http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51628
--- Comment #13 from rguenther at suse dot de <rguenther at suse dot de> 2011-12-20 13:21:02 UTC --- On Tue, 20 Dec 2011, ebotcazou at gcc dot gnu.org wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51628 > > --- Comment #11 from Eric Botcazou <ebotcazou at gcc dot gnu.org> 2011-12-20 > 12:25:13 UTC --- > > You can. Just check what you get with that aligned(1) int typedef. > > Well, we're going in circles as this example precisely doesn't work. > > > Is it documented anywhere that you can't take the address of > > an unaligned structure member (given the struct is packed) on > > STRICT_ALIGNMENT targets (or, when it's a vector component even > > on non-STRICT_ALIGNMENT targets)? Why does the C frontend not > > warn for these cases (unconditionally?)? > > Good question, but for a C maintainer. The C front-end would have implemented > something for a long time if it had cared about the issue, but apparently not. > In Ada we do care since Ada 2005, so we have implemented the necessary > support. Fact is, the middle-end needs a way to support this (well, or "wants"). Otherwise stripping off component-refs does not work even for the "long time working cases". "Fixes" to avoid stripping them away are not really fixes but workarounds around fixing this long-time issue. But I see you are not going to work on fixing the expansion side (which I hoped, since you have plenty of experience in this area and strict-alignment targets)
