False positive not-a-mapping with cast and TypeVar

[phy1729]

Bug description

The following code results in a false positive. (The type hints may be removed; however, the cast and dummy assignment may not).

"""Docstring."""
from typing import TypeVar
from typing import cast


T = TypeVar('T')


def ident(thing: T) -> T:
    """Return thing."""
    return cast(T, thing)


_ = ident([])
dict(**ident({}))

Configuration

No response

Command used

pylint bug.py

Pylint output

************* Module bug
bug.py:15:7: E1134: Non-mapping value ident({}) is used in a mapping context (not-a-mapping)

Expected behavior

No error should be produced.

Pylint version

pylint 2.15.10
astroid 2.13.2
Python 3.10.9 (main, Dec 15 2022, 18:25:35) [Clang 14.0.0 (clang-1400.0.29.202)]

OS / Environment

macOS 13

Additional dependencies

No response

[clavedeluna]

worth mentioning that calling {**ident({})} does not cause this FP

also commenting out line _ = ident([]) makes the FP go away 🤔 so something is wrong with the inference here

[cdce8p]

Thanks for the report @phy1729! This will be fixed in pylint-dev/astroid#1982 and released probably with the next version.

[cdce8p]

The fixed cause a RecursionError to reappear. We are reverting the change for now.