https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52377
--- Comment #7 from dmitry.v.rogozhkin at intel dot com --- >> 2. The noted behavior to have 0 values for union members with -O: is that >> permanent behavior or we can randomly get non-zero values >If the member is initialized, we should get the correct value. Otherwise it's >undefined behavior. We get correct value which we tried to initialize on 4.9. But on 4.8 we don't and there are 2 cases: 1) if we compiled without -O we get random values, 2) if we compiled with -O, -O1/2/3 we get 0 while we tried to initialize to something else (to 4 in the example from bug description). I thought that the code change will shine the light on that, but unfortunately it does not, at least for me. So, I am trying to understand whether initialization to 0 on 4.8 compiler under -O option is a permanent behavior or we still may randomly get something else?
