Mypyc produces module that crashes (segmentation fault) when executed #18992

svalentin · 2025-04-28T16:36:09Z

compiled.py:

from typing import Generic, TypeVar

_T = TypeVar("_T")

class Bar(Generic[_T]):
    def __init__(self) -> None:
        self.value: str = 'start'
    def __get__(self, instance: _T, owner: type[_T] | None = None) -> str:
        return self.value
    def __set__(self, instance: _T, value: str) -> None:
        self.value = value

class Foo(object):
    bar: Bar = Bar()

Compiled with python3 -m mypyc compiled.py.

test.py:

import compiled

print("hello")

f = compiled.Foo()
print(f.bar)

f.bar = 'test'
print(f.bar)

And running with:

$ python3 test.py
hello
<compiled.Bar object at 0x7464e7774310>
Segmentation fault

Using current master of mypyc:

$ python3 -m mypyc --version
mypy 1.16.0+dev.7b4f6311e29452cc8d4ddb78331d0047c8b17e93.dirty (compiled: no)

Using Python 3.13.1

If running with python3 directly:

$ python3 test.py
hello
start
test

The text was updated successfully, but these errors were encountered:

svalentin · 2025-05-02T17:14:12Z

Output when using a debug version of python:

$ python3 test.py
hello
<compiled.Bar object at 0x7cc5bb0dfde0>
Traceback (most recent call last):
  File "/home/svalentin/src/mypy-svalentin/test/test.py", line 8, in <module>
    f.bar = 'test'
    ^^^^^
TypeError: compiled.Bar object expected; got str
Segmentation fault

svalentin added crash topic-mypyc mypyc bugs labels Apr 28, 2025

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Mypyc produces module that crashes (segmentation fault) when executed #18992

Mypyc produces module that crashes (segmentation fault) when executed #18992

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Mypyc produces module that crashes (segmentation fault) when executed #18992

Mypyc produces module that crashes (segmentation fault) when executed #18992

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