'ListComp' object has no attribute 'name' when variable is named "type"

[xavfernandez]

Bug description

Pylint/Astroid crashes on list comprehension using a variable named type.

$ cat test.py 
[type for type in [] if type['id']]

crashes but

$ cat test.py 
[toto for toto in [] if toto['id']]

doesn't.

Configuration

No response

Command used

pylint test.py

Pylint output

************* Module test
test.py:1:0: C0114: Missing module docstring (missing-module-docstring)
test.py:1:0: W0104: Statement seems to have no effect (pointless-statement)
Exception on node <Subscript l.1 at 0x7f919c740040> in file '/home/xafer/.virtualenvs/tmp-5062295dba883df/test.py'
Traceback (most recent call last):
  File "/home/xafer/.virtualenvs/tmp-5062295dba883df/lib/python3.9/site-packages/astroid/inference_tip.py", line 28, in _inference_tip_cached
    result = _cache[func, node]
KeyError: (<function infer_type_sub at 0x7f919cc4d1f0>, <Name.type l.1 at 0x7f919c7400d0>)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/xafer/.virtualenvs/tmp-5062295dba883df/lib/python3.9/site-packages/pylint/utils/ast_walker.py", line 72, in walk
    callback(astroid)
  File "/home/xafer/.virtualenvs/tmp-5062295dba883df/lib/python3.9/site-packages/pylint/checkers/typecheck.py", line 1820, in visit_subscript
    self._check_invalid_sequence_index(node)
  File "/home/xafer/.virtualenvs/tmp-5062295dba883df/lib/python3.9/site-packages/pylint/checkers/typecheck.py", line 1510, in _check_invalid_sequence_index
    parent_type = safe_infer(subscript.value)
  File "/home/xafer/.virtualenvs/tmp-5062295dba883df/lib/python3.9/site-packages/pylint/checkers/utils.py", line 1242, in safe_infer
    value = next(infer_gen)
  File "/home/xafer/.virtualenvs/tmp-5062295dba883df/lib/python3.9/site-packages/astroid/nodes/node_ng.py", line 146, in infer
    results = list(self._explicit_inference(self, context, **kwargs))
  File "/home/xafer/.virtualenvs/tmp-5062295dba883df/lib/python3.9/site-packages/astroid/inference_tip.py", line 30, in _inference_tip_cached
    result = _cache[func, node] = list(func(*args, **kwargs))
  File "/home/xafer/.virtualenvs/tmp-5062295dba883df/lib/python3.9/site-packages/astroid/brain/brain_type.py", line 51, in infer_type_sub
    if node_scope.qname() != "builtins":
  File "/home/xafer/.virtualenvs/tmp-5062295dba883df/lib/python3.9/site-packages/astroid/nodes/scoped_nodes.py", line 246, in qname
    return f"{self.parent.frame().qname()}.{self.name}"
AttributeError: 'ListComp' object has no attribute 'name'
test.py:1:0: F0001: Fatal error while checking 'test.py'. Please open an issue in our bug tracker so we address this. There is a pre-filled template that you can use in '/home/xafer/.cache/pylint/pylint-crash-2021-12-03-11.txt'. (fatal)

---------------------------------------------------------------------
Your code has been rated at -10.00/10 (previous run: 0.00/10, -10.00)

Expected behavior

No crash

Pylint version

pylint 2.12.1
astroid 2.9.0
Python 3.9.9 (main, Nov 20 2021, 21:30:06) 
[GCC 11.1.0]

OS / Environment

No response

Additional dependencies

astroid==2.9.0
isort==5.10.1
lazy-object-proxy==1.6.0
mccabe==0.6.1
platformdirs==2.4.0
pylint==2.12.1
toml==0.10.2
typing_extensions==4.0.1
wrapt==1.13.3

[cdce8p]

@xavfernandez Thanks for opening the issue. Personally, I wouldn't recommend to use type for anything other than the builtin function and as generic type but this crash can nevertheless be fixed. For reference: pylint-dev/astroid#1284 (review)

[xavfernandez]

@cdce8p Yes, I usually also avoid builtin names (and I actually fixed the crash in my build by renaming the variable).
The issue appeared when I was migrating a legacy project from Python 3.8 to Python 3.9.

