This patch fixes a collection of miscellaneous problems that break the build with g++ 4.8.3. Thanks to Mats for pointing out two of the problems. I think the contents of this patch are fairly straightforward, with the exception of the changes to XSTRING_LENGTH and XSTRING_DATA. Before I made those changes, g++ 4.8.3 complained about a possibly uninitialized anonymous value in both alloc.c and fileio.c. I looked briefly at the code, thought it looked okay and that g++ must have lost its marbles, and continued on. Then, after building temacs, it segfaulted while loading lisp, at the exact line in fileio.c where one of the warnings was issued. More digging showed that g++ was creating anonymous temporaries, and not initializing them, instead of using the parameters that I thought it should access. Very weird. I don't understand what is going on there. It may be a bug in g++ 4.8.3, but on the other hand, those macros evaluate their arguments multiple times, which may have something to do with the problem. Anyway, let me know if you object to this solution.