Your second link seems to agree with my original post, i.e. it is not UB. Read on to point 20: http://port70.net/~nsz/c/c11/n1570.html#6.7.2.1p20 http://port70.

Your second link seems to agree with my original post, i.e. it is not UB. Read on to point 20: http://port70.net/~nsz/c/c11/n1570.html#6.7.2.1p20 http://port70.net/~nsz/c/c11/n1570.html#6.7.2.1p20 and it talks about my example of putting the struct in a malloc'd area of memory with space after the struct.