Crash: AstroidError in refactoring_checker.py

[belm0]

Bug description

proprietary code, I haven't tried to narrow it down

pylint crashed with AstroidError and with the following stacktrace:

Traceback (most recent call last):
  File "/.../python3.8/site-packages/pylint/lint/pylinter.py", line 798, in _lint_file
    check_astroid_module(module)
  File "/.../python3.8/site-packages/pylint/lint/pylinter.py", line 1067, in check_astroid_module
    retval = self._check_astroid_module(
  File "/.../python3.8/site-packages/pylint/lint/pylinter.py", line 1117, in _check_astroid_module
    walker.walk(node)
  File "/.../python3.8/site-packages/pylint/utils/ast_walker.py", line 94, in walk
    self.walk(child)
  File "/.../python3.8/site-packages/pylint/utils/ast_walker.py", line 94, in walk
    self.walk(child)
  File "/.../python3.8/site-packages/pylint/utils/ast_walker.py", line 94, in walk
    self.walk(child)
  [Previous line repeated 2 more times]
  File "/.../python3.8/site-packages/pylint/utils/ast_walker.py", line 91, in walk
    callback(astroid)
  File "/.../python3.8/site-packages/pylint/checkers/refactoring/refactoring_checker.py", line 1731, in visit_comprehension
    self._check_unnecessary_list_index_lookup(node)
  File "/.../python3.8/site-packages/pylint/checkers/refactoring/refactoring_checker.py", line 2208, in _check_unnecessary_list_index_lookup
    has_start_arg, confidence = self._enumerate_with_start(node)
  File "/.../python3.8/site-packages/pylint/checkers/refactoring/refactoring_checker.py", line 2326, in _enumerate_with_start
    start_val, confidence = self._get_start_value(start_arg)
  File "/.../python3.8/site-packages/pylint/checkers/refactoring/refactoring_checker.py", line 2346, in _get_start_value
    return node.operand.value, HIGH
AttributeError: 'Attribute' object has no attribute 'value'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/.../python3.8/site-packages/pylint/lint/pylinter.py", line 763, in _lint_files
    self._lint_file(fileitem, module, check_astroid_module)
  File "/.../python3.8/site-packages/pylint/lint/pylinter.py", line 800, in _lint_file
    raise astroid.AstroidError from e
astroid.exceptions.AstroidError

Configuration

No response

Command used

pylint

Pylint output

n/a

Expected behavior

n/a

Pylint version

pylint 2.16.1
astroid 2.14.1
Python 3.8.12 (default, Sep 23 2021, 08:42:37)
[Clang 12.0.0 (clang-1200.0.32.29)]

OS / Environment

No response

Additional dependencies

No response

[orSolocate]

@belm0 - do you know what line (in the code Pylint checked) caused the crash? or any way to reproduce your error?

[belm0]

I was hoping it would be enough to imagine how the following might happen in the pylint code. If not, I'll try to whittle down the input.

  File "/.../python3.8/site-packages/pylint/checkers/refactoring/refactoring_checker.py", line 2346, in _get_start_value
    return node.operand.value, HIGH
AttributeError: 'Attribute' object has no attribute 'value'

[Pierre-Sassoulas]

Could you provide the value of the start attribute that is not an int inside an enumerate ? 😄

[belm0]

Could you provide the value of the start attribute that is not an int inside an enumerate ? 😄

Ah, that's exactly the code I've narrowed in on. Try this:

class Foo:
    def bar(self):
        return {
            (x, x): value
            for x, row in enumerate([(5, 10), (20, 30)])
            for y, value in enumerate(row, -self.unknown)}

In the original code, the attribute is defined, and it is an int type (no annotation, but the IDE infers it).

@Pierre-Sassoulas

[belm0]

the problem seems to be the unary minus

class Foo:
    def __init__(self):
        self.offset = -10

    def bar(self):
        return {
            (x, x): value
            for x, row in enumerate([(5, 10), (20, 30)])
            for y, value in enumerate(row, -self.offset)}

[Pierre-Sassoulas]

Thank you @belm0 amazing 👍