New failure on Python3.9

[sobolevn]

Latest minimal example: compile('A.\u018a\\ ', '<string>', 'single')

---

Hi! We are using hypothesmith to test our wemake-python-styleguide linter.
And today I got this failure:

self = <hypothesmith.syntactic.GrammarStrategy object at 0x7f702a236ee0>
data = ConjectureData(VALID, 1628 bytes, frozen)
symbol = NonTerminal('simple_stmt')
draw_state = DrawState(result=['\r\n \t\t\t \t \t\n #²\x97\x9c\n\t\r\n \t \t#\U000cf1a7`\x1e£Í\x0b#Ã\U0009460b\U00041f90\U000b0ffc§...b6¯\n#r×í@d¿\x08\r\n  \t\t\t\t\t\t \t\t\t  \t\t \t\t\t\t#\U000dca7e\U000cad5c?\U0005caae¤ÂÁ0Z\U000aa6eap#\U0010c8a6{'])

    def draw_symbol(self, data, symbol, draw_state):  # type: ignore
        count = len(draw_state.result)
        super().draw_symbol(data, symbol, draw_state)
        if symbol.name in COMPILE_MODES:
            try:
                compile(
                    source="".join(draw_state.result[count:]),
                    filename="<string>",
                    mode=COMPILE_MODES[symbol.name],
                )
            except SystemError as err:  # pragma: no cover
                # Extra output to help track down a possible upstream issue
                # https://github.com/Zac-HD/stdlib-property-tests/issues/14
                source_code = "".join(draw_state.result[count:])
>               raise Exception(
                    "unexpected error while attempting to compile "
                    f"{ascii(source_code)!r} in mode={COMPILE_MODES[symbol.name]}"
                ) from err
E               Exception: unexpected error while attempting to compile "'import\\u012c\\u0155u\\u011f\\u9782\\u0117\\xc4\\xd8.\\xcd\\u0179\\u0152\\u0139\\u010b\\xdb.\\xd0\\U0002852aD\\u017b\\xd6\\\\\\t \\t\\r\\nas#\\U0009a4a1\\u0178T\\u5408\\U00029fe8\\xcb\\u0141\\U0002b2b9\\u013c\\xf34D\\xd1p\\xf1\\t\\x0c \\x0c\\x0c \\x0c\\t\\x0c \\x0c\\t \\x0c\\x0c\\x0c \\\\\\x0c\\t\\n;pass\\r\\n\\t \\t\\t  \\r\\n\\r\\n\\t\\t\\t \\t\\t#\\x8b\\n\\r\\n  \\t\\t#\\xe6k\\x81E\\r\\n\\t  \\t \\t#\\U0001ed6b\\xd1#^\\r\\n \\r\\n  \\t\\r\\n  \\t\\t\\t #G\\x08\\x08#\\xe3^6\\xf1\\x87\\U000d8254\\U00070572 oQ}\\x10\\xce\\xc1\\U000563b6\\xaf\\n#r\\xd7\\xed@d\\xbf\\x08\\r\\n  \\t\\t\\t\\t\\t\\t \\t\\t\\t  \\t\\t \\t\\t\\t\\t#\\U000dca7e\\U000cad5c?\\U0005caae\\xa4\\xc2\\xc10Z\\U000aa6eap#\\U0010c8a6{'" in mode=single

.venv/lib/python3.9/site-packages/hypothesmith/syntactic.py:119: Exception
---------------------------------- Hypothesis ----------------------------------
You can add @seed(11935010665446469984514748066733166299) to this test or run pytest with --hypothesis-seed=11935010665446469984514748066733166299 to reproduce this failure.

Test file: https://github.com/wemake-services/wemake-python-styleguide/blob/master/tests/test_checker/test_hypothesis.py
Version used: 0.1.5

[Zac-HD]

Do you have the whole traceback? Even knowing what this exception was raised from would be very helpful!

[sobolevn]

Nope, that's it 😢

[Zac-HD]

Well, hopefully next time we'll have HypothesisWorks/hypothesis#2652 to help out!

[sobolevn]

It works locally, btw:

» poetry run pytest tests/test_checker/test_hypothesis.py --hypothesis-seed=11935010665446469984514748066733166299
================================ test session starts =================================
platform darwin -- Python 3.9.0, pytest-6.1.1, py-1.9.0, pluggy-0.13.1
Using --randomly-seed=3970102508
rootdir: /Users/sobolev/Documents/github/wemake-python-styleguide, configfile: setup.cfg
plugins: hypothesis-5.38.1, randomly-3.4.1, snapshottest-0.6.0, cov-2.10.1
collected 1 item                                                                     

tests/test_checker/test_hypothesis.py .     

[Zac-HD]

Yeah, I couldn't reproduce it either 😭

(not the first really tricky issue Hypothesmith has found, either... Unicode makes parsing hard!)

[sobolevn]

Shall I close it?

[sobolevn]

It happened again: https://github.com/wemake-services/wemake-python-styleguide/pull/1710/checks?check_run_id=1332703481

[Zac-HD]

That link goes to a passing build for me, without the check_run_id part 😕

[sobolevn]

Sorry! It was rebased and the link has changed. Direct link: https://github.com/wemake-services/wemake-python-styleguide/runs/1332703481?check_suite_focus=true

[Zac-HD]

No worries! I can definitely reproduce that, and even managed to reduce it a little further by hand. I've opened https://bugs.python.org/issue42218 but don't have any further advice beyond "consider skipping this on Python 3.9 for now" 😕

[Zac-HD]

Upstream fix is python/cpython#23058 🥰