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Sorry for not providing the simplest possible code to reproduce my problem, but I'm still new to spirit, I think I will miss some details in the conversion.
I tried add the inclusion you suggested, but it did not help.
Sorry, although it works for boost::tuple, it won't work for your Ipv4 struct...
But a simple workaround can solve this issue: in Ipv4Address grammar
change attribute to boost::tuple