No, not usually. They mostly mean that the compiler is much newer than the programmer's habits and/or sections of the code, and are intended to notify code authors of things that are changing. I seriously doubt there is much code out there that does not generate some of these, but older code will likely cause more.
Also, the GNU compiler (gcc,g++) is noted for being very verbose in the messages that it generates, but no harm.
As long as it compiles without actual errors, it will almost certainly work as intended.
Last edited by astrogeek; 11-19-2015 at 01:27 AM.