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Fix a crash when inferring a typing.TypeVar call. #2239

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merged 7 commits into from
Jul 17, 2023
Merged

Fix a crash when inferring a typing.TypeVar call. #2239

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f15d7b9
Fix a crash when inferring a `typing.TypeVar` call.
mbyrnepr2 Jul 6, 2023
6f97305
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Jul 6, 2023
cc15e24
Remove unused import and move module.
mbyrnepr2 Jul 6, 2023
5f2e6fc
Move Changelog entry to the `2.15.6` milestone.
mbyrnepr2 Jul 13, 2023
017c218
Move Changelog entry to the `2.15.7` milestone.
mbyrnepr2 Jul 13, 2023
1b3355c
Add release date to the Changelog for the `2.15.6` release.
mbyrnepr2 Jul 13, 2023
ea5dd00
Add type annotations to function definition.
mbyrnepr2 Jul 13, 2023
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11 changes: 10 additions & 1 deletion ChangeLog
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Original file line number Diff line number Diff line change
Expand Up @@ -196,10 +196,19 @@ Release date: TBA
Refs #2204


What's New in astroid 2.15.6?
What's New in astroid 2.15.7?
=============================
Release date: TBA

* Fix a crash when inferring a ``typing.TypeVar`` call.

Closes pylint-dev/pylint#8802


What's New in astroid 2.15.6?
=============================
Release date: 2023-07-08

* Harden ``get_module_part()`` against ``"."``.

Closes pylint-dev/pylint#8749
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13 changes: 11 additions & 2 deletions astroid/brain/brain_typing.py
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Expand Up @@ -118,7 +118,9 @@ def looks_like_typing_typevar_or_newtype(node) -> bool:
return False


def infer_typing_typevar_or_newtype(node, context_itton=None):
def infer_typing_typevar_or_newtype(
node: Call, context_itton: context.InferenceContext | None = None
) -> Iterator[ClassDef]:
"""Infer a typing.TypeVar(...) or typing.NewType(...) call."""
try:
func = next(node.func.infer(context=context_itton))
Expand All @@ -134,7 +136,14 @@ def infer_typing_typevar_or_newtype(node, context_itton=None):
raise UseInferenceDefault

typename = node.args[0].as_string().strip("'")
node = extract_node(TYPING_TYPE_TEMPLATE.format(typename))
node = ClassDef(
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Shall we add the Meta class as base? Then we still have the __getitem__ inference correctly.

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Thanks for such quick feedback👍.
I started a short vacation right after opening this so I’ll think about a test case when I can.

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Hey @DanielNoord I've taken a look finally :)

It seems to me there is no need for __getitem__ to be attached to the astroid node representing either typing.TypeVar or typing.NewType since neither of these are subscriptable. What do you think?
Similar point for __args__ since that is used to fetch the arguments used in subscripting.

As a sidenote - __getitem__ is already part of nodes.ClassDef since it inherits that method from LocalsDictNodeNG.

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Okay! Can we then remove that code?

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I took a look into that just now. The template is used by this function which needs the __args__ member since the function is inferring subscriptable types.
As an illustration, If I were to remove the code and use a similar ClassDef construction for the code above, this unitest fails:
FAILED astroid/tests/brain/test_brain.py::TypingBrain::test_has_dunder_args - astroid.exceptions.InferenceError: StopIteration raised without any error information.
In other words, running Pylint on this code:

from typing import Union
NumericTypes = Union[int, float]
NumericTypes.__args__ #@

...gives: E1101: Class 'Union' has no '__args__' member (no-member)

name=typename,
lineno=node.lineno,
col_offset=node.col_offset,
parent=node.parent,
end_lineno=node.end_lineno,
end_col_offset=node.end_col_offset,
)
return node.infer(context=context_itton)


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24 changes: 24 additions & 0 deletions tests/brain/test_typing.py
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@@ -0,0 +1,24 @@
# Licensed under the LGPL: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.en.html
# For details: https://github.com/pylint-dev/astroid/blob/main/LICENSE
# Copyright (c) https://github.com/pylint-dev/astroid/blob/main/CONTRIBUTORS.txt

from astroid import builder, nodes


def test_infer_typevar() -> None:
"""
Regression test for: https://github.com/pylint-dev/pylint/issues/8802

Test that an inferred `typing.TypeVar()` call produces a `nodes.ClassDef`
node.
"""
assign_node = builder.extract_node(
"""
from typing import TypeVar
MyType = TypeVar('My.Type')
"""
)
call = assign_node.value
inferred = next(call.infer())
assert isinstance(inferred, nodes.ClassDef)
assert inferred.name == "My.Type"
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