overloaded function with broken with map dependent on order of overload definitions

[DerBiasto]

Describe the Bug

I have a function taking some value or None that returns a value of the same type.

When trying to map that function onto an iterable of values, pyrefly gives an error, but only if the None overload is defined first. Moving the overload for done after any other overload, resolves this error.

from typing import overload, reveal_type

@overload
def foo(x: None) -> None: ...

@overload
def foo(x: float) -> float: ...

@overload
def foo(x: int) -> int: ...

def foo(x: int | float | None) -> int | float | None:
    return x

def bar(items: tuple[int, ...]):
    for x in map(foo, items):  # Argument `tuple[int, ...]` is not assignable to parameter `iterable` with type `Iterable[None]` in function `map.__new__` [bad-argument-type]
        reveal_type(x)

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeS4ATrgLYAEALqcROgOZ0Q3G6UN24AbjEpRcqTABo6lGMNRQA%2Bk2IwAOug0ABISLESNmGGDphcuABT5EdAHK50MAJR0AtAD47DmDcJ%2BN2rqi4piGxqbmVjZg%2BgwuHqaxvv6a6DrCwQZY4WaW1pzocW6erAzJhAHZJrlRBfwAPoniDV6O8SWFdI0xzV2tPhp0QzIwDACulOh0%2BJVGJtiolBYQDDA0cDbjxLAA2qXSfoQAuk6Ig8NmlNMFdDSoxBa50itrcKfnw8Oy8koqMFZODQgSQgMiyGKkQgMWhQCgAYjoAAVSOCoKQ6GgsHh8HQAMYOSBsCaoBgQBwVdAIgDKMBgdAAFgwGMQNgB6Vlg4xowi8NismDoVmYXC4uCs-HoQnE0kOVkRK6oQSoaCobCwPEEiBEygkslTXDEGXoOAUsgMekOVwZOB6ugAXjoahAAGZCABGABMTo0OxE1EocCOGjG6C4PD4MEwrkwEFkuNJwntdAA5Fr0LwYMmNOmGK5ZABHMaxyOuADWMFIrlQuNx8DgSeTAHdFugs%2BgQABfEHVhMwABi0BgFExOAIJHIHaAA

(Only applicable for extension issues) IDE Information

No response

[rchen152]

Thanks for the report! It looks like the issue is here:

pyrefly/pyrefly/lib/solver/subset.rs

Lines 1118 to 1124 in 2727410

	if any(overload.signatures.iter(), |l| {
	self.is_subset_eq(&l.as_type(), want)
	})
	.is_ok()
	{
	return Ok(());
	}

. We iterate through the overloads for foo and stop at the first one that satisfies the corresponding parameter type in map.

[DerBiasto]

Possibly (probably?) related:

def foo(items: list[str]):
    print(map("".join, items))  # Argument `list[str]` is not assignable to parameter `iterable` with type `Iterable[Iterable[LiteralString]]` in function `map.__new__` [bad-argument-type]

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeSImMYABGLrgBQQAuMAtnIjVBHCwG1%2BAJwC6ASkQAddDTk1iwiOhaN2qYoykhthAFa5lAGhqsOcceJBGQZYdSilCLXOygUAxDQAKpe2EcaNCw8fBoAY1x0SABzAFdhVBYIKMIZLwBlGBgaAAsWFmIuAHpiuwcnXGEY4ph0YsxccLhiyOiIeMTkqOK6KppUADdUaFRsWAio2ISklNlcYm70ODT0MhZcqIBaQZhhODmaAF4abQBmQgBGACZtGQE94Sq4URk49Ah2Yiq2TC3MCD2cLJXbHGgAcg66CqMHBMmhLC29gAjnFATA-gBrGCkLaocLheBwMHggDuqGE6Dh6BAAF8bPiQTAAGLQGAUYI4Agkci0oA

[jorenham]

Possibly (probably?) related:

def foo(items: list[str]):
print(map("".join, items)) # Argument list[str] is not assignable to parameter iterable with type Iterable[Iterable[LiteralString]] in function map.__new__ [bad-argument-type]
pyrefly.org/sandbox?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeSImMYABGLrgBQQAuMAtnIjVBHCwG1%2BAJwC6ASkQAddDTk1iwiOhaN2qYoykhthAFa5lAGhqsOcceJBGQZYdSilCLXOygUAxDQAKpe2EcaNCw8fBoAY1x0SABzAFdhVBYIKMIZLwBlGBgaAAsWFmIuAHpiuwcnXGEY4ph0YsxccLhiyOiIeMTkqOK6KppUADdUaFRsWAio2ISklNlcYm70ODT0MhZcqIBaQZhhODmaAF4abQBmQgBGACZtGQE94Sq4URk49Ah2Yiq2TC3MCD2cLJXbHGgAcg66CqMHBMmhLC29gAjnFATA-gBrGCkLaocLheBwMHggDuqGE6Dh6BAAF8bPiQTAAGLQGAUYI4Agkci0oA

str.join is also overloaded, so that seems likely:
https://github.com/python/typeshed/blob/eec9fe9aa9ce87df8987de5c1401f743e179378a/stdlib/builtins.pyi#L525-L528