http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59177
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> --- For hosted linux --enable-libstdcxx-time can work just fine, just use it. But, such a change isn't desirable for the branch, e.g. because the fancy checks require link tests which aren't usable for some bare metal configurations, might not be the right thing for Solaris or whatever else, etc. =auto has been introduced exactly to get some reasonably safe defaults automatically by default. So, if you want to change anything on the branch, supposedly it would be partial backport of the =auto stuff, but only limit it to the most commonly tested targets or something. Still, I'd say it is better to just tell people who want it to --enable-libstdcxx-time themselves if they want. In the past it has been ABI incompatible option, now hopefully is not.