I think you're confusing unspecified and undefined behavior. UB could do something randomly different every time and unspecified must chose an option. In a lot

I think you're confusing unspecified and undefined behavior. UB could do something randomly different every time and unspecified must chose an option. In a lot of cases in optimizing compilers they just assume UB doesn't exist. Yes technically the compiler does do something but there's still a big difference between the two.