sorted() does not enforce comparable items in an iterable of tuples

[jcmacdon]

sorted() does not enforce that every item in the tuple must be comparable:

items: list[tuple[int, object]] = [(1, object()), (1, object())]
sorted(items)

typeshed/stdlib/builtins.pyi

Lines 1762 to 1767 in e5c5318

	@overload
	def sorted(
	iterable: Iterable[SupportsRichComparisonT], /, *, key: None = None, reverse: bool = False
	) -> list[SupportsRichComparisonT]: ...
	@overload
	def sorted(iterable: Iterable[_T], /, *, key: Callable[[_T], SupportsRichComparison], reverse: bool = False) -> list[_T]: ...

[ajaya0]

Hi @jcmacdon ,
Can you explain the issue in more detail so that I can resolve it?

[jcmacdon]

In my example items: list[tuple[int, object]] should not be sortable because it is a tuple which contains object which is not comparable.

I think the main issue here is actually not sorted() in particular but the fact that any tuple appears to be compatible with SupportsRichComparison.

This code typechecks ok:

from _typeshed import SupportsRichComparison

tuple1: SupportsRichComparison = (1, object())
tuple2: SupportsRichComparison = (1, object())

items = [tuple1, tuple2]
sorted(items)

but if you run it, you will get a runtime error:

TypeError: '<' not supported between instances of 'object' and 'object'

[ajaya0]

Hi @jcmacdon,

Thanks for the clarification! I see the issue now. The sorted() function was allowing tuples containing non-comparable types to be sorted, which caused the TypeError at runtime.