class IntWithDict:
    def __init__(self, **kwargs):
        self.kwargs = kwargs
    def __index__(self):
        self.kwargs.clear()
        L = [2**i for i in range(10000)]
        return 0
x = IntWithDict(dont_inherit=float())
compile("", "", "", x, **x.kwargs)


The above crashes CPython due to the usage of borrowed references in _PyStack_UnpackDict(): the dict x.kwargs contains the only reference to the float() object stored in x.kwargs

When parsing the arguments, x.__int__() is called, which clears the dict, removing the only reference to that float()