https://gcc.gnu.org/bugzilla/show_bug.cgi?id=20785
--- Comment #13 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> --- If the default state of these pragmas (at least with options like -std=c11) is respectively "off", "on", "off", then changing the pragma state can safely be ignored by the implementation, as implementations are not obliged to optimize as allowed by the new pragma state. Thus, in such a case, the warnings are useless.
