pylint Make ``superfluous-parens`` consider string combinations

Make ``superfluous-parens`` consider string combinations

Open DanielNoord opened this issue 2 years ago • 4 comments

Current problem

Although #4784 fixes some problems with superfluous-parens it still does not consider the following cases:

Z = "TestString"
X = ("Test " + "String") # Bad
Y = ("Test " + "String") in Z # Bad
assert "" + ("Version " + "String") in Z # Bad

This is because the current checker focuses on unnecessary parens after keywords (if, else, etc.) and only if the ( immediately follows the keyword. See

if tokens[start + 1].string != "(":
            return

on line 373 in format.py and the fact that we only run when Keywords are present.

Ideally, the checker would also consider string combinations and seeing if parens are necessary there.

Desired solution

Raise superfluous-parens message on the test cases described above.

Additional context

No response

Aug 03 '21 12:08 DanielNoord

Not sure if this is exactly the same as the thing mentioned above, so I am leaving it here first instead of creating a new issue.

The following code still produces superfluous-parens false-positive.

if not (a := dummy_func())
  return True

Here's the error message:

C0325: Unnecessary parens after 'not' keyword (superfluous-parens)

Versions:

pylint 2.9.6
astroid 2.6.6
Python 3.9.5 (tags/v3.9.5:0a7dcbd, May  3 2021, 17:27:52) [MSC v.1928 64 bit (AMD64)]

Syntax Reasoning

I can't use

if a := not dummy_func():
  return True

instead of

if not (a := dummy_func()):
  return True

because the first one only works if dummy_func() is returning bool. However, dummy_func is either returning None or some object, so I have to use the second one.