Somehow reveal_type(bool.__new__(bool, Falsy())) is Literal[False] but bool(Falsy()) isn't. Is there some special casing I'm not seeing here?

@Gobot1234 Yes, I think you likely need to add Literal somewhere here

@Gobot1234 Yes, I think you likely need to add Literal somewhere here

mypy/mypy/typeops.py

Lines 195 to 207 in cfd01d9

	if (
	isinstance(explicit_type, (Instance, TupleType, UninhabitedType))
	# We have to skip protocols, because it can be a subtype of a return type
	# by accident. Like `Hashable` is a subtype of `object`. See #11799
	and isinstance(default_ret_type, Instance)
	and not default_ret_type.type.is_protocol
	# Only use the declared return type from __new__ or declared self in __init__
	# if it is actually returning a subtype of what we would return otherwise.
	and is_subtype(explicit_type, default_ret_type, ignore_type_params=True)
	):
	ret_type: Type = explicit_type
	else:
	ret_type = default_ret_type

Thank you, never would have spotted that! Everything should work now

Not entirely sure why CI is failing from my testing this seems to work fine


are the fixtures somehow causing this to fail?

FWIW you are doing something weird with the fixtures. Try placing your updated definitions of bool and int in the fixture, and then add reveal_type()s directly in the test case body (not in [file builtins.py]).

Like this?

[case testOverride__new__WithLiteralReturnPassing]
from typing import Literal

class Falsy:
    def __bool__(self) -> Literal[False]: pass

reveal_type(bool(Falsy()))  # N: Revealed type is "Literal[False]"
reveal_type(int())  # N: Revealed type is "Literal[0]"

[file builtins.py]
from typing import Literal, Protocol, overload

class str: pass
class dict: pass
class float: pass
class int:
    def __new__(cls) -> Literal[0]: pass

class _Truthy(Protocol):
    def __bool__(self) -> Literal[True]: pass

class _Falsy(Protocol):
    def __bool__(self) -> Literal[False]: pass

class bool(int):
    @overload
    def __new__(cls, __o: _Truthy) -> Literal[True]: pass
    @overload
    def __new__(cls, __o: _Falsy) -> Literal[False]: pass
    def __new__(cls, __o: object):
        pass
[typing fixtures/typing-medium.pyi]

It doesn't seem to work

No, move all that stuff from [file builtins.py] into actual fixture, e.g. in test-data/unit/fixtures/__new__.pyi

No, move all that stuff from [file builtins.py] into actual fixture, e.g. in test-data/unit/fixtures/__new__.pyi

Doing so doesn't seem to have changed anything, sorry if I'm misunderstanding

Hm, to debug this, try adding reveal_type(bool) to figure out when the problem happens, during definition, or when calling it.

bool is Any

Bumping because python/typeshed#6069 and python/typeshed#10465 depend on this.

According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅

Thank you @ilevkivskyi for helping with this much appreciated!