Call cycle causes infinite recursion

[mattip]

array_iter_impl -> HPySeqIter_New -> look up __iter__ and call it -> array_iter_impl.

You can hit this by doing np.range(10).__iter__(). This was added in 3a7a0d2.

For some reason calling src_cycle = cycle(self.pool) in setting up the random.bit_generator is hitting this in PyPy but not in CPython. Maybe cycle is implemented slightly differently in CPython, and avoids calling self.pool.__iter__().

[mattip]

On CPython, it seems HPyDef_METH(array_iter, "__iter__", HPyFunc_NOARGS) does not push the __dict__ function into the tp_iter slot, so CPython does not hit this problem. Instead, the __new__ function for the c implementation of itertools.cycle will call PySeqIter_New(ndarray), which wraps the ndarray in a new iter object.

[mattip]

@fangerer any thoughts?

[fangerer]

@fangerer any thoughts?

Interesting, I thought CPython would also push the __iter__ member back to the tp_iterslot. See update_one_slot.
I guess we need to investigate in the debugger what path CPython takes.