return value of sorted() cannot be upcast

Bug Report

Mypy allows the return value of list() to be upcasted. eg. list[int] -> list[object] (or list[int | None]). Mypy does not permit the same behaviour with the return value of sorted(). Like list(), sorted() is a builtin, creates a new list, and does not retain a reference to the returned value. Mypy should allow the return value of sorted() to be upcast, because it is safe to do so.

To Reproduce

# file: foo.py
ints: list[int] = [1,2,3]
objects: list[object] = sorted(ints) # error!

Command line:

python -m mypy foo.py

Expected Behavior

That no error should be reported, much like if list() were used instead of sorted(). ie:

ints: list[int] = [1, 2, 3]
objects: list[object] = list(ints)

# undesirable work around 
objects2: list[object] = list(sorted(ints))

Actual Behavior

foo.py:11: error: Incompatible types in assignment (expression has type "list[int]", variable has type "list[object]")  [assignment]
foo.py:11: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
foo.py:11: note: Consider using "Sequence" instead, which is covariant
Found 1 error in 1 file (checked 1 source file)

Your Environment

• Mypy version used: 1.10.0
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: 3.12.0

Commencez par exécuter python -m mypy foo.py avec la reproduction fournie dans l’issue, puis examinez la manière dont mypy gère les types de retour de list() et sorted(). Suivez les chemins pertinents de vérification des types pour les builtins et les listes génériques ; le travail est terminé lorsque l’affectation montrée sorted(ints) ne produit aucune erreur sans nécessiter le contournement list(sorted(ints)).