Black 23.7.0 thinks accessing an attribute named type inside brackets in a switch statement is invalid syntax

[aucampia]

Describe the bug

When black encounters access of a .type attribute inside brackets, inside a switch statement, it thinks that it is invalid syntax, even though python 3.11 executes it just fine.

To Reproduce

For example, take this code:

class SomeClass:
    type = ""


match (SomeClass.type):
    case _:
        print("Hello there ...")

And run it with these arguments:

$ pipx run --python python3.11 --spec=black==23.7.0 black --target-version py311 --diff file.py

The resulting error is:

error: cannot format file.py: Cannot parse: 5:0: match (SomeClass.type):

Expected behavior

It should leave the file unchanged or format it, as black 23.3.0 leaves it unchanged, and it is indeed valid syntax:

$ python3.11 --version
Python 3.11.4
$ python3.11 file.py
Hello there ...
$ pipx run --python python3.11 --spec=black==23.3.0 black --target-version py311 --diff file.py
⚠️  black is already on your PATH and installed at /home/iwana/.local/bin/black. Downloading and running anyway.
All done! ✨ 🍰 ✨
1 file would be left unchanged.

Environment

• Black's version: 23.3.0
• OS and Python version: Linux/Python 3.11.4

[JelleZijlstra]

Thanks, cc @isidentical as this seems to be an interaction with the match-case support you added. I'll take a look too when I get a chance.

[richardxia]

In case it's helpful, I hit the same error in a slightly different way, which leads to a much more confusing error message, since the parser fails on the line after the match keyword rather than the line containing the match keyword itself. Here's an example case and its corresponding error message:

class Foo:
    type = "Foo"


foo = Foo()
bar = Foo()

match (foo.type, bar.type):
    case _:
        pass

Black's output:

error: cannot format blacktest.py: Cannot parse: 9:0:     case _:

Oh no! 💥 💔 💥
1 file failed to reformat.

Changing the attribute name to something other than type avoids the issue, as does assigning the match argument tuple to a variable before the match statement.

[wind-shift]

Hello, apparently I hit exactly the same bug

from collections import namedtuple
from typing import Any


class AAA:
    def do_xxx(
        self: Any,
    ):
        # Custom modules
        Foo = namedtuple("Foo", "a,b,type")
        foo0 = Foo(0, 1, 1)
        foo = Foo(0,1,1)
        match (foo.a, foo.type):
            case (foo0.a, foo0.b):
                return
            case _:
                raise ValueError("still rejected")

error: cannot format black_minimal_example.py: Cannot parse: 13:8:         match (foo.a, foo.type):

Oh no! 💥 💔 💥
1 file failed to reformat.

Applying this change:

-        match (foo.a, foo.type):
+        match (foo.a, foo.b):

makes black works again.

It’s working in black 23.3.0, but not with 23.9.0