It seems that my memory does not serve me well :) ISO C actually explicitly specifies that the order is same in §6.7.2.1.13. The "deduced" remark was essentia

It seems that my memory does not serve me well :) ISO C actually explicitly specifies that the order is same in §6.7.2.1.13. The "deduced" remark was essentially intended to cover constraints that come from 6.2.6.1.2 ("...objects are composed of contiguous sequences of one or more bytes..."), ie. fields cannot be (conceptually) outside &foo and ((char*)&foo)+sizeof(foo), which can be hard to implement on sufficiently weird architectures.