And now that I think about it, the bug doesn't happen in Python 3.8:

$ cat test.py
[type for type in [] if type['id']]
$ pylint --version
pylint 2.12.2
astroid 2.9.0
Python 3.8.9 (default, May 19 2021, 07:50:51) 
[GCC 10.2.0]
$ pylint test.py
************* Module test
test.py:1:0: C0114: Missing module docstring (missing-module-docstring)
test.py:1:0: W0104: Statement seems to have no effect (pointless-statement)

----------------------------------------------------------------------
Your code has been rated at -10.00/10 (previous run: -10.00/10, +0.00)

vs

$ cat test.py
[type for type in [] if type['id']]
$ pylint --version
pylint 2.12.2
astroid 2.9.0
Python 3.9.9 (main, Nov 20 2021, 21:30:06) 
[GCC 11.1.0]
$ pylint test.py
************* Module test
test.py:1:0: C0114: Missing module docstring (missing-module-docstring)
test.py:1:0: W0104: Statement seems to have no effect (pointless-statement)
Exception on node <Subscript l.1 at 0x7fb9a5f624f0> in file '/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/test.py'
Traceback (most recent call last):
  File "/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/lib/python3.9/site-packages/astroid/inference_tip.py", line 28, in _inference_tip_cached
    result = _cache[func, node]
KeyError: (<function infer_type_sub at 0x7fb9a64715e0>, <Name.type l.1 at 0x7fb9a5f625b0>)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/lib/python3.9/site-packages/pylint/utils/ast_walker.py", line 72, in walk
    callback(astroid)
  File "/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/lib/python3.9/site-packages/pylint/checkers/typecheck.py", line 1820, in visit_subscript
    self._check_invalid_sequence_index(node)
  File "/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/lib/python3.9/site-packages/pylint/checkers/typecheck.py", line 1510, in _check_invalid_sequence_index
    parent_type = safe_infer(subscript.value)
  File "/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/lib/python3.9/site-packages/pylint/checkers/utils.py", line 1251, in safe_infer
    value = next(infer_gen)
  File "/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/lib/python3.9/site-packages/astroid/nodes/node_ng.py", line 146, in infer
    results = list(self._explicit_inference(self, context, **kwargs))
  File "/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/lib/python3.9/site-packages/astroid/inference_tip.py", line 30, in _inference_tip_cached
    result = _cache[func, node] = list(func(*args, **kwargs))
  File "/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/lib/python3.9/site-packages/astroid/brain/brain_type.py", line 51, in infer_type_sub
    if node_scope.qname() != "builtins":
  File "/home/xafer/.virtualenvs/tmp-6d7976bdba8cd7/lib/python3.9/site-packages/astroid/nodes/scoped_nodes.py", line 246, in qname
    return f"{self.parent.frame().qname()}.{self.name}"
AttributeError: 'ListComp' object has no attribute 'name'
test.py:1:0: F0001: Fatal error while checking 'test.py'. Please open an issue in our bug tracker so we address this. There is a pre-filled template that you can use in '/home/xafer/.cache/pylint/pylint-crash-2021-12-06-10.txt'. (fatal)

----------------------------------------------------------------------
Your code has been rated at -10.00/10 (previous run: -10.00/10, +0.00)

[cdce8p]

And now that I think about it, the bug doesn't happen in Python 3.8

That's to be expected. The bug is related to the handling of builtin types in Python 3.9 and higher. It will be fixed with pylint-dev/astroid#1285.

[DanielNoord]

@cdce8p Do we still want to add a test for this in pylint?

[DanielNoord]

Made a PR with little regression test