https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112350
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- With optimization enabled and without -fsanitize=address we get: <source>: In function 'const int& foo1()': <source>:12:18: warning: using a dangling pointer to 'x' [-Wdangling-pointer=] 12 | return s.get(); | ^ <source>:9:9: note: 'x' declared here 9 | int x = 234; | ^