Cython mishandles PEP-3135 __class__ cell in methods #2912
Description
Hello, I am having trouble with some inconsistent behaviour round the value of __class__ in Cythonized code. This is on Python 3.6.7 with Cython 0.29.1.
Briefly, in uncythonized code __class__ inside a method on a class refers to the class object, whereas once cythonized, it seems to refer to <class 'module'>. This behaviour is a bit unintuitive, and has caused a few issues in a codebase I'm working on, but it's possible I have misunderstood the language semantics!
I have tried to search for reasons / documentation why this is the case, but I couldn't turn up anything. I apologise if there is something really obvious I'm missing here; let me know if so and I'll close the issue at once.
Example:
minimal.py:
class Something:
def method(self):
print(__class__)
(in an interpreter, uncythonized):
from minimal import Something
Something().method()
# prints <class 'minimal.Something'>
(after running cythonize minimal.py -3):
from minimal import Something
Something().method()
# prints <class 'module'>
I believe there is an obvious workaround -- in instance methods, self.__class__ should still have the correct value. But I was curious if this is intended behaviour, and if so, is there something in the docs about it?
