        reveal_type(result)  # N: Revealed type is "Any"
        return result
    raise
[builtins fixtures/tuple.pyi]

[case testNarrowingOptionalBytes]
from __future__ import annotations
def f(x: bytes | None):
    if x == b"asdf":
        reveal_type(x)  # N: Revealed type is "builtins.bytes"
    else:
        reveal_type(x)  # N: Revealed type is "builtins.bytes | None"
[builtins fixtures/primitives.pyi]

[case testNarrowingBytesLikeWithPromotion]
# flags: --strict-equality --warn-unreachable --strict-bytes
from __future__ import annotations

def check_test(x: bytes) -> None: ...
check_test(bytearray(b"asdf"))  # E: Argument 1 to "check_test" has incompatible type "bytearray"; expected "bytes"

def main(
    v_bytes: bytes,
    v_bytearray: bytearray,
    v_memoryview: memoryview,
    v_all: bytes | bytearray | memoryview,
) -> None:
    if v_bytes == v_bytearray:
        reveal_type(v_bytes)  # N: Revealed type is "builtins.bytes"
        reveal_type(v_bytearray)  # N: Revealed type is "builtins.bytearray"
    if v_bytes == v_memoryview:
        reveal_type(v_bytes)  # N: Revealed type is "builtins.bytes"
        reveal_type(v_memoryview)  # N: Revealed type is "builtins.memoryview"
    if v_bytearray == v_memoryview:
        reveal_type(v_bytearray)  # N: Revealed type is "builtins.bytearray"
        reveal_type(v_memoryview)  # N: Revealed type is "builtins.memoryview"

    if v_all == v_bytes:
        reveal_type(v_all)  # N: Revealed type is "builtins.bytes"
        reveal_type(v_bytes)  # N: Revealed type is "builtins.bytes"
    if v_all == v_bytearray:
        reveal_type(v_all)  # N: Revealed type is "builtins.bytes | builtins.bytearray | builtins.memoryview"
        reveal_type(v_bytearray)  # N: Revealed type is "builtins.bytearray"
    if v_all == v_memoryview:
        reveal_type(v_all)  # N: Revealed type is "builtins.bytes | builtins.bytearray | builtins.memoryview"
        reveal_type(v_memoryview)  # N: Revealed type is "builtins.memoryview"
[builtins fixtures/primitives.pyi]

[case testNarrowingBytesLikeNoPromotion]
# flags: --strict-equality --warn-unreachable --no-strict-bytes
from __future__ import annotations

def check_test(x: bytes) -> None: ...
check_test(bytearray(b"asdf"))

def main(
    v_bytes: bytes,
    v_bytearray: bytearray,
    v_memoryview: memoryview,
    v_all: bytes | bytearray | memoryview,
) -> None:
    if v_bytes == v_bytearray:
        reveal_type(v_bytes)  # N: Revealed type is "builtins.bytes"
        reveal_type(v_bytearray)  # N: Revealed type is "builtins.bytearray"
    if v_bytes == v_memoryview:
        reveal_type(v_bytes)  # N: Revealed type is "builtins.bytes"
        reveal_type(v_memoryview)  # N: Revealed type is "builtins.memoryview"
    if v_bytearray == v_memoryview:
        reveal_type(v_bytearray)  # N: Revealed type is "builtins.bytearray"
        reveal_type(v_memoryview)  # N: Revealed type is "builtins.memoryview"

    if v_all == v_bytes:
        reveal_type(v_all)  # N: Revealed type is "builtins.bytes | builtins.bytearray | builtins.memoryview"
        reveal_type(v_bytes)  # N: Revealed type is "builtins.bytes"
    if v_all == v_bytearray:
        reveal_type(v_all)  # N: Revealed type is "builtins.bytes | builtins.bytearray | builtins.memoryview"
        reveal_type(v_bytearray)  # N: Revealed type is "builtins.bytearray"
    if v_all == v_memoryview:
        reveal_type(v_all)  # N: Revealed type is "builtins.bytes | builtins.bytearray | builtins.memoryview"
        reveal_type(v_memoryview)  # N: Revealed type is "builtins.memoryview"
[builtins fixtures/primitives.pyi]


[case testNarrowNewTypeVsSubclass]
# mypy: strict-equality, warn-unreachable
from typing import NewType

