On Tue, Apr 3, 2018 at 5:58 PM, Samuel Thibault <samuel.thiba...@gnu.org> wrote: > Joseph Myers, on mar. 03 avril 2018 21:48:32 +0000, wrote: >> The build for i686-gnu also fails using GCC 6 branch with >> build-many-glibcs.py: >> >> hurdsig.c: In function 'interrupted_reply_port_location.isra.1': >> hurdsig.c:250:39: error: 'portloc' may be used uninitialized in this >> function [-Werror=maybe-uninitialized] >> *(volatile mach_port_t *) portloc = *portloc; >> ^~~~~~~~ >> >> I haven't investigated whether this warning is valid, or whether it's >> bogus > > Well, it's completely bogus: portloc is initialized just above. I don't > understand why it wouldn't see that.
I think it thinks the *value pointed-to by portloc* is uninitialized. Writing that value to a volatile memory location (which happens to be the same memory location, but you specifically told it not to pay attention to that with the volatile cast) is therefore invalid. I don't know this code well enough to suggest what you might could do about that. Since the warning does not happen with GCC 7 or 8 I would be fine with suppressing the diagnostic. zw
