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Python 3.5 is still crashing with this test:
$ python jump.py
> jump.py(7)<module>()
-> for i in gen():
(Pdb) break 3
Breakpoint 1 at jump.py:3
(Pdb) continue
> jump.py(3)gen()
-> yield i
(Pdb) step
--Return--
> jump.py(3)gen()->0
-> yield i
(Pdb) jump 2
> jump.py(2)gen()->0
-> for i in range(1):
(Pdb) continue
Segmentation fault (core dumped)
It is true that frame_setlineno() assumes incorrectly that f->f_stacktop is not NULL, but the reason of the crash or of the "SystemError: unknown opcode" is that PyEval_EvalFrameEx() expects on its invocation f->f_lasti to refer to the index of the last instruction executed and sets (and assumes this instruction does not have argument) 'next_instr' accordingly to the next byte, while by jumping to line 2 we set f->f_lasti to zero and 'SETUP_LOOP', the opcode at this index, has an argument.
The attached patch is a slight improvement over the last one.