http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46914
--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-01-27 15:33:47 UTC --- Ok. In any case we should not risk miscompiling stuff, better bailing out at compile time. I see that in atomic_base.h the configure-time macros _GLIBCXX_ATOMIC_BUILTINS_* are used and I se no uses of the __GCC_HAVE_SYNC_COMPARE_AND_SWAP_* macros, the only one sensitive to the command line switches. But apparently the PR is about compiling *without* any special command line switch affecting the availability of the builtins, thus I don't see how things could possibly go wrong. Something also to keep in mind is that [GLIBCXX_ENABLE_ATOMIC_BUILTINS] in acinclude.m4 changed recently: I don't think we want to go through big efforts fixing this issue affecting only C++0x facilities in case it shows up only on 4.4.x, say, and it's fixed in mainline. I'll also try to run further tests in mainline, multilib too.
