W1514 unspecified-encoding false positive when mode is specified using a variable and it can be 'b' (binary mode)

[mitesh-raval]

Bug description

@contextmanager
def open_file_seek_zero(some_str, mode):
    ...
    with open(file_name, mode) as f:        # <===   this line is reported for W1514
        f.seek(0)
        yield f

============ above function usage ============
def some_other_func:
    with open_file_seek_zero(some_str, "r+b") as f:
        ...
==============================================

Configuration

Command used

pylint --rc=.pylintrc file_ops.py (made up file name)

Pylint output

************* Module file_ops
file_ops.py:29:9: W1514: Using open without explicitly specifying an encoding (unspecified-encoding)

Expected behavior

When file opening mode is not clearly discernable, unspecified-encoding should not be reported.

If I disable it in rc, I won't catch genuine errors.

Pylint version

pylint 3.3.3
astroid 3.3.8
Python 3.10.5

OS / Environment

No response

Additional dependencies

[Pierre-Sassoulas]

Thank you for opening the issue. I agree that when we don't know because we cannot infer we shouldn't raise a message.