http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60906
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC has like 60 or 70 target independent attributes plus sometimes various
target dependent attributes. Figuring out which are ABI changing and must be
errored out on mismatch, which are safe to ignore, which are only affecting
function generation and not callers is going to be hard even for the existing
ones, and would be a maintainance burden for the future, as for each new
attribute (every year a few of them are added) it would be another place to
modify and think about what the behavior should be. Keying something on
default attribute would be weird, for multi-versioning you don't have to have
target ("default") I think. If you want to inherit the attributes, perhaps
from the first decl only, and if the second/further multi-versioned
declarations or definitions add attributes (other than the target attribute),
it would be only allowed if the attribute wouldn't modify the attribute list
(i.e. contain attribute that is already present).