M1 = NewType("M1", int)
M2 = NewType("M2", int)

def check_m(base: int, m1: M1, m2: M2):
    if m1 == m2:  # E: Non-overlapping equality check (left operand type: "M1", right operand type: "M2")
        reveal_type(m1)  # N: Revealed type is "__main__.M1"
        reveal_type(m2)  # N: Revealed type is "__main__.M2"

    if m1 == base:
        # We do not narrow base
        reveal_type(m1)  # N: Revealed type is "__main__.M1"
        reveal_type(base)  # N: Revealed type is "builtins.int"
        if m2 == base:
            reveal_type(m2)  # N: Revealed type is "__main__.M2"
            reveal_type(base)  # N: Revealed type is "builtins.int"

# We do narrow for subclasses! (assuming no custom equality)
class A: ...
class A1(A): ...
class A2(A): ...

def check_a(base: A, a1: A1, a2: A2):
    if a1 == a2:  # E: Non-overlapping equality check (left operand type: "A1", right operand type: "A2")
        reveal_type(a1)  # E: Statement is unreachable
        reveal_type(a2)

    if a1 == base:
        # We do narrow base
        reveal_type(a1)  # N: Revealed type is "__main__.A1"
        reveal_type(base)  # N: Revealed type is "__main__.A1"
        if a2 == base:  # E: Non-overlapping equality check (left operand type: "A2", right operand type: "A1")
            reveal_type(a2)  # E: Statement is unreachable
            reveal_type(base)
[builtins fixtures/primitives.pyi]


[case testNarrowNewTypeFromObject]
# mypy: strict-equality, warn-unreachable
from __future__ import annotations
from typing import NewType

UserId = NewType("UserId", int)

def f1(whatever: object, uid: UserId):
    # The general principle is that we should not be able to produce a value of NewType
    # without there being explicit wrapping somewhere
    if whatever == uid:
        reveal_type(whatever)  # N: Revealed type is "builtins.int"
        reveal_type(uid)  # N: Revealed type is "__main__.UserId"

class Other: ...

def f2(whatever: object, uid: UserId | Other):
    if whatever == uid:
        reveal_type(whatever)  # N: Revealed type is "builtins.int | __main__.Other"
        reveal_type(uid)  # N: Revealed type is "__main__.UserId | __main__.Other"
[builtins fixtures/primitives.pyi]


[case testNarrowNewTypeNested]
# mypy: strict-equality, warn-unreachable
from typing import NewType, Final

Path = NewType("Path", str)
NormPath = NewType("NormPath", Path)

def op(normpath: NormPath, path: Path):
    if normpath == path:
        # No narrowing
        reveal_type(normpath)  # N: Revealed type is "__main__.NormPath"
        reveal_type(path)  # N: Revealed type is "__main__.Path"
[builtins fixtures/primitives.pyi]


[case testNarrowNewTypeSharedValue]
# mypy: strict-equality, warn-unreachable
from typing import NewType, Final

UserId = NewType("UserId", int)
TeamId = NewType("TeamId", int)
INVALID = 123

def get_owner(uid: UserId, tid: TeamId):
    # No narrowing for INVALID
    if uid == INVALID:
        reveal_type(uid)  # N: Revealed type is "__main__.UserId"
        reveal_type(tid)  # N: Revealed type is "__main__.TeamId"
        reveal_type(INVALID)  # N: Revealed type is "builtins.int"
        if tid == INVALID:
            reveal_type(uid)  # N: Revealed type is "__main__.UserId"
            reveal_type(tid)  # N: Revealed type is "__main__.TeamId"
            reveal_type(INVALID)  # N: Revealed type is "builtins.int"
            return None
[builtins fixtures/primitives.pyi]

[case testNarrowCallableTypeVarByEquality]
from typing import Callable, TypeVar

T = TypeVar("T")

def remove(path: str) -> None: ...
def unlink(path: str) -> None: ...

def f1(func: Callable[..., T], arg: str) -> T:
    if func == remove:
        reveal_type(func)  # N: Revealed type is "def (path: builtins.str) -> T`-1"
        reveal_type(func(arg))  # N: Revealed type is "T`-1"
        return func(arg)
    return func(arg)

def f2(func: Callable[..., T], arg: str) -> T:
    if func in [unlink, remove]:
        reveal_type(func)  # N: Revealed type is "def (path: builtins.str) -> T`-1"
        reveal_type(func(arg))  # N: Revealed type is "T`-1"
        return func(arg)
    return func(arg)
[builtins fixtures/primitives.pyi]