[BUG] Crash due to duplicate __PYX_XCLEAR_MEMVIEW

[fanosta]

Describe the bug

When using a property setter that accepts a memory view, Python crashes with the following error:

Fatal Python error: __pyx_fatalerror: Acquisition count is -1 (line 16959)
Python runtime state: initialized

Current thread 0x00000001e83a1e00 (most recent call first):
  File "/private/tmp/cdtmp.l8Y/test.py", line 7 in <module>

Extension modules: cython.cimports.libc.math, foo (total: 2)

Code to reproduce the behaviour:

# foo.pyx
cdef class Foo:
    @property
    def bar(self):
        return b'bar'

    @bar.setter
    def bar(self, const unsigned char[::1] bar):
        pass

# test.py
#!/usr/bin/env python3

from pyximport import install; install()
from foo import Foo

c = Foo()
c.bar = b'some string'  # <-- this crashes

In the generated foo.c, I can see the following code where __PYX_XCLEAR_MEMVIEW is called twice on the same variable which is likely the cause of the bug:

/* Python wrapper */
static int __pyx_pw_3foo_3Foo_3bar_3__set__(PyObject *__pyx_v_self, PyObject *__pyx_arg_bar); /*proto*/
static int __pyx_pw_3foo_3Foo_3bar_3__set__(PyObject *__pyx_v_self, PyObject *__pyx_arg_bar) {
  /* ... */

  /* function exit code */
  __PYX_XCLEAR_MEMVIEW(&__pyx_v_bar, 1);
  __PYX_XCLEAR_MEMVIEW(&__pyx_v_bar, 1);
  __Pyx_RefNannyFinishContext();
  return __pyx_r;
}

Expected behaviour

The code is executed without crashing the Python interpreter.

OS

macOS

Python version

Python 3.11.4

Cython version

Cython version 3.0.0

Additional context

I can also reproduce the error on Debian 11 with Cython 3.0.0 and Python 3.9.2

[da-woods]

So the double __PYX_XCLEAR_MEMVIEW isn't right, but it should be safe. The crash is actually on the first one

[fanosta]

Thank you for debugging the code and creating a patch